Paul Chaplin’s research while affiliated with Bavarian Nordic and other places

In the last decade, immunotherapy has revolutionized cancer treatment. However, the lack of potent therapy-induced immune responses against solid tumors due to the immune-suppressive tumor microenvironment (TME) is still a major drawback. One approach to reprogram TME is virotherapy, which can target tumors via destruction of infected tumor cells as well as activating immune cell populations in the TME. A versatile and safe tool for virotherapy is modified vaccinia virus Ankara (MVA), which has already been approved by the FDA as a non-replicating vaccine against smallpox and monkeypox and is also in clinical trials against other infectious diseases and cancer. In the current study, we deciphered the anti-tumorigenic effect of a novel MVA vector encoding a tumor associated antigen (TAA) and the costimulatory molecules IL-12 and 4-1BBL, called MVA-TAA-4-1BBL-IL12. We could show that repetitive intratumoral (IT) injection of MVA-TAA-4-1BBL-IL12 resulted in strong tumor growth control, shrinkage and/or complete elimination of tumors and induction of tumor-specific CD8 T cell response. Furthermore, MVA-TAA-4-1BBL-IL12 treatment promoted a systemic anti-tumor immune response not only against the treated tumor but also untreated, distant tumors. Importantly, local virotherapy also resulted in the generation of tumor-specific memory response, which protected mice against local recurrence after rechallenge. As a conclusion, our findings show that MVA-TAA-4-1BBL-IL12 IT treatment induces an effective anti-tumorigenic immune response in different solid tumor models, which gives rise to long-term protection against cancer recurrence. Citation Format: Cigdem Atay Langbein, Raphael Giessel, Mahmad Ismail Housni, Kerstin Lämmermann, Barbara Bathke, André Riedl, Jürgen Hausmann, Markus Kalla, Paul Chaplin, Hubertus Hochrein, José Medina-Echeverz, Maria Hinterberger. Intratumoral administration of modified vaccinia Ankara expressing a tumor associated antigen and the costimulatory molecules IL-12 and 4-1BBL induces potent systemic long-term immune responses against murine tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB223.

The induction of antiviral innate immunity by systemic immunization with live virus can be employed to positively impact the response to therapeutic vaccination. We previously demonstrated that systemic immunization with a non-replicating MVA encoding CD40 ligand (CD40L) enhances innate immune cell activation and function, and triggers potent antitumor CD8⁺ T cell responses in different murine tumor models. Antitumor efficacy was increased when combined with tumor targeting antibodies. Here we report the development of TAEK-VAC-HerBy (TVH), a first-in-class human tumor antibody enhanced killing (TAEK) vaccine based on the non-replicating MVA-BN viral vector. It encodes the membrane bound form of human CD40L, HER2 and the transcription factor Brachyury. TVH is designed for therapeutic use in HER2- or Brachyury-expressing cancer patients in combination with tumor targeting antibodies. To preclude possible oncogenic activities in infected cells and to prevent binding of vaccine-encoded HER2 by monoclonal antibodies trastuzumab and pertuzumab, genetic modifications of HER2 were introduced in the vaccine. Brachyury was genetically modified to prevent nuclear localization of the protein thereby inhibiting its transcriptional activity. CD40L encoded in TVH enhanced human leukocyte activation and cytokine secretion in vitro. Lastly, TVH intravenous administration to non-human primates was proven immunogenic and safe in a repeat-dose toxicity study. Nonclinical data presented here highlight TVH as a first-in-class immunotherapeutic vaccine platform currently under clinical investigation.

Background The ongoing monkeypox outbreak, a WHO-declared PHEIC, requires fast and broad rollout of MVA-BN vaccinations among risk groups. An initial single-dose strategy, followed by a delayed second dose beyond the approved 4-week interval, could help managing tight vaccine resources. Methods Bavarian Nordic has run a study in vaccinia-naïve participants, randomized to receive either 1 MVA-BN vaccination (N = 181) or 2 MVA-BN vaccinations 4 weeks apart (N = 183). Of note, this study also evaluated participants with prior smallpox vaccination, who received 1 MVA-BN boost (N = 200). Subsets of approximately 75 participants of the vaccinia-naïve subjects having received either 1 or 2 doses of the vaccine were administered an MVA-BN boost 2 years later. Neutralizing antibodies (nAb) were measured using Vaccinia PRNT. Results The 1xMVA-BN and 2xMVA-BN groups responded as expected to the primary regimen, with modest increases in nAb GMTs at Week 2 (5.1 and 4.8, respectively) that further increased at Week 4 (7.2 and 7.5). Two weeks after the second primary vaccination (at Week 6) (2xMVA-BN) nAb GMTs peaked (45.6) before stabilizing at Week 8 (34.0). In both the 1x and 2xMVA-BN groups, the nAb levels were near baseline 2 years after primary vaccination. After the MVA-BN boost at 2 years, both groups exhibited rapid anamnestic responses with nAb GMTs that peaked 2 weeks post-boost (80.7 and 125.3), at higher levels than those observed at any timepoint following primary vaccination, remaining elevated at 6 months post-boost (25.6 and 49.3). These anamnestic responses support the presence of durable immunological memory in both groups. No safety concerns were identified and the most common adverse event following a 2-year MVA-BN boost was injection site erythema in 82.2% of participants. Conclusion A single dose of MVA-BN elicits a durable memory immune response for at least 2 years. Similarly, high nAb responses following a boost dose among subjects in the initial 1xMVA-BN or 2xMVA-BN groups indicate that the approved 4-week interval of the two-dose regimen could optionally be extended up to at least 2 years. NCT00316524 and NCT00686582 Disclosures Heinz Weidenthaler, MD, Bavarian Nordic GmbH: Employee and received warrants Florian Lienert, PhD, Bavarian Nordic GmbH: employee Employee and received warrants Daniela Reichhardt, PhD, Bavarian Nordic A/S: employee Employee and received warrants Darja Schmidt, Dr, Bavarian Nordic GmbH: Employee and received warrants Günter Silbernagl, MSc, Bavarian Nordic: Employed|Bavarian Nordic GmbH: employee Employee and received warrants Paul Chaplin, PhD, Bavarian Nordic A/S: employee (CEO)|Bavarian Nordic A/S: Stocks/Bonds.

Background Though Modified Vaccinia Ankara - Bavarian Nordic (MVA-BN®). vaccination is approved for smallpox and monkeypox prevention, immunological persistence and booster effects remain undescribed. Methods Participants naïve to smallpox vaccination were randomized to 1 dose MVA-BN (1×MVA, N = 181), 2 doses MVA-BN (2×MVA, N = 183), or placebo (N = 181). Participants with previous smallpox vaccination received 1 MVA-BN booster (HSPX+, N = 200). Subsets of the formerly naïve groups (∼75 each) received an MVA-BN booster 2 years later. Results Neutralizing antibody (nAb) geometric mean titers (GMTs) increased from 1.1 (baseline, both naïve groups) to 7.2 and 7.5 (Week 4, 1×MVA and 2×MVA, respectively), and further to 45.6 (Week 6, 2×MVA after second vaccination). In HSPX+, nAb GMT rapidly increased from 21.6 (baseline) to 175.1 (Week 2). At 2 years, GMTs for 1×MVA, 2×MVA, and HSPX+ were 1.1, 1.3, and 10.3, respectively. After boosting in the previously naïve groups, nAb GMTs increased rapidly in 2 weeks to 80.7 (1×MVA) and 125.3 (2×MVA), higher than after primary vaccination and comparable to boosted HSPX+ subjects. Six months after boosting, GMTs were 25.6 (1×MVA) and 49.3 (2×MVA). No safety concerns were identified. Conclusion Anamnestic responses without sustained high nAb titers support presence of durable immunological memory following MVA-BN immunization.

Respiratory syncytial virus (RSV) causes a respiratory disease with a potentially fatal outcome especially in infants and elderly individuals. Several vaccines failed in pivotal clinical trials, and to date, no vaccine against RSV has been licensed. We have developed an RSV vaccine based on the recombinant Modified Vaccinia Virus Ankara-BN® (MVA-RSV), containing five RSV-specific antigens that induced antibody and T-cell responses, which is currently tested in clinical trials. Here, the immunological mechanisms of protection were evaluated to determine viral loads in lungs upon vaccination of mice with MVA-RSV followed by intranasal RSV challenge. Depletion of CD4 or CD8 T cells, serum transfer, and the use of genetically engineered mice lacking the ability to generate either RSV-specific antibodies (T11µMT), the IgA isotype (IgA knockout), or CD8 T cells (β2M knockout) revealed that complete protection from RSV challenge is dependent on CD4 and CD8 T cells as well as antibodies, including IgA. Thus, MVA-RSV vaccination optimally protects against RSV infection by employing multiple arms of the adaptive immune system.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a worldwide pandemic. Here, we present non-human primate immunogenicity and protective efficacy data generated with the capsid virus-like particle (cVLP)-based vaccine ABNCoV2 that has previously demonstrated immunogenicity in mice. In rhesus macaques, a single vaccination with either 15 or 100 μg ABNCoV2 induced binding and neutralizing antibodies in a dose-dependent manner, at levels comparable to those measured in human convalescents. A second vaccine administration led to a >50-fold increase in neutralizing antibodies, with 2-log higher mean levels in the 100-μg ABNCoV2 group compared with convalescent samples. Upon SARS-CoV-2 challenge, a significant reduction in viral load was observed for both vaccine groups relative to the challenge control group, with no evidence of enhanced disease. Remarkably, neutralizing antibody titers against an original SARS-CoV-2 isolate and against variants of concern were comparable, indicating a potential for broad protection afforded by ABNCoV2, which is currently in clinical testing.

Background There are limited data regarding immunological correlates of protection for the modified vaccinia Ankara (MVA) smallpox vaccine. Methods Five hundred twenty-three vaccinia-naïve subjects were randomized to receive two vaccine doses, either lyophilized MVA subcutaneously (SC), liquid MVA SC or liquid MVA intradermally (ID) 28 days apart. For a subset of subjects, antibody-dependent cellular cytotoxicity (ADCC), IFN- γ release enzyme-linked immunospot (ELISPOT), and protein microarray antibody-binding assays were conducted. Protein microarray responses were assessed for correlations with PRNT, enzyme-linked immunosorbent assay (ELISA), ADCC and ELISPOT results. Results MVA elicited significant microarray antibody responses to 15 of 224 antigens, mostly virion membrane proteins, at day 28 or 42, particularly, WR113/D8L and WR101H3L. In the Liquid-SC group, responses to nine antigens, including WR113/D8L and WR101/H3L, correlated with PRNT results. Three correlated for the Liquid-ID group. No significant correlations were observed with ELISPOT responses. In the Liquid-ID group, WR052/F13L, a membrane glycoprotein, correlated with ADCC responses. Conclusions MVA elicited antibodies to fifteen vaccinia strain antigens representing virion membrane. Antibody responses to two proteins strongly increased and significantly correlated with increases in PRNT. Responses to these proteins are potential correlates of protection and may serve as immunogens for future vaccine development.

Background Human cancers are extraordinarily heterogeneous in terms of tumor antigen expression, immune infiltration and composition. A common feature, however, is the host′s inability to mount potent immune responses that prevent tumor growth effectively. Often, naturally primed CD8 ⁺ T cells against solid tumors lack adequate stimulation and efficient tumor tissue penetration due to an immune hostile tumor microenvironment. Methods To address these shortcomings, we cloned tumor-associated antigens (TAA) and the immune-stimulatory ligand 4-1BBL into the genome of modified vaccinia Ankara (MVA) for intratumoral virotherapy. Results Local treatment with MVA-TAA-4-1BBL resulted in control of established tumors. Intratumoral injection of MVA localized mainly to the tumor with minimal leakage to the tumor-draining lymph node. In situ infection by MVA-TAA-4-1BBL triggered profound changes in the tumor microenvironment, including the induction of multiple proinflammatory molecules and immunogenic cell death. These changes led to the reactivation and expansion of antigen-experienced, tumor-specific cytotoxic CD8 ⁺ T cells that were essential for the therapeutic antitumor effect. Strikingly, we report the induction of a systemic antitumor immune response including tumor antigen spread by local MVA-TAA-4-1BBL treatment which controlled tumor growth at distant, untreated lesions and protected against local and systemic tumor rechallenge. In all cases, 4-1BBL adjuvanted MVA was superior to MVA. Conclusion Intratumoral 4-1BBL-armed MVA immunotherapy induced a profound reactivation and expansion of potent tumor-specific CD8 ⁺ T cells as well as favorable proinflammatory changes in the tumor microenvironment, leading to elimination of tumors and protective immunological memory.

Background Virus-based vaccines and appropriate costimulation potently enhance antigen-specific T cell immunity against cancer. In the present study, we exploit both innate and adaptive immune responses triggered by a novel recombinant modified vaccinia virus Ankara (rMVA) encoding a Tumor-Associated Antigen (TAA) and the costimulatory CD40L against solid tumors in combination regimes to overcome tumor-induced resistance to immunotherapy. Material and Methods Subcutaneous murine tumors were induced in C57BL/6 or Balb/c mice using syngeneic tumor cell lines. When tumors were established (60–80 mm ³ ) mice were intravenously injected with rMVA-CD40L. Tumor growth monitoring and immune cell analysis was performed. Results Therapeutic treatment with rMVA-CD40L resulted in the control of established tumors in several independent tumor models. This antitumor effect was based on the generation of non-exhausted, systemic tumor-specific cytotoxic CD8 ⁺ T cells that was essential for therapeutic efficacy. Strikingly, rMVA-CD40L also induced strong NK cell activation and enhanced cytotoxicity. Moreover, the combination of rMVA-CD40L and tumor targeting antibodies resulted in increased therapeutic antitumor efficacy. This therapeutic combination relied on Fcγ receptor-expressing immune cells as well as on NK cells. Conclusion We describe a novel and translationally relevant therapeutic synergy between viral vaccination and CD40L costimulation. We show strengthened antitumor immune responses when both rMVA-CD40L-induced innate and adaptive immune mechanisms are exploited by combining immunotherapeutic regimes, such as TAA targeting antibodies. This finding could have a direct positive impact in therapeutic regimens where TAA targeting antibodies could be employed. Disclosure Information M. Hinterberger: A. Employment (full or part-time); Significant; Bavarian Nordic. J. Medina-Echeverz: A. Employment (full or part-time); Significant; Bavarian Nordic. M. Testori: A. Employment (full or part-time); Significant; Bavarian Nordic. M. Geiger: A. Employment (full or part-time); Significant; Bavarian Nordic. R. Giessel: A. Employment (full or part-time); Significant; Bavarian Nordic. B. Bathke: A. Employment (full or part-time); Significant; Bavarian Nordic. R. Kassub: A. Employment (full or part-time); Significant; Bavarian Nordic. F. Gräbnitz: A. Employment (full or part-time); Significant; Bavarian Nordic. G. Fiore: A. Employment (full or part-time); Significant; Bavarian Nordic. S. Wennier: A. Employment (full or part-time); Significant; Bavarian Nordic. P. Chaplin: A. Employment (full or part-time); Significant; Bavarian Nordic. M. Suter: A. Employment (full or part-time); Significant; Bavarian Nordic. H. Hochrein: A. Employment (full or part-time); Significant; Bavarian Nordic. H. Lauterbach: A. Employment (full or part-time); Significant; Bavarian Nordic.