FDA Grants Fast Track Designation to Pan-KRAS Inhibitor KST-6051 in KRAS-Mutant Solid Tumors

The FDA has granted fast track designation to KST-6051, an oral pan-KRAS inhibitor, for the treatment of patients with advanced or metastatic solid tumors harboring KRAS mutations.¹

The designation was supported by the agent’s preclinical data package. KST-6051 is designed to inhibit KRAS in both its GTP-bound (active) and GDP-bound (inactive) states and has demonstrated antitumor activity across multiple preclinical tumor models, according to its developer, Kestrel Therapeutics.¹ The company intends to advance KST-6051 across KRAS-driven cancers, including pancreatic ductal adenocarcinoma (PDAC), colorectal cancer (CRC), and non–small cell lung cancer (NSCLC), and it is currently being evaluated in the first-in-human phase 1 FALCON trial (NCT07458347) in patients with advanced solid tumors harboring KRAS mutations.^1,2

“FDA fast track designation for KST-6051 is an important regulatory milestone for Kestrel, based on the strength of our preclinical data package,” Frank Haluska, MD, PhD, president and chief executive officer of Kestrel Therapeutics, stated in a news release.¹ “This designation will allow us to work more closely with the FDA as we advance KST-6051 through our ongoing Phase 1 study, with the goal of bringing a much-needed treatment option to patients with KRAS-mutant tumors as efficiently as possible”

How is the phase 1 FALCON trial designed?

KST-6051 is being evaluated in the first-in-human, open-label, multicenter phase 1 FALCON dose-escalation study, which is enrolling an estimated 145 adults with advanced or metastatic KRAS-mutant solid tumors.^1,2

Eligible patients must be at least 18 years of age with histologically documented locally advanced unresectable or metastatic NSCLC, PDAC, CRC, or another solid tumor with a documented KRAS mutation.² Disease progression on or intolerance to standard therapy, an ECOG performance status of 0 or 1, measurable disease per RECIST 1.1 criteria, and adequate cardiovascular, hematologic, hepatic, and renal function are also required.

Patients who received prior RAS or KRAS inhibitors or have central nervous system tumors or metastases are excluded.

KST-6051 is being evaluated at escalating doses across sequential patient cohorts in 21-day cycles.

Primary end points are the incidence of dose-limiting toxicities through the end of cycle 1 and the frequency of treatment-emergent and treatment-related adverse effects (AEs). Secondary end points include pharmacokinetic parameters, and efficacy outcomes including objective response rate, disease control rate, duration of response, and progression-free survival.

References

1. Kestrel Therapeutics receives FDA fast track designation for KST-6051, a potential best-in-class pan-KRAS inhibitor, in the treatment of KRAS mutant advanced solid tumors. News release. Kestrel Therapeutics Inc. September 15, 2026. Accessed September 15, 2026. https://kestreltherapeutics.com/wp-content/uploads/2026/09/KestrelTx-Fast-Track-Press-Release.pdf
2. A first-in-human phase 1 dose-escalation study evaluating the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of KST-6051 in patients with advanced or metastatic solid tumors with a KRAS mutation. ClinicalTrials.gov. Accessed September 15, 2026. https://clinicaltrials.gov/study/NCT07458347