A phase 2 study of a brachyury-targeting vaccine in combination with radiation therapy for the treatment of advanced chordoma.

BACKGROUND: This was a single-arm, phase 2 clinical trial of Bavarian Nordic (BN)-Brachyury vaccine plus radiotherapy (RT) designed to determine the objective response rate (ORR), progression-free survival (PFS), and safety of the combination in chordoma. METHODS: A total of 29 adult patients with advanced chordoma were treated with two subcutaneous priming vaccine doses of modified vaccinia Ankara-Bavarian Nordic (MVA-BN)-Brachyury and one vaccine dose of fowlpox virus (FPV)-Brachyury before RT. After RT, booster vaccinations were given with FPV-Brachyury every 4 weeks for 4 doses, then every 12 weeks (week 110). A minimum RT dose of >8 Gy in one fraction for each target was required. Response was evaluated by modified Response Evaluation Criteria in Solid Tumors 1.1 (mRECIST), where only radiated lesions were considered targets, and by standard RECIST 1.1 in a subset of patients. RESULTS: Two of 26 evaluable patients experienced durable partial response (PR) (ORR of 7.7%; 90% confidence interval [CI], 2.6-20.8]) by mRECIST 1.1. A total of 21 patients (80.8%; 90% CI, 65.4-90.3) had stable disease, and three patients (11.5%; 90% CI, 4.7-25.6) had progressive disease as best response per mRECIST 1.1. Median PFS was not reached during the study. CONCLUSIONS: This trial confirms the safety of BN-Brachyury and RT. Although the study did not meet the predefined study goal of four responses in 29 patients, we did observe two PRs and a PFS of greater than 2 years. For a vaccine-based study in chordoma, an ultra-rare disease where response rates are low, a randomized study or novel trial designs may be required to confirm activity.

Phase 1 open-label trial of intravenous administration of MVA-BN-brachyury-TRICOM vaccine in patients with advanced cancer.

BACKGROUND: MVA-BN-brachyury-TRICOM is a recombinant vector-based therapeutic cancer vaccine designed to induce an immune response against brachyury. Brachyury, a transcription factor overexpressed in advanced cancers, has been associated with treatment resistance, epithelial-to-mesenchymal transition, and metastatic potential. MVA-BN-brachyury-TRICOM has demonstrated immunogenicity and safety in previous clinical trials of subcutaneously administered vaccine. Preclinical studies have suggested that intravenous administration of therapeutic vaccines can induce superior CD8+ T cell responses, higher levels of systemic cytokine release, and stronger natural killer cell activation and proliferation. This is the first-in-human study of the intravenous administration of MVA-BN-brachyury-TRICOM. METHODS: Between January 2020 and March 2021, 13 patients were treated on a phase 1, open-label, 3+3 design, dose-escalation study at the National Institutes of Health Clinical Center. The study population was adults with advanced solid tumors and was enriched for chordoma, a rare sarcoma of the notochord that overexpresses brachyury. Vaccine was administered intravenously at three DLs on days 1, 22, and 43. Blood samples were taken to assess drug pharmacokinetics and immune activation. Imaging was conducted at baseline, 1 month, and 3 months post-treatment. The primary endpoint was safety and tolerability as determined by the frequency of dose-limiting toxicities; a secondary endpoint was determination of the recommended phase 2 dose. RESULTS: No dose-limiting toxicities were observed and no serious adverse events were attributed to the vaccine. Vaccine-related toxicities were consistent with class profile (ie, influenza-like symptoms). Cytokine release syndrome up to grade 2 was observed with no adverse outcomes. Dose-effect trend was observed for fever, chills/rigor, and hypotension. Efficacy analysis of objective response rate per RECIST 1.1 at the end of study showed one patient with a partial response, four with stable disease, and eight with progressive disease. Three patients with stable disease experienced clinical benefit in the form of improvement in pain. Immune correlatives showed T cell activation against brachyury and other tumor-associated cascade antigens. CONCLUSIONS: Intravenous administration of MVA-BN-brachyury-TRICOM vaccine was safe and tolerable. Maximum tolerated dose was not reached. The maximum administered dose was 109 infectious units every 3 weeks for three doses. This dose was selected as the recommended phase 2 dose. TRIAL REGISTRATION NUMBER: NCT04134312.

Safety and immunogenicity of novel modified vaccinia Ankara-vectored RSV vaccine: A randomized phase I clinical trial.

Respiratory disease caused by RSV infection is recognized as a severe public health issue in infants, young children and elderly with no specific treatment option. Vaccination may be the most effective strategy to combat this highly infectious virus although no vaccine has been approved. The novel vaccine candidate MVA-BN-RSV encodes RSV surface proteins F and G (subtypes A, B) as well as internal proteins N and M2 in the MVA-BN viral vector backbone to provide broad protection against RSV. This was a first in human study to investigate safety, reactogenicity and immunogenicity of MVA-BN-RSV. Sixty-three participants were allocated to 3 groups: adult (18-49 years) low (1 × 107 TCID50) or high (1 × 108 TCID50) dose and older adult (50-65 years) high dose. Participants in each group were randomized in a 6:1 ratio to receive 2 doses of MVA-BN-RSV or placebo 4 weeks apart and were monitored for 30 weeks. All participants completed the study, receiving both doses. No serious AEs or AEs of special interest were reported. The most common AEs were injection site pain (56% in the combined high dose groups, 17% in the low dose group). MVA-BN-RSV induced robust T cell responses covering all 5 inserts with fold increases ranging from 1.8 to 3.8. Higher and broader responses were observed in the high dose groups (83% responders to at least 3 peptide pools in the combined high dose groups compared to 63% in the low dose group). Moderate but consistent humoral responses were observed against A and B RSV subtypes (up to approximately 2-fold increases in the high dose groups). No differences were observed between the adult and the older adult groups in safety, reactogenicity or immunogenicity. The study demonstrated that the well tolerated MVA-BN-RSV vaccine candidate induces broad cellular and humoral immune responses, warranting further development.