Dr. Tammaro. The PBM in collaboration with the POP Advisory Board, are developing different levels of evidence to support the use of targeted medications identified to be potential therapy in those diagnosed with a point mutation. Even if a medication does not have an FDA approval, it has to have some evidence to support its use in a particular cancer. If you identify a point mutation or biomarker in a patient and provide evidence to supports its use within that particular disease state, the VA pharmacy could approve its use based off of that evidence. VA pharmacy would not require an actual FDA approval for that indication.
What the VISNs, PBM, and precision oncology are trying to do is determine the level of evidence that we have to support or approve use of a targeted therapy. We are definitely moving forward and changing the horizon on how we actually treat our patients after they’ve gone through first-line therapy. We are trying to figure out where these point mutations come in, the line of the therapy, and how we actually treat these cancers. Pharmacy is making a step forward in conjunction with Michael Kelley, MD, the National Program Director for Oncology, Specialty Care Services, whose group is establishing those guidelines.
Dr. Bauml. I don’t mean to downplay the difficulty of that process. This is a huge, difficult process. One only needs to look at the long line of failed trials looking at PI3 kinase inhibitors to show that just knowing that a mutation exists does not necessarily mean that a targeted therapy works in that space.
Drawing that line is really complicated, both within the VA and, indeed, outside of the VA. It’s a really complicated process, and understanding the implications of different mutations is only going to get more complicated. Of course, now we have things like NTRK and even rarer genetic aberrations that are going to affect not only lung cancer, but also a wide range of malignancies.
Promising Research
Dr. Bauml. The pathways that are emerging as clear driver mutations for which we have available therapies, at least within lung cancer, are MET exon 14, RET, and NTRK. I am also intrigued by the emerging data in the HER2 space.
Dr. Das. The other therapy that has been getting a lot of press is immunotherapy, of course. And I’ve been seeing many really good responders to immunotherapy within the veteran population that I treat. It is felt that degree of PD-L1 expression correlates with responsiveness to the immune check point inhibitors that are being used in lung cancer, and we are tending to see higher rates of PD-L1 expression in patients who are prior or current smokers who have a higher overall tumor mutation burden.
I see patients both at Stanford and at the Palo Alto VA, and I have noticed that the patients that I have been treating at the VA tend to have higher levels of PD-L1 expression with better responses to the immunotherapy drugs, probably because most of the VA patients are former or current smokers. And, another interesting observation is that these veteran patients are, for whatever reason, having a lower incidence of some of the autoimmune AEs seen with these immune checkpoint inhibitors. I have been keeping an eye out for more data and information to support these observations I have had in my clinical practice and I specifically attended ASCO this year to learn more about what others have seen and studied with immune check point inhibition in lung cancer. We are learning now that PD-L1 is not a perfect marker for predicting response to the checkpoint inhibitors and the other immunotherapeutic agents, and there is a great deal of research going on to try to figure out what other biomarkers could be useful and which patients are most likely to benefit from these drugs.
I was excited to hear about the combination of nivolumab and ipilimumab that is being tested in both mesothelioma and in small-cell lung cancer where we really don’t have as many treatment options as we have in non-small cell lung cancer. That data was quite exciting, and interestingly, there does not seem to be a correlation with PD-L1 expression and responsiveness to treatment with the immunotherapeutic agents in those histologic subtypes. The story is still unfolding, and we await additional data to help guide us in our treatment decisions.
Dr. Tammaro. Immunotherapy is the new fad in oncology. We have just scheduled our first patient for first-line therapy due to PD-L1 tumor proportion score is > 50%. Recently, at ASCO KEYNOTE-021 researchers looked at using pembrolizumab in combination with carboplatin plus pemetrexed chemotherapy for first-line metastatic non-squamous NSCLC. The research suggested that patients treated with pembrolizumab + chemotherapy continued to derive a higher overall response rate and progression free survival when compare with those on chemotherapy alone despite a low or no PD-L1 tumor expression.
