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Dive into the research topics where Leila Williams is active.

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Featured researches published by Leila Williams.


Cancer Discovery | 2016

Loss of PTEN promotes resistance to T cell–mediated immunotherapy

Weiyi Peng; Jie Qing Chen; Chengwen Liu; Shruti Malu; Caitlin Creasy; Michael T. Tetzlaff; Chunyu Xu; Jodi A. McKenzie; Chunlei Zhang; Xiaoxuan Liang; Leila Williams; Wanleng Deng; Guo Chen; Rina M. Mbofung; Alexander J. Lazar; Carlos A. Torres-Cabala; Zachary A. Cooper; Pei-Ling Chen; Trang Tieu; Stefani Spranger; Xiaoxing Yu; Chantale Bernatchez; Marie-Andree Forget; Cara Haymaker; Rodabe N. Amaria; Jennifer L. McQuade; Isabella C. Glitza; Tina Cascone; Haiyan S. Li; Lawrence N. Kwong

UNLABELLED T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. We show that loss of PTEN in tumor cells in preclinical models of melanoma inhibits T cell-mediated tumor killing and decreases T-cell trafficking into tumors. In patients, PTEN loss correlates with decreased T-cell infiltration at tumor sites, reduced likelihood of successful T-cell expansion from resected tumors, and inferior outcomes with PD-1 inhibitor therapy. PTEN loss in tumor cells increased the expression of immunosuppressive cytokines, resulting in decreased T-cell infiltration in tumors, and inhibited autophagy, which decreased T cell-mediated cell death. Treatment with a selective PI3Kβ inhibitor improved the efficacy of both anti-PD-1 and anti-CTLA-4 antibodies in murine models. Together, these findings demonstrate that PTEN loss promotes immune resistance and support the rationale to explore combinations of immunotherapies and PI3K-AKT pathway inhibitors. SIGNIFICANCE This study adds to the growing evidence that oncogenic pathways in tumors can promote resistance to the antitumor immune response. As PTEN loss and PI3K-AKT pathway activation occur in multiple tumor types, the results support the rationale to further evaluate combinatorial strategies targeting the PI3K-AKT pathway to increase the efficacy of immunotherapy.


Journal of the National Cancer Institute | 2018

The Effect of Topoisomerase I Inhibitors on the Efficacy of T-Cell-Based Cancer Immunotherapy

Jodi A. McKenzie; Rina M. Mbofung; Shruti Malu; Min Zhang; Emily Ashkin; Seram Devi; Leila Williams; Trang Tieu; Weiyi Peng; Sunila Pradeep; Chunyu Xu; Soraya Zorro Manrique; Chengwen Liu; Lu Huang; Yuan Chen; Marie-Andree Forget; Cara Haymaker; Chantale Bernatchez; Nikunj Satani; Florian Muller; Jason Roszik; Ashish Kalra; Timothy P. Heffernan; Anil K. Sood; Jianhua Hu; Rodabe N. Amaria; R. Eric Davis; Patrick Hwu

Abstract Background Immunotherapy has increasingly become a staple in cancer treatment. However, substantial limitations in the durability of response highlight the need for more rational therapeutic combinations. The aim of this study is to investigate how to make tumor cells more sensitive to T-cell-based cancer immunotherapy. Methods Two pairs of melanoma patient-derived tumor cell lines and their autologous tumor-infiltrating lymphocytes were utilized in a high-throughput screen of 850 compounds to identify bioactive agents that could be used in combinatorial strategies to improve T-cell-mediated killing of tumor cells. RNAi, overexpression, and gene expression analyses were utilized to identify the mechanism underlying the effect of Topoisomerase I (Top1) inhibitors on T-cell-mediated killing. Using a syngeneic mouse model (n = 5 per group), the antitumor efficacy of the combination of a clinically relevant Top1 inhibitor, liposomal irinotecan (MM-398), with immune checkpoint inhibitors was also assessed. All statistical tests were two-sided. Results We found that Top1 inhibitors increased the sensitivity of patient-derived melanoma cell lines (n = 7) to T-cell-mediated cytotoxicity (P < .001, Dunnett’s test). This enhancement is mediated by TP53INP1, whose overexpression increased the susceptibility of melanoma cell lines to T-cell cytotoxicity (2549 cell line: P = .009, unpaired t test), whereas its knockdown impeded T-cell killing of Top1 inhibitor–treated melanoma cells (2549 cell line: P < .001, unpaired t test). In vivo, greater tumor control was achieved with MM-398 in combination with α-PD-L1 or α-PD1 (P < .001, Tukey’s test). Prolonged survival was also observed in tumor-bearing mice treated with MM-398 in combination with α-PD-L1 (P = .002, log-rank test) or α-PD1 (P = .008, log-rank test). Conclusions We demonstrated that Top1 inhibitors can improve the antitumor efficacy of cancer immunotherapy, thus providing the basis for developing novel strategies using Top1 inhibitors to augment the efficacy of immunotherapy.


Clinical Cancer Research | 2018

The RNA-binding Protein MEX3B Mediates Resistance to Cancer Immunotherapy by Downregulating HLA-A Expression

Lu Huang; Shruti Malu; Jodi A. McKenzie; Miles C. Andrews; Amjad H. Talukder; Trang Tieu; Tatiana Karpinets; Cara Haymaker; Marie-Andree Forget; Leila Williams; Zhe Wang; Rina M. Mbofung; Zhiqiang Wang; Richard Eric Davis; Roger S. Lo; Jennifer A. Wargo; Michael A. Davies; Chantale Bernatchez; Timothy P. Heffernan; Rodabe N. Amaria; Anil Korkut; Weiyi Peng; Jason Roszik; Gregory Lizée; Scott E. Woodman; Patrick Hwu

Purpose: Cancer immunotherapy has shown promising clinical outcomes in many patients. However, some patients still fail to respond, and new strategies are needed to overcome resistance. The purpose of this study was to identify novel genes and understand the mechanisms that confer resistance to cancer immunotherapy. Experimental Design: To identify genes mediating resistance to T-cell killing, we performed an open reading frame (ORF) screen of a kinome library to study whether overexpression of a gene in patient-derived melanoma cells could inhibit their susceptibility to killing by autologous tumor-infiltrating lymphocytes (TIL). Results: The RNA-binding protein MEX3B was identified as a top candidate that decreased the susceptibility of melanoma cells to killing by TILs. Further analyses of anti–PD-1–treated melanoma patient tumor samples suggested that higher MEX3B expression is associated with resistance to PD-1 blockade. In addition, significantly decreased levels of IFNγ were secreted from TILs incubated with MEX3B-overexpressing tumor cells. Interestingly, this phenotype was rescued upon overexpression of exogenous HLA-A2. Consistent with this, we observed decreased HLA-A expression in MEX3B-overexpressing tumor cells. Finally, luciferase reporter assays and RNA-binding protein immunoprecipitation assays suggest that this is due to MEX3B binding to the 3′ untranslated region (UTR) of HLA-A to destabilize the mRNA. Conclusions: MEX3B mediates resistance to cancer immunotherapy by binding to the 3′ UTR of HLA-A to destabilize the HLA-A mRNA and thus downregulate HLA-A expression on the surface of tumor cells, thereby making the tumor cells unable to be recognized and killed by T cells. Clin Cancer Res; 24(14); 3366–76. ©2018 AACR. See related commentary by Kalbasi and Ribas, p. 3239


Nature Communications | 2018

RNA editing derived epitopes function as cancer antigens to elicit immune responses

Minying Zhang; Jens Fritsche; Jason Roszik; Leila Williams; Xinxin Peng; Yulun Chiu; Chih-Chiang Tsou; Franziska Hoffgaard; Valentina Goldfinger; Oliver Schoor; Amjad H. Talukder; Marie Andrée Forget; Cara Haymaker; Chantale Bernatchez; Leng Han; Yiu-Huen Tsang; Kathleen Kong; Xiaoyan Xu; Kenneth L. Scott; Harpreet Singh-Jasuja; Greg Lizee; Han Liang; Toni Weinschenk; Gordon B. Mills; Patrick Hwu

In addition to genomic mutations, RNA editing is another major mechanism creating sequence variations in proteins by introducing nucleotide changes in mRNA sequences. Deregulated RNA editing contributes to different types of human diseases, including cancers. Here we report that peptides generated as a consequence of RNA editing are indeed naturally presented by human leukocyte antigen (HLA) molecules. We provide evidence that effector CD8+ T cells specific for edited peptides derived from cyclin I are present in human tumours and attack tumour cells that are presenting these epitopes. We show that subpopulations of cancer patients have increased peptide levels and that levels of edited RNA correlate with peptide copy numbers. These findings demonstrate that RNA editing extends the classes of HLA presented self-antigens and that these antigens can be recognised by the immune system.RNA editing is a biological process that creates sequence variation. Here the authors show that peptides generated as a consequence of RNA editing are naturally presented by human leukocyte antigen (HLA) and serve as antigens to elicit anti-tumour immune responses.


Cancer immunology research | 2016

Abstract B118: Using a high throughput T-cell cytotoxicity assay to develop combination strategies for immunotherapy

Leila Williams; Shruti Malu; Jodi A. McKenzie; Rina M. Mbofung; Jason Roszik; Patrick Hwu

T-cells play a critical role in cancer immunosurveillance and control. As such, there has been a recent emergence of T cell based immunotherapies with durable clinical outcomes. These include the immune checkpoint inhibitors Ipilimumab (anti-CTLA-4) and Nivolumab (anti-PD-1), and adoptive cell therapy, which have conferred clinical response rates of up to 50%. Despite these encouraging outcomes, there is still a large cohort of patients for which these treatments are currently not applicable. They are either inherently resistant to or acquire resistance to immunotherapy. As such, understanding mechanisms of resistance to immune response and ascertaining efficacious therapy combinations is important in overcoming immune-resistance and developing novel treatment regimens. To address this need we performed preliminary screening of about 850 different bioactive compounds (Selleckem) to find candidate drugs that could modulate the sensitivity of tumor cells to T- cell mediated killing, using an established protocol for an in vitro T-cell mediated cytotoxicity screen. We hypothesized that either tumor cells treated with different compounds will increase or decrease their sensitivity to T cell mediated killing, and compounds that increase T cell killing can be used in combination with immunotherapy. Using patient-derived melanoma tumor cells and their autologous tumor infiltrating T cells (TILs), we assessed the increase or decrease of T cell killing of tumor cells following treatment with the test compounds via intracellular detection of active caspase-3 by flow cytometry in a 96-well format. This initial screen identified Heat shock protein 90 (Hsp90), Aurora Kinase and Topoisomerase I inhibitors as enhancers of T cell mediated killing, and studies to understand their mechanisms of action are currently underway. However, as this screening process is very time-intensive, we have increased the efficiency and feasibility of this screen by miniaturizing the workflow. This work highlights the development and initial findings of the screening method that is performed in 384-well plates. This format allows for a larger library of compounds, with a greater drug concentration range, and for more autologous tumor and T-cell pairs to be screened within a shorter time. The miniaturized assay also utilises robotics to streamline and increase output. Additionally, by understanding the signaling pathways and molecular factors that regulate tumor response to T cell mediated killing, we can translate these findings applicable to other cancer. This project aims to discover novel compounds that work synergistically with T-cell mediated tumor cell cytotoxicity, understand their mechanism of action and how the inhibited pathways contribute to resistance to immunotherapy and as a result better inform combination strategies with immunotherapy for clinical use. Citation Format: Leila Williams, Shruti Malu, Jodi McKenzie, Rina Mbofung, Jason Roszik, Patrick Hwu. Using a high throughput T-cell cytotoxicity assay to develop combination strategies for immunotherapy [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B118.


Cancer immunology research | 2016

Abstract B105: HSP90 inhibitor, ganetespib, enhances responses to cancer immunotherapy through increased expression of interferon response genes

Rina M. Mbofung; Jodi A. McKenzie; Shruti Malu; Chengwen Liu; Weiyi Peng; Isere Kuiatse; Leila Williams; Seram Devi; Zhe Wang; Trang Tieu; Tim Heffernan; Richard Eric Davis; Rodabe N. Amaria; Patrick Hwu

Recently, T cell based immunotherapies have moved to the forefront of cancer immunotherapy with the success of Adoptive T cell therapy (ACT) and Immune checkpoint blockade. ACT, where patients are treated with tumor infiltrating T cells (TILs), conferred a clinical response rate of ∼50%. Treatment with anti-CTLA4 therapy, Ipilimumab, conferred response rates of 10-20%, greatly improving the overall survival of patients with advanced melanoma. Despite the encouraging outcomes, there are relatively low response rates coupled with the delay of weeks to months before tumor shrinkage can be appreciated. Thus, understanding mechanisms of resistance to immune therapies, to improve response rates, shorten time to treatment effect and developing predictive biomarkers of response are vital to the care of melanoma patients. In order to identify possible resistance mechanisms to immunotherapy, a high-throughput in vitro screen with 850 different bio-active compounds (Selleckchem), was designed to search for agents that could either increase or decrease the resistance of melanoma tumor cells to T cell mediated killing. Paired patient derived human melanoma tumor samples and TILs were used to assess which compounds when used to treat the melanoma cell lines can enhance the cytotoxic activity of the TILs against the paired melanoma sample, using a flow cytometry based assay in which active caspase 3 was used as a read out of apoptosis. We identified heat shock protein 90 (HSP90) inhibitors amongst the top compounds that improved T cell mediated cytotoxicity of treated tumor cells. We show that treatment with the HSP90 inhibitor ganetespib (Synta) greatly improves T cell mediated cytotoxicity of human cancer cells lines in vitro. Furthermore, in vivo murine studies using the MC38/gp100 tumor model show that ganestespib in combination with anti-CTLA4, resulted in superior antitumor effect and survival compared to either treatment alone (Average tumor volume at day 21 of treatment: Vehicle 294.3mm3, α-CTLA4 193 mm3, Ganetespib 237.5 mm3 and Ganetespib + α-CTLA4 105.8 mm3, P Citation Format: Rina M. Mbofung, Jodi A. McKenzie, Shruti Malu, Chengwen Liu, Weiyi Peng, Isere Kuiatse, Leila Williams, Seram Devi, Zhe Wang, Trang Tieu, Tim Heffernan, Richard E. Davis, Rodabe Amaria, Patrick Hwu. HSP90 inhibitor, ganetespib, enhances responses to cancer immunotherapy through increased expression of interferon response genes [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B105.


Cancer immunology research | 2016

Abstract B110: Topoisomerase I inhibitors enhance efficacy of immunotherapy through a p53 regulatory pathway

Jodi A. McKenzie; Rina M. Mbofung; Shruti Malu; Rodabe N. Amaria; Emily Ashkin; Seram Devi; Weiyi Peng; Leila Williams; Richard Eric Davis; Jason Roszik; Trang Tieu; Timothy P. Heffernan; Patrick Hwu

Cancer immunotherapy has transformed the treatment landscape for a number of cancer patients, with some achieving durable and long lasting clinical benefit. Cancer immunotherapy engages and intensifies the host immune response to attack and kill tumor cells. However, as evidenced by the heterogeneous response to immunotherapy, tumor cells have evolved a host of known and unknown mechanisms to evade, inhibit or supersede the immune response. Consequently, scientists and clinicians are unable to accurately predict which patients will respond, or how well they will respond to cancer immunotherapy.To address this shortfall, we have asked the question of how we can modulate tumor cells in order to make them more amenable to immunotherapy, thereby increasing its efficacy. We approached this question by conducting a high throughput drug screen of 850 compounds, to identify bioactive drugs that can increase T cell mediated killing of tumor cells. The goal here is to develop rational combination treatment strategies involving T cell based cancer immunotherapy that will increase the breadth and depth of the clinical response to cancer immunotherapy. One of three top hits from the screen was Topoisomerase I (Top1) inhibitors including irinotecan, topotecan, and camptothecin. We then utilized multiple patient-derived cell lines in an in vitro cytotoxicity assay to validate that treatment of melanoma tumor cells with a Top1 inhibitor, before incubation with their autologous tumor infiltrating lymphocytes (TILs) results in a synergistic increase in T cell mediated killing of tumor cells.These findings were further corroborated in a pre-clinical mouse model, where we found that tumor-bearing mice treated with a combination of a clinically relevant Top1 inhibitor nal-IRI (nano-liposomal irinotecan) and an anti-PD-L1 antibody, showed enhanced tumor regression compared to mice treated with either single agent (mean tumor volume: combo vs nal-IRI vs α-PDL1 = 40.04 ± 5.66 vs 136.30 ± 28.96 vs 373.04 ± 23.96 mm 3 respectively, on day 21 after tumor inoculation, p TP53INP1 (Teap) . We then focused on the functional relevance of Teap to the increased T cell mediated killing of Top1 inhibitor-treated melanoma cells. Overexpression of Teap in melanoma cells resulted in increased T cell mediated killing, recapitulating the phenotype observed in Top1 inhibitor-treated melanoma cells. Complementary to this, silencing of Teap via shRNA in melanoma cells, inhibited T cell mediated killing of Top1 inhibitor-treated cells, indicating that the enhancement of T cell mediated killing observed in Top1 inhibitor-treated cells is dependent on the p53 regulatory gene Teap . These results support our goal of developing combinations involving T cell based cancer immunotherapy to improve therapeutic efficacy in cancer patients. We have demonstrated that Top1 inhibitors can be effectively combined with T cell based cancer immunotherapy. The results are also indicative of a role for p53 signaling in regulating response to T cell based immunotherapy. By understanding the molecular mechanisms in the tumor that can dictate response or resistance to immunotherapy, we can develop a more comprehensive picture of the cancer immunity response cycle and develop more effective strategies to combat not only melanoma, but also other tumor types where immunotherapy is not yet applicable. Citation Format: Jodi A. McKenzie, Rina M. Mbofung, Shruti Malu, Rodabe N. Amaria, Emily L. Ashkin, Seram N. Devi, Weiyi Peng, Leila J. Williams, Richard E. Davis, Jason Roszik, Trang N. Tieu, Timothy Heffernan, Patrick Hwu. Topoisomerase I inhibitors enhance efficacy of immunotherapy through a p53 regulatory pathway [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B110.


Cancer immunology research | 2016

Abstract IA19: Rational combinations of targeted and immunotherapies

Weiyi Peng; Rina M. Mbofung; Leila Williams; Patrick Hwu

Both targeted therapy and immunotherapy have shown great promise for the treatment of cancer patients, but neither approach results in durable success in the majority of patients. The combination of targeted therapies with immunotherapies has the potential to result in higher, more durable clinical responses and improved survival in patients with metastatic cancer. Besides inducing the release of antigens following tumor destruction, targeted therapies may also reverse the immunosuppressive microenvironment found at the tumor site. In previous studies, we found that BRAF inhibition enhances T-cell infiltration into tumors, partially by downregulating VEGF at the tumor site (CCR, Liu et al 2013). In addition, we have found other combinations in murine models that are effective, such as dasatinib plus anti-OX40 antibody in c-kit positive tumors (Blood, Yang et al 2012). Recently we reported that PTEN loss in tumors results in less infiltration by T-cells, and lower responses to anti-PD1 therapy in advanced melanoma patients (Cancer Discovery, Peng et al 2016). Importantly, this could be overcome in murine models using a combination of PI3K beta inhibitor and anti-PD1, a concept which will be tested in the clinic. We are now utilizing a high throughput screen of more than 1000 compounds to determine which can most effectively enhance the ability of tumor-specific T-cells to kill autologous tumor (poster #341). This screen evaluates tumor death using flow cytometry to detect intratumoral activated caspases 3 and 7, since T-cells kill using a caspase-dependent apoptotic pathway. Positive candidates are then confirmed and tested in murine tumor models. We are also evaluating the molecular basis of immune resistance using a similar in vitro screen as well as an in vivo screen with tumor cells transduced with shRNA libraries. Positive candidates will be tested for expression utilizing our banked samples from responding and non-responding patients who have received tumor-infiltrating lymphocytes (TIL). Using these screens we have thus far determined that the aurora kinase inhibitors, topoisomerase I inhibitors (poster #214), and HSP90 inhibitors (poster #276) enhance T-cell based immunotherapies. We are evaluating the mechanisms of action of these combination therapies. HSP90 inhibitors enhance anti-CTLA4 activity due to a mechanism involving the interferon response genes, for example. We have also found that altering metabolic pathways (eg, inhibiting glycolysis) in tumor cells enhances antitumor immune responses. In summary, we are currently performing high throughput screens to determine the best agents to combine with immunotherapy strategies, as well as molecular determinants of immune resistance. Citation Format: Weiyi Peng, Rina Mbofung, Leila Williams, Patrick Hwu. Rational combinations of targeted and immunotherapies [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr IA19.


Cancer Research | 2016

Abstract 4363: Loss of PTEN promotes resistance to T cell-mediated immunotherapy

Weiyi Peng; Jie Qing Chen; Chengwen Liu; Shruti Malu; Caitlin Creasy; Michael T. Tetzlaff; Chunyu Xu; Jodi A. McKenzie; Chunlei Zhang; Xiaoxuan Liang; Leila Williams; Wanleng Deng; Guo Chen; Rina M. Mbofung; Alexander J. Lazar; Carlos A. Torres-Cabala; Zachary A. Cooper; Pei-Ling Chen; Trang Tieu; Stefani Spranger; Xiaoxing Yu; Chantale Bernatchez; Marie-Andree Forget; Cara Haymaker; Rodabe N. Amaria; Jennifer L. McQuade; Isabella C. Glitza; Tina Cascone; Haiyan Li; Lawrence Kwong

T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. Here, we interrogated the role of loss of expression of the tumor suppressor, PTEN, in immune resistance. In preclinical studies, we found that silencing PTEN in tumor cells inhibited T cell-mediated tumor killing and decreased T cell trafficking into tumors. In clinical studies, we observed that tumors with loss of PTEN had significantly less CD8+ T cell infiltration than PTEN-present tumors. In addition, 26% of melanomas that did not yield successful TIL growth demonstrated PTEN loss, which was more frequent than was observed in tumors that yielded successful TIL growth (11%). We further validated the association between reduced number and impaired function of TIL with PTEN loss using another independent cohort, TCGA dataset for SKCM. More importantly, we analyzed clinical outcomes of metastatic melanoma patients treated with the FDA-approved anti-PD-1 antibodies. Our analysis demonstrates that a greater reduction in tumor burden was achieved by PD-1 blockade in PTEN present patients, when compared with PTEN absent patients. To decipher the factors mediating the immunosuppressive effects of PTEN loss, we determined the expression profiles of tumor cells with or without PTEN expression. Our results indicated that PTEN loss increased the production of immunosuppressive factors, including CCL2 and VEGF. Anti-VEGF blocking antibody improved anti-tumor activity of transferred tumor-reactive T cells and enhanced tumor infiltration of transferred T cells in PTEN-silenced tumors. These results suggest that loss of PTEN can facilitate the resistance of T cell-mediated immune responses by increasing the expression of immunosuppressive factors. Given that PTEN loss results in activation of the PI3K pathway, we evaluated the efficacy of immunotherapy in combination with a selective PI3Kβinhibitor to treat spontaneously developed BRAF mutant, PTEN null melanomas in genetically engineered mouse models. Our result showed that the combination of PI3Kβ inhibitor and anti-PD-1 significantly delayed tumor growth in tumor-bearing mice. Mice treated with this combination had a median survival time of 28 days, which is longer than the survival time of mice treated with either therapy. Increased numbers of T cells at tumor sites were found in mice receiving the combination therapy compared with mice receiving either agent alone. Taken together, our results demonstrate that PTEN loss contributes to the generation of immunosuppressive tumor microenvironment. Notably, this study provides the first direct clinical evidence to support the association between PTEN loss and poor clinical outcome in immunotherapy treated patients. In addition, our study indicates that inhibition of the PI3K-AKT pathway can improve the efficacy of immunotherapy in cancer. Citation Format: Weiyi Peng, Jie Qing Chen, Chengwen Liu, Shruti Malu, Caitlin Creasy, Michael Tetzlaff, Chunyu Xu, Jodi McKenzie, Chunlei Zhang, Xiaoxuan Liang, Leila Williams, Wanleng Deng, Guo Chen, Rina Mbofung, Alexander Lazar, Carlos Torres-Cabala, Zachary Cooper, Pei-Ling Chen, Trang Tieu, Stefani Spranger, Xiaoxing Yu, Chantale Bernatchez, Marie-Andree Forget, Cara Haymaker, Rodabe Amaria, Jennifer McQuade, Isabella Glitza, Tina Cascone, Haiyan Li, Lawrence Kwong, Timothy Heffernan, Jianhua Hu, Roland Bassett, Marcus Bosenberg, Scott Woodman, Willem Overwijk, Gregory Lizee, Jason Roszik, Thomas Gajewski, Jennifer Wargo, Jeffrey Gershenwald, Laszlo Radvanyi, Michael Davies, Patrick Hwu. Loss of PTEN promotes resistance to T cell-mediated immunotherapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4363.


Cancer Research | 2016

Abstract 4360: Inhibition of HSP90 enhances T cell-mediated antitumor immune responses through expression of interferon-alpha response Genes

Rina M. Mbofung; Jodi A. McKenzie; Shruti Malu; Chengwen Liu; Leila Williams; Weiyi Peng; Zhe Wang; Satyendra C. Tripathi; Trang Tieu; Shuping Zhao; Seram Devi; Isere Kuiatse; Emily Ashkin; Leah Bailey; Jason Roszik; Samir M. Hanash; Timothy P. Heffernan; Richard Eric Davis; Rodabe N. Amaria; Patrick Hwu

Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA Recently, T cell based immunotherapies have moved to the forefront of cancer immunotherapy with the success of Adoptive T cell therapy (ACT) and Immune checkpoint blockade. ACT, where patients are treated with tumor infiltrating T cells (TILs), conferred a clinical response rate of ∼50%. Treatment with anti-CTLA4 therapy, Ipilimumab, conferred response rates of 10-20%, greatly improving the overall survival of patients with advanced melanoma. Despite the encouraging outcomes, there are relatively low response rates coupled with the delay of weeks to months before tumor shrinkage can be appreciated. Thus, understanding mechanisms of resistance to immune therapies, to improve response rates, shorten time to treatment effect and developing predictive biomarkers of response are vital to the care of melanoma patients. In order to identify possible resistance mechanisms to immunotherapy, a high-throughput in vitro screen with 850 different bio-active compounds (Selleckchem), was designed to search for agents that could either increase or decrease the resistance of melanoma tumor cells to T cell mediated killing. Paired tumor samples and TILs from melanoma patients were used to assess which compounds when used to treat the melanoma cell lines can enhance the cytotoxic activity of the TILs against the paired melanoma sample, using a flow cytometry based assay in which active caspase 3 was used as a read out of apoptosis. We identified heat shock protein 90 (HSP90) inhibitors amongst compounds that improved T cell mediated cytotoxicity. We show that treatment with the HSP90 inhibitor ganetespib (Synta) greatly improves T cell mediated cytotoxicity of both human and murine cancer cells lines in vitro. Furthermore, in vivo murine studies using the MC38/gp100 tumor model show that ganestespib in combination with anti-CTLA4, resulted in superior antitumor effect and survival compared to either treatment alone (Average tumor volume at day 21 of treatment: Vehicle 294.3mm3, α-CTLA4 193 mm3, Ganetespib 237.5 mm3 and Ganetespib + α-CTLA4 105.8 mm3, P < 0.0001). Microarray analysis of human cell lines treated with ganetespib in vitro revealed an increase in interferon alpha (IFN-α) response genes including IFIT1, IFIT2, IFIT3 and IFIH1. Silencing IFIT2 abrogated the synergy observed with ganetespib treatment and T cell mediated killing, suggesting that the IFN-α response pathway plays an important role in this combination therapy. We are further elucidating the role of these genes in the synergy observed. This will enable the emergence of a new combination therapy of HSP90 inhibitors and anti-CTLA4 for the treatment of melanoma patients that will increase the percentage of patients responding to immunotherapy and achieving long term responses. Citation Format: Rina M. Mbofung, Jodi A. McKenzie, Shruti Malu, Chengwen Liu, Leila Williams, Weiyi Peng, Zhe Wang, Satyendra Tripathi, Trang Tieu, Shuping Zhao, Seram Devi, Isere Kuiatse, Emily Ashkin, Leah Bailey, Jason Roszik, Samir Hanash, Timothy Heffernan, Richard E. Davis, Rodabe N. Amaria, Patrick Hwu. Inhibition of HSP90 enhances T cell-mediated antitumor immune responses through expression of interferon-alpha response Genes. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4360.

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Rina M. Mbofung

University of Texas MD Anderson Cancer Center

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Patrick Hwu

University of Texas MD Anderson Cancer Center

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Jodi A. McKenzie

University of Texas MD Anderson Cancer Center

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Weiyi Peng

University of Texas MD Anderson Cancer Center

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Shruti Malu

University of Texas MD Anderson Cancer Center

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Rodabe N. Amaria

University of Texas MD Anderson Cancer Center

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Trang Tieu

University of Texas MD Anderson Cancer Center

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Chantale Bernatchez

University of Texas MD Anderson Cancer Center

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Jason Roszik

University of Texas MD Anderson Cancer Center

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Chengwen Liu

University of Texas MD Anderson Cancer Center

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