A phase 3 prostate cancer trial of Candel’s oncolytic virus has met its primary endpoint, sending the stock up more than 200%. The phase 3 hit was however offset by the failure of a midphase study buried deeper within its trial win release.
On that win: Investigators enrolled 745 people with intermediate-to-high risk, localized prostate cancer. All patients underwent standard-of-care external beam radiation therapy. Two-thirds of participants also received an injection of CAN-2409, an adenovirus encoding an enzyme, into the prostate plus an oral prodrug of valacyclovir. The rest of the patients received placebo and the prodrug.
Candel linked its candidate to a 14.5% relative improvement in disease-free survival (DFS), an endpoint that looked at cancer recurrence or death from any cause. The improvement caused the study to hit its primary endpoint.
The biotech saw the 14.5% improvement after 54 weeks and, on a conference call to discuss the data, Candel chief medical officer Garrett Nichols, M.D. said “the DFS difference increases over time beyond” that point. The biotech previously said the endpoint would look at DFS 24 months after the last patient was treated.
The primary endpoint hasn’t been used in prior trials and may not be accepted by regulators, the biotech said last month. Hopes that the FDA will accept the endpoint are underpinned by a special protocol assessment (SPA) that Candel agreed with the FDA.
The biotech said Wednesday that the study was conducted under a SPA “on key aspects of study design.” Candel cited the agreement as evidence that the data could support a filing for approval. The biotech said last month that it made “minor amendments to the protocol” without forming a new agreement with the FDA.
Candel plans to seek approval in the fourth quarter of 2026 and has enough cash to fund operations until the end of the first quarter of 2025. The biotech’s share price opened up 200% at close to $14, bolstering its ability to raise money.
The difference in the rate of DFS events, 22.8% in the treatment arm versus 30.5% in the control, was underpinned by the frequency of positive biopsies and treatment failures. Positive biopsies favored the study drug by 13.5% to 20.5%. The treatment failure figures for CAN-2409 and placebo were 3.0% and 4.4%, respectively.
There was a higher death rate in the treatment arm, 6.3%, than the control group. 5.6%. But none of the deaths in either group were deemed related to prostate cancer. Two patients died of prostate cancer but they were counted among the participants with disease recurrence. Candel linked its therapy to a 38% reduction in the risk of prostate cancer recurrence or prostate cancer-related death.
Candel slipped news of a phase 2b failure into the CAN-2409 press release. In that study, 190 people with low-to-intermediate risk localized prostate cancer took CAN-2409 while undergoing active surveillance. The trial found the intervention had no statistically significant effect on the time to radical treatment and the percentage of patients with prostate cancer-free biopsies one year after treatment.