A Phase 3 Study of Pasritamig Plus Docetaxel

Pasritamig is a bispecific T-cell engager that targets human kallikrein 2 (KLK2), a protein found primarily in prostate tissue and often retained in advanced prostate cancer. This drug brings T cells into close contact with KLK2-expressing tumor cells, directing immune responses against the cancer. In phase 1 studies, pasritamig was evaluated in men with metastatic castration-resistant prostate cancer that had progressed despite multiple prior treatments. At the recommended dose, over 40% of participants had a reduction in PSA of at least 50%. Some individuals experienced sustained disease control. Most adverse effects were mild, with low rates of fever-related reactions, no serious neurotoxicity, and very few participants needing to stop or adjust treatment due to side effects. The phase 1 dosing schedule allows treatment every six weeks, in a setting that does not require hospitalization.​

Building on these early results, the ongoing phase 3 KLK2-PASenger trial is testing pasritamig in combination with docetaxel, a widely used chemotherapy for metastatic prostate cancer. Recent research suggests that docetaxel may alter the tumor immune environment, increasing T-cell activity within the tumor and making the cancer more susceptible to immune therapy. The combination uses the anticancer effects of chemotherapy alongside immune engagement to attack cancer on multiple fronts. Preclinical evidence supports the rationale for this approach, indicating that chemotherapy and T-cell engagers can work together by making more tumor cells visible and vulnerable to immune attack.​

The trial is notable for its use of an intermittent dosing strategy with pasritamig, as evidence indicates that spacing out infusions can preserve the effectiveness of T cells and limit immune exhaustion. This approach is designed to maintain a pool of functional T cells that can respond to cancer over time.​

Clinical trial.