We have recently read the great success President Carter has had from his treatment with SRT and Keytruda. What determines whether an ALK+ lung cancer patient changes to pembrolizumab for 2nd line therapy versus other therapies once the patient has acquired resistance on crizotinib?
Sun, 12/13/2015 - 21:35
Keytruda (pembrolizumab) is only approved in patients whose tumor tissue expresses PD-L1, and the specific test for this defines positive expression as 50% or greater level. It is an option for patients who have this level of expression and have previously received and progressed on prior treatment. However, it is worth noting that the response rates to immune checkpoint inhibitors such as Keytruda in patients with activating mutations like EGFR or ALK have tended to be low -- it's not to say that responses are never seen, but they are less common in such patietns than in many other patients with lung cancer. It's also important to underscore that President Carter has melanoma, which is not the same as lung cancer, so it would be a mistake to make clinical devisions for one person based on the results of a single patient with a totally different cancer.
In addition, it's worth noting that there are two second generation FDA approved ALK inhibitors now approved to be given after crizotinib. Both Zykadia (ceritinib) and the just-approved Alecensa (alectinib) are highly active. In addition, chemotherapy can be quite effective in patients with an ALK rearrangement, and Alimta (pemetrexed) may be especially so.
This isn't to say that an immune checkpoint inhibitor can't or absolutely shouldn't be used as a second line therapy, but rather that it's a mistake to presume that just because one person with melanoma happens to do well with immunotherapy means that it's the best choice for other people with a wide range of other cancers. There are many very effective treatment options for ALK-positive NSCLC, many better studied and commonly recommended in this setting.
Wed, 12/16/2015 - 14:08
Thank you Dr. West, you have totally clarified what was recently reported all over the news about President Carter's success story. Very happy for him, and amazIng going through all that at 91!