Johanna C. Bendell, MD
Anti–PD-1 inhibitors are effective in treating patients with microsatellite-instability high (MSI-H) colorectal cancer (CRC), with the FDA approving pembrolizumab (Keytruda) and nivolumab (Opdivo) for use in this setting.
, Bendell, a medical oncologist at Sarah Cannon Research Institute, discussed the current and emerging treatment landscape of immunotherapy for patients with CRC.
OncLive: What are some of the immunotherapy advances in CRC?
: We have seen very exciting data for patients with MSI-H CRC. These are patients who have a higher rate of mutations than others. They are very responsive to immunotherapies. In fact, we have seen FDA approvals of pembrolizumab for patients with MSI-H cancers, as well as nivolumab for MSI-H CRC, which shows what the benefit of these agents can be for these patients with CRC.
There are other combinations that are currently being looked at, but these two are the furthest ahead. There is promise for patients with metastatic MSS CRC to respond to immunotherapies.
Can you highlight the data that we have seen with pembrolizumab in these patients with MSI-H CRC?
We initially saw data for MSI-H CRC with pembrolizumab with response rates above 50%—not only in MSI-H CRC but in other MSI-H tumors, as well. This has subsequently matured and we have seen a response rate between 30% and 40%, which led to the FDA approval of this agent for patients with MSI-H cancers. This was the first time the FDA has ever approved an agent based on a biomarker rather than a tumor type. Hopefully, we will start to see more approvals based on biomarker status.
If the atezolizumab and cobimetinib combination is approved, can you discuss how that will factor in with other available treatments?
The combination of atezolizumab and cobimetinib is for patients with MSS rather than MSI-H disease. The thought is that cobimetinib brings CD8-positive T cells into the tumor to have an immune response, as well as increases the tumor’s expression of MHC class 1, which is a receptor that lets the immune cells recognize the tumor cells better.
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