Immune checkpoint inhibitors

Anti–PD-1 therapy has transformed the management of NSCLC, but only a subset of patients respond to anti–PD-1 therapy, and responses are rarely curative. Understanding the effects of anti–PD-1 therapy on the composition and functional state of tumor-associated immune subsets can identify mechanisms of response and resistance to anti–PD-1 therapy and provide insights into rational combination strategies to improve upon response rates. Although the effects of anti–PD-1 therapy within the tumor immune microenvironment in preclinical and human subjects have been previously reported, we propose to broadly characterize the effects of anti–PD-1 therapy on the tumor draining lymph nodes (TDLN). Studying the TDLN is particularly valuable because it is the primary sites at which the tumor antigen exposure and the main site of immune T-cell differentiation. To determine the effect of ICI response in the lymph node, we have created an immunocompetent murine model that recapitulates early-stage treatment and outcomes in patients. Additionally, we have characterized TDLN T cells from early-stage cancer patients and have been able to recapitulate our preclinical findings of unique memory T-cell subsets. Our preliminary results of the immune cell type composition, checkpoint expression, and cytokine expression within TDLNs suggest that there are major remodeling events within the TDLN mediated by anti–PD-1 therapy that are critical for conferring effective antitumor long-term immune responses. We demonstrate that unique memory T cell subsets undergo significant activation, expansion, and maturation in response to anti–PD-1 therapy, to shape antitumor programming in TDLNs. Importantly, our proposed study will provide a methodological demonstration in both a murine model and human TDLN that simultaneous uses Flowcytometry, functional immune assays and single cell sequencing that will enable deep interrogation of the immune profile to PD-1 inhibition resistant and responsive patients.

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.

Despite recent advances, locally advanced non-small cell lung cancer (LA-NSCLC) continues to have a high degree of morbidity and mortality related to both disease progression and sequelae from treatment. The purpose of this study is to develop and evaluate a more personalized radiation therapy (RT) approach with the potential to reduce time and financial burden to patients and increase tumor control. Patients undergoing fractionated RT with concurrent systemic therapy for LA-NSCLC will be treated to a total dose of 60 Gy with the number of fractions determined by ability to meet key dose constraints resulting in a shorter treatment course and higher biologic effective dose (BED) among those treated with shorter fractionation. To reduce the iterative time to determine fractionation schedule and standardize the"‘isotoxic hypofractionation" approach, we will employ a previously developed automated RT planning technique after delineation of the tumor and organs at risk. Fifty patients will be enrolled in a prospective non-randomized 2-stage trial to test the primary objective of whether isotoxic hypofractionation results in an acceptable rate of grade 2 or higher toxicity. Secondary endpoints will include G3+ toxicity, local control, progression free survival and overall survival. Finally, to better inform future "isotoxic" dosing strategies we will evaluate additional predictors of radiation toxicity using established retrospective cohorts through the Stanford Cancer Institute and the Veteran’s Affairs Information and Computing Infrastructure (VINCI).

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.