Circulating tumor DNA

With the development of increasingly potent and selective ALK tyrosine kinase inhibitors (TKIs), resistance is commonly mediated by ALK-independent mechanisms, such as bypass pathway activation. As bypass signaling dependencies vary across ALK-rearranged (ALK+) lung cancers, a multipronged approach is needed to broadly suppress potential bypass signals. We have identified MET activation in 20% of ALK+ tumors that are resistant to next-generation ALK TKIs. In preclinical studies, dual ALK/MET blockade re-sensitized MET-amplified ALK+ tumors to lorlatinib. MEK and SHP2 have recently been identified as important effector proteins downstream of several bypass signaling pathways. In ALK+ models harboring diverse bypass signals, pairing an ALK TKI with either a MEK or SHP2 inhibitor demonstrated broad anti-proliferative activity. Based on these findings, we will conduct a clinical trial to evaluate lorlatinib in combination with a MET, MEK, or SHP2 inhibitor for patients with ALK+ lung cancers with ALK-independent resistance. Serial tumor biopsies will be analyzed to characterize molecular determinants of response to combination therapy and identify expression changes induced by treatment. This innovative multi-arm trial will also assess whether dynamics of genetic alterations in plasma can be used to guide intensification of treatment from monotherapy to early combination therapy for patients who have not yet developed resistance to ALK-directed therapy. Collectively, the studies in this grant strive to develop diverse strategies for overcoming ALK-independent resistance, a heterogeneous molecular entity that undermines efficacy of current ALK therapeutics.

Metastatic non-small cell lung cancer (mNSCLC) is the leading cause of cancer-related death in the United States. Most patients with mNSCLC are treated with systemic agents, which prolong survival and improve symptoms, but are typically not curative. Although recent advancements in immune checkpoint inhibitors have revolutionized the management of mNSCLC lacking targetable driver mutations, only a fraction of mNSCLC patients benefit from immunotherapy. Emerging evidence suggests that ablative radiotherapy can augment immunotherapy responses in metastatic disease; however, strategies to optimize the synergy between local radiation and the immune system are not well defined. We are conducting a randomized phase I/II clinical trial designed to evaluate the safety and efficacy of combination immune checkpoint blockade (ipilimumab + nivolumab) plus multisite ablative radiotherapy as a first-line treatment for patients with mNSCLC. As a secondary analysis of the phase I trial, we propose to investigate biomarkers associated with treatment response. In Aim 1, we propose to compare the diagnostic accuracy of established clinical biomarkers, including PD-L1 immunohistochemistry (IHC), tumor mutational burden, gene expression profiles, and multiplex IHC in predicting response to combination ablative radiotherapy and immunotherapy. In Aim 2, we propose to characterize global transcriptional and genomic changes induced by radiation when given prior to or concurrently with immunotherapy and evaluate whether these changes are associated with treatment response. In addition, in Aim 3, we propose to validate a novel biomarker derived from alternative splicing as a predictor of radio-immunotherapy response. By elucidating the immunomodulatory properties of radiotherapy, we may be able to improve treatment responses and long-term survival in patients with mNSCLC.

Small cell lung cancer (SCLC) is an aggressive, neuroendocrine malignancy that accounts for approximately 15% of lung cancers. Despite recent advances, including the approval of immunotherapy combined with chemotherapy for frontline treatment, the median overall survival for patients with extensive-stage SCLC remains approximately one year. These dismal outcomes are attributable, in part, to the lack of approved biomarkers for SCLC, which, in turn, is due to the dearth of available tissue for molecular analysis. Using transcriptomic data, we have developed a gene signature that defines four distinct molecular subtypes of SCLC – each with unique biology and therapeutic vulnerabilities. These subtypes are driven by the presence (or absence) of three transcription factors (ASCL1 – SCLC-A; NEUROD1 – SCLC-N; POU2F3 – SCLC-P; and a fourth triple-negative subtype “Inflamed” – SCLC-I) that are largely mutually exclusive. Our preliminary data suggests that inter- and intra-tumoral heterogeneity among these subtypes drives response and resistance to standard and novel therapies for SCLC, including classes such as PARP inhibitors (PARPi) and immunotherapy. We propose applying bulk and single-cell molecular approaches to assign and longitudinally monitor subtype among our established cohort of patient-derived xenograft models treated with PARPi, as well as patient tumor biopsies from an investigator-initiated trial assessing a PARPi/immunotherapy combination. Based on our preliminary data, we hypothesize that SCLC-P and SCLC-I will preferentially benefit from PARP inhibitors and immunotherapy, respectively, and that subtype shifts detectable at the single-cell level along with accompanying shifts in the composition of the immune microenvironment, will govern response and resistance.

The majority of lung cancer patients present with advanced disease that is largely incurable. Efforts to improve the early detection of this disease are critical to decrease lung cancer-related mortality. Low-dose computed tomography (CT) screening in high risk patients has demonstrated reduction in lung cancer related mortality through diagnosis of earlier stage disease at the cost of high false-positive rates and the frequent need for invasive diagnostic testing when indeterminate lung nodules are identified. Detecting tumor specific somatic mutations and/or epigenetic signatures in circulating tumor DNA (ctDNA) represents an attractive non-invasive method for identifying early stage lung cancer. However, to realize this promise for lung cancer screening, where ctDNA from small tumors is miniscule, the development of sensitive, specific, and economical ctDNA based assays is critical. 
The bacterial innate immune system consisting of clustered regularly interspaced short palindromic repeats (CRISPR) and their associated endonucleases (CRISPR-Cas) are specifically adapted to recognize foreign nucleic acids. The recent identification and diagnostic adaptation of certain classes of CRISPR-Cas systems, such as CRISPR-Cas12a and -Cas13a, offer unique platforms on which to develop sensitive, specific, and economical assays for the detection of ctDNA. The goal of the current project is to develop CRISPR-Cas12a and -Cas13a based ctDNA assays that can sensitively detect somatic cancer mutations and aberrant promoter hypermethylation often found in lung cancer patients and to validate these assays in plasma samples of patients with early stage NSCLC and in discriminating between benign and malignant nodules identified by low-dose CT screening studies. 

Immune checkpoint blockade (ICB) has demonstrated profound effects on the anti-tumor immune response and has revolutionized the treatment landscape of non-small cell lung cancer (NSCLC). While chemotherapy has traditionally been viewed as detrimental to the immune system, recent clinical trials have demonstrated an impressive survival benefit when combining checkpoint blockade with chemotherapy (ICB+chemo) relative to chemotherapy alone. Despite this, many NSCLC patients do not achieve clinical benefit from ICB, even when combined with chemotherapy. The role of tumor mutational burden, and specifically T cells targeting neoantigens derived from these mutations, has been demonstrated in several ICB studies, however these factors have yet to be fully explored in chemotherapy-containing ICB treatment regimens. There is thus an urgent need to understand the effects of ICB+chemo on the anti-tumor immune response and to specifically evaluate how chemotherapy perturbs the phenotype and function of anti-tumor T cells. It is of paramount importance that we understand how PD-1 blockade and chemotherapy synergize to promote anti-tumor immunity in order to better stratify patients most likely to benefit from these treatments. We propose herein to perform the first comprehensive evaluation of the phenotype and function of neoantigen-specific T cells and their dynamics before and after treatment with ICB+chemo relative to ICB alone. The findings from this study will provide a detailed atlas of the immune system dynamics following treatment and will result in the development of an immunometabolic signature that will be correlated with clinical outcome. Importantly, the results of the proposed work will deepen our understanding of the immune response to ICB+chemo and will unravel the mechanisms underlying clinical response in NSCLC patients.

Statement of the Problem: Currently, low dose CT (LDCT) screening for lung cancer is recommended for high-risk individuals, defined as current or former smokers (quit within the past 15 years) with a 30-or-more pack-year smoking history, 55 to 74 years of age, and with no evidence of lung cancer. However, uptake of LDCT screening has been impeded by high rates of false-positive results, which in turn add significant physical and emotional stress to patients as well as additional healthcare costs. Since LDCT is now commonly available, lung nodules detected in LDCT scans are plentiful, but imprecise guidelines for care make it a challenge to ensure quality follow-up and expedited diagnoses for those with lung cancer. Furthermore, screening is not available for those who don’t meet the screening criteria (younger age or low smoking history) when they are the exact population among whom lung cancer rates are rising.

Proposed Solution: Leveraging expertise of academic research centers (Massachusetts General Hospital, Broad Institute, and Stanford University) and a non-profit managed-care consortium (Kaiser Permanente), the Dream Team will develop a test called the Lung Cancer Interception Assay (LCIA) to complement LDCT screening.

The proposal is novel in that it will develop complex computational algorithms to combine high-sensitivity/high-accuracy blood-based molecular biomarkers with image-based biomarkers to create the  LCIA assay. At the end of the award period, a streamlined product, the LCIA, will be ready to use in population-level definitive trials for the early detection of lung cancer.

Background: Osimertinib and other “third-generation” EGFR TKIs effectively overcome T790M-mediated resistance in EGFR-mutant lung cancer, but our understanding of acquired resistance in this setting remains limited. Importantly, the intrinsic heterogeneity of resistant cancers leads to clinical challenges. We hypothesize that in-depth study of 3rd-generation TKI resistance and the impact of genetic heterogeneity on treatment response will lead to improved therapeutic options and clinical outcomes. Study Design: We will analyze tumor biopsies, ctDNA and autopsy specimens using a variety of techniques such as next-generation sequencing, digital droplet PCR and whole exome sequencing to characterize heterogeneity in resistant cancers. In addition, we will run a prospective clinical trial to test a novel therapeutic combination designed to minimize heterogeneity and delay progression. On-treatment biopsies and ctDNA collection will be used to study how resistance develops. Impact: This project will leverage our broad array of clinical specimens, well-established translational research program and preexisting industry and academic collaborations to characterize the heterogeneity of resistance in EGFR-mutant lung cancer. We hope to illuminate clinical and biologic implications of heterogeneity, with the ultimate goal of identifying more effective therapies for patients.

Immune-targeted agents have generated antitumor responses that are transforming cancer therapeutics in various tumors types including lung cancer. Despite the impressive responses observed, the majority of patients eventually experience therapeutic resistance after an initial response. Considering the increased cost to patients and health systems both financially and in terms of time spent in management of immune-related adverse effects it has become clear that success of immuno-oncology approaches depends on choosing patient populations most likely to benefit. Our proposed research addresses the urgent unmet clinical need to understand the underlying biology of response and develop molecular assays of response and resistance to immune targeted agents. We propose comprehensive genome-wide analyses of tumors and cell-free circulating DNA to examine how cancer genomes change during immune checkpoint blockade. Our approach is focused on discovery of mechanisms of resistance using a multidimensional strategy that combines comprehensive genomic analyses with functional assays of autologous T-cell reactivity. The underlying premise of this proposal is that through our comprehensive molecular analyses, we will identify changes in the genomic landscape of tumors during immune checkpoint blockade that mediate emergence of primary and acquired resistance to these therapies. Unravelling the genomic mechanisms through which cancer adapts to evade anti-tumor immune responses will be critical for future development of tailored cancer immunotherapy strategies. We envision that the results of the proposed research will be used to develop patient-specific immunotherapy approaches in lung cancer and will launch investigator-initiated clinical trials at Hopkins and other institutions.

The release of small amounts of cell-free DNA into the bloodstream from dying tumor cells has been well documented in patients with various malignancies. Driven by improvements in assay technologies, such circulating tumor DNA (ctDNA) is beginning to show excellent promise as a non-invasive cancer biomarker. Because unique somatic mutations can serve as telltale marks to distinguish tumor-derived DNA in plasma, the cancer specificity of ctDNA is expected to be very high, making it an attractive candidate as a biomarker for cancer screening. Because many somatic mutations in non-small cell lung cancer (NSCLC) are found clustered with high frequency within a small set of genes, detection of ctDNA in such patients is technically more tractable. We have created a highly multiplexed, ultrasensitive assay that uses next-generation sequencing techniques to quantify low-abundance mutant DNA fragments in plasma against a large excess of background wild-type DNA. Our assay can simultaneously evaluate mutations in 40 different hotspots in up to 96 patient samples, using novel error suppression methods to optimize detection sensitivity. We have shown that the assay is capable of measuring very small amounts of mutant ctDNA in a limited set of patients with early-stage disease or with small, localized recurrences. We now aim to test the clinical performance of the assay on a larger scale. We propose to perform a case-control study comparing patients with early-stage NSCLC to individuals with a heavy smoking history or individuals having benign pulmonary nodules.