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IMGN853-0420 — Mirvetuximab + carboplatin → MIRV maintenance in PSOC (FRα+)

Abstract: LBA, Phase 2 · Session: Saturday April 11 / Sunday April 12, 2026 · Simultaneous publication: TBD (Gynecologic Oncology)

Headline: ELAHERE moves earlier — mirvetuximab + carboplatin induction followed by MIRV monotherapy maintenance achieves 68% ORR in the maintenance phase and 63.9% in the PARPi-pretreated subgroup, justifying repositioning of mirvetuximab into platinum-sensitive ovarian (PSOC) including post-PARPi.

At a glance

  • Sponsor: AbbVie (IMGN853-0420; ELAHERE life-cycle program)
  • PI / presenter: Apr 11–12 presentation (presenter TBD)
  • NCT ID: NCT05445778 (IMGN853-0420)
  • Phase / arms / N: Phase 2 single-arm; FRα-high platinum-sensitive recurrent ovarian (PSOC) patients receive MIRV + carboplatin induction → MIRV monotherapy maintenance
  • Primary endpoint(s): ORR in maintenance phase
  • Indication / line: Platinum-sensitive recurrent ovarian cancer, FRα-high (≥75% PS2+ IHC)
  • Comparator: None (single-arm)
  • Session: LBA, Day 2/3

Headline result

81% of patients continued from induction to MIRV monotherapy maintenance. ORR 68% in maintenance phase overall, and 63.9% in the PARPi-pretreated subgroup — the practice-relevant number, because it demonstrates ELAHERE retains activity after PARPi failure. Safety: grade ≥3 neutropenia 15%, blurred vision 10%, thrombocytopenia 10%; pneumonitis 15% over prolonged therapy (monitoring required).

Mechanism / class

Mirvetuximab soravtansine (ELAHERE) is an FRα-directed antibody-drug conjugate with a maytansinoid (DM4) payload, FDA-approved 2022 for platinum-resistant FRα-high recurrent ovarian and full approval 2024. IMGN853-0420 is the AbbVie life-cycle pivot from platinum-resistant into platinum-sensitive.

Trial design deep dive

Study architecture: Phase 2 single-arm, two-stage design — induction phase of MIRV 6 mg/kg (adjusted ideal body weight) + carboplatin AUC5 Q3W for 6 cycles, followed by MIRV monotherapy maintenance Q3W until progression or toxicity. Enrollment restricted to FRα-high (≥75% of viable tumor cells with PS2+ IHC staining intensity) platinum-sensitive recurrent ovarian cancer. No comparator. 81% rollover from induction to maintenance is a key feasibility metric demonstrating the regimen is deliverable.

Endpoint definitions: ORR in the maintenance phase by investigator assessment per RECIST 1.1 (primary, calculated from maintenance-phase start). Secondary endpoints include induction-phase ORR, DOR, PFS, OS, safety per CTCAE v5, and PRO/QoL. The maintenance-phase ORR primary endpoint is unusual — it isolates the monotherapy contribution after carboplatin clearance.

Key subgroup analyses: PARPi-pretreated subgroup (63.9% ORR) is the practice-relevant cohort — establishes ELAHERE retains activity after PARPi failure, the highest-need PSOC niche. FRα IHC intensity (PS2+ ≥75% vs higher cut-offs) reserved for ASCO follow-up. Prior-line and platinum-free-interval subgroups TBD in poster appendix.

Comparator context: No randomized comparator in this Phase 2, but the 68% maintenance ORR substantially exceeds historical PSOC maintenance benchmarks (~30–40% for chemo, niraparib/olaparib in unselected post-platinum). Pneumonitis 15% over prolonged maintenance is the key tolerability concern relative to PARPi maintenance.

FDA implications: Not registration-enabling on its own — supports a Phase 3 PSOC design (likely vs investigator-choice chemo or vs PARPi maintenance in PARPi-naive). The PARPi-pretreated PSOC niche may admit accelerated-approval pathway if Phase 3 is concurrent.

Discussant takeaway

Per AbbVie press and SGO Meeting News coverage: the 63.9% PARPi-pretreated ORR supports moving ELAHERE earlier into PSOC, including in the post-PARPi setting where therapeutic options narrow rapidly. Pneumonitis signal over prolonged maintenance therapy is a key monitoring item.

Practice-changing verdict

Pending — supports Phase 3 design but not yet practice-changing on its own. Likely to anchor a Ph3 maintenance design (similar to GLORIOSA framework) and inform NCCN PSOC sequencing. AbbVie life-cycle for ELAHERE depends on the PSOC move.

  • Other SGO 2026: REJOICE-Ovarian01 (CDH6 ADC platinum-resistant); GLORIOSA / TroFuse-022 / RAINFOL-04 (ADC maintenance Ph3 designs)
  • AACR 2026: FRα ADC mechanism sessions
  • ASCO 2026: Expected dose-cohort and biomarker subgroup follow-up
  • JPM 2026: AbbVie ($ABBV) ELAHERE life-cycle framed at JPM Jan 12–15

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