For those patients who do not have any of those targetable gene alterations, we will go ahead and send for next-generation sequencing through POP, which allows testing of a much broader gene panel. Those results can take about a month or so to come back. I usually don’t wait for these results in order to get someone started on treatment. For patients without EGFR, ALK, or ROS1 found on initial testing, I will go ahead and start them on IV systemic chemotherapy. It is often very useful when you do get the next-generation sequencing results back, since in almost all cases, a gene alteration can be detected and is provided in the accompanying report. In a large subset of lung cancer cases, a gene alteration is seen in KRAS, for which we still do not have an effective targeted therapy. Despite this, I still find it useful to obtain the results because we generally feel that the driving genetic alterations occur mutually exclusive of one another. When we do see KRAS reported from a patient’s tumor specimen, we’re not generally looking for other types of mutations, so I find it helpful to know what is the alteration that is driving the growth of a patient’s tumor. The trend moving forward is to perform next-generation sequencing on all tumor specimens regardless of tumor type or histology, which can hopefully enable us to get to the bottom of what the driving genetic alteration is and to see if there are any targeted treatment approaches that can be offered to the patient.
In a few lung cancer cases, I have seen alterations in HER2 and BRAF that have been detected and reported using a next-generation sequencing platform. Just recently the FDA approved the BRAF-directed therapies of dabrafenib and trametinib for patients with lung cancer who are found to have a BRAF V600E mutation. It is hoped that as the FDA continues to provide approvals for targeted drugs in patients with lung cancer, the VA formulary will be able to offer these therapies to our veteran patients with the ultimate goal of providing treatment that has increased efficacy and less toxicity compared to conventional IV chemotherapy.
One of my frustrations earlier on was when we did find these more rare targetable mutations, I would run into problems with the VA formulary in allowing me to prescribe certain targeted therapies. In many cases, if the drug was not FDA-approved for lung cancer, I was told that I couldn’t use it and would have to go through the appeal process, which was quite onerous. Moving forward, we are seeing more and more data and trials with newer targeted agents in lung cancer, leading to new FDA approvals. With these approvals, I think it will be easier to be able to offer these targeted therapies to our patients.
Dr. Bauml. One of the issues that arises when we’re discussing even the FDA-approved therapies, is that many of these targeted therapies are relatively rare, and they’re especially rare amongst veterans. Now others have mentioned BRAF and HER2, and these do have some overexpression and mutations that occur among smokers. But the more common targetable genetic aberrations, EGFR, ALK, and ROS1 are more common amongst never-smokers. Given the high prevalence of tobacco use among veterans, these changes are rare. The incidence of ALK translocation is 3% to 7%. The incidence amongst veterans is likely much lower than that, given the tobacco abuse—to the point that I actually had a patient who had an ALK translocation; and of course, I prescribed the patient crizotinib. This was prior to the ALEX Trial and alectinib data. I prescribed crizotinib and was told it wasn’t on the formulary. Initially I was surprised, but when I said, “Well, look, when was the last time someone within our VA has prescribed crizotinib?” The answer was never.
This is the difficulty: As we enter this era of molecularly targetable therapy, the way we structure our formularies and the way that we review these data is going to have to change. This year at the American Society of Clinical Oncology (ASCO) meeting there were some very exciting lung cancer abstracts that evaluated ado-trastuzumab emtansine, which is an antibody drug conjugate currently approved for the treatment of HER2 overexpressing breast cancer. The abstracts showed response rates of up to 40% in lung cancer with the administration of this drug in HER2-mutated lung cancer. The HER2-amplified still had a response rate of 20%, which given the toxicity profile of this agent, is quite appealing. Being able to explore these early phase studies, as was described through the personalized medicine pathway, is, a great step forward for VA care.