IMMUNOREACT 9 metachronous rectal cancers have high HLA-ABC expression on healthy epithelium but a lower infiltration of CD3+ T cells than primary lesions.

Lynch syndrome is rarely associated with rectal cancer (RC) and thus, metachronous RC has been scarcely investigated. This study aimed to analyze the mucosal immune microenvironment in sporadic and metachronous RC. We analyzed the mucosal immune microenvironment in the 25 metachronous RCs present in the IMMUNOREACT 1 and 2 multicentre observational studies (624 patients).

IMMUNOREACT 8: Immune markers of local tumor spread in patients undergoing transanal excision for clinically N0 rectal cancer.

Background: Transanal excision of rectal cancer can be considered the definitive surgical treatment if the depth spread is T1 or lower, and the lesion is completely included within the resection margin. This study aims to analyze the immune microenvironment in healthy rectal mucosa as a possible predictor of tumor infiltration depth, lateral tumor spread, and recurrence of rectal cancer after transanal local excision.

Methods: This study is a subanalysis of data from the IMMUNOREACT 1 and 2 trials (NCT04915326 and NCT04917263, respectively) including all the patients who underwent transanal excision of rectal cancer.

Probing PAC1 receptor activation across species with an engineered sensor.

Class-B1 G-protein-coupled receptors (GPCRs) are an important family of clinically relevant drug targets that remain difficult to investigate via high-throughput screening and in animal models. Here, we engineered PAClight1, a novel genetically encoded sensor based on a class-B1 GPCR (the human PAC1 receptor, hmPAC1R) endowed with high dynamic range (Δ/ = 1100%), excellent ligand selectivity, and rapid activation kinetics ( = 1.15 s).

A chemogenetic approach for dopamine imaging with tunable sensitivity.

Genetically-encoded dopamine (DA) sensors enable high-resolution imaging of DA release, but their ability to detect a wide range of extracellular DA levels, especially tonic versus phasic DA release, is limited by their intrinsic affinity. Here we show that a human-selective dopamine receptor positive allosteric modulator (PAM) can be used to boost sensor affinity on-demand. The PAM enhances DA detection sensitivity across experimental preparations (in vitro, ex vivo and in vivo) via one-photon or two-photon imaging.

IMMUNOREACT 7: Regular aspirin use is associated with immune surveillance activation in colorectal cancer.

Background: Long-term daily use of aspirin reduces incidence and mortality due to colorectal cancer (CRC). This study aimed to analyze the effect of aspirin on the tumor microenvironment, systemic immunity, and on the healthy mucosa surrounding cancer.

Methods: Patients with a diagnosis of CRC operated on from 2015 to 2019 were retrospectively analyzed (METACCRE cohort).