On September 9, 2020 Sutro Biopharma, Inc. (NASDAQ: STRO), a clinical-stage drug discovery, development and manufacturing company focused on the application of precise protein engineering and rational design to create next-generation oncology therapeutics, reported further STRO-002 updated interim Phase 1 safety and preliminary efficacy data in ovarian cancer, and an upcoming presentation at the 2020 xDigital Annual Global Meeting of the International Gynecologic Cancer Society (IGCS) on Sept. 10, 2020 (Press release, Sutro Biopharma, SEP 9, 2020, View Source [SID1234564912]).

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The interim clinical data from this dose escalation study evaluating the anti-folate receptor alpha (FolRα) antibody drug-conjugate (ADC) STRO-002 included 34 patients treated at 2.9 mg/kg and higher dose levels, with an overall response rate of 24% in 33 evaluable patients with post-baseline scans, with durability of 44% of patients on treatment for 16 weeks or greater and 12% of patients on treatment for 1 year or greater. The results announced today are based on a data cut-off date of Aug. 31, 2020, with 39 patients having been enrolled in the dose escalation study.

"We are pleased to observe improved efficacy outcomes as our data mature with longer follow-up, and the observed rate of objective response, stable disease and overall disease control during this study suggest that STRO-002 is potentially superior to other targeted ADC therapies being studied currently in ovarian cancer," said Dr. Arturo Molina, Chief Medical Officer of Sutro Biopharma. "Taken together with the optimized design approach to ADC safety, we believe that STRO-002 will be a potent and well-tolerated treatment option for patients. Next up, we plan to initiate a dose expansion trial in patients with less heavily pretreated ovarian cancer in the fourth quarter of 2020."

The interim clinical data for STRO-002 in patients evaluable for RECIST response include eight patients with partial responses. Seven patients with partial responses and 13 patients with stable disease achieved a disease control rate of 60% at 12 weeks or greater. STRO-002 continued to be well-tolerated and 87% of all treatment-emergent adverse events (AEs) were Grade 1 or 2; prophylactic corticosteroid eye drops have not been required. The most common Grade 3 and 4 AE was reversible neutropenia, with neuropathy and arthralgia observed at higher doses.

"We continue to see an encouraging efficacy and safety profile for STRO-002 in this heavily pretreated patient population," said Wendel Naumann, M.D., gynecologic oncologist at Levine Cancer Institute and a principal investigator on the STRO-002 study. "While Sutro plans to explore further dose optimization during dose expansion in a less heavily pre-treated patient population, we anticipate that the optimized therapeutic window and the recommended Phase 2 dose will be in the 4.3 to 5.2 mg/kg range. There is a tremendous unmet need for effective treatments in patients with advanced platinum-resistant and refractory epithelial ovarian cancer and we look forward continuing this study to explore the use of STRO-002 in treating this disease."

The Phase 1, open-label, multicenter, dose escalation trial with dose expansion of STRO-002 has completed enrollment and ongoing follow-up and will continue to evaluate the safety, tolerability, and preliminary anti-tumor activity of STRO-002 in adults with advanced epithelial ovarian cancer, including fallopian or primary peritoneal cancer, and endometrial cancer. The trial is registered with clinicaltrials.gov identifier NCT03748186. Sutro discovered, developed and manufactures STRO-002 using its proprietary XpressCF cell-free protein synthesis and XpressCF+ site-specific conjugation technologies.

Conference Call Information:
To access the conference call and live audio webcast on Wednesday, Sept. 9, at 5:30 p.m. EDT, please dial (877) 407-8974 (domestic) or (201) 389-0894 (international).

The conference call will be webcast via the Investors page on the Company’s website at ir.sutrobio.com. Approximately two hours following the live event, a webcast replay of the conference call will be available through the Company Presentation page of the Investor section of the company’s website at www.sutrobio.com for approximately 30 days.

Presentation Details:

Title:

Phase 1 Dose-Escalation Study of STRO-002, an anti-Folate Receptor alpha (FRα) Antibody Drug Conjugate (ADC), in Patients with Advanced Platinum-Resistant/Refractory Epithelial Ovarian Cancer (OC)

Abstract Number:

138 IGCS20_1113

Date/Time:

Sept. 10-13, 2020

Presenter:

Wendel Naumann, M.D.

The e-poster presentation can be found on the IGCS Meeting website and is also accessible through the Clinical/Scientific Presentation and Publication Highlights page of the News section of Sutro Biopharma’s website at www.sutrobio.com on the day of the poster presentation.