Patient Description

Ms K, a 67-year-old white female and never-smoker, presented with dyspnea on exertion and vague right upper quadrant pain. Physical examination disclosed a 2-cm right supraclavicular node (SCN) and diminished breath sounds in the right lung. Chest X-ray demonstrated a 3-cm mass in the right upper lobe and a right pleural effusion. Computed tomography (CT) confirmed the presence of a 3.2-cm right upper lobe mass with multiple ipsilateral and contralateral pulmonary nodules and a moderate-size right pleural effusion, and at least ten space-occupying lesions in the liver ranging in size from 10 to 20 mm. Mediastinal windows confirmed right hilar and paratracheal nodes and right SCN. Magnetic resonance imaging (MRI) of the brain proved negative.

The patient underwent right SCN biopsy, which revealed adenocarcinoma positive for thyroid transcription factor-1 (TTF-1). Tissue was sent for KRAS and epidermal growth factor receptor (EGFR) gene mutation testing, and both returned negative or "wild type."

A decision was made to start combination bevacizumab with paclitaxel and carboplatin. The patient had a profound partial response with resolution of the pleural effusion, right SCN, and pulmonary nodules and 50% shrinkage of the primary lesion, hilar and mediastinal nodes, and liver metastases. After six cycles, she went onto maintenance therapy with bevacizumab alone. Unfortunately, after four cycles of maintenance bevacizumab, dyspnea on exertion and cough recurred. Follow-up CT demonstrated growth of the primary tumor and reappearance of pulmonary nodules. In addition, the liver metastases had doubled in size.

Clinical Decision Point 1a: EML4-ALK Mutation Testing

Question 1a: Should this patient be evaluated for the EML4-ALK fusion oncogene?

1. Yes
2. No

Discussion
(a) Approximately 5% of patients diagnosed with advanced non-small-cell lung cancer (NSCLC), or more than 70,000 individuals annually worldwide, harbor the fusion oncogene made up of portions of the echinoderm microtubule-associated protein-like 4 (EML4) gene and the anaplastic lymphoma kinase (ALK) gene.¹ The significance of the EML4-ALK fusion oncogene is that emerging ALK inhibitors have shown clinical efficacy in patients with NSCLC who have this oncogene.¹ The relative likelihood of EML4-ALK is far higher in never-smokers or former light smokers (≤10 pack years and quit ≥1 year ago) and in those with adenocarcinoma of the lung.¹ It is also higher in individuals with wild type EGFR and KRAS, because according to current data, EGFR or KRAS mutations and EML4-ALK appear to be mutually exclusive.^2,3 The chance, therefore, of having EML4-ALK is even higher in patients with the candidate phenotype who are wild type for EGFR and KRAS. Given the patient's phenotype and EGFR status, it is appropriate to test her for the EML4-ALK.

Soda et al first reported the EML4-ALK fusion oncogene in 2007 after discovering it in a lung adenocarcinoma specimen surgically resected from a 62-year-old man with a history of smoking.⁴ EML4-ALK results from an alteration on the short arm of chromosome 2 at the point of 2p21-p23 (Figure 1).^5,6 Although first described by Soda as an inversion,⁴ more complex cytogenetic alterations, including amplification, have since been identified.⁵ While multiple breakpoints in different EML4 exons may occur, all variants preserve the intracellular tyrosine kinase domain of ALK and the coiled-coil domain of EML4.¹ Other ALK fusion partners exist in NSCLC, including TFG and KIF5B.¹ Mutations involving ALK are oncogenic due to the transforming activity, usually by dimerization, of the fusion partner on ALK's tyrosine kinase activity, leading to increased cell proliferation.^1,7

Audio Commentary by Dr. Herbst

Figure 1. Chromosome 2 and EML4-ALK^5,6

ALK inhibitors target the aberrant ALK tyrosine kinase and its proliferative activity in much the same way that erlotinib and gefitinib target the tyrosine kinase activity of EGFR in NSCLC patients with EGFR mutations. A recent two-part phase I trial studied the ALK inhibitor PF02341066, or crizotinib.^8,9 Crizotinib is an oral drug belonging to the new class of c-met/hepatocyte growth factor receptor (HGFR) tyrosine kinase inhibitors¹⁰ with dual inhibition of ALK and MET tyrosine kinases.¹¹ Part one of the phase I trial was a dose-escalation study that evaluated crizotinib, 50 mg once daily to 300 mg twice daily, in patients with a variety of advanced and refractory solid tumors, including NSCLC.^8,9 The maximum tolerated dose was established at 250 mg twice daily due to dose-limiting fatigue in the cohort receiving 300 mg twice daily.⁹ Part two of the phase I trial continued the evaluation of crizotinib (250 mg BID only) in an expansion cohort, enrolling 82 patients with advanced, largely "refractory" NSCLC who were positive for the EML4-ALK fusion oncogene.⁹ Data available as of April 7, 2010 were published in the October 28 issue of The New England Journal of Medicine. These data showed that 47 of 82 patients (57%) achieved a response, including 46 partial responses and 1 complete response, after a mean treatment duration of 6.4 months with follow-up ongoing. Although progression-free survival was not an end point of this study and median progression-free survival was not reached at 6 months as of the data cut-off date, the probability of 6-month progression-free survival was estimated at 72%. The most common adverse events were grade 1 gastrointestinal events and visual disturbances. Mild to moderate increases in liver transaminases were also observed.

Updated results from the expansion cohort—with a total of 113 patients in the database and data available as of August 7, 2010—were reported at the 35th Congress of the European Society for Medical Oncology (ESMO) in Milan, Italy in October 2010.¹² An objective response (complete or partial) was achieved by 56.2% of patients with a median duration of response of 36.3 weeks. Figure 2 shows the tumor response by patient. The median progression-free survival was 9.2 months, with a median duration of follow-up of 8.0 months. A total of 54 patients continue to be followed for progression-free survival.

Figure 2. Tumor Response by Patient (Best Percent Change in Tumor Size)¹²

With permission from Dr. D. Camidge.

Clinical Decision Point 1b: Method of EML4-ALK Mutations Testing

Question 1b: By what method would you test for the EML4-ALK fusion oncogene?

1. Work-up the original SCN node biopsy
2. Perform fiberoptic bronchoscopy with endobronchial ultrasound-guided fine needle aspiration
3. Perform a liver biopsy

Discussion
(a) It would be most convenient for the patient to have the original biopsy evaluated for the EML4-ALK translocation. This approach also avoids the morbidity of a repeat biopsy. If the tissue were depleted or unavailable, then a core biopsy would be necessary. Liver biopsy would be more likely to provide adequate material. Is it important to note that testing for EML4-ALK in potential clinical trial candidates mandates tissue, ie, formalin-fixed, paraffin-embedded (FFPE) tumor samples, not merely cytology.⁹

Currently, there is no standard method for detecting EML4-ALK in lung tissue, although a number of diagnostic techniques are available.¹ Reverse-transcriptase (RT)-PCR is an extremely sensitive method, but has some procedural technical challenges, including the potential for false positives.¹ Importantly, RT-PCR is more difficult to perform on FFPE tissues, compared with fresh tissues, due to the high degradation of extracted RNA.¹

Fluorescence in situ hybridization (FISH) can also be used to identify EML4-ALK.¹ A split signal using the appropriate probe suggests the presence of any inter-chromosomal or intra-chromosomal ALK mutation, including those not involving EML4.¹ False negatives are possible with this method, however, due to the subtle split signal often associated with EML4-ALK mutations.¹ Additionally, tissue morphology may be disrupted when FFPE tissue is used.¹ FISH was the detection method used in phase I crizotinib testing.⁹ Samples were considered positive for an ALK rearrangement if more than 15% of scored tumor cells had split signals.⁹ Whether EML4 was the specific fusion partner was confirmed by RT-PCR.⁹

Immunohistochemistry (IHC) analysis has the advantage of maintaining tissue morphology and is a methodology common to pathology laboratories.¹ Its application to the detection of ALK mutations in NSCLC is not clinically practical, however, due to the low level of ALK expression and the potential for weak staining.¹

Audio Commentary by Dr. Herbst

Case Continues
Work-up of the patient's original SCN specimen proved positive for EML4-ALK. Enrollment in a clinical trial was discussed with the patient. Two separate trials of crizotinib are currently recruiting patients with EML4-ALK. The phase III trial (PROFILE 1007) is an open-label trial enrolling patients who have had exposure to one prior platinum-containing chemotherapy regimen, randomizing them to either crizotinib or standard chemotherapy (docetaxel or pemetrexed).¹³ A separate phase II open-label trial (PROFILE 1005) is evaluating single-agent crizotinib in patients who have received two or more prior systemic regimens.¹⁴

The patient was enrolled in PROFILE 1007 and was randomized to oral crizotinib 250 mg BID on a continuous schedule. After 6 months, she achieved 90% tumor regression.

Audio Commentary by Dr. Herbst

Clinical Decision Point 2: Treatment Duration

Question 2: How long should you treat this patient with crizotinib?

1. For 1 year, then observe
2. For 6 months due to the potential risk of resistance
3. Until disease progression or intolerable adverse events

Discussion
(c) In the absence of disease progression or toxicity, there is no empiric reason to stop therapy. To date, there have been no reports of cumulative toxicity or late, dangerous complications, associated with crizotinib. In phase I testing, therapy with crizotinib continued until patients progressed or developed intolerable adverse events.⁹ As of April 7, 2010, 19 patients had discontinued treatment for the following reasons: disease progression, 13; crizotinib-related adverse event, 1 (recurrence of grade 3 ALT despite dose reduction); nondrug-related adverse events, 1; death from unrelated causes, 2; and, other, 2.⁹ Among the initial 82 patients with NSCLC, 63 patients (77%) continued to receive crizotinib after the study's data cutoff.⁹ Twelve patients received therapy for at least 40 weeks, 8 for at least 50 weeks, 3 for at least 70 weeks, and 1 for more than 80 weeks.⁹ As of August 7, 2010, a total of 36 patients out of 113 had discontinued treatment: disease progression, 23; drug-related adverse events, 1; non-drug-related adverse events, 2; death, 7; withdrawal of consent, 1; and other, 2.¹²

Audio Commentary by Dr. Herbst

One case report has been published about ALK resistance mutations with crizotinib use.¹⁵ The patient was in the expansion cohort of the phase I trial. After 5 months of treatment, during which time the subject achieved a partial response, disease progression developed. Molecular analysis detected two distinct acquired mutations, which conferred resistance to multiple ALK inhibitors.

Although resistance may develop over time with any targeted therapy, any future potential risk of resistance is not a reason to truncate therapy that is producing good response in a patient. The development of resistance will be manifest in disease progression. If and when that occurs, the patient should be evaluated for ALK resistance mutations. If present, the patient may then be considered for a study targeting patients who have developed clinical resistance.

Audio Commentary by Dr. Herbst

Case Continues
The patient remained free of progression for more than 1 year before her cancer again progressed. Although her chest disease remained responsive, her liver metastases began to grow. She underwent re-biopsy and proved to have an ALK resistance mutation.

Clinical Decision Point 3: Third-Line Therapy

Question 3: Which of the following options should be ruled out at this point?

1. Enroll patient in a phase I clinical trial aimed at overcoming ALK inhibitor resistance
2. Initiate pemetrexed
3. Initiate erlotinib or gefitinib

Discussion
(c) For this patient, erlotinib and gefitinib should be ruled out as the next step, although this approach could be entertained later if all other strategies failed. As is typical of patients with EML4-ALK translocation, this patient does not have an EGFR mutation, and therefore, would likely be insensitive to an EGFR tyrosine kinase inhibitor such as erlotinib or gefitinib.³ Better options include initiating pemetrexed or enrolling the patient in a clinical trial.

Pemetrexed would be the standard approach in this situation. It is FDA approved for the treatment of patients with locally advanced or metastatic nonsquamous NSCLC after prior chemotherapy.¹⁶ With therapeutic equivalence to docetaxel in this setting, pemetrexed is considerably less toxic.¹⁷ In addition, pemetrexed may have a preferential advantage in patients with adenocarcinoma compared with docetaxel.¹⁸

If the patient is reasonably asymptomatic and motivated, it would be appropriate to proceed with a phase I clinical trial geared toward overcoming ALK inhibitor resistance. A number of emerging kinase inhibitors are in development that may have the potential to overcome crizotinib-related ALK resistance mutations either by increased potency or by efficacy against the mutations.¹⁹ Phase I trials of AKT kinase inhibitor GSK-2141795 as monotherapy²⁰ or in combination with mitogen-activated protein kinase inhibitor GSK1120212 are currently recruiting.²¹ (AKT is a downstream signaling target of activated ALK.²²) ALK kinase inhibitors in preclinical development include CEP-28122 and AP-26113, with investigational new-drug applications expected soon, and X-276.¹⁹

Audio Commentary by Dr. Herbst

Case Continues
Because of logistical issues precluding out-of-town travel for a clinical trial evaluating therapies to overcome ALK inhibitor resistance, the patient opted for standard chemotherapy. (It is important to note that in general, patients positive for EML4-ALK are often sensitive to chemotherapy.³) She went on to receive pemetrexed 500 mg/m² IV every 3 weeks with folic acid and vitamin B12 support and has had a 20% tumor regression to date after three cycles.

Conclusion

First reported in 2007, EML4-ALK has become an important new target for approximately 5% of patients with NSCLC. Those who harbor this fusion oncogene appear to be extraordinarily sensitive to crizotinib, a first-in-class ALK inhibitor. This breakthrough has opened up therapeutic options that did not previously exist, but crizotinib is not a panacea or cure. Responses are often profound, but progression is likely to be inevitable in the vast majority of patients. Strategies to overcome or mitigate resistance are essential, but still fledgling. Patients with the EML4-ALK fusion oncogene may still be sensitive to conventional cytotoxics. Clinical testing of crizotinib is ongoing to fully determine efficacy and safety, and other emerging kinase inhibitors, active against EML4-ALK, are also in development.

References

1. Sasaki T, Rodig SJ, Chirieac LR, Jänne PA. The biology and treatment of EML4-ALK non-small cell lung cancer. Eur J Cancer. 2010;46:1773-1780.


2. Inamura K, Takeuchi K, Togashi Y, et al. EML4-ALK fusion is linked to histological characteristics in a subset of lung cancers. J Thorac Oncol. 2008;3:13-17.


3. Shaw AT, Yeap BY, Mino-Kenudson M, et al. Clinical features and outcome of patients with non-small-cell lung cancer who harbor EML4-ALK. J Clin Oncol. 2009;27:4247-4253.


4. Soda M, Choi YL, Enomoto M, et al. Identification of the transforming EML4-ALK fusion gene in non-small-cell lung cancer. Nature. 2007;448:561-566.


5. Perner S, Wagner PL, Demichelis F, et al. EML4-ALK fusion lung cancer: a rare acquired event. Neoplasia. 2008;10:298-302.


6. National Institute of Diabetes and Digestive and Kidney Diseases. Hembase Search. Chromosome 2. Available at: http://fmp-8.cit.nih.gov/hembase/chr.php?chr=2. Accessed on: November 19, 2010.


7. Chiarle R, Voena C, Ambrogio C, Piva R, Inghirami G. The anaplastic lymphoma kinase in the pathogenesis of cancer. Nat Rev Cancer. 2008;8:11-23.


8. ClinicalTrials.gov. A study of oral PF-02341066, a c-Met/hepatocyte growth factor tyrosine kinase inhibitor, in patients with advanced cancer. Available at: http://clinicaltrials.gov/ct2/show/NCT00585195. Accessed on: November 23, 2010.


9. Kwak EL, Bang YJ, Camidge DR, et al. Anaplastic lymphoma kinase inhibition in non-small-cell lung cancer. N Engl J Med. 2010;363:1693-1703.


10. National Cancer Institute. Dictionary: crizotinib. Available at: http://www.cancer.gov/drugdictionary/?CdrID=586080. Accessed on: December 2, 2010.


11. Christensen JG, Zou HY, Arango ME, et al. Cytoreductive antitumor activity of PF-2341066, a novel inhibitor of anaplastic lymphoma kinase and c-Met, in experimental models of anaplastic large-cell lymphoma. Mol Cancer Ther. 2007;6(12 Pt 1):3314-3322.


12. Camidge DR, Bang Y-J, Iafrate AJ, et al. Clinical activity of crizotinib (PF-02341066), in ALK-positive patients with non-small cell lung cancer (NSCLC). Abstract 366PD. Presented at: 35th Congress of the European Society for Medical Oncology; Milan, Italy; October 8-12, 2010.


13. ClinicalTrials.gov. An investigational drug, PF-02341066 is being studied versus standard of care in patients with advanced non-small cell lung cancer with a specific gene profile involving the anapestic lymphoma kinase (ALK) gene. Available at: http://clinicaltrials.gov/ct2/show/NCT00932893. Accessed on: November 22, 2010.


14. ClinicalTrials.gov. An investigational drug, PF-02341066, is being studied in patients with advanced non-small cell lung cancer with a specific gene profile involving the anapestic lymphoma kinase (ALK) gene. Available at: http://clinicaltrials.gov/ct2/show/NCT00932451. Accessed on: November 22, 2010.


15. Choi YL, Soda M, Yamashita Y, et al. EML4-ALK mutations in lung cancer that confer resistance to ALK inhibitors. N Engl J Med. 2010;363:1734-1739.


16. Alimta® [package insert]. Indianapolis, IN: Eli Lilly and Company; 2010.


17. Hanna N, Shepherd FA, Fossella FV, et al. Randomized phase III trial of pemetrexed versus docetaxel in patients with non-small-cell lung cancer previously treated with chemotherapy. J Clin Oncol. 2004;22:1589-1597.


18. Peterson P, Park K, Fossella F, et al. Is pemetrexed more effective in adenocarcinoma and large cell lung cancer than in squamous cell carcinoma? A retrospective analysis of a phase III trial of pemetrexed versus docetaxel in previously treated patients with advanced non-small cell lung cancer. J Thorac Oncol. 2007;2(suppl 4):S851.


19. Garber K. ALK, lung cancer, and personalized therapy: portent of the future? J Natl Cancer Inst. 2010;102:672-675.


20. ClinicalTrials.gov. A Phase I, Open-Label, First-Time-In-Human Study of the Oral AKT Inhibitor GSK2141795. Available at: http://www.clinicaltrials.gov/ct2/show/NCT00920257. Accessed on: December 2, 2010.


21. ClinicalTrials.gov. Safety, PK of AKT and MEK Combination. Available at: http://www.clinicaltrials.gov/ct2/show/NCT01138085. Accessed on: December 2, 2010.


22. Mossé YP, Wood A, Maris JM. Inhibition of ALK signaling for cancer therapy. Clin Cancer Res. 2009;15:5609-5614.


23. US Food and Drug Administration. Access to investigational drugs outside of a clinical trial (expanded access). June 30, 2010. Available at: http://www.fda.gov/ForConsumers/ ByAudience/ForPatientAdvocates/AccesstoInvestigationalDrugs/ucm176098.htm. Accessed: December 20, 2010.