Pfizer, Inc., just months after launching Xalkori (crizotinib) for the treatment of non-small cell lung cancer with a companion diagnostic developed by Abbott Laboratories’ Abbott Molecular Diagnostics, is looking to develop a second diagnostic test for the drug, this time with a different partner, Roche’s Ventana Medical Systems, Inc. The two companies announced a partnership Jan. 10 to develop a companion diagnostic test to identify patients with anaplastic lymphoma receptor tyrosine kinase (ALK) gene rearrangements who are most likely to benefit from treatment with Xalkori.

Through the partnership with Ventana, Pfizer is looking to develop the first fully automated and standardized immunohistochemistry companion (IHC) diagnostic test for ALK mutations. Though the test targets the same ALK mutation, it is different from the one developed by Abbott Molecular, the Vysis ALK Break Apart FISH Probe Kit. Abbott’s fluorescence in situ hybridization (FISH) test and Pfizer’s Xalkori were approved simultaneously by FDA in August Also see "Pfizer’s Crizotinib Eases Past FDA With Targeted Population" - Pink Sheet, 29 August, 2011..

The ALK gene mutation is found in less than 5% of NSCLC patients, so identifying the appropriate patients who can benefit early in the course of treatment is critical to Xalkori’s commercial success. Lung cancer patients are not always tested for gene mutations, largely because targeted treatments only recently have become available and because full biopsies, in which the highest quality and largest tissue samples are collected, aren’t usually conducted because of the invasiveness of the procedure Also see "NSCLC Market Snapshot: Promising Biomarkers, Testing Challenges" - Pink Sheet, 30 May, 2011.. Demand for testing is on the rise, however, as more mutations are identified and targeted treatments become available.

IHC Test Is A Cost Effective Alternative

IHC and FISH are two tests frequently used in oncology to identify a range of biomarkers. FISH, a nucleic-acid-based assay that measures DNA, is generally considered more accurate than IHC, which is a protein-based test. However, FISH testing is expensive and not as widely available. The IHC test is typically less expensive to run, and since Ventana’s instrumentation is widely used around the world, it can be easily automated.

In the arrangement with Pfizer, Ventana will develop the test, which will measure the associated protein product that is found when an ALK gene rearrangement is present. The test will be based on antibody developer Cell Signaling Technology Inc.’s D5F3 antibody and Ventana’s Optiview DAB detection for performance on Ventana’s automated platforms.

How the testing paradigm will play out between FISH and IHC in lung cancer remains to be seen. “One thing we do know is that it will be an additional option,” said Jay Foust, senior director, head of strategic marketing, Ventana Translational Diagnostics.

Labeling for Xalkori stipulates it is approved for patients who test positive for the ALK mutation on an FDA approved test. Thus, payors can require prior authorization based on the requirement that patients test positive for the ALK mutation. Pfizer is looking to expand the use of Xalkori to other tumors types that are also associated with the ALK mutation; having multiple testing options in hand could help facilitate increased use of the drug.

Pfizer Turns To Ventana To Expand Companion Dx Options For Xalkori

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