Kura Oncology Inc. reported durable clinical activity for its experimental combination of darlifarnib and cabozantinib in patients with advanced clear cell renal cell carcinoma (ccRCC), presenting updated Phase 1a data from the FIT-001 trial at the 2026 Kidney Cancer Research Summit in Boston. The results, disclosed on July 27, 2026, show an objective response rate ranging from 33% to 50% across evaluated dose levels and a median progression-free survival (PFS) of 13 months in pre-treated, cabozantinib-naïve patients. This data supports the potential for darlifarnib to enhance vascular endothelial growth factor receptor (VEGFR)-targeted therapies in second- and third-line settings, where treatment options remain limited after prior immunotherapy.

The clinical data compares favorably with historical benchmarks for tyrosine kinase inhibitor (TKI) and hypoxia-inducible factor-2 alpha (HIF-2α) monotherapies. More than half of the patients remained on treatment at the data cut-off, indicating sustained benefit. The safety profile was manageable and consistent with the known profiles of the individual agents, with neutropenia successfully managed through dose interruptions and supportive care after the initial dose-limiting toxicity period.

Clinical Trial Results

The findings are derived from the ongoing FIT-001 clinical trial (NCT06026410). Key metrics from the cabozantinib-naïve cohort and the broader safety population are detailed below.

Mollie Leoni, M.D., Chief Medical Officer of Kura Oncology, stated that the data informs the dose combinations advancing into the randomized Phase 1b portion of FIT-001. She noted that cabozantinib-naïve patients represent an increasingly important population as cabozantinib is often reserved for later lines of therapy following immunotherapy-based regimens.

What the Numbers Show

The durability of response is a notable feature of these early-stage results. With the median duration of response not estimable at most dose levels due to multiple ongoing responses, the data suggests that the combination may offer prolonged disease control compared to standard monotherapies. This is particularly significant in the refractory setting, where prior exposure to immune checkpoint inhibitors and VEGFR-targeted therapies has limited subsequent efficacy options. The ability to maintain more than half of the patients on treatment at the cut-off date indicates that the combination tolerability allows for continuous dosing, which is critical for maintaining therapeutic pressure on the tumor.

Next Steps and Investor Event

Kura Oncology is currently enrolling patients in the U.S. and E.U. for the randomized Phase 1b dose-optimization portion of FIT-001. This segment evaluates darlifarnib plus cabozantinib versus cabozantinib alone to select a recommended Phase 3 dose for a planned registrational study in 2028.

The company hosted a webcast and conference call on July 27, 2026, at 5:00 a.m. PT / 8:00 a.m. ET, featuring management and Adanma Ayanambakkam, M.D., M.S., Assistant Professor of Hematology Oncology at the Stephenson Cancer Center, University of Oklahoma Health Sciences Center. Dr. Ayanambakkam highlighted that the response rates are encouraging given the limited options in this pretreated population, noting that continued follow-up will further define the durability of benefit.

Kura Oncology, Inc. will present updated Phase 1a results from the ongoing FIT-001 Phase 1a/1b clinical trial evaluating darlifarnib in combination with cabozantinib in advanced renal cell carcinoma (RCC) at the 2026 Kidney Cancer Research Summit (KCRS) in Boston. The presentation will feature long-term follow-up results in heavily pretreated cabozantinib-naïve patients with refractory RCC, providing further evidence of darlifarnib’s potential as a combination agent with VEGFR-targeted therapies. RCC is the most common form of kidney cancer, with clear cell RCC (ccRCC) accounting for more than 61,000 new cases in the U.S. annually.

The FIT-001 trial (NCT06026410) is a Phase 1a/1b study assessing the safety and efficacy of darlifarnib plus cabozantinib in advanced RCC. The updated Phase 1a data is expected to support darlifarnib’s potential to enhance VEGFR-targeted therapy in ccRCC. A global randomized Phase 1b study comparing darlifarnib plus cabozantinib versus cabozantinib alone is currently ongoing.

Key Trial Details

The results continue to support darlifarnib as a precision combination agent across multiple targeted therapy classes. Kura Oncology has scheduled a virtual investor call on July 27, 2026, at 5:00 a.m. PT / 8:00 a.m. ET to discuss the updated data.