Aptevo Therapeutics achieves major breakthrough with mipletamig in acute myeloid leukemia

Aptevo Therapeutics has unveiled remarkable findings from Cohort 1 of its RAINIER clinical trial for mipletamig, a bispecific antibody aimed at tackling acute myeloid leukemia (AML). The results revealed a 100% complete remission rate, achieved within 30 days of initiating treatment. Notably, two out of three patients achieved minimal residual disease (MRD)-negative status, meaning even the most sensitive tests detected no remaining cancer cells.

These outcomes reinforce mipletamig’s potential as a game-changer in acute myeloid leukemia treatment. The findings echo earlier data from a dose-expansion trial, which also demonstrated a 100% remission rate among frontline AML patients. Marvin White, CEO of Aptevo Therapeutics, emphasized that these consistent results demonstrate mipletamig’s ability to elevate the standard of care for AML patients.

Cohort 1 Results Set Stage For Next Phase

The impressive Cohort 1 results mark a pivotal moment for Aptevo’s clinical program. Building on this success, the company is advancing to Cohort 2 enrollment as part of the RAINIER trial. This multi-centre study will involve up to 39 participants and focus on optimizing dosage levels. Patients in Cohort 2 will receive mipletamig in combination with venetoclax and azacitidine, currently standard therapies for AML.

This trial represents a critical step in Aptevo’s mission to provide safer, more effective treatments for acute myeloid leukemia. According to the company, mipletamig’s unique design not only delivers high remission rates but also minimizes the risks associated with similar therapies.

Unique Mechanism Enhances Safety And Efficacy

Mipletamig’s innovative mechanism of action differentiates it from other AML treatments. By targeting CD3 and CD123 antigens, mipletamig brings immune cells into close proximity with leukemic cells, effectively triggering their destruction. This mechanism also reduces the likelihood of cytokine release syndrome (CRS), a dangerous side effect seen in many immunotherapies.

Dirk Huebner, Chief Medical Officer at Aptevo Therapeutics, highlighted the importance of these outcomes, particularly for high-risk patients. In this trial, one patient with a TP53 mutation—often resistant to traditional treatments—achieved MRD-negative status, showcasing mipletamig’s efficacy in overcoming significant challenges in acute myeloid leukemia care.

Promising Future For Aptevo’s AML Program

The success of the RAINIER trial builds momentum for Aptevo Therapeutics, which has prioritized the development of bispecific immunotherapies. Mipletamig, which has already received orphan drug designation under the Orphan Drug Act, is poised to become a cornerstone in the fight against acute myeloid leukemia.

Aptevo’s broader pipeline includes other innovative therapies, such as ALG.APV-527 for solid tumors. However, mipletamig remains its flagship product, with nearly 90 patients treated across multiple trials to date. The company continues to focus on advancing its programs to deliver transformative results for patients with high unmet medical needs.

Expert Insights On Cohort 1 Results

Experts are optimistic about the implications of the Cohort 1 results. Achieving a 100% complete remission rate, especially with MRD-negative outcomes, is a significant milestone in AML research. These findings suggest mipletamig has the potential to deliver deep and durable responses, even for patients with poor prognoses.

Huebner noted that achieving MRD-negative status is strongly correlated with longer remissions and better survival rates. This breakthrough offers hope to many AML patients who have historically faced limited options, particularly those ineligible for intensive chemotherapy.

Reinforcing Mipletamig’s Potential

Mipletamig’s performance in acute myeloid leukemia treatment underscores its promise as a first-line therapy when combined with venetoclax and azacitidine. With the positive Cohort 1 results, Aptevo Therapeutics is well-positioned to redefine AML care standards. The company’s commitment to innovation, coupled with a focus on patient safety and efficacy, makes mipletamig a key player in the evolving oncology landscape.