"These numbers compared favorably to [CheckMate-214], indicating the value of having a regimen where there was a defined treatment endpoint," says Michael B. Atkins, MD.
In this video, Michael B. Atkins, MD, discusses the HCRN GU16-260-Cohort A trial, which looked at nivolumab plus ipilimumab in advanced clear cell renal cell carcinoma. The findings were presented at the 2023 ASCO Genitourinary Cancers Symposium in San Francisco, California. Atkins is the deputy director of the Georgetown Lombardi Comprehensive Cancer Center in Washington, D.C.
The HCRN GU16-260 trial was a trial of nivo monotherapy, followed by a ipi boost in patients who didn't respond or had pressive progressive disease in patients with treatment naive, clear cell metastatic kidney cancer. We published the results of this trial in Journal of Clinical Oncology in April of 2022, but we wanted to look at a correlative endpoint in this study, which was treatment free survival. Immunotherapy has the property of being able to continue disease control after treatment stops. Also, sometimes toxicities continue after treatment stops. This endpoint – treatment free survival – can characterize both this treatment free period and the toxicity during this period.
We've looked at this in other studies in patients with melanoma and kidney cancer receiving immune therapy, and saw that there was significant treatment free survival on the immunotherapy arms. But it was compromised by the fact that the in those studies, treatment was discontinued only for progression or toxicity rather than a defined treatment endpoint. So, we wanted to look at that in this trial, because treatment stopped at 96 weeks maximum. We updated that trial data through 37.7 months and had 128 patients enrolled, and that's what we're reporting on.
What we first looked at was the response rates. In this treatment, we included Part A and Part B as 1 regimen. The response rate overall was 36%. It was 58% in the favorable risk population, and 27% in the intermediate and poor risk population. We saw that 68% of patients were still alive at the 3-year time point, and 38% of patients were free from subsequent therapy. All patients had completed treatment.
We then wanted to look at treatment free survival, which we defined as the area between the time to event curves for treatment initiation to stopping treatment, and treatment initiation to the beginning of subsequent treatment. What we saw for the overall study looking over a 36-month period, was that 30 months of that time were spent alive, and that was divided up as 11.5 months on treatment, 9 months treatment free, [and] 9.5 months on subsequent therapy. For the favorable risk patients, 12.9 months were spent treatment free and 99% of time was spent alive, with there being only 1 death at 28 months in the favorable risk patients. For the intermediate and poor risk patients, 22% of the 36-month period was spent treatment free. We then compare those numbers to what we reported in the CheckMate-214 study on the ipilimumab/nivolumab arm. These numbers compared favorably to that study, indicating the value of having a regimen where there was a defined treatment endpoint.
This transcription has been edited for clarity.