HMA-Venetoclax Induction in Newly Diagnosed AML

Standard of Care and Its Limitations The historical standard of care for young fit AML patients has been intensive induction chemotherapy with 7+3 (cytarabine 100 mg/m² Days 1-7 plus an anthracycline for 3 days). While CR rates of 60-80% are reported in clinical trial populations, real-world outcomes in LMIC settings are considerably inferior due to delays in diagnosis, limited access to molecular testing, high early mortality from infection, and inadequate supportive care infrastructure.

In Pakistan, the availability of 7+3 induction is widespread, but its administration is associated with prolonged periods of profound aplasia (typically 3-4 weeks), requiring inpatient intensive care support, broad-spectrum antifungal prophylaxis, and transfusion dependency. The cumulative cost of induction toxicity management frequently exceeds the cost of the chemotherapy itself, making 7+3 financially prohibitive for a significant fraction of the patient population.

Furthermore, access to anthracycline formulations (particularly liposomal daunorubicin or high-dose daunorubicin) that have shown superior outcomes in selected populations remains limited in the public sector in Pakistan. These constraints collectively create a compelling rationale to evaluate alternative, potentially less toxic, induction platforms that achieve equivalent or superior remission rates.

Rationale for HMA-Venetoclax in Young Fit AML Venetoclax, a selective BCL-2 inhibitor, induces apoptosis in AML blasts by disrupting mitochondrial-mediated survival signalling. In combination with hypomethylating agents (HMAs), venetoclax has demonstrated remarkable activity in older/unfit AML patients (VIALE-A trial: CR/CRi rate 66.4% vs 28.3% for AZA alone; median OS 14.7 vs 9.6 months). Subsequent mechanistic and clinical data have raised the hypothesis that HMA-VEN may be equally or more active in younger patients harbouring specific molecular vulnerabilities - notably NPM1 mutations, IDH1/2 mutations, and other BCL-2-dependent leukaemic subtypes.

Several emerging lines of evidence support extending HMA-VEN study to young fit patients. Firstly, pre-clinical data demonstrate that BCL-2 dependence is not age-restricted and may be determined by molecular subtype rather than patient fitness. Secondly, early phase and retrospective data from academic centres suggest that young patients with AML receiving AZA-VEN achieve CR/CRi rates of 60-75%, with MRD negativity rates of 30-50% and acceptable toxicity profiles notably different from 7+3 - specifically avoiding anthracycline-related cardiotoxicity. Thirdly, a shorter duration of neutropenia per cycle (typically 10-14 days) compared to 7+3 (21-28 days) represents a clinically meaningful advantage in resource-limited settings where supportive care capacity is finite.

Critically, achievement of remission and MRD negativity with AZA-VEN does not preclude subsequent allogeneic HSCT - the only proven curative modality for intermediate and high-risk AML - and several retrospective series confirm successful bridging to transplant following HMA-VEN induction with outcomes comparable to intensive chemotherapy-induced remissions. This trial is therefore designed as a complete treatment platform: AZA-VEN induction followed by risk-adapted post-remission therapy.

LMIC Context and Justification Pakistan is classified as a lower-middle-income country (World Bank). The majority of AML patients are treated at public sector tertiary hospitals where intensive chemotherapy-related early mortality rates range from 15-25% due to infection, organ toxicity, and limited intensive care capacity. Cost analysis of induction chemotherapy in LMIC settings demonstrates that HMA-VEN, while associated with a higher drug acquisition cost, may produce comparable or superior total expenditure profiles when hospitalisation, transfusion, antifungal therapy, and ICU costs are incorporated. Additionally, the oral formulation of venetoclax and the subcutaneous route of azacitidine administration simplify logistics and reduce infusion-related infrastructure requirements.

A critical ethical consideration is equitable access to curative-intent therapy. If HMA-VEN can achieve remission rates non-inferior to 7+3 in the young fit population with a more tolerable toxicity profile, it represents an important advance for patients in LMIC settings who may not survive intensive induction-associated aplasia. This study is therefore not simply a replication of Western data; it addresses an unmet need specific to the Pakistani and broader South Asian patient population.

Summary of Key Supporting Evidence Study Population Regimen CR/CRi Key Findings DiNardo et al. (VIALE-A, NEJM 2020) ND AML ≥75 yr or unfit AZA+VEN 66.4% OS benefit; pivotal registration trial Wei et al. (Lancet Oncol 2020) ND AML unfit LDAC+VEN 48% Randomised; VEN+LDAC superior to LDAC alone DiNardo et al. (Blood 2021) Retrospective, young AML AZA+VEN 64-72% Bridging to HSCT feasible; MRD neg in ~40% Lachowiez et al. (JCO 2022) ND AML fit ≤60 yr Intensive+VEN ~75% Phase Ib/II; enhanced depth of remission Maiti et al. (Blood Adv 2023) Retrospective young fit HMA+VEN 68% HSCT conversion 60%; OS comparable to 7+3 NUMS-AFBMTC Registry (2022) Institutional AML cohort, Pakistan 7+3 52% Early mortality 18%; anthracycline access limited

Inclusion criteria

Patients must satisfy ALL of the following criteria to be eligible for enrolment:

• Age 18-50 years (inclusive) at the time of enrolment
• Confirmed diagnosis of AML (non-APL) per WHO 2022 Classification: ≥20% blasts in bone marrow or peripheral blood, or documented leukaemia-defining cytogenetic abnormality regardless of blast count (e.g. t(8;21), inv(16), t(15;17) is excluded as APL). Diagnosis must be confirmed by bone marrow aspirate and/or biopsy with morphology, flow cytometry, and cytogenetics.
• Newly diagnosed AML: no prior cytotoxic therapy for AML (excluding hydroxyurea for blast cytoreduction, which is permitted for ≤7 days prior to enrolment)
• ECOG Performance Status 0-2
• Adequate end-organ function at screening (within 7 days of first study drug administration):

• Serum creatinine ≤2 × ULN or CrCl ≥40 mL/min (CKD-EPI formula)
• ALT and AST ≤3 × ULN (≤5 × ULN if attributed to hepatic leukaemic infiltration)
• Total bilirubin ≤1.5 × ULN (≤3 × ULN for Gilbert syndrome or hepatic leukaemic infiltration)
• LVEF ≥45% by echocardiography or MUGA (assessed within 28 days of enrolment)
• Willing and able to provide written informed consent (patient or legally authorised representative for patients with AMS at presentation)
• Willingness to comply with all study procedures, including bone marrow assessments, follow-up visits, and MRD monitoring
• For women of childbearing potential (WOCBP): negative serum or urine pregnancy test within 72 hours of Cycle 1 Day 1, and agreement to use effective contraception throughout study treatment and for 12 months after last dose
• For male patients with female partners of childbearing potential: agreement to use effective contraception and refrain from sperm donation throughout treatment and for 6 months after last dose 5.2 Exclusion Criteria

Patients will be excluded from participation if ANY of the following apply:

• Acute promyelocytic leukaemia (APL) [t(15;17); PML-RARA]: patients with APL must be referred for ATRA-based therapy as per institutional standard
• AML secondary to myeloproliferative neoplasm (MPN) in blast phase, where prior MPN was treated with ruxolitinib within 8 weeks of enrolment (due to drug interaction potential with venetoclax)
• Prior exposure to a BCL-2 inhibitor (venetoclax, navitoclax, or other) at any time
• Prior exposure to HMA therapy (azacitidine or decitabine) for a pre-existing MDS or MPN within 6 months of AML diagnosis
• Active, uncontrolled systemic infection at the time of enrolment that in the investigator's judgement would preclude initiation of cytotoxic therapy (note: controlled infection with appropriate antimicrobial therapy is not an exclusion)
• Known active hepatitis B virus (HBV) infection (HBsAg positive) without established antiviral prophylaxis; or active hepatitis C virus (HCV) infection with detectable viral load
• Known HIV infection with CD4 count <350 cells/μL or detectable viral load (HIV-positive patients with well-controlled disease on antiretroviral therapy may be enrolled after discussion with the Principal Investigator and Infectious Disease consultant)
• Cardiac exclusions:

• QTcF >480 ms on screening ECG
• Clinically significant and uncontrolled arrhythmia
• NYHA Class III-IV heart failure
• Acute coronary syndrome or stroke within 6 months of enrolment
• Malabsorption syndrome or other gastrointestinal condition that would significantly impair oral absorption of venetoclax
• Concomitant strong CYP3A4 inhibitors (e.g. ketoconazole, posaconazole, voriconazole, clarithromycin) or inducers (e.g. rifampicin, phenytoin, carbamazepine) that cannot be safely discontinued or dose-adjusted. (Note: azole antifungals require venetoclax dose reduction per label - see Section 7.4)
• Concurrent active malignancy requiring systemic therapy (patients with adequately treated non-melanoma skin cancer or carcinoma in situ of the cervix are eligible)
• Pregnancy or breastfeeding
• Participation in any other interventional clinical trial within 4 weeks of enrolment
• Any condition that, in the investigator's judgement, would compromise patient safety, protocol compliance, or the integrity of study data