Merck’s patritumab-dxd case strengthens

Daiichi Sankyo's Merck-partnered ADC patritumab deruxtecan, recently rejected by the FDA on a technicality, is heading back to the regulators. The companies said yesterday that the confirmatory Herthena-Lung02 trial had met its primary endpoint, showing a "statistically significant" improvement over chemo on progression-free survival. Overall survival data are still immature. Merck and Daiichi filed patritumab-dxd, a HER3-targeting ADC, for accelerated approval in third-line or later EGFR-mutated NSCLC, based on the phase 2 Herthena-Lung01 trial, but received a complete response letter in June over third-party manufacturing issues. Now the project looks set for a full approval, assuming that these issues are resolved and data from Herthena-Lung02 pass muster. Details are under wraps for now, but some investors might wonder about the companies' statement lacking the phrase "clinically meaningful". There were also two fatal cases of interstitial lung disease, Merck said. If patritumab-dxd does get the nod it will become the first HER3-directed ADC to reach the market; although plenty of other groups are active here, Merck and Daiichi are well ahead, despite the delay. Rivals include Bristol Myers Squibb, through its deal with SystImmune, and BioNTech, which recently restarted a trial of its MediLink-originated contender following toxicity concerns.

Notable trials of patritumab deruxtecan

Source: OncologyPipeline & clinicaltrials.gov.