Recent accomplishments include the following: [ ] PHASE I STUDY OF A POXVIRAL TRICOM-BASED VACCINE DIRECTED AGAINST THE TRANSCRIPTION FACTOR BRACHYURY. The transcription factor brachyury has been shown in preclinical studies to be a driver of the epithelial-to-mesenchymal transition (EMT) and resistance to therapy of human tumor cells. This study describes the characterization of a Modified Vaccinia Ankara (MVA) vector-based vaccine expressing the transgenes for brachyury and three human costimulatory molecules (B7.1, ICAM-1, and LFA-3, designated TRICOM) and a phase I study with this vaccine. Human dendritic cells (DC) were infected with MVA-brachyury-TRICOM to define their ability to activate brachyury-specific T cells. A dose-escalation phase I study (NCT02179515) was conducted in advanced cancer patients (n = 38) to define safety and to identify brachyury-specific T-cell responses. MVA-brachyury-TRICOM-infected human DCs activated CD8+ and CD4+ T cells specific against the self-antigen brachyury in vitro. No dose-limiting toxicities were observed due to vaccine in cancer patients at any of the three dose levels. Brachyury-specific T-cell responses were observed at all dose levels and in most patients. The MVA-brachyury-TRICOM vaccine directed against a transcription factor known to mediate EMT can be administered safely in patients with advanced cancer and can activate brachyury-specific T cells in vitro and in patients. Further studies of this vaccine in combination therapies are warranted and planned. [ ] A PHASE 1 DOSE-ESCALATION TRIAL OF BN-CV301, A RECOMBINANT POXVIRAL VACCINE TARGETING MUC-1 AND CEA WITH COSTIMULATORY MOLECULES: BN-CV301 is a poxviral-based vaccine comprised of recombinant (rec.) Modified vaccinia Ankara (MVA-BN-CV301; prime) and rec. fowlpox (FPV-CV301; boost). Like its predecessor PANVAC, BN-CV301 contains transgenes encoding tumor-associated antigens, MUC1 and CEA, as well as costimulatory molecules (B7.1, ICAM-1, LFA-3). PANVAC was re-engineered to make it safer and more antigenic. There were no dose limiting toxicities. Twelve patients enrolled on trial (DL1=3, DL2=3, DL3=6). Most side effects were seen with the prime doses and lessened with subsequent boosters. Antigen-specific T-cells to MUC1 and CEA, as well as to a cascade antigen, brachyury, were generated in most patients. Single agent BN-CV301 produced a confirmed partial response (PR) in one patient and prolonged stable disease (SD) in multiple patients, most notably in KRAS mutant gastrointestinal tumors. Furthermore, two patients with KRAS mutant colorectal cancer had prolonged SD when treated with an anti-PD-L1 antibody following BN-CV301. The BN-CV301 vaccine can be safely administered to patients with advanced cancer. Further studies of the vaccine in combination with other agents are planned. [ ] ANALYSES OF THE PERIPHERAL IMMUNOME FOLLOWING MULTIPLE ADMINISTRATIONS OF AVELUMAB, A HUMAN IgG1 ANTI-PD-L1 MONOCLONAL ANTIBODY. Multiple anti-PD-L1/PD-1 checkpoint monoclonal antibodies (MAbs) have shown clear evidence of clinical benefit. All except one have been designed or engineered to omit the possibility to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) as a second potential mode of anti-tumor activity; the reason for this is the concern of lysis of PD-L1 positive immune cells. Avelumab is a fully human IgG1 MAb, which has been shown in prior in vitro studies to mediate ADCC versus a range of human tumor cells, and clinical studies have demonstrated anti-tumor activity versus a range of human cancers. This study was designed to investigate the effect on immune cell subsets in the peripheral blood of cancer patients prior to and following multiple administrations of avelumab. One hundred twenty-three distinct immune cell subsets in the peripheral blood of cancer patients (n = 28) in a Phase I trial were analyzed by flow cytometry prior to and following one, three, and nine cycles of avelumab. Changes in soluble (s) CD27 and sCD40L in plasma were also evaluated. In vitro studies were also performed to determine if avelumab would mediate ADCC of peripheral blood mononuclear cells (PBMC). No statistically significant changes in any of the 123 immune cell subsets analyzed were observed at any dose level, or number of doses, of avelumab. Increases in the ratio of sCD27:sCD40L were observed, suggesting potential immune activation. Controlled in vitro studies also showed lysis of tumor cells by avelumab versus no lysis of PBMCs from five donors. These studies demonstrate the lack of any significant effect on multiple immune cell subsets, even those expressing PD-L1, following multiple cycles of avelumab. These results complement prior studies showing anti-tumor effects of avelumab and comparable levels of adverse events with avelumab versus other anti-PD-1/PD-L1 MAbs. These studies provide the rationale to further exploit the potential ADCC mechanism of action of avelumab as well as other human IgG1 checkpoint inhibitors. [ ] FIRST-IN-HUMAN PHASE I TRIAL OF A TUMOR-TARGETED CYTOKINE (NHS-IL12) IN SUBJECTS WITH METASTATIC SOLID TUMORS: The NHS-IL12 immunocytokine is composed of two IL12 heterodimers fused to the NHS76 antibody. Preclinical studies have shown that this antibody targets IL12 to regions of tumor necrosis by binding histones on free DNA fragments in these areas, resulting in enhanced antitumor activity. The objectives of this phase I study were to determine the maximum tolerated dose (MTD) and pharmacokinetics of NHS-IL12 in subjects with advanced solid tumors. Subjects (n = 59) were treated subcutaneously with NHS-IL12 in a single ascending-dose cohort followed by a multiple ascending-dose cohort. The MTD is 16.8 ug/kg. A time-dependent rise in IFNgamma and an associated rise in IL10 were observed following NHS-IL12. Of peripheral immune cell subsets evaluated, most noticeable were increases in frequencies of activated and mature natural killer (NK) cells and NKT cells. Based on T-cell receptor sequencing analysis, increases in T-cell receptor diversity and tumor-infiltrating lymphocyte density were observed after treatment where both biopsies and peripheral blood mononuclear cells were available. Although no objective tumor responses were observed, 5 subjects had durable stable disease (range, 6-30+ months). NHS-IL12 was well tolerated up to a dose of 16.8 ug/kg, which is the recommended phase II dose. Early clinical immune-related activity warrants further studies, including combination with immune checkpoint inhibitors.
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