Daraxonrasib (RMC-6236) demonstrated antitumor activity and a manageable safety profile across a diverse set of RAS mutations and dose levels in patients with previously treated, RAS-mutated pancreatic ductal adenocarcinoma (PDAC), according to findings from the phase 1/2 RMC-6236-001 trial (NCT05379985) published in the New England Journal of Medicine.1,2
In a subgroup of patients with RAS G12-mutated PDAC receiving daraxonrasib at the 300-mg dose level as second-line therapy (n = 26), the objective response rate (ORR) was 35% (95% CI, 17%-56%). The median duration of response (DOR) in this group was 8.2 months (95% CI, 3.8-not evaluable [NE]), and the median progression-free survival (PFS) and overall survival (OS) were 8.5 months (95% CI, 6.7-10.5) and 13.1 months (95% CI, 10.9-NE), respectively.
Among patients with any RAS mutation (G12, G13, or Q61) treated with 300 mg as second-line therapy (n = 38), the ORR was 29% (95% CI, 15%-46%), the disease control rate (DCR) was 95% (95% CI, 82%-99%), the median PFS was 8.1 months (95% CI, 5.9-10.1), and the median OS was 15.6 months (95% CI, 10.9-NE).
For patients with any RAS mutation treated with the 300-mg dose in the third-line setting or later (n = 45), the ORR was 20% (95% CI, 10%-35%), the DCR was 84% (95% CI, 71%-94%), and the median DOR was 3.3 months (95% CI, 2.8-NE).
“RAS mutations are a central driver of disease across multiple solid tumors, including particularly PDAC. There is significant room for improvement in outcomes over the current standard of care: cytotoxic chemotherapies that are not targeted to these underlying RAS cancer drivers,” Alan Sandler, MD, chief development officer of Revolution Medicines, stated in a news release regarding the publication.2 “These results, along with those from our phase 3 trial, RASolute 302 [NCT06625320], strengthen our confidence in daraxonrasib’s potential to establish an important new treatment option for patients with pancreatic cancer and other RAS-[mutated] cancers.”
Study Highlights
- Treatment with daraxonrasib at the 300-mg dose level in patients with second-line RAS G12-mutated PDAC, any RAS mutation in the second line, and any RAS mutation in the third-line setting or later produced ORRs of 35%, 29%, and 20%, respectively.
- Safety data revealed that 96% of patients experienced TRAEs with the agent; however, the majority were low-grade gastrointestinal or cutaneous issues, and no treatment-related deaths were reported.
- Daraxonrasib is currently being evaluated in 3 phase 3 studies, including the global phase 3 RASolute 303 trial, where its efficacy will be compared with standard-of-care chemotherapy in the second-line setting.
What is the mechanism of action for daraxonrasib?
Daraxonrasib is a first-in-class, noncovalent tricomplex inhibitor designed to target the active, GTP-bound "ON" state of both mutant and wild-type RAS proteins, including KRAS, HRAS, and NRAS.1 By forming a complex with cyclophilin A and RAS(ON), the agent sterically blocks RAS effector binding, thereby suppressing downstream oncogenic signaling. This differentiates daraxonrasib from earlier RAS(OFF) inhibitors, which are often limited by incomplete inhibition or resistance in PDAC, whereas RAS mutations primarily drive constitutive signaling in the GTP-bound state.
How was RMC-6236-001 designed?
This phase 1/2, open-label, multicenter study enrolled patients 18 years of age or older with solid tumors harboring KRAS, NRAS, or HRAS mutations across 16 sites in the US.1,3 In the PDAC cohort, eligible patients had experienced disease progression or unacceptable toxicity after the treatment with fluoropyrimidine- or gemcitabine-based chemotherapy; had an ECOG performance status (PS) of 0 or 1; and had measurable disease per RECIST 1.1 criteria. Exclusion criteria included primary central nervous system tumors, active brain metastases, or impaired gastrointestinal (GI) function.3
Upon enrollment, patients received daraxonrasib at 300 mg orally once daily in 21-day cycles; this was established as the recommended phase 3 dose.1,3
The study’s primary end point was safety and tolerability; secondary end points included ORR, DOR, DCR, and PFS per RECIST 1.1 criteria. Plasma samples at baseline and on-treatment were analyzed for changes in RAS variant allele frequency in circulating tumor DNA.
The current report focused on 168 patients with previously treated RAS-mutated PDAC who received daily oral doses of daraxonrasib at 300 mg or less.1 Baseline characteristics in this population were as follows: