SEATTLE, WA – Aptevo Therapeutics Inc. (Nasdaq:APVO), a clinical-stage biotechnology company developing novel immune-oncology therapeutics based on its proprietary ADAPTIR™ and ADAPTIR-FLEX™ platform technologies, today announced new interim data for mipletamig in combination with venetoclax and azacitidine in newly diagnosed acute myeloid leukemia (AML) patients who are either elderly or unfit for intensive chemotherapy. In data from two trials, the combination has demonstrated robust clinical activity, delivering an 86% clinical benefit rate (CR/CRi/PR*)with zero patients experiencing the common symptom of cytokine release syndrome (CRS). These data support an emerging efficacy profile coupled with differentiated patient safety and tolerability that is additive to the current AML standard-of-care therapy.
“The emerging mipletamig data in frontline AML are highly encouraging and highlight the differentiated profile we believe is needed to advance treatment in frontline AML,” said Dirk Huebner, M.D., Chief Medical Officer of Aptevo Therapeutics. “In this study we are observing strong remission rates in a growing number of evaluable patients together with a consistently favorable safety and tolerability profile, including the absence of cytokine release syndrome. Achieving meaningful clinical activity while maintaining this level of safety and tolerability is essential in the frontline AML setting, where therapies must be compatible with established regimens. These results reinforce our belief that mipletamig can be successfully combined with venetoclax and azacitidine, with the potential to enhance outcomes for older and/or unfit AML patients who continue to face poor prognosis and limited treatment options.”
Huebner continued, “Importantly, four of the patients treated to date have proceeded to allogeneic stem cell transplant, which represents the best possible outcome in AML treatment and is rarely achieved in the older or unfit frontline patient population.”
Data Highlights Include:
Among the evaluable frontline patient population treated to date (N=28), including 24 patients from the RAINIER trial and 4 patients from the completed dose expansion trial, mipletamig in combination with venetoclax and azacitidine has demonstrated:
- 100% of frontline patients have remained free of cytokine release syndrome (CRS)
- 86% clinical benefit rate
- 79% achieved CR or CRi
- 61% achieved CR
- 55% of patients who achieved CR/CRi had blast reductions that reached the important measurable residual disease-negative level, a result that is typically associated with stronger, more durable responses
- 35% of patients with remissions had the TP53 genetic mutation, a high-risk biomarker typically associated with poor prognosis in AML and for which most treatment options frequently fail
Collectively, these data demonstrate mipletamig’s potential to meaningfully enhance frontline AML treatment in older and/or unfit patients, by improving efficacy outcomes without materially increasing toxicity.
“Our frontline data show that mipletamig has the potential to play a meaningful role in the future frontline AML treatment,” said Marvin White, President and Chief Executive Officer of Aptevo Therapeutics. “From the outset, our objective has been to develop an AML drug capable of integrating into the current standard-of-care and improving outcomes for patients who continue to face poor prognoses. The data reported reinforces our conviction that mipletamig may represent a differentiated approach with the potential to complement existing frontline therapies in a practical and impactful way. As enrollment continues, we remain focused on advancing our RAINIER trial and generating the data needed to support mipletamig’s long-term role in AML treatment.”
*(Clinical Benefit Rate: CR = complete remission; CRi = complete remission with incomplete blood marker recovery; PR = partial remission.)
Consistent Safety and Tolerability Profile Maintained Across Patients Treated to Date
In frontline patients treated to date, no cytokine release syndrome (CRS) has been observed. Together with strong efficacy outcomes, this outcome underscores mipletamig’s safety and combinability, potentially offering a superior treatment in the future. This safety profile is particularly important in frontline AML, where tolerability and combinability are essential for treating older patients and/or those with comorbidities.
About the RAINIER Trial
RAINIER, a frontline AML study, is a Phase 1b/2 dose optimization, multi-center, multi-cohort, open label study. Subjects are adults aged 18 or older, newly diagnosed with AML who are not eligible for intensive induction chemotherapy. RAINIER will be conducted in two parts. First, a Phase 1b dose optimization study in frontline AML patients followed by a Phase 2 study. The Phase 1b trial consists of 28-day cycles of treatment across multiple, sequential cohorts.
About Mipletamig
Aptevo’s wholly owned lead proprietary drug candidate, mipletamig, being evaluated for the treatment of AML, is differentiated by design™ to redirect the immune system of the patient to destroy leukemic cells and leukemic stem cells expressing the target antigen CD123, which is a compelling target for AML due to its overexpression on leukemic stem cells and AML blasts. This antibody-like recombinant protein therapeutic is designed to engage both leukemic cells and T cells of the immune system and bring them closely together to trigger the destruction of leukemic cells. Mipletamig is purposefully designed to reduce the likelihood and severity of CRS by use of the CRIS-7-derived CD3 binding pathway, an approach that differentiates Aptevo from competitors. Mipletamig has received orphan drug designation (“orphan status”) for AML according to the Orphan Drug Act. Orphan drug designation provides key advantages-including the opportunity to seek U.S. market exclusivity for a specific period of time upon approval, FDA fee reductions, and access to development and tax credits. Mipletamig has been evaluated in more than 120 patients over three trials to date.
About Aptevo Therapeutics
Aptevo Therapeutics Inc. (Nasdaq:APVO) is a clinical-stage biotechnology company focused on developing novel bispecific and trispecific immunotherapies for the treatment of cancer. The Company has two clinical candidates and six preclinical candidates with different mechanisms of action designed to target a range of solid tumors. All pipeline candidates were created from two proprietary platforms, ADAPTIRand ADAPTIR-FLEX. The Aptevo mission is to improve treatment outcomes and transform the lives of cancer patients. For more information, please visit www.aptevotherapeutics.com.
Contact
Miriam Weber Miller
Vice President, Investor Relations & Corporate Communications
Aptevo Therapeutics
Email: [email protected] or [email protected]
Phone: 206-859-6628