Interesting posters from ASCO

Prof Toon Van Gorp discusses three highly interesting posters. 

The first poster is about a study combining cemiplimab with an HPV16 vaccination (ISA101b) as a therapeutic vaccine for cervical cancer. This phase 2 study included 113 patients treated with 350 mg of cemiplimab every three weeks, along with three injections of the vaccine. The study lacked a control arm, focusing solely on the combination therapy. About 50% of patients were PD-L1 positive. The ORR was 17%, with PD-L1 positive patients showing a slightly higher ORR of 22%, compared to 13% in PD-L1 negative patients. In comparison, the ENGOT-cx9 (EMPOWER) study, which used cemiplimab monotherapy, reported an ORR of 16%. Median OS was 13 months for the combination therapy, slightly higher than the 12 months observed with cemiplimab monotherapy. Median PFS was three months in both studies. These results suggest that the combination of cemiplimab and ISA101b does not significantly improve outcomes compared to cemiplimab alone, indicating the need for further investigation.

The second poster discusses the ENGOT-ov55 (MIRASOL) study, which evaluated mirvetuximab soravtansine versus investigator-choice chemotherapy in patients with ovarian cancer. This subanalysis focused on patients older than 65 years. Among the 453 total patients, 199 were over 65, with 107 receiving mirvetuximab and 92 receiving chemotherapy. The median PFS for mirvetuximab in older patients was 5.7 months, comparable to 5.6 months in the total population. In the chemotherapy arm, the median PFS was 3 months for older patients versus 4 months in the overall population. Notably, median OS for older patients was significantly better with mirvetuximab (20 months) compared to chemotherapy (12 months), a more substantial difference than observed in the total population (3.5 months). The safety profile was consistent, with fewer grade 3 adverse events, serious adverse events, and discontinuations in the mirvetuximab arm. Thus, mirvetuximab shows good efficacy and safety in older patients, potentially offering even better outcomes than in the overall study population.

The third abstract reviews data on mirvetuximab soravtansine from four studies: the first-in-human study, the phase 2 SORAYA study, the FORWARD I study, and the MIRASOL study, encompassing 682 patients. The focus was on patients with a median overall survival of more than 15 months, including those with low, medium, and high expression of the folate receptor alpha (FRα). While the majority of patients were FRα-high expressers (79%), 20% were medium and 1% were low expressers. The ORR in this long-survivor group was 56%, higher than the 42% in the MIRASOL study, indicating a correlation between early response and prolonged survival. However, eye toxicity was more common among long responders, suggesting the need for dose adjustments. No specific subcategory of patients could be identified in advance as long responders, but a quick and early response appears to be a positive indicator. Other toxicities, such as neuropathy and gastrointestinal issues, were similar across studies. This suggests the potential to expand mirvetuximab use to patients with medium and low FRα expression, though careful management of eye toxicity is necessary for long-term treatment.