The efficacy and safety of mirvetuximab soravtansine in FRα-positive, third-line and later, recurrent platinum-sensitive ovarian cancer: the single-arm phase II PICCOLO trial

BACKGROUND: Mirvetuximab soravtansine-gynx (MIRV) is a first-in-class, folate receptor alpha (FRα)-targeting antibody-drug conjugate with United States Food and Drug Administration approval for FRα-positive platinum-resistant ovarian cancer. PICCOLO is a phase II, global, open-label, single-arm trial of MIRV as third-line or greater (≥3L) treatment in patients with FRα-positive (≥75% of cells with ≥2+ staining intensity) recurrent platinum-sensitive ovarian cancer (PSOC). PATIENTS AND METHODS: Participants received MIRV (6 mg/kg adjusted ideal body weight every 3 weeks) until progressive disease (PD), unacceptable toxicity, withdrawal of consent, or death. Primary endpoint was investigator-assessed objective response rate (ORR). Key secondary endpoint was investigator-assessed duration of response (DOR). Additional endpoints included investigator-assessed progression-free survival (PFS), overall survival (OS), and safety. Analyses of subgroups by disease characteristics (e.g. platinum-free interval) and treatment history [e.g. prior bevacizumab and poly (adenosine diphosphate [ADP]-ribose) polymerase inhibitor (PARPi) treatment] were exploratory. RESULTS: Seventy-nine participants were enrolled and efficacy assessable. The primary endpoint was met; ORR was 51.9% [95% confidence interval (CI) 40.4% to 63.3%]. Median DOR was 8.25 months (95% CI 5.55-10.78 months) and median PFS was 6.93 months (95% CI 5.85-9.59 months). OS was not mature at data cut-off. ORR was 45.8% (95% CI 32.7% to 59.2%) in participants with PD while on/within 30 days of prior PARPi (n = 59) and 60.0% (95% CI 14.7% to 94.7%) in those without PD with prior PARPi (n = 5). No new safety signals occurred; most common treatment-emergent adverse events (TEAEs) were gastrointestinal, neurosensory, and resolvable ocular events. TEAEs led to discontinuation in 13 participants (16%) and death in 2 participants (3%). CONCLUSIONS: MIRV as ≥3L treatment in heavily pretreated recurrent FRα-positive PSOC demonstrated notable efficacy and tolerable safety, including among those with prior PD on or within 30 days of PARPi (NCT05041257).