Which Outcomes Matter in Solid-state Oncology?

When evaluating surrogate outcomes in Solid-state Oncology, the gold standard for measuring clinical trial success is the use of overall survival (OS). However, given the expense and time delay for patients in getting access to important treatments, both the FDA and the EMA (European Medicines Agency) accept progression-free survival (PFS) and disease-free survival (DFS) as appropriate surrogate outcomes. These trials are cheaper to run and take less time, but we wondered if using either PFS or DFS has an impact on getting a positive recommendation from Health Technology Assessment (HTA) agencies. To have a better understanding, we analyzed 245 reviews for six solid-state oncology conditions that were published between 2005 and 2013 by 10 different Health Technology Assessments (HTA) agencies to determine if using PFS or DFS decreased their likelihood of a positive recommendation.

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Chart

So What's the Outcome?

We discovered that the choice of primary outcome was dependent on the oncology condition, which on its own may not be that surprising. Of the six conditions studied, OS was overwhelmingly used in melanoma and small-cell lung cancer, whereas PFS was frequently used in ovarian cancer, and colorectal cancer used OS, PFS, and DFS at similar rates. What did surprise us was that even though OS is highly regarded and agreed to be a more thorough outcome, for reimbursement there doesn't seem to be any significant consequences for using PFS or DFS. This is an important issue and certainly something that we will be following over time.

There are a few key questions we can think about:

  • How does this break down by HTA agency?
  • Specifically, do certain agencies favor OS while others are fine with PFS/DFS?
  • Is it possible that PFS/DFS are more useful in early stages, while OS is more important for later stages?

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