Andrea Ponzetta

Double-negative αβ T cells (DNTαβ) are an underexplored subset of human T cells lacking CD4 and CD8 co-receptors. While extensively studied in mouse models, findings on their functional plasticity and role in tumor immunity may not fully translate to humans. Human DNTαβ cells exhibit substantial heterogeneity, but their developmental origins, antigen specificity, and functional relevance remain unclear.This project aims to systematically map human DNTαβ diversity, establish their developmental hierarchy, and determine their role in metastatic gastric cancer (GC). A combination of unique human sample collections and a novel in vitro expansion system enables us to study DNTαβ with unprecedented resolution. Using single-cell RNA and TCR sequencing, advanced flow cytometry, and functional assays, we will define the mechanisms driving DNTαβ activation, differentiation, and tumor reactivity.Our findings will clarify whether DNTαβ functionally overlap with conventional αβ T cells or represent a distinct immune subset. We will establish their antigen specificity, molecular drivers of activation, and potential interactions with the tumor microenvironment. Additionally, we will assess their prognostic value in cancer patients and explore whether specific DNTαβ subsets could be harnessed for cell-based immunotherapy or biomarker discovery.

The incidence of esophageal and gastric cancer (GEAC) in Sweden has increased over the past 40 years. There are several subtypes of GEAC, with different treatment sensitivities and prognosis. Based on current clinical practice, it is challenging to define the most effective treatment for each patient. The study of the immune response to the growing cancer has improved clinical decisions in other cancer types, but its changes during GEAC progression remain poorly understood. Therefore, this project aims to improve the clinical definition of GEAC patients by analyzing the immune response. In collaboration with doctors at Karolinska University Hospital, we will analyze primary tumor and blood from GEAC patients, to investigate whether specific immune populations can prevent, or favor, tumor formation and growth. In addition, using the latest technology, we will assess how the local (in the gastrointestinal tract) and the general (in the blood) immune response is affected by 1) presence and aggressiveness of tumor cells 2) patient treatment and 3) time after surgery. In particular, we will focus on a population of immune effectors (unconventional T cells) that have been associated with antitumor effects in other solid cancers. By understanding the mechanisms that regulate the immune response to GEAC during tumor progression and therapy, we will update the current parameters that guide clinical decisions and patient management, improving survival and patients' quality of life. For example, our data would make it possible to predict which group of GEAC patients are more likely to benefit from conventional or immune-based treatments and would provide experimental evidence to formulate innovative immunotherapies in the future. Specifically, we plan to test the antitumor potential of unconventional T cells as a novel therapeutic target for GEAC.