MacroGenics' Cancer Drug Margenza Flops On Overall Survival Analysis

  • MacroGenics Inc MGNX scored a big win with its full approval for anti-HER2 drug Margenza in December 2020 based on a head-to-head matchup with breast cancer med Herceptin. 
  • But Margenza's overall survival (OS) data could spell a rough road ahead for the drug.
  • Margenza, after chemo, failed to significantly extend the lives of patients with advanced HER2-positive breast cancer after two or more lines of prior therapy compared with Roche Holdings AG's RHHBY Herceptin. 
  • Margenza plus chemo posted a median OS of 21.6 months compared with 21.9 months for patients in the Herceptin-chemo arm. 
  • In December, the FDA gave Margenza, a HER2/neu receptor antagonist, a full approval based on PFS data from the Phase 3 SOPHIA study, wherein Margenza posted a 24% reduction in risk of disease progression or death over Herceptin, with a median PFS of 5.8 months for MacroGenics' drug.
  • In a subpopulation of patients with a CD16A allelic variation, Margenza posted a numerical OS benefit over Herceptin (23.3 months versus 20.8 months), but those results weren't significant. That subgroup comprised 82% of the trial's 536 patients.
  • Just one subgroup hit the statistical significance mark. 
  • In a small subgroup of CD16A patients who were homozygous for the F-allele at position 15, Margenza posted a median OS of 23.6 months compared with 19.2 months for the Herceptin arm.
  • MacroGenics estimated that subgroup represents around 40% of all patients in its target indication and 38.5% of patients in this study.
  • Price Action: MGNX stock dropped 9.96% after hours to $19.61 on Tuesday.

Posted In: breast cancerBriefsPhase 3 TrialBiotechNewsHealth CareSmall CapMoversTrading IdeasGeneral

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