AML Drug Hits Pre-Specified Primary Endpoint in Phase 2

Data from a Phase 2 trial of galinpepimut-S (GPS) in acute myeloid leukemia (AML) have been published in the current issue of the peer-reviewed medical journal Blood Advances.

GPS, SELLAS Life Sciences’ lead candidate, is licensed from Memorial Sloan Kettering Cancer Center and targets the Wilms Tumor 1 (WT1) protein, which exists in several different tumor types and has been identified by the National Cancer Institute (NCI) as the leading target for cancer immunotherapy.

AML initially presents in the bone marrow and promptly spreads to the blood. It is characterized by the rapid expansion of white blood cells, and the enlarged cells obstruct the production of typical blood cells.

SELLAS believes that the drug has potential as a monotherapy or in combination to address a wide variety of hematologic malignancies and solid tumor indications, including AML.

The open-label Phase 2 study enrolled 22 adult patients with AML and evaluated GPS administered in 6 vaccinations over 10 weeks. All enrolled patients had the potential to receive 6 additional monthly doses if they remained in complete remission (CR1). GPS met its pre-specified primary endpoint of ≥34% actual overall survival (OS) rate at three years with a GPS-induced OS rate of 47.4%.

Additionally, median disease-free survival (DFS) from first complete response was 16.9 months. The OS from diagnosis has not yet been reached, but is expected to be less than 67.6 months.

President & Chief Executive Officer of SELLAS confirms that the data are consistent with prior positive results in AML and support the continued development of GPS.

“We are encouraged by the collective supporting evidence generated by our Phase 1 and Phase 2 AML studies,” said Dr Stergiou in a press release. “We wholeheartedly appreciate the participation of patients and their families in all our clinical studies, as well as the exceptional physicians and study teams. We look forward to advancing GPS into a Phase 3 trial in AML.”

Median OS post-diagnosis was 35.8 months for patients in the older cohort (age >60; n=13).

“We were especially pleased with the findings in AML patients over sixty years of age, which are important considering the poor prognosis particularly for those patients, even with optimal use of current care standards” stated Peter Maslak, M.D., Chief, Immunology Laboratory Service at Memorial Sloan Kettering Cancer Center and Principal Investigator of the study.

GPS was well tolerated throughout the study, with the most frequent side effects being Grade 1/2 injection site reactions (46%), fatigue (32%), and skin induration (32%). Fourteen patients (64%) completed more than 6 vaccinations, and 9 (41%) received all 12 vaccine doses.

Pending funding availability, phase 3 clinical trials are planned for GPS in two indications; AML and malignant pleural mesothelioma (MPM). It is also currently in development for multiple myeloma and ovarian cancer.

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