I am now 6 weeks into my Pembrolizumab/ NAB-Paclitaxel combo. The treatment is proving relatively straightforward. Slightly achy at times and bowel issues in the form of wind and frequency of movement but not diarrhoea. If I take ibuprofen, omeprazole and buscopan at the appropriate times, it’s all very manageable. Energy levels and ability to perform mental tasks ok, but ability to run any distance rapidly diminishing.
I met my oncologist for a review today and she seems happy with my ability to tolerate the treatment and with my stable blood results. She has authorised the next 6 weeks of treatment and has put in requests for the next round of CT and liver MRI scans to come towards the end of that block. I am not expecting to learn much at that stage, as the tumours are likely to look larger either way - if the Pembrolizumab is working for me, the tumours will be infiltrated with T cells which will make them seem larger; and if it’s not working for me, they will be larger anyway. The following round of scans (probably after another 12 weeks of treatment) will be more informative.
I found a much more detailed breakdown of the results of KEYNOTE-355 (the clinical trial that led to the authorisation of this regime for metastatic TNBC with a ‘combined positive score’ (CPS) > 10%) on Merck (the manufacturer)’s website for medical professionals. It made it a bit easier to join together the data on overall survival, progression free survival, and complete and partial response rates, than the headline e information I had seen elsewhere. Just over half the patients in the pembro plus chemo arm who had a CPS>10 had an objective response to the treatment, and half were still alive (presumably broadly the same half) at 2 years. Unfortunately longer term survival isn’t great with only 30% of the CPS>10 group still alive at the end of the trial (44 months). The trial entry criteria required a good performance status (ie ability to live a fairly normal life) bit didn’t restrict to people with a low cancer burden at the start of the trial. It therefore doesn’t seem possibly to stratify the results by how extensive the cancer was at the start. My ‘expert’ contact tells me it is more effective where people only have a small number of metastases, as I currently do.
I have no intention of asking for my oncologist’s view of my prognosis, but it’s going to be highly linked to whether the second scans show an objective response to the treatment. If not, I imagine I will be taken off the pembro and escalated up to the current last chance saloon for mTNBC, the attractively named sacituzumab govitecan, an immunotherapy/chemo conjugate that attacks the TROP-2 protein typically present on TNBC. By all accounts it’s a fairly punishing treatment and I rather hope I don’t need to get to experience it. If I can last out a few more years there might be better things around; I will be watching the ModIfy trials with interest as my cancer is within its scope.
