Acute Myeloid Leukemia (AML) represents one of the most aggressive and formidable hematologic malignancies, characterized by rapid proliferation of abnormal myeloid cells in the bone marrow and peripheral blood. Despite advances in oncology, patients for whom AML relapses or demonstrates refractoriness to standard intensive chemotherapy regimens face grim prognoses. The disease’s aggressive nature and propensity to evade conventional treatments severely limit their options, and the likelihood of achieving long-term remission diminishes considerably once initial therapies fail.
In a groundbreaking development at Dresden University Hospital and the Faculty of Medicine at the Technical University of Dresden (TUD), researchers led by Prof. Christoph Röllig and Dr. Leo Ruhnke have unveiled a promising new treatment strategy designed to improve outcomes for patients with relapsed or refractory AML. Central to this innovation is the integration of the BCL2 inhibitor venetoclax with established high-dose chemotherapy agents cytarabine and mitoxantrone—an approach tested rigorously in the multicenter, early phase 1/2 RELAX trial, a pioneering effort in AML salvage therapy.
Relapsed or refractory AML patients often require a bridge to a potentially curative allogeneic stem cell transplant. However, securing such an opportunity is encumbered by the disease’s resistance to salvage chemotherapy, rendering the conventional standard therapy (combining cytarabine and mitoxantrone, known as HAM) only partially effective. Historically, complete remission rates post-salvage therapy hover around 40%, a statistic that underscores the urgent need for more efficacious regimens targeting these high-risk patients.
The RELAX study’s hypothesis was grounded in exploiting venetoclax’s mechanism of action—targeting the anti-apoptotic protein BCL2, which is often overexpressed in AML cells, thereby enabling their survival against chemotherapy. By inhibiting BCL2, venetoclax sensitizes leukemic blasts to cytotoxic insults. Initial phases of the RELAX trial focused on the tolerability and safety profile of the HAM-Ven combination, carefully monitoring dose-limiting toxicities and pharmacokinetic interactions, which then paved the way for evaluating clinical efficacy with larger patient cohorts across German and Austrian treatment centers.
Study outcomes herald a noteworthy clinical breakthrough: remission rates soared to approximately 75% in patients receiving the HAM-Ven regimen, nearly doubling those historically achieved with HAM alone. This increase is particularly significant given the inclusion of patients harboring adverse genetic mutations linked with notoriously treatment-resistant AML phenotypes. Moreover, the ability for the majority of these patients to proceed to stem cell transplantation dramatically improves their long-term survival prospects, underscoring the regimen’s potential to shift the evolving standard of care.
Prof. Martin Bornhäuser, a distinguished expert and director at Medical Clinic I in Dresden, emphasized the wider implications of these findings. He noted the important synergy between academic clinical research and pharmaceutical partnerships, exemplified by AbbVie’s substantial support and supply of venetoclax. This collaboration not only facilitated the clinical trial but also exemplifies a model of translational research where cutting-edge scientific insight accelerates tangible patient benefits.
Concurrently, the investigative team has expanded its scope beyond the initial trial, analyzing data from over 150 additional patients treated with HAM-Ven outside the formal study context in German tertiary centers. Preliminary data reinforce the promising efficacy and manageable safety profile observed during the trial phase, suggesting that this therapeutic approach is scalable within real-world clinical settings and capable of meeting urgent unmet needs.
The HAM-Ven combination’s mechanism deserves closer scrutiny: venetoclax’s selective inhibition of BCL2 disrupts the delicate balance of pro-survival and pro-apoptotic signals in AML blasts, rendering these cells more susceptible to apoptosis when exposed to the DNA-damaging effects of cytarabine and the anthracenedione mitoxantrone. By integrating these agents, the regimen attacks AML on multiple biological fronts, counteracting the disease’s notorious proliferative resilience and chemoresistance.
The success of the RELAX study further enriches Dresden’s legacy as a global center of excellence in hematology and leukemia research. Building upon their previous achievements with novel therapies for acute promyelocytic leukemia (APL), this latest accomplishment exemplifies how robust academic inquiry, clinical expertise, and collaborative frameworks can innovate treatment paradigms for complex hematological cancers.
Prof. Esther Troost, Dean of the Faculty of Medicine at TUD, reflects on the study’s broader contribution to medical science. She notes that conducting meticulous academic trials is indispensable for establishing the safety and efficacy of emergent therapeutic protocols. It is only through such rigorous processes that the oncology community can confidently adopt new treatment standards, ensuring patient-centered care informed by robust evidence.
Prof. Uwe Platzbecker, Medical Director of Dresden University Hospital, highlighted the transformative potential of the HAM-Ven regimen as a substantial leap forward in preparing AML patients for life-saving interventions. The capacity to substantially increase remission rates in a patient population traditionally plagued by poor responses effectively means reshaping the prognostic landscape and offering renewed hope for survival.
The RELAX trial was orchestrated under the auspices of the TU Dresden Faculty of Medicine and Dresden’s Coordination Center for Clinical Studies, with coordination by the Clinical Studies Department of Medical Clinic and Polyclinic I within Dresden University Medicine. Conducted through the Study Alliance Leukemia (SAL)—one of Germany’s foremost AML study consortia—the trial spanned more than 50 specialized centers across Germany and Austria. This expansive network facilitated robust multicenter data collection, ensuring that study findings reflect diverse clinical practice environments and patient demographics.
Looking ahead, the research team is committed to further exploring HAM-Ven’s applicability, including detailed molecular characterizations to identify predictive biomarkers and optimize patient selection. Moreover, integrating this regimen with other emerging targeted therapies and immunomodulatory strategies remains an active area of investigation, potentially multiplying therapeutic gains.
In conclusion, the RELAX study’s pioneering insights signal a pivotal advance in relapsed and refractory AML management, achieving significantly improved remission rates with the HAM-Ven combination, thereby enhancing candidacy for curative stem cell transplantation. This breakthrough not only redefines salvage therapy benchmarks but also reaffirms the vital role of innovative academic-industry collaborations in accelerating oncology breakthroughs, ultimately improving patients’ odds of recovery against this devastating disease.
Subject of Research: Treatment of relapsed or refractory acute myeloid leukemia using combined chemotherapy and targeted BCL2 inhibition
Article Title: Venetoclax plus high-dose cytarabine and mitoxantrone as salvage treatment for relapsed or refractory acute myeloid leukaemia (RELAX): a multicentre, single-arm, phase 1/2 trial
News Publication Date: 4 March 2026
Web References: http://dx.doi.org/10.1016/S2352-3026(25)00358-8
Keywords: Acute myeloid leukemia, AML, relapsed leukemia, refractory leukemia, BCL2 inhibitor, venetoclax, cytarabine, mitoxantrone, chemotherapy, stem cell transplant, hematologic malignancy, targeted therapy, salvage therapy
