It sort of depends on what you define as success. The goal was never to "cure" the cancer, rather, to shrink the tumor.

I hesitate to assign an exact percentage to the effectiveness since there are so many factors to consider, but I remember Keytruda being reported to shrink tumors in less than a third of patients who took it.

The goal is to cure, from the article, quoting the head of lung at Yale:

> “Chemotherapy has limitations. Immunotherapy has the ability to cure. I lead the Yale lung team. We have patients on these immunotherapies alive more than eight years.”

I am sorry, that wasn't clear; That was the goal in the specific case of my family-member. The tumors would never fully disappear, and he would likely need more treatments later on.