The U.S. Food and Drug Administration (FDA) has granted Fast Track designation for STRO-002. The investigational drug, being developed by Sutro Biopharma, is a folate receptor alpha (FolRα)-targeting antibody-drug conjugate (ADC) for the treatment of patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer who have received one to three prior lines of systemic therapy.

Antibody-drug Conjugates or ADCs, including Sutro’s investigational STRO-002, are highly targeted biopharmaceutical drugs that combine monoclonal antibodies specific to surface antigens present on particular tumor cells with highly potent anti-cancer agents linked via a chemical linker. With ten approved drugs on the market, ADCs have become a powerful class of therapeutic agents in oncology and hematology.

Unmet medical need
Although real progress has been made, women diagnosed with platinum-resistant or refractory relapsed epithelial ovarian cancer generally have a poor prognosis, and in patients with advanced disease, this may ultimately result in fatality. Today, effective treatment of platinum resistance remains the largest unmet medical need in ovarian cancer.

Fast Track designation
The FDA’s Fast Track designation is intended to facilitate the development and review of drug candidates that treat serious conditions or life-threatening conditions and demonstrate the potential to address an unmet medical need. A drug candidate that receives Fast Track designation can expect more frequent interaction with the FDA to discuss the drug candidate’s development plan, the potential for accelerated approval, and the possibility of priority review, if relevant criteria are met at the time of submission of a Biologic Licensing Application (BLA).

Clinical development
STRO-002-GM1, is a Phase 1 trial for STRO-002 for patients with advanced ovarian cancer that have progressed or relapsed after standard of care treatments, to assess efficacy, safety, and tolerability. The dose-escalation cohort has been completed and the dose-expansion cohort has enrolled patients from sites in the U.S. and in Spain, with enrollment ongoing. Patients are not pre-selected for FolRα expression but are required to provide a tissue sample for FolRα analysis prior to study treatment. Patients are randomized 1:1 and treated with STRO-002 at either 4.3 or 5.2 mg/kg every three weeks.

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Earlier this year data from Sutro Biopharma’s dose-escalation cohort of the Phase 1 study of STRO-002, a folate receptor alpha (FolRα) targeting antibody-drug conjugate (ADC) for patients with advanced, progressive ovarian cancer were presented as a poster at the American Society of Clinical Oncology (ASCO) 2021 Annual Meeting to be held on June 4-8, 2021 [1]

Encouraging activity
“We are pleased with the FDA’s decision to grant Fast Track designation for STRO-002 and welcome the opportunity to have more frequent interactions with the agency,” noted Arturo Molina, MD, MS, Chief Medical Officer of Sutro Biopharma.

“We continue to be enthused by the potential of the STRO-002 program, which has shown encouraging preliminary activity and tolerability in our Phase 1 dose-escalation study in ovarian cancer, and plans to continue to work with the FDA to potentially accelerate our clinical and regulatory efforts.”

Important recognition
“Receiving Fast Track designation is an important recognition for STRO-002 as a potentially best-in-class FolRα ADC for women with ovarian cancer. We look forward to further collaboration with the FDA to bring this potentially important therapeutic option to women in advanced stages of their disease with limited treatment options,” add Bill Newell, Chief Executive Officer of Sutro Biopharma.

Sutro’s proprietary and integrated cell-free protein synthesis platform XpressCF® and site-specific conjugation platform XpressCF+™ led to the discovery of STRO-002, Sutro’s first internally-developed ADCs.

Clinical trials
Study of STRO-002, an Anti-Folate Receptor Alpha (FolRα) Antibody Drug Conjugate in Ovarian & Endometrial Cancers – NCT03748186

Reference
[1] Naumann RW, Braiteh FS, Martin LP, Hamilton EP, Diaz JP, Diab S, Schilder RJ, Moroney JW, et al. Phase 1 dose-escalation study of STRO-002, an antifolate receptor alpha (FRα) antibody-drug conjugate (ADC), in patients with advanced, progressive platinum-resistant/refractory epithelial ovarian cancer (EOC). Abstract: 5550; Presented at: American Society of Clinical Oncology (ASCO), held June 4 – 8, 2021.J Clin Oncol 39, 2021 (suppl 15; abstr 5550).

An edited version of this article was first published in ADC Review | Journal of Antibody-drug Conjugates.

Featured Image: Women suffering from ovarian cancer. Photo courtesy: © 2016 – 2020 Fotolia/Adobe. Used with permission.

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