Zev Wainberg, MD
A number of clinical trials have been examining the potential of immunotherapy agents in the field of gastric cancer, though several questions remain regarding what role this type of therapy could actually have.
, Zev Wainberg, MD, an assistant professor of Medicine at UCLA and co-director of the UCLA Gastrointestinal Oncology Program, discusses a plethora of immunotherapy agents, such as pembrolizumab (Keytruda), durvalumab, avelumab, and apatinib, for the treatment of patients with gastric cancer, as well as a number of ongoing clinical trials in this space.
OncLive: Can you discuss the clinical trial you're involved in with pembrolizumab?
That has been studied in several different settings, including the third-line setting, for which preliminary evidence of activity has already been presented in small patient numbers at previous meetings. That data has been reported now a few times, with response rates and some of the activities of this agent in a group of patients who have not historically responded very well. These are the third-line typical patients, or advanced patients with metastatic gastric cancer.
We have, to my knowledge, at least 3 very large studies looking at pembrolizumab in gastric cancer. These are 3 very large, international trials with about 100 patients each trials.
Thus far, does it seem like a promising agent in this space?
I think the hints of activity in these small groups suggest that it is promising, or this group of therapies is promising. It remains to be seen who these patients are; certainly not a large number of them, but rather the minority of them, do respond. There is this group of patients that respond, and these things really need to be reproduced in a much larger set of data to be confident that it's real.
Has PD-1 positivity been investigated in this space?
That's one of the factors, and PD-L1–positive staining is one of the criteria for at least 2 of the trials that I mentioned. It hasn't been worked out to the extent that it has in lung cancer, and we don't even know, to be fair, what percentage of patients are PD-L1–positive in gastric cancer. It is one of the criteria that are used, and on some level, there does seem to be this suggestion that if one doesn’t have staining of the antigen, the likelihood of the response is very low.
What about PD-L1 agents? Do you see potential for that class of drugs?
On some level, there have already been reported results from the JAVELIN trial with avelumab, and there have been reported results of durvalumab with gastric cancers. We're seeing a little more than anecdotal responses in this group of patients that have 10% or 20% responses. I don't think it's going to be pembrolizumab that's going to produce the responses here. I think if it's a true phenomenon in gastric cancer, and we've already seen it with nivolumab as well, then it won't be these one or two drugs. It's going to be across the board.
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