Immunotherapy

Our laboratory has demonstrated the potency of the abscopal effect in studies showing that high-dose radiation therapy delivered to primary tumors in combination with dual immune checkpoint blockade can significantly inhibit the growth of satellite tumors. The implication of such results is that radiation therapy has remote effects which are immune-mediated and that new radiation protocols can be devised to exploit our naturally occurring defenses against cancer. Previous studies have shown that immune-mediated tumoricidal effects can be augmented by combining high-dose radiation therapy delivered to a primary tumor site with low-dose radiotherapy (LDRT) targeting secondary tumors. Tumor response is further enhanced if systemic agents are employed to induce immune-checkpoint blockade (ICB). Such protocols employing conventional LDRT are known to reduce the number of regulatory T cells (Tregs) and to activate natural killer cells, thereby modulating the tumor microenvironment (TME). Our laboratory project seeks to test a modification of LDRT called pulsed low-dose-rate radiotherapy (PLDR). By providing radiation in repeated very low doses, the PLDR regimen may reduce the encasement of tumors with stromal elements, thus removing a barrier to infiltrating immune-reactive cells. We propose to use the immunocompetent lung cancer murine model which we developed for our earlier research combining HDRT with anti-PD1 and anti-CTLA-4 antibodies. HDRT will again be delivered to primary tumors in combination with dual ICB. Additionally, LDRT will be delivered to secondary tumors, both in conventional form and as PLDR. The results will thus test an innovative method for exploiting the emerging synergies of radiation and ICB. A demonstration of the superior therapeutic utility of PLDR in our animal model would be of immediate relevance to clinical trials seeking improved strategies for treating patients with metastatic lung cancer.

Though the introduction of immune checkpoint inhibitors (ICI) has improved outcomes for patients with stage III non-small-cell lung cancer, most patients do not have robust tumor responses to ICI and real-world patients discontinue ICI due to toxicity at a higher rate than clinical trial populations. There is an unmet need to develop predictive models to identify patients at risk of poor ICI response, high risk of ICI toxicity, and high risk of non-cancer mortality, as these patients are unlikely to benefit from ICI and may require treatment intensification or de-intensification, selection of alternative therapies, or enrollment on clinical trials. In this proposal we seek to leverage the richness and national scale of Veterans Affairs (VA) clinical data to develop statistical models to predict ICI efficacy, toxicity, and non-cancer mortality. We will evaluate specific hypotheses generated from preclinical research and use machine-learning approaches to identify new predictors from high-dimensional VA healthcare data. These models will be integrated into a unified multistate model, allowing prediction of the individualized overall survival benefit of ICI for each patient. Clinical decision-making based on model predictions will be compared to other decision making strategies using decision-curve analysis. This work will identify novel biomarkers of ICI efficacy and toxicity, validate putative ICI effect modifiers from the preclinical literature, and develop the first unified model for ICI clinical benefit. If successful, this tool can be used for patient counseling, physician decision-making, and identification of patients likely to benefit from alternative therapies, treatment de-escalation, or clinical trial enrollment.

The targeted-therapy (TT) osimertinib is frontline standard-of-care for patients with advanced non-small cell lung cancer (NSCLC) harboring mutations in the epidermal growth factor receptor (EGFR) gene. However, nearly all patients develop resistance, at which point treatments are limited. While revolutionary for many cancers, anti-PD-(L)1 immune checkpoint blockade (ICB) has been ineffective in EGFR-mutated(m) NSCLC. Targeting angiogenesis, and specifically vascular endothelial growth factor (VEGF), may be key to changing this. VEGF promotes immunosuppression through multiple mechanisms including inhibition of cytotoxic T-cell trafficking and promotion of regulatory T-cell proliferation. Pre-clinical and clinical evidence has revealed activated EGFR to be a dominant regulator of angiogenesis in EGFRm NSCLC, with increased expression of VEGF and hypoxia inducible factor-1α observed in EGFRm compared to wild-type NSCLC. Clinically, combination chemotherapy with anti-PD-L1 and VEGF blockade has shown efficacy signals in EGFRm NSCLC. However, whether upregulated VEGF potentiates the uninflamed tumor immune microenvironment (TIME), and underlies the observed synergy of these therapies in EGFRm NSCLC, remains unexplored. It is further unknown if VEGF inhibition can be combined with PD-1 blockade to promote benefit in the absence of chemotherapy, or whether blockade of additional checkpoints can further expand anti-tumor immune populations, specifically NK cells, which appear to be upregulated in EGFRm NSCLC responsive to ICB. To address these impactful questions, we have designed a single-arm translationally-focused phase 2 clinical trial assessing the efficacy of tiragolumab (anti-TIGIT) plus atezolizumab (anti-PD-L1) and bevacizumab (anti-VEGF) in advanced TT-refractory, ICB-naïve, EGFRm NSCLC. Critically, the proposed analyses detailed herein of tumor and blood samples obtained pre- and on-treatment will focus on (1) immunopathologic features of ICB resistance in EGFRm-NSCLC and (2) TIME infiltration and immunologic reprogramming imparted by these therapies. The findings from this study will help to define the innate barriers preventing induction of durable anti-tumor immunity by ICB in EGFRm NSCLC, and identify strategies to overcome them.

Although about a third of patients with non-small cell lung cancer (NSCLC) present with resectable disease, a majority will experience death and relapse from their cancer. Exciting recent advances in the use of immune checkpoint inhibition in this early stage space presents a promising way forward for our patients. As the most commonly mutated oncogene, activating KRAS mutations are found in 30% of lung adenocarcinomas; G12C mutations have been associated with higher risk of recurrence following resection. Adagrasib (MRTX849), a potent, highly selective novel small molecule inhibitor of KRAS G12C, has shown promise in previously treated advanced NSCLC. Our study represents a novel application of precision oncology in the resectable NSCLC disease setting with the neoadjuvant use of adagrasib monotherapy or in combination with immune checkpoint inhibition. We will identify safety and clinical efficacy signals of both of these therapeutic approaches. Leveraging our institutional expertise of using single- cell transcriptomics of tumor- infiltrating lymphocytes (TIL), we will evaluate neoantigen-specific transcriptional programs with a focus on KRAS-specific changes, and correlate with clinical outcomes. Overall, our study aims to ultimately improve cure rates of resectable KRAS G12C-mutated NSCLC.

Fusions in the RET proto-oncogene account for ~2% of non-small cell lung cancers (NSCLC). Despite initial failures tied to the use of multi-kinase inhibitors, recent selective RET inhibitors have proven remarkably more successful. However, patients eventually recur on these therapies, highlighting the need for other therapeutic alternatives. Immunotherapies have been unsuccessful in patients harboring RET fusions, likely in part due to their low tumor mutational burden. Neoantigens are immunogenic antigens which are derived from somatic mutations, resulting in antigen-specific killing by T lymphocytes. Importantly, insertions, deletions, and gene fusions may exhibit increased immunogenicity, due to their accrued dissimilarity with unmutated transcripts and proteins, which may provide a unique opportunity to target RET fusions using T cell receptor engineering approaches. Accordingly, we hypothesize that RET fusions are immunogenic and can be effectively recognized using T cell receptor engineering approaches. To confirm this hypothesis, we propose to identify RET fusion-derived neoantigens, identify and isolate the T cells which recognize them, and engineer T cells to kill targets in vitro. Through this work, we aim to generate a library of TCRs which could be used off-the-shelf to target the two dominant RET fusions (KIF5B-RET=75%; CCDC6-RET=25%) and 10 most prevalent HLA alleles in the United States, in order to afford new therapeutic alternatives to the overwhelming majority of patients harboring RET fusions in NSCLC.

Immune checkpoint inhibitors have revolutionized the care of patients with metastatic non-small cell lung cancer (NSCLC). Unfortunately, not all patients benefit from this therapy, and rational combinatorial strategies to enhance immune checkpoint inhibitors (ICI) efficacy in therapy non-responders are needed. We and others have shown that patients with liver metastases derive limited clinical benefit from ICI across a wide variety of disease types. In preclinical models, we discovered that liver metastases cause anti-PD-L1 resistance by siphoning tumor-specific T cells from systemic circulation. Within the liver, activated antigen-specific CD8+ T cells undergo apoptosis. Consequently, liver metastases create a systemic immune desert in preclinical models. Similarly, patients with liver metastases have reduced peripheral T cell numbers and diminished tumoral T cell diversity and function. In preclinical models, liver-directed radiotherapy eliminates immunosuppressive hepatic macrophages, increases hepatic T cell survival, and reduces hepatic siphoning of T cells. The central hypothesis of this proposal is that liver SBRT can enhance CPP therapy non-responders in NSCLC patients with liver metastases. In Aim 1, we will conduct a Phase IB clinical trial establishing the feasibility of delivering multi-target liver SBRT following the first cycle of carboplatin, pembrolizumab, and pemetrexed (CPP) in metastatic NSCLC patients with liver metastases. Up to four liver metastases will be targeted. In Aim 2, we will determine whether liver SBRT combined with ipilimumab and nivolumab modulates the hepatic and systemic immune microenvironment in NSCLC patients with liver metastases. The completion of these aims will assess the feasibility of ablating liver metastases with SBRT in combination with chemoimmunotherapy and deepen our understanding of the contribution of hepatic immune tolerance mechanisms in patients. The ultimate goal of this work is to test rationally-developed combinatorial treatment approaches in hopes of improving the care of NSCLC patients.

Patients with non-small cell lung cancers bearing ALK or ROS1 fusions (FD-NSCLC) often experience an initial, marked response to tyrosine kinase inhibitors (TKI). The eventual emergence of TKI resistance in FD-NSCLC can be partially attributed to cancer-cell intrinsic mechanisms, but these do not fully explain the diversity in patient outcomes. Currently, FD-NSCLC is viewed as a “cold” tumor with only a molecular target, and the role of the tumor microenvironment (TME) in these cancers has not been well studied. As patients have limited options after progression on TKIs, there is an urgent need to identify novel drivers of resistance to develop new, more effective therapies. Based on our preliminary data, we believe innate immune cells, monocytes and macrophages (MoMf), within the FD-NSCLC TME shape tumor response to TKI therapy. Using patient derived cell lines, we found marked TKI resistance in multiple FD-NSCLC cell lines when cultured in media conditioned by MoMf. MoMf-driven TKI resistance was associated sustained pERK activity in the cancer cell. In pre-treatment specimens from patients with FD-NSCLC, multispectral tissue imaging demonstrated a range in number of MoMf within the TME. Our preliminary data suggest the presence of MoMf with the FD-NSCLC TME may alter response to therapy. We propose investigating the mechanisms of MoMf-mediated TKI resistance and potential therapeutic approaches with clinically relevant syngeneic and xenograft animal models and patient-derived FD-NSCLC cell lines. Further, we will examine biopsy specimens from patients
Immunotherapy is a treatment approach that leverages the body’s own immune system to destroy cancer cells. In non-small cell lung cancer (NSCLC), the most common type of lung cancer, immunotherapy has opened the door to durable treatment that approaches cure; unfortunately, this outcome is rare, and many NSCLCs are initially or eventually become unresponsive. It was originally thought that unresponsive malignancies had adapted to prevent immune cells from locating and interacting with the tumor. Our research suggests this is not the case: the tumor can remain inflamed and responsive, but the immune response can become exhausted. Therapies that reinvigorate the immune response (including tumor infiltrating lymphocyte [TIL] therapies) may be particularly effective in this context. In fact, our preliminary studies suggest TIL therapy can work in up to a third of treatment-resistant NSCLCs. Capitalizing on these new insights, our proposal seeks to 1) determine pre-treatment features of sensitivity and resistance to TIL therapy in NSCLC and 2) characterize on-treatment patterns of immune response, focusing on the cells that identify and kill NSCLC cells. Accomplishing these aims will fill critical knowledge gaps, identifying characteristics of tumors likely to respond, or that fail to respond, to TIL treatment. These studies will define a roadmap, guiding application of subsequent TIL research for lung cancer. Taken together, these studies will provide crucial insights into novel treatment approaches for patients with few alternatives and an otherwise grim prognosis.

Lung cancer is the leading cause of cancer-related death in the United States and worldwide. Immune checkpoint inhibitors (ICIs) have shown durable responses and improved survival in some patients with advanced non-small cell lung cancer (NSCLC). However, nearly all patients eventually progress on these therapies, and the median survival for patients with metastatic NSCLC remains around one year. Combining immunotherapy with cytotoxic chemotherapy has shown an incremental benefit but at the cost of increased toxicity. Patients who progress on currently available immunotherapies have few effective treatment options. One significant barrier to ICI therapy efficacy is the tumor microenvironment (TME), which contains immunosuppressive cells including myeloid-derived suppressor cells (MDSCs). MDSCs represent an important tumor immune escape mechanism and play a role in the development and progression of lung cancer. Higher levels of MDSCs in the blood are associated with shorter overall survival in patients with NSCLC, and MDSCs are associated with resistance to immune checkpoint inhibitor (ICI) therapy. However, there is significant variation in methods of measurement of MDSCs including 1) the classification of the most common phenotypes, namely CD15+ polymorphonuclear MDSC (PMN-MDSC) and CD14+ monocytic MDSC (M-MDSC), and 2) the functional assessment of MDSCs. There are also significant differences in MDSC function and phenotype in animal models and in patients with cancer. We propose to investigate the role of MDSCs in tumor immune escape, and to target the immunosuppressive impact of MDSCs to improve outcomes of patients with NSCLC treated with ICI. Utilizing mass cytometry and in vitro co-culture assays, we will evaluate MDSC levels and function as well as immune cell subset changes in patients receiving standard of care immunotherapy to identify the cell populations that drive immune responses and resistance. We will then conduct a phase 1b clinical trial of all-trans retinoic acid (ATRA) combined with atezolizumab to test whether this treatment can improve responses and overcome ICI resistance in patients with NSCLC who have progressed on standard therapies. We hypothesize that a decrease in the frequency and immunosuppressive function of circulating MDSCs will be associated with increased clinical benefit in patients with NSCLC, and that modulation of MDSCs through the use of ATRA given in combination with ICIs will be safe, tolerable, and exhibit preliminary efficacy in overcoming resistance to available ICIs. The proposed studies include the first trial of this novel treatment in patients with lung cancer and will examine the potential for targeting MDSCs to overcome resistance and enhance the efficacy of immunotherapy. If successful, these studies may lead to an increased number of patients with advanced NSCLC experiencing durable responses and improved survival.