The Role of Biomarker Testing in Anal Cancer

Cathy Eng, MD, FACO, FASCO, the David H. Johnson chair in Surgical and Medical Oncology, co-leader of the Gastrointestinal Cancer Research Program, professor of Medicine (Hematology and Oncology), co-Director of GI Oncology, vice-chair of SWOG GI Committee, and the director of the VICC Young Adult Cancers Initiative at Vanderbilt-Ingram Cancer Center discusses how biomarkers are being explored to aid the treatment of anal cancers.

Biomarkers in the anal cancer space is an area of active research, explains Eng. The biomarker with the most research currently is PD-L1 expression, which first showed promise in other solid tumors as a predictor of response to immune checkpoints inhibitors. More research is needed in the field.

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0:08 | The role of biomarkers is largely exploratory. The 1 biomarker that's been most heavily explored is obviously PD-L1 expression, which has been explored in multiple other malignancies where immune checkpoint inhibitors are being considered. For anal carcinoma, keeping in mind this is a rare cancer, the original data regarding pembrolizumab [Keytruda], noted that there was still benefit in patients that were PD-L1 overexpresses versus those that were not. Then, in our original trial looking at nivolumab [Opdivo] in the refractory setting, a smaller study, but also we were not selective and did not require PD-L1 expression to participate in the trial, we still had patients that were also responders. Once again, the numbers are much smaller, because we're a rare patient population. We hope to derive, hopefully more data in the future, moving forward with looking at immune checkpoint inhibition.

1:11 | I do not believe biomarkers are being utilized fully in the space because I think, in large part, funding has been an issue. There has been data that was created or attempted to be created from the INTERACT trial, which I also participated in. And that was basically limited to select sites because of limited funding. Same story, when we wrote up our ETCTN trial, we had limited funding as well. And only we were able to basically evaluate samples from patients that we treated at MD Anderson Cancer Center. Ironically enough, currently in our phase 2 randomized study, MCI 9673 part b, although we actually have funding this time around, I think a lot of patients are more interested in circulating tumor DNA, just because of the convenience, rather than providing a tissue sample even though we actually were able to obtain funding this time. So, I'm a little concerned although we don't have the final numbers. I'm a little concerned about the number of tissue specimens we were hoping to achieve from our randomized phase 2 study. So, I think moving forward, based upon all the phase 1-3 trials that have been created, I hope we will be able to derive more information and I'm hoping that similar information will be derived from all these individual studies so that we can learn something cumulatively.