Immune Checkpoint VISTA Doubles as a Growth Engine Inside Mesothelioma Cells

Mesothelioma has long been one of oncology’s most stubborn adversaries, an aggressive cancer of the lining of the chest and abdomen driven overwhelmingly by asbestos exposure and notoriously resistant to chemotherapy, surgery and radiotherapy. Now researchers in Japan have uncovered a surprising double life for a well-known immune checkpoint molecule, showing that VISTA, a protein long studied for its ability to suppress T cell activity, also acts directly inside tumour cells to fuel their proliferation. The discovery, published in the British Journal of Cancer by a team at the Aichi Cancer Center Research Institute and Nagoya University, suggests that the molecule could serve as a subtype-specific therapeutic target in a disease where treatment options remain painfully limited.

The molecule at the centre of the story, V-domain Ig suppressor of T cell activation, or VISTA, belongs to the B7 family of immune-regulatory ligands. Immunologists first characterised it as a negative regulator of T cell responses, and subsequent work established it as a bona fide immune checkpoint alongside better-known targets such as PD-1 and CTLA-4. In many cancers, high VISTA expression has been associated with immunosuppressive tumour microenvironments and, in several tumour types, with poorer clinical outcomes. Immune checkpoint inhibitors that unleash T cells have already transformed the treatment landscape for mesothelioma: the CheckMate 743 trial demonstrated that first-line nivolumab plus ipilimumab improves survival in unresectable malignant pleural mesothelioma compared with platinum-based chemotherapy. Yet responses are far from universal, and the disease continues to claim tens of thousands of lives globally each year, a burden compounded by incomplete mortality data and continuing occupational asbestos exposure in many countries.

What makes the new study striking is that it reframes VISTA not primarily as a saboteur of anti-tumour immunity but as an intrinsic growth driver within the cancer cells themselves. The team began by mining The Cancer Genome Atlas mesothelioma cohort, which revealed that VISTA and its B7-family relative B7-H3 are both highly expressed in mesothelioma. Intriguingly, their expression patterns diverged along histological lines: VISTA levels correlated positively with genes characteristic of the epithelioid subtype, the most common form of the disease, whereas B7-H3 expression tracked with genes enriched in sarcomatoid tumours, the more aggressive and treatment-resistant variant. This subtype-specific patterning hinted that the two molecules might play distinct biological roles rather than functioning as interchangeable markers of immune evasion.

To test whether VISTA does anything functional in mesothelioma cells, the researchers turned to cell lines and genetic manipulation. When they overexpressed VISTA, the mesothelioma cells proliferated more vigorously. When they knocked the gene down, proliferation dropped markedly, an effect that held both in vitro and in a mouse xenograft model, where silencing VISTA significantly suppressed tumour growth in vivo. These are not trivial results. They demonstrate that a molecule celebrated for dampening immune attacks is simultaneously operating as an oncogenic asset inside the tumour, promoting cell division through mechanisms that have nothing to do with evading T cells.

Uncovering those mechanisms required two complementary high-throughput approaches. First, the team performed immunoprecipitation followed by mass spectrometry to catalogue the proteins that physically associate with VISTA inside mesothelioma cells. The proteomic profiling revealed interactions with cell adhesion molecules and with intracellular signalling proteins, most notably receptor-interacting serine/threonine-protein kinase 1, or RIPK1. RIPK1 is a fascinating and clinically scrutinised node in cellular signalling, sitting at the crossroads of inflammation and cell death pathways and increasingly regarded as a druggable target in its own right. Its presence in a VISTA-associated complex suggests that the checkpoint protein is wired into core signalling circuitry that governs cell survival and proliferation, rather than merely decorating the cell surface for immunological purposes.

Second, RNA sequencing of cells with altered VISTA levels mapped the downstream transcriptional consequences. The analysis showed enrichment of TNF signalling among the genes whose expression changed, pointing to a reprogramming of inflammatory response pathways within the tumour cells. Functional assays then delivered the mechanistic punchline: VISTA expression enhanced phosphorylation of AKT, also known as protein kinase B, a central hub of the PI3K signalling cascade that promotes cell growth, survival and proliferation in many cancers. Together, the proteomic and transcriptomic data sketch a coherent model in which VISTA, through its interactions with adhesion molecules and RIPK1 and its modulation of TNF-related programmes, amplifies AKT-dependent signalling that drives mesothelioma cells to divide.

The concept of tumour-intrinsic immune checkpoint signalling is not entirely without precedent. PD-L1, the ligand for PD-1, has been shown to carry an intracellular signalosome in cancer cells that can influence autonomous growth and resistance to therapy, and recent work has implicated VISTA itself in intrinsic growth regulation in other malignancies, including a report that a short intracellular motif of VISTA can block growth receptor signalling in certain cancer cells. The mesothelioma findings extend this emerging paradigm and add an important nuance: in this disease, VISTA appears to do the opposite, actively promoting proliferation. The directionality of the effect may depend on cellular context, downstream partners or the intracellular motifs engaged, questions that will likely occupy the field as the biology is dissected further.

Therapeutically, the implications are considerable. If VISTA drives tumour growth through cell-autonomous signalling, then blocking it could deliver a double blow, simultaneously releasing the brakes on anti-tumour T cells and starving the cancer cells of an internal growth signal. Several anti-VISTA antibodies are already in clinical development, and imaging studies using radiolabelled anti-VISTA agents are helping to characterise the target in patients. The new data argue that mesothelioma, particularly the epithelioid subtype in which VISTA expression is enriched, should be considered a priority indication for such agents. They also raise the possibility of combination strategies, pairing VISTA blockade with existing checkpoint inhibitors or with agents that target the AKT pathway or RIPK1 signalling, though such hypotheses will need to be tested rigorously in preclinical and clinical settings.

Caveats remain, as they always do in translational research. The study relies on cell lines, xenografts and retrospective analysis of a public genomic dataset; whether VISTA expression predicts outcome in mesothelioma patients, and whether pharmacological blockade of the molecule slows tumours in humans, are questions that only clinical trials can answer. The precise molecular choreography linking VISTA, RIPK1, TNF signalling and AKT phosphorylation also awaits detailed structural and biochemical definition. Moreover, VISTA is known to bind ligands such as PSGL-1 and VSIG-3 in an acidic, pH-sensitive manner, and the interplay between these extracellular interactions and the intracellular signalling uncovered here is an open puzzle.

Even so, the study adds a compelling new character to the mesothelioma story and exemplifies a broader shift in immuno-oncology thinking: checkpoint molecules are not merely handles for immune manipulation but signalling platforms in their own right, embedded in the growth machinery of the tumours that display them. For a cancer that has seen only incremental therapeutic progress for decades, the identification of a druggable molecule that is both highly expressed and functionally required for tumour proliferation is the kind of finding that can reshape research agendas. As clinical programs against VISTA mature, mesothelioma patients, who have waited a long time for genuinely new options, may finally stand to benefit from a target that works on both sides of the tumour’s defences.

Subject of Research: Tumour-intrinsic proliferative signalling by the immune checkpoint molecule VISTA in mesothelioma

Article Title: VISTA drives tumour-intrinsic proliferation in mesothelioma cells

Article References: VISTA drives tumour-intrinsic proliferation in mesothelioma cells. (n.d.). https://doi.org/10.1038/s41416-026-03639-z

Image Credits: AI Generated

DOI: 10.1038/s41416-026-03639-z

Keywords: mesothelioma, VISTA, immune checkpoint, B7-H3, RIPK1, AKT signalling, TNF signalling, tumour-intrinsic proliferation, TCGA, xenograft, immunotherapy, British Journal of Cancer