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A. Mokatrin



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    MO18 - NSCLC - Targeted Therapies IV (ID 116)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Medical Oncology
    • Presentations: 1
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      MO18.01 - An analysis of the relationship of clinical activity to baseline EGFR status, PD-L1 expression and prior treatment history in patients with non-small cell lung cancer (NSCLC) following PD-L1 blockade with MPDL3280A (anti-PDL1) (ID 2347)

      16:15 - 17:45  |  Author(s): A. Mokatrin

      • Abstract
      • Presentation
      • Slides

      Background
      NSCLC may utilize PD-L1 overexpression to escape immune surveillance. This mechanism has been suggested by recent clinical studies showing that NSCLC can respond to PD-L1/PD-1 blockade. MPDL3280A, a human monoclonal antibody containing an engineered Fc-domain designed to optimize efficacy and safety, aims to restore tumor-specific T-cell immunity by blocking PD-L1 from binding to its receptors, PD-1 and B7.1.

      Methods
      Patients received MPDL3280A IV q3w for up to 1 year in a Phase I dose escalation/expansion study. Objective response rate (ORR) was assessed by RECIST v1.1 and included unconfirmed/confirmed responses. EGFR and KRAS status was initially assessed locally by investigators. Archival tissue was analyzed centrally for PD-L1 expression by IHC.

      Results
      As of Feb 1, 2013, 52 NSCLC patients were evaluable for safety and treated at doses of 0.03-20 mg/kg. The median age of patients was 61 years (range, 24-83). 17 (33%) of patients were ECOG PS 0 and 35 (67%) of patients were ECOG PS 1. Prior treatments included surgery (89%), radiotherapy (54%) and systemic therapy (98%). 15% of patients received 1 prior regimen, 21% received 2 and 62% received ≥3. Additionally, 14%, 62% and 25% of patients were EGFR-mutation positive, EGFR WT and EGFR status unknown/undetermined, respectively, and 12%, 40% and 48% of patients were KRAS-mutation positive, KRAS WT and KRAS status unknown/undetermined, respectively. Patients received treatment with MPDL3280A for a median duration of 106 days (range 1-450). Treatment-related Gr3/4 AEs occurred in 12% of patients, including fatigue (4%) and hypoxia (4%). 1 patient experienced a Gr3/4 immune-related AE (Gr3 hyperglycemia). No Gr3-5 pneumonitis or diarrhea was reported. 41 NSCLC patients first dosed at 1-20 mg/kg prior to Aug 1, 2012, were evaluable for efficacy. An ORR of 22% (9/41) was observed in patients (squamous [n=9]/nonsquamous [n=31]) with a duration of response range of 1+ to 214+ days. Additional patients had nonconventional responses after apparent radiographic progression but were considered to have progressive disease in this analysis. All responses were ongoing or improving at data cutoff. The 24-week PFS was 46%. ORR by patient characteristics was also examined. The ORR for patients with ≤2 prior therapies was 23% (4/17) and 23% (5/22) for patients with >2 prior therapies. Additionally, the response for former/current smokers was 23% (8/35) versus 17% (1/6) for never smokers. Between EGFR-mutation positive and EGFR WT patients, the ORRs also did not differ (25% [1/4] and 19% [5/26], respectively). In contrast, PD-L1 status was associated with ORR response as patients with PD-L1–positive tumors had an ORR of 80% (4/5) and patients with PD-L1–negative tumors had an ORR of 14% (4/28). Updated data, including responses by KRAS status, will be presented.

      Conclusion
      Treatment with MPDL3280A was generally well tolerated, with no cases of Gr3-5 pneumonitis. Rapid and durable responses were observed, including in an EGFR-mutation positive patient. Responses to MPDL3280A did not appear influenced by the number of prior treatment regimens but did appear to be associated with PD-L1 tumor status. Additional studies have been initiated in NSCLC.

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    MO19 - Lung Cancer Immunobiology (ID 91)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Biology
    • Presentations: 2
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      MO19.09 - Molecular correlates of PD-L1 status and predictive biomarkers in patients with non-small cell lung cancer (NSCLC) treated with the anti-PDL1 antibody MPDL3280A (ID 1653)

      10:30 - 12:00  |  Author(s): A. Mokatrin

      • Abstract
      • Presentation
      • Slides

      Background
      In NSCLC, antitumor immune response may be inhibited by PD-L1 expression. MPDL3280A, a human monoclonal antibody containing an engineered Fc-domain designed to optimize efficacy and safety, aims to restore tumor-specific T-cell immunity by blocking PD-L1 binding to its receptors, PD-1 and B7.1.

      Methods
      Patients with squamous or nonsquamous NSCLC received MPDL3280A IV q3w up to 1 year as part of a phase I dose escalation/expansion study. Objective response rate (ORR) was assessed by RECIST v1.1 and included unconfirmed/confirmed responses. EGFR and KRAS status was initially assessed locally by investigators. Archival tumor tissues were evaluated centrally by IHC for PD-L1 and CD8. A qPCR-based gene expression panel measuring ≈90 immune-related genes was used to characterize the tumor immune microenvironment at baseline and during MPDL3280A treatment.

      Results
      41 NSCLC patients first dosed at 1-20 mg/kg prior to Aug 1, 2012, were evaluable for efficacy with an ORR of 22%. Baseline tumor samples were available for IHC (n=33) and for gene expression analysis (n=29). Of patients with available tissue, 5 were PD-L1 tumor status positive and 28 were PD-L1 tumor status negative. Relationship between PD-L1 status and EGFR/KRAS status is described below (table). Elevated baseline PD-L1 expression was associated with response to MPDL3280A (80% ORR vs 14% ORR for PD-L1negative patients), and PD-L1 expression coordinated with CD8+ T cells. A Th1-type T-cell gene signature (including CD8, Granzyme-B and EOMES) was associated with treatment response. Non-responders exhibited at least a 2-fold higher ratio over CD8 of genes associated with immunosuppression, including RORC, FOXP3, TGFb1 and IL10 compared with responders. On treatment, responding tumors across indications showed increasing PD-L1 expression and a Th1-dominant immune infiltrate, providing evidence for adaptive PD-L1 up-regulation.

      Conclusion
      PD-L1 expression and a Th1 driven T-cell gene signature correlated with response to MPDL3280A in NSCLC, and MPDL3280A therapy led to T-cell reactivation and restored antitumor immunity. Additionally, expression of immune suppressive factors in NSCLC tumors is associated with a lack of benefit from MPDL3280A. These data provide mechanistic insights into immunotherapy and patient selection for MPDL3280A monotherapy. Preliminary observations suggest clinical activity and molecular characteristics may be associated with PD-L1 tumor expression. Updated data will be presented. Table: Relationship between PD-L1 status and EGFR/KRAS mutational status

      PD-L1-Positive (n = 5) PD-L1-Negative (n = 28) PD-L1 Unknown (n = 7) Overall (n = 40)*
      EGFRm, n 1 2 1 4
      EGFR WT, n 2 20 4 26
      EGFR Unknown, n 2 6 2 10
      KRASm, n 1 4 1 6
      KRAS WT, n 2 8 3 13
      KRAS Unknown, n 2 16 3 21
      * 1 patient had missing data.

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      MO19.10 - Prevalence and prognostic association of PD-L1 protein and immune gene expression in NSCLC (ID 2437)

      10:30 - 12:00  |  Author(s): A. Mokatrin

      • Abstract
      • Presentation
      • Slides

      Background
      Programmed Death Ligand 1 (PD-L1, CD274, B7-H1) is an immune checkpoint molecule that binds to the receptors PD-1 and B7.1 on activated T cells. Binding negatively regulates T-cell function in both physiological and pathological conditions. Recent clinical studies have suggested that numerous cancers, including NSCLC, may utilize PD-L1 expression to escape T-cell mediated cytotoxic activity. Inhibition of PD-L1 can restore anti-tumor immunity, leading to clinical responses. A better understanding of PD-L1 expression patterns, co-expression with other immune markers and actionable disease associated biomarkers may provide insight into the future design of cancer immunotherapy trials in NSCLC.

      Methods
      Expression of PD-L1 was measured by immunohistochemistry (IHC) in archival tumors and, in some cases, in paired metastases in 2 FFPE NSCLC tumor tissue collections. Set 1 (N=561) was collected from patients who were eligible for surgery with curative intent from 2003 to 2005 at MD Anderson Cancer Center. The samples from Set 2 (N=300) contained surgically resected NSCLC tissue collected between 2006 and 2011 (UCCC and Norwegian Radium Hospital). PD-L1 expression was analyzed in both malignant and non-malignant cells (e.g., infiltrating immune cells). In addition, a multiplex qPCR assay that measures ≈90 immune-related genes was used to characterize the tumor immune microenvironment in the NSCLC tumor samples. Disease associated biomarkers, including the mutation status of EGFR and KRAS, as well as expression of MET (by IHC) were also evaluated.

      Results
      Prevalence of PD-L1 was comparable between adenocarcinoma and squamous cell carcinoma (≈30% in tumor cells; ≈45% and ≈50%, respectively, in immune cells). PD-L1 prevalence varied depending on the pathological stage, and was higher in Stages I-IIIA than in Stages IIIB-IV. Similarly, the prognostic value of PD-L1 varied by both stage and histology. In adenocarcinoma, tumors with PD-L1–positive tumor cells had a higher frequency of KRAS mutation and high Met expression, and a lower frequency of EGFR mutation compared with PD-L1–negative tumors. In contrast, tumors with PD-L1–positive and PD-L1–negative immune cells had a comparable frequency of high Met expression. Expression of PD-L1 was frequently co-localized with CD8+ T-cell infiltrates. Gene expression profiling revealed differences in the tumor immune environment, including genes associated with cytotoxic T-cells, between adenocarcinomas and squamous cell carcinomas. PD-L1 protein and immune gene expression associations with patient characteristics will be described in further detail.

      Conclusion
      These data provide a comprehensive description of PD-L1 expression in the context of disease biology utilizing large independent cohorts of well-characterized lung cancer tissues. The results highlight the complexity of the tumor immune environment in NSCLC with particular emphasis on the association with factors such as pathological stage, histology and oncogenic mutational status. These analyses may help guide future development of immunotherapy trials in NSCLC.

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