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New oral therapy shows early signs of safety and effectiveness in patients with advanced, treatment-resistant prostate cancer

MD Anderson Research News October 24, 2025

• Trial shows promising early results for HLD-0915, a first-in-class regulated induced proximity targeting chimera (RIPTAC) treatment
• Metastatic castration-resistant prostate cancer (mCRPC) is a hard-to-treat prostate cancer that no longer responds to standard hormone therapy
• Preliminary data suggest HLD-0915 has a favorable safety profile with evidence of tumor shrinkage and PSA decline in mCRPC patients
• HLD-0915 received FDA fast track designation recognizing its potential to treat advanced prostate cancer

BOSTON, OCTOBER 24, 2025 ¨D A first-in-human clinical trial led by researchers at Â鶹ӳ»­ MD Anderson Cancer Center showed that the novel oral treatment HLD-0915 was well tolerated with preliminary evidence of tumor shrinkage and lower PSA levels in patients with metastatic castration-resistant prostate cancer (mCRPC).

Data from the study were presented today by , assistant professor of Genitourinary Medical Oncology, at the .

What is HLD-0915 and what have early clinical trial results shown? 

HLD-0915 is a first-in-class regulated induced proximity targeting chimera (RIPTAC) treatment designed to simultaneously target both androgen receptors (ARs) and protein BRD4 in a ternary complex, and to inhibit the activity of BRD4, which is essential to prostate cancer survival.

While traditional therapies mainly target the androgen receptor alone, many tumors eventually develop resistance by activating alternative pathways that allow cancer to continue progressing. With that knowledge, researchers are evaluating HLD-0915 in clinical trials to assess its safety and effectiveness in slowing tumor growth.

Preliminary data from the ongoing Phase I/II trial demonstrate HLD-0915, a first-of-its kind oral therapy, has a favorable safety profile and significant anti-tumor activity in patients with mCRPC, including patients with extensive prior treatments and adverse molecular features. Among the 22 patients who completed at least two cycles of therapy, 59% achieved a PSA50 response and 32% achieved a PSA90 response. In addition, partial responses were measured by Response Evaluation Criteria in Solid Tumors (RECIST), a standard measure of the effectiveness of cancer treatments. Among all five patients with RECIST-measurable disease at baseline and an on-treatment scan, all achieved a partial response at the first response assessment and a sixth patient with a mixed soft tissue and bone lesion had resolution of soft tissue disease. These encouraging results provide proof of concept for HLD-0915 and support further investigations.

¡°HLD-0915 employs a novel mechanism of action through regulated induced proximity targeting chimera to simultaneously target the androgen receptor and BRD4, which is a critical mediator of prostate cancer progression and therapeutic resistance,¡± said Andrew Hahn, M.D. ¡°Dose expansion studies of HLD-0915 are currently ongoing, and we hope to learn more about its efficacy in the near future.¡±

What is the potential impact for patients with drug-resistant prostate cancer? 

Patients with mCRPC, a form of advanced prostate cancer unresponsive to androgen deprivation therapy, have limited treatment options that often become less effective over time. If results are validated in additional clinical studies, HLD-0915 could offer a new line of treatment.

Furthermore, HLD-0915 received fast track designation from the Food and Drug Administration, accelerating the path from clinical trials to potential approval and access.