Pembrolizumab

Hi JenBob 

I was treated with pembrolizumab for metastatic triple negative breast cancer in 2023. It put my cancer into remission but also caused issues. I had no side effects at all until I had a significant ‘adverse event’ about 5 months in which manifested as an acute kidney injury and loss of thyroid. I needed 9 months steroids starting at a very high dose to resolve my kidney issue. During the wean from the steroids it also became apparent I had pneumonitis. I had to stop treatment due to the severity of all of this, but the drug had already significantly reduced my mets. What was left ( the mets were in my liver ) was probably just scar tissue but I had it ablated  as a precaution. I have had no evidence of disease since then. My kidney function eventually recovered. I will need to take synthetic thyroxine for life. My lungs now look clear on a scan but I don’t have the fitness I had. The steroids have also left their mark.

It’s one of those drugs that can be a game changer, but serious adverse events do occur for some people. Given its mechanism of action I suspect there’s correlation between it working well, and it doing some collateral damage. 

Would I take it if I had my time again? Absolutely. It almost certainly saved my life and I didn’t have other options. And all the after effects are manageable and much better than where I would probably be if I hadn’t had the treatment. 

I don’t know whether your husband has been given an explanation of how pembrolizumab works, but it’s worth understanding it as it helps explain why sometimes things go wrong when people are treated with this drug. It’s an immune checkpoint inhibitor used on tumours that express something called PD-L1. In normal life The PD-1 protein on our T cells binds to PD-L1 on critical organ cells to create immune privileged zones where essentially the immune system leaves the organ alone. His cancer and my cancer are mimicking that method in order to hide from the immune system. It’s like the cancers are wearing an invisibility cloak that stops the immune system destroying damaged cells.

Pembrolizumab breaks this binding so the immune system can ‘see’ and take action on the tumour. Whilst it doesn’t work for everyone, it can work extremely well.  

The downside is the immune system might also damage normal cells. The vast list of side effects in the literature are these sorts of things, ranging from things that are easy to fix, like skin rashes, to actual organ damage. They come on quite suddenly - my oncologist told me you will have no side effects from pembro unless and until one day you become suddenly very ill.

Hi codfish

Thank you for replying, my husband had his first cycle on Friday and when they mention side effects they just frighten me and I worry of what's to come as this is his second time with throat cancer, like you he didn't have a choice as without treatment he was given 6 to 12 months and chemo would only extend his life by 4 months so here we are and have started immunotherapy although I have read some good stories and although you have had issues you have come out of it living your life and it's good to hear that if you had your time again you would have the treatment again, that's so positive

All the best for the future x

The important thing is to start steroid treatment quickly if something goes wrong. If he finds something doesn’t feel quite right, he needs to contact his oncology unit and they will assess him quickly. When my issue started I was lucky I had had a blood test earlier in the day ahead of the next treatment cycle I should have had the following day. It showed extremely high levels of creatinine and the hospital admitted me just as the dehydration symptoms were starting. I then immediately accepted steroids as I knew it would be necessary rather than waiting another 24 hours to see what happened. 

I'm keeping a diary to note any changes and so far he's ok , it's the unknown that's scary