Pancreatic ductal adenocarcinoma (PDAC) remains a highly lethal malignancy because of its aggressive nature and the paucity of effective treatment options. Almost all registered drugs have proven ineffective in addressing the needs of patients with PDAC. This is the result of a poor understanding of the unique tumor–immune microenvironment (TME) in PDAC. To identify druggable regulators of immunosuppressive TME, we performed a kinome- and membranome-focused CRISPR screening using orthotopic PDAC models. Our data showed that receptor-interacting protein kinase 2 (RIPK2) is a crucial driver of immune evasion of cytotoxic T-cell killing and that genetic or pharmacologic targeting of RIPK2 sensitizes PDAC to anti–programmed cell death protein 1 (anti–PD-1) immunotherapy, leading to prolonged survival or complete regression. Mechanistic studies revealed that tumor-intrinsic RIPK2 ablation disrupts desmoplastic TME and restores MHC class I (MHC-I) surface levels through eliminating NBR1-mediated autophagy-lysosomal degradation. Our results provide a rationale for a novel combination therapy consisting of RIPK2 inhibition and anti–PD-1 immunotherapy for PDAC. Significance: PDAC is resistant to almost all available therapies, including immune checkpoint blockade. Through in vivo CRISPR screen, we identified that RIPK2 plays a crucial role in facilitating immune evasion by impeding antigen presentation and cytotoxic T-cell killing. Targeting tumor-intrinsic RIPK2 either genetically or pharmacologically improves PDAC to anti–PD-1 immunotherapy. See related commentary by Liu et al., p. 208 . This article is featured in Selected Articles from This Issue, p. 201

Background: Germline mutations in the APC gene located on chromosome 5q 21–22 can lead to familial adenomatous polyposis (FAP) and the development of colorectal cancer (CRC) if left untreated. As a rare extracolonic manifestation, thyroid cancer is diagnosed in about 2.6% of FAP patients. The genotype–phenotype correlation in FAP patients with thyroid cancer remains unclear. Case presentation: We present a 20-year-old female of FAP with thyroid cancer as the initial manifestation. The patient was asymptomatic and developed colon cancer liver metastases 2 years after the diagnosis of thyroid cancer. The patient underwent multiple surgical treatments in several organs, and regular colonoscopy with endoscopic polypectomy was performed. Genetic testing demonstrated the c.2929delG (p.Gly977Valfs*3) variant in exon 15 of the APC gene. This represents a previously undescribed APC mutation. This mutation causes loss of multiple structures on the APC gene including the 20-amino acid repeats, the EB1 binding domain, and the HDLG binding site, which may be pathogenic through β-catenin accumulation, cell cycle microtubule dysregulation, and tumor suppressor inactivation. Conclusions: We report a de novo FAP case with thyroid cancer presenting atypically aggressive features harboring a novel APC mutation and review APC germline mutations in patients with FAP-associated thyroid cancer.

Purpose: This study aimed to analyze clinicopathological, survival, prognostic factors, as well as the timing of brain metastases (BM) in colorectal cancer (CRC) using data from a Chinese center. Patients and Methods: Data of 65 consecutive CRC patients with BM were collected from a single institution in China. The time from primary tumor surgery to the occurrence of BM was calculated. Kaplan-Meier analysis was used to evaluate cumulative survival of patients. Factors associated with prognosis of overall survival (OS) were explored using Cox’s proportional hazard regression models. Results: The median time interval from CRC surgery to the diagnosis of BM was 24 months. After diagnosis of BM, median OS values for patients were 11 months. Extracranial metastases occurred in 45 cases (69.2%) when BM was diagnosed, and 58.5% of these patients with lung metastases Time of BMs (P=0.018), presence of extracranial metastases (P=0.033), treatment (P=0.003), CA199 (P=0.034), CA125 (P< 0.001), CA242 (P=0.018), and CA211 (P=0.012) were associated with OS of patients through univariate analysis. Multivariate analysis using a Cox regression model showed that only treatment was an independent predictor for OS (conservative treatment; HR=1.861, 95% CI=1.077– 3.441; P=0.048). Conclusion: Surgical treatment of metastatic lesions may be an alternative choice for CRC patients with BM. Identifying the timing of brain metastases can help to detect this disease early, leading to a better survival outcome.