The American Society of Clinical Oncology (ASCO) Value Framework determines the long-term benefit of immune checkpoint inhibitors (ICIs) using milestone survival at twice the control median survival and uses that measure to award tail-of-the-curve bonus points.
Authors of a recent study proposed an alternative approach: using late-life expectancy, defined as “the area under the Kaplan–Meier curve from median survival time in the control arm to the end of follow-up,” to assess the benefits of ICIs. The study details were published online January 4, 2019, in the Journal of the National Cancer Institute.
The authors asserted that the approach used by the ASCO Value Framework has drawbacks, including milestones reflecting only a single point on a survival curve. This milestone is not always achieved, they pointed out.
Researchers examined all of the ICIs approved by the US Food and Drug Administration (FDA) from 2011 to 2018 and their indications (6 ICIs representing 27 indications), and selected those that included survival data. There were 13 indications that fit this description. Of these 13 indications, the study authors found that only 69.2% (9 of 13) met the criteria for bonus points awarded by the ASCO Value Framework.
The study authors proposed a scoring frame based on the ratios of late-life expectancies as an alternative to ASCO’s model. ICIs with a ratio of late-life expectancies of more than 1.5 are allocated 20 points for overall survival and 16 points for progression-free survival; a ratio of less than or equal to 1 earned an ICI zero points, while a ratio between 1 and 1.5 earned an ICI a bonus proportional to the ratio.
“Our proposed score recognized a long-term benefit not captured by the ASCO-VF [Value Framework], for example, for CHECKMATE-66 where twice the median overall survival was not reached,” the study authors wrote. Using the study authors’ proposed scoring frame, the ICI in CHECKMATE-66 had a late-life expectancy ratio of 1.65, earning it a score of 20 points. This score better highlighted the “important long-term benefit of nivolumab,” they reasoned.
“In conclusion, the ASCO-VF could be improved with the use of late-life expectancy,” the study authors wrote.
- Vivot A, Créquit P, and Porcher R. Use of late-life expectancy for assessing the long-term benefit of immune checkpoint inhibitors [published online January 4, 2019]. J Natl Cancer Inst. doi: 10.1093/jnci/djy211