ALK Fusion Oncogenes in Lung Adenocarcinoma

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1 ALK Fusion Oncogenes in Lung Adenocarcinoma Vincent A Miller, MD Associate Attending Physician, Thoracic Oncology Service Memorial Sloan-Kettering Cancer Center New York, New York

2 The identification of EGFR TK domain mutations in lung adenocarcinomas and their profound sensitivity to treatment with small molecule EGFR TKIs has revolutionized how we think about non-small cell lung cancer. Individuals without EGFR or K-ras mutations are now tested for ALK FISH looking for rearrangement of the ALK gene. Dr Kwak and Dr Shaw recently presented data on the promising efficacy of a kinase inhibitor for this fusion protein in patients with non-small cell lung cancer. ALK FISH testing in lung cancer could have important clinical and research implications.

3 ALK Fusion Oncogenes in Lung Adenocarcinoma Translocations resulting in fusion genes A receptor tyrosine kinase (anaplastic lymphoma kinase [ALK]) fuses to the echinoderm microtubule-associated protein-like 4 (EML-4) [Soda Nature 2007] Multiple chimeras found there are other fusion partners besides EML-4 Oncogenic Activation enhances proliferation and survival, changes cell shape through KRAS-ERK, JAK3-STAT, PI3K

4 ALK fusions result from translocations analogous to BCR- ABL in CML. Why they happen and how particular partners are identified is the subject of a lot of research at a very basic level from multiple labs. In lung cancer the chimeric protein involves the anaplastic lymphoma kinase or ALK fused most commonly but not exclusively, to the echinoderm microtubule-associated protein-like 4 or EML4. This was first described two years ago, which is encouraging in that it took us five years to get the EGFR story to prime time but in just two years, we ve gotten enough momentum in the field to have an agent in trial that s working.

5 EML4-ALK Fusion Gene in NSCLC (Non-Small-Cell Lung Cancer) Source: Reprinted by permission from Macmillan Publishers Ltd: Nature 448;561, copyright 2007.

6 Although there are multiple partners for the ALK protein, nearly all the fusion proteins seem to include the ALK kinase domain, so they should be susceptible to kinase inhibition. Activation enhances proliferation/survival through some of the players you ve seen before, things like PI3 kinase, JAK-STAT, and K-ras and ERK. The frequency of this fusion in the initial papers was reported to be about four or five percent in adenocarcinoma, which would require screening of a large number of patients to find one mutation, making timely completion of a clinical trial difficult.

7 ALK Anti-Apoptotic Signaling Occurs via PI3K Source: Reprinted by permission from Macmillan Publishers Ltd: Nat Rev Cancer 8:11-23, copyright 2008.

8 PI3-kinase mediates, in part, growth signals from the ALK protein. Therefore, if a patient had a PI3-kinase mutation or some other dysregulation in that axis, they might be insensitive to effective inhibition of the ALK kinase.

9 Clinical Activity Observed in a Phase 1 Dose-Escalation Trial of an Oral MET and ALK Inhibitor PF Source: Kwak EL et al. Proc ASCO 2009;Abstract 3509.

10 These are results of the trial that Dr Eunice Kwak presented at ASCO and which were updated at this IASLC meeting by Dr Shaw, of the Pfizer drug, I should point out that this drug is an inhibitor both of MET and ALK, which is not necessarily characteristic of all agents in that class.

11 RP2D Molecular Cohort: NSCLC with ALK Fusion (n = 19) Source: With permission from Kwak EL et al. ASCO Abstract 3509.

12 This trial began with accrual of patients with different types of malignancies, and then, based on early response in a patient with an inflammatory myofibroblastic tumor, it was expanded to include a cohort of lung cancer patients with this ALK fusion. Like patients whose tumors have EGFR mutations, patients with ALK fusions also seem to have unique clinical characteristics. These patients tend to be former or never-smokers and to have adenocarcinoma. Notably, many of these patients were heavily pretreated.

13 EML-4 ALK Fusion Oncogene in Lung Adenocarcinoma: Clinical and Pathologic Characteristics Patients may be younger and are more commonly male More common in adenocarcinoma and never or modest smokers Unlike EGFR mutation may NOT be prognostic Like EGFR mutation largely exclusive from KRAS mutation Rare to occur with EGFR mutation Occurs in 25% of EGFR/KRAS WT never smokers Source: Shaw AT et al. J Clin Oncol 2009;27(26):

14 Unlike EGFR mutations, early data suggests these ALK fusion mutations may not be prognostic. Like EGFR mutations, these appear essentially to be exclusive from K-ras mutations. There have been one or two cases reported where individuals also have an EGFR mutation. One of the ways we think we can enrich for detecting this abnormality is to test the subgroup of patients who are EGFR and K-ras nonmutated and never-smokers. The incidence there as you saw at this meeting and as previously reported by Dr Shaw s group can be as high as 25 percent in that population.

15 Tumor Responses to PF for NSCLC Evaluable Patients with ALK Fusions Source: With permission from Kwak EL et al. ASCO Abstract 3509.

16 This is the waterfall plot presented at ASCO and then subsequently updated with about 10 more patients at this meeting, showing a curve very reminiscent of what we saw with EGFR tyrosine kinase inhibitors in patients with EGFR tyrosine kinase domain mutations. Very impressive responses, although it is noted that a number of these responses are early on, so we don t have data yet on their durability.

17 Molecular Cohort: NSCLC ALK Fusion Overall response rate = 53% (10/19 pts) Disease control rate at 8 weeks = 79% (15/19 pts) 4 patients had progression at first evaluation Sources: Kwak EL et al. ASCO Abstract 3509; Shaw AT et al. J Clin Oncol 2009;27:4247

18 The overall response rate at the time of the ASCO presentation was 53 percent, and four patients had progression at first evaluation. Again, it will be important to try to characterize what coexistent genetic events prevent those individuals from responding.

19 48 yo Female Non-Smoker with NSCLC ALK Fusion Source: With permission from Kwak EL et al. ASCO Abstract 3509.

20 These scans of a patient in the study were shown at the ASCO presentation by Dr Kwak.

21 ALK-Related Efficacy Evaluable Patients w/ NSCLC Source: With permission from Kwak EL et al. ASCO Abstract 3509.

22 These are some of the pretreatment characteristics of individuals on this study and their duration on the ALK inhibitor on the far right.

23 ALK Fusions: A Therapeutic Target in NSCLC ALK tyrosine kinase druggable Phase II and III trials of PF in patients with ALK fusions are imminent Testing now available commercially and at certain institutions

24 This is a druggable target. Phase II and Phase III trials of the agent, , in patients with ALK rearrangement are imminent. Comparison of multiple platforms for screening and diagnosis are ongoing.

25 Conclusions Non-small cell lung cancer is no longer one disease treated empirically with one or two chemotherapy regimens. NSCLC, and in particular adenocarcinoma, must be subtyped both pathologically and genotypically. EGFR mutations served as a watershed event for this fundamental paradigm change, but other druggable kinase mutations will continue to be identified.

26 I would like to conclude by emphasizing again that lung adenocarcinoma is now not one disease. It s probably moved on to four or five diseases, and it may well be like lymphoma or perhaps broader than that in the coming decades. I believe that non-small cell lung cancer, and particularly the adenocarcinomas, must be subtyped both pathologically and genotypically. EGFR mutations are not the end of the story they re the beginning of the story. They re a watershed event and have led to a fundamental paradigm change. I think other druggable kinase mutations will continue to be identified, but, again, that, in turn, is not the final solution to our problems, as an identifiable kinase mutation is probably present in only about half of advanced lung adenocarcinomas.