Independent Reproduction of the FLASH Effect on the Gastrointestinal Tract: A Multi-Institutional Comparative Study.

FLASH radiation therapy (RT) is a promising new paradigm in radiation oncology. However, a major question that remains is the robustness and reproducibility of the FLASH effect when different irradiators are used on animals or patients with different genetic backgrounds, diets, and microbiomes, all of which can influence the effects of radiation on normal tissues. To address questions of rigor and reproducibility across different centers, we analyzed independent data sets from The University of Texas MD Anderson Cancer Center and from Lausanne University (CHUV). Both centers investigated acute effects after total abdominal irradiation to C57BL/6 animals delivered by the FLASH Mobetron system. The two centers used similar beam parameters but otherwise conducted the studies independently. The FLASH-enabled animal survival and intestinal crypt regeneration after irradiation were comparable between the two centers. These findings, together with previously published data using a converted linear accelerator, show that a robust and reproducible FLASH effect can be induced as long as the same set of irradiation parameters are used.

Murine Mammary Carcinoma Induces Chronic Systemic Inflammation and Immunosuppression in BALB/c Mice.

PURPOSE: The F3II cell line is a highly invasive variant of mammary carcinoma. Although it is frequently used as a model to evaluate the efficacy of immunotherapy, its impact on the immune system remains poorly understood. The main objectives of this study were to evaluate the effects of F3II tumors on the development of chronic inflammation and to characterize tumor-associated immunosuppression. METHODS: Following the experimental implantation of F3II tumors in BALB/c mice, alterations in the liver and spleen anatomy and the numbers of circulating leukocytes, myeloid-derived suppressor cells (MDSCs), and regulatory T cells were measured using hematological techniques, histopathological analysis, and flow cytometry. The capacity of the F3II tumor-bearing mice to reject MB16F10 allogeneic tumor transplantation was also evaluated. In addition, the restoration of immune parameters in tumor-bearing mice was evaluated after standard breast cancer chemotherapy and surgical tumor excision. RESULTS: F3II tumor implantation increased the levels of chronic inflammatory markers, such as the neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios, and caused myeloid alterations, including extramedullary granulopoiesis and megakaryopoiesis, along with the recruitment of MDSCs to the spleen. Chemotherapy or surgical F3II tumor removal completely rescued the tumor-associated extramedullary granulopoiesis and megakaryopoiesis. Notably, the presence of F3II tumors reduced the capacity of BALB/c mice to reject MB16F10 allogeneic tumor transplantation. CONCLUSION: These results support the occurrence of F3II tumor-mediated immune cell dysfunction, which mimics the immune alterations characterized by chronic systemic inflammation and immunosuppression observed in breast cancer in clinical settings. Thus, the F3II tumor model is relevant for evaluating novel breast cancer immunotherapies and combinations in preclinical studies. This model could also be useful for identifying appropriate therapeutic targets and developing proof-of-concept experiments in the future.

Assessment of changes in immune status linked to COVID-19 convalescent and its clinical severity in patients and uninfected exposed relatives.

INTRODUCTION: The immune response during and after SARS-CoV-2 infection can be complex and heterogeneous, and it can be affected by the severity of the disease. It can also contribute to an unfavorable evolution and bring about short and long term effects. The aim of this study was to characterize the lymphocyte composition according to the severity of COVID-19, as well as its degree of relationship to the specific humoral response to SARS-CoV-2 in convalescents up to 106 days after the infection and in their exposed relatives. METHODS: An applied research was carried out with a cross-section analytical design, from March 11 to June 11, 2020 in Cuba. The sample consisted of 251 convalescents from COVID-19 over 18 years of age and 88 exposed controls who did not become ill. The B and T cell subpopulations, including memory T cells, as well as the relationship with the humoral immune response against SARS-CoV-2, were identified by flow cytometry and enzyme immunoassay. RESULTS: Convalescent patients, who evolved with severe forms, showed a decrease in frequency and a greater proportion of individuals with values ​​lower than the minimum normal range of B cells, CD3 + CD4 + cells and the CD4 + / CD8 + ratio, as well as a higher frequency and a greater proportion of individuals with values ​​above the normal maximum range of CD3 + CD8 + and NK cells. Convalescent patients with severe forms of COVID-19 that exhibited IgG / RBD titers ≥ 1/200 had a lower frequency of TEMRA CD8 + cells (p = 0.0128) and TEMRA CD4 + (p = 0.0068). IgG / RBD titers were positively correlated with the relative frequency of CD4 + CM T memory cells (r = 0.4352, p = 0.0018). CONCLUSIONS: The identified alterations of B and T lymphocytes suggest that convalescent patients with the severe disease could be vulnerable to infectious, autoimmune or autotinflammatory processes; therefore, these individuals need medical follow-up after recovering from the acute disease. Furthermore, the role of T cells CD4 + CM in the production of antibodies against SARS-CoV-2 is confirmed, and it is noted that the defect of memory T cells CD8 + TEMRA could contribute to the development of severe forms of COVID-19.

A single dose of SARS-CoV-2 FINLAY-FR-1A vaccine enhances neutralization response in COVID-19 convalescents, with a very good safety profile: An open-label phase 1 clinical trial.

BACKGROUND: As a first step towards a vaccine protecting COVID-19 convalescents from reinfection, we evaluated FINLAY-FR-1A vaccine in a clinical trial. METHODS: Thirty COVID-19 convalescents aged 22-57 years were studied: convalescents of mild COVID-19, asymptomatic convalescents, both with PCR-positive at the moment of diagnosis; and individuals with subclinical infection detected by viral-specific IgG. They received a single intramuscular injection of the FINLAY-FR-1A vaccine (50 µg of the recombinant dimeric receptor binding domain). The primary outcomes were safety and reactogenicity, assessed over 28 days after vaccination. The secondary outcome was vaccine immunogenicity. Humoral response at baseline and following vaccination was evaluated by ELISA and live-virus neutralization test. The effector T cellular response was also assessed. Cuban Public Registry of Clinical Trials, WHO-ICTRP: https://rpcec.sld.cu/en/trials/RPCEC00000349-En. FINDINGS: No serious adverse events were reported. Minor adverse events were found, the most common, local pain: 3 (10%) and redness: 2 (6·7%). The vaccine elicited a >21 fold increase in IgG anti-RBD antibodies 28 days after vaccination. The median of inhibitory antibody titres (94·0%) was three times greater than that of the COVID-19 convalescent panel. Virus neutralization titres higher than 1:160 were found in 24 (80%) participants. There was also an increase in RBD-specific T cells producing IFN-γ and TNF-α. INTERPRETATION: A single dose of the FINLAY-FR-1A vaccine against SARS-CoV-2 was an efficient booster of pre-existing natural immunity, with excellent safety profile. FUNDING: Partial funding for this study was received from the Project-2020-20, Fondo de Ciencia e Innovación (FONCI), Ministry of Science, Technology and the Environment, Cuba.   RESUMEN. ANTECEDENTES: Como un primer paso hacia una vacuna que proteja a los convalecientes de COVID-19 de la reinfección, evaluamos la vacuna FINLAY-FR-1A en un ensayo clínico. MÉTODOS: Se estudiaron treinta convalecientes de COVID-19 de 22 a 57 años: convalecientes de COVID-19 leve y convalecientes asintomáticos, ambos con prueba PCR positiva al momento del diagnóstico; e individuos con infección subclínica detectada por IgG específica viral. Los participantes recibieron una dosis única por vía intramuscular de la vacuna FINLAY-FR-1A (50 µg del dominio de unión al receptor recombinante dimérico del SARS CoV-2). Las variables de medida primarias fueron la seguridad y la reactogenicidad, evaluadas durante 28 días después de la vacunación. La variable secundaria, la inmunogenicidad. La respuesta humoral, al inicio del estudio y después de la vacunación, se evaluó por ELISA y mediante la prueba de neutralización del virus vivo. También se evaluó la respuesta de células T efectoras. Registro Público Cubano de Ensayos Clínicos, WHO-ICTRP: https://rpcec.sld.cu/en/trials/RPCEC00000349-En. RESULTADOS: No se reportaron eventos adversos graves. Se encontraron eventos adversos leves, los más comunes, dolor local: 3 (10%) y enrojecimiento: 2 (6·7%). La vacuna estimuló un incremento >21 veces de los anticuerpos IgG anti-RBD 28 días después de la vacunación. La mediana de los títulos de anticuerpos inhibidores (94·0%) fue aproximadamente tres veces mayor que la del panel de convalecientes de COVID-19. Se encontraron títulos de neutralización viral superiores a 1:160 en 24 (80%) de los participantes. También hubo un aumento en las células T específicas de RBD que producen IFN-γ y TNF-α. INTERPRETACIÓN: Una sola dosis de la vacuna FINLAY-FR-1A contra el SARS-CoV-2 reforzó eficazmente la inmunidad natural preexistente, con un excelente perfil de seguridad. FINANCIAMIENTO: Se recibió un financiamiento parcial del Proyecto-2020-20, Fondo de Ciencia e Innovación (FONCI), Ministerio de Ciencia, Tecnología y Medio Ambiente, Cuba.

Immunologic Response Elicited in Breast Cancer Patients Receiving a NeuGcGM3-based Vaccine as Adjuvant Therapy.

This study aimed to investigate the immunogenicity of a cancer vaccine consisting of the NeuGcGM3 ganglioside combined with the outer membrane protein complex of Neisseria meningitides to form very small size particles. The vaccine is administered together with Montanide ISA51, as adjuvant treatment for breast cancer patients. After surgical resection and standard first-line chemo/radiotherapy, breast cancer patients in stage II-III were enrolled in a phase III clinical trial and allocated into 2 strata, according to the number of positive lymph nodes [stratum I (0-3); stratum II (≥4)]. Subsequently, patients were randomly assigned to receive the vaccine or placebo. The treatment consisted of 5 vaccine doses (200 µg) every 2 weeks and thereafter monthly reimmunizations to complete 15 doses. The vaccine was well-tolerated and high titers of immunoglobulin M and immunoglobulin G anti-NeuGcGM3 antibodies were similarly detected in each stratum. Hyperimmune sera were able to specifically recognize and kill the NeuGcGM3-expressing L1210 tumor cell line, and these functional capacities were significantly associated with a better clinical outcome in patients of stratum II. Besides, postimmune sera had the capacity to revert in vitro the immunosuppression induced by NeuGcGM3, as measured by the prevention of CD4 downmodulation on human T lymphocytes. Vaccination had no impact on the frequency of regulatory T cells or circulating NK cells. This study demonstrated, for the first time, the immunogenicity of the NeuGcGM3/VSSP/Montanide ISA 51 vaccine in the adjuvant setting and describes the functionality of induced anti-NeuGcGM3 antibodies as potential surrogate biomarkers of clinical benefit.

A randomized, multicenter, placebo-controlled clinical trial of racotumomab-alum vaccine as switch maintenance therapy in advanced non-small cell lung cancer patients.

PURPOSE: Racotumomab-alum is an anti-idiotype vaccine targeting the NeuGcGM3 tumor-associated ganglioside. This clinical trial was conducted to provide a preliminary estimate of efficacy and safety of racotumomab as switch maintenance for patients with advanced non-small cell lung cancer (NSCLC). EXPERIMENTAL DESIGN: Patients with stage IIIb/IV NSCLC who have at least stable disease after first-line chemotherapy were randomized 1:1 to racotumomab-alum (5 immunizations every 2 weeks and re-immunizations every 4 weeks) or placebo. Treatment was administered beyond progressive disease, until severe performance status worsening or toxicity. At progression, only five patients per group received further anticancer therapy. The primary endpoint was overall survival (OS). RESULTS: One-hundred and seventy-six patients were randomized to racotumomab-alum (n = 87) and placebo (n = 89). Median OS was 8.23 and 6.80 months, respectively [HR, 0.63; 95% confidence interval (CI), 0.46-0.87; P = 0.004]. Median progression-free survival (PFS) in vaccinated patients was 5.33 versus 3.90 months for placebo (HR, 0.73; 95% CI 0.53-0.99; P = 0.039). The most common adverse events in the racotumomab-alum arm were burning and pain at the injection site, bone pain, and asthenia. A high antibody response of IgM and IgG isotype against the NeuGcGM3 ganglioside was obtained. Hyperimmune sera were able to specifically recognize and kill the NeuGcGM3-expressing L1210 cell line. Patients who developed anti-NeuGcGM3 antibodies capable to bind and kill ≥30% L1210 cells showed longer median survival times. CONCLUSIONS: Switch maintenance with racotumomab-alum is an effective and a well-tolerated treatment option for patients with advanced NSCLC.