Sutro Biopharma Inc. (NASDAQ:STRO) Reports Positive Preliminary STRO-002 Dose Escalation Trial Results in Ovarian Cancer Patients

Sutro Biopharma Inc. (NASDAQ:STRO) has released a clinical update from its ongoing dose-escalation phase 1 STRO-002 study for ovarian cancer patients. STRO-002 is the company’s antibody-drug conjugate targeting folate receptor alpha.

Sutro finalized enrolment in the STRO-002 study in August

STRO-002-GM1 study is a monotherapy single-arm dose-escalation study for ovarian cancer patients not picked based on folate receptor alpha-expression levels. In August 2020, the dose-escalation part of the trial fully enrolled 39 patients. The enrolled patients were pre-treated with an average of 6 previous therapy lines, which include the standard of care platinum-based regimens, PARP inhibitors, checkpoint inhibitors, and bevacizumab.

The dose-escalation trial also included 34 treated patients with clinically active dose levels of more than 2.9mg/kg. Interestingly 31 patients had post-baseline scans evaluable for RECIST responses. According to October 30, 2020, data cut off the average treatment time was 19 weeks with ten patients remaining on treatment. Out of the total enrolled patients, 10 met RECIST response criteria, with one patient attaining complete response while 9 achieved a complete partial response. There was disease control in 23 patients at 12 weeks, with 18 patients attaining disease control at 16 weeks. Four patients remained on treatment for 52 weeks, and only three patients were on treatment after 64 weeks.

STRO-002 shows potential as an ovarian cancer treatment

Most importantly, STRO-002 continued to demonstrate favorable tolerability, and around 86% of the treatment-emergent adverse events were Grade 1 and 2. Notably, there were no ocular toxicity signals observed, and prophylactic corticosteroid eye drops were not necessary. The most notable grade 3 and 4 adverse events were reversible neutropenia. Also, Grade 3 neuropathy and arthralgia were reported, but standard medical treatment managed the event, including dose delays or reductions without proof of compromised efficacy.

Dr. Lainie Martin, an investigator of the STRO-002 study, said that there has been encouraging clinical benefit demonstrated by STRO-002 in patients having advanced platinum and refractory ovarian cancer. Martin said that the deepening patient response and diseases control with time shows that STR-002 can be a possible treatment alternative for ovarian cancer patients.