Single-cell transcriptional analysis of malaria-specific t lymphocytes following vaccination and protection in humans

Vaccine approaches that confer durable and high-level protection against malaria infection are urgently needed. Development of next-generation vaccines is partially hindered by a limited understanding of the mechanisms underlying protective immunity. In-depth characterization of such responses will be critical in identifying immune correlates and ultimately guiding the development of next-generation vaccine strategies. The aim of this thesis was to dramatically enhance the breadth and depth of phenotypic analysis from cellular immune responses induced by two malaria vaccine candidates that have demonstrated high-level protection against CHMI: the PfSPZ Vaccine and ChAd63/MVA ME-TRAP. Single cell gene expression analysis of antigen-specific CD4+ and CD8+ T lymphocytes following vaccination and/or CHMI revealed a number of important findings. First, PfSPZ-specific CD4+ T cells from vaccinated and protected subjects in a small cohort were enriched in IL21 gene expression compared to unprotected subjects prior to challenge. Average IL21 expression per-subject correlated with antibody responses against the immunodominant CS protein. Analysis of a larger independent cohort confirmed both of these findings and provided greater power to dissect this population of IL21+ CD4+ T cells. Interestingly, these data provided evidence for a class of Th1/TFH-like cells that could potentially provide help for both CD8+ T cells and humoral responses elicited by PfSPZ vaccination. Second, analysis of CD8+ T cells from subjects vaccinated with ChAd63/MVA ME-TRAP provided the opportunity to investigate cellular immune responses that are critical for clearance of infected hepatocytes. There was evidence for multifunctional use of effector molecules in TRAP-specific CD107a+CD8+ T cells and a broad transcriptional signature of monofunctional IFNG+ CD8+ T cells, which have been previously correlated with protection induced by viral vectors. Overall, data presented in this thesis demonstrate that single-cell transcriptional analysis is a powerful tool to expand the characterization of cellular immune responses and elucidate potential correlates of protection in Phase II clinical trials.</p

Progress with viral vectored malaria vaccines: A multi-stage approach involving “unnatural immunity”

AbstractViral vectors used in heterologous prime-boost regimens are one of very few vaccination approaches that have yielded significant protection against controlled human malaria infections. Recently, protection induced by chimpanzee adenovirus priming and modified vaccinia Ankara boosting using the ME-TRAP insert has been correlated with the induction of potent CD8+ T cell responses. This regimen has progressed to field studies where efficacy against infection has now been reported. The same vectors have been used pre-clinically to identify preferred protective antigens for use in vaccines against the pre-erythrocytic, blood-stage and mosquito stages of malaria and this work is reviewed here for the first time. Such antigen screening has led to the prioritization of the PfRH5 blood-stage antigen, which showed efficacy against heterologous strain challenge in non-human primates, and vectors encoding this antigen are in clinical trials. This, along with the high transmission-blocking activity of some sexual-stage antigens, illustrates well the capacity of such vectors to induce high titre protective antibodies in addition to potent T cell responses. All of the protective responses induced by these vectors exceed the levels of the same immune responses induced by natural exposure supporting the view that, for subunit vaccines to achieve even partial efficacy in humans, “unnatural immunity” comprising immune responses of very high magnitude will need to be induced

Surgical complications and clinical outcomes after dose-escalated trimodality therapy for non-small cell lung cancer in the era of intensity-modulated radiotherapy

BackgroundTrimodality therapy (TMT) with preoperative chemoradiation followed by surgical resection is used for locally-advanced non-small-cell lung cancer (LA-NSCLC). Traditionally, preoperative radiation doses ≤54&nbsp;Gy are used due to concerns regarding excess morbidity, but little is known about outcomes and toxicities after TMT with intensity-modulated radiotherapy (IMRT) to higher doses.MethodsA retrospective analysis of patients who received planned TMT with IMRT for LA-NSCLC at Brigham and Women's Hospital/Dana-Farber Cancer Institute between 2008 and 2017 was performed. Clinical and treatment characteristics, pathologic response, and surgical toxicity were assessed. Kaplan-Meier method and log-rank test was used for survival outcomes. Cox proportional-hazards regression was used for multivariable analysis.ResultsForty-six patients received less than definitive doses of &lt;60&nbsp;Gy and 30 patients received definitive doses ≥60&nbsp;Gy. Surgical outcomes, pathologic complete response, and postoperative toxicity did not differ significantly between the groups. With median follow-up of 3.6&nbsp;years (range: 0.4-11.4), three-year locoregional recurrence-free survival (78.0% vs. 68.3%, p&nbsp;=&nbsp;0.51) and overall survival (OS) (61.0% vs. 69.4%, p&nbsp;=&nbsp;0.32) was not significantly different between patients receiving &lt;60&nbsp;Gy and ≥60&nbsp;Gy, respectively. On multivariable analysis, older age, clinical stage, and length of hospital stay (LOS) &gt;7&nbsp;days were associated with OS.ConclusionsWith IMRT, there was no increased rate of surgical complications in patients receiving higher doses of radiation. Survival outcomes or LOS did not differ based on radiation dose, but increased LOS was associated with worse OS. Larger prospective studies are needed to further examine outcomes after IMRT in patients with LA-NSCLC receiving TMT