This is the third CDx test to be approved for EGFR, and it is the second EGFR mutation test for a lung cancer therapeutic released this year (Roche’s COBAS test was released in May as a CDx for erlotinib).
Dako’s IHC test was released in 2004 as a CDx for cetuximab, and the first test measuring EGFR. The 9 year gap in new tests for EGFR might seem surprising, but is likely due at least in part to gefitinib being withdrawn by FDA in 2005 due to lack of efficacy. Studies have since shown that EGFR mutation status can be used to identify populations who will benefit from gefitinib, mutations that had already been used to identify candidates for erlotinib (the other TKI approved for EGFR+ lung cancer). It would be interesting to know how often an LDT is used for EGFR mutation testing and whether that has impacted release of new tests. The label for erlotinib was updated in May of this year to require EGFR mutation by an “FDA-approved test.”
Qiagen’s new PCR test measures the same mutations that confer benefit from gefitinib and erlotinib, yet it is indicated as a CDx for afatinib, Boehringer’s drug that is undergoing Priority Review by FDA, as Qiagen and Boehringer collaborated on the development of the EGFR assay. Despite the fact that FDA requires screening for EGFR mutations in the afitinib labeling, it is interesting to note that of the 7 phase 3 clinical trials for afitinib that are currently sponsored by Boehringer, none include EGFR mutation status in the inclusion criteria.