Investigational Immunotherapy SRF231 Granted FDA Orphan Drug Status for Multiple Myeloma

The U.S. Food and Drug Administration has granted orphan drug status to SRF231 to treat multiple myeloma, according to Surface Oncology, which is developing the investigational therapy.

Orphan drug designation aims to assist in developing therapies for rare and serious diseases that have a high unmet need by providing benefits such as seven years of market exclusivity after approval and exemption from FDA application fees.

SRF231 is being tested in an open-label Phase 1 trial (NCT03512340) currently enrolling for a total of 148 participants.

“While the potential applications for SRF231 in oncology are quite broad, we are particularly excited about the opportunity to provide benefit to patients with multiple myeloma. We have already demonstrated the ability of our antibody to increase phagocytosis of myeloma cells and to shrink tumors in preclinical models,” Rob Ross, MD, chief medical officer of Surface Oncology, said in a press release. “Receiving orphan designation for SRF231 represents an important milestone as we continue to progress the program in the clinic in multiple myeloma and other cancer types.”

SRF231 is a human antibody that targets and inhibits the activity of a protein called CD47 that is highly expressed in cancer cells. CD47 works as a “don’t eat me” signal that prevents cancer cells from being recognized by the “professional eaters” of the immune system called macrophages. By blocking CD47 signaling, SRF231 allows macrophages to recognize and eliminate these cancer cells.

The Phase 1 trial, taking place at sites in the U.S. and Canada, is assessing SRF231 in patients with solid tumors and blood cancers, including multiple myeloma.

In the first part of the two-part trial, researchers will test ascending doses of SRF231, given in 21-day treatment cycles for up to two years, to establish the best recommended dose for further study.

In the second part, the primary objectives are to determine the safety and tolerability of SRF231 in five tumor types. Additional goals include measures of effectiveness, including overall response rates, duration of response, and progression-free survival.

In a previous preclinical study, researchers tested SRF231 in models of multiple myeloma and lymphoma. Treatment, alone or in combination with other therapies, led to robust tumor cell clearance in both cancer models.

Results were published in the journal Blood in a study titled “CD47 Monoclonal Antibody SRF231 Is a Potent Inducer of Macrophage-Mediated Tumor Cell Phagocytosis and Reduces Tumor Burden in Murine Models of Hematologic Malignancies.”