Case Based Scenarios in Pediatric Oncology Rachna Seth, Jagdish P Meena, Aditya Kumar Gupta
INDEX
Page numbers followed by f refer to figure, fc refer to flowchart, and t refer to table.
A
Abelson murine leukemia virus 161
Absolute neutrophil count 211, 280, 319
Activated partial thromboplastin time 127, 256
Acute lymphoblastic leukemia 1
relapse 19, 20t, 21t
Acute myeloid leukemia 40, 41, 43fc, 46, 49, 58, 60, 68, 74, 90, 91, 165, 295, 301, 302, 305, 307, 319, 328
management of 57, 72
prognostic factors in 59t
relapse 58
Acute promyelocytic leukemia 126f, 127, 127f, 130
morphology of 124f
Adrenal hypoplasia 244
Adriamycin 222, 230, 279, 336
Advanced myelodysplastic syndrome 246
Alanine aminotransferase 153
Alkalinization 296
Allogeneic hematopoietic cell 328
Allogeneic transplantation 229
Allopurinol 296
All-trans-retinoic acid 127f
dose of 131
Amphotericin B deoxycholate 327
Amsacrine cytarabine etoposide 46, 60
Anakinra 272
Anaplastic large cell lymphoma 171, 177, 179, 181, 182, 185, 295
pathogenesis of 175
Anaplastic lymphoma kinase 174, 177, 178f
Anemia 242
aplastic 245
hemolytic 281
refractory 243
severe 306
aplastic 241
sideroblastic 241
Anesthesia 336
local 313
Angiotensin converting enzyme 67
Ann Arbor staging classification 221f, 221t
Anthracyclines 27, 314
antibiotics 64
free regimen 136
Anti-anaplastic lymphoma kinase antibodies 179
Antibacterial prophylaxis 327
role of 48
use of 48
Antibiotic
discontinuation of 324
empirical 323
prophylaxis 327
Antibody drug conjugates 47
Anticytokine 272
Antifungal prophylaxis 48, 328
role of 48
Antifungal therapy 326
Antipneumocystis prophylaxis 328
Antithymocyte globulin 246
Antiviral prophylaxis 328
Aortic aneurysm 309, 310
Apple core appearance 124f
Arrhythmias, cardiac 332
Ascites 254
Asparaginase 27
Aspergillosis 48
Aspergillus flavus 297
Autoimmune lymphoproliferative disorders 280
Autoimmune lymphoproliferative syndrome 249, 275, 280, 283, 285
management of 285, 286fc
Autoimmunity 281
Autologous stem cell transplant 228, 229
Azacitidine, role of 164
B
Basophilia 102, 138f, 140
Basophils 102
B-cell 22
lymphomas 196
receptor 207, 214
Bendamustine 232
Berlin-Frankfurt-Münster 23, 46, 60, 91, 93, 206
Beta-D-glucan 326
Bilineage cytopenia 242
Biopsy 336
abdominal 205f
Birbeck granule 268
Blast crisis 102, 142
Blastic transformation 163
Bleomycin 222, 230, 336
Blinatumomab 11, 30, 34, 82
role of 32
Blood 317
cell 139
component therapy 304
culture 317
Bone 255
health 223
Bone marrow 4, 21, 46, 89, 142, 156, 160, 161, 242, 244, 245, 245f
aspirate cytology 20f
aspiration 24f
examination 313
transplant 220, 337
trephine biopsy 139f
Bony lesions 16
Bradycardia 333
BRAF-v600e mutation 275, 277
Brentuximab vedotin 177, 182, 229, 230
Bronchoalveolar lavage 172f, 256, 326
Bruton's tyrosine kinase 214
Bulky disease 333
role of 6
Burkitt's leukemia 332
Burkitt's lymphoma 205, 208f, 214f, 217
management of 217
pathogenesis of 207f
Burkitt's pathogenesis 207
C
Cairo-Bishop classification 332
Calcium 298, 315
Calycectasia, diffuse 272
Carbon
dioxide 310
monoxide 65
Carboplatin 220, 228, 229
Cardiac dysfunction 50, 67, 234
Cardiomyocytes, death of 67
Cardiorespiratory collapse, high risk of 336
Cardiotoxicity 66, 234
prevention of 65
Cardiovascular disease 66
Carmustine 232
Castleman disease 280
Cefepime 321
Central nervous system 20, 21, 24, 32, 75, 77, 93, 102, 140, 160, 174, 206, 210, 252, 259, 271, 274, 301
prophylaxis 78, 131
Cephalosporin monotherapy 321
Cerebral parenchyma 25
Cerebral venous thrombosis 128f
Cerebrospinal fluid 21, 22, 194, 211, 318, 326
Ceritinib 178
Chemorefractory, prognosis of 229
Chemotherapy 11, 17, 57, 63, 131, 136, 148f, 169, 335, 337
agents 25
completion of 234
cycles 229, 327
drugs 222
free approach 132
low-dose 335
maintenance 30f, 261
metronomic 72
myeloablative 319
postreinduction 30
postsalvage 213f
post-transplant 164
pre-transplant 164
reinduction 28, 224
role of 57, 163
standard-dose 226
Chest X-ray 256, 309f, 318
Children's cancer group 78
Children's oncology group 47, 63, 77, 93
Chimeric antigen receptor 11, 31, 82
Cholesterol efflux 274
Chromosomal microarray analysis 56
Chromosome abnormalities 146
Chronic cervical lymphadenopathy, differential diagnosis of 188t
Cisplatin 212, 230
Cladribine 261, 261f, 272
Coagulopathy, mechanism of 125
Colony-stimulating factor 78, 274
Combination therapy 321
Complete blood count 69, 312
Complex inflammatory response 270
Computed tomography 254, 260, 261, 266
scan image 172f
Consolidation chemotherapy 30f
Continuous arteriovenous hemofiltration 299
Continuous venovenous hemofiltration 299
Core needle biopsy 173f
Corticosteroids 285
Cranial nerve palsy 211
Crizotinib 178, 186
Cyclin dependent kinases 207
Cyclophosphamide 62, 78, 210, 222, 233, 234, 279
addition of 334
Cyst
duplication 310
pericardial 310
thymic 309
Cytarabine 24, 46, 47, 50, 52, 60, 80, 212, 230, 232, 258, 260, 261, 261f, 337
high-dose 46, 60, 64, 91, 93, 230, 239
Cytogenetic abnormalities 76, 163
Cytogenetic profile 148
Cytogenetic response 145, 150, 151
Cytokine
receptor-like factor 115, 116
release syndrome 11, 33
Cytomegalovirus 13, 161, 241, 280
Cytopenia 244, 255, 281
chronic 287
refractory 243
Cytoplasmic clusters 41
Cytoreduction 304
nonspecific 304, 306
Cytoreductive treatment 334
Cytosine arabinoside 57
high-dose 233
Cytotoxic chemotherapy 293, 314
D
Dacarbazine 222, 230, 336
Dasatinib 152
Daunorubicin 46, 52, 57, 66, 67, 93, 314
Decitabine 82
Dendritic cell 253
neoplasms 277
Deoxyribonucleic acid 305
Dexamethasone 27, 212, 230, 233, 305, 306, 314, 334
Dexrazoxane 67
Diabetes insipidus 277
Dialysis 333
Diffuse large B cell lymphoma 188, 295
management of 199
Disseminated intravascular coagulation 126, 127, 301, 302
Diuresis 296
Dizziness 139
Double hit lymphoma 209, 218
Down's syndrome 91, 93, 94, 249
Doxorubicin 25, 66, 222, 230, 314, 336
Drug toxicity 49, 241
Dysplasia, morphological 241
E
Ebstein-Barr virus 161, 280
Electrocardiogram 298
Electrolyte
abnormality 298
serum 298
Emperipolesis 273
Empirical anti-fungal therapy 327
Encephalopathy 33
Endobronchial mass 173
Endocrine 223, 271
abnormality 255
Endothelium thrombogenicity 127f
Enzymes, lysosomal 273
Eosinophilia 140
Epithelial mesenchymal transition 274
Epstein-Barr virus 208, 219, 241
role of 208
Erdheim-Chester disease 262, 268, 269f, 270f, 274
diagnosis of 270
pathogenesis of 274fc
Erythrocyte sedimentation rate 256
Erythroid 241
Etoposide 46, 52, 57, 212, 220, 222, 228230, 232, 233, 336
Exophthalmos 277
F
Familial platelet disorder 243
Febrile neutropenia 48, 292, 319, 323fc
Febuxostat 296, 297
Fertility 223
preservation 152f, 158
Fibrin degradation products 126f
Fibrinogen degradation product 127
Fibrinolysis, activation of 126f
Fine needle aspiration 336
cytology 4, 178f
Flow cytometry 21, 22, 75, 312
Fluconazole 328
Fludarabine 13, 24
cytarabine 60
Fludeoxyglucose 254, 260
Fludrabine cytarabine 46
Fluorescence in situ hybridization 2fc, 7, 21, 22, 102, 115, 141, 244
Fluorodeoxyglucose 173f, 266
qualitative 285
quantitative 285
Fluoroquinolones 48
Fungal infections 49, 338
G
Galactomannan 325
Ganglioneuroblastoma 310
Ganglioneuromas 310
Gemcitabine 228, 229, 234
Gemtuzumab 47
ozogamicin 46, 63
Germ cell tumor 309, 319
Giant cell 253
Glasgow coma scale 319
Glucose-6-phosphate dehydrogenase 297
Glycogen synthase kinase 274
Goiter, retrosternal 309
Gonadotropin 253
Graft versus host disease 13, 246
chronic 62, 65
Graham's patch repair 219
Gram-negative
bacilli 323
infection 324
Granulocytes 139f
colony-stimulating factor 46, 49, 60, 170, 198, 268, 328, 328
macrophage colony-stimulating factor 161, 162
monocyte-colony stimulating factor 268
proliferation of 139
transfusion 329, 338
Growth factors 253, 337
Growth failure 255
Growth retardation 262
Guillain-Barre syndrome 281
H
Headache 139
Hearing loss 262
Hemangioma 309, 310
Hematological disorders 240
Hematopoietic stem cell 252
transplantation 46, 47, 60, 63, 65, 73, 146, 150, 151, 162, 181, 198, 213, 247, 258, 259, 262, 328
indications of 153f
role of 287
Hemodialysis 333
intermittent 299
Hemoglobin 242
fetal 161
Hemoglobinuria, paroxysmal nocturnal 244
Hemorrhage 128
retinal 303
Hepatic toxicity 65
Hepatitis C virus 141
Herpesvirus 241
High methylation group 163
Histiocytic disorders 274, 278
Histiocytoses 275
cutaneous 277
malignant 277
revised classification of 268f
Histone
deacetylase 82
lysine methyltransferase 75
Hodgkin's disease 273
Hodgkin's international prognostic score 223
Hodgkin's lymphoma 182, 188, 219, 223, 226, 228, 229, 284, 336
refractory 219
Human immunodeficiency virus 208, 241, 280
Human leukocyte antigen 246, 268
Hybrid chemotherapy 79
Hydration 304
Hydrocortisone 314
Hydroureteronephrosis 272
Hydroxyurea 141, 304, 306
Hypercalcemia 16
Hyperdiploidy 15
Hyperhydration 295
Hyperkalemia 293, 294, 298, 332
Hyperleukocytosis 76, 139, 292, 301, 303, 334, 335
clinical features of 301
initial management of 305
pathophysiology of 301, 301fc
prognostic significance of 308
risk of 302
Hypernatremia 296
Hyperphosphatemia 293, 294, 298, 332
Hyperplasia, thymic 309
Hypersensitivity reaction 296
Hypertriglyceridemia 64
Hyperuricemia 293, 294, 332
Hypocalcemia 293, 294, 298, 332
Hyponatremia 295
hospital-acquired 296
Hypoplastic marrow 244
Hypothalamic syndromes 255
Hypothesis 252
I
Idarubicin 24f, 46
Ifosfamide 220, 228230, 234
Imatinib 145, 154
Immature lymphoid cells 205
Immune
dysregulation 252
suppression 285
thrombocytopenia 280
thrombocytopenic purpura 284
Immunoglobulin 4, 65, 207, 282
intravenous 218, 286
Immunohistochemistry 205f, 244
Immunophenotypes, leukemias associated 4
Immunophenotyping markers 41t
Immunotherapy 11
era of 12
Induction chemotherapy 28f
Infection 49
bacterial 241, 338
chronic 219
severe 316
Inflammatory myeloid neoplasm 270
Inflammatory myofibroblastic tumor 175
Inflammatory neoplastic disorder 252
Infliximab 272
Inherited bone marrow failure syndrome 240, 243, 244
Inotuzumab 11, 33
Intensification 43
chemotherapy 30f
Interferon-alpha 272
Interim maintenance chemotherapy 30f
Interleukin 116, 274, 282, 305
Intracranial tension 301
Intrathecal therapy 78
Iron accumulation 66
J
Janus kinase enzyme 116
Japanese pediatric leukemia 77
Jaundice 251
Juvenile myelomonocytic leukemia 140, 159161, 165, 244, 283
diagnosis of 161fc
diagnostic criteria of 160
management of 166
pathogenesis of 162
K
Karyotype
interpretation of 90
normal 245
Kidney
function tests 143
injury, acute 296
L
Lactate dehydrogenase 206, 210, 295
Langerhans cell histiocytosis 161, 251, 252, 256, 259, 262, 268, 319
laboratory evaluation in 255t
pathogenesis of 252
L-asparaginase 212
Lesions 266
Leukapheresis 140, 306, 335
indications of 140
therapeutic 334
Leukemia 74, 102, 140, 159161, 165, 214, 244, 283, 309, 332
acute 188
lymphoblastic 1, 7fc, 19, 23, 44, 69, 74, 75, 77, 79, 81, 93, 102, 115, 116, 139, 295, 302, 307, 319
lymphoid 125
megakaryoblastic 91, 94
myelogenous 47
myeloid 40, 41, 43fc, 46, 49, 58, 60, 68, 74, 90, 91, 165, 295, 301, 302, 305, 307, 319, 328
promyelocytic 126f, 127, 127f, 130
characteristics of 89
childhood acute lymphoblastic 2fc
chronic
myelocytic 243
myeloid 102, 138, 138f, 139, 146, 151, 273, 295, 302, 303, 305
infantile 74
lymphoma group 198
maintenance phase of 337
myeloid 79, 91, 93
phenotypic acute 40
presentation of 75
second 25
Leukemic cells 76
Leukemoid reaction 140
Leukocyte
adhesion defect 161
count 306
Leukocytosis 138f
Leukoproliferative disease 283
Leukostasis 302, 303
Levofloxacin 48
Lipid-Laden histiocytes 271
Lipoma 309, 310
Liposomal amphotericin B 327, 328
efficacy of 327
Liposomal daunorubicin 24, 46, 60
Liver 254, 255
dysfunction 51, 255
mild to moderate 51
transplantation 262
Lomustine 233
Lung 255, 272
bilateral 260f
Lymph node
abdominal 220f
enlargement 280
Lymphadenopathy 189fc, 278
infectious 309, 310
Lymphangioma 309, 310
Lymphohistiocytosis, hemophagocytic 268, 277, 280
Lymphoid cells, autoreactive 280
Lymphoma 209, 209f, 280, 308, 309, 332, 336
malignant 193
pediatric 190
study group 77
Lymphophagocytosis 281
Lymphoproliferative disorder 284
RAS-associated 284
M
Magnetic resonance imaging 128f, 256
Maintenance therapy 132
Malignancy
hematological 338
risk of 284
Malignant peripheral nerve sheath tumor 310
Malnutrition 52
Maximum intensity projection 220f
May-Grunwald Giemsa stained slides 19f
Mechanical cytoreduction 306
types of 306
Mediastinal mass 309, 311, 312
Megakaryocyte 241
Melphalan 81, 232
Mercaptopurine 297
Metabolic disorders 241
Metabolic response 213, 226, 228, 229
Metamyelocyte 138f, 140
Methotrexate 79, 210, 246
high-dose 78, 80
Methylation 163
group 163
Methylprednisolone 230, 239, 285, 314
Micromegakaryocytes 243, 245
Minimal disseminated disease 175177, 196
Minimal residual disease 1, 3, 7, 2124, 24f, 81, 93, 145, 176, 196
detection, methods for 3t
Minimally myelosuppressive chemotherapy 318
Mitogen activated protein kinase 252
Mitoxantrone 46, 47, 60, 80
Mixed lineage leukemia 77, 81, 247
Mixed-phenotype acute leukemia 41
Molecular pathway 100
Molecular remission 20, 43, 47, 154, 157
Molecular response 145
Molecular tests 271
Monocytosis 159f
Monotherapy 321
choice of 321
Multicolor flow cytometry 4
Multiple lytic lesions 266f
Multi-system disease 271
Myelocyte 140
Myelodysplastic syndrome 240, 242244, 246, 247, 249, 270
diagnosis of 245
low-risk 246
management of 249
Myeloperoxidase, intracellular 41
Myeloproliferative disorders 273
Myelosuppression 51
Myelosuppressive chemotherapy 318, 319
N
Natural killer cell 244
Neoplasms
myeloid 270
myeloproliferative 270
Nephrology, pediatric 299
Nephrotoxic drugs 294
Neuroblastoma 175, 188, 332
Neurodegeneration 253, 262
Neurotoxicity 33
Neutropenia 152, 182, 211, 242, 328
Next-generation sequencing 7, 21, 72
Nonhematological disorders 241
Non-Hodgkin's lymphoma 22, 188, 190, 206, 273, 284, 336
refractory 197
Non-Langerhans cell histiocytosis 266
O
Oligonucleotides, allele-specific 4
Oral phosphate binders 298
Orthopnea 311
Osteonecrosis 65
Osteopenia 65
Osteoporosis 65
Oxaliplatin 234
Ozogamicin 47
P
Papilledema 140, 303
Parathyroid
adenoma 309
hormone 143
Parvovirus 241
Peak expiratory flow rate 312
Pearson syndrome 241
Pericardial fluid examination 313
Peripheral blood 4, 156, 161, 301
smear 138f, 159f
Peripheral smear 87, 89, 312
Peritoneal dialysis 333
P-glycoprotein 25
Philadelphia chromosome 100, 111
molecular biology of 99
Phosphoprotein 175
Phosphorus 298, 315
Pleural fluid 313
Pneumocystis jiroveci 318
prophylaxis 28
Pneumonitis 262
Polydipsia 251, 255
Polyethylene glycol 27
Polymerase chain reaction 1, 4, 21, 141, 196, 253
Polyuria 251, 255
Posaconazole 328, 337
Positron emission tomography 173f, 228, 229, 254, 256, 260, 261, 266
Posterior reversible encephalopathy syndrome 153
Postrituximab 218
Potassium 298, 315
Prednisolone 222, 230, 258, 279, 336
Prednisone 210, 222
Priapism 140
Procarbazine 222, 336
Progressive disease 228, 229
Promyelocytes 138f
abnormal large 124f
Prophylaxis 48
Prothrombin fragment 126f
Prothrombotic factors, plasma levels of 126f
Proto-oncogene, function of 206
Pulmonary function tests 65
R
Radiotherapy 211, 226, 228, 229
Rapamycin 281
complex 274
Rasburicase 297
Rat sarcoma 283
Reed-Sternberg cells 231
Refractory disease 11, 176
Renal dysfunction 52, 294
Renal failure 332, 333
Renal replacement therapy 299
indications of 299
Resistant infections, high risk of 322
Respiratory distress 129, 254
Respiratory status 312
Retinoblastoma 319
Retro-orbital infiltration 271
Retroperitoneal lymph node 219
Reverse transcriptase polymerase chain reaction 7, 181, 115, 116
Rhabdomyolysis 262
Rhabdomyosarcoma 175, 188, 319
Rheumatic disease 241
Ribonucleic acid 115, 116
Rituximab 198, 212, 218, 233, 284
role of 233
use of 212
Rosai-Dorfman-Destombes disease 277, 278, 281
S
Salvage chemotherapy 73, 212
Seckel syndrome 240
Seizures 33, 332
development of 333
Sensorium 333
Serum glutamic
oxaloacetic transaminase 319
pyruvic transaminase 319
Sexual maturity rating 254
Short stature 255
Shwachman-Diamond syndrome 240
Sirolimus 282
Skin 255
rash 277, 296
Sodium 298, 315
Sperm cryopreservation 152
Spleen size 254
Splenectomy, role of 164
Stable disease 228, 229
Standard-dose salvage chemotherapy regimens 230
Staphylococcus aureus 140, 322
Stem cell 198
mobilization 231
rescue 221
transplant 24, 24f, 43, 179, 258
Steroids 284, 305, 314
high-dose 282
Streptococcus pneumoniae 140
Stridor 311
Sulfamethoxazole 28
Superior mediastinal syndrome 292, 310, 314, 335
Superior mediastinal syndrome, management of 335, 336
Superior vena cava syndrome 310, 314
Switch-tyrosine kinase inhibitor 149fc
Syndrome of inappropriate antidiuretic hormone secretion 295
Systemic lupus erythematosus 281
T
T-cell 3, 82
accumulate 281
disease 334
double-negative 281, 282
receptor 4, 282
therapy 33
Testicular leukemia 25
Testis 31
Thioguanine 93
Thiotepa 13
Threonine protein kinase 269
Thrombin antithrombin complex 126f
Thrombocytopenia 152, 159f, 242, 243, 335, 336
Thrombosis 128
Thymoma 309
Thyroid tumors 309
Thyroiditis 281
Thyrotropin 253
Tisagenlecleucel 11
Tissue, immunohistochemistry of 205f
Tocilizumab 272
Total body irradiation 61, 65, 181
Total leukocyte count 102, 115, 162
Total lymphocyte count 142
Touton giant cells 277
Toxicity, hematological 198
Trans-retinoic acid 334
Trimethoprim 28
Triphosphate metabolism 273
Triple hit lymphomas 209, 218
Tuberculosis 310
Tumor
biomarkers 313
bronchoscopic images of 172f
cell lysis 299
solid 332, 338
Tumor lysis syndrome 292, 293, 301, 302, 305
diagnosis of 293
management of 332
pathophysiology of 293fc
risk of 210
Tyrosine kinase 63
domain 148, 150, 151
gene 130
inhibitor 26, 116, 139, 146, 150, 151, 153, 272
U
Ultrasonography 256
Ultrasound-guided testicular fine needle aspirate cytology 19f
Umbilical cord blood 165
Uremia 293
Uric acid lowering agents 296
Urinalysis 317
Urinary tract infection 317
Urine
culture 317
output, monitoring of 298
Urokinase-type plasminogen activator 126f
Urticarial rash 281
Uveitis 281
V
Valvular disease 272
Varicella virus 241
Vascular cell adhesion molecule 305
Vascular endothelial growth factor 273
Ventricular dysfunction 336
Vinblastine 177, 222, 230, 258, 336
role of 179
single-agent 179
Vincristine 27, 78, 210, 222, 279, 336
Vinorelbine 228, 229
Vitamin D 143
Voriconazole 28, 328, 337
W
Weight gain 129
Wheezing 311
White blood
cell 77, 81, 244, 301, 307
count 7
X
Xanthelasma 277
Xanthogranuloma, juvenile 268, 277, 278
X-ray absorptiometry, dual energy 65
Z
Zoledronic acid 272
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Chapter Notes

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Acute Lymphoblastic Leukemia and Minimal Residual DiseaseCHAPTER 1

Gargi Das,
Rachna Seth
 
  1. What is the risk stratification of this child?
    As per the Indian Childhood Collaborative Leukemia (ICiCLe) group, the 7-year-old child has a nonbulky disease with TLC < 50,000/µL, no testicular and central nervous system (CNS) involvement, and a good prednisolone response, he was initially classified as a standard risk (SR) B-ALL.
  2. What is important in the FCM in this child?
    There are some markers that have been used for diagnosis (CD45, CD34, CD19, CD10, and cCD79a) along with some markers used to assist specifically for minimal residual disease (MRD) (CD58, CD81, CD38, and CD123, in this case). Each center may use their own set of markers, which are used to identify leukemia-associated immunophenotype (LAIP) during MRD assessment at end of induction/consolidation (EOI/EOC).
  3. Is there anything else required for the risk stratification?
    Patients of B-ALL should have a basic karyotype and FISH (fluorescence in situ hybridization) [with or without a polymerase chain reaction (PCR) analysis] prior to start of therapy. The main challenge is to decide the minimum/optimum molecular/cytogenetic analysis required in a low-income and middle-income country (LMIC), where cost is a constraint.2
    zoom view
    Flowchart 1: Three-probe FISH (fluorescence in situ hybridization) approach to detect recurrent cytogenetic abnormalities in childhood acute lymphoblastic leukemia (ALL).
    A study done by Tata Medical Center, Kolkata, reported that a three-probe FISH approach could provide a practical approach for risk-stratified therapy in childhood ALL. Flowchart 1 provides the approach. With this technique we can identify t(12;21), hyperdiploidy, iamp21, BCR/ABL1, and KMT2A rearrangements, which account for 60–70% of all known mutations in B-ALL.1 A PCR may be performed when these tests are not available. It is noteworthy that a PCR will not identify aneuploidies and non-AF4 KMT2A translocations.
  1. What is the interpretation of this MRD?
    As the residual blasts share LAIP with baseline blasts, we may consider this to be detectable MRD. Detailed definition of MRD will be explained in the subsequent sections.
  2. What is MRD?
    Minimal residual disease describes disease that is present at a level below the sensitivity of morphological detection. As it is found in the absence of clinical signs or symptoms, it is 3termed as “minimal”. With the advent of next-generation sequencing (NGS), a better term yet, would be “measurable residual disease”. An MRD which is not detectable is potentially compatible with cure.2
    In patients with ALL, the levels of MRD reflect the collective influence of leukemic cell genetics, microenvironment, host factors, and treatment efficacy on treatment response.
    The goals for an MRD assessment would be:
    • Providing prognostic information
    • Assessing effectiveness of therapy
    • Guidance for risk adjusted therapy
      • MRD detected: More or different therapy
      • Not detected: Less therapy needed, less toxicity
    • Distinguish early recovery from persistent disease
      • The concept of hematogones
    • Predicting early relapse.
      Minimal residual disease can be assessed post induction, consolidation, prior to transplant, and any time when there is a doubt of relapse.2
      Minimal residual disease assessment is typically performed on a BM specimen (first pull sample to avoid hemodilution). Peripheral blood affords a lower sensitivity for MRD detection as compared to BM (median 1.5 log lower sensitivity). This is mainly true for acute myeloid leukemia and B-ALL. For T-cell ALL (T-ALL), though the cell of origin comes from the BM, the maturation of T cells happens in the thymus, hence peripheral blood maybe used for T-ALL.3
  1. What are the different methodologies to detect MRD? What is the ideal methodology for detection of MRD in a low–middle-income setting?
    The various methods to detect MRD are described in Table 1.4
TABLE 1   Methods for minimal residual disease detection.
Method
Target
Applicability
Material
Sensitivity
Advantage
Disadvantage
MCFC
LAIPs/DfN
>90%
Cell suspension (PB, BM, FNAC)
6–8 Color: 10−4
  • Fast and easy to set up
  • Widely applicable
  • Observer dependent
  • Less sensitive
  • Standardization may vary with each institute
RQ-PCR
Recurrent fusion genes: 12;21, BCR-ABL1, KMT2A-AF4
30–40%
RNA/DNA
10-4/10-5
  • High sensitivity
  • Rapid and easy
  • Relatively easy
  • Stable throughout treatment
  • Limited applicability (target-negative in >50% of patients)
  • Relatively expensive
RQ-PCR
IG/TCR rearrangements
90–95%
RNA/DNA
10−4/10−5
  • High sensitivity
  • Good applicability
  • Well standardized
  • Dependent on ASO-primer
  • Laborious and time consuming
  • Affected by clonal evolution
  • Large amount of diagnostic DNA
  • Relatively expensive4
RQ-PCR
IG/TCR rearrangements
90–95%
RNA/DNA
10−4/10−5
  • High sensitivity
  • Good applicability
  • Well standardized
  • Dependent on ASO-primer
  • Laborious and time consuming
  • Affected by clonal evolution
  • Large amount of diagnostic DNA
  • Relatively expensive
Nextgeneration sequencing
IG/TCR gene rearrangements
>95%
DNA
10-4/10-6
  • High sensitivity
  • High applicability
  • Clonal evolution identified
  • Not dependent on ASO-prime
  • Not standardized
  • Complex bioinformatics analysis
  • Expensive
(ASO: allele-specific oligonucleotides; BM: bone marrow; DfN: different from normal; FNAC: fine needle aspiration cytology; IG: immunoglobulin; LIAPs: leukemia-associated immunophenotypes; MCFC: multicolor flow cytometry; PB: peripheral blood; RQ-PCR: real-time quantitative polymerase chain reaction; TCR: T-cell receptor) Source: Adapted from the table by Starza ID et al. Minimal residual disease in acute lymphoblastic leukemia: Technical and clinical advances. Front Oncol. 2019.
Newer techniques have been developed including next-generation FCM and droplet di !gital PCR (ddPCR) which are advances of already available techniques, however not commonly used around the world.
  1. What are the definitions related to MRD used commonly?5
    1. MRD negative: Undetectable MRD
    2. MRD low positive: Detectable MRD ≤ 10–4 [quantitative-PCR (qPCR)] or <0.01% [multicolor flow cytometry (MCFC)]
    3. MRD high positive: Detectable MRD ≥ 10–4 to <10–3 (qPCR) or 0 > 0.01 to <0.1% (MCFC)
    4. MRD very high positive: MRD ≥ 10–3 (qPCR) or >0.1% (MCFC).
  2. Is there any evidence comparing MCFC with PCR for MRD detection in B-ALL?
    In a study conducted by Bader et al. at all-time points, qPCR detected more MRD than MCFC. High/Very high MRD detection was equivalent using the two approaches (MCFC vs. 5qPCR, 15 vs. 16%); however, low-level MRD (<0.01% by MFC, <10–4 by qPCR) was detected prehematopoietic stem cell transplantation (HSCT) in only 2% of MCFC patients versus 28% of qPCR patients. But it was also noted that low versus undetectable MRD pre-HSCT did not alter the outcome; hence, the clinical relevance of detecting such low levels of MRD is unknown.6
  3. Is there any evidence comparing MCFC with NGS?
    The higher analytic sensitivity and lower false-negative rate of NGS over flow cytometry for MRD detection in pediatric B-ALL is known and has been studied in the past. NGS and MCFC showed similar 5-year event-free survival (EFS) and overall survival (OS) for MRD-positive and -negative patients using an MRD threshold of 0.01%. However, NGS identified around 40% more patients with MRD positivity at this threshold who had worse outcomes than MCFC MRD-negative patients. In addition, NGS identified 20% of SR patients without MRD at any detectable level who had excellent 5-year EFS (98.1%) and OS (100%), who may benefit from deintensification of therapy.7
    Though PCR and NGS are more sensitive, they are also more expensive and not universally present. MCFC have been around for a long time and is well standardized. Though definite training is required for MRD analysis by MCFC, it is the only method with extremely wide applicability and faster processing (turnaround time few hours in certain institutes).
    Poisson statistics describe precision in rare event analysis. For an adequate sensitivity and precision, to detect an abnormal population at 0.01% of the mononuclear cells (1/10,000):
    • Collect 250,000–1,000,000 events
    • >500,000 events collected for all MRD studies usually.
  1. What are the approaches for MRD detection by FCM?
    There are two main approaches for MRD assessment different from normal (DfN) and LAIP approach.8
    • LAIP approach: Defines certain CD markers at diagnosis and tracks these in subsequent samples as described in our case vignette. Each LAIP is present on both leukemic cells and normal nucleated BM cells (hematogones), but their pattern of expression vary. Maximum sensitivity is around 10–4–10–5. The major disadvantage is that if there is an instability of even one LAIP marker following treatment—MRD may be labeled as falsely “negative”.
    • DfN approach: This is based on the identification of aberrant differentiation/maturation profiles at follow-up and uses a fixed antibody panel. It is applied when:
      • Information from diagnosis is not available.
      • To detect new aberrancies, together with disappearance of diagnosis aberrancies, referred as “immunophenotype shifts”.
        • Emerges from leukemia evolution or clonal selection.
6The best method for detection of MRD is a “combination approach”. This allows for detection of new aberrancies emerging at follow-up, and monitoring patients when there is an absence of diagnostic information. The term “LAIP-based DfN approach” has been coined by the European Leukemia Network for this combined strategy.
  1. Do you think this child's initial risk stratification is correct?
    1. Role of bulky disease in ALL.
      The early studies of Berlin Frankfurt Munster (BFM) group, children's cancer group (CCG), and the pediatric oncology group (POG) used bulky disease in liver and spleen to define high-risk disease. But with advancements and more insight into the biology of ALL, molecular and cytogenetics, prednisolone response and MRD took over in the scheme of risk stratification. The ICiCLe group assigns children an intermediate risk if they present with bulky disease.
      Our child had presence of liver and spleen (though not fulfilling definitions for bulky disease as per ICiCLe) and did not receive anthracycline during induction. Despite having a good prednisolone response, child had a persistent MRD. Is it possible that the presence of extramedullary (EM) disease should have warranted anthracyclines during induction?
    2. Redefining high hyperdiploidy.
      Children with B-ALL with high hyperdiploidy account for 25–30% of cases and have a favorable prognosis. It is defined by “total chromosome number of 51–67 or by a DNA content ≥ 1.16, and by a characteristic karyotype pattern (gains of chromosomes X, 4, 6, 10, 14, 17, 18, and 21).” However, around 10% of children with B-ALL and high hyperdiploidy relapse. Previous studies have reported the good prognostic value of trisomies of chromosomes 4, 10, 17, and 18. The poor risk group is identified either by “the absence of both good-risk trisomies (+17, +18) or by the presence of only one of these good-risk trisomies and at least one of the poor-risk trisomies (+5, +20).” There was a significant difference in relapse rate, EFS and OS, hence this group may benefit from intensification of therapy.9
      The child in the vignette, had high hyperdiploidy, but the chromosomal involvement did not include the poor risk chromosome.
    3. Role of Philadelphia-like (Ph-like) ALL.
      The genomic landscape of ALL is ever expanding. Ph-like ALL is a unique subtype which has gained popularity over the last decade as they display a gene expression profile (GEP) like that of Ph-positive ALL, and frequently harbor IKZF1 alterations, but lacks the hallmark BCR-ABL1 oncoprotein. They are actually three times more common than Ph-positive ALL and comprise 10% of children with SR B-ALL and 15% of children with NCI high-risk B-ALL. It is seen more frequently in boys and are associated with adverse clinical features at presentation (initial TLC > 100,000/µL) and detectable MRD at the EOI therapy, notably due to the EBF1–PDGFRB fusion. Children with Ph-like ALL have an increased propensity to relapse and have outcomes which are inferior to KMT2A and BCR-ABL1 rearranged leukemias.107
      zoom view
      Flowchart 2: Suggested approach for testing for Philadelphia-like (Ph-like) acute lymphoblastic leukemia (ALL) in low-income and middle-income countries (LMICs).
      (FISH: fluorescence in situ hybridization; MRD: minimal residual disease; NGS: next-generation sequencing; RT-PCR: reverse transcription-polymerase chain reaction; WBC: white blood count)
      1. What are the Ph-like alterations?
        For the purpose of this chapter, we have divided Ph-like alterations into five distinct subgroups based on the type of cytokine receptor or kinase fusion present.10
        1. Rearrangements of CRLF2 (47%): Most prevalent in all age groups.
        2. ABL-class gene rearrangements (13%): Including genes like ABL1, ABL2, PDGFRB, and CSF1R.
        3. JAK2 and EPOR rearrangements (11%)
        4. Sequence mutations or deletions activating JAK-STAT or MAPK signaling pathways (13%): IL7R, FLT3, and IL2RB, activating mutations of JAK-STAT pathway (JAK1 and JAK3) and deletion of genes that encode negative regulators of the JAK-STAT pathway (SH2B3).
        5. Other rare kinase alterations: RAS pathway mutations (NRAS, KRAS, PTPN11, NF)
          Similar to Ph-positive ALL, a unifying hallmark of Ph-like ALL is the high frequency of IKZF1 alterations relative to BCR-ABL negative non-Ph-like ALL (68 vs. 16%).
      2. Who should we screen for Ph-like ALL? A basic stepwise approach can be taken as described in Flowchart 2.
      3. Any benefit for screening for Ph-like ALL?8
        Yes, we can target these genes with certain drugs like ABL kinases (imatinib/dasatinib) for ABL rearrangements, JAK inhibitors (ruxolitinib) for JAK2/EPOR rearrangements and other mutations affecting JAK signaling pathway and drugs targeting JAK-STAT, PI3K, mTOR, and BCL2 for CRLF2-rearranged leukemias.10
  1. How should we define complete remission (CR) in a child with B-ALL in the era of MRD?
    Complete remission is traditionally defined as meeting all of the following response criteria:
    • <5% blasts in the BM
    • Normal maturation of all cellular components in the BM
    • No EM disease (e.g., CNS, soft tissue disease)
    • Absolute neutrophil count (ANC) ≥ 1,000/µL
    • Platelets ≥ 100,000/µL
    • Transfusion independent.
      Complete remission with incomplete hematologic recovery (CRi) is defined as meeting all of the following response criteria:
    • <5% blasts in the BM
    • Normal maturation of all cellular components in the BM
    • No EM disease (e.g., CNS, soft tissue disease)
    • Transfusion independent (please note, if the physician documents transfusion dependence related to treatment and not the patient's underlying ALL, CR should be reported).
Primary induction failure: If a patient has never been in CR or CRi.
  1. There is a significant variation in defining CR and time point to define CR. More importantly, the definition of induction failure differs between trial consortiums. With growing knowledge of MRD, should the definition of CR undergo modification? Even definitions for relapse do not include MRD, should there be a modification in the definition?
In an international consensus of the Ponte-di-Legno Consortium, the definitions of CR and treatment failure (TF) were given.11
  • Definition of CR:
    • CR is to be assessed no earlier than EOI.
    • For CR, the following is required:
      • BM: M1 cytomorphology and/or MRD < 1%9
      • CNS: CNS1 status
      • Testes: Normal on clinical examination, or a negative biopsy if clinical examination is not considered normal.
      • EM: No evidence of leukemic infiltrates as evaluated clinically and by imaging; a preexisting leukemic mass (mediastinal mass included) must have decreased at least to one-third of the initial tumor volume.
      • It is recommended that CR assessment of BM should be performed by cytomorphology, followed by a standardized MRD method. Complementary methods including genetic analysis may also be used to verify CR achievement.
      • CNS status should be based on CSF cytomorphology (other methods such as MCFC or genetic analysis may be used in unclear cases), and clinical neurological examination, and CNS imaging in case of neurological clinical findings. Physical examination, imaging, or histologic examination of a tissue biopsy should be used for the evaluation of non-CNS EM disease.
  • Definition of TF:
    • Failure to achieve CR at a clearly predefined time point (EOI and EOC or other time points during intensification) should be considered as a TF event.
    • “There was progress toward a consensus that a TF event is to be defined no earlier than the EOC, because this would allow a patient not achieving CR by EOI to be offered a consolidation therapy with agents not given during induction in an effort to overcome blast resistance and potentially achieve CR. If such a patient still does not achieve CR after this risk-adapted consolidation phase, this could reasonably define a TF event.”
  1. Are there any risk factors for MRD to be detectable?
    Minimal residual disease has been defined as the single most important factor to predict relapse in ALL. The Italian Association of Pediatric Hematology and Oncology (AIEOP)-BFM study, confirmed the prognostic value of PCR-MRD in its multivariate analysis but also found that WBC count, TEL/AML1 status, and DNA index retain independent significant impact on the hazard of relapse.12 However, in most studies, MRD detectability overtakes the initial risk stratification and other prognostic factors in children with B-ALL. In a recent meta-analysis, it was shown that irrespective of the method used for detection, cutoff used (0.01 or 0.001%), the initial cytogenetics or phenotype of the child, or the time point of detection, a detectable MRD is associated with an increased risk of relapse.13
  2. What are the options for a B-ALL with detectable MRD following induction?
    The UK-ALL 2003 trial tested whether, clinical standard and intermediate-risk ALL who have persistent MRD at the EOI therapy benefit from augmented postremission therapy. They found a significantly improved EFS rate, though there were increased toxicity to methotrexate and L-asparaginase in the augmented arm. Though there was no significant improvement in OS, trends were toward improved survival.14 The classification of high-risk patients using MRD assessment differs with different consortiums. The UK-ALL group defined MRD high risk as those with an MRD level of 0.01% or higher at day 29 of induction. This identifies almost 40–60% of the entire cohort with an intermediate prognosis compared with a smaller high-risk 10group (<10%) associated with a much higher risk of relapse identified by other study groups (MRD > 1% at day 42 in the St Jude study or >0.05% at week 12 in the AIEOP-BFM study).14 Hence, in low–middle-income countries, where chances of cure following relapse are low, it is probably better to augment chemotherapy postinduction, along with providing good supportive care for the toxicities.
  1. What are the options for a B-ALL with detectable MRD after consolidation?
    As defined in the AIEOP-BFM 2000 study, the incidence of relapse in patients with detectable MRD postinduction depends on MRD postconsolidation. Patients with high MRD levels after induction but no detectable MRD after consolidation had a 5-year cumulative incidence of relapse of 20.7%, compared with 40.7% in patients with MRD still positive but at a level <10–3 after consolidation.12 Hence, it is reasonable to assume that patients with a poor MRD response after 2 months of therapy, despite rather favorable risk criteria may benefit from treatment intensification, like HSCT, to compensate for the MRD-derived high relapse risk. The UK-ALL group also found that persistent MRD following augmented consolidation therapy indicates a degree of chemotherapy refractoriness that might not overcome by further dose intensification of standard chemotherapy drugs. Therefore, in their current trial, UK-ALL 2011, patients who have persistent high-level MRD (>0.5%) after augmented consolidation therapy are candidates for treatment with novel agents followed by a first remission allogeneic transplant.14
  2. Is there any utility of doing an MRD analysis earlier (day 15/day 19) in B-ALL?
    The St Judes Total Therapy 15 study, conducted a day 19 MRD analysis and found that the 10-year EFS was significantly inferior for patients with MRD ≥ 1% on day 19 compared with that of patients having lower MRD levels: 69.2 versus 95.5% for the provisional low-risk group and 65.1 versus 82.9% for the provisional SR group. For the provisional low-risk patients, an MRD level of <1% on day 19 predicted a superior outcome, regardless of the MRD level on day 46, while in provisional SR patients with MRD < 1% on day 19, persistent MRD on day 46 tended to have an inferior 10-year EFS compared with those having a detectable MRD (72.7 vs. 84.0%, p = 0.06) after receiving the same postremission treatment for SR ALL.15
  3. What is the utility of sequential MRD assessment?
    It is debatable whether a patient who goes into MRD-negative status after induction requires sequential MRD assessment. The St Jude Total Therapy 15 study was the first clinical trial to use MRD levels prospectively during and after remission induction therapy to guide risk-directed treatment. MRD levels were measured on days 19 and 46 of induction, and on 11week 7 of continuation treatment. Additional MRD determinations were made on weeks 17, 48, and 120 (end of therapy). Among patients attaining MRD-negative status after remission induction, MRD reemerged in 4 of 382 studied on week 7, 1 of 448 on week 17, and 1 of 437 on week 48; all but 1 of these 6 patients died despite additional treatment. By contrast, relapse occurred in only 2 of the 11 patients who had decreasing MRD levels between the EOI and week 7 of continuation therapy and were treated with chemotherapy alone. Hence, sequential MRD monitoring after remission induction is warranted for patients with detectable MRD. In case of decreasing MRD, we may consider to treat these children with chemotherapy alone protocols (especially if MRD is detected at low levels).15
  1. If resource was not a constraint, is this child an ideal case for immunotherapy? What is the evidence for immunotherapy?
    Immunotherapy (blinatumomab, inotuzumab, and tisagenlecleucel) has a well-established role in relapsed and refractory ALL. All three treatments are most effective in patients with relatively low burden of disease and hence there is growing interest in these strategies for preventing relapse in MRD-positive patients.
    • Blinatumomab: This is a bispecific T-cell engager targeting CD 19 antigen on B cells. It is more effective in patients with lower burden of disease, making it a particularly promising agent for the treatment of MRD. Adult trials have proven an improvement in both EFS and OS in patients receiving blinatumomab for MRD eradication. MRD became a modifiable risk factor due to immunotherapy. The impact of immunotherapeutic clearance of MRD on survival is greatest when applied early in the disease course. Whether HSCT is required after blinatumomab is an open question as 25% of patients who achieved MRD negativity and did not receive any further therapy, remained in continuous CR after a median follow up of 24 months.16 The risk of transplant needs to be carefully weighed when making this decision. The COG has tested blinatumomab in pediatric ALL at first relapse17 and is currently using blinatumomab in frontline therapy of ALL.
    • Inotuzumab: Its role in relapsed and refractory ALL has been studied, leading to MRD eradication in 25–100% of patients.18 It is currently being studied as frontline treatment in the latest COG trials.
    • Chimeric antigen receptor (CAR) T cells: It is a form of adoptive immunotherapy which relies on the transfer of genetically modified effector cells to elicit an antileukemic immune response and therefore have the potential to persist in vivo, offering long-term disease control. The impact of various CAR constructs on MRD has been studied (mostly in the relapsed and refractory setting), with MRD negativity being achieved in 60–100% of patients.18
      Cytokine release syndrome (CRS) and neurologic events occur less frequently when immunotherapy is used for MRD than in patients with relapsed/refractory disease, likely due to the decreased disease burden.1812
  2. In the era of immunotherapy, what are the challenges in detection of MRD?
    T-cell mediated anti-CD19 therapy depletes normal and abnormal CD19 expressing B cells. The pattern of recovery differs from recovery post more traditional cytotoxic therapy. Moreover, there may be a selection of CD19 negative/CD22 positive clones and patients can relapse with CD19 positive or CD19 negative disease. In era of targeted therapy, single gating reagent may not be sufficient to identify normal population. Pattern of normal may change. Hence, we may need to use alternate blast antigen like CD34 or CD10/SSC or use alternate expression of B cells also to find blasts.
  1. What are factors to be kept in mind prior to transplant in a child with B-ALL?
    1. Is it important to achieve an MRD-negative status prior to transplant? If yes, what salvage regimens should we use?
      Presence of MRD prior to transplant predicts relapse and poor survival. It was shown that there is no impact on EFS if MRD is negative or low, but high/very high MRD pretransplant is associated with almost 40% risk of relapse. Post-transplant detectable MRD on day +180 and day +365 are associated with inferior survival rates as well and are considered to have a greater impact on survival than pretransplant MRD. If at all a patient has detectable MRD pretransplant and undergoes HSCT, it is important to see if these patients achieve a negative or low-MRD status post-transplant, otherwise survival is dismal.6 Hence, all efforts should be made to bring MRD to a low/undetectable state (preferably prior to transplant).
    2. What are the indications for transplant in pediatric ALL?
      The indications for transplant in pediatric ALL have evolved over time. According to the European Bone Marrow Transplant (EBMT) group, none of the baseline cytogenetic abnormalities warrants transplant in CR1. But, indications for transplant in CR1 may be guided by MRD. There is an “in general consensus” that detectable MRD following consolidation warrants a BM transplant. All T-ALL patients, and very early/early relapse warrants a transplant in CR2, and all cases of CR3 warrant a transplant provided they go into CR and have good performance status.19
13
  1. Describe HSCT in ALL.
    1. What is the preferred conditioning regimen?
      Most children receive a myeloablative conditioning regimen. This consists of total body irradiation (TBI) with etoposide or cyclophosphamide. If <4 years, busulfan (or treosulfan) + fludarabine ± Thiotepa.19 The famous FORUM trial compared TBI + etoposide with chemoconditioning using busulfan/treosulfan + fludarabine + thiotepa. They found an improvement in OS and EFS with decreased relapse rates in patients receiving TBI. They also found an increase in TRM with chemoconditioning regimens with similar rates of acute graft versus host disease (aGVHD).20
    2. What is the donor preference?
      An MSD is the best donor available for transplant as they lead to quicker engraftment, faster immune reconstitution, less severe infections, and less GVHD. A matched unrelated donor (MUD) has similar outcomes to MSD. But it is not clearly proven if a mismatched cord blood or a haploidentical donor (T-cell depleted or with use of post-transplant cyclophosphamide), can result in good outcomes in children with ALL.19 Younger donors are preferred with similar cytomegalovirus (CMV) status. If the recipient is a male, the EBMT recommends a male donor as compared to a female donor and as for source of stem cell, BM is preferred, however peripheral blood is more convenient and is also a safe option.19
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  1. Campana D. Minimal residual disease in acute lymphoblastic leukemia. Semin Hematol. 2009;46(1):100-6.
  1. Grimwade D, Freeman SD. Defining minimal residual disease in acute myeloid leukemia: Which platforms are ready for “prime time”? Blood. 2014;124(23):3345-55.
  1. Starza ID, Chiaretti S, De Propris MS, Elia L, Cavalli M, De Novi LA, et al. Minimal residual disease in acute lymphoblastic leukemia: Technical and clinical advances. Front Oncol. 2019;9:726.
  1. Kerst G, Kreyenberg H, Roth C, Well C, Dietz K, Coustan-Smith E, et al. Concurrent detection of minimal residual disease (MRD) in childhood acute lymphoblastic leukaemia by flow cytometry and real-time PCR. Br J Haematol. 2005;128(6):774-82.
  1. Bader P, Salzmann-Manrique E, Balduzzi A, Dalle JH, Woolfrey AE, Bar M, et al. More precisely defining risk peri-HCT in pediatric ALL: Pre- vs post-MRD measures, serial positivity, and risk modeling. Blood Adv. 2019;3(21):3393-405.
  1. 14Wood B, Wu D, Crossley B, Dai Y, Williamson D, Gawad C, et al. Measurable residual disease detection by high-throughput sequencing improves risk stratification for pediatric B-ALL. Blood. 2018;131(12):1350-9.
  1. Döhner H, Estey E, Grimwade D, Amadori S, Appelbaum FR, Büchner T, et al. Diagnosis and management of AML in adults: 2017 ELN recommendations from an international expert panel. Blood. 2017;129(4):424-47.
  1. Enshaei A, Vora A, Harrison CJ, Moppett J, Moorman AV. Defining low-risk high hyperdiploidy in patients with paediatric acute lymphoblastic leukaemia: a retrospective analysis of data from the UKALL97/99 and UKALL2003 clinical trials. Lancet Haematol. 2021;8(11):e828-39.
  1. Tran TH, Loh ML. Ph-like acute lymphoblastic leukemia. Hematology. 2016;2016(1):561-6.
  1. Buchmann S, Schrappe M, Baruchel A, Biondi A, Borowitz M, Campbell M, et al. Remission, treatment failure, and relapse in pediatric ALL: an international consensus of the Ponte-di-Legno Consortium. Blood. 2022;139(12):1785-93.
  1. Conter V, Bartram CR, Valsecchi MG, Schrauder A, Panzer-Grümayer R, Möricke A, et al. Molecular response to treatment redefines all prognostic factors in children and adolescents with B-cell precursor acute lymphoblastic leukemia: results in 3184 patients of the AIEOP-BFM ALL 2000 study. Blood. 2010;115(16):3206-14.
  1. Berry DA, Zhou S, Higley H, Mukundan L, Fu S, Reaman GH, et al. Association of minimal residual disease with clinical outcome in pediatric and adult acute lymphoblastic leukemia: a meta-analysis. JAMA Oncol. 2017;3(7):e170580.
  1. Vora A, Goulden N, Mitchell C, Hancock J, Hough R, Rowntree C, et al. Augmented post-remission therapy for a minimal residual disease-defined high-risk subgroup of children and young people with clinical standard-risk and intermediate-risk acute lymphoblastic leukaemia (UKALL 2003): A randomised controlled trial. Lancet Oncol. 2014;15(8):809-18.
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EXPERT OPINION
Vaskar Saha MBBS DCH MD FRCP FRCPath PhD
Head of Pediatric Hematology and Oncology at Tata Medical Center and
Director of the Tata Translational Cancer Research Centre, Kolkata
Professor of Pediatric Oncology at the University of Manchester, United Kingdom
  1. Despite being a SR ALL, with hyperdiploidy (good risk cytogenetics), our child had persistent MRD positivity? What do you think were the causes for this?
    High hyperdiploidy is defined as an increase in the modal chromosome number in leukemic blasts from 46 to between 51 and 67. The nonrandom gains most often affect X, 4, 6, 10, 14, 17, 18, and 21. In particular trisomies of +4, +6, +10, +17, and +18 are associated with good outcomes for children with B-cell precursor (BCP) ALL on current protocols. The best outcomes have been reported for patients with +17 and +18 or either +17 or +18 but no +5 or +20. Though this patient had an atypical high hyperdiploid karyotype, there were no additional poor risk features.
    Depending on the induction protocol, around 40% of patients with high hyperdiploid BCP-ALL can have MRD levels of >0.01% at the EOI. The majority will clear MRD at the EOC. In this patient, the EOI MRD level was 0.018%, so just above the cutoff. This is not unusual. The EOC MRD was reported to be 2.6%. This sudden rise in MRD is quite unusual. At this level, the child has moved from being in CR to not in CR, bringing into question the reliability of the MRD. The report as presented simply states that the cells detected were CD34+, CD10+, CD19+, CD81+ (dim), and CD58+. FCM-based MRD is dependent on (1) the time of the aspirate—this should be ideally taken as the marrow is recovering prior to the flurry of regenerating hematogones, (2) obtaining sufficient cells, ideally over 4 million, and (3) operator expertise in distinguishing hematogones from malignant blasts.
    Regenerating hematogones will express CD34, CD10, CD19, and CD58 as they progress from immaturity to maturity. Pre-B1 cells express dim CD45, CD34, CD19, and CD10 while pre-B2 cells have brighter CD45, CD19, and CD10 and partial CD20 but lack CD34. Pre-B1 and pre-B2 cells appear broadly distributed on CD20–CD10 and CD34–CD10 dot plots, while they form tight overlapping clusters. Mature B cells have negative to dim expression of CD10 and bright CD20. The most stable markers are reported to be CD73, CD44, and CD38, not included in this panel. CD58 is not considered to be a reliable marker for MRD evaluation. Normal hematogones do not have asynchronous expression of early and late antigens. To distinguish between these normal and the abnormal cells, one first needs to consider the comparative expression of these markers in normal and malignant cells. Evaluate the clusters of cells expressing the markers to identify and quantify the leukemic blast population.16
    In hindsight then, the EOI marrow aspirate was performed on time in an early regenerating marrow and the MRD report is possibly correct for this time point. With rapid disease clearance in consolidation, MRD assessment was possibly then done on a fully regenerated marrow and erroneously reported as positive. In such cases it is helpful to examine the marrow aspirate for cellularity and reconstitution. BFM high-risk blocks are intensively myelosuppressive with late marrow regeneration. The BFM recommends the use of granulocyte colony-stimulating factor (G-CSF) during these blocks, and this possibly could contribute to MRD negativity by FCM-based MRD.
  2. Is it possible that the presence of EM disease should have warranted anthracyclines during induction?
    As described in the report this child had multiple large cervical lymph nodes (largest 2 cm in size), with liver and spleen palpable 2 and 3 cm (nonbulky). All these are within expected presentations of BCP-ALL and are not considered independent risk factors requiring additional therapy.
  3. How do you manage unusual sites/unusual presentations in ALL-like bony lesions, hypercalcemia, etc.?
    These patients are usually managed on a case-by-case basis by the multidisciplinary team. Broadly, we do not consider electrolyte imbalances to be a risk factor. Unusual EM sites like bone or skin are rare. As there is no real consensus on how these patients should be treated, we usually treat these patients as high-risk, unless preexisting morbidity precludes this approach.
  4. In a resource-limited setting, considering the morbidity of transplant and the relative ease to procure some inhibitors, should we test for Ph-like ALL in all cases of ALL upfront or should we restrict it to those patients with MRD positivity or other high-risk clinical features?
    The cost of relapse is far more than the tests. High hyperdiploid ALL cells may rarely contain TCF3::PBX1, BCR::ABL1, ETV6::RUNX1, KMT2A rearrangements as well fusions typical of Ph-like ALL. Ph-like ALL can be identified in around 14% of SR ALL and associated with inferior EFS. Around 60% of Ph-like ALL have upregulated CRLF2, often because of a translocation and activation of the JAK-STAT pathway. At our center, all diagnostic samples are screened for CRLF2 expression by FCM. In patients whose blasts express CRLF2, we investigate for additional changes, e.g., P2RY8::CRLF2 or IGH::CRLF2 fusions. If present, we treat these patients as high risk. As these patients often have activation of the JAK-STAT pathway, they could potentially benefit as well from a JAK inhibitor, e.g., ruxolitinib. Ruxolitinib is expensive, toxic, and the benefits are as yet undetermined. For patients with a suboptimal response to treatment (EOI MRD > 1% or persistent MRD positivity at EOC), as in this case, we screen by FISH for ABL1, ABL2, and PDGFR-α rearrangements, as patients with fusions of these genes potentially benefit from adjuvant imatinib or dasatinib treatment. The proportion of Ph-like patients with ABL-class rearrangements though are fewer than those with aberrations in JAK-STAT signaling. Of late diagnostic samples from patients with suboptimal response are also being sequenced.17
  5. Is immunotherapy warranted upfront in children with MRD positivity postinduction/consolidation? Does the benefit outweigh cost?
    At our center, we have a donor program with Amgen providing free access to blinatumomab. All BCP-ALL patients with suboptimal response to therapy are offered blinatumomab and an allogeneic stem cell transplant (allo-SCT). As illustrated in this case and previously reported by us, while almost half of the eligible patients cannot afford allo-SCT they can receive blinatumomab. Achieving low/negative MRD prior to allo-SCT significantly decreases relapse post-SCT. Blinatumomab has also been shown to more effective than chemotherapy in decreasing MRD levels as well as decreasing relapse. So, immunotherapy prior to allo-SCT is beneficial. Most patients at our center have demonstrated a decrease/negativity in MRD after receiving blinatumomab. Further follow-up will be required to see if those who were not transplanted maintain remission.
  6. Does transplant in MRD-positive patients improve survival, or should we continue with chemotherapy?
    This depends on whether the patient is being treated as frontline or relapse, the time of relapse, immunophenotype, and cytogenetics. In BCP-ALL, MRD of <10 after the first phase of therapy (induction) is associated with the best outcomes in both de novo and relapsed ALL. These patients do not normally require a transplant. In the preimmunotherapy era MRD of ≥10–1 at the EOI or persistent of MRD beyond consolidation are associated with higher recurrence rates. For T-ALL, those with detectable MRD at the EOI but negative at the EOC have excellent outcomes.
    Does transplanting those with persistent MRD improve outcomes? Patients proceeding to allo-SCT, with MRD of 10–3 or lower prior to SCT have the best outcomes. This is perhaps best achieved in patients with persistent MRD with the aid of immunotherapy. The outcomes of patients with persistent or high MRD on frontline therapy who are transplanted does not differ significantly from patients who continue with chemotherapy. In the patients who were transplanted, high-risk relapse and EOI MRD ≥ 10–4, disease-free survival of 22% was reported; the numbers not transplanted were too few to comment. In very high-risk cytogenetic subtypes, e. g. Ph+ALL, potentially transplant in CR1 may be beneficial, though this benefit does not seem to translate to patients with a KMT2A rearrangement. Current evidence suggests a benefit for transplant in late medullary relapse BCP-ALL, but evidence of benefit of this strategy in other groups is equivocal.
  7. Would you have managed this child differently?
    At our center, we would have treated this patient as SR, based on the criteria provided. All patients who have a MRD of ≥10–4 are also tracked using PCR for Ig/TR rearrangements. We have previously reported the higher sensitivity and specificity of the PCR-based assay. Faced with a discordance between PCR and FCM, we would have proceeded to high-dose methotrexate and reassessed the marrow MRD again at this time point. Positivity by FCM but negative by PCR does occur and may indicate that the clones identified by the two techniques are different. In any case we would extend the FISH screen for such patients, and lately we also 18screen for IKZF1 deletions and additional copy number changes that identify IKZF1plus. Rarely a duplicated hypodiploid clone may mimic high hyperdiploidy. In such cases as this is due to duplication of a hypodiploid clone, two or four copies are seen of each chromosome and not trisomies as well as loss of heterozygosity. Most hypodiploid cases also have a mutated TP53 gene. When we suspect such a case, we perform additional tests for copy number alterations, loss of heterozygosity, and TP53 mutations.
    The BFM high-risk arm is associated with TRM of around 10% in the west and have not shown better outcomes in high-risk patients compared to other less intensive protocols, so we do not use this in patients with persistent MRD. Increasingly we now perform drug profiling on banked diagnostic samples to identify drugs likely to be effective and treat patients accordingly. After this therapy patients are offered blinatumomab and allo-SCT.