1.1 Pembrolizumab is recommended as an option for untreated metastatic colorectal cancer with high microsatellite instability (MSI) or mismatch repair (MMR) deficiency in adults, only if:
pembrolizumab is stopped after 2 years and no documented disease progression, and
the company provides pembrolizumab according to the commercial arrangement.
1.2 This recommendation is not intended to affect treatment with pembrolizumab that was started in the NHS before this guidance was published. People having treatment outside this recommendation may continue without change to the funding arrangements in place for them before this guidance was published, until they and their NHS clinician consider it appropriate to stop.
Why the committee made these recommendations
People with untreated metastatic colorectal cancer that has high MSI or MMR deficiency are usually offered combination chemotherapy including FOLFOX, FOLFIRI or CAPOX. For RAS wild-type cancer, cetuximab or panitumumab is added to FOLFOX or FOLFIRI.
Clinical trial evidence shows that pembrolizumab increases the time until the condition gets worse compared with current treatments. Pembrolizumab may also be more effective at extending life, but the evidence is limited and in the trial people had subsequent treatments that are not available in the NHS. So, it is uncertain how much benefit it offers over a person's lifetime.
There is no evidence from clinical trials that use pembrolizumab for more than 2 years of treatment so the benefit beyond this duration is uncertain.
The cost-effectiveness estimates are within what NICE normally considers an acceptable use of NHS resources. So, pembrolizumab is recommended.