FDA’s March 13, 2017 approval of ribociclib concerned a specific use: initial endocrine-based therapy with an aromatase inhibitor for postmenopausal women with HR-positive, HER2-negative advanced or metastatic breast cancer. For this March 16 retrospective, the approval letter establishes that authorization; the accompanying March 2017 label explains the trial behind it. [209092Orig1s000ltr][209092s000lbl]
MONALEESA-2 assigned 668 patients at random to two equally sized groups. One received ribociclib and letrozole; the other received placebo and letrozole. Both groups therefore received letrozole. The study was double-blind, and its main efficacy measure was investigator-assessed progression-free survival. It was not a comparison against a different CDK4/6 medicine. [209092s000lbl]
The interim analysis favored ribociclib on that measure. Median progression-free survival had not been reached in its group, versus 14.7 months in the comparison group. “Not reached” does not mean every patient remained free of progression indefinitely. More importantly, a progression-free result cannot be substituted for overall survival: the label said those data were immature, with 6.5 percent of participants having died. [209092s000lbl]
The letter separately recorded a sponsor commitment to submit later interim and final overall-survival analyses. That commitment identifies additional evidence to seek, not a result already available on March 16. Readers assessing a claim about longer life would need the relevant survival analysis, rather than relabeling the disease-control finding. These two documents share one approval chain; neither turns this historical explanation into current prescribing advice or evidence of cure. [209092Orig1s000ltr][209092s000lbl]
Source documents
- NDA 209092: KISQALI approval letterhttps://www.accessdata.fda.gov/drugsatfda_docs/appletter/2017/209092Orig1s000ltr.pdf
- KISQALI (ribociclib) initial US prescribing informationhttps://www.accessdata.fda.gov/drugsatfda_docs/label/2017/209092s000lbl.pdf