Immunicum’s allogeneic dendritic cell vaccine ilixadencel has failed to better the 18-month survival rate achieved by Pfizer’s Sutent in a phase 2 metastatic renal cell carcinoma (mRCC) trial. As of the cutoff, 63% of patients in the ilixadencel arm were alive compared to 66% in the Sutent cohort.
The 18-month overall survival rate is one of two co-primary endpoints in the midphase trial. The second primary endpoint covers overall survival, but, with more than 60% of patients in both arms still alive, the study is yet to generate the data needed to properly assess how ilixadencel compares to Sutent by that yardstick.
Despite missing one primary endpoint and being on track to miss the second, Immunicum’s release to disclose the data hailed the results as positive. That interpretation of the data rests on the rate of complete responses in the two arms of the trial.
Five of the 45 newly diagnosed mRCC patients who received an intratumoral injection of ilixadencel on top of Sutent experienced a complete response. That resulted in a complete response rate of 11%. The rate among the 25 patients who received Sutent as a monotherapy was 4%.
In its statement, Immunicum claimed “the most important outcome was achieving 5 complete responses ... without ilixadencel adding toxicity.” However, complete response rate is absent from the list of 15 outcome measures on the ClinicalTrials.gov listing for the study. The list does feature measures related to objective and tumor response rates, but they aren’t primary objectives.
Immunicum acknowledged that the complete responses were unexpected, but, buoyed by the data, it plans to push past the failure to improve overall survival and work to establish ilixadencel as an off-the-shelf primer of the immune systems of solid tumor patients.
“The surprising number of complete responses in advanced-stage cancer patients is particularly encouraging and highly supportive of our vision for ilixadencel as a backbone therapy in modern cancer treatment regimens,” Immunicum CEO Carlos de Sousa said in a statement. “We are eager to conduct the full analysis of the data and use that to refine and accelerate ilixadencel’s clinical development.”
Shares in Immunicum fell 9% following the release of the top-line data.