Arena and Eisai Announce Results of Re-Adjudication of Rat Mammary Tumors from Lorcaserin Carcinogenicity Study

Arena Pharmaceuticals, Inc. ARNA and Eisai Inc. announced today results from a Pathology Working Group's re-adjudication of female rat mammary tumor diagnoses from a two-year rat carcinogenicity study of lorcaserin. Arena convened the PWG in response to the lorcaserin Complete Response Letter, which questioned the certainty of the female rat mammary tumor classifications. The PWG reviewed relevant tissues and reported that mammary fibroadenomas (benign tumors) were distinguishable from mammary adenocarcinomas (malignant tumors). The PWG reported shifts in the numbers of both tumor types from the initial report included in the lorcaserin New Drug Application and that adenocarcinomas were no longer numerically higher than the control group in the lorcaserin low- and mid-dose groups.