Recommendation for best cancer hospital?

We’re currently dealing with a difficult situation, as my husband’s melanoma has spread despite initial treatments. Currently he is being seen at University of Michigan, but initial immunotherapy wasn’t working, (keytruda) and the next option is a combination immunotherapy, (yervoy & opdivo) which only has a 30% chance success rate. We want to explore all our options and are looking for recommendations for the best cancer hospitals or treatment centers, especially those with expertise in melanoma and advanced immunotherapy treatments.

If anyone has personal experiences or knows of highly regarded hospitals or specialists, we would greatly appreciate your insights.

Thank you in advance for your help.