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Approximately 15% of all patients with non-small cell lung cancer (NSCLC) and nearly 35% of Asian patients with NSCLC harbor activating mutations within the epidermal growth factor receptor (EGFR). Although these patients are initially highly sensitive to first or second generation EGFR tyrosine kinase inhibitors (TKIs) including erlotinib or third-generation inhibitors including osimertinib, EGFR TKI-refractory disease inevitably emerges. While therapeutic strategies to target resistant disease that emerges though secondary EGFR mutations or MET amplification have been developed, there remains a void of therapeutic options for patients where resistance occurs through EGFR-independent mechanism such as epithelial to mesenchymal transition (EMT) or transformation to small cell lung cancer (SCLC). To identify cell surface proteins that could be targeted by antibody-based or adoptive cell therapy approaches we interrogated RNAseq data from EGFR mutant NSCLC cell lines (HCC827 and HCC4006) and their associated EGFR TKI resistant variants previously shown to have developed resistance through EMT and filtered gene expression data to include only genes which transcribed proteins localized to the cell surface. We identified CD70 as a being highly upregulated in EGFR TKI resistant cells (p = 7.2e-42). Given that CD70 expression is highly restricted and only transiently expressed on immune cells, CD70 was selected as a top candidate cell surface protein for targeting studies. Western blotting and flow cytometry analysis confirmed CD70 protein levels to be highly upregulated in EGFR TKI resistant cells that had undergone EMT but not in cells harboring secondary EGFR mutations or MET amplifications. We also observed CD70 upregulation in osimertinib-treated drug tolerant persister cells, indicating that CD70 upregulation is an early event in the evolution of TKI resistance. Moreover, patient-derived models of acquired EGFR TKI resistance also exhibited CD70 positivity. Our data also indicated that in EGFR mutant NSCLC cells, CD70 could be upregulated through decreased CD70 promoter methylation as well as by the EMT regulators, transforming growth factor-β (TGF-β) and ZEB1, both of which were upregulated in TKI resistant cells. In EGFR TKI resistant cells, CD70 knockdown impaired cell viability and invasiveness, and stimulation of CD70 using the exogenous binding partner CD27 resulted in activation of AKT and MAPK, pathways known to be re-activated with acquired TKI resistance. CD70-targeting approaches including anti-CD70 antibody drug conjugates (ADCs) and CD70-targeting CAR T cell and CAR NK cells showed promising in vitro and in vivo activity against CD70 positive tumor cells and in osimertinib drug-tolerant persister cells. These results identify CD70 as a novel therapeutic target for EGFR mutant tumors with acquired EGFR TKI resistance that merits further investigation in the clinic. Citation Format: Monique B. Nilsson, Yan Yang, Sonia Patel, Simon Heeke, Xiuning Le, Thiru Aruguman, Jacqulyne Robichaux, Xiaoxing Yu, Alissa Poteete, Xiaoyang Ren, Lixia Diao, Li Shen, Qi Wang, Fahao Zhang, Leticia Campos Clemente, Luisa Solis Soto, Chunhua Shi, Hai Tran, Jason Bock, Jing Wang, Ignacio I. Wistuba, John D. Minna, John V. Heymach. CD70 is a novel therapeutic target for EGFR mutant NSCLC with acquired, EMT-associated EGFR TKI resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1827.

Around 10-15% of non-small cell lung cancer (NSCLC) cases in the United States harbor an activating mutation in epidermal growth factor receptor (EGFR) which are initially highly sensitive to treatment EGFR tyrosine kinase inhibitors (TKI) before eventually developing resistance to these agents. Therefore, there is a current unmet clinical need to identify novel treatment options for this patent population. While anti-PD-1/PD-L1 immunotherapy has been effective for many NSCLC patients, EGFR-mutant tumors have response rates of less than 10%. The mechanisms driving resistance to immunotherapy in EGFR-mutant NSCLC are not well understood. We previously reported that IL-6 is highly upregulated in NSCLC cells with acquired resistance to EGFR-TKIs. Because IL-6 is a pleiotropic cytokine known to impact immune populations within the tumor microenvironment, we hypothesized that IL-6 may drive immunosuppression in EGFR mutant NSCLC. Using genetically engineered mouse models (GEMMs) of EGFR-mutant NSCLC with and without IL-6 knockout, we evaluated the effects of IL-6 on the tumor microenvironment. EGFR-mutant mice with knockout of IL-6 had a significantly increased overall survival compared to those with intact-IL-6. Knockout of IL-6 increased total immune infiltration in these tumors as assessed by flow cytometry. Infiltrating T cells from IL-6 knockout mice displayed a smaller population of T helper 17 cells compared to IL-6-expressing tumors. Knockout of IL-6 also increased the population of infiltrating activated CD8 T cells and a reduced T-regulatory cell population. Due to these changes in T cell activity, we wanted to determine any potential synergistic effects of IL-6 blockade used during anti-PD-1 therapy. We observed that combination treatment extended survival in EGFR-mutant NSCLC mice. Corresponding in vitro T cell cytotoxicity assays confirmed that EGFR-TKI resistant cells treated with IL-6 blocking antibody were more sensitive to T cell-mediated killing. Furthermore, infiltration of NK cells was increased in tumors with knockout of IL-6. Infiltrating NK cells found in these IL-6 knockout mice displayed a more activated phenotype as demonstrated by increased expression of NKG2D. Next, we evaluated the effects of IL-6 from conditioned media collected from human EGFR-mutant and TKI-resistant cells lines on human T and NK cells cultured ex vivo. e determined that IL-6 suppressed expression of activation markers including granzyme B and IFN-y on the surface of both T and NK cells. Blockade of IL-6 increased NK-mediated cytotoxic killing of EGFR-TKI resistant cells in vitro. In conclusion, our data indicates that in EGFR-TKI resistance, upregulated IL-6 suppresses T and NK cell cytotoxic potential and drives immunosuppression. Citation Format: Sonia Patel, Monique Nilsson, Yan Yang, Xiaoxing Yu, Fahao Zhang, Alissa Poteete, Xiaoyang Ren, Li Shen, Jing Wang, Xiuning Le, John Heymach. IL-6 contributes to the suppression of T and NK cell anti-tumor activity in EGFR-mutant NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3125.

Chemotherapies are often impeded by drug resistance of cancer cells, high non-specific toxicity and low selectivity and efficacy of drug delivery. We developed a platform for the selective, fast, guided intracellular delivery of drugs into cancer cells with new cell-specific agents, plasmonic nanobubbles (PNBs). PNBs are not particles but transient events, vapor nanobubbles, induced by a short laser pulse around gold nanoparticles. Therapeutic effects of PNBs have a localized mechanical, non-thermal, nature and can be dynamically tuned in cancer cells to support non-invasive imaging, disruption of endosomes and drug carriers, injection of drug and mechanical cell ablation with single cell selectivity in a heterogeneous tissue. Simultaneous treatment of a bulk tissue activates those functions only in cancer cells while leaving adjacent normal cells intact. Optical and acoustical properties of PNBs provide a real time guidance of therapeutic effect. PNB mechanisms were evaluated for intracellular delivery of free and encapsulated doxorubicin into drug-resistant oral cavity squamous cell carcinoma (OCSCC) cells mixed in a co-culture with normal cells. Gold nanoshells were conjugated with Panitumumab antibody to target EGFR that is overexpressed by OCSCC. Receptor-endocytotic targeting resulted in cancer cell-specific clusters of nanoshells. These clusters selectively generated PNBs only in cancer cells while normal cells did not produce PNBs under simultaneous treatment with a single, short near-infrared laser pulse of low, biologically safe, energy. PNBs selectively delivered free extracellular drug only to cancer cells by creating transient nano-holes in cellular membranes and inbound nanojets that brought the extracellular drug into the cytoplasm. Thus PNBs worked as nano-injector of extracellular drug. Compared to a standard treatment with doxorubicin alone, PNB injection improved therapeutic efficacy by 12-fold and at the same time reduced drug dose by 10-fold and non-specific toxicity by 3-fold. Plasmonic nanobubble-enhanced endosomal escape (PNBEE) provided intracellular delivery of the liposome-encapsulated drug, Doxil, that was administered separately with gold nanoshells through a self-assembly of mixed nanoshell-Doxil nanoclusters by cancer cells. Small PNBs generated in these nanoclusters disrupted both liposomes and endosomes and ejected the released doxorubicin into cytoplasm. Cancer cell-specific generation of PNBs in a mixed co-culture of OCSCC and normal cells increased the therapeutic efficacy of Doxil by 31-fold and at the same time reduced drug dose by 20-fold, treatment time by 3-fold and non-specific toxicity by 10-fold. The described mechanisms of nano-injection and PNBEE are universal, can be applied to various cancers and provide a guided intracellular drug delivery in heterogeneous tissues through the application of plasmonic nanobubbles. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5693. doi:1538-7445.AM2012-5693

The purpose of this study is to determine the optimal timing of treatment for a novel chemoprevention approach in a mouse model of Familial Adenomatous Polyposis (FAP). FAP is an autosomal dominantly inherited disorder caused by mutations in the tumor suppressor Apc (adenomatous polyposis coli) gene, which results in the formation of hundreds to thousands of polyps, predominantly in the colon and rectum. Left untreated, these polyps will form colorectal adenocarcinomas. Although surgical removal of the colon eliminates the colon cancer risk, these individuals are also at increased risk for other primary cancers, including tumors of the small intestine and stomach. Systemic chemopreventive interventions to specifically remove the pre-cancerous cells in these individuals could greatly improve their outcomes and quality of life. Recently, we have developed a new method based on the ability of combined retinoid and TRAIL (tumor necrosis factor related apoptosis inducing ligand) treatment to induce apoptosis and regression of intestinal polyps in ApcMin/+ mice, a mouse model of FAP. Treatment of these mice with retinoid causes an increase in TRAIL death receptors DR4 and DR5 as well as a concomitant decrease in the decoy receptors. APC deficiency leads to a decreased level of the anti-apoptotic protein FLIP (flice-like inhibitory protein). Thus, the combination of TRAIL and retinoid specifically targets APC deficient cells for apoptosis. Following up on these findings, we have tested the hypothesis that early stage adenomas of the intestine will respond more readily to TRAIL and retinoid treatment than those at a later stage. We used ApcMin/+ mice at either two months of age or five-six months of age. Each group of mice was given three treatments of retinyl acetate and TRAIL within one week. Following the last treatment, the intestine was harvested from each mouse and the polyps were counted. The number of polyps in each group of mice was compared with the polyp number in age matched non-treated mice. Results: When treated at two months of age, ApcMin/+ exhibit a nearly 50% decrease in polyp number following only one week of therapy. Conversely, ApcMin/+ treated at five-six months of age did not show any significant difference in polyp number compared to non-treated mice. Conclusion: Earlier stage adenomas respond more readily to the combined treatment of retinoid and TRAIL. This is likely due to additional mutations acquired by the later stage polyps. The cause of this resistance is a current area of study. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1008. doi:1538-7445.AM2012-1008