Martin LP, et al. – Researchers distinguished folate receptor alpha (FRα) expression in archival and fresh biopsy tumor samples from relapsed ovarian cancer patients. In view of the concordance of FRα expression in biopsy versus archival tumor samples, they indicated that archival tissue could reliably identify patients with receptor–positive tumors. Moreover, it was appropriate for patient selection in mirvetuximab soravtansine clinical trials. An association was observed between higher FRα expression and a greater antitumor activity, regardless of the tissue source analyzed.

Methods

• In this study, patients with ovarian tumors amenable to biopsy were eligible to enroll.
• A minimum requirement of FRα positivity in archival tumor samples (≥ 25% of cells with ≥ 2 + staining intensity) was the eligibility criteria.
• Mirvetuximab soravtansine at 6 mg/kg once every 3 weeks was administered to patients.
• They gathered core needle biopsies before and after treatment and FRα levels assessed by immunohistochemistry.
• The association between receptor expression and response was summarized by descriptive statistics.

Results

• This study incorporated twenty-seven heavily pre-treated patients.
• As per observations, six individuals (22%) did not have evaluable pre-treatment biopsies due to insufficient tumor cells.
• 71% was the concordance of FRα expression in archival and biopsy tissues.
• There were no major shifts in receptor expression in matched pre- and post-treatment biopsy samples.
• Moreover, adverse events were generally mild (≤ grade 2) with keratopathy (48%), fatigue (44%), diarrhea, and blurred vision (each 37%) being the most common treatment-related toxicities.
• Including two complete responses and four partial responses, the confirmed objective response rate (ORR) was 22%.
• Results revealed superior efficacy measures in the subset of patients with the highest FRα levels (ORR, 31%; progression-free survival, 5.4 months).