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MO19 - Lung Cancer Immunobiology (ID 91)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Biology
- Presentations: 1
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): C. Cruz
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.
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.
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.
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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