Are you high?

High on microsatellite instability (MSI), that is. Nivolumab monotherapy is an option for metastatic colorectal cancer (mCRC) that is MSI-high or deficient in mismatch repair (dMMR). This is based on recently-published results among the mono-nivo arm of the ongoing phase 2 Checkmate-142 trial. But wherever nivo goes, ipilimumab is not far behind. Last week, results among the Checkmate-142 combo nivo + ipi arm were published, and they’re pretty jaw-dropping. Progression-free survival (PFS) at one year was an impressive 71% among the 119 patients treated with second (and mainly third or fourth) line combo nivo + ipi. That’s compared to 50% PFS at one year achieved with nivo alone (notwithstanding a non-randomized comparison). The grade 3-4 toxicity rate was 32%, favorable compared to that seen with melanoma, again perhaps due to the ipi dose being only 1 (not 3) mg/kg. Pending ongoing phase 3 data, this will maybe translate into the new standard for MSI-H/dMMR mCRC which will definitely have Bristol-Myers Squibb flying high as a kite.