The Phase 2 OCTOPUS trial, a multicenter randomized clinical trial, has found that adding vistusertib to paclitaxel did not improve treatment outcomes for women with platinum-resistant ovarian high-grade serous carcinoma. The study, which involved 140 participants, aimed to assess whether the combination therapy could prolong progression-free survival and overall survival compared to paclitaxel alone.
The trial's findings, published in the Journal of the American Medical Association, indicated no statistically significant difference between the two treatment arms. In the vistusertib and paclitaxel group, 41% of patients experienced severe side effects, compared to 37% in the paclitaxel-only group. The most common severe side effects included an increased risk of infection and fatigue. Additionally, patients receiving vistusertib reported mild to moderate issues such as acid reflux and skin rash, which were not observed in the placebo group.
Trial Design and Outcomes
The OCTOPUS trial enrolled 140 women, with 70 receiving paclitaxel plus vistusertib and 70 receiving paclitaxel plus a placebo. The primary endpoint was to determine the time until cancer started to grow again. Secondary endpoints included overall survival and treatment efficacy. The trial team found no significant difference between the two groups in any of these measures.
Side Effects and Quality of Life
While most participants experienced at least one side effect, the majority were mild and short-lived. However, the study revealed that 41% of women in the vistusertib arm experienced severe side effects, compared to 37% in the paclitaxel-only arm. Common severe side effects in both groups included an increased risk of infection and fatigue. Quality of life assessments showed no significant difference between the two treatment groups.
Biomarker Analysis and Future Directions
The researchers suggest that future studies should focus on identifying biomarkers that can predict which patients might benefit from vistusertib or similar drugs. Preliminary findings indicated that low levels of PTEN, a potential biomarker, were associated with the time until cancer regrowth in patients treated with paclitaxel and vistusertib. This observation warrants further investigation in separate studies using similar drugs to validate these findings.
