New Immunotherapy Shows 62% Response Rate in Platinum-Resistant Ovarian Cancer

Two experimental immunotherapy drugs have shown remarkable promise in treating advanced gynecologic cancers, offering new hope for patients with limited treatment options. These findings were presented at the Society of Gynecologic Oncology meeting and represent significant advances in cancer treatment.

Mocertatug rezetecan, an antibody-drug conjugate targeting the B7-H4 protein, demonstrated impressive response rates in clinical trials. Among 103 patients with platinum-resistant ovarian cancer, objective response rates ranged from 31-62% depending on dose levels. In endometrial cancer patients, response rates reached 67% at higher doses. The drug targets B7-H4, a protein expressed in 95% of gynecologic cancers.

The second drug, SYS6043, targets B7-H3 protein and achieved disease control in 80-90% of patients with advanced ovarian, endometrial, or cervical cancers. In ovarian cancer specifically, 45.7% of patients achieved partial responses, with median progression-free survival of 8.3 months. Responses occurred regardless of B7-H3 expression levels.

Both treatments showed manageable safety profiles. Common side effects included gastrointestinal symptoms, neutropenia, and anemia. Grade 3 or higher treatment-related adverse events occurred in 28-38% of patients, with most being manageable. Few patients discontinued treatment due to side effects.

These results are particularly significant because they target cancers that have become resistant to standard platinum-based chemotherapy. Based on these promising results, global phase III trials are planned for mocertatug rezetecan, potentially bringing these treatments closer to clinical availability for patients with advanced gynecologic cancers.