Model Emerges for Targeting Oncogenes in NSCLC
Published Online: Monday, December 30, 2013
Alice T. Shaw, MD, PhD
That less than five years had elapsed between discovery of a newly defined subtype of NSCLC and the development, testing, and FDA approval of an effective targeted therapy (along with a diagnostic test) may serve as a model for successful next-generation development of targeted therapies, according to Alice T. Shaw, MD, PhD, from Harvard Medical School and Massachusetts General Hospital, in Boston. Shaw traced events that mark this example of contemporary bench-to-bedside science at the 11th International Congress on Targeted Therapies in Cancer that Physicians’ Education Resource, LLC (PER®) hosted in Washington, DC, in August.
ALK rearrangements were first discovered in anaplastic large cell lymphoma about 20 years ago, and “rediscovered” in 2007 by Hiroyuki Mano, MD, PhD, and colleagues from Japan. Mano led a research team that found a fusion gene with portions of the echinoderm microtubule-associated protein-like 4 (EML4) gene and ALK in a small subset of Japanese patients with NSCLC.2 The EML4-ALK fusion activates ALK, which is normally not expressed in the lung.
Mano’s research also found that, not only was the EML4-ALK fusion gene a potent oncogenic driver in nude mice models, but blocking the kinase activity of EML4-ALK “completely abrogated” the oncogenic activity.2 Gene translocations that activate tyrosine kinases may represent excellent drug targets for many cancers, especially with NSCLC, according to Shaw.
ALK rearrangements occur in 3% to 7% of patients with NSCLC who share a few key characteristics. Specifically, ALK rearrangements are enriched in patients who are never- or light smokers and tend to be found in patients who are 10 to 15 years younger than the average patient with NSCLC. They occur primarily in the adenocarcinoma type of NSCLC.3,4
When the expansion phase of the phase I clinical study of crizotinib commenced—at approximately the same time as the ALK-rearranged NSCLC subtype was identified—early results showed that the majority of patients had responded.5,6 In the phase II follow-up, single-arm study in patients with advanced ALK-positive lung cancer, the drug produced a similarly high response rate of about 60%. In both studies, median progression-free survival (PFS) was about 8 to 10 months. Crizotinib approval was based on the response rate seen in these trials.1
The role of crizotinib in the treatment of ALK-positive lung cancer was confirmed by a head-to-head comparison of crizotinib to standard chemotherapy in patients with advanced ALK-positive lung cancer.7 In this phase III trial, all patients were ALK-positive by the standard fluorescence in situ hybridization (FISH) assay, and all had failed first-line platinum-based chemotherapy. The primary endpoint was PFS. Secondary endpoints were response rate, overall survival, safety, and patient-reported outcomes.7
Patients were randomized 1:1 to receive either crizotinib or a standard second-line agent, such as pemetrexed or docetaxel. No crossover was designed. However, once patients progressed on the chemotherapy arm, they came off study and received crizotinib in a separate ongoing phase II study, according to Shaw.7
The study met its primary endpoint of PFS. Median PFS with crizotinib was nearly 8 months (7.7 months) versus 3 months with standard chemotherapy with a hazard ratio [HR] of 0.49 and a highly statistically significant P value.7 At over 60%, the response rate with crizotinib was consistent with data that had previously been seen in the phase I and II studies. Reponses with chemotherapy were low, at about 20%.7
Especially encouraging in this phase III trial were responses to a patient-reported outcomes instrument.7 “Patients who received crizotinib experienced significantly improved disease-related symptoms and also reported improved quality of life relative to baseline, compared to those patients who had received chemotherapy,” Shaw said.
That study is currently being followed by another randomized study of crizotinib versus first-line platinum plus pemetrexed.8 Additional data on crizotinib in the first-line setting may be available within the next year.
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