An estimated 44% of US patients with cancer may be eligible for immune checkpoint inhibitor (ICI) drugs and an estimated 13% may respond to the drugs, a retrospective cross-sectional study found. The findings were reported May 3, 2019, in an article published in JAMA Network Open.1

The analysis included all ICIs in oncology for all indications approved by the US Food and Drug Administration through August 17, 2018. To estimate the percentage of patients eligible for ICI drugs, the number of cancer-specific deaths for an immune checkpoint inhibitor indication was divided by the total number of cancer deaths. To estimate response to the drugs, the number of eligible patients was multiplied by the overall response rate listed on the drug label. 

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The study authors found that in 2011 only 1.54% (95% CI, 1.51%-1.57%) of cancer patients in the United States were eligible for ICI therapy, and that percentage grew to 26.86% (95% CI, 26.75%-26.98%) by 2015 and 43.63% (95% CI, 43.51%-43.75%) by 2018. 

As for the benefit of ICI therapy, 0.14% (95% CI, 0.13%- 0.15%) of cancer patients were estimated to respond in 2011, when ipilimumab was approved for unresectable or metastatic melanoma. The percentage increased in 2015 to 5.86% (95% CI, 5.80%-5.92%) and then 12.46% (95% CI, 12.37%-12.54%) in 2018. 

The estimates for ICIs were higher than those reported for genome-targeted therapies (which reportedly benefit 4.9% of cancer patients) but the numbers for ICIs “remain modest,” the study authors wrote. 

“The observations in this article are sobering and remind us to keep expectations of ICIs realistic,” wrote the authors of a corresponding editorial.2 “As the dust settles and the wave of hysteria ebbs, studies like this lend support to physicians as they attempt to explain to most of their patients with cancer the reason they are not receiving ICIs — because these drugs are not appropriate for them.”

References

  1. Haslam A and Prasad V. Estimation of the percentage of US patients with cancer who are eligible for and respond to checkpoint inhibitor immunotherapy drugs. JAMA Netw Open. 2019;2(5):e192535. doi:10.1001/jamanetworkopen.2019.2535
  2. Catenacci DVT, Hochster H, and Klempner SJ. Keeping checkpoint inhibitors in check. JAMA Netw Open. 2019;2(5):e192546.