Cancer-Focused eFFECTOR Therapeutics Shelves Development Of Lung Cancer Candidate After Disappointing Data

Thursday, eFFECTOR Therapeutics Inc EFTR released topline results from the primary analysis of the Phase 2 KICKSTART trial, which tested tomivosertib or placebo, each combined with Merck & Co Inc’s MRK Keytruda (pembrolizumab), as a frontline treatment for patients with non-small cell lung cancer with PD-L1 ≥50%. 

Based on 36 events, the hazard ratio for progression-free survival (PFS, the study’s primary endpoint) using a stratified Cox proportional hazards model was 0.62 in favor of tomivosertib. 

The two-sided p-value for PFS, based on a stratified log-rank test, was 0.21, which did not meet the pre-specified threshold of p≤0.2. 

The median PFS was 13.0 weeks in the tomivosertib plus pembrolizumab arm and 11.7 weeks in the placebo plus pembrolizumab arm, respectively. Overall survival results remain immature; however, no trend favoring tomivosertib was observed. 

There were 67% Grade 3 or higher treatment-emergent adverse events in the tomivosertib plus pembrolizumab arm versus 37% in the placebo plus pembrolizumab arm.

“While there was evidence of modest tomivosertib activity in the trial, based on the totality of the data currently available, we do not see an obvious path forward to continue developing tomivosertib in frontline NSCLC,” said Steve Worland, president and CEO of eFFECTOR. 

The company said Zotatifin, with its novel mechanism distinct from tomivosertib, is a drug candidate poised to enter a randomized, potentially registrational trial in estrogen receptor-positive (ER+) breast cancer later this year. 

As a next step for the zotatifin program, the company expects to report additional data, including the recommended phase 2 dose (RP2D), for zotatifin combined with fulvestrant and abemaciclib in the second half of 2024. 

In addition, as part of the strategy to leverage investigator-sponsored trials to conserve capital, the company said that a separate, investigator-sponsored trial of tomivosertib in acute myeloid leukemia (AML) will continue unchanged. 

The mechanistic rationale to test tomivosertib in AML is entirely distinct from the rationale in NSCLC and relies on tomivosertib’s potential to inhibit the production of survival proteins Mcl-1 and Bcl-2, which are required for leukemia cell survival.

The company anticipates that its cash, cash equivalents, and short-term investments of over $30 million will be sufficient to fund operations into the first quarter of 2025.

Price Action: EFTR shares are down 78.1% at $3.6 on the last check Thursday.