The Role of the Conserved Residues His-246, His-199, and Tyr-255 in the Catalysis of Catechol 2,3-Dioxygenase from Pseudomonas stutzeri OX1

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Phase I trial of viral vector based personalized vaccination elicits robust neoantigen specific antitumor T cell responses

Purpose: Personalized vaccines targeting multiple neoantigens (nAgs) are a promising strategy for eliciting a diversified antitumor T cell response to overcome tumor heterogeneity. NOUS-PEV is a vector based personalized vaccine, expressing 60 nAgs and consists of priming with a non-human Great Ape Adenoviral vector (GAd20) followed by boosts with Modified Vaccinia Ankara (MVA). Here, we report data of a phase Ib trial of NOUS-PEV in combination with pembrolizumab in treatment naïve metastatic melanoma patients (NCT04990479). Experimental Design: The feasibility of this approach was demonstrated by producing, releasing and administering to six patients 11 out of 12 vaccines within 8 weeks from biopsy collection to GAd20 administration. Results: The regimen was safe, with no treatment-related serious adverse events observed and mild vaccine-related reactions. Vaccine immunogenicity was demonstrated in all evaluable patients receiving the prime/boost regimen, with detection of robust neoantigen specific immune responses to multiple neoantigens comprising both CD4 and CD8 T cells. Expansion and diversification of vaccine-induced TCR clonotypes was observed in the post-treatment biopsies of patients with clinical response providing evidence of tumor infiltration by vaccine-induced neoantigen-specific T cell. Conclusions: These findings indicate the ability of NOUS-PEV to amplify and broaden the repertoire of tumor reactive T cells to empower a diverse, potent and durable antitumor immune response. Finally, a gene signature indicative for reduced presence of activated T cells together with very poor expression of the antigen processing machinery (APM) genes has been identified in pre-treatment biopsies as a potential biomarker of resistance to the treatment

Protective CD8+ T-cell immunity to human malaria induced by chimpanzee adenovirus-MVA immunisation.

Induction of antigen-specific CD8(+) T cells offers the prospect of immunization against many infectious diseases, but no subunit vaccine has induced CD8(+) T cells that correlate with efficacy in humans. Here we demonstrate that a replication-deficient chimpanzee adenovirus vector followed by a modified vaccinia virus Ankara booster induces exceptionally high frequency T-cell responses (median >2400 SFC/10(6) peripheral blood mononuclear cells) to the liver-stage Plasmodium falciparum malaria antigen ME-TRAP. It induces sterile protective efficacy against heterologous strain sporozoites in three vaccinees (3/14, 21%), and delays time to patency through substantial reduction of liver-stage parasite burden in five more (5/14, 36%), P=0.008 compared with controls. The frequency of monofunctional interferon-γ-producing CD8(+) T cells, but not antibodies, correlates with sterile protection and delay in time to patency (P(corrected)=0.005). Vaccine-induced CD8(+) T cells provide protection against human malaria, suggesting that a major limitation of previous vaccination approaches has been the insufficient magnitude of induced T cells

Clinical Assessment of a Recombinant Simian Adenovirus ChAd63: A Potent New Vaccine Vector

Background. Vaccine development in human Plasmodium falciparum malaria has been hampered by the exceptionally high levels of CD8+ T cells required for efficacy. Use of potently immunogenic human adenoviruses as vaccine vectors could overcome this problem, but these are limited by preexisting immunity to human adenoviruses

Human vaccination against RH5 induces neutralizing antimalarial antibodies that inhibit RH5 invasion complex interactions.

The development of a highly effective vaccine remains a key strategic goal to aid the control and eventual eradication of Plasmodium falciparum malaria. In recent years, the reticulocyte-binding protein homolog 5 (RH5) has emerged as the most promising blood-stage P. falciparum candidate antigen to date, capable of conferring protection against stringent challenge in Aotus monkeys. We report on the first clinical trial to our knowledge to assess the RH5 antigen - a dose-escalation phase Ia study in 24 healthy, malaria-naive adult volunteers. We utilized established viral vectors, the replication-deficient chimpanzee adenovirus serotype 63 (ChAd63), and the attenuated orthopoxvirus modified vaccinia virus Ankara (MVA), encoding RH5 from the 3D7 clone of P. falciparum. Vaccines were administered i.m. in a heterologous prime-boost regimen using an 8-week interval and were well tolerated. Vaccine-induced anti-RH5 serum antibodies exhibited cross-strain functional growth inhibition activity (GIA) in vitro, targeted linear and conformational epitopes within RH5, and inhibited key interactions within the RH5 invasion complex. This is the first time to our knowledge that substantial RH5-specific responses have been induced by immunization in humans, with levels greatly exceeding the serum antibody responses observed in African adults following years of natural malaria exposure. These data support the progression of RH5-based vaccines to human efficacy testing

A third generation vaccine for human visceral leishmaniasis and post kala azar dermal leishmaniasis : First-in-human trial of ChAd63-KH

BACKGROUND: Visceral leishmaniasis (VL or kala azar) is the most serious form of human leishmaniasis, responsible for over 20,000 deaths annually, and post kala azar dermal leishmaniasis (PKDL) is a stigmatizing skin condition that often occurs in patients after successful treatment for VL. Lack of effective or appropriately targeted cell mediated immunity, including CD8+ T cell responses, underlies the progression of VL and progression to PKDL, and can limit the therapeutic efficacy of anti-leishmanial drugs. Hence, in addition to the need for prophylactic vaccines against leishmaniasis, the development of therapeutic vaccines for use alone or in combined immuno-chemotherapy has been identified as an unmet clinical need. Here, we report the first clinical trial of a third-generation leishmaniasis vaccine, developed intentionally to induce Leishmania-specific CD8+ T cells. METHODS: We conducted a first-in-human dose escalation Phase I trial in 20 healthy volunteers to assess the safety, tolerability and immunogenicity of a prime-only adenoviral vaccine for human VL and PKDL. ChAd63-KH is a replication defective simian adenovirus expressing a novel synthetic gene (KH) encoding two Leishmania proteins KMP-11 and HASPB. Uniquely, the latter was engineered to reflect repeat domain polymorphisms and arrangements identified from clinical isolates. We monitored innate immune responses by whole blood RNA-Seq and antigen specific CD8+ T cell responses by IFNγ ELISPOT and intracellular flow cytometry. FINDINGS: ChAd63-KH was safe at intramuscular doses of 1x1010 and 7.5x1010 vp. Whole blood transcriptomic profiling indicated that ChAd63-KH induced innate immune responses characterized by an interferon signature and the presence of activated dendritic cells. Broad and quantitatively robust CD8+ T cell responses were induced by vaccination in 100% (20/20) of vaccinated subjects. CONCLUSION: The results of this study support the further development of ChAd63-KH as a novel third generation vaccine for VL and PKDL. TRIAL REGISTRATION: This clinical trial (LEISH1) was registered at EudraCT (2012-005596-14) and ISRCTN (07766359)

Prime-Boost Immunization with Adenoviral and Modified Vaccinia Virus Ankara Vectors Enhances the Durability and Polyfunctionality of Protective Malaria CD8+ T-Cell Responses

Protection against liver-stage malaria relies on the induction of high frequencies of antigen-specific CD8+ T cells. We have previously reported high protective levels against mouse malaria, albeit short-lived, by a single vaccination with adenoviral vectors coding for a liver-stage antigen (ME.TRAP). Here, we report that prime-boost regimens using modified vaccinia virus Ankara (MVA) and adenoviral vectors encoding ME.TRAP can enhance both short- and long-term sterile protection against malaria. Protection persisted for at least 6 months when simian adenoviruses AdCh63 and AdC9 were used as priming vectors. Kinetic analysis showed that the MVA boost made the adenoviral-primed T cells markedly more polyfunctional, with the number of gamma interferon (INF-gamma), tumor necrosis factor alpha (TNF-alpha), and interleukin-2 (IL-2) triple-positive and INF-gamma and TNF-alpha double-positive cells increasing over time, while INF-gamma single-positive cells declined with time. However, IFN-gamma production prevailed as the main immune correlate of protection, while neither an increase of polyfunctionality nor a high integrated mean fluorescence intensity (iMFI) correlated with protection. These data highlight the ability of optimized viral vector prime-boost regimens to generate more protective and sustained CD8+ T-cell responses, and our results encourage a more nuanced assessment of the importance of inducing polyfunctional CD8(+) T cells by vaccination

Prime-Boost Immunization with Adenoviral and Modified Vaccinia Virus Ankara Vectors Enhances the Durability and Polyfunctionality of Protective Malaria CD8+ T-Cell Responses▿ †

Protection against liver-stage malaria relies on the induction of high frequencies of antigen-specific CD8+ T cells. We have previously reported high protective levels against mouse malaria, albeit short-lived, by a single vaccination with adenoviral vectors coding for a liver-stage antigen (ME.TRAP). Here, we report that prime-boost regimens using modified vaccinia virus Ankara (MVA) and adenoviral vectors encoding ME.TRAP can enhance both short- and long-term sterile protection against malaria. Protection persisted for at least 6 months when simian adenoviruses AdCh63 and AdC9 were used as priming vectors. Kinetic analysis showed that the MVA boost made the adenoviral-primed T cells markedly more polyfunctional, with the number of gamma interferon (INF-γ), tumor necrosis factor alpha (TNF-α), and interleukin-2 (IL-2) triple-positive and INF-γ and TNF-α double-positive cells increasing over time, while INF-γ single-positive cells declined with time. However, IFN-γ production prevailed as the main immune correlate of protection, while neither an increase of polyfunctionality nor a high integrated mean fluorescence intensity (iMFI) correlated with protection. These data highlight the ability of optimized viral vector prime-boost regimens to generate more protective and sustained CD8+ T-cell responses, and our results encourage a more nuanced assessment of the importance of inducing polyfunctional CD8+ T cells by vaccination