"Wnt/β-Catenin in GIST"-Letter

Tumor genotype, location, and malignant potential shape the immunogenicity of primary untreated gastrointestinal stromal tumors

Intratumoral immune infiltrate was recently reported in gastrointestinal stromal tumors (GISTs). However, the tumor-intrinsic factors that dictate GIST immunogenicity are still largely undefined. To shed light on this issue, a large cohort (82 samples) of primary untreated GISTs, representative of major clinicopathological variables, was investigated by an integrated immunohistochemical, transcriptomic, and computational approach. Our results indicate that tumor genotype, location, and malignant potential concur to shape the immunogenicity of primary naive GISTs. Immune infiltration was greater in overt GISTs compared with that in lesions with limited malignant potential (miniGISTs), in KIT/PDGFRA-mutated tumors compared with that in KIT/PDGFRA WT tumors, and in PDGFRA-mutated compared with KIT-mutated GISTs. Within the KIT-mutated subset, a higher degree of immune colonization was detected in the intestine. Immune hot tumors showed expression patterns compatible with a potentially proficient but curbed antigen-specific immunity, hinting at sensitivity to immunomodulatory treatments. Poorly infiltrated GISTs, primarily KIT/PDGFRA WT intestinal tumors, showed activation of Hedgehog and WNT/β-catenin immune excluding pathways. This finding discloses a potential therapeutic vulnerability, as the targeting of these pathways might prove effective by both inhibiting pro-oncogenic signals and fostering antitumor immune responses. Finally, an intriguing anticorrelation between immune infiltration and ANO1/DOG1 expression was observed, suggesting an immunomodulatory activity for anoctamin-1.

New therapeutic agents in gastrointestinal stromal tumours

PURPOSE OF REVIEW

The aim of this study was to provide an update on the most recent developments regarding systemic treatments in the various molecular subtypes of gastrointestinal stromal tumour (GIST).

RECENT FINDINGS

Several novel direct inhibitors of KIT and PDGFRA have entered the advanced clinical development in later treatment lines based on promising early clinical trial experience. Both avapritinib and ripretinib are more potent and more specific against various KIT and PDGFRA mutations. For patients with PDGFRA D842V mutations, the next generation of drugs may become the first active treatment options.Comprehensive molecular testing of KIT/PDGFRA-wildtype GIST may unmask clinically relevant targets, including NTRK fusions.

SUMMARY

The treatment landscape in GIST is expected to undergo a profound transformation with more potent drugs currently in late-stage clinical development.