A primary focus of my translational research program is the delineation of epigenetic mechanisms dysregulating gene expression in thoracic malignancies, and the development of novel and effective pharmacologic regimens targeting the epigenome in these neoplasms. To date, more than 100 patients with lung and esophageal cancers and pleural mesotheliomas, as well as patients with pulmonary metastases from non-thoracic malignancies have been treated on a series of clinical protocols examining toxicities and clinical responses following infusions of DNA demethylating agents (Decitabine; DAC), and HDAC inhibitors, such as romidepsin (DP) alone or in combination with other investigational agents such as flavopiridol. Although no objective clinical regressions have been observed, prolonged stabilization of disease has been seen in approximately 10% of patients. Additionally, molecular responses such as induction of p16 and p21 tumor suppressor genes, as well as up-regulation of MAGE-3 and NY-ESO-1 cancer-testis genes with serologic responses to the respective antigens have been observed in 25-50% of patients. Micro-array analysis of laser captured tumor cells revealed that the epigenetic treatment regimens induced a shift from a lung cancer gene signature to one observed in normal respiratory epithelia. Collectively, these early trials provided proof of concept for the use of epigenetic regimens to simultaneously induce apoptosis and augment immunogenicity of thoracic malignancies, and support further efforts to optimize epigenetic regimens for cancer therapy. Our goal has always been to couple epigenetic priming regimens with immunotherapy for thoracic malignancies. Because thoracic cancers exhibit different endogenous as well as drug-induced signatures of cancer-testis antigen expression, we have sought to ascertain if allogeneic tumor cell vaccines can induce broad immunity to cancer-testis antigens in patients with these malignancies. Cancer-testis antigens are preferentially expressed in pluripotent cancer cells; as such, vaccines that induce immunity to these proteins could enhance immune surveillance against cancer stem cells. In an ongoing first-in-humans trial, 21 patients with thoracic malignancies rendered NED by conventional therapy have been randomized to receive a protein lysate vaccine produced from H1299 lung cancer cells exhibiting high-level cancer-testis antigen expression; the vaccine is administered with Iscomatrix adjuvant via intradermal injection q month x 6 +/- oral metronomic cyclophosphamide and celecoxib. The primary endpoint of the trial is serologic response to purified tumor antigens one month after the 6th vaccination. All patients have exhibited local and systemic inflammatory responses lasting 72-96 hours following vaccinations. There have been no treatment related toxicities. 14 patients (67%) completed all six vaccinations; 7 patients were removed from study early due to disease recurrence. 8 patients (57%) exhibited serologic responses to NY-ESO-1. Additional responses were observed against GAGE7, XAGE and MAGE-C2. Additional studies have demonstrated serologic responses to several carbohydrate antigens expressed in human cancer cells, as well as modulation of peripheral immune subsets in a manner that would be expected to enhance antitumor immunity. This trial has been on hold due to pharmacy and production issues, but is expected to resume soon. Some of the results of the trial were presented at the Aspen Lung Conference, and a more comprehensive overview of this trial will be presented at the IASLC World Lung Cancer Conference in September 2018. A manuscript pertaining to these findings is being finalized for publication. A major limitation regarding the use of DNA demethylating agents such as DAC and azacytidine (AZA) in cancer immunotherapy regimens pertains to the short half-life (5min) and poor biodistribution of these drugs due to cytidine deaminase (CDA) which is present at highlevels throughout the body. Recent studies in non-human primates and a clinical trial in patients with sickle cell disease, have demonstrated that an oral formulation of tetrahydrouridine (THU) can markedly increase Cmax (50nM) and T1/2 (4 hours) of oral DAC, and mediate systemic DNA demethylation with no systemic toxicities. These findings have provided the rationale for an ongoing phase II trial evaluation oral DAC/THU and the immune checkpoint inhibitor nivolumab as second line therapy for patients with NSCLC, as well as a phase I/II study of oral DAC/THU and pembrolizumab as first line therapy for patients with inoperable NSCLC. Comprehensive state of the art translational analyses of PD endpoints are being performed for both trials. An overview of the rationale and results of these epigenetic-immunotherapy efforts was presented in a large cancer immunotherapy symposium at ASCO in June, and a manuscript pertaining to this work has been accepted for publication. Lastly, to further optimize epigenetic priming of pulmonary malignancies for immune checkpoint blockade, we have initiated a protocol to examine the toxicities and potential efficacy of aerosolized AZA and oral THU in combination with M7824, a duel immune checkpoint inhibitor-TGF-beta trap in patients with locally advanced lung cancers or pulmonary metastases. This novel protocol as well as the oral DAC/THU and immune checkpoint inhibitor trials are unique to the CCR.
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