Eli Lilly has shared phase 1 data on an antibody-drug conjugate (ADC) in platinum-sensitive ovarian cancer (PSOC), shedding light on the company’s chances of competing for a market targeted by rivals including AbbVie and Genmab.
The PSOC cohort enrolled 33 patients to receive sofetabart mipitecan (Sofe-M), an FRα-directed ADC, in combination with bevacizumab. Participants had progressed at least six months after the last platinum dose. Two-thirds of participants had received a PARP inhibitor, such as AstraZeneca’s Lynparza, and about 10% had received AbbVie’s FRα-directed ADC Elahere.
Lilly used the European Society for Medical Oncology (ESMO) 2026 Congress to share data from the trial. On Saturday, researchers revealed a 79.3% response rate in PSOC patients, including a 20.7% complete response rate.
The response rate was consistent across FRα expression levels and prior PARP inhibitor exposure. While the response rate was lowest—66.7%—in the three patients with FRα expression of 0% to 24%, the small number of patients involved makes comparisons challenging. The response rate was almost identical in patients who had and had not received a PARP inhibitor.
Almost 80% of responders remained on treatment as of the ESMO data cutoff. Almost 70% of patients had been on treatment for at least nine months. The median follow-up for progression-free survival (PFS) was 10.2 months. The trial has yet to reach its median PFS.
The most common grade 3 or worse treatment-emergent adverse events were neutropenia and anemia, which affected 42.4% and 24.2% of patients, respectively. The most common adverse events of any grade were nosebleed and nausea, each affecting 72.7% of patients. Researchers described the treatment as well-tolerated. Two patients discontinued because of adverse events.
“The standard of care for platinum-sensitive ovarian cancer has remained unchanged for a decade and demands new treatment options,” Jacob Van Naarden, President of Lilly Oncology, said in a release. “Results for Sofe-M show a promising efficacy and tolerability profile across both platinum-resistant and platinum-sensitive ovarian cancer, regardless of FRα expression levels or prior treatment.”
Lilly started a phase 3 trial of Sofe-M in PSOC one year ago. The PSOC cohorts of the pivotal study are enrolling patients whose disease responded to platinum treatment and remained controlled for at least six months. Participants in the control cohorts are receiving platinum-based doublet chemotherapy plus bevacizumab.
Van Naarden said the latest data “give us confidence as we continue to study Sofe-M in our phase 3 FRAmework-01 program to bring this potential new medicine to the women who need it.”
The study is one of several late-phase clinical trials targeting PSOC. AbbVie, which won FDA approval for Elahere in platinum-resistant ovarian cancer (PROC) in 2022, is running a phase 3 trial in PSOC with an estimated primary completion date of April, according to the federal trials database. The trial is targeting people with high FRα expression, while AbbVie’s rivals, including Lilly, are enrolling broader populations.
Meanwhile, Genmab began a phase 3 PSOC trial of its FRα-directed ADC, rinatabart sesutecan, in April. Last month, AstraZeneca took its FRα-directed ADC, torvutatug samrotecan, into a phase 3 PSOC trial. All the trials are enrolling PSOC patients who relapse after platinum-based chemotherapy.
AbbVie’s Elahere delivers a tubulin inhibitor. The candidates in development at AstraZeneca, Genmab and Lilly all carry topoisomerase I (TOPO-1) inhibitors. Because people may develop resistance to TOPO-1 payloads, potentially limiting sequential use of the rival ADCs, being first to market and becoming the first-choice drug could carry extra value. Genmab has a clear lead in PROC, but the race is closer in PSOC.