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Acute Lymphoblastic Leukemia (ALL): A Comprehensive Hematologist's Reference

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1. DEFINITION

• Lymphoblastic lymphoma (LBL): When blasts predominantly form solid masses with <25% marrow involvement, the condition is termed LBL rather than ALL - though biologically these are the same disease.
• ~85% B-ALL, ~15% T-ALL (Robbins & Cotran Pathologic Basis of Disease, p. 556)

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2. EPIDEMIOLOGY

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3. PATHOGENESIS AND MOLECULAR BIOLOGY

Stepwise Oncogenesis

Key Molecular Pathways

• PAX5 mutations/deletions: 30% of B-ALL (critical B-cell transcription factor)
• IKZF1 (Ikaros) deletions: 25% of B-ALL; major adverse prognostic factor, hallmark of Ph-like ALL
• ETV6::RUNX1 (t(12;21)) fusion: 25% of pediatric B-ALL; favorable
• BCR::ABL1 (t(9;22)): constitutively active tyrosine kinase; frequency rises from 3-5% in children to ~50% in elderly adults
• KMT2A (MLL) rearrangements: t(4;11) in infants; very poor prognosis
• Hyperdiploidy (>50 chromosomes): ~25% of pediatric B-ALL; favorable (gains of chromosomes 4, 10, 17 especially good)
• Hypodiploidy (<44 chromosomes): <5%; very poor prognosis, near-haploidy especially bad

• NOTCH1 activating mutations: 50-70% of T-ALL; NOTCH1 is essential for T-cell development
• Translocations involving T-cell receptor loci (chromosomes 7 and 14)
• Early T-cell precursor (ETP) ALL: 10-15% of T-ALL; CD1a-/CD8-/CD5dim/myeloid antigen+; very high risk

• 10% pediatric, 20-30% young adults, ~25% adults
• IKZF1 deletion + kinase-activating rearrangements (CRLF2, JAK2, ABL1, PDGFRB, FLT3 fusions)
• CRLF2 overexpression is most common (~50% of Ph-like); JAK2 mutations co-occur
• Actionable targets for TKIs (dasatinib for ABL-class fusions, ruxolitinib for JAK2/CRLF2 rearrangements)
• Adverse prognosis; historically treated as standard risk but now recognized as high-risk

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4. WHO 2022 CLASSIFICATION

B-Lymphoblastic Leukemia/Lymphoma

T-Lymphoblastic Leukemia/Lymphoma

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5. IMMUNOPHENOTYPING

B-ALL Stages

T-ALL Markers

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6. CLINICAL FEATURES

Symptoms and Signs from Marrow Failure

• Anemia: Fatigue, pallor, exertional dyspnea, tachycardia (present in virtually all patients at diagnosis)
• Thrombocytopenia: Petechiae, ecchymoses, epistaxis, gingival bleeding, hemorrhage (~1/3 of patients)
• Neutropenia: Bacterial infections, fever (significant/life-threatening infections in ~1/3)

Extramedullary Infiltration (more common in ALL than AML)

• Lymphadenopathy: Generalized; cervical, axillary, inguinal nodes
• Hepatosplenomegaly: Common; can be massive
• Mediastinal/thymic mass: Classic in T-ALL (adolescent males); may cause superior vena cava syndrome, respiratory compromise, tracheal deviation - a medical emergency
• CNS involvement: Leukemic meningitis - headache, nausea, cranial nerve palsies, papilledema; occurs in 5-15% at diagnosis (higher in T-ALL, mature B-ALL, high WBC)
• Bone pain: Common especially in children; periosteal infiltration, medullary expansion; may mimic juvenile arthritis or osteomyelitis
• Testicular infiltration: Painless testicular enlargement; boys; a common sanctuary site
• Skin: Leukemia cutis - raised, nonpruritic papules/nodules (uncommon)
• Orbital/ocular: Proptosis in rare cases
• Hyperleukocytosis (WBC >100,000/µL): ~16% of ALL; risk of leukostasis, TLS

Laboratory Abnormalities at Diagnosis (Harrison's 22E data on 1273 cases)

• WBC <10 × 10⁹/L: 41%; 10-50: 31%; 50-100: 28%; >100: 16%
• Platelets <20 × 10⁹/L: 22%; 21-40: 22%; 41-100: 29%; >100: 27%
• Anemia virtually universal
• LDH elevated (marker of tumor burden)
• Uric acid elevated (tumor lysis risk)

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7. DIAGNOSTIC WORKUP

Bone Marrow Evaluation

• Aspirate + trephine biopsy: ≥20% lymphoblasts required (most present with >80%)
• Morphology: Lymphoblasts are small to medium, scant cytoplasm, condensed or dispersed chromatin, inconspicuous nucleoli (L1 FAB) or prominent nucleoli with irregular nuclear contours (L2 FAB); L3 (Burkitt-type) is now classified separately
• Cytochemistry: Lymphoblasts are TdT+, MPO-, Sudan black-; PAS may show block positivity (less used now)

Essential Diagnostic Tests at Diagnosis

1. Immunophenotyping by flow cytometry (4-6 color minimum): lineage assignment, stage, aberrant markers for MRD tracking
2. Conventional cytogenetics (karyotype): Ploidy status, major translocations
3. FISH panel: ETV6::RUNX1, BCR::ABL1, MYC, KMT2A rearrangements, hyperdiploidy probes
4. Molecular (RT-PCR/NGS): BCR::ABL1 isoform (p190 vs p210), IKZF1, PAX5, NOTCH1, CRLF2 expression
5. Ph-like ALL screening: CRLF2 by flow/FISH; kinase fusion panel by RNA sequencing (for adults, especially if IKZF1 deleted + CRLF2 overexpressed)
6. NGS panel (targeted or whole exome): comprehensive genomic profiling increasingly recommended
7. CSF cytology: Diagnostic LP before initiation of therapy (after platelets corrected); traumatic LP must be documented
8. Imaging: CT chest (mediastinal mass), CT/PET-CT if lymphoma-predominant presentation

WHO Response Definitions / MRD Assessment

• Multicolor flow cytometry (MFC): Sensitivity 10⁻⁴; widely available; tracks leukemia-associated immunophenotype (LAIP)
• Allele-specific oligonucleotide PCR (ASO-PCR): Sensitivity 10⁻⁵; tracks Ig/TCR gene rearrangements; labor intensive
• NGS (e.g., clonoSEQ): Sensitivity 10⁻⁶; tracks specific clonal rearrangements; FDA cleared; preferred for high-sensitivity monitoring
• Digital droplet PCR (ddPCR): Sensitivity 10⁻⁵-10⁻⁶; good for BCR::ABL1 monitoring

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8. RISK STRATIFICATION

Pediatric Risk Groups (COG/BFM framework)

Adult Risk Groups (ELN 2024 Recommendations)

• Age >35-40 years
• WBC >30×10⁹/L (B-ALL) or >100×10⁹/L (T-ALL)
• BCR::ABL1 (Ph+ ALL) - now partially mitigated by TKIs
• Ph-like (BCR::ABL1-like) with IKZF1 deletion
• KMT2A rearrangement
• Low hypodiploidy/near-haploidy
• TCF3::HLF
• MEF2D rearrangement
• iAMP21
• MRD positivity at end-induction (>0.01%) or end-consolidation (any detectable)
• T-ALL: ETP-ALL; MRD positive

• ETV6::RUNX1, high hyperdiploidy (pediatric only)
• DUX4 rearrangement (adult)
• NUTM1 (infants)
• MRD negativity (especially depth of negativity by NGS)

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9. TREATMENT PRINCIPLES AND OVERVIEW

1. Induction of remission (Weeks 1-4)
2. Post-remission therapy:
   • Consolidation (intensive short courses)
   • CNS-directed therapy
   • Maintenance (prolonged low-dose outpatient)
3. Transplant for high-risk patients in first remission, or at relapse

• Immunotherapy (blinatumomab, inotuzumab ozogamicin) into frontline regimens
• TKIs for Ph+ ALL
• MRD-guided treatment intensification/de-escalation
• CAR-T cell therapy for relapsed/refractory disease

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10. TREATMENT: PEDIATRIC ALL

Standard Protocols (COG, BFM, SJCRH)

• Vincristine 1.5 mg/m² IV weekly × 3-4 doses
• Prednisone 40-60 mg/m²/day PO × 28 days (or dexamethasone, which has superior CNS penetration)
• L-Asparaginase (PEG-asparaginase preferred): 2,500 IU/m² IM; enzyme depletion; cornerstone of pediatric protocols
• Daunorubicin or doxorubicin (high-risk patients)
• Intrathecal chemotherapy (MTX ± cytarabine ± hydrocortisone) at day 1, 8, 15, 29

• IT chemotherapy has replaced prophylactic cranial irradiation (12-18 Gy) in most cases
• Cranial irradiation reserved only for CNS-3 disease or certain very high-risk relapses
• Triple IT (MTX + cytarabine + hydrocortisone): COG standard; 10-18 doses during induction + consolidation

• Multiple blocks including: high-dose methotrexate (HDMTX) 2-5 g/m² with leucovorin rescue, 6-mercaptopurine, cyclophosphamide, cytarabine, etoposide
• MRD assessment drives intensification: MRD+ patients escalated to more intensive protocols or SCT

• Daily 6-mercaptopurine 75 mg/m² PO + weekly methotrexate 20 mg/m² PO
• Monthly vincristine + pulse dexamethasone (pulsed for first 1-2 years)
• TPMT/NUDT15 genotyping before starting 6-MP to guide dosing (risk of myelotoxicity)
• Total duration: ~2 years for girls, ~3 years for boys (testicular sanctuary)

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11. TREATMENT: ADOLESCENTS AND YOUNG ADULTS (AYA, Ages 15-39)

• Higher cumulative doses of asparaginase (PEG-asparaginase)
• Higher doses of vincristine, corticosteroids (dexamethasone preferred)
• Shorter but more intensive consolidation
• Longer maintenance
• Lower reliance on myelosuppressive anthracyclines

• Pediatric-inspired regimens with asparaginase are strongly recommended over traditional adult-oriented chemotherapy (e.g., Hyper-CVAD) for AYAs
• Allogeneic HSCT is NOT routinely recommended in first remission; reserved for higher-risk subsets or inadequate MRD response
• Targeted agents (TKIs for Ph+) increasingly supported in frontline
• Psychosocial support and fertility preservation are integral components

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12. TREATMENT: ADULT Ph-NEGATIVE B-ALL

Induction Regimens

• Cycles 1,3,5,7: Cyclophosphamide 300 mg/m² q12h × 3 days + vincristine 2 mg IV days 4,11 + doxorubicin 50 mg/m² day 4 + dexamethasone 40 mg/day days 1-4 and 11-14
• Cycles 2,4,6,8: High-dose MTX 1 g/m² day 1 + cytarabine 3 g/m² q12h × 4 doses days 2-3
• IT chemotherapy with each cycle (8 doses)
• CD20+, Ph-negative ALL: add rituximab (375 mg/m², 16-18 total doses) - improves OS (Goldman-Cecil Medicine)

• Incorporate higher doses of steroids, vincristine, asparaginase
• Increasingly preferred for patients up to age 60

Consolidation

• HDMTX ± cytarabine ± etoposide
• 4-8 cycles depending on protocol
• MRD assessment gates escalation decisions

The E1910 Trial - Landmark (NEJM 2024, PMID 39047240)

• Phase III RCT; adults 30-70 years with BCR::ABL1-negative BCP-ALL in MRD-negative CR
• Randomized to 4 cycles blinatumomab + 4 cycles consolidation vs consolidation alone
• Results: 3-year OS: 85% vs 68% (HR 0.41; p=0.002); 3-year RFS: 80% vs 64%
• Higher neuropsychiatric events in blinatumomab arm
• Practice-changing: Blinatumomab consolidation now standard of care even in MRD-negative adults

• GRAALL-R 2005 study showed OS benefit with addition of rituximab (8 infusions) to chemotherapy in CD20+ (>20%) adult B-ALL

Maintenance

• 6-mercaptopurine 50-75 mg/m²/day + MTX 20 mg/m² weekly (POMP: 6-MP, vincristine, MTX, prednisone)
• Duration: 18-24 months after consolidation
• Monthly vincristine + prednisone pulses in some protocols

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13. TREATMENT: Ph+ ALL (BCR::ABL1-POSITIVE)

TKI Selection (Frontline)

LANDMARK: Ponatinib vs Imatinib - Phase III RCT (JAMA 2024, PMID 38722621)

• 245 patients; all given reduced-intensity chemotherapy + ponatinib 30 mg vs imatinib 600 mg
• Primary endpoint (MRD-negative CR at end of cycle 3): Ponatinib 34.4% vs imatinib 16.7% (p=0.002)
• Median EFS: not reached (ponatinib) vs 29 months (imatinib)
• Arterial occlusive events: comparable (ponatinib 2.5%, imatinib 1.2%)
• Conclusion: Ponatinib superior to imatinib for frontline Ph+ ALL

Treatment Approaches for Ph+ ALL

• Hyper-CVAD + dasatinib or ponatinib
• Consolidation: HDMTX/cytarabine cycles
• Allogeneic HSCT in first remission (CR1) historically standard for all; now reconsidered if deep molecular remission achieved

• MDACC protocol: Blinatumomab + ponatinib (or dasatinib) - no cytotoxic chemotherapy
• Phase II results: 5-year OS >70%; MRD negativity in >90%
• Particularly suitable for older patients, those unfit for intensive chemotherapy
• The GIMEMA LAL2116 D-ALBA study (dasatinib + blinatumomab): CR rate >98%, CMR in >60%

• Increased IT doses (12 vs 8) after TKI incorporation reduced CNS relapse rate (Hyper-CVAD data)
• TKIs (dasatinib especially) have CNS penetration but are insufficient alone

• Still recommended for most patients in CR1 (especially if MRD+ or incomplete molecular response)
• Patients achieving sustained CMR (MRD negativity by NGS ≥10⁻⁶) may avoid HSCT on investigational protocols; not yet standard practice
• ELN 2024: HSCT remains the consolidation of choice for Ph+ ALL in CR1 unless contraindicated

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14. TREATMENT: Ph-LIKE (BCR::ABL1-LIKE) ALL

• Identified by gene expression profiling or targeted sequencing
• ABL-class fusions (ABL1, ABL2, PDGFRA, PDGFRB, CSF1R): respond to dasatinib or imatinib
• JAK pathway alterations (JAK2 fusions, EPOR rearrangements, CRLF2 fusions): may respond to ruxolitinib or other JAK inhibitors
• CRLF2 overexpression ± JAK mutations: add ruxolitinib to chemotherapy backbone (under investigation)
• Current ELN 2024 recommendation: include targeted TKI based on molecular profiling; enroll in clinical trials whenever possible

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15. TREATMENT: T-CELL ALL

Standard Approach

• Multiagent chemotherapy backbone (Hyper-CVAD, BFM, pediatric-inspired)
• Nelarabine (purine nucleoside analog, T-cell specific): approved for relapsed/refractory T-ALL; CR rate ~30% as single agent; now incorporated into frontline pediatric T-ALL protocols (COG AALL0434)
• Dexamethasone preferred over prednisone (superior CNS penetration and anti-leukemic activity)
• HDMTX for CNS prophylaxis

ETP-ALL

• Distinct subset: stem cell/myeloid phenotype (CD1a-, CD8-, CD5 dim, CD34+, CD117+, CD13+, CD33+)
• Poor response to standard T-ALL therapy
• DNMT3A, IDH1/2, FLT3 mutations frequent - targetable
• Allogeneic HSCT in CR1 recommended for ETP-ALL
• Venetoclax (BCL-2 inhibitor): preclinical and early clinical activity in ETP-ALL; under investigation
• Base-edited CAR7 T cells for T-ALL: Phase I data in NEJM 2026 (Chiesa et al., PMID 41363805) - fratricide-resistant allogeneic CAR7 T cells demonstrated responses in pediatric T-ALL

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16. CNS-DIRECTED THERAPY

Risk Classification

• CNS-1: No blasts on LP cytospin
• CNS-2: <5 WBC/µL, blasts present on cytospin
• CNS-3: ≥5 WBC/µL with blasts, OR cranial nerve palsy, OR brain/eye/spinal cord involvement

Prophylaxis and Treatment

• IT chemotherapy is the cornerstone; most modern protocols use 10-24 doses of IT therapy (MTX alone or triple IT)
• Prophylactic cranial radiation (12-18 Gy) eliminated from most protocols - late effects include neurocognitive deficits, secondary malignancies, endocrinopathies
• CNS-3 disease at diagnosis: IT + systemic intensification; radiation (24 Gy cranial ± 15 Gy spinal) still used in some high-risk scenarios
• Isolated CNS relapse: Systemic + intrathecal reinduction + cranial radiation; regarded as harbinger of systemic relapse

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17. IMMUNOTHERAPY: BLINATUMOMAB

• Relapsed/refractory B-ALL (adults and children)
• MRD-positive B-ALL in CR (FDA approved 2018)
• Now moving into frontline consolidation (post-E1910)

• Cytokine release syndrome (CRS): Usually grade 1-2; premedicate with dexamethasone
• Neurotoxicity: Confusion, encephalopathy, seizures (ICANS-like); step-1 interruption if grade ≥3
• Tumor lysis syndrome

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18. IMMUNOTHERAPY: INOTUZUMAB OZOGAMICIN (InO)

• Alliance A041703 (older patients ≥60): InO induction → blinatumomab consolidation: 96% ORR; bridging to transplant feasible
• INITIAL-1 study (>55 years): Fractionated InO → chemotherapy: 100% CR; 3-yr OS 73%
• EWALL-INO (>55 years): InO-based induction → chemotherapy: 90% CR/CRi

• Risk 10-15% overall; increases with prior alkylating exposure and if proceeding to HSCT
• Use ursodiol prophylaxis, avoid busulfan-conditioning, allow 2-month gap before HSCT
• Fatal SOS occurs in ~2% of transplanted patients

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19. CAR T-CELL THERAPY

CD19-directed CAR T (B-ALL)

CD22-directed CAR T

• CD22 CAR T: Active in CD19-dim/negative relapse (post-CD19 therapy)
• Dual CD19+CD22 CAR: Reduces antigen escape

T-ALL CAR T Challenges

• CD7 and CD2 antigens expressed on normal T cells → fratricide
• Base-edited CAR7 (NEJM 2026, PMID 41363805): Universal allogeneic T cells with gene editing to prevent fratricide; Phase I pediatric T-ALL: responses in refractory patients
• Fratricide-resistant CD7-CAR T (Nat Med 2024, PMID 39227445): Engineering strategies to overcome T-cell fratricide

CAR T + Transplant

• Allogeneic HSCT after CAR T-induced remission remains standard for eligible patients
• ASH 2026 AYA R/R guidelines: CAR-T or blinatumomab/InO preferred over chemotherapy for reinduction, followed by allo-HSCT for consolidation

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20. ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION (HSCT)

Indications

• Standard: Ph+ ALL in CR1 (unless exceptional molecular response); high-risk Ph-negative ALL in CR1 (high-risk cytogenetics, MRD+ after consolidation, ETP-ALL); all relapsed ALL in CR2+
• Debated: Intermediate-risk adult B-ALL in CR1 (MRD-guided decisions increasingly used)
• Not standard: Pediatric low/standard risk in CR1; AYAs per ASH 2026 unless high-risk features

Conditioning

• Myeloablative: TBI (12 Gy) + cyclophosphamide (gold standard for ALL) or busulfan + cyclophosphamide; TBI superior to busulfan in most ALL studies
• Reduced intensity (RIC): For older/comorbid patients; higher relapse rate, lower TRM

Donor Selection

• HLA-matched sibling: Gold standard
• Matched unrelated donor (MUD): Comparable outcomes
• Haploidentical (PTCy-based): Expanding option; comparable 3-year outcomes vs MUD in multiple studies
• Cord blood: Less used now; slower engraftment, higher TRM

GVL Effect

• Graft-versus-leukemia mediates anti-ALL activity; particularly important for relapse prevention
• DLI (donor lymphocyte infusion) may rescue molecular relapse post-HSCT

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21. TREATMENT OF RELAPSED/REFRACTORY ALL

Site and Timing of Relapse

• Most relapses: within 2 years, in bone marrow
• Early relapse (<18 months from CR): Extremely poor prognosis
• Late relapse (>36 months from CR): Better salvage rates

Salvage Approach (ASH 2026 AYA R/R Guidelines; ELN 2024)

1. Blinatumomab (CD19+): CR rate ~30-40% in heavily pretreated; ~70-80% in first relapse; preferred as initial salvage over chemotherapy per ASH 2026
2. Inotuzumab ozogamicin (CD22+): CR rate 80% in R/R (INO-VATE); preferred over chemotherapy if CD22+
3. CAR T-cell therapy: Preferred if blinatumomab/InO available; deepest and most durable responses
4. Conventional salvage chemotherapy (CLAG-M, FLAG-IDA, VDT-PACE, clofarabine): Reserved if no access to immunotherapy; lower CR rates, more toxicity
5. Allogeneic HSCT: Consolidation in CR2; still recommended for eligible patients achieving remission

• Nelarabine: CR ~30% single agent; backbone for T-ALL salvage
• Cyclophosphamide + etoposide ± nelarabine
• CAR7 T cells: Investigational but promising (NEJM 2026)
• Allogeneic HSCT for eligible patients in remission

• CD19-negative relapse after blinatumomab/CD19-CAR-T: Switch to CD22-directed therapy (InO or CD22-CAR-T)
• CD22-negative relapse after InO: Switch to CD19-directed therapy
• Bispecific CAR T (dual CD19+CD22) or novel antigens (CD38, CD123, TSLPR) under investigation
• Review article on post-immunotherapy relapse (Blood 2025, PMID 39046821)

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22. TREATMENT OF SPECIFIC POPULATIONS

Older Adults (≥60 years)

• Standard intensive chemotherapy poorly tolerated; higher TRM
• Preferred approach: Low-intensity chemotherapy + immunotherapy backbone
  • InO induction → blinatumomab consolidation + POMP maintenance (Alliance A041703)
  • SWOG 1318: Blinatumomab-based induction in ≥65: CR/CRi 66%; 3-yr OS 37%
  • GMALL BOLD: Blinatumomab + low-intensity chemo: MRD negativity 82%
• TKI + blinatumomab (without chemotherapy) for Ph+ older patients
• CAR-T trial enrollment encouraged

Infants with KMT2A-rearranged ALL

• Extremely poor prognosis with standard chemotherapy (3-yr OS ~25-35%)
• Blinatumomab addition (InFant trial, NEJM 2023, PMID 37099340): Improved MRD negativity and early survival data - paradigm shifting
• COG AALL0434 and successor protocols incorporate blinatumomab

CNS Disease at Diagnosis

• CNS-2: Continue standard IT + systemic therapy
• CNS-3: Intensified IT, systemic therapy; cranial radiation (24 Gy) may be needed; steroids acutely for raised ICP

Pregnancy-Associated ALL

• First trimester: Consider termination (high fetal risk from teratogenic drugs)
• Second/third trimester: Daunorubicin, vincristine, L-asparaginase relatively safer
• Avoid: MTX, 6-MP in first trimester; IT therapy after 20 weeks
• Multidisciplinary management essential

Down Syndrome ALL

• Generally favorable genetics (hyperdiploidy, ETV6::RUNX1 common)
• Higher treatment-related toxicity; dose reductions often needed
• Excellent outcomes with reduced-toxicity protocols (COG)

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23. SUPPORTIVE CARE

Tumor Lysis Syndrome (TLS) Prevention

• Uric acid control: Allopurinol (mild-moderate risk) or rasburicase 0.2 mg/kg (high WBC, high risk - phase III data: superior uric acid control)
• Aggressive hydration (3 L/m²/day) during induction
• Electrolyte monitoring every 4-6 hours; correct K+, phosphate, Ca2+

Infection Prophylaxis

• Antibacterial: Fluoroquinolone prophylaxis during neutropenia (levofloxacin/ciprofloxacin)
• Antifungal: Azole prophylaxis (fluconazole/voriconazole) during induction/consolidation
• Pneumocystis jirovecii: TMP-SMX or alternatives throughout therapy (except during MTX weeks)
• Antiviral: Acyclovir for HSV/VZV; consider CMV monitoring post-HSCT

L-Asparaginase Toxicities (critical to manage)

• Hypersensitivity/silent inactivation: Monitor with nadir asparaginase activity levels; switch formulation (E. coli → Erwinia) if allergic
• Pancreatitis: Hold asparaginase; lipase monitoring; grade 3-4 pancreatitis: permanent discontinuation
• Coagulopathy: Hypofibrinogenemia, decreased AT-III; monitor fibrinogen; replace with FFP/cryoprecipitate
• DVT/Thrombosis: Risk up to 10%; consider prophylactic anticoagulation in high-risk patients
• Hyperglycemia: Insulin management; dexamethasone synergizes

Vincristine Toxicity

• Peripheral neuropathy: Dose-reduce for grade 2+ motor neuropathy
• SIADH: Monitor sodium
• Constipation: Prophylactic stool softeners

Anthracycline Cardiotoxicity

• Cumulative dose monitoring (dexrazoxane in pediatric protocols ≥100 mg/m²)
• Baseline and follow-up echocardiography; LVEF monitoring

Corticosteroid Toxicities

• Avascular necrosis: Especially adolescents on high-dose dexamethasone (MRI hips/knees if symptomatic)
• Hyperglycemia, hypertension, behavioral changes
• Bone health: Vitamin D + calcium supplementation; DEXA monitoring

GVHD Prophylaxis (post-HSCT)

• Standard: Tacrolimus + short-course MTX, or tacrolimus + MMF
• Haploidentical: Post-transplant cyclophosphamide (PTCy) Day+3/4 + tacrolimus + MMF

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24. PROGNOSIS

Key Prognostic Factors

Overall Survival Benchmarks

• Pediatric (children 1-18): 5-year OS ~90%
• AYA (18-39): 5-year OS ~65-75% (with pediatric-inspired protocols)
• Adult (40-59): 5-year OS ~40-50% (improving with immunotherapy integration)
• Adult (≥60): 5-year OS <20% (improving with InO + blinatumomab regimens)
• Ph+ ALL: 5-year OS >80% (with TKI + immunotherapy)
• Relapsed ALL: 5-year OS 5-20% (improving with immunotherapy/CAR-T)

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25. LANDMARK CLINICAL TRIALS SUMMARY

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26. CURRENT FRONTLINE PROTOCOLS IN BRIEF

Key Named Protocols

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27. MONITORING AND FOLLOW-UP

• CBC with differential: 2-3× weekly during induction; weekly during consolidation; monthly during maintenance
• Bone marrow assessment: Day 14-15 induction (optional), Day 28-29 end-induction (mandatory), Day 56-70 end-consolidation, then every 3 months during consolidation
• MRD assessment: End-induction, end-consolidation (ideally after each consolidation cycle in high-risk); monitor during maintenance
• Renal and hepatic function: Before each cycle
• BCR::ABL1 quantification (Ph+ ALL): Monthly during treatment and after HSCT (IS scale by RT-qPCR)
• Asparaginase activity levels and anti-asparaginase antibody titers (when applicable)
• Echocardiography: Baseline; repeat after cumulative anthracycline dose ≥200 mg/m²

• CBC every 3 months × 2 years, then every 6 months × 3 years, then annually
• Bone marrow: At relapse signs only (not routine in molecular remission)
• Late-effects monitoring: Neurocognitive testing (cranial irradiation history), endocrine function, bone density, secondary malignancy surveillance
• Fertility counseling and referral before treatment begins

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28. EMERGING THERAPIES AND FUTURE DIRECTIONS

• Venetoclax in ETP-ALL and as combination partner (BCL-2 overexpressed in many B-ALL subtypes)
• Navitoclax (BCL-2/BCL-XL inhibitor): Combinations with chemotherapy
• Asciminib (STAMP inhibitor): For T315I+ Ph+ ALL; combination trials ongoing
• JAK inhibitors (ruxolitinib, baricitinib): Ph-like ALL with JAK pathway alterations
• MEK inhibitors: For RAS-mutated ALL
• Bispecific antibodies: Flotetuzumab (CD123 × CD3); MEDI3622 (CD22 × CD3); tandem BiTE approaches
• Antibody-drug conjugates: Anti-CD22-DM4; anti-CD38 conjugates
• Allogeneic universal CAR-T (base-edited, CRISPR-edited): Overcoming manufacturing time and HLA barriers
• MRD-guided treatment cessation: Prospective trials to safely stop therapy in deep molecular remission (NGS-based)
• Epigenetic therapies: HDAC inhibitors, hypomethylating agents (azacitidine/decitabine) in relapsed settings

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Sources and Key References

• Robbins, Cotran & Kumar - Pathologic Basis of Disease, 10th ed., Chapter 13 (Lymphoid Neoplasms)
• Goldman-Cecil Medicine, 27th ed. (International Edition), Chapter 168 (Acute Leukemias)
• Harrison's Principles of Internal Medicine, 22nd ed. (2025), Chapter 111 (ALL)
• Quick Compendium of Clinical Pathology, 5th ed., Section 4.3.2-4.3.7 (ALL immunophenotyping & genetics)
• Henry's Clinical Diagnosis and Management by Laboratory Methods (ALL MRD section)

• ELN 2024 Diagnosis & Prognostic Guidelines (Blood, Gökbuget et al.) - PMID 38295337
• ELN 2024 Management Guidelines (Blood, Gökbuget et al.) - PMID 38306595
• NCCN ALL v2.2024 (JNCCN, Shah et al.) - PMID 39413812
• NCCN Pediatric ALL v2.2025 (JNCCN, Inaba et al.) - PMID 39938467
• ASH 2026 AYA Frontline Guidelines (Blood Adv, DuVall et al.) - PMID 41670627
• ASH 2026 AYA R/R Guidelines (Blood Adv, O'Dwyer et al.) - PMID 41670624

• E1910 - Blinatumomab in MRD-neg adult ALL (NEJM 2024, Litzow et al.) - PMID 39047240
• PhALLCON - Ponatinib vs Imatinib frontline Ph+ ALL (JAMA 2024, Jabbour et al.) - PMID 38722621
• FELIX - Obecabtagene autoleucel in adult R/R B-ALL (NEJM 2024, Roddie et al.) - PMID 39602653
• InFant - Blinatumomab in infant ALL (NEJM 2023, van der Sluis et al.) - PMID 37099340
• Kantarjian & Jabbour - Adult ALL 2025 Update (AJH 2025) - PMID 40377367