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ORAL 02 - PD1 Axis Immunotherapy 2 (ID 87)
- Event: WCLC 2015
- Type: Oral Session
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
ORAL02.06 - Evaluation of PD-L1 Expression in Metachronous Tumor Samples and FDG-PET as a Predictive Biomarker in Ph2 Study (FIR) of Atezolizumab (MPDL3280A) (ID 2207)
10:45 - 12:15 | Author(s): M. Kowanetz
PD-L1 expression on tumor-infiltrating immune cells (IC) and/or tumor cells (TC) can inhibit antitumor immunity. Atezolizumab (MPDL3280A) is an anti-PDL1 antibody that has shown efficacy across multiple tumor types. The efficacy and safety of atezolizumab in the Phase 2 FIR study has been reported previously (Spigel et al, ASCO 2015). Efficacy appeared to correlate with PD-L1 expression on IC and/or TC, with higher ORRs observed in patients with the highest expression of PD-L1, indicating that PD-L1 may be a predictive biomarker for response to atezolizumab. FIR was also designed to address questions of potential heterogeneity and changes in tumor PD-L1 expression in metachronous tissue samples, as well as the utility of using FDG-PET as a biomarker for response to atezolizumab in PD-L1–selected patients with NSCLC.
FIR is a 3-cohort, single-arm, Phase 2 study of atezolizumab in PD-L1–selected patients with stage IIIB/IV NSCLC. Cohort 1 included chemo-naive patients, Cohort 2 included ≥ 2L patients without a history of brain metastases, and Cohort 3 included ≥ 2L patients with asymptomatic treated brain metastases. PD-L1 expression was centrally assessed by immunohistochemistry (IHC) using the SP142 antibody assay in archival and/or fresh tumor biopsies or resections and scored as IC0, 1, 2 or 3 and TC0, 1, 2 or 3. Patients with PD-L1 IC2/3 or TC2/3 tumors were enrolled and received 1200 mg atezolizumab IV every 3 weeks (last patient entered Jun 27, 2014). Responses were measured by RECIST v1.1, modified RECIST and FDG-PET using EORTC criteria. Exploratory objectives included the evaluation of potential predictive biomarkers, including the comparison of PD-L1 expression in matched archival and fresh tumor specimens, as well as the utility of FDG-PET in assessing response to immune checkpoint blockade.
From 1009 screened patients, 95 paired archival and fresh tumor samples were obtained. In these samples, the agreement of PD-L1 expression between fresh and archival tissue at the TC3 or IC3 cutoff was 88% when the same type of tissue procurement method was used (resection or biopsy), compared with 65% when different methods of procurement were used. To date, FDG-PET response has been centrally assessed in 71 of the 138 patients enrolled in FIR. Patients with metabolic response by EORTC criteria on 6-week scans had a higher ORR per RECIST v1.1 (72% [13/18]) than metabolic non-responders (ORR 4% [2/53]).
There was a high agreement in TC3 or IC3 PD-L1 expression between archival and fresh tumor specimens. This work demonstrates that intra-patient heterogeneity in PD-L1 expression is low in metachronous tissues, indicating various types of tumor samples, including fresh or archival, can be reliably used to assess PD-L1 expression. In addition, FDG-PET has potential as an early on-treatment measure of response to atezolizumab. Further analyses will be presented. (NCT01846416)
ORAL 13 - Immunotherapy Biomarkers (ID 104)
- Event: WCLC 2015
- Type: Oral Session
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
ORAL13.03 - Spatiotemporal Effects on Programmed Death Ligand 1 (PD-L1) Expression and Immunophenotype of Non-Small Cell Lung Cancer (NSCLC) (ID 1609)
16:45 - 18:15 | Author(s): M. Kowanetz
PD-L1 is one of the immune-checkpoint molecules that regulates Th1 immune responses and mediates cancer immune evasion. PD-L1 can be expressed on tumor cells (TC) or tumor-infiltrating immune cells (IC) and expression in both cell types can negatively regulate T-cell function in the tumor microenvironment. The goal of this study was to evaluate the intra-patient heterogeneity and temporal changes in PD-L1 expression and overall immune phenotype in NSCLC using paired synchronous and metachronous tumor specimens.
Thirty-nine patients (pts) with NSCLC treated at Memorial Sloan Kettering Cancer Center were evaluated as part of an IRB approved project. Most were former/current smokers (n=30, 77%) and had adenocarcinoma histology (n=36, 92%). 17 pts were KRAS mutant (45%), and 5 were EGFR mutant (13%). Paired synchronous samples were collected from 17 pts with stage IIIA-N2 resected primary lung and metastatic lymph node (met LN) tissue. Paired metachronous samples were collected from 23 pts (including one patient also with synchronous tissue) with at least two metachronous primary/metastatic (n=14) or metastatic/metastatic tissues (n=9). In pts with metachronous samples, 14 (61%) had systemic intercurrent anti-cancer therapy and 9 (39%) had none. PD-L1 expression was assessed by IHC (clone SP142) on TC and IC. CD8 expression was evaluated by IHC using the C8/144 clone. In addition, expression of ~600 immune genes was analyzed by iChip.
Twenty-five out of 39 tissue pairs were evaluable by PD-L1 IHC (14/17 synchronous, 11/23 metachronous). Among pts with synchronous samples, in the primary tumor, PD-L1 was expressed in <1% of TC or IC in 6 pts, in 1-4% of cells in 5 pts, and in ≥5% of cells in 3 pts. Among those with metachronous samples, in the first collected sample, the PD-L1 expression in <1% of TC or IC was detected in 6 pts, in 1-4% of cells in 2 pts, and in ≥5% of cells in 3 pts. PD-L1 expression was similar across all paired tissues. PD-L1 status at the TC or IC 5% cut-off remained unchanged in all evaluable paired specimens and at the TC or IC 1% cut-off remained unchanged in 80% (11/14 synchronous and 9/11 metachronous) pairs. In both synchronous and metachronous samples, CD8 expression was also similar across paired specimens. The median inter-sample difference in CD8+ T-cell infiltration was 0.5% (95% CI: -0.6% - 3.4%) in synchronous pairs; three pts had a difference >5%. In metachronous pairs, the median difference was -0.4% (95% CI: -1.4% - 0.1%); one pt had a >5% change in CD8+ T-cell infiltration.
In this study, there was a high agreement in PD-L1 expression and CD8+ T-cell infiltration in both paired synchronous and metachronous NSCLC specimens. The low intra-patient heterogeneity of PD-L1 and CD8 expression in this study suggests any available tissue (e.g. primary or met) may be reliable to assess these markers in NSCLC. Overall immune characterization by gene expression analysis in paired tumor specimens will be presented.