Melanoma: What are your tips about immunotherapy (Keytruda)?

My mother is 96 years old. She was diagnosed with melanoma on the back of her leg just above her ankle in 2024 at the age of 94. Identified as stage 3. When the surgeon went to remove the one spot, she actually identified another and both were melanoma: therefore, declaring stage 3. After surgery Mom began immunotherapy Opdivo. She had two infusions 28 days apart. After the second infusion, she began to break out in a rash. The rash was unbelievable as it eventually covered her entire body. The rash spots began as blisters and progressed into sores scabbing over. If you have ever had a fever blister, it was like fever blisters all over her. It took almost 8 months to get the rash under control. Obviously, she had no more infusions. The manufacturer came back and said the reason for the severe reaction was her age. Here we are now 2 years later and the melanoma is back. Based on my research it appears to be Amelanotic Melanoma as the dermatologist did not suspect it to be melanoma, 3 places biopsied and all 3 melanoma. She will see a surgeon this week for removal, but the oncologist is recommending that she try Keytruda after this surgery. Based on previous reaction with Opdivo, and the major side affect listed for Keytruda, does anyone know if we should expect the same reaction with Keytruda? The rash before was way worse than the surgery and grafting. She was a real trooper, but everyone medically seemed very perplexed at the side affect. For those with Keytruda rash, how bad was it?

@williamfh I had stage 3 melanoma on my shoulder in 2015. Surgery was successful and lymph nodes were removed. This was a year after my breast cancer and radiation.
A little over 5 years later melanoma metastasized in my lung and is inoperable. I started on keytruda in 2021 and will be on it for life. Within the first several treatments no sign of the tumor so there is no doubt Keytruda is a miracle drug.

@rfannin: Thank you for coming to Mayo Clinic Connect to explore your concerns, which are very understandable given the circumstances. I also had amelanotic melanoma that my dermatologist at the time did not suspect to be melanoma. I was subsequently started on Keytruda some years later when I was found to have metastatic melanoma. My first adverse reaction was a small rash which I reported immediately and was readily treated, but it was mild in nature. Individuals react very differently and at different times throughout the treatment cycle to potential adverse events which can occur at any time. While immunotherapy is generally limited to 2 years as no additional benefit has been found beyond that time period, adverse events may continue therefore one must be alert for them.

Rashes can present with varying severity - in your mother's case, it sounded particularly severe so there may be cause to be more cautious when administering and monitoring this PD-1 checkpoint inhibitor. If this is a new medical provider who will be overseeing your mother's care, be sure they're aware of her previous reaction so they're aware of the risk, which may increase the possibilty of it occuring but is not necessarily guaranteed.

Have you discussed this concern directly with her current medical provider?

@grammato3 Thank you for your response. We met this week with the same surgical oncologist who operated on Mom in 2024. She did not treat Mom when she was dealing with the rash; however, we have shared pictures with her. She feels the Keytruda is worth a try (because of it being PDL versus CTL) with no surgical removal at this time. We will meet with Mom’s oncologist next week who had recommended the Keytruda and was the same oncologist Mom had through the Opdivo infusions and the rash afterward. The surgical oncologist and oncologist are conferring before we meet. PET scan results will be part of the discussion. Surgical oncologist also suggested VTEC if there remaining places after Keytruda
None of the dermatologist’s (we saw multiple) or her oncologist had ever seen a rash like she experienced before. She also lost her hair.

@rfannin: it sounds like your mother is in very capable and competent hands. And of course it’s a tremendous help to have you assisting her through this process. I’m wondering if the procedure you’re referring to is possibly T-VEC, a type of immunotherapy that’s a direct injection?
I’m also wondering if any of the past medical professionals suspected something called Steven Johnson Syndrome, which is rare, severe skin rash usually accompanied by blisters. In any event, thankfully it was successfully treated and all remain on heightened alert for such potential this time.

Are you feeling more comfortable with her treatment course now?

@grammato3 Yes, it was T-Vec and it is a direct injection. At one point they did look into the Steven Johnson Syndrome, but ruled it out. As far as comfort level, I think we are all still concerned about the rash. One of my questions will be if it is possible to reduce the amount of Keytruda for the first treatment, and/or extend the time between the first and second treatments. Maybe this could lessen the rash impact if it should occur.

I gather yu declined the immunotherapy after the first cancer, right? That is my situation right now. First melanoma has been surgically removed but was stage III and doctor recommends Keytruda. I am afraid of the side effects b/c of many other medical conditions and am looking for others who have made a choice either way.

@songinmyheart54 Why would you be on it for life? Has it become something you must continue to take to fend off the cancer? So it sounds like it never really eradicated it?

@williamfh
I just saw your comment. In answer to your question.
Melanoma will hide and since this is my second bout of melanoma my oncologist is fearful if I go off keytruda the cancer will come back with vengeance and keytruda may not work a second time. There is no backup plan. Melanoma does not work with chemo and I cant take more than 5-10 mg of prednisone.
Presently in remission.