I’m sorry to hear this for Matt and you. Yes, by all means check out the ADC trial but they have an 8-12 week post IPI waiting period.
Also have your doctor immediately call the NIH concerning TIL. It’s rather grueling (but so is IL-2 by itself) but when it works, it’s very effective. If your husband is young and in good physical condition, he may be a good candidate.
Concerning IL-2, its response rate by itself is low (~15% but with a well documented 5-6% complete response rate). There is also some suggestion I’ve seen that it works better when given about 4-6 weeks after IPI but I’ve seen no studies or trials concerning it.
Finally, get radiation for the mets on his vertebrae. This is a palliative treatment (pain avoidance) and insurance should cover it.