Immunotherapy

An estimated 160,000 patients die each year from non-small cell lung cancer (NSCLC), primarily due to the development of metastatic and treatment-refractory disease. Dr. Byers, Dr. Gibbons, and their group have previously demonstrated that the epithelial-mesenchymal transition (EMT) is a unifying mechanism that drives tumor progression, metastasis, resistance to standard therapies, and immune suppression. Furthermore, their group and others have shown that the receptor tyrosine kinase Axl and PD-L1 are overexpressed on tumor cells in the setting of EMT in NSCLC and that targeting either Axl or PD-L1 results in preclinical efficacy in lung cancer models.

Based on these results, they have initiated the first clinical trials of BGB324 (a first-in-class, selective Axl inhibitor) for lung cancer patients in combination with either erlotinib or chemotherapy. They hypothesize that Axl is a driver of EMT and EMT-associated immune escape. Therefore, in this project they will use pre-clinical cell line and animal models to determine the role of Axl in driving EMT, identify predictive markers of response to Axl inhibition, and investigate the efficacy of combination therapy with an Axl inhibitor and an immune checkpoint inhibitor, anti-PD-L1. The biomarkers identified in their preclinical models will be directly tested in fresh tumor biopsies from their Phase 1/2 clinical trial that combines erlotinib with BGB324.

Although NSCLC is a molecularly heterogeneous disease, EMT is a potential universal mechanism of progression and drug resistance across many molecular subtypes. It is their goal to leverage this finding to develop single agent or combination treatment strategies that can be used across the molecular spectrum.

Melanoma has the highest propensity to metastasize to the brain once the disease has spread, while non-small cell lung cancer (NSCLC) has the highest incidence of brain metastases among all cancers. Approximately 50,000 patients develop brain metastases from these diseases every year. Patients with brain metastases have exceedingly limited therapeutic options since they are typically excluded from clinical trials. Recently a number of new systemic immune therapies, such as nivolumab (BMS-936558) and lambrolizumab (MK-3475), two inhibitors of PD-1 (an immune inhibitory molecule), have led to dramatic responses in metastatic melanoma (MM) and NSCLC. However, these therapies have not been studied in patients with untreated brain metastases.  Little is known about immune cells in the brain, and whether the immune system can be stimulated to reject cancer cells. Moreover, little is known about what tumor characteristics are associated with response to MK-3475 in brain metastases. This proposal includes innovative correlative biomarker studies incorporated into a clinical trial uniquely designed to study the activity of MK-3475 in patients with limited, small brain metastases in MM and NSCLC. This drug carries the hope to provide prolonged responses similar to responses seen in other metastatic sites, and might enable patients to avoid radiation therapy, and improve their outcome. As part of this clinical trial, we will collect brain and other metastatic specimens from patients enrolled and study the expression of immune inhibitory molecules utilizing a novel quantitative assay and algorithms that we have developed in preliminary work. These studies will facilitate selection of patients who are more likely to respond to this class of drugs.

Small cell lung carcinoma (SCLC) remains one of the most lethal human cancers. More than 25,000 patients are diagnosed with SCLC every year in the United States. Unfortunately, most patients usually survive only 6-12 months after diagnosis. Except for the combination of radiation therapy and chemotherapy, there has been no novel therapeutic approach implemented in the past 30 years. Despite a large number of clinical trials, no targeted therapy has been approved for SCLC patients, whose survival rate hovers around 5%. Previous attempts to identify therapeutic targets in SCLC patients have mostly focused on signaling networks within the tumor cells. Here we propose to test a novel immunotherapeutic approach to promote the anti-cancer activity of macrophages. Specifically, we found that SCLC cells express high levels of the CD47 antigen, a marker of self that inhibits the phagocytic activity of macrophages. Based on previous studies from the laboratories of Dr. Weissman and Dr. Garcia at Stanford, we propose to block the interaction between CD47 and SIRPa, an inhibitory receptor expressed on macrophages, to stimulate the engulfment of SCLC cells by macrophages and their eradication. Furthermore, we will identify SCLC-specific antigens and combine CD47-blocking therapies with these antibodies to enhance the recruitment and the activity of macrophages against SCLC cells. Clinical trials testing the CD47-blocking strategies are being initiated in patients with blood cancer and some solid tumors. If successful, our pre-clinical experiments may lead to the rapid implementation of this novel anti-cancer immunotherapy strategy in SCLC patients.

Advanced (stage IV) lung adenocarcinoma is an incurable disease. Treatment mostly consists of chemotherapy, which provides a consistent but small survival benefit. Standard therapy includes a platinum-doublet (pemetrexed or paclitaxel) often in combination with bevacizumab, followed by maintenance bevacizumab or pemetrexed. Programmed death 1 (PD-1) is a T-cell surface receptor that when activated, delivers a negative signal to T cells. This feedback mechanism dampens immune responses when no longer needed, preventing damaging autoimmune reactions. Tumors can co-opt this T-cell control mechanism to escape surveillance and/or rejection by the immune system. Thus, reversing this tumor action can result in antitumor activity worthy of clinical evaluation. Recently it has been demonstrated that inhibition of the PD-1 receptor with an anti-PD-1 monoclonal antibody (nivolumab) has significant clinical activity in lung cancer with an ORR of 26%. As remarkable as this may be, given the heavily pretreated population of lung cancer patients studied, this also indicates that 74% of patients did not respond and remained resistant to this approach. Therefore, going forward it is important to develop combination therapies to improve the efficacy of this approach, and to discover resistance mechanisms that may allow for better patient (and tumor) selection. One potential class of agents to be used in combination with anti-PD-1 is the adenosine A2AR antagonists. Given that A2AR on T cells within the tumor microenvironment contributes to immune escape and therapeutic resistance, the addition of PBF-509 is expected to improve the efficacy of nivolumab.

Background & Significance: Phase I studies with the anti-programmed death-1 antibody (anti-PD-1), nivolumab, in advanced non-small-cell lung cancer (NSCLC) have demonstrated remarkably durable responses in heavily pretreated patients that lasted a median 17 months. However, in these studies very few patients have had tumors available for immune analysis, and basic data on immune measures pre- and post-treatment are not available. This study will move the treatment paradigm forward by assessing the safety and feasibility of preoperative anti-PD-1 in NSCLC and providing detailed information on the effect of PD-1 modulation on the lung tumor immune microenvironment.

Methods: Patients with newly diagnosed stage IB-IIIA NSCLC will receive two doses of nivolumab 3mg/kg IV on day-28 and day-14 prior to planned surgery on day 0. Serial blood samples for immune markers will be obtained. The primary endpoint of this study is the safety and feasibility of preoperative nivolumab in resectable NSCLC. For the exploratory immune analyses, initial tumor biopsy, post-treatment resection specimen, and serial peripheral blood samples will be evaluated for expression of immune markers with the primary comparison being intra-patient, pre- and post-treatment.

Experimental Approach & Statistical Analysis Plan: As this is the first time that nivolumab has been administered pre-operatively in NSCLC, the study will commence with a run-in phase where six patients will be monitored continuously for adverse events through eight weeks following surgery. Overall, the study will continue without pause to a 12-patient expansion phase if none or one of the six patients experiences DLT in the run-in. Detailed statistical plans for the safety and feasibility endpoints and exploratory immune endpoints are described in the main body of this application.