DOI: 10.1097/01.COT.0000493057.26194.c5
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Issn Print: 0276-2234
Publication Date: 2016/08/25
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Excerpt
Walter Stadler, MD, FACP, the Fred C. Buffett Professor of Medicine and Surgery, Chief of the Section of Hematology/Oncology, and Director of the Genitourinary Program at University of Chicago Medicine, lead a discussion at the 2016 ASCO Annual Meeting on analyzing the definitive study of nivolumab in refractory renal cell cancer.
“It's an interesting discussion because the two groups investigated data from the same clinical trial but came to very disparate conclusions. The organizers gave me the title of Treatment Beyond Progression: Forward Progress or Simply Progression Confirmed? Now, the question in front of us is whether there is any value to treatment beyond progression of patients with metastatic renal cell cancer who are on therapy with nivolumab beyond standard RECIST-based criteria,” Stadler explained.
“The thought process here is that with pseudoprogression the growth we see on CT scans really reflects inflammatory infiltrate,” he clarified. “This eventually leads to tumor shrinkage and is a concept that has been around since initial investigations with CTLA-4 inhibitors and is also observed with PD-1 inhibitors.”
The trial under Stadler's discussion lead to FDA approval of nivolumab for renal cancer in the refractory setting. Patients were allowed to be treated beyond the standard RECIST-based progression. The FDA analysis focused only on five patients who had an initial progression and then had a response. He said it explained the difference between the 14 percent response rate beyond progression reported as a bottom line by the sponsor, who also analyzed patients whose best RECIST response was stable disease or response and 3 percent by the FDA. In either case, he recognized the number of patients affected by treatment beyond progression is small.
Stadler pointed out that the patients on treatment beyond progression were on treatment longer than those who were not treated beyond progression in the sponsor's analysis. Yet, he noted probable bias in the statistical comparison as physicians selected patients for ongoing therapy who they believed would do well. Therefore, he concluded treatment beyond progression does not necessarily lead to improved outcomes.
