Multiple immunotherapies have demonstrated long-term clinical benefit in patients with melanoma. Clinical trials are currently underway to build upon this activity in melanoma, and to see if similar benefits can be achieved in other cancers. Despite the advances made over the last few years, there is currently limited understanding of the mechanisms of resistance to immunotherapy. An improved understanding of resistance may identify patients that are most likely to benefit from current immunotherapies. Further, identification of resistance mechanisms that are targetable may lead to combinations that are more effective. Previously we demonstrated that targeting BRAFV600 mutations, which are the most common somatic alterations in melanoma, increases the efficacy of immune-mediated killing of tumors through multiple mechanisms, leading to ongoing clinical trials. Recently, we have found evidence that loss of the tumor suppressor PTEN, which occurs in 20-30% of melanomas with BRAFV600 mutations, may also contribute to resistance to immunotherapy. Our preliminary experiments show that loss of PTEN in BRAF-mutant melanoma cells inhibits T-cell mediated killing of melanomas in vitro , decreases intratumoral accumulation of tumor-infiltrating T cells (TIL) in vivo, and correlates with reduced success of TIL expansion from patients. Our data also demonstrates that loss of PTEN correlates with inferior clinical outcomes among BRAF-mutant melanoma patients, reinforcing the clinical significance of this subpopulation. Loss of PTEN results in marked activation of the PI3K-AKT pathway, a pathway for which many targeted agents are available and currently undergoing clinical testing. Thus, our central hypothesis is that the PI3K-AKT pathway in tumor cells is the critical mechanism of resistance to immunotherapy in BRAF-mutant melanomas, and that inhibition of this pathway will increase the efficacy of T-cell mediated immunotherapy. In order to test this hypothesis, we will utilize multiple unique clinical and preclinical resources that we have established to develop more effective therapeutic approaches for melanoma patients. First, we will utilize our preclinical models and diagnostic platforms to interrogate the mechanisms that underlie resistance to T-cell mediated killing and trafficking of T cells to melanoma with loss of PTEN. Second, we will analyze specimens from several cohorts of melanoma patients to determine the immunological features and immunotherapy treatment outcomes associated with PTEN loss. Finally, we will determine the effects of PI3K-AKT pathway inhibitors, alone and in combination with FDA-approved BRAF inhibitors, on T-cell viability, function, and anti-tumor activity in vitro and in vio. Together these studies will improve our understanding of the role and therapeutic potential of the PI3K-AKT pathway in resistance to immunotherapy in melanoma. Further, as the PI3K-AKT pathway is implicated in multiple tumor types in which immunotherapies are being tested, the findings may have broad applications for cancer patients.

Public Health Relevance

Immunotherapies have demonstrated durable cures in many patients with metastatic melanoma, the most aggressive form of skin cancer. In this proposal, the investigators will determine the role of the PI3K-AKT pathway in resistance to immunotherapy for advanced melanoma. The potential benefits of these studies include identifying patients who are most likely to benefit from immunotherapies, and the development of personalized combinations that may overcome resistance mechanisms for future testing in clinical trials.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA187076-03
Application #
9099792
Study Section
Cancer Immunopathology and Immunotherapy Study Section (CII)
Program Officer
Muszynski, Karen
Project Start
2014-08-13
Project End
2019-07-31
Budget Start
2016-08-01
Budget End
2017-07-31
Support Year
3
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of Texas MD Anderson Cancer Center
Department
Internal Medicine/Medicine
Type
Hospitals
DUNS #
800772139
City
Houston
State
TX
Country
United States
Zip Code
77030
Cascone, Tina; McKenzie, Jodi A; Mbofung, Rina M et al. (2018) Increased Tumor Glycolysis Characterizes Immune Resistance to Adoptive T Cell Therapy. Cell Metab 27:977-987.e4
Yam, Clinton; Xu, Xiaowei; Davies, Michael A et al. (2018) A Multicenter Phase I Study Evaluating Dual PI3K and BRAF Inhibition with PX-866 and Vemurafenib in Patients with Advanced BRAF V600-Mutant Solid Tumors. Clin Cancer Res 24:22-32
Mbofung, Rina M; McKenzie, Jodi A; Malu, Shruti et al. (2017) HSP90 inhibition enhances cancer immunotherapy by upregulating interferon response genes. Nat Commun 8:451
Roh, Whijae; Chen, Pei-Ling; Reuben, Alexandre et al. (2017) Integrated molecular analysis of tumor biopsies on sequential CTLA-4 and PD-1 blockade reveals markers of response and resistance. Sci Transl Med 9:
Glitza Oliva, Isabella; Tawbi, Hussein; Davies, Michael A (2017) Melanoma Brain Metastases: Current Areas of Investigation and Future Directions. Cancer J 23:68-74
Kim, Dae Won; Haydu, Lauren E; Joon, Aron Y et al. (2017) Clinicopathological features and clinical outcomes associated with TP53 and BRAFNon-V600 mutations in cutaneous melanoma patients. Cancer 123:1372-1381
Huang, L; Wang, Z; Liu, C et al. (2017) CpG-based immunotherapy impairs antitumor activity of BRAF inhibitors in a B-cell-dependent manner. Oncogene 36:4081-4086
Peng, Weiyi; McKenzie, Jodi A; Hwu, Patrick (2016) Complementing T-cell Function: An Inhibitory Role of the Complement System in T-cell-Mediated Antitumor Immunity. Cancer Discov 6:953-5
Chen, Guo; McQuade, Jennifer L; Panka, David J et al. (2016) Clinical, Molecular, and Immune Analysis of Dabrafenib-Trametinib Combination Treatment for BRAF Inhibitor-Refractory Metastatic Melanoma: A Phase 2 Clinical Trial. JAMA Oncol 2:1056-64
Peng, Weiyi; Chen, Jie Qing; Liu, Chengwen et al. (2016) Loss of PTEN Promotes Resistance to T Cell-Mediated Immunotherapy. Cancer Discov 6:202-16

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