FDA-Approved Cancer Drug Epcoritamab Misses Overall Survival Endpoint in Confirmatory Phase 3 Trial

In a significant setback for a widely used lymphoma therapy, the bispecific antibody epcoritamab (marketed as Epkinly) has failed to significantly extend overall survival in its confirmatory Phase 3 trial. Genmab and AbbVie clarified that the EPCORE DLBCL-1 study missed its sole primary endpoint for the United States, casting uncertainty over the drug's regulatory future in the country.[1][2]

Epcoritamab was granted accelerated approval by the U.S. Food and Drug Administration in 2023 for adults with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) who have received at least two prior lines of systemic therapy. The accelerated pathway allows drugs for serious conditions to reach the market based on surrogate endpoints—in this case, early response rates. However, drugmakers are required to conduct confirmatory trials to prove that these early responses translate into definitive clinical benefits, such as patients living longer.[1][4]

The EPCORE DLBCL-1 trial enrolled 483 patients globally who were ineligible for autologous stem cell transplantation. Participants were randomized to receive either subcutaneous epcoritamab monotherapy or an investigator's choice of standard chemoimmunotherapy regimens. The trial was designed with prespecified primary endpoints that differed by region, with overall survival designated as the sole primary measure of success for the U.S. market.[2]

While the drug demonstrated a 26 percent reduction in the risk of disease progression or death—achieving a median progression-free survival of 3.5 months compared to 3.0 months for standard therapy—it fell short on the ultimate metric. The overall survival hazard ratio was 0.96, meaning there was no statistically significant difference in how long patients lived between the two study arms.[1]

Despite the overall survival miss, the trial did yield positive secondary signals. The complete response rate was notably higher in the epcoritamab arm, at 38 percent versus 26 percent for the control group. Furthermore, responses appeared durable for those who achieved them, with 59 percent of complete responders maintaining their remission at the 36-month mark.[1]

The disconnect between improved progression-free survival and stagnant overall survival is a known challenge in modern oncology trials. In heavily pretreated populations, patients who progress on a study drug often cross over to receive other novel therapies, which can dilute the measurable survival benefit of the initial experimental treatment. The trial was also conducted during the peak of the Omicron variant of the COVID-19 pandemic, which introduced additional mortality variables into the heavily immunocompromised patient cohort.[1][4]

The failure to meet the U.S. primary endpoint places epcoritamab in a precarious regulatory position. The FDA has grown increasingly strict regarding accelerated approvals that fail their confirmatory trials, frequently convening advisory committees to determine whether such drugs should remain on the market, have their indications narrowed, or be withdrawn entirely.[4]

Genmab and AbbVie have emphasized that they will engage with global regulatory authorities to discuss the totality of the data and determine the next steps. The companies are not abandoning the therapy; epcoritamab continues to be evaluated in earlier lines of DLBCL and in combination regimens. It also recently secured an additional FDA approval for relapsed or refractory follicular lymphoma, supported by a separate trial that successfully met its endpoints.[3][5]

For patients and oncologists, the immediate clinical impact remains complex. Epcoritamab is an off-the-shelf bispecific T-cell engager, offering a more accessible alternative to personalized CAR-T cell therapies, which require complex manufacturing and specialized treatment centers. Until the FDA makes a formal determination, the drug remains available, but oncologists may increasingly weigh the lack of a proven survival benefit when sequencing treatments for advanced lymphoma.[4]