Mirvetuximab Soravtansine Combo Elicits Antitumor Activity in Platinum-Sensitive Ovarian Cancer

Mirvetuximab soravtansine-gynx (Elahere) combined with carboplatin showed antitumor activity and a manageable safety profile in patients with recurrent platinum-sensitive ovarian cancer, according to findings from the phase 2 IMGN853-0420 trial (NCT05456685) presented at the 2026 SGO Annual Meeting.¹

The trial met its primary end point, with the folate receptor alpha (FRα)-targeted antibody-drug conjugate (ADC) mirvetuximab soravtansine plus carboplatin reaching an objective response rate (ORR) of 62.7% (95% CI, 52.6%-72.1%) after 6 cycles in the subset of patients with ≥50% FRα expression. In the overall population (≥25% FRα expression), the ORR was 62.4% (95% CI, 53.3%-70.9%) at the end of the combination phase and rose to 68.0% (95% CI, 59.1%-76.1%) across the total study period, which included a mirvetuximab soravtansine monotherapy continuation phase. The median duration of response for the overall population was 11.2 months (range, 8.6-13.9).

Notably, 91% of patients experienced a reduction in target lesion size during the combination phase, and 81% continued to single-agent mirvetuximab soravtansine without progressive disease, maintaining or deepening their initial responses.

The median progression-free survival was 11.0 months for both the ≥50% FRα expression subset (95% CI, 9.8-13.7) and the overall population (95% CI, 9.8-13.1).

A subgroup analysis showed that mirvetuximab soravtansine plus carboplatin maintained efficacy regardless of prior PARP inhibitor (PARPi) exposure. The ORR was 72.6% in PARPi-naïve patients and 63.9% in those previously treated with a PARPi.

“IMGN853-0420 is the first trial to show combinability of an ADC with carboplatin in ovarian cancer,” said presenting author Gottfried E. Konecny, MD, Department of Medical Oncology, University of California Los Angeles Medical Center, Los Angeles, CA. “Responses were achieved in a clinically representative population comprising about 50% PARPi-exposed patients typically characterized by reduced responses to subsequent platinum-based chemotherapy,” added Konecny.

Safety Profile of Mirvetuximab Soravtansine Plus Carboplatin

The safety profile of the combination was generally consistent with the known toxicities of the individual agents. The most common treatment-related adverse events (TRAEs) included blurred vision (78% overall; 8% grade ≥3), corneal events (71%; <1%), dry eye (68%; 5%), and nausea (62%; 2%). Hematological toxicities were also prevalent, with thrombocytopenia occurring in 50% (10% grade 3) and neutropenia in 49% (15% grade 3) of patients.

Ocular events were primarily low-grade and reversible in more than 90% of patients. Hematological toxicities were most prevalent during the combination phase; the incidence of any-grade thrombocytopenia dropped from 50% to 10% when patients transitioned to mirvetuximab soravtansine monotherapy, and no bleeding events or febrile neutropenia were reported.

Adjudicated treatment-related pneumonitis occurred in 19 patients (15.2%), with 11.2% being grade 1/2. While 2 deaths (1.6%) were attributed to pneumonitis, both occurred in patients with underlying cardiopulmonary disorders. Overall, 11 of the 19 patients with pneumonitis were able to be successfully retreated with mirvetuximab soravtansine.

Study Design and Baseline Characteristics

The IMGN853-0420 trial was a global, single-arm, phase 2 study evaluating MIRV (6 mg/kg adjusted ideal body weight) plus carboplatin (AUC 5) administered every 3 weeks. After 6 to 8 cycles, patients without progressive disease continued with MIRV monotherapy until progression or unacceptable toxicity. Eligible patients had high-grade serous epithelial ovarian cancer and had received 1 prior line of platinum-based chemotherapy.

The study enrolled 125 patients in the overall population (≥25% FRα expression), with a subset of 102 patients having high expression (≥50% FRα expression). The median age for both groups was 65 years (range, of 33-87). All patients (100%) across both cohorts presented with high-grade serous carcinoma histology. In the total population, primary diagnoses included ovarian cancer in 58.4% (n = 73), fallopian tube cancer in 32.8% (n = 41), and primary peritoneal cancer in 8.8% (n = 11); the ≥50% FRα subset showed a similar distribution of 55.9% (n = 57), 34.3% (n = 35), and 9.8% (= 10), respectively.

Regarding BRCA status in the total population, 17.6% (n = 22) had a BRCA1 or BRCA2 mutation, 77.6% (n = 97) were wild type, and 4.8% (n = 6) were unknown; in the ≥50% FRα subset, 14.7% (n = 15) had mutations, 80.4% (n = 82) were wild type, and 4.9% (n = 5) were unknown.

All 125 patients had prior carboplatin and taxane exposure, while 4.0% (n = 5) of the total group and 4.9% (n = 5) of the ≥50% FRα subset had received prior cisplatin. Previous PARPi therapy was reported for 48.8% (n = 61) of the total population and 47.1% (n = 48) of the ≥50% FRα subset, and prior bevacizumab (Avastin) use occurred in 27.2% (n = 34) and 26.5% (n = 27), respectively. The primary platinum-free interval (PFI) was >12 months for 60.0% of the total population and 56.9% of the ≥50% FRα subset, while a PFI of 6 to 12 months was observed in 39.2% and 42.2% of the respective groups.

Next Steps

Mirvetuximab soravtansine-gynx is approved by the FDA for the treatment of adult patients with FRα-positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer, who have received 1 to 3 prior systemic treatment regimens.²

The results of the IMGN853-0420 trial reported at the SGO meeting support expanding the use of the ADC to patients with FR-expressing platinum-sensitive ovarian cancer. Ongoing research in this area includes a phase 2 trial exploring mirvetuximab soravtansine plus carboplatin in the neoadjuvant setting for patients with newly diagnosed FRα-expressing advanced-stage serous epithelial ovarian, fallopian tube or primary peritoneal cancer (NCT06890338).³

REFERENCES

1. Konecny GE, Lim PC, Santin AD, et al. Mirvetuximab Soravtansine Plus Carboplatin in Folate Receptor Alpha-Expressing Recurrent Platinum-Sensitive Ovarian Cancer. Presented at: 2026 SGO Annual Meeting; April 10-13, 2025; San Juan, Puerto Rico.

2. FDA approves mirvetuximab soravtansine-gynx for FRα positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer. Published March 22, 2024. Accessed April 13, 2026. https://tinyurl.com/2nc43jzs

3. ClinicalTrials.gov. A study to assess anti-tumor activity of intravenously (IV) infused carboplatin with mirvetuximab soravtansine in participants with newly diagnosed folate receptor alpha (FRα)-expressing advanced-stage serous epithelial ovarian, fallopian tube, or primary peritoneal cancer. Identifier: NCT06890338. Updated January 26, 2026. Accessed April 13, 2026. https://clinicaltrials.gov/study/NCT06890338