Merck ’s vicriviroc for metastatic microsatellite stable colorectal cancer (CRC) saw its Phase Transition Success Rate (PTSR) launch 10 points to 42% after its Phase II trial completed. The PTSR score change occurred on 21 June after updated the trial from active to completed on 17 June. PTSR is the probability, given as a percentage, of a drug progressing successfully from one development stage to the next.

As to its primary endpoints, the 42-patient Phase II (NCT03631407) measured objective response rate, dose-limiting toxicities and adverse events for two doses of vicriviroc, each in combination with Merck’s Keytruda (pembrolizumab), according to Vicriviroc is a C-C Motif chemokine receptor 5 (CCR5) antagonist, which acts against HIV.

The Phase II update also resulted in a four-point bump to the drug’s Likelihood of Approval (LoA), which rose to 17%. LoA is identified via GlobalData’s analysis using a combination of machine learning and its proprietary algorithm and is calculated by compounding the PTSR at each stage the drug is yet to progress through. Both LoA and PTSR can be calculated for a drug by considering characteristics like therapy area, indication and molecule type.

Merck has a market cap of $192.92bn.