FDA Fast-tracks Magrolimab for Treatment of Myelodysplastic Syndrome, Acute Myeloid Leukemia

Magrolimab, an experimental antibody developed by Forty Seven, was granted fast track designation by the U.S. Food and Drug Administration (FDA) for the treatment of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS).

The designation is given to therapies that show potential to treat serious health conditions, and is intended to accelerate their development and approval by providing more frequent meetings and discussions with the FDA. Fast track therapies may also be considered for accelerated approval.

“We are pleased to receive Fast Track Designation for magrolimab in both MDS and AML, emphasizing the unmet need among these patients, and further equipping us to execute on our goal of delivering magrolimab as a promising new option to treating physicians,” Mark Chao, MD, PhD, founder and vice-president of clinical development at Forty Seven, said in a news release.

Magrolimab, formerly known as 5F9, is a monoclonal antibody against CD47, a protein that works as a “don’t eat me” signal used by cancer cells to avoid being ingested by macrophages — a kind of immune cell that engulfs invaders.

The investigative therapy works much like checkpoint inhibitors. But instead of activating T-cells, it improves the ability of macrophages to identify and eliminate cancer cells.

Because this evading mechanism is used by several cancer types, magrolimab represents a promising approach for a wide range of solid and blood cancers. The treatment has already received fast track status for two other blood cancers, diffuse large B-cell lymphoma and follicular lymphoma.

A Phase 1b clinical trial (NCT03248479) is assessing the safety, tolerability, and efficacy of magrolimab in AML and MDS patients. The trial is currently recruiting both previously-treated patients, who will receive magrolimab alone, and patients who have not received any prior therapy, in which case they will be offered magrolimab in combination with Celgene‘s Vidaza (azacitidine).

Magrolizumab will be administered up to two times a week, while Vidaza is to be taken every day for seven days, in each four-week cycle.

Initial results, presented at the 24th European Hematology Association Congress in June, showed that magrolimab was well-tolerated alone and also in combination with Vidaza. Among patients who had received prior lines of therapies, the response rate was 10%.

However, the most encouraging results were seen in untreated patients, with 64% of AML and 100% of MDS patients responding to the combination treatment, which compares favourably to Vidaza alone, the company said.

However, these patients responded faster to the combination therapy (within a median of 1.9 months) than to Vidaza alone.

The trial is now enrolling patients into expansion cohorts of AML and MDS patients to continue studying the treatment’s safety and efficacy.

“We were encouraged by the initial data from our Phase 1b clinical trial, which showed a 100% overall response rate (ORR) in untreated higher-risk MDS patients and a 64% ORR in untreated AML patients, along with a rapid time to response,” said Chao.

“We look forward to continuing our productive dialogue with the FDA as we advance magrolimab through the clinic and finalize the design of our pivotal program in MDS,” he added.