Sutro expects the results to support its investigational new drug application for STRO-001. The U.S. Federal Drug Administration must approve the application before the company can start clinical trials of the therapy. It is planning a Phase 1 trial in early 2018.
STRO-001, an antibody drug conjugate, targets the surface protein CD74. It is found in up to 90 percent of malignant B-cells, but almost no normal tissue. After binding to a cell with CD74, the drug releases a toxic payload that kills the cell.
The company presented the findings at the American Association for Cancer Research annual meeting in Washington in April. STRO-001 eliminated malignant plasma B-cells in mice with multiple myeloma mice, researchers said. And the mice remained tumor-free through the four-month study, while placebo-treated mice died within 35 days.
Sutro is now reporting that STRO-oo1 eliminates tumor cells or significantly delays tumor growth in mice with large B-cell lymphoma and mantle cell lymphoma.
In addition, the therapy led to mice with mantle cell lymphoma living longer than mice treated with a placebo, whose disease continued to progress.
Combining STRO-001 with the chemotherapies Levact (bendamustine) and Rituxan (rituximab) was more effective against diffuse large B-cell lymphoma tumors than chemo alone, the team added.
They reported the results in June at the 14th International Conference on Malignant Lymphoma in Lugano, Switzerland, and at the 22nd Congress of the European Hematology Association in Madrid. The presentation was titled “STRO-001, a Novel Anti-CD74 Antibody Drug Conjugate (ADC) for Treatment of B-Cell Non-Hodgkin’s Lymphomas (NHL).”
STRO-001 also reduced multiple myeloma activity, or even eradicated the cancer, in mice, Sutro said.
In another presentation at the hematology convention, it reported that 129 days after receiving STRO-001, none of the mice in a myeloma study had cancer in their bone marrow. In contrast, control animals died within 35 days, with half their bone marrow filled with myeloma cells.
The presentation was titled “Targeting CD74 in Multiple Myeloma with a Novel Antibody Drug Conjugate (ADC), STRO-001.”
“These results are the clearest, most compelling evidence that STRO-001 performs effectively in multiple malignant B-cell lines” and animal tumor models, Bill Newell, CEO of Sutro, said in a press release.