Tyrosine kinase inhibitors (TKIs)

EGFR-mutant lung cancers (LC) serve as the prototype oncogene-driven cancer and mechanisms of resistance to EGFR therapy are well-established. Selective pressure of EGFR inhibitors can induce lineage plasticity to escape oncogene-dependence. While we have shown EGFR/TP53/RB1-mutations are necessary but insufficient to induce small cell transformation, no other genomic signatures and transcriptomic/epigenomic effectors that induce transformation have been identified.

Using parallel exome sequencing, bulk RNA sequencing, and bisulfite sequencing, we will characterize the biomarkers of transformation in EGFR/TP53/RB1-mutant LC and mixed adenocarcinoma/squamous cell tumors. We will also utilize single-cell RNA sequencing to identify the transcriptional changes associated with transformation and to identify distinct cell types within a heterogenous tumor. We will reconstruct a phenotypic landscape to identify subclones in a transitional state between histologies. The information obtained from these studies will nominate novel biomarkers of lineage plasticity that will be validated and proposed for study in clinical trials.

The current standard of care for ALK rearranged non-small cell lung cancer (NSCLC) is targeted therapy with ALK tyrosine kinase inhibitors (TKIs) which bind within the kinase domain of ALK. Due to the development of ALK resistance mutations or bypass activation of parallel or downstream signal pathways, patients inevitably relapse. Even with the introduction of second or third generation TKIs, median overall survival has been estimated to be 6.8 years . Recent advances in immunotherapy have demonstrated progress in lung cancer treatment. However, a majority of ALK positive NSCLC patients have yet to realize the benefits from checkpoint inhibitors or CAR-T cell therapies due to primary resistance or toxicity. Therefore, the development of new treatments for ALK-rearranged NSCLC is an area of critical need. We believe that an effective assault on ALK-driven tumors requires the implementation of creative strategies that allow us to expand our arsenal of drugs to target ALK beyond its kinase domain. To meet this challenge, we have developed and employed cysteine druggability mapping (CDM), a method to define the landscape of inhibitor-protein interactions in a cancer cell. CDM identifies cysteines that can bind to covalent drug-like molecules which serve as early prototypes on which to base cancer drug development programs.
Cysteine-reactive covalent inhibitors have already emerged as an effective approach to targeting protein kinases. Osimertinib, a third-generation epidermal growth factor receptor (EGFR) TKI covalent inhibitor, overcomes EGFR T790M resistance mutations following treatment with EGFR TKI, demonstrating significant improvements over standard EGFR TKIs when used as first line therapy. Importantly, targeting cysteines with covalent inhibitors massively expands the number of proteins which are targetable with small molecule inhibitors, including many targets previously considered undruggable.

We will use ALK fusion positive cancer cell lines, together with tumor tissues from patients who developed resistance mechanisms, to generate druggable cysteine profiles by CDM. Druggable proteins specific to ALK fusion positive samples, including EML4-ALK itself, will be prioritized in our screening for protein degraders from a library of over 2,500 advanced cysteine reactive compounds. After screening, we will assess the specificity of the compound hits and validate their anti-tumor activity using ALK fusion positive cell lines and patient derived ALK TKI-resistant cell lines. We consider the use of the novel, cutting-edge cysteine targeting technology to screen for potent therapeutic compounds as a valuable proposition to improve management of patients with ALK positive lung cancer, with the goal of transforming this cancer into a chronic condition.

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.

Several tyrosine kinase inhibitors (TKIs) are available for the treatment of ALK+ NSCLC, but resistance to all ALK TKIs (including alectinib, brigatinib, lorlatinib) has been reported and occurs through a variety of mechanisms. Once patients develop resistance to available ALK inhibitors, they are typically treated with cytotoxic chemotherapy rather than immunotherapy since response rates to PD-1 pathway inhibitors in this population are very low. However, our work in mouse models of ALK+ NSCLC has demonstrated that a vaccine generated against the rearranged portion of ALK can both prevent the development of ALK+ tumors and also more effectively treat them once they arise. We have also recently found evidence for anti-ALK immune responses in patients, as a subset of them generate spontaneous ALK autoantibodies.

We aim to translate our preclinical findings to a first-in-human clinical trial. Aim 1 will test the safety and efficacy of a novel ALK vaccine + an amphiphilic CpG toll-like receptor 9 agonist adjuvant, administered in combination with an ALK TKI or PD-1 inhibitor in patients with TKI-resistant ALK-positive NSCLC. In Aim 2, using liquid chromatography data-independent acquisition mass spectrometry, we will directly identify antigenic ALK peptides presented by MHC molecules on the surface of cancer cells from tumor biopsies obtained on trial participants. In Aim 3, we will study pre- and post-vaccination anti-ALK T-cell responses among trial participants by analyzing peripheral leukocytes and intratumoral immune cells. The overarching goal is to develop a vaccine that stimulates patients’ immune cells to recognize and eliminate ALK+ tumors.

Targeted therapies, such as ALK inhibitors, represent a major advance in the treatment of lung cancer patients with specific oncogenic drivers. However, these patients relapse due to acquired or intrinsic resistance to these agents. While targeting immnoevasive pathways, such as immune checkpoint inhibitors, have shown efficacy in a subset of lung cancer patients who have progressed on other therapies, the response rate in ALK-positive lung cancer to these agents is very low, underscoring the need to identify other potential regulators of the anti-tumor immune response. The complement pathway is a component of the innate immune response, which regulates the adaptive immune system. Complement activation, initiated through multiple pathways, leads to a series of proteolytic cascades that generate inflammatory mediators designated as anaphylatoxins (C3a, C5a).

Our laboratory has employed an immunocompetent orthotopic model of lung cancer progression, where lung cancer cells are implanted into the lungs of syngeneic mice. To study pathways regulating progression of ALK-positive lung cancer, we have developed a panel of murine lung cancer cell lines with the oncogenic driver EML4/ALK. Using both genetic and pharmacological approaches we have demonstrated that while these tumors are resistant to anti-PD-1/anti-PD-L1 therapy, they are strongly inhibited by blocking the complement pathway. This project will define the mechanisms of complement activation, and the cellular and molecular mechanisms whereby complement inhibition blocks ALK-positive tumor progression. Studies will test a panel of complement inhibitors targeting different steps in the complement cascade and validate complement activation in human ALK-positive lung tumors.

ALK rearrangements define a distinct molecular subset of NSCLC and confer sensitivity to treatment with ALK tyrosine kinase inhibitors (TKIs). These agents have produced dramatic improvements in clinical outcomes among ALK-rearranged (ALK+) patients, yet acquired resistance remains a major challenge. Thus, there is an urgent need for alternative therapeutic approaches for this disease. Recently, immune checkpoint inhibitors targeting negative regulators of the immune response (e.g., PD-1/PD-L1) have emerged as powerful new therapies in NSCLC. In preliminary analyses, we and others have observed that ALK+ lung cancers are generally less responsive to immune checkpoint inhibitors. We hypothesize that distinct immune-based strategies may therefore be needed for ALK+ lung cancers. To inform these strategies, we will investigate 1) tumor-intrinsic factors associated with immunogenicity in ALK+ tumors (e.g., neoantigens, tumor mutation burden), 2) tumor-immune cell interactions (e.g., PD-L1 expression, alternative checkpoint expression, antigen presentation), and 3) endogenous T cell responses against ALK in the peripheral blood. Together, these studies may lay the groundwork for development of biomarkers informing optimal delivery of PD-(L)1 therapy in ALK+ lung cancers, while also promoting the development of novel combinations and approaches, including autologous cellular therapies directed against ALK.

Several ALK tyrosine kinase inhibitors (TKIs) are available for the treatment of ALK-rearranged non-small cell lung cancer (NSCLC), but resistance to all ALK TKIs (including crizotinib, ceritinib, alectinib, brigatinib, and lorlatinib) has been reported and occurs through a variety of mechanisms. Once patients develop resistance to available ALK inhibitors, they are typically treated with cytotoxic chemotherapy rather than immunotherapy since response rates to PD-1 pathway inhibitors in this population are very low. However, our work in mouse models of ALK-positive NSCLC has demonstrated that a vaccine generated against the rearranged portion of ALK can both prevent the development of ALK-positive tumors and also more effectively treat them once they arise. In addition, we have recently found evidence of an anti-ALK immune response in patients, as a subset of them generate spontaneous ALK autoantibodies.

To more deeply characterize anti-ALK immunologic responses in patients, we propose (Aim 1) to determine if the presence of anti-ALK antibodies correlates with progression-free and overall survival among patients with ALK-positive NSCLC, and (Aim 2) to directly identify and validate antigenic ALK peptides in different HLA-haplotype backgrounds. Antigenic peptides that are identified through these studies will serve as the basis for a therapeutic ALK peptide vaccine clinical trial, for which funding has been secured independently.

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.