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Paraneoplastic cerebellar degenerations with anti-Yo antibodies (Yo-PCD) are rare syndromes caused by an auto-immune response against neuronal antigens (Ags) expressed by tumor cells. However, the mechanisms responsible for such immune tolerance breakdown are unknown. We characterized 26 ovarian carcinomas associated with Yo-PCD for their tumor immune contexture and genetic status of the 2 onconeural Yo-Ags, CDR2 and CDR2L. Yo-PCD tumors differed from the 116 control tumors by more abundant T and B cells infiltration occasionally organized in tertiary lymphoid structures harboring CDR2L protein deposits. Immune cells are mainly in the vicinity of apoptotic tumor cells, revealing tumor immune attack. Moreover, contrary to un-selected ovarian carcinomas, 65% of our Yo-PCD tumors presented at least one somatic mutation in Yo-Ags, with a predominance of missense mutations. Recurrent gains of the CDR2L gene with tumor protein overexpression were also present in 59% of Yo-PCD patients. Overall, each Yo-PCD ovarian carcinomas carried at least one genetic alteration of Yo-Ags. These data demonstrate an association between massive infiltration of Yo-PCD tumors by activated immune effector cells and recurrent gains and/or mutations in autoantigen-encoding genes, suggesting that genetic alterations in tumor cells trigger immune tolerance breakdown and initiation of the auto-immune disease.

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Missense mutations in the polymerase epsilon (POLE) gene have been reported to generate proofreading defects resulting in an ultramutated genome and sensitize tumors to checkpoint blockade immunotherapy. However, many POLE mutated tumors do not respond to such treatment. To better understand the link between POLE mutation variants and response to immunotherapy, we. prospectively assessed the efficacy of nivolumab in a multicenter clinical trial in patients bearing advanced mismatch repair proficient POLE-mutated solid tumors. We found that only tumors harboring selective POLE pathogenic mutations in the DNA binding or catalytic site of the exonuclease domain presented high mutational burden with specific single base substitution signature, high T-cell infiltrates, and high response rate to anti-PD1 monotherapy. This study illustrates how specific DNA repair defects can sensitize to immunotherapy, POLE proofreading deficiency representing a novel tumor agnostic biomarker for response to PD-1 checkpoint blockade therapy.

BackgroundRenal cell carcinoma represents 3–5% of adult malignant tumors. Metastases are found in 30–40% of patients and brain metastases occurred in more than 10% of them. Despite significant progress in medical treatment, patients with brain metastases still have a limited survival. Cabozantinib, a tyrosine kinase inhibitor directed against vascular endothelial growth factor receptors, was recently registered for the treatment of metastatic renal cell carcinoma. Almost no data are, however, available on patients with brain metastases.Case presentationCase 1 is a 51-year-old man of North African origin; Case 2 is a 55-year-old European man. Case 1 and Case 2 had metastases of renal carcinoma at initial diagnosis and were treated with vascular endothelial growth factor receptors tyrosine kinase inhibitors. Case 1 had clear cell renal carcinoma and underwent nephrectomy; he then received several lines of tyrosine kinase inhibitor directed against vascular endothelial growth factor receptors and the mTor complex. During the second treatment a brain metastasis was diagnosed and treated with radiosurgery with rapid efficacy. Two years later he received nivolumab, an antibody directed against the programmed death-1 and programmed death-ligand 1 complex, but disease progression was observed with the reappearance of the brain metastasis together with neurologic symptoms. Cabozantinib was administered and induced a rapid clinical improvement as well as tumor regression in all sites including his brain. Sequencing of his tumor evidenced a mutation of the MET gene. Case 2 had a papillary renal carcinoma with brain metastases at time of diagnosis. After radiation of the brain tumors, a vascular endothelial growth factor receptor tyrosine kinase inhibitor was administered for 3 years. The disease was under control in all sites except in his brain; several new brain metastases requiring new radiation treatments developed. The disease finally progressed at all metastatic sites including his brain and he had several neurological symptoms. Cabozantinib was administered and rapidly induced a clinical improvement; a further computed tomography scan and brain magnetic resonance imaging showed significant tumor regressions. No MET gene mutation or amplification was observed in the tumor analysis.ConclusionsThese case reports indicate that cabozantinib was able, first, to reach brain tumors and second, to induce significant regressions in renal carcinoma brain metastases that were resistant to radiation as well as to previous systemic vascular endothelial growth factor receptor tyrosine kinase inhibitors.

PIK3CA mutation was associated with a lower risk of local relapse in this population of BCs. This is consistent with recent studies suggesting PIK3CA to be part of biological pathways impacting the radiosensitivity.

Sebaceous neoplasms are a major clinical feature of Muir-Torre syndrome (MTS) associated with visceral malignancies, especially colorectal and endometrial tumors. The diagnosis of MTS relies largely on the microsatellite instability (MSI) phenotype in tumors, suggesting germline mutations in DNA mismatch repair (MMR) genes responsible for the inherited disease. We hypothesized that in some MSI-H sebaceous tumors, acquired rather than inherited mutations in MMR genes could be involved. Using next-generation sequencing, we screened MMR gene mutations in 18 MSI-H sebaceous tumors. We found mutations in 17 samples (94%). Indeed, 12/17 (71%) were shown to carry acquired somatic mutations and among 12 samples, seven were shown to be associated with additional somatic alterations like loss of heterozygosity or multiple mutations, suggesting somatic second hits. Our findings strongly suggest that somatic MMR deficiency is responsible for a proportion of MSI-H sebaceous tumors.