Ferroptosis in Intrahepatic Cholangiocarcinoma: IDH1105GGT Single Nucleotide Polymorphism Is Associated With Its Activation and Better Prognosis.

Objectives: Intrahepatic cholangiocarcinoma (ICC) has a dismal prognosis and often demonstrates an anti-apoptotic landscape, which is a key step to chemotherapy resistance. Isocitrate dehydrogenase 1 or 2 (IDH1-2)-mutated ICCs have been described and associated with better prognosis. Ferroptosis is a regulated iron-mediated cell death induced by glutathione peroxidase 4 (GPX4) inhibition, and may be triggered pharmacologically. GPX4 is overexpressed in aggressive cancers, while its expression is inhibited by IDH1 R132C mutation in cell lines. We investigated tissue expression of ferroptosis activation markers in ICC and its correlation with clinical-pathological features and IDH1-2 status. Materials and Methods: We enrolled 112 patients who underwent hepatic resection or diagnostic liver biopsy for ICC. Immunostaining for transferrin-receptor 1 and GPX4, and Pearls' stain for iron deposits were performed to evaluate ferroptosis activation. Immunostaining for STAT3 was performed to study pro-inflammatory and anti-apoptotic landscape. Main IDH1-2 mutations were investigated in 90 cases by real-time polymerase chain reaction. Results: GPX4 overexpression was seen in 79.5% of cases and related to poor histological prognostic factors (grading and perineural and vascular invasion; p < 0.005 for all) and worse prognosis (OS p = 0.03; DFS p = 0.01). STAT3 was expressed in 95.5% of cases, confirming the inflammation-related anti-apoptotic milieu in ICC, and directly related to GPX4 expression (p < 0.0001). A high STAT3 expression correlated to a worse prognosis (OS p = 0.02; DFS p = 0.001). Nearly 12% of cases showed IDH1 105GGT single nucleotide polymorphism, which was never described in ICC up to now, and was related to lower tumor grade (p < 0.0001), longer overall survival (p = 0.04), and lower GPX4 levels (p = 0.001). Conclusion: Our study demonstrates for the first time that in most inflammatory ICCs ferroptosis is not active, and its triggering is related to IDH1-2 status. This supports the possible therapeutic role of ferroptosis-inducer drugs in ICC patients, especially in drug-resistant cases.

Dual-Genotype Diffuse Low-Grade Glioma: Is It Really Time to Abandon Oligoastrocytoma As a Distinct Entity?

We report a unique case of dual-genotype oligoastrocytoma characterized by IDH2 gene mutation. The tumor was resected from the temporal lobe of a 25-year-old man. At histological examination with hematoxylin and eosin stain, it showed distinct oligodendroglial and astrocytic areas. The former retained alpha-thalassaemia/mental retardation X-linked (ATRX) immuno-expression and had absent staining for p53, while the latter had ATRX loss and p53 over-expression. Molecular analyses were separately assessed in the 2 tumor components. Gene sequencing disclosed IDH2 mutation in both, whereas oligodendroglial, but not astrocytic areas, had 1p/19q codeletion and telomerase reverse transcriptase promoter mutation. Distinction of dual-genotype oligoastrocytoma from oligodendroglioma and astrocytoma might be clinically relevant for prognosis and therapy. Because most studies that investigated the molecular phenotype of oligoastrocytomas have focused on IDH1 R132H mutated cases, we suggest further analyses on diffuse gliomas with heterogeneous (astrocytic and oligodendroglial) morphology before oligoastrocytoma is dismissed as a distinct nosological entity.

Concomitant KIT/BRAF and PDGFRA/BRAF mutations are rare events in gastrointestinal stromal tumors.

AIM: The BRAF mutation is a rare pathogenetic alternative to KIT/PDGFRA mutation in GIST and causes Imatinib resistance. A recent description of KIT and BRAF mutations co-occurring in an untreated GIST has challenged the concept of their being mutually exclusive and may account for ab initio resistance to Imatinib, even in the presence of Imatinib-sensitive KIT mutations. BRAF sequencing is generally limited to KIT/PDGFRA wild-type cases. Hence, the frequency of concomitant mutations may be underestimated. METHODS: We screened for KIT (exon 9, 11 ,13 ,17), PDGFRA (exon 12,14, 18) and BRAF (exon 15) mutations a series of 407 GIST. Additionally, we evaluated the BRAF V600E mutation-specific antibody, VE1, as a surrogate for V600E mutation, on a series of 313 GIST (24 on whole sections, 288 cases on tissue array), including 6 cases molecularly ascertained to carry the BRAF V600E mutation. RESULTS: No concomitant KIT/BRAF or PDGFRA/BRAF mutations were detected. BRAF mutation was detected only in one case, wild-type for KIT/PDGFRA. All the 6 BRAF-mutant cases stained positive with the VE1 antibody. A weak VE1 expression was observed in 14/287 (4.9%) BRAF wild-type cases, as observed also in 2/6 BRAF-mutant cases. Overall in our series, sensitivity and specificity of the VE1 antobody were 100% and 95.1%, respectively. CONCLUSIONS: The concomitance of BRAF mutation with either KIT or PDGFRA mutation is rare in GIST. In these tumors, moderate/strong VE1 immunoreactivity is a valuable surrogate for molecular analysis. Instead, genotyping is warranted in the presence of weak VE1 staining.

KIT, PDGFRA, and BRAF mutational spectrum impacts on the natural history of imatinib-naive localized GIST: a population-based study.

The mutation status of KIT or PDGFRA notoriously affects the response of advanced gastrointestinal stromal tumors (GISTs) to tyrosine kinase inhibitors. Conversely, it is currently still unclear whether mutation status impinges on the prognosis of localized, untreated GISTs. Hence, at present, this variable is not included in decision making for adjuvant therapy. A series of 451 primary localized GISTs were analyzed for KIT, PDGFRA, and BRAF mutations. Univariable and multivariable analyses and a backward selection procedure were used to assess the impact of mutation status on overall survival and to identify prognostically homogenous groups. Mutation was a significant prognostic indicator of overall survival in naive, localized GISTs (P<0.001): KIT-mutated patients had a worse outcome than PDGFRA-mutated or triple-negative (KIT, PDGFRA, BRAF wild-type) cases. Multivariable Cox regression models allowed us to identify 3 molecular risk groups: group I exhibited the best outcome and included PDGFRA exon 12, BRAF, and KIT exon 13-mutated cases; group II, of intermediate clinical phenotype (HR=3.06), included triple-negative, KIT exon 17, PDGFRA exon 18 D842V, and PDGFRA exon 14-mutated cases; group III displayed the worst outcome (hazard ratio=4.52), and comprised KIT exon 9 and exon 11 and PDGFRA exon 18 mutations apart from D842V. This study highlights the prognostic impact of mutation status on the natural course of GIST and suggests that the molecular prognostic grouping may complement the conventional clinicopathologic risk stratification criteria in decision making for adjuvant therapy.

Molecular and clinicopathologic characterization of gastrointestinal stromal tumors (GISTs) of small size.

Although Gastrointestinal stromal tumors (GISTs) affect about 0.0014% of the population, GISTs smaller than 1 cm (microGISTs) are detectable in about 20% to 30% of elderly individuals. This suggests that microGISTs likely represent premalignant precursors that evolve only in a minute fraction of cases toward overt GISTs. We sought histopathologic and molecular explanations for the infrequent clinical progression in small GISTs. To investigate the mechanisms of GIST progression and identify subsets with differential malignant potential, we carried out a thorough characterization of 170 GISTs <2 cm and compared their KIT/PDGFRA status with overt GISTs. The proliferation was lower in microGISTs compared with GISTs from 1 to 2 cm (milliGISTs). In addition, microGISTs were more frequently incidental, gastric, spindle, showed an infiltrative growth pattern, a lower degree of cellularity, and abundant sclerosis. The progression was limited to 1 ileal and 1 rectal milliGISTs. KIT/PDGFRA mutations were detected in 74% of the cases. The overall frequency of KIT/PDGFRA mutation and, particularly, the frequency of KIT exon 11 mutations was significantly lower in small GISTs compared with overt GISTs. Five novel mutations, 3 in KIT (p.Phe506Leu, p.Ser692Leu, p.Glu695Lys) 2 in PDGFRA (p.Ser847X, p.Ser667Pro), plus 4 double mutations were identified. Small GISTs share with overt GIST KIT/PDGFRA mutation. Nevertheless, microGISTs display an overall lower frequency of mutations, particularly canonical KIT mutations, and also carry rare and novel mutations. These molecular features, together with the peculiar pathologic characteristics, suggest that the proliferation of these lesions is likely sustained by weakly pathogenic molecular events, supporting the epidemiologic evidence that microGISTs are self-limiting lesions.

Tumors induce a subset of inflammatory monocytes with immunosuppressive activity on CD8+ T cells.

Active suppression of tumor-specific T lymphocytes can limit the efficacy of immune surveillance and immunotherapy. While tumor-recruited CD11b+ myeloid cells are known mediators of tumor-associated immune dysfunction, the true nature of these suppressive cells and the fine biochemical pathways governing their immunosuppressive activity remain elusive. Here we describe a population of circulating CD11b+IL-4 receptor alpha+ (CD11b+IL-4Ralpha+), inflammatory-type monocytes that is elicited by growing tumors and activated by IFN-gamma released from T lymphocytes. CD11b+IL-4Ralpha+ cells produced IL-13 and IFN-gamma and integrated the downstream signals of these cytokines to trigger the molecular pathways suppressing antigen-activated CD8+ T lymphocytes. Analogous immunosuppressive circuits were active in CD11b+ cells present within the tumor microenvironment. These suppressor cells challenge the current idea that tumor-conditioned immunosuppressive monocytes/macrophages are alternatively activated. Moreover, our data show how the inflammatory response elicited by tumors had detrimental effects on the adaptive immune system and suggest novel approaches for the treatment of tumor-induced immune dysfunctions.

Leukocyte infiltration in cancer creates an unfavorable environment for antitumor immune responses: a novel target for therapeutic intervention.

The interaction between tumor cells and the nearby environment is being actively investigated to explore how this interplay affects the initiation and progression of cancer. Host-tumor relationship results in the production of pro-inflammatory cytokines and chemokines that promote the recruitment of leukocytes within and around developing neoplasms. Cancer cells, together with newly recruited tumor-infiltrating cells, can also activate fibroblast and vascular responses, thus resulting in a chronic microenvironment perturbation. In this complex scenario, interactions between innate and adaptive immune cells can be disturbed, leading to a failure of immune-mediated tumor recognition and destruction. On the basis of the recent awareness about tumor promotion and immune deregulation by immune/inflammatory cells, novel anti-cancer strategies can be exploited.

Derangement of immune responses by myeloid suppressor cells.

In tumor-bearing mice and cancer patients, tumor progression is often associated with altered hematopoiesis leading to the accumulation of myeloid cells. Extensive studies in preclinical models indicate that these cells share the CD11b and the Gr-1 markers, possess a mixed mature-immature myeloid phenotype, and are responsible for the induction of T-cell dysfunctions, both tumor-specific and nonspecific. Moreover, CD11b(+)Gr-1(+) myeloid cells are described under different unrelated situations associated with temporary impairment of the T-lymphocyte reactivity. This review examines recent findings on the nature, properties, and mechanisms of action of these myeloid suppressor cells (MSCs).