EGFR-mutant Tumors Research Articles

Abstract B007: Proximal RTK signaling regulates tumor initiating cell survival and therapeutic responsiveness in EGFR- and KRAS-mutated lung adenocarcinoma

Abstract Lung cancer is the leading cause of cancer-related death worldwide; adenocarcinoma is the most common subtype of lung cancer. Oncogenic driver mutations in the RTK/RAS pathway occur in 75-90% of LUAD. Oncogene-targeted therapies substantially improve outcomes in LUAD; however, recalcitrant tumors invariably emerge necessitating novel therapeutic approaches that either delay therapeutic resistance or treat resistant cancers to enhance patient outcomes. Resistance to oncogene-targeted therapies in LUAD is commonly due to RTK pathway reactivation. Resistance to osimertinib in EGFR-mutated tumors, KRASG12C inhibitors (sotorasib, adagrasib) in KRASG12C-mutated tumors, or MEK inhibitors (trametinib) in KRAS (non-G12C)-mutated tumors often develops via activation of multiple RTKs. The multiplicity of RTKs that can be activated to drive resistance suggests that individual RTK inhibitors will be ineffective alone, while broad inhibition of RTK signaling can enhance the efficacy of and delay resistance to targeted therapies in LUAD. Tumor initiating cells (TICs) are a functional subset of LUAD cells that exhibit self-renewal and are recalcitrant to oncogene-targeted therapies; it has been hypothesized that therapy-resistant TICs are the sanctuary population within the bulk tumor responsible for therapeutic resistance. Targeted ablation of TICs has the potential to enhance the efficacy of and delay resistance to targeted therapies in LUAD. We found that proximal RTK inhibition (SOS1-I and/or SOS2 KO) enhanced the killing effect of oncogene-targeted therapies under 3D culture conditions. SOS1 inhibition and/or SOS2 KO further delayed resistance to oncogenic targeted therapies in both EGFR- and KRASG12C-mutated cell lines. Since TICs are proposed as driving therapeutic resistance, these data suggested that SOS1/2 may regulate TIC survival. TICs can be functionally defined by their ability to proliferate in 3D culture from a single cell. Using this functional definition, we found that 72-h treatment with the G12C-Is adagrasib or sotorasib enriched for functional TICs 2-3 fold in multiple KRASG12C-mutated cell lines, suggesting that TICs could act as a sanctuary population of G12C-I resistant cells. We further isolated cells based on ALDH activity and found isolated ALDHhigh TICs are markedly recalcitrant to short-term G12C-I treatment. In both cases, we found that SOS1-I and/or SOS2 KO inhibited the recalcitrance of TICs to G12C inhibitors to synergistically inhibit TIC survival. These data suggest that SOS1 inhibition and/or SOS2 KO impedes the development of resistance to oncogenic targeted therapy by targeting TIC outgrowth. Citation Format: Brianna Daley, Rob Kortum. Proximal RTK signaling regulates tumor initiating cell survival and therapeutic responsiveness in EGFR- and KRAS-mutated lung adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference: Targeting RAS; 2023 Mar 5-8; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Res 2023;21(5_Suppl):Abstract nr B007.

Targeted Therapy for Metastatic Non–Small Cell Lung Cancer

The use of next-generation tyrosine kinase inhibitors has led to improved progression-free survival for patients with metastatic non–small cell lung cancer (NSCLC) and those with EGFR-mutant and ALK-positive tumors. Newer therapeutics can now target KRAS G12C mutations, EGFR exon 20 insertions, and ERBB2 (HER2) mutations. Patients with metastatic NSCLC should undergo molecular testing for these mutations as well as for BRAF mutations; MET exon 14 skipping alterations; and ROS1, RET, and NTRK gene rearrangements (fusions). Novel targeted therapeutics are emerging at a fast pace.

Abstract 1479: FOXA2 induces invasive mucinous adenocarcinoma of the lung in the presence of mutant KRAS

Abstract Introduction: The role of the endoderm lineage transcription factor FOXA2 in autochthonous lung tumors has been elusive though the expression of FOXA2 has been reported in human lung cancers. Here, using GEMM (Genetically Engineered Mouse Models) and human lung cancer cell lines, we delineate the role of FOXA2 in lung cancers. Experimental Procedures: GEMM that carry mutant KRAS or mutant EGFR along with FOXA2 (CCSP-rtTA; tetO-Foxa2; tetO-Kras.G12D or tetO-EGFR.L858R) were developed allowing for lung tumor induction by doxycycline administration. The growth of lung tumors affected by FOXA2 was assessed by microCT and pathologically. FOXA2 downstream genes were also evaluated in vivo by immunohistochemistry of mouse lung sections and in vitro by gain (ectopic lentivirus transduction) and loss (siRNA) of function approaches with human lung cancer cell lines using TaqMan gene expression, RNA-seq, ChIP-seq and CRISPRi analyses. FOXA2 protein expression in human lung cancer specimens was also assessed. Data: FOXA2 suppressed the growth of EGFR-mutant lung tumors while promoting that of KRAS-mutant lung tumors in GEMM. Notably, half of the KRAS-mutant lung tumors presented invasive mucinous adenocarcinoma of the lung (IMA) with the expression of a master mucous transcription factor SPDEF and the two major IMA mucin genes MUC5AC and MUC5B. In vitro, FOXA2 induced the expression of SPDEF, MUC5AC and MUC5B by directly binding to their loci. H3K27ac was introduced at the enhancer region of MUC5AC (most highly expressed IMA gene) by FOXA2 and the expression of MUC5AC initiated by FOXA2 was enhanced by mutant KRAS. FOXA2 was highly expressed in human IMA compared to normal lung. Conclusions: FOXA2 induces IMA in the presence of mutant KRAS by directly regulating the expression of mucous genes. Citation Format: Yutaka Maeda, Koichi Tomoshige, William D. Stuart, Iris M. Fink-Baldauf, Masaoki Ito, Tomoshi Tsuchiya, Takeshi Nagayasu, Tomoki Yamatsuji, Morihito Okada, Takuya Fukazawa, Minzhe Guo. FOXA2 induces invasive mucinous adenocarcinoma of the lung in the presence of mutant KRAS [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1479.

Abstract 771: Mechanisms of genetic predisposition to multifocal lung cancer

Abstract Detection of multiple primary lung cancers is increasing in frequency, with up to 15% of all non-small cell lung cancer (NSCLC) patients presenting with two or more anatomically separate tumor nodules on CT scans. Increased detection is in part due to expanded lung cancer screening criteria in an aging population. Distinguishing multiple primary tumors from intrapulmonary metastases can be challenging, yet is critical for determining clinical management. Current models predict development of multiple primary tumors out of a cancerized field, such as occurs due to smoking. The occurrence of multiple primary tumors is unexplained in patients with EGFR-mutant lung cancer (~15% of all NSCLC), lacking environmental exposures. We identified patients with non-small cell lung cancer (NSCLC) who presented with multiple primary EGFR-mutant tumors, in the absence of family history of lung cancer or heavy smoking. We subjected the macrodissected tumors and surrounding normal tissues to whole exome sequencing as well as to analysis of hypermutable poly-guanine (poly-G) repeats, which are two orthogonal methods of lineage tracing. An additional familial case with a germline EGFR-T790M mutation was used to establish parameters for timing of somatic mutations, and functional properties of novel germline variants were modeled in vitro. Of eleven non-familial NSCLC cases with two or more geographically distinct EGFR-mutant lung cancers, two patients harbored a germline EGFR variant allele, which confers moderately enhanced signaling in vitro, followed by a somatically acquired EGFR mutation. In an additional four cases, both whole exome sequencing and poly-G repeat analyses indicate a distant shared somatic cell-of-origin, consistent with embryonic mosaicism. Three cases revealed clinically unappreciated metastasis and two cases remain unexplained. Together, our data suggest that multiple primary lung cancers with somatic EGFR driver mutations may result from genetic susceptibility, attributable either to attenuated EGFR germline variants or to embryonic mosaicism resulting in geographically disparate patches of predisposed lung tissue. Such predisposed cases should be surveilled for early detection of future tumors, and surgical resection in these cases should consider the life-long risk of additional cancers. Citation Format: Risa Burr, Ignaty Leshchiner, Christina L. Costantino, Martin Blohmer, Tilak Sundaresan, Justin Cha, Karsen Seeger, Sara Guay, Brian P. Danysh, Ira Gore, Raquel A. Jacobs, Kara Slowik, Filippo Utro, Kahn Rhrissorrakrai, Chaya Levovitz, Jaimie L. Barth, Taronish Dubash, Brian Chirn, Laxmi Parida, Lecia V. Sequist, Mari Mino-Kenudson, Kamila Naxerova, Shyamala Maheswaran, Gad Getz, Daniel A. Haber. Mechanisms of genetic predisposition to multifocal lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 771.

Abstract 3864: Targeting IL-6/STAT3 signaling in EGFR-mutant drug tolerant persister cells

Abstract While the majority of epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC) patients initially respond to treatment with an EGFR tyrosine kinase inhibitor (TKI), most will eventually develop acquired resistance to these agents. The evolution of tumor cells with acquired resistance to targeted agents initially involves the persistence of a drug-tolerant subpopulation of tumor cells which display a transient and flexible resistant state. These persister cells can remain quiescent for prolonged periods of time, but eventually give rise to fully drug resistant tumor cells that resume growth and metastatic spread. The signaling pathways that allow persister cells to remain viable or to re-activate expansive growth are poorly understood. We and others have reported that EGFR TKI resistance that occurs independent of secondary EGFR mutations or MET amplification is associated with an epithelial to mesenchymal transition (EMT). Our analysis of tumor cells that had undergone EMT-mediated resistance to the EGFR TKI osimertinib revealed that interleukin-6 (IL-6) was highly upregulated in resistant cells as compared to parental cells. We find that in the setting of EGFR mutant NSCLC, IL-6 suppresses the anti-tumor cell activity of T cells and NK cells. To assess the role of IL-6 in the early events of EGFR TKI resistance, we generated drug-tolerant persister cells by treating EGFR mutant HCC4006 and HCC827 NSCLC cells with the EGFR TKI osimertinib for 10 days and then assessed IL-6 expression. We observed that IL-6 was upregulated at both the RNA and protein levels in EGFR-TKI persister cells as compared to parental cells. While the cell surface expression of IL6R was not significantly increased in EGFR-TKI persister cells as compared to parental cells, we observed increased secretion of soluble IL6R in persister cells by ELISA assay. We next assessed changes in protein expression and activation in drug tolerant persister cells by reverse phase protein array (RPPA) and observed that p-STAT3, a key component of the IL-6 signaling pathway, was significantly elevated in persister cells as compared parental cells or cells treated with osimertinib for 24 hours. Using genetically engineered mouse models (GEMM) of EGFRL858R mutant lung cancer, we also observed a similar upregulation of both IL-6 and p-STAT3 expression at the RNA and protein levels in EGFR-mutant tumors treated with osimertinib for 2 or 4 weeks. Additionally, circulating levels of IL-6 also are elevated in EGFRL858R GEMMs treated with osimertinib for 2 or 4 weeks. Collectively, our data indicates that upregulation of IL-6 is an early event in the evolution of drug resistance. Given the role of IL-6 in promoting EGFR TKI resistance, further studies investigating whether targeting of IL-6 signaling may impair the survival or outgrowth of persister populations are warranted. Citation Format: Sonia A. Patel, Monique Nilsson, Yan Yang, Li Shen, Jing Wang, Alissa Poteete, Xiaoxing Yu, Xiaoyang Ren, Xiuning Le, John Heymach. Targeting IL-6/STAT3 signaling in EGFR-mutant drug tolerant persister cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3864.

Brief Report: Durvalumab After Chemoradiotherapy in Unresectable Stage III EGFR-Mutant NSCLC: A Post Hoc Subgroup Analysis From PACIFIC

IntroductionConsolidation durvalumab (the “PACIFIC regimen”) is standard of care for patients with unresectable stage III NSCLC who have not progressed after chemoradiotherapy, on the basis of data from the phase 3 placebo-controlled PACIFIC study (NCT02125461). Nevertheless, the benefit of immunotherapy in patients with stage III EGFR-mutant (EGFRm) NSCLC is not well characterized. Here, we report a post hoc exploratory efficacy and safety analysis from a subgroup of patients with EGFRm NSCLC from the PACIFIC. MethodsPatients with stage III unresectable NSCLC and no progression after more than or equal to two cycles of platinum-based concurrent chemoradiotherapy were randomized (2:1) to receive durvalumab (10 mg/kg intravenously every 2 weeks [wk], for up to 1 y) or placebo; stratified by age, sex, and smoking history. Enrollment was not restricted by oncogenic driver gene mutation status or programmed death-ligand 1 expression. Patients with NSCLC with an EGFR mutation, determined by local testing only, were included in this subgroup analysis. The primary end points were progression-free survival (PFS; assessed by blinded independent central review) and overall survival (OS). Secondary end points included objective response rate and safety. Statistical analyses for the subgroup of patients with EGFRm NSCLC were post hoc and considered exploratory. ResultsOf 713 patients randomized, 35 had locally confirmed EGFRm NSCLC (durvalumab, n = 24; placebo, n = 11). At data cutoff (January 11, 2021), median duration of follow-up for survival was 42.7 months (range: 3.7–74.3 mo) for all randomized patients in the subgroup. Median PFS was 11.2 months (95% confidence interval [CI]: 7.3–20.7) with durvalumab versus 10.9 months (95% CI: 1.9–not evaluable [NE]) with placebo; hazard ratio = 0.91 (95% CI: 0.39–2.13). Median OS was 46.8 months (95% CI: 29.9–NE) with durvalumab versus 43.0 months (95% CI: 14.9–NE) with placebo; hazard ratio = 1.02 (95% CI: 0.39–2.63). The safety profile of durvalumab was generally consistent with the overall population and known profile for durvalumab. ConclusionsPFS and OS outcomes with durvalumab were similar to placebo for patients with EGFRm tumors, with wide CIs. These data should be interpreted with caution owing to small patient numbers and lack of a prospective study that evaluates clinical outcomes by tumor biomarker status. Further research to determine the optimal treatment for unresectable stage III EGFRm NSCLC is warranted.

Targeting tumor-associated macrophages with STING agonism improves the antitumor efficacy of osimertinib in a mouse model of EGFR-mutant lung cancer.

Despite the impressive clinical response rate of osimertinib, a third-generation EGFR-TKI, as a frontline treatment for patients with EGFR-mutant non-small-cell lung cancer (NSCLC) or as a salvage therapy for patients with T790M mutation, resistance to osimertinib is common in the clinic. The mechanisms underlying osimertinib resistance are heterogenous. While genetic mutations within EGFR or other cancer driver pathways mediated mechanisms are well-documented, the role of tumor cell and tumor immune microenvironment in mediating the response to osimertinib remains elusive. Here, using a syngeneic mouse model of EGFR-mutant lung cancer, we show that tumor regression elicited by osimertinib requires activation of CD8+ T cells. However, tumor-associated macrophages (TAMs) accumulated in advanced tumors inhibit CD8+ T cell activation and diminish the response to osimertinib. These results are corroborated by analyses of clinical data. Notably, reprogramming TAMs with a systemic STING agonist MSA-2 reinvigorates antitumor immunity and leads to durable tumor regression in mice when combined with osimertinib. Our results reveal a new mechanism of EGFR-TKI resistance and suggest a new therapeutic strategy for the treatment of EGFR-mutant tumors.

PD-1 blockade augments CD8+ T cell dependent antitumor immunity triggered by Ad-SGE-REIC in Egfr-mutant lung cancer

ObjectivesNo immunotherapeutic protocol has yet been established in never-smoking patients with lung cancer harboring driver oncogenic mutations, such as epidermal growth factor receptor (EGFR) mutations. The immunostimulatory effect of Ad-REIC, a genetically engineered adenovirus vector expressing a tumor suppressor gene, reduced expression in immortalized cells (REIC), has been investigated in clinical trials for various solid tumors. However, the immunostimulatory effect of the Ad-REIC in EGFR-mutant lung cancer with a non-inflamed tumor microenvironment (TME) has not been explored. Materials and methodsWe used a syngeneic mouse model developed by transplanting Egfr-mutant lung cancer cells into single or double flanks of C57BL/6J mice. Ad-SGE-REIC, a 2nd-generation vector with an enhancer sequence, was injected only into the tumors from one flank, and its antitumor effects were assessed. Tumor-infiltrating cells were evaluated using immunohistochemistry or flow cytometry. The synergistic effects of Ad-SGE-REIC and PD-1 blockade were also examined. ResultsInjection of Ad-SGE-REIC into one side of the tumor induced not only a local antitumor effect but also a bystander abscopal effect in the non-injected tumor, located on the other flank. The number of PD-1+CD8+ T cells increased in both injected and non-injected tumors. PD-1 blockade augmented the local and abscopal antitumor effects of Ad-SGE-REIC by increasing the number of CD8+ T cells in the TME of Egfr-mutant tumors. Depletion of CD8+ cells reverted the antitumor effect, suggesting they contribute to antitumor immunity. ConclusionAd-SGE-REIC induced systemic antitumor immunity by modifying the TME status from non-inflamed to inflamed, with infiltration of CD8+ T cells. Additionally, in Egfr-mutant lung cancer, this effect was enhanced by PD-1 blockade. These findings pave the way to establish a novel combined immunotherapy strategy with Ad-SGE-REIC and anti-PD-1 antibody for lung cancer with a non-inflamed TME.

IL6 Mediates Suppression of T- and NK-cell Function in EMT-associated TKI-resistant EGFR-mutant NSCLC.

Patients with advanced non-small cell lung cancer (NSCLC) harboring activating EGFR mutations are initially responsive to tyrosine kinase inhibitors (TKI). However, therapeutic resistance eventually emerges, often via secondary EGFR mutations or EGFR-independent mechanisms such as epithelial-to-mesenchymal transition. Treatment options after EGFR-TKI resistance are limited as anti-PD-1/PD-L1 inhibitors typically display minimal benefit. Given that IL6 is associated with worse outcomes in patients with NSCLC, we investigate whether IL6 in part contributes to this immunosuppressed phenotype. We utilized a syngeneic genetically engineered mouse model (GEMM) of EGFR-mutant NSCLC to investigate the effects of IL6 on the tumor microenvironment and the combined efficacy of IL6 inhibition and anti-PD-1 therapy. Corresponding in vitro studies used EGFR-mutant human cell lines and clinical specimens. We identified that EGFR-mutant tumors which have oncogene-independent acquired resistance to EGFR-TKIs were more mesenchymal and had markedly enhanced IL6 secretion. In EGFR-mutant GEMMs, IL6 depletion enhanced activation of infiltrating natural killer (NK)- and T-cell subpopulations and decreased immunosuppressive regulatory T and Th17 cell populations. Inhibition of IL6 increased NK- and T cell-mediated killing of human osimertinib-resistant EGFR-mutant NSCLC tumor cells in cell culture. IL6 blockade sensitized EGFR-mutant GEMM tumors to PD-1 inhibitors through an increase in tumor-infiltrating IFNγ+ CD8+ T cells. These data indicate that IL6 is upregulated in EGFR-mutant NSCLC tumors with acquired EGFR-TKI resistance and suppressed T- and NK-cell function. IL6 blockade enhanced antitumor immunity and efficacy of anti-PD-1 therapy warranting future clinical combinatorial investigations.

Chronic Inhalation Exposure to Antimony Trioxide Exacerbates the MAPK Signaling in Alveolar Bronchiolar Carcinomas in B6C3F1/N Mice.

Antimony trioxide (AT) is used as a flame retardant in fabrics and plastics. Occupational exposure in miners and smelters is mainly through inhalation and dermal contact. Chronic inhalation exposure to AT particulates in B6C3F1/N mice and Wistar Han rats resulted in increased incidences and tumor multiplicities of alveolar/bronchiolar carcinomas (ABCs). In this study, we demonstrated Kras (43%) and Egfr (46%) hotspot mutations in mouse lung tumors (n = 80) and only Egfr (50%) mutations in rat lung tumors (n = 26). Interestingly, there were no differences in the incidences of these mutations in ABCs from rats and mice at exposure concentrations that did and did not exceed the pulmonary overload threshold. There was increased expression of p44/42 mitogen-activated protein kinase (MAPK) (Erk1/2) protein in ABCs harboring mutations in Kras and/or Egfr, confirming the activation of MAPK signaling. Transcriptomic analysis indicated significant alterations in MAPK signaling such as ephrin receptor signaling and signaling by Rho-family GTPases in AT-exposed ABCs. In addition, there was significant overlap between transcriptomic data from mouse ABCs due to AT exposure and human pulmonary adenocarcinoma data. Collectively, these data suggest chronic AT exposure exacerbates MAPK signaling in ABCs and, thus, may be translationally relevant to human lung cancers.

EGFR-Tyrosine Kinase Inhibitors Induced Activation of the Autocrine CXCL10/CXCR3 Pathway through Crosstalk between the Tumor and the Microenvironment in EGFR-Mutant Lung Cancer

CXCL10 is a cytokine that is elevated during EGFR-TKI treatment in the tumor microenvironment of lung cancer. Here, we report an original study that the impact of the CXCL10/CXCR3 pathway on EGFR-TKI resistance in EGFR-mutant lung cancer through a cytokine array analysis during in vitro coculture with tumor cells and activated PBMCs treated with EGFR-TKI, as well as the serial analysis of CXCL10 in EGFR-mutant lung cancer transgenic mice during EGFR-TKI treatment. In EGFR-mutant tumor cells cocultured with activated PBMCs, EGFR-TKI treatment increased CXCL10 in the supernatant; this activated CXCR3 in the tumor cells to induce the phosphorylation of Src and the NF-κB subunit, p65, and the expression of HIF-1α. CXCL10 siRNA treatment of EGFR-mutant tumor cells also decreased CXCL10 in the supernatant from coculturing with activated PBMCs, suggesting that the effects of CXCL10 occur via autocrine and paracrine pathways. Importantly, elevated CXCL10/CXCR3 signaling was recapitulated in a transgenic lung cancer mouse model. Our results show that increased CXCL10 levels during early EGFR-TKI treatment stimulate oncogenic signaling of persistent tumor cells to contribute to EGFR-TKI resistance via autocrine and paracrine pathways.

Tumor PKCδ instigates immune exclusion in EGFR-mutated non-small cell lung cancer.

The recruitment of a sufficient number of immune cells to induce an inflamed tumor microenvironment (TME) is a prerequisite for effective response to cancer immunotherapy. The immunological phenotypes in the TME of EGFR-mutated lung cancer were characterized as non-inflamed, for which immunotherapy is largely ineffective. Global proteomic and phosphoproteomic data from lung cancer tissues were analyzed aiming to map proteins related to non-inflamed TME. The ex vivo and in vivo studies were carried out to evaluate the anti-tumor effect. Proteomics was applied to identify the potential target and signaling pathways. CRISPR-Cas9 was used to knock out target genes. The changes of immune cells were monitored by flow cytometry. The correlation between PKCδ and PD-L1 was verified by clinical samples. We proposed that PKCδ, a gatekeeper of immune homeostasis with kinase activity, is responsible for the un-inflamed phenotype in EGFR-mutated lung tumors. It promotes tumor progression by stimulating extracellular matrix (ECM) and PD-L1 expression which leads to immune exclusion and assists cancer cell escape from T cell surveillance. Ablation of PKCδ enhances the intratumoral penetration of T cells and suppresses the growth of tumors. Furthermore, blocking PKCδ significantly sensitizes the tumor to immune checkpoint blockade (ICB) therapy (αPD-1) in vitro and in vivo model. These findings revealed that PKCδ is a critical switch to induce inflamed tumors and consequently enhances the efficacy of ICB therapy in EGFR-mutated lung cancer. This opens a new avenue for applying immunotherapy against recalcitrant tumors.

Notch pathway regulates osimertinib drug-tolerant persistence in EGFR-mutated non-small-cell lung cancer.

Osimertinib is a third-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) that has shown marked antitumor activity in patients with EGFR-mutated non-small-cell lung cancer (NSCLC). However, these effects are transient and most patients develop resistance. Reversible drug-tolerant persister (DTP) cells are defined as a small subpopulation of cells with markedly reduced sensitivity and non-genetic acquired resistance to EGFR-TKIs. Notch is a transmembrane receptor that plays an important role in tumorigenesis. We previously reported that there is significant crosstalk between the Notch and EGFR pathways in NSCLC. Moreover, the Notch pathway is associated with resistance to previous-generation EGFR-TKIs. However, the role of Notch in osimertinib resistance is not fully understood. In this study, we evaluated whether Notch is involved in osimertinib resistance. We show that NOTCH1 and Notch target genes are upregulated in osimertinib DTP cells, and that the addition of a γ-secretase inhibitor (GSI), a Notch inhibitor, impairs drug-tolerant persistence in vitro and in vivo. Compared with osimertinib, combined GSI and osimertinib suppress phospho-ERK partly by enhancing DUSP1 expression. Furthermore, Notch1 and HES1 were upregulated after EGFR-TKI treatment in half of human EGFR-mutated NSCLC tumor tissues. These results suggest that the combination of GSI and osimertinib may be a potential therapy for EGFR-mutated NSCLC.

Interleukin-10 induces expression of CD39 on CD8+T cells to potentiate anti-PD1 efficacy in EGFR-mutated non-small cell lung cancer

BackgroundAnti-PD-1(L1) therapies are less efficacious in patients with EGFR-mutated non-small-cell lung cancer. However, the underlying mechanism is poorly understood.MethodsThe characteristics of T cells in EGFR-mutated and wild-type tumors were analyzed...

CSIG-21. EXPLORING THE PHENOTYPIC EFFECTS OF TOLL SIGNALING PATHWAYS IN TUMOR PROGRESSION IN EGFR-DRIVEN GLIOBLASTOMA MODELS

Abstract The treatment options for Glioblastoma (GBM) are currently limited to resection and chemotherapy approaches, but resistance to chemotherapy is common in patients. There is an urgent need for further understanding of the underlying biology of tumorigenesis in order to develop new treatment options. Previous genomic work on GBMs has shown that the epidermal growth factor receptor (EGFR) is frequently amplified and constitutively active in GBM tumors. To discover new factors that contribute to progression of EGFR-driven GBMs, we used our Drosophila GBM model in which GBM-like glial neoplasia can be induced by glial-specific overexpression of constitutively active forms of EGFR and dp110, a subunit of Phosphoinositide 3-kinase (PI3K), using the UAS-GAL4 gene expression system. Using our Drosophila GBM model system, we performed a modifier screen in which we searched for genes and pathways that worsened or ‘enhanced’ glial neoplasia when specifically overexpressed or activated in neoplastic glia. From our screen, we identified the Toll pathway, which in Drosophila activates an NF-κB signaling pathway. Furthermore, the Toll pathway normally functions in innate immune and injury responses as well as in development and cell proliferation. Using our Drosophila GBM model, we are studying how the Toll signaling pathway and its effectors, including NF-κB, contribute to enhanced growth of neoplastic glial cells. Furthermore, using well-defined mouse genetic models and human patient-derived GBM models, we are examining whether Toll pathway regulatory and signaling mechanisms that we have uncovered in Drosophila function in EGFR-mutant GBM tumor stem cells to promote GBM progression and chemotherapy resistance.

High levels of AXL expression in untreated EGFR-mutated non-small cell lung cancer negatively impacts the use of osimertinib.

For non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations, the initial therapeutic interventions will have crucial impacts on their clinical outcomes. Drug tolerant factors reportedly have an impact on EGFR-tyrosine kinase inhibitor sensitivity. This prospective study investigated the impacts of drug tolerant-related protein expression in tumors based on the efficacy of osimertinib in the first-setting of EGFR-mutated advanced NSCLC patients. A total of 92 patients with EGFR-mutated advanced or postoperative recurrent NSCLC were analyzed and treated with osimertinib at 14 institutions in Japan. AXL, p53, and programmed death-ligand 1 (PD-L1) expression in patient tumors was determined using immunohistochemistry. The AXL signaling pathway was investigated using a cell line-based assay and AXL-related gene expression in The Cancer Genome Atlas (TCGA) database. High levels of AXL and positive-p53 expression were detected in 26.1% and 53.3% of the pretreatment EGFR-mutated NSCLC tumors, respectively. High AXL expression levels were significantly associated with a shorter progression-free survival compared with low AXL expression levels, irrespective of the EGFR activating mutation status (p= 0.026). Cell line-based assays indicated that the overexpression of AXL protein accelerated PD-L1 expression, which induced insensitivity to osimertinib. In the TCGA database, AXL RNA levels were positively correlated with PD-L1 expression in the lung adenocarcinoma cohort. The results show that high AXL expression levels in tumors impact clinical predictions when using osimertinib to treat EGFR-mutated NSCLC patients. Trial Registration: UMIN000043942.

235 (PB115) - Phase II trial of afatinib in patients with EGFR-mutated solid tumors excluding lung cancer: results from the NCI-MATCH ECOG-ACRIN Trial (EAY131) Subprotocol A

Background: Molecularly targeted treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have prolonged survival of pts with activating EGFR mutations in non-small cell lung cancer (NSCLC). Afatinib is an ErbB family blocker that demonstrated clinical benefit in pts with NSCLC with common and uncommon activating EGFR mutations. The activity of afatinib in other tumor types with EGFR mutations is less well known. National Cancer Institute-Molecular Analysis for Therapy Choice (NCI-MATCH) Arm EAY131-A evaluated afatinib in tumors beyond lung cancer that harbored EGFR activating alterations.

111 (PB101) - IK930, a novel TEAD inhibitor, sensitizes KRAS and EGFR mutant tumors to oncogene targeted therapy

The Hippo signaling pathway plays a key role in the regulation of cell proliferation, survival, and tissue homeostasis. The transcription co-factors YAP and TAZ, the downstream effectors of this pathway, are phosphorylated by the LATS1/2 kinases in response to a signaling cascade initiated by the MST1/2 (Hippo) kinases. Upon phosphorylation, YAP/TAZ can be sequestered in the cytoplasm or targeted for degradation. In the absence of phosphorylation, YAP and TAZ translocate to the cell nucleus where they interact with members of the TEAD transcription factor family to activate target gene expression.

Clinical and Genomic Features of HER2 Exon 20 Insertion Mutations and Characterization of HER2 Expression by Immunohistochemistry in East Asian Non-Small-Cell Lung Cancer.

HER2-altered non-small-cell lung cancer (NSCLC) represents a diverse subgroup, including mutations, amplifications, and overexpression. However, HER2 exon 20 insertion mutations are emerging as a distinct molecular subtype with expanding therapeutic options. We describe the molecular epidemiology and genomic features of HER2-altered NSCLC in an Asian tertiary cancer center. We identified patients with HER2-mutated NSCLC in our institutional database, collating clinicopathological features and treatment outcomes. The genomic landscape of human epidermal growth factor receptor 2 (HER2)-mutated NSCLC was further evaluated using whole-exome sequencing (WES) data from combined local and publicly available data sets. HER2 amplification and overexpression as selection biomarkers in NSCLC were further interrogated using HER2 immunohistochemistry and correlations with WES and RNA sequencing data. Among 1,252 patients with consecutive lung adenocarcinoma undergoing routine next-generation sequencing, the prevalence of HER2 mutations was 3.1%-exon 20 insertion mutations comprised 2.7%. We examined the clinicopathological features in 55 patients with HER2-mutated NSCLC comprising 40 exon 20 insertion and 15 nonexon 20 insertion mutations. The most common exon 20 insertion mutation was HER2Y772_A775dup in 30 (75%), followed by HER2G776delinsVC in five patients (13%). There were limited responses to HER2-directed therapies apart from trastuzumab-deruxtecan, and no responses were seen with immunotherapy monotherapy. Evaluating the genomics features of HER2 exon 20 insertion mutations using WES data revealed low tumor mutational burden (TMB), low incidence of cancer driver comutations, and a predominance of aging mutational signature-similar to EGFR-mutated tumors. In contrast, uncommon (or nonexon 20 insertion) HER2-mutated tumors resembled EGFR wild-type tumors with higher TMB, higher frequency of cancer driver comutations, and greater presence of smoking and APOBEC mutational signature. Finally, in evaluating HER2 immunohistochemistry in all lung adenocarcinoma, there was significant discordance comparing different scoring systems and poor correlation with HER2 RNA expression and HER2 amplification. The incidence of HER2 mutations is 3.1% in East Asian nonsquamous NSCLC. HER2 exon 20 insertion-mutated tumors appear genomically distinct from uncommon (nonexon 20 insertion) HER2 mutations, the latter demonstrating higher TMB, co-occurring drivers, and predominant nonaging mutational signature. The therapeutic implications of the genomic and clinical features of HER2-mutated NSCLC warrant further investigation.

Dynamic Assessment of Tissue and Plasma EGFR-Activating and T790M Mutations with Droplet Digital PCR Assays for Monitoring Response and Resistance in Non-Small Cell Lung Cancers Treated with EGFR-TKIs.

Assessing tumor EGFR mutation status is necessary for the proper management of patients with advanced non–small cell lung cancer (NSCLC). We evaluated the impact of dynamic analyses of the plasma and tissue EGFR mutation using ultra-sensitive droplet digital PCR (ddPCR) assays to manage NSCLC patients treated with EGFR tyrosine kinase inhibitors (EGFR-TKIs). Paired tumor tissues and plasma samples from 137 EGFR-mutated lung adenocarcinoma patients prior to the first-line EGFR-TKIs treatment (at baseline) and at disease progression were subjected to EGFR mutation analysis using ddPCR, together with the analyses of the clinicopathological characteristics and treatment outcomes. Patients with EGFR-activating mutations detected in baseline plasma were associated with bone metastasis (p = 0.002) and had shorter progression-free survival (12.9 vs. 17.7 months, p = 0.02) and overall survival (24.0 vs. 39.4 months, p = 0.02) compared to those without. Pre-treatment EGFR T790M mutation found in baseline tumor tissues of 28 patients (20.4%; 28/137) was significantly associated with brain metastasis (p = 0.005) and a shorter brain metastasis-free survival (p = 0.001). The presence of EGFR T790M mutations in baseline tumor tissues did not correlate with the emergence of acquired EGFR T790M mutations detected at progression. At disease progression, acquired EGFR T790M mutations were detected in 26.6% (21/79) of the plasma samples and 42.9% (15/35) of the rebiopsy tissues, with a concordance rate of 71.4% (25/35). The dynamic monitoring of tissue and plasma EGFR mutation status at baseline and progression using ddPCR has a clinical impact on the evaluation of EGFR-TKIs treatment efficacy and patient outcomes, as well as the emergence of resistance in NSCLC.