Rwtc-Mbta Vaccine Induces Potent Immune Responses Against Central Nervous System Lymphoma

Our group has embarked on the exploration of a pioneering vaccine strategy comprising irradiated whole tumor cells combined with mannan-BAM, Toll-like receptor (TLR) agonists, and CD40 ligands. This multifaceted approach has demonstrated therapeutic promise in a spectrum of tumor models, including those of colon carcinoma, breast tumors, and melanoma, suggesting its potential versatility across different cancer types. Our research turns to the evaluation of the rWTC-MBTA vaccine's efficacy within lymphoma models. The central question we aim to address is whether this vaccine strategy that has shown success in other tumor types can extend its therapeutic benefits to lymphoma, including the challenging context of central nervous system (CNS) lymphoma. To investigate the efficacy of the rA20-MBTA vaccine in treating CNS lymphoma, we established an intracranial A20 lymphoma model in BALB/c mice. We intracranially injected syngeneic A20 cells (50,000 cells per mouse) into the right frontal lobe. Brain pathology was assessed five days after injection to confirm successful A20 cell implantation. Following this, mice were allocated into two groups for treatment: PBS (control) and rA20-MBTA. The rA20-MBTA vaccine was administered subcutaneously to the right flank daily for three days, with subsequent weekly administrations for a duration of four weeks. Mice were monitored until the endpoint. The vaccine of rWTC-MBTA demonstrated obvious efficacy in inhibiting tumor growth and extending survival in intracranial lymphoma model. Treatment with the rA20-MBTA vaccine significantly enhanced overall survival rates to 33.3%, compared to the control group treated with PBS (P=0.0189), underscoring the rA20-MBTA vaccine's potential as a therapeutic strategy for CNS lymphoma. To further illustrate the dynamic efficacy of the rA20-MBTA vaccine in eliciting a strong antitumor immune response against A20 lymphoma in the CNS, three specific time points were designated for collecting brains for histopathology examination: day 8 following the first vaccine cycle (days 5-7), day 15 after the second cycle (days 12-14), and day 22 subsequent to the third cycle of treatment (days 19-21). This approach was designed to closely monitor the evolution of the immune response over time. Three days post-vaccination (Day 8), HE staining of whole brain sections revealed that tumor growth patterns were similar between the control and vaccine groups, with tumors clustering and present in both the parenchyma and lateral ventricles. Infiltration of CD4+ and CD8+ T cells into the tumor microenvironment (TME) was minimal and comparable between groups. By Day 15, ten days after vaccination, notable immunological changes were observed. In the control group, tumors began to invade the meninges, as evident from gross HE staining morphology. Conversely, in the vaccinated group, tumor expansion remained confined to the parenchyma and was limited in the lateral ventricles. Although increased T cell infiltration was noted in the TME of both groups, the subtype distribution differed; the control group saw a significant rise in CD4+ T cells, whereas the vaccinated group exhibited a marked increase in CD8+ T cells, accompanied by elevated PD1 expression. Seventeen days post-vaccination (Day 22), the PBS-treated group's tumors had infiltrated the parenchyma, lateral ventricles, and meninges, maintaining a clustered morphology. In contrast, tumors in the vaccinated group began to disperse and were not observed infiltrating the lateral ventricles or meninges. T cell analysis showed a reduction in both CD4+ and CD8+ T cells in the control group. Meanwhile, the vaccinated group maintained low CD4+ expression and high CD8+ and PD1 expressions. These findings highlight the vaccine's capacity to elicit a specific and dynamic immune response against CNS lymphoma. T cell depletion experiment proved that the immune efficacy of vaccine depends on CD4/CD8. Furthermore, the assessment of antitumor cytokine levels, including IFN-γ and TNF-α, through co-culture with lymph nodes and spleen cells revealed that the rA20-MBTA vaccine not only establishes lasting immunological memory, but also elicits a stronger cytokine release response against lymphoma cells. The rWTC-MBTA showed excellent efficacy in subcutaneous lymphoma model and CNS lymphoma mouse model, and provided long-term protection to prevent relapse by inducing memory immunity.