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N. Murray



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    ED14 - Small Cell Lung Cancer (ID 283)

    • Event: WCLC 2016
    • Type: Education Session
    • Track: SCLC/Neuroendocrine Tumors
    • Presentations: 1
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      ED14.05 - Immunotherapy of Small Cell Lung Cancer (ID 6505)

      14:30 - 15:45  |  Author(s): N. Murray

      • Abstract
      • Presentation
      • Slides

      Abstract:
      Immunotherapy of Small Cell Lung Cancer Nevin Murray MD, British Columbia Cancer Agency, Vancouver, Canada The general principles of cytotoxic chemotherapy for advanced SCLC and NSCLC have many similarities and have advanced minimally over the past two decades.(1) The success of cancer genomics research in changing the care of patients with NSCLC with a driver mutation suitable for targeted treatment has been a powerful incentive to discover such molecular targets in SCLC. Although comparative genomic profiling shows some similarities between SCLC and NSCLC, for SCLC, the abnormalities identified to date are mainly tumor suppressor genes.(2) These loss-of-function alterations do not provide the clear opportunity for rapid clinical translation offered by an activating mutation in a known receptor tyrosine kinase. A considerable number of targeted agents have already been tried in SCLC clinical trials without notable success.(3) In contrast, there is a growing body of evidence for immunotherapy as a promising new treatment for both SCLC and NSCLC. Immunotherapy investigated for SCLC includes interferon, vaccines, antibody-drug conjugates and immune checkpoint inhibitors. Interferon and vaccines have been studied in phase II and III trials without sufficient activity to change practice. Although preliminary, the data emerging from trials of antibody-drug conjugates and immune checkpoint inhibitors has generated more excitement and are the focus for this abstract. Antibody-Drug Conjugates The components of an antibody-drug conjugate include an antibody directed at a defined antigen on cancer cells, a linker, and a cytotoxic agent. This package represents an effective mechanism of targeted drug delivery potentially resulting in decreased toxicity and an improved therapeutic index. Rovalpituzumab teserine targets the Notch pathway with a monoclonal antibody portion directed against the cell surface available Notch ligand delta-like protein 3 (DLL3), which is over-expressed in SCLC tumor-initiating cells but not in normal tissue. Rudin et al.(4) have reported a phase I study including 74 patients with previously treated SCLC. The confirmed response rate in 56 evaluable patients was 16%, but in 26 that showed high DLL3 expression, the response rate was 31%. Response rate was 13% in second-line and 25% in the third-line setting with some durable responses observed. A phase II trial for third-line treatment of patients with DLL3 expressing tumors has begun and if positive will be the first approved agent in this setting. Sacituzumab govitecan is another antibody-drug conjugate of a topoisomerase I inhibitor linked to an antibody to the Trop-2 epithelial antigen.(5) In a phase I/II clinical trial enrolling 33 evaluable SCLC patients with a median of 2.5 previous chemotherapies, the response rate was 24% and the median overall survival was 8.1 months. Dose limiting neutropenia was 34% and grade 3+ diarrhea was seen in 9%. Immune Checkpoint Inhibitors Since immune checkpoint blockade is more active in hyper-mutated tumors, SCLC should be a good candidate disease for this treatment because of a strong association with tobacco carcinogenesis and a high frequency of somatic mutations.(2) The most advanced trial evidence is available for a cytotoxic T-cell antibody (CTLA4) and data for two programmed death (PD-1) immune checkpoint inhibitors is emerging. After a randomized phase II trial of ipilimumab and phased chemotherapy showed a modest improvement in progression-free survival as first-line treatment of advanced SCLC,(6) a large phase III placebo controlled trial was performed in which 1,132 previously untreated patients were randomly assigned to receive either etoposide and platinum for four cycles alone or together with the CTLA-4 antibody ipilimumab.(7) The trial was negative with similar response rates and no difference in the primary end point of overall survival (hazard ratio 0.94; 95% CI 0.81-1.09). Immune checkpoint blockade with PD-1 or dual CTLA-4 and PD-1 inhibition may be a more effective strategy. In a large phase I/II trial including 180 previously treated SCLC patients, Antonia et al.(8) reported a response rate of 13% (7/80) with nivolumab 3 mg/kg and 31% (14/45) in a cohort of nivolumab 1 mg/kg plus ipilimumab 3 mg/kg. The activity of nivolumab alone or combined with ipilimumab was seen regardless of PD-L1 expression and not related to platinum sensitivity or line of therapy. The responses were durable with one-year overall survival of 27% for nivolumab alone and 48% for the combination arm. These results have led to two phase III studies among patients with SCLC evaluating nivolumab, nivolumab/ipilimumab versus placebo in the maintenance setting after first-line therapy and nivolumab versus placebo in the second-line setting. As part of a phase IB multi-cohort study (KEYNOTE-028), pembrolizumab was evaluated among patients with relapsed SCLC with PD-L1 positive tumors.(9) Of the 135 SCLC patients screened, 37 (27%) had PD-L1 positive tumors. The response rate was 29% in 24 evaluable patients. The median duration of response was 29 weeks and durable responses were observed. There is an ongoing phase II study of this agent as maintenance therapy after the completion of standard first-line therapy in extensive stage disease. A phase I trial is evaluating pembrolizumab with conconcurrent chemoradiation. Adverse events associated with checkpoint inhibitors is greater with CTLA-4 combined with the PD-1 antibody combination but were generally manageable. The proportion discontinuing therapy for toxicity was usually less than 10%. The literature contains anecdotes of autoimmune syndromes such as limbic encephalitis.(8) Immune para-neoplastic syndromes are expected in a small proportion of patients with SCLC and an increase in their occurrence with immunotherapy requires close monitoring. However, this concern is currently insufficient to impede further trials with these promising agents. Conclusion Over the past 20 years, almost all phase III trials of systemic therapy for SCLC have failed to improve outcome and advances have been restricted to improved application of radiotherapy. Like squamous carcinomas, the SCLC molecular battlefield is complex and bleak with little opportunity of even temporary respite by identification of mutually exclusive oncogenic drivers that can be treated for patient benefit. Ironically, this hyper-mutated genome and greater neo-antigen expression may enhance the probability of success with immunotherapy. One senses that the likelihood is high for approval of antibody-drug conjugates and immune checkpoint inhibitors for SCLC after the current roster of clinical trials are reported. References 1. Murray N, Lam S. Contrasting Management of Small Cell Lung Cancer and Non-Small Cell Lung Cancer: Emerging Data for Low-Dose Computed Tomography Screening. J Thorac Oncol. 2016 Feb;11(2):139-41. 2. Pietanza MC, Ladanyi M. Bringing the genomic landscape of small-cell lung cancer into focus. Nat Genet. 2012 Oct;44(10):1074-5. 3. Murray N, Noonan K. Can we expect progress of targeted therapy of small cell lung cancer? In: Dingemans A, Reck M, Westeel V, editors. Lung cancer. Sheffield: European Respiratory Society; 2015. p. 234. 4. Rudin CM, Pietanza MC, Bauer TM, Spigel DR, Ready N, Morgensztern D, et al. Safety and efficacy of single-agent rovalpituzumab tesirine (SC16LD6.5), a delta-like protein 3 (DLL3)-targeted antibody-drug conjugate (ADC) in recurrent or refractory small cell lung cancer (SCLC). ASCO Meeting Abstracts. 2016 June 21;34(18_suppl):LBA8505. 5. Starodub A, Camidge DR, Scheff RJ, Thomas SS, Guarino MJ, Masters GA, et al. Trop-2 as a therapeutic target for the antibody-drug conjugate (ADC), sacituzumab govitecan (IMMU-132), in patients (pts) with previously treated metastatic small-cell lung cancer (mSCLC). ASCO Meeting Abstracts. 2016 May 31;34(15_suppl):8559. 6. Reck M, Bondarenko I, Luft A, Serwatowski P, Barlesi F, Chacko R, et al. Ipilimumab in combination with paclitaxel and carboplatin as first-line therapy in extensive-disease-small-cell lung cancer: results from a randomized, double-blind, multicenter phase 2 trial. Ann Oncol. 2013 Jan;24(1):75-83. 7. Reck M, Luft A, Szczesna A, Havel L, Kim SW, Akerley W, et al. Phase III Randomized Trial of Ipilimumab Plus Etoposide and Platinum Versus Placebo Plus Etoposide and Platinum in Extensive-Stage Small-Cell Lung Cancer. J Clin Oncol. 2016 Jul 25. 8. Antonia SJ, Lopez-Martin JA, Bendell J, Ott PA, Taylor M, Eder JP, et al. Nivolumab alone and nivolumab plus ipilimumab in recurrent small-cell lung cancer (CheckMate 032): a multicentre, open-label, phase 1/2 trial. Lancet Oncol. 2016 Jul;17(7):883-95. 9. Ott PA, Callahan MK, Odunsi K, Park AJ, Pan LS, Venhaus RR, et al. A phase I study to evaluate the safety and tolerability of MEDI4736, an anti- programmed cell death-ligand-1 (PD-L1) antibody, in combination with tremelimumab in patients with advanced solid tumors. ASCO Meeting Abstracts. 2015 May 18;33(15_suppl):TPS3099.

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    P1.02 - Poster Session with Presenters Present (ID 454)

    • Event: WCLC 2016
    • Type: Poster Presenters Present
    • Track: Biology/Pathology
    • Presentations: 1
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      P1.02-011 - Comparison of EGFR and KRAS Mutations in Archival Tissue and Circulating Tumor DNA: The Impact of Tumor Heterogeneity (ID 4504)

      14:30 - 15:45  |  Author(s): N. Murray

      • Abstract

      Background:
      In non-small cell lung cancer (NSCLC), circulating tumour DNA (ctDNA) has gained acceptance as a potential alternative to tissue biopsies to identify targetable mutations. Individual ctDNA platforms have varying abilities to detect specific mutations. A prospective, multicenter study was conducted to determine concordance, sensitivity, and specificity of ctDNA genotyping, with archival tissue DNA (atDNA) as the reference standard.

      Methods:
      Patients with incurable advanced NSCLC at the BC Cancer Agency were enrolled over 14 months. Next-Generation Sequencing (NGS) and high-throughput multiplex amplification of a 27-gene panel (Raindance) was used for atDNA analysis. Four mL of plasma was collected in Streck (Cell Free DNA BCT) tubes for ctDNA genotyping using the Boreal Genomic OnTarget. Analysis of concordance, sensitivity, and specificity was conducted with atDNA used as the standard.

      Results:
      Seventy-six patients were enrolled, median age 66, 33 (44%) male, 69 (91%) metastatic disease, 47 (62%) with primary disease in-situ. Twenty-six EGFR mutations in 22 atDNA samples, and 12 mutations in 11 ctDNA samples were detected, with a concordance of 78%, sensitivity of 39%, and specificity 98%. One EGFR T790M mutation was positive by ctDNA alone. Twenty-one KRAS mutations in 21 atDNA samples were detected. Within this subgroup, 10 ctDNA samples had KRAS mutations with a concordance of 76%, sensitivity of 50%, and specificity of 80%. Fourteen KRAS mutations were detected by ctDNA only. The interval between archival tissue and ctDNA collection, and time between treatment and ctDNA collection, did not significantly impact the rate of concordance (p> 0.05).

      Conclusion:
      Although the sensitivity is limited, the Boreal Genomic OnTarget ctDNA analysis is specific in identifying clinically relevant EGFR mutations and has acceptable concordance rates between ctDNA and atDNA testing. Targetable EGFR and KRAS mutations were detected in ctDNA but not atDNA, which may reflect site of biopsy, tumor heterogeneity, or technical limitations of assays used. Given the high specificity and non-invasive nature of this test, positive results in EGFR mutations can be used to direct therapeutic decisions, especially accounting for clonal evolution overtime in detection of resistance mutations.