Chemotherapy and immunotherapy

Hi Annmancot 

I am one of the community champions on the breast cancer forums. I can see you have already joined our triple negative breast cancer forums. I recommend you also join our Breast cancer forum as it’s far busier than the one specific to tnbc, but used by people with tnbc as well as the other breast cancers. I have metastatic tnbc and if you click on my name you can see my story.

I am guessing you are about to have pembrolizumab with 4 cycles of paclitaxel and carboplatin and then with 4 cycles of EC? My route into it was slightly different as it was originally thought to be an early stage tnbc as it was small and I had no lymph node involvement. So I had 4 cycles of EC and 12 weeks of paclitaxel. During this, they found it had spread to my liver so I then had pembrolizumab alongside more paclitaxel (NAB-Paclitaxel this time). 

Immunotherapy works in a very different way to chemotherapy. Chemo destroys cells somewhat indiscriminately so you get lots of side effects because of that. Principally chemo has effects on your blood counts, your gut and your hair. For me it was fatigue / achiness, diarrhoea, loss of taste and hair loss.

Pembrolizumab is a PD-1 inhibitor, so it removes the PD-1 protein from your body. My understanding is that PD-1 normally binds with another protein called PD-L1 to create immune privileged zones in your body. It effectively puts Harry Potter’s invisibility cloak around your endocrine system and other critical organs to protect them from the immune system. The variant of tnbc that I have (and that you have if you are being offered pembro) has PD-L1 proteins in it and is using this pathway to hide away from the immune system. So pembro breaks the bind and allows your immune system to ‘see’ the cancer. The idea is to let the immune system tackle the cancer, helped by the chemo it’s served up with. It can work very well indeed. It put my cancer into remission which has remained stable. 

The answer to the question of whether immunotherapy has different side effects to chemotherapy is therefore a mixed one. It often doesn’t have many side effects at all, but it can have very sudden and very significant consequences because the immune system is in effect over stimulated. These can be very wide ranging and I don’t think there’s any way of predicting exactly what might happen. I had some skin issues early on but then lost thyroid function and had an acute kidney injury. During treatment for that it became apparent I also had pneumonitis. In terms of managing side effects from immunotherapy the important thing is to react to anything that seems unusual as early steroid treatment reduces the inflammation involved. The way my oncologist put it is if one of these immunotherapy related adverse events happens, you will feel really well until you suddenly feel unwell. She told me never to wait to see if it improved over the next few days, but to contact my oncology 24 hour number. 

Thank you for the information x