FDA grants fast track designation to HLD-0915 in mCRPC

The FDA has granted fast track designation (FTD) to HLD-0915, an investigational bifunctional small molecule therapy for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC), Halda Therapeutics announced in a news release.¹

FTD is awarded to novel agents that are intended to treat or prevent serious conditions and have the potential to address an unmet medical need. With this designation, the development process for HLD-0915 can benefit from more frequent engagement with the FDA as well as eligibility for accelerated approval and priority review.

“We are pleased HLD-0915 has been granted Fast Track designation by FDA for patients with mCRPC,” said Christian Schade, president and CEO of Halda Therapeutics, in the news release from the company.¹ “Fast Track designation is an important step forward as we work to advance this program through clinical development and, ultimately, to bring a novel, highly selective, oral-based treatment option to patients living with this challenging disease.”

According to the company, preclinical data in prostate cancer models showed that “orally delivered HLD-0915 treatment resulted in tumor shrinkage and declines in prostate-specific antigen (PSA), while delivering a favorable therapeutic index including in models of drug resistance.”

The agent is currently being evaluated in a phase 1/2 trial (NCT06800313) in patients with mCRPC who have progressed on prior lines of therapy.² In total, the open-label study plans to enroll 33 adult patients across clinical trial sites in the US.

To be eligible for enrollment, patients must have an ECOG performance status of 0 to 1; a life expectancy of at least 3 months; and adequate hematological, renal, and hepatic function. Additionally, patients must have prior orchiectomy and/or ongoing androgen deprivation therapy and a castrate level of serum testosterone.

The study is being conducted in 2 parts. In phase 1 of the trial, participants will receive escalating doses of HLD-0915 to determine the maximum tolerated dose and/or recommended phase 2 dose (RP2D) level(s). Phase 2 of the trial will then further assess the safety, tolerability, and initial anti-tumor activity of HLD-0915 administered at the RP2D level(s).

In both phases, HLD-0915 will be administered as a single agent on a 21-day treatment cycle. Patients will continue on treatment until disease progression or study discontinuation.

The primary outcome measures for phase 1 include the frequency of dose-limiting toxicities and the frequency and severity of adverse events (AEs) and serious AEs. Phase 1 will also assess pharmacokinetic parameters as well as efficacy end points such as PSA decline, objective response rate, duration of response, and radiographic progression-free survival, all assessed at 21-day follow-up.

Final study completion is anticipated for March 2027.

REFERENCES

1. Halda Therapeutics receives FDA Fast Track Designation for HLD-0915 for the treatment of metastatic castration-resistant prostate cancer. News release. Halda Therapeutics. August 14, 2025. Accessed August 14, 2025. https://haldatx.com/halda-therapeutics-receives-fda-fast-track-designation-for-hld-0915-for-the-treatment-of-metastatic-castration-resistant-prostate-cancer/

2. A study of HLD-0915 in patients with metastatic castration resistant prostate cancer (mCRPC). ClinicalTrials.gov. Last updated April 6, 2025. Accessed August 14, 2025. https://clinicaltrials.gov/study/NCT06800313