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M.J. Mooradian
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OA 07 - Biomarker for Lung Cancer (ID 659)
- Event: WCLC 2017
- Type: Oral
- Track: Biology/Pathology
- Presentations: 1
- Moderators:Philip Christopher Mack, Shinichi Toyooka
- Coordinates: 10/16/2017, 15:45 - 17:30, Room 503
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OA 07.05 - Serial Biopsies in Patients with EGFR-Mutant NSCLC Highlight the Spatial and Temporal Heterogeneity of Resistance Mechanisms (ID 10181)
15:45 - 17:30 | Author(s): M.J. Mooradian
- Abstract
- Presentation
Background:
Resistance to EGFR tyrosine kinase inhibitors (TKIs) limits treatment outcomes among patients with EGFR-mutant NSCLC. Resistance mechanisms have previously been conceptualized as binary “positive/negative” variables, but emerging evidence suggests resistant cancers are heterogeneous, and subclones may be appreciated through multiple biopsies.
Method:
We retrospectively analyzed 221 EGFR mutant pts at MGH who had >1 biopsy after progression on their initial EGFR inhibitor. Data on acquired resistance (AR) mechanisms observed at each biopsy, adverse events, and treatment were collected.
Result:
Among 221 pts with a total of 355 post-AR tissue biopsies, median age was 59 (range, 28-88), 69% were female, 64% had EGFR del19, 33% L858R and 3% other activating mutations. Median number of biopsies per patient was 1 (range, 1-4). Biopsies at first resistance to EGFR TKI showed 61% T790M, 5% MET amplification (amp), 3% SCLC transformation, 2% acquired PIK3CA and 1% acquired BRAF mutations. 83 pts had two biopsies during their post-resistance course; 43/83 (52%) had heterogeneity between biopsy 1 and 2. In particular, 20% “lost” T790M, while 11% “gained” T790M. Among 17 pts who lost T790M, 3 gained a separate resistance mechanism, including MET amp and BRAF V600E. In some cases, synchronous biopsies identified spatial heterogeneity. For example, an osimertinib-resistant patient had a T790M/C797S lung nodule, while a concurrent mediastinal lymph node was wild-type at both loci (both sites retained the activating EGFR mutation). Similarly, another osimertinib-resistant patient with MET amp in a pleural effusion cell block had a lung nodule biopsy which lacked MET amp; the patient was treated with combination EGFR and MET inhibitors with a partial response. Additional details regarding concurrent liquid biopsies, treatment histories and clinical outcomes will be presented.
Conclusion:
In this large cohort of EGFR mutant NSCLC patients, we frequently observed variations in resistance mechanisms in patients with > 1 post-AR biopsy. Our data highlights the heterogeneity of resistant cancers and the limitations of a single biopsy in fully capturing the spectrum of resistance mechanisms in each patient. Serial biopsies or non-invasive methods may be required to characterize resistance and identify potential therapeutic targets.
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P1.07 - Immunology and Immunotherapy (ID 693)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Immunology and Immunotherapy
- Presentations: 1
- Moderators:
- Coordinates: 10/16/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P1.07-033 - Differential Expression of Immune Inhibitory Markers in Association with the Immune Microenvironment in Resected Lung Adenocarcinomas (ID 10196)
09:30 - 16:00 | Author(s): M.J. Mooradian
- Abstract
Background:
Similar to programed death ligand 1 (PD-L1), indoleamine 2,3-Dioxygenase 1 (IDO1) is known to exert immunosuppressive effects and be variably expressed in human lung cancer. However, IDO1 expression has not been well-studied in lung adenocarcinoma (ADC).
Method:
PD-L1 and IDO1 expression were evaluated in 261 resected ADC using tissue microarrays and H-scores (cutoff 5). We compared IDO1 with PD-L1 expression in association with clinical features, tumor-infiltrating lymphocytes (TILs), HLA class I (β-2 microglobulin; B2M) expression, molecular alterations, and patient outcomes.
Result:
There was expression of PD-L1 in 89 (34.1%) and IDO1 in 74 (28.5%) cases, with co-expression in 49 (18.8%). Both PD-L1 and IDO1 were significantly associated with smoking, aggressive pathologic features, and abundant CD8+ and T-bet+ (Th1 marker) TILs. PD-L1 expression and abundant CD8+ were inversely associated with a loss of B2M membranous expression (p=0.002 and p<0.001, respectively). Compared to PD-L1+/IDO1+ and PD-L1+ only cases, significantly fewer IDO1+ only cases had abundant CD8+ and T-bet+ TILs (p<0.001, respectively). PD-L1 expression was significantly associated with EGFR wild-type (p<0.001) and KRAS mutants (p=0.021), whereas there was no difference in IDO1 expression between different molecular alterations. As for survival, PD-L1 was significantly associated with decreased progression-free (PFS) and overall survival (OS), while IDO1 was associated only with decreased OS. Interestingly, there was a significant difference in the 5-year PFS and OS (p=0.004 and 0.038, respectively), where cases without PD-L1 or IDO1 expression had the longest survival, and those with PD-L1 alone had the shortest survival.
Conclusion:
While PD-L1 +/- IDO1 expression is observed in association with B2M expression, CTL/Th1 microenvironments, EGFR wild-type, and KRAS mutations, isolated IDO1 expression does not demonstrate these associations. These results suggest that IDO1 may serve a distinct immunosuppressive role in ADC. Thus, blockade of IDO1 may represent an alternative and/or complementary therapeutic strategy to reactivate anti-tumor immunity. Additional study to examine a larger number of immunoregulatory markers is ongoing.
