On July 30, 2025 Vivace Therapeutics, Inc., a small molecule discovery and development company developing first-in-class cancer therapies targeting the Hippo pathway, reported that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation to VT3989 for the treatment of mesothelioma in the United States (Press release, Vivace Therapeutics, JUL 30, 2025, View Source [SID1234654656]). VT3989, the company’s first-in-class and best-in-class transcriptional enhanced associate domain (TEAD) autopalmitoylation inhibitor, is a novel investigational small molecule cancer therapeutic that is designed to target the Hippo pathway by inhibiting palmitoylation of members of the TEAD protein family.
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"The granting of Orphan Drug Designation to VT3989 underscores the critical need for new, effective therapies for mesothelioma, an aggressive cancer with limited treatment options. The benefits provided by this important designation will support our continued advancement of VT3989, which has already generated compelling clinical trial data, a first for this promising therapeutic class," said Sofie Qiao, Ph.D., president and chief executive officer of Vivace Therapeutics. "We are committed to continuing clinical development of VT3989 and discussing a move into a registrational Phase 3 study in mesothelioma with FDA by the end of 2025."
VT3989 has been evaluated in more than 200 patients to date in an ongoing, open-label Phase 1 clinical study and, to the company’s knowledge, is the first and only member of the TEAD autopalmitoylation inhibitor class for which compelling clinical efficacy data have been publicly reported. In addition to the promising data to date, VT3989 has demonstrated a positive safety profile in the Phase 1 trial, which supports its best-in-class potential.
Clinical findings for VT3989 have been particularly notable in patients with mesothelioma who have failed chemotherapy and immuno-oncology combination regimens, which represent the only approved therapies in this indication. These results will be presented at a major medical conference in the second half of 2025.
Orphan Drug Designation is granted by FDA and is intended to support the development and evaluation of treatments for rare diseases affecting fewer than 200,000 people in the U.S. The designation provides drug developers with potential benefits including tax credits for qualified clinical trials, exemptions from certain FDA fees for clinical trials, and the potential for seven years of market exclusivity following drug approval.
About Phase 1 study of VT3989
The Phase 1 study of VT3989 (View Source) is a multi-center, open label trial designed to evaluate the safety, tolerability, pharmacokinetics (PK) and biological activity of VT3989 in patients with refractory metastatic solid tumors, including refractory pleural and non-pleural malignant mesothelioma.