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K. Politi
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MA15 - Immunotherapy Prediction (ID 400)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Chemotherapy/Targeted Therapy/Immunotherapy
- Presentations: 2
- Moderators:O. Arrieta
- Coordinates: 12/07/2016, 14:20 - 15:50, Schubert 1
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MA15.06 - Predictive Value of Measuring Somatic Mutations and Tumor Infiltrating Lymphocytes for PD-1 Axis Therapy in Non-Small Cell Lung Cancer (NSCLC) (ID 6255)
14:56 - 15:02 | Author(s): K. Politi
- Abstract
Background:
Diverse factors have been associated with clinical benefit to PD-1 axis blockers in NSCLC including PD-L1 protein expression by immunohistochemistry and increased mutation load/predicted class-I neoantigens. However, the association and predictive value of the tumor genomic landscape, composition of the tumor immune microenvironment and T-cell function remain unclear.
Methods:
We performed whole exome DNA sequencing and multiplexed quantitative immunofluorescence (QIF) for T-cells in pre-treatment FFPE samples from 45 NSCLC patients treated with PD-1 axis blockers (alone or in combination) in our institution. Genomic analysis was used to evaluate the mutational load and predicted class-I neoantigens. Multiplexed QIF-based immunoprofiling was used to measure the level of CD3+ tumor infiltrating lymphocytes (TILs), in situ T-cell proliferation (Ki-67 in CD3+ cells) and T-cell activation (Granzyme-B in CD3+ cells). We studied the association between the tumor somatic mutations, predicted neoantigens, T-cell infiltration/function and clinical benefit /survival.
Results:
Increased mutational load was positively associated with predicted class-I neoantigens, variants in DNA-repair genes, smoking and absence of activating mutations in EGFR; but not associated with the level of CD3+ T-cells, T-cell proliferation (Ki-67 in CD3+ cells) and function (Granzyme-B in CD3+ cells). Increased mutations and candidate class-I neoantigens were significantly associated with response to therapy (P=0.02 and 0.03, respectively), but not with overall survival at 3-years (median cut-point, log rank P=0.92 and 0.80, respectively). Higher CD3 positivity was not associated with response to therapy (P=0.17), but was significantly associated with overall survival (median cut-point, log rank P=0.03). Regardless of the mutational load and candidate neoantigen content, elevated CD3 with low Ki-67/Granzyme-B in CD3 predicted longer survival after PD-1 axis blockade than high CD3/high Ki-67/Granzyme-B in CD3, or low T-lymphocyte infiltration.
Conclusion:
Increased somatic mutations are associated with smoking and response to PD-1 agents, but not with tumor T-cell infiltration/activation and overall survival. Regardless of the mutational load, increased T-cell infiltration using QIF is significantly associated with longer survival after PD-1 axis blockade in NSCLC. The subgroup of NSCLC with the highest potential of benefit to immune reinvigoration using PD-1 axis blockade comprise tumors with elevated lymphocyte infiltration but low in situ activation/proliferation.
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MA15.11 - Acquired Resistance Mechanisms to EGFR Kinase Inhibitors Alter PD-L1 Expression Status in Lung Cancer (ID 4652)
15:32 - 15:38 | Author(s): K. Politi
- Abstract
Background:
Immunotherapies that target PD-1/PD-L1 exploit the primary roles of cytotoxic agents in lung cancers. However, tyrosine kinase inhibitors (TKIs) are still considered to be the first choice in lung cancer patients with EGFR mutations. Although immunotherapies may be applied as second line or later therapeutic approaches in these patients, after acquisition of resistance to EGFR-TKIs, it is unclear if acquired resistance mechanisms alter PD-L1 expression status that is employed as an important predictive biomarker for PD-1/PD-L1 targeting agents.
Methods:
Lung cancer cell lines with EGFR mutations (HCC827, HCC4006, PC9, and H1975) and their isogenic descendants with acquired resistance to various EGFR-TKIs were examined in this study. The resistance mechanisms of descendants include T790M secondary mutation, MET gene amplification, epithelial to mesenchymal transition (EMT), and loss of amplified EGFR mutant allele. PD-L1 expression status was analyzed by immunohistochemistry (IHC) and immunoblotting. Effects of acquired resistance mechanisms on PD-L1 expression were also evaluated by shRNA mediated knockdown of candidate molecules, and co-localization analysis using fluorescent imaging. IFN-gamma was used to mimic immune cell attack. Published microarray data of cells with acquired resistance to EGFR-TKIs were also employed to evaluate our findings.
Results:
PD-L1 expression was upregulated in several resistant cells and correlated with EGFR activation. In addition, we found that the phosphorylation of EGFR tyrosine (Y) 992 site, but not Y845, Y1068, or Y1173, was correlated with increased expression of PD-L1. We also observed that TKI-resistant cells with marked E-cadherin downregulation (HCC4006 erlotinib resistant cells and H1975 osimertinib resistant cells), one of hallmarks of EMT, showed decreased expression of PD-L1. However, one cell line (853#10), displaying EMT-like phenotype but only slight E-cadherin downregulation, showed PD-L1 upregulation. Published microarray data from three TKI-resistant lines with EMT-like features also support the correlation of low E-cadherin and reduced PD-L1 expression. ShRNA mediated knockdown of E-cadherin decreased the expression of PD-L1 in parental cell lines. IFN-gamma treatment upregulated PD-L1 expression in both parental and in resistant cells with E-cadherin downregulation, however PD-L1 expression in resistant cells was still lower and localized mainly in the cytoplasm rather than the cell membrane.
Conclusion:
We observed a dramatic change of PD-L1 expression status in lung cancers with EGFR mutation after acquisition of resistance to EGFR-TKIs, depending on the resistance mechanisms. These results support the importance of re-biopsy after acquisition of resistance to EGFR-TKIs, not only for the resistance mechanisms but also for the evaluation of PD-L1 expression status.
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MA16 - Novel Strategies in Targeted Therapy (ID 407)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Chemotherapy/Targeted Therapy/Immunotherapy
- Presentations: 1
- Moderators:G. Purkalne, J. Von Pawel
- Coordinates: 12/07/2016, 14:20 - 15:50, Strauss 2
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MA16.02 - Mutational Landscape of TKI Naïve and Resistant EGFR Mutant Lung Adenocarcinomas (ID 5777)
15:44 - 15:50 | Author(s): K. Politi
- Abstract
- Presentation
Background:
The identification and development of tyrosine kinase inhibitors (TKIs) targeting the epidermal growth factor receptor (EGFR) have revolutionized and greatly improved the treatment of EGFR-mutant non-small cell lung cancer (NSCLC). Unfortunately, acquired resistance (AR) to these agents remains a major clinical problem hindering durable responses. Although significant work has been done to identify particular mechanisms of acquired resistance, little is known regarding the global mutational landscape of EGFR mutant tumors before therapy or at the manifestation of acquired resistance.
Methods:
Using specimens obtained in the IRB approved, Yale Lung Rebiopsy program, we completed whole exome sequencing of 15 EGFR mutant tumors with paired tissue obtained pre-treatment and at the time of AR to EGFR TKIs. An additional 5 unpaired AR samples were also analyzed. The mutational burden and copy number profile of the specimens were studied.
Results:
We found that the mutational burden of pre-treatment EGFR mutant tumors varies widely between tumors. TKI treatment, however, does not significantly alter the overall or non-synonymous mutation load at AR. Interestingly, EGFR[L858R]tumors had a significantly higher mutation burden at acquired resistance to EGFR TKIs than EGFR[Δ19] tumors. The higher mutation burden in EGFR[L858R] tumors compared to those harboring EGFR[Δ19 ]mutations was further confirmed through analysis of TCGA data. Recurrently altered genes shared in the pre- and AR specimens include TP53, EGFR and AKT1. Alterations in EGFR (T790M), MYCBP2, WHSC1L1, AXL, MET, HGF, MYC and NTRK1 were found at exclusively at AR.
Conclusion:
Collectively, these data provide valuable insight into the mutational landscape of EGFR mutant NSCLCs as they evolve on TKIs and identify potential resistance candidate genes for further investigation.
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P3.01 - Poster Session with Presenters Present (ID 469)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Biology/Pathology
- Presentations: 1
- Moderators:
- Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)
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P3.01-049 - ELF3 Overexpression Leads to Oncogenic Reprogramming of Protein Interactions Exposing Therapeutically Actionable Targets (ID 5807)
14:30 - 14:30 | Author(s): K. Politi
- Abstract
Background:
Emerging evidence has implicated ELF3 involvement in cancer signaling pathways. To determine the biological basis to pursue ELF3 as a novel therapeutic target, we investigated the role of ELF3 in lung adenocarcinoma (LUAD). Using a multi-omics approach in two independent cohorts of LUAD we (a) discover genetic mechanisms driving aberrant expression of this oncogene, (b) identify the protein-protein-interaction (PPI) partners of ELF3, and (c) determine the specific functions of ELF3 in LUAD using model systems.
Methods:
Comprehensive, multi-omic data was collected from the BC Cancer Research Centre (BCCRC), The Cancer Genome Atlas (TCGA), and several mouse models of LUAD tumourigenesis. ELF3 cellular localization was visualized by immunofluorescence. ELF3 knock-down and overexpression was achieved by lentiviral vector delivery for in vitro and in vivo assays. Physical protein-protein interaction (PPI) networks obtained from IID were overlaid onto cancer and non-malignant gene expression data from TCGA and 11 restructured datasets from Gene Expression Omnibus. PPIs were interrogated to investigate malignancy-associated ELF3 interactions. Pathway analysis was performed using pathDIP. Survival analysis was performed using the log-rank method.
Results:
ELF3 was significantly overexpressed in both cohorts, remarkably in >70% of cases (p=1.64E-21). However, mutation of known upstream regulators was not sufficient to explain the frequency of ELF3 overexpression. Instead, the ELF3 locus underwent frequent (>80%) genetic alteration including focal amplification and promoter hypomethylation, which corresponded with increased expression. ELF3 was predominantly localized to the nucleus, consistent with its transcription factor function. Analysis of PPI networks indicated highly LUAD-specific ELF3 interactions whereby loss and gain of interactions lead to reprogramming of LUAD transcriptional networks, including loss of TNFα pathway, and gain of TGFβ pathway, PI3K pathway, and translesion (DNA repair) pathway interactions. Furthermore, EGFR, KRAS, and MYC transgenic models of LUAD tumourigenesis all displayed a marked increase (6 to 8-fold) in ELF3 expression signifying its importance to LUAD of varied genetic backgrounds. In culture, ELF3 regulated proliferation, viability and anchorage-independent growth. In animal models, ELF3 knock-down cells underwent negative clonal selection, suggesting ELF3 expression is beneficial to tumour growth. Clinically, high expression of ELF3 was associated with poor survival regardless of tumour stage.
Conclusion:
Overexpression of ELF3 reprograms protein-protein-interactions in LUAD leading to the activation of cancer-specific pathways, and producing oncogenic phenotypes. Depletion of ELF3 with shRNAs reverses tumour cell growth, suggesting ELF3 is a promising therapeutic target. In addition to ELF3, interruption of cancer-specific PPIs also represents a therapeutically actionable strategy.
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P3.02b - Poster Session with Presenters Present (ID 494)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Advanced NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)
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P3.02b-052 - Afatinib with or without Cetuximab for First-Line Treatment of EGFR-Mutant NSCLC: Interim Safety Results of SWOG S1403 (ID 5798)
14:30 - 14:30 | Author(s): K. Politi
- Abstract
Background:
Afatinib is used as first-line therapy for EGFR-mutant non-small cell lung cancer (NSCLC), however resistance invariably develops. To attempt to delay resistance and improve survival, we are conducting a randomized Phase II/III trial of afatinib plus cetuximab versus afatinib alone in treatment-naïve patients with advanced EGFR-mutant NSCLC (NCT02438722).
Methods:
Previously untreated patients with EGFR exon 19 deletion or L858R point mutation are randomized to afatinib 40mg PO daily plus cetuximab 500mg/m2 IV every 2 weeks (afat/cetux) or afatinib 40mg PO daily (afat). Dose reductions are performed for grade 3-4 or intolerable or medically concerning grade 2 adverse events (AEs) per CTCAE v4.0. The Phase II primary endpoint is progression-free survival and the Phase III primary endpoint is overall survival. Here we review the safety data after enrollment of the first 53 patients.
Results:
53 patients were registered as of June 30, 2016, and safety has been assessed in 47 (23 treated with afat/cetux and 24 with afat, see Table). Grade 1-2 rash occurred in 71% of patients receiving afat/cetux and 63% of patients on afat. Grade 3 rash was noted in 22% of patients on afat/cetux. Fatigue was more common in the combination arm; all occurrences were grade 1-2. Grade 1-2 diarrhea and other gastrointestinal AEs were comparable between the two arms. There were similar numbers of dose reductions for AEs on each arm. Three patients discontinued treatment due to AEs: 2 on the afat/cetux arm due to hyperglycemia and accumulated side effects and 1 on the afat arm due to weight loss and diarrhea. Figure 1
Conclusion:
In this randomized trial of afat/cetux versus afat, treatment was tolerable in both arms of the study. Skin toxicity appears to be worse with the combination however other AEs are similar between the two groups. Enrollment to this trial is ongoing.
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P3.02c - Poster Session with Presenters Present (ID 472)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Advanced NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)
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P3.02c-088 - Acquired Resistance to Programmed Death-1 Axis Inhibitors in Non-Small Cell Lung Cancer (NSCLC) (ID 5625)
14:30 - 14:30 | Author(s): K. Politi
- Abstract
Background:
Programmed death-1 (PD-1) axis inhibitors are increasingly being used to treat patients with advanced NSCLC. Despite durable responses relative to chemotherapy, resistance to such therapy develops in the majority of responders, with median duration of response from 12-17 months. Mechanisms of acquired resistance (AR) to PD-1 axis inhibitors are poorly understood.
Methods:
Patients with advanced NSCLC and acquired resistance (AR) to PD-1 axis inhibitor therapy were enrolled to an IRB approved repeat biopsy protocol allowing collection of clinical data, archived and fresh tumor tissue, and blood for analysis. Molecular analyses including whole exome sequencing of pre- and post-treatment tumor specimens were performed.
Results:
Twelve cases were available for analysis (table 1). Eight and two patients developed resistance limited to lymph nodes (LNs) and adrenal gland respectively. The two remaining patients experienced tumor progression in LNs with other sites of tumor growth (one in liver, one in lung). Nine patients had sufficient archived pre- PD-1 axis inhibitor tumor tissue for analysis/ comparison, leaving three unpaired cases. Genomic analysis of tumor specimens identified two patients with acquired tumor beta-2-microglobulin (B2M) defects at resistance. A patient derived xenograft generated from one of the resistance samples (patient #6) lacked production of B2M protein and did not express surface MHC-1. Additional analyses including immunophenotyping with multiplexed quantitative immunofluorescence on these and other patient samples are ongoing. Figure 1
Conclusion:
Lymph nodes may be a particularly susceptible area to AR to PD-1 axis inhibitors. Defects in B2M leading to loss of tumor MHC-1 presentation may represent a unique mechanism of AR to immune checkpoint inhibitors. Further studies to determine the frequency of defects in antigen presentation machinery in tumors with resistance to PD1 axis inhibitors are warranted.
