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K. Syrigos
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PC 02 - Pro vs Con: Is There a Role for EGFR TKIs in EGFR Mutation Negative Disease? / Pro vs Con: Whole Exome Sequencing vs. Selected Testing (e.g., ALK and EGFR) (ID 48)
- Event: WCLC 2015
- Type: Pro Con
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 4
- Moderators:S. Thongprasert, Y. Wu, P. Meldgaard, K. Syrigos
- Coordinates: 9/08/2015, 14:15 - 15:45, 205+207
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PC02.01 - Is There a Role for EGFR TKIs in EGFR Mutation Negative Disease? - Pro (ID 2030)
14:20 - 14:40 | Author(s): S.A. Laurie
- Abstract
- Presentation
Abstract:
With the dramatic clinical benefit that can be observed using tyrosine kinase inhibitors (TKIs) of the epidermal growth factor receptor (EGFR) in patients with non-small cell lung cancer (NSCLC) harbouring activating mutations in EGFR, there has understandably been a focus on the use of these agents in this subset of NSCLC. However, EGFR mutation positive NSCLC represents only approximately 10 – 15 % of all non-squamous NSCLC in non-East Asian patients, and a substantial proportion of East Asian patients do not harbour this mutation. Thus, world-wide, the vast majority of those with NSCLC are so-called “wild-type” for EGFR. For these patients, it is clear from randomized clinical trials that the treatment of choice in the first-line metastatic setting is platinum-doublet chemotherapy. Increasing data suggest that chemotherapy may be preferred in the second-line setting. Is there any role for the use of EGFR TKIs in the wild-type population? Randomized data in which an EGFR TKI is compared to placebo in both the maintenance and refractory settings suggest that there may be. NCIC Clinical Trials Group study BR21 [1] which randomized 731 unselected patients to either erlotinib or matching placebo, was designed and conducted prior to the discovery of activating mutations. Patients had received 1 (50 %) or > 2 (50 %) lines of prior therapy; > 90 % had received a platinum-doublet. An improvement in median survival (6.7 versus 4.7 months [HR 0.70, p < 0.001]) was also associated with a quality of life benefit. This benefit was consistent across subgroups, including in the 50 % of patients with non-adenocarcinoma histology. In a separate analysis of ever-smokers with squamous histology, patients highly unlikely to harbour an EGFR mutation, the magnitude of survival benefit was the same as in the overall study population (median 5.6 versus 3.5 months [HR 0.66, p=0.009])[2]. The SATURN trial [3] randomized 889 patients who had not progressed after 4 cycles of platinum-doublet chemotherapy to either erlotinib or placebo. While of debatable clinical relevance, there was a statistically significant one month prolongation of median survival with the use of erlotinib (HR 0.81, p=0.009). A similar effect was observed in the 44 % of patients with known EGFR wild-type status (HR 0.77, p=0.02). In a pre-planned subgroup analysis [4], a greater magnitude of benefit was observed in those patients whose best response to induction chemotherapy was stable disease (median overall survival 11.9 versus 9.6 months [HR 0.72, p=0.002]), with a similar effect noted in those patients with squamous histology (HR 0.67, p=0.01), and those known to be EGFR wild-type (HR 0.65, p=0.004). Maintenance erlotinib has been shown to not negatively impact quality of life [5], and when used in those with stable disease, to be cost effective [6]. Meta-analyses of placebo-controlled trials of EGFR TKIs in the maintenance setting have confirmed a modest progression-free survival benefit in squamous [7] and known wild-type [8] patients. Multiple trials have compared an EGFR TKI to either docetaxel or pemetrexed in the second-line setting. The TAILOR trial [9], the only trial to prospectively determine and enrol only wild-type patients, showed a clear PFS advantage to docetaxel, and a trend towards improved overall survival. However several other trials that enrolled patients who were unselected with regard to EGFR status had a substantial number of wild type patients, and none of these trials demonstrated a difference in overall survival in wild-type patients between an EGFR TKI and chemotherapy. While these were retrospective analyses on only a subset of enrolled patients with available tissue, wild-type patient numbers in many trials approached (and in one exceeded) the number of patients enrolled to TAILOR. Further, unlike other trials, TAILOR prohibited crossover, which may have impacted survival results, particularly for patients with squamous carcinoma in the erlotinib arm. Taken together these trials suggest that a treatment strategy that includes both chemotherapy and an EGFR TKI sequentially, irrespective of order, will lead to a similar length of survival provided patients receive both lines of therapy. In platinum-pretreated patients who are fit it is likely preferred to use chemotherapy and then at progression move on to an EGFR TKI, as the chance of patients receiving both treatments is higher. Additional data to suggest that EGFR TKIs may have activity in wild-type patients comes from several small, randomized phase II trials comparing second-line chemotherapy with the same chemotherapy with intercalated EGFR TKIs. These studies have shown prolonged PFS in patients treated with the combination. What these trials demonstrate is that EGFR TKIs appear to have a modest treatment effect in EGFR wild-type patients. In these days of targeted therapies leading to substantial treatment effects in a variety of tumours with oncogenic drivers, is this magnitude of benefit sufficient? In lung cancer, many other treatments have been adopted for a similar magnitude of benefit. Although objective response rates to EGFR TKIs are low in wild-type patients, they are also low to standard cytotoxic chemotherapies beyond first-line, and it seems possible that there is a larger proportion of patients with stabilization of disease and / or slowing of progression that is clinically relevant. Not all oncologists or patients will feel that a trial is warranted, but an EGFR TKI is a reasonable choice as last-line therapy when the option is no further treatment, or as maintenance treatment in patients with squamous histology following a best response of stable disease to induction platinum-based chemotherapy. EGFR “wild-type” is a heterogeneous, not homogeneous, population, and as with any therapy, only a subgroup of patients will benefit from treatment. However a consistent reproducible biomarker for benefit in the wild-type subgroup has not yet been discovered. EGFR protein expression, gene copy number, Kras status and serum proteomics have all been evaluated with at times conflicting results, due to limited samples and the retrospective nature of the analyses. The development of rash may be a pharmacodynamic predictor of greater efficacy [10]. Additional work is required to determine which wild-type patients may derive benefit from an EGFR TKI, to avoid needless toxicity and improve cost-effectiveness. References 1. Shepherd et al. N Engl J Med 353: 123-132, 2005 2. Clark et al. Clin Lung Cancer 7:389-394, 2006 3. Cappuzzo et al. Lancet Oncol 11:521-529, 2010 4. Coudert et al. Ann Oncol 23:388-394, 2012 5. Juhasz et al. Eur J Cancer 49:1205-1215, 2013 6. Walleser et al. Clinicoeconomics Outcomes Res 4:269-275, 2012 7. Ameratunga et al. Asia-Pacific J Clin Oncol. 10:273-278, 2014 8. Vale et al. Clin Lung Cancer 16:173-182, 2015 9. Garassino et al. Lancet Oncol 14:981-988, 2013 10. Ding et al. Contemp Clin Trials 29:527-536, 2008
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PC02.02 - Is There a Role for EGFR TKIs in EGFR Mutation Negative Disease? - Con (ID 2031)
14:40 - 15:00 | Author(s): L.V. Sequist
- Abstract
- Presentation
Abstract not provided
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PC02.03 - Whole Exome Sequencing vs. Selected Testing (e.g., ALK and EGFR) - Pro (ID 2032)
15:00 - 15:20 | Author(s): I.I. Wistuba
- Abstract
- Presentation
Abstract not provided
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PC02.04 - Whole Exome Sequencing vs. Selected Testing (e.g., ALK and EGFR) - Con (ID 2033)
15:20 - 15:40 | Author(s): Y. Yatabe
- Abstract
- Presentation
Abstract:
Great advantages of next generation sequencing have been published so far, and many new genetic alterations were found with whole genome sequencing. Targeted sequencing using next generation sequencing technique can analyze FFPE small biopsy specimens, but may be equivalent or less than the current selected testing, such as EGFR and ALK testing. Although the targeted sequencing can actually analyze multiple genes, most diagnostic panels include the genes that are frequently altered in cancer generally, thus practically useful genes are limited in terms of lung cancer, such as EGFR, ALK, ROS1, and RET. In contrast, whole exome sequencing is potentially useful, as it can comprehensively examine mRNA expression on tumor cells. In general, mRNA in clinical samples well represents tumor genetic status even with significant dilution with the normal cells, which are less active in transcription. However, it is difficult to perserve high quality RNA with clinical samples, and it is unclear that the whole exome sequencing is constantly clinically applicable for small biopsy specimens. Furthremore, there are some cases that show discrepant results between DNA and RNA based assays. As EGFR transcript is suppressed in SCLC, EGFR mutation cannot be detected with the exome sequencing in SCLC transformed as a resistant mechanism to EGFR-TKI treatment. On the other hand, current selected testing for EGFR and ALK has been confirmed with clinical trials and are adjusted to clinical demands, e.g., short turnaround time and high sensitivity.
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