High-dose interleukin 2 (HD IL-2, aldesleukin) immunotherapy benefits patients in all International Metastatic RCC Database Consortium (IMDC) criteria risk categories when used to treat metastatic renal cell carcinoma (mRCC), according to an analysis of data from the PROCLAIM registry (ClinicalTrials.gov Identifier: NCT01415167).1 Patients in the IMDC poor-risk category do not benefit as much as other patients.

“These data show that in the appropriately-selected population, HD IL-2 can be very effective therapy,” said Michael Hurwitz, MD, PhD, assistant professor of medicine (medical oncology) at the Yale Cancer Center in New Haven, Connecticut. “I am not surprised by the findings but I am reassured by them — that there is still a role for HD IL-2 in the appropriate patients.”

“This is still a work in progress but it’s definitely exciting,” said Pavlos Msaouel, MD, PhD, department of genitourinary medical oncology at The University of Texas MD Anderson Cancer Center in Houston, who noted that newer versions and formulations of IL-2 are currently in development.2-4

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“I think that with the HD IL-2 and the modified versions of IL-2 therapy, the exact proportion of patients that will benefit from treatment in the era of immune checkpoint inhibitors remains to be determined,” Dr Msaouel said. “This paper shows that regardless of the IMDC prognostic group criteria, as long as patients fulfill certain physiologic criteria — meaning they have a good performance status and are overall healthy — then they can safely and effectively receive HD IL-2 regardless of whether they have favorable, intermediate, or even poor prognosis per IMDC. That’s important to know.”

Patients in all risk groups saw median and 2-year survival rates “consistent with recent reports of checkpoint or targeted therapies for mRCC,” the authors noted.1

Registry analyses are difficult to interpret or to compare with other studies because of patient selection bias, Dr Hurwitz cautioned.

The FDA approved HD IL-2 for mRCC in 1992. “It was one of the earliest efficient treatment strategies for RCC, for the most common histology, clear-cell RCC, which represents approximately 75% of all kidney cancers,” Dr Msaouel said. “We have decades of experience with HD IL-2, and that means we have been monitoring its efficacy longer than is the case with newer treatment regimens.”