“There is a growing need for new treatment options for patients with multiple myeloma,” Bill Newell, Sutro’s CEO, said in a news release. “This orphan drug designation is a great step toward advancing our uniquely designed STRO-001 that could bring new treatment options to patients in need.”
STRO-001 is an antibody drug conjugate (ADC) that targets the CD74 protein, commonly found in myeloma cells but almost nonexistent in healthy tissue. Once STRO-001 binds to CD74, the agent releases a toxic compound into cancer cells, causing them to die.
In a preclinical study, researchers found that CD74 was present in 97% of the multiple myeloma bone marrow samples examined. In addition, STRO-001 had a cytotoxic effect in patient-derived multiple myeloma cell lines, plus reduced tumor burden and prolonged survival in cellular models.
Sutro’s investigational therapy was developed using the company’s proprietary XpressCF+ technology, which does not require living cells to produce their protein products. This allows researchers to produce proteins faster and in a greater amount than conventional methods using intact, functioning cells.
“STRO-001 was designed to directly target cancer cells to deliver a cytotoxic payload. Building upon our XpressCF+ platform we plan to develop better options to treat tumors with greater precision,” Newell said.
STRO-001 is already being studied in a Phase 1, open-label, multicenter, dose-escalation trial (NCT03424603) in adult subjects with B-cell malignancies, including multiple myeloma and non-Hodgkin’s lymphoma, who are intolerant or in whom all other available therapies have failed. The study is currently recruiting patients at seven U.S. sites.
Investigators plan to recruit 220 patients; the study consists of two parts.
In part 1, patients will receive ascending doses of the medicine to determine its safety, the maximum tolerated dose, and the recommended dose for Phase 2 testing. This part of the study is expected to last 18 months.
In part 2, which will take two years to complete, subjects will be dosed with the recommended Phase 2 dose to evaluate preliminary signs of anti-tumor activity in both diseases and continue testing the treatment’s safety.
In both parts, STRO-001 will be administered as an intravenous infusion every two weeks until disease progression. Patients will have their blood drawn every week for cycles 1-3, each lasting four weeks, and every two weeks starting with cycle 4.