Daraxonrasib for pancreatic cancer: phase 3 survival results

Daraxonrasib for pancreatic cancer produced an unusually large survival difference in patients with metastatic pancreatic ductal adenocarcinoma who had already received one line of chemotherapy. Median overall survival was 13.2 months with daraxonrasib and 6.7 months with standard second-line chemotherapy. That does not mean every patient gained about six and a half months of life. A median marks the point at which half the patients have died and half remain alive, so the accurate statement is that median survival was nearly doubled.

The result comes from RASolute 302, an international, open-label, randomized phase 3 trial. It enrolled 500 patients with previously treated metastatic pancreatic cancer: 248 received oral daraxonrasib at 300 mg once daily and 252 received investigator-chosen chemotherapy. Tumors from 91.8% of participants carried a RAS mutation at codon G12, the most common class of RAS alteration in this disease.

What the head-to-head comparison showed

Across the full trial population, median overall survival was 13.2 months with daraxonrasib versus 6.7 months with chemotherapy. The hazard ratio for death was 0.40. In practical terms, the instantaneous risk of death during follow-up was about 60% lower in the daraxonrasib group. That is not the same as saying that 60% of patients were saved or that every patient lived 60% longer.

The difference was also seen in disease control. Median progression-free survival was 7.2 months with daraxonrasib and 3.6 months with chemotherapy. The objective response rate — the proportion of patients whose tumors shrank enough to meet predefined radiologic criteria — was 31.6% versus 11.2%. The prespecified subgroup with RAS G12 mutations showed a very similar pattern.

For pancreatic cancer, the overall-survival result matters particularly because it goes beyond tumor shrinkage on scans. Overall survival was one of the trial's two primary endpoints and directly measures how long patients live. Median follow-up at the analysis was 8.5 months, however, so longer observation will still be needed to define the durability of the benefit.

Why RAS is such an important target

RAS proteins act like molecular growth switches. Under normal conditions they cycle between an inactive GDP-bound state and an active GTP-bound state. When active, RAS sends signals that promote cell growth and division.

Oncogenic mutations can keep this switch turned on for too long. More than 90% of pancreatic ductal adenocarcinomas carry oncogenic RAS alterations, most commonly in KRAS. That has made the pathway one of the most attractive — and historically one of the most difficult — drug targets in cancer biology.

Daraxonrasib belongs to a newer class of RAS(ON) inhibitors that target the active, GTP-bound form of RAS. Its mechanism is unusual. The molecule first binds the cellular protein cyclophilin A. The resulting complex then binds active RAS and blocks its interaction with downstream signaling proteins. In effect, it prevents RAS from passing on the growth signal that helps sustain the tumor.

Unlike several earlier KRAS inhibitors, daraxonrasib is not designed around only one specific mutation. Its multiselective strategy is intended to cover a broader range of RAS-dependent tumors.

What the trial does not yet establish

These data do not mean there is now a universal “pill for pancreatic cancer.” RASolute 302 enrolled only patients with metastatic pancreatic ductal adenocarcinoma who had already received one line of chemotherapy. The trial does not establish how daraxonrasib performs in localized disease, as first-line therapy, or as treatment intended to prevent recurrence after surgery.

The trial was open-label, so patients and clinicians knew which treatment was being given. That matters less for an objective endpoint such as overall survival than it does for subjective outcomes, but it remains a design feature to keep in mind. The study was also funded by Revolution Medicines, the company developing daraxonrasib.

Toxicity was not eliminated. Grade 3 or higher adverse events occurred in 61.8% of patients receiving daraxonrasib and 69.6% receiving chemotherapy. However, treatment-related adverse events led to discontinuation in only 1.2% of the daraxonrasib group, compared with 11.2% of the chemotherapy group.

At the time of writing, daraxonrasib has not been approved by the FDA. The agency has accepted a New Drug Application for previously treated metastatic pancreatic ductal adenocarcinoma and is reviewing it. The appropriate description today is therefore a strong phase 3 result and a potential new second-line standard, not an already approved standard treatment.

The RASolute 302 result is more precise — and more interesting — than the headline that a pill “doubled life expectancy.” The trial shows that directly suppressing active RAS can produce a substantial survival benefit in one of the hardest cancers to treat, and it demonstrates that effect in a large randomized phase 3 comparison.