Chemotherapeutics, including the platinum compounds oxaliplatin (OXP) and cisplatin (CDDP), are standard care of treatment for cancer. Although chemotherapy has long been considered immunosuppressive, evidence now suggests that certain cytotoxic agents can efficiently stimulate antitumor responses, through the induction of a form of apoptosis, called immunogenic cell death (ICD). ICD is characterized by exposure of calreticulin and heat shock proteins (HSPs), secretion of ATP and release of high-mobility group box 1 (HMGB1). Proper activation of the immune system relies on the integration of these signals by dendritic cells (DCs). Studies on the crucial role of DCs, in the context of ICD, have been performed using mouse models or human in vitro-generated monocyte-derived DCs (moDCs), which do not fully recapitulate the in vivo situation. Here, we explore the effect of platinum-induced ICD on phenotype and function of human blood circulating DCs. Tumor cells were treated with OXP or CDDP and induction of ICD was investigated. We show that both platinum drugs triggered translocation of calreticulin and HSP70, as well as the release of ATP and HMGB1. Platinum treatment increased phagocytosis of tumor fragments by human blood DCs and enhanced phenotypic maturation of blood myeloid and plasmacytoid DCs. Moreover, upon interaction with platinum-treated tumor cells, CD1c⁺ DCs efficiently stimulated allogeneic proliferation of T lymphocytes. Together, our observations indicate that platinum-treated tumor cells may exert an active stimulatory effect on human blood DCs. In particular, these data suggest that CD1c⁺ DCs are critical mediators of immune responses induced by ICD.

Purpose: In many children with cancer and characteristics suggestive of a genetic predisposition syndrome, the genetic cause is still unknown. We studied the yield of pathogenic mutations by applying whole-exome sequencing on a selected cohort of children with cancer. Experimental Design: To identify mutations in known and novel cancer-predisposing genes, we performed trio-based whole-exome sequencing on germline DNA of 40 selected children and their parents. These children were diagnosed with cancer and had at least one of the following features: (1) intellectual disability and/or congenital anomalies, (2) multiple malignancies, (3) family history of cancer, or (4) an adult type of cancer. We first analyzed the sequence data for germline mutations in 146 known cancer-predisposing genes. If no causative mutation was found, the analysis was extended to the whole exome. Results: Four patients carried causative mutations in a known cancer-predisposing gene: TP53 and DICER1 (n = 3). In another 4 patients, exome sequencing revealed mutations causing syndromes that might have contributed to the malignancy (EP300-based Rubinstein–Taybi syndrome, ARID1A-based Coffin–Siris syndrome, ACTB-based Baraitser–Winter syndrome, and EZH2-based Weaver syndrome). In addition, we identified two genes, KDM3B and TYK2, which are possibly involved in genetic cancer predisposition. Conclusions: In our selected cohort of patients, pathogenic germline mutations causative or likely causative of the cancer phenotype were found in 8 patients, and two possible novel cancer-predisposing genes were identified. Therewith, our study shows the added value of sequencing beyond a cancer gene panel in selected patients, to recognize childhood cancer predisposition. Clin Cancer Res; 24(7); 1594–603. ©2018 AACR.

Classical Hodgkin lymphoma (cHL) represents a B-cell lymphoproliferative disease characterized by clonal immunoglobulin gene rearrangements and recurrent genomic aberrations in the Hodgkin Reed–Sternberg cells in a reactive inflammatory background. Several methods are available for the molecular analysis of cHL on both tissue and cell-free DNA isolated from blood, which can provide detailed information regarding the clonal composition and genetic alterations that drive lymphoma pathogenesis. Clonality testing involving the detection of immunoglobulin and T cell receptor gene rearrangements, together with mutation analysis, represent valuable tools for cHL diagnostics, especially for patients with an atypical histological or clinical presentation reminiscent of a reactive lesion or another lymphoma subtype. In addition, clonality assessment may establish the clonal relationship of composite or subsequent lymphoma presentations within one patient. During the last few decades, more insight has been obtained on the molecular mechanisms that drive cHL development, including recurrently affected signaling pathways (e.g., NF-κB and JAK/STAT) and immune evasion. We provide an overview of the different approaches to characterize the molecular composition of cHL, and the implementation of these next-generation sequencing-based techniques in research and diagnostic settings.

Despite high cure rates in classic Hodgkin lymphoma (cHL), relapses are observed. Whether relapsed cHL represents second primary lymphoma or an underlying T-cell lymphoma (TCL) mimicking cHL is underinvestigated. To analyze the nature of cHL recurrences, in-depth clonality testing of immunoglobulin (Ig) and T-cell receptor (TCR) rearrangements was performed in paired cHL diagnoses and recurrences among 60 patients, supported by targeted mutation analysis of lymphoma-associated genes. Clonal Ig rearrangements were detected by next-generation sequencing (NGS) in 69 of 120 (58%) diagnoses and recurrence samples. The clonal relationship could be established in 34 cases, identifying clonally related relapsed cHL in 24 of 34 patients (71%). Clonally unrelated cHL was observed in 10 of 34 patients (29%) as determined by IG-NGS clonality assessment and confirmed by the identification of predominantly mutually exclusive gene mutations in the paired cHL samples. In recurrences of >2 years, ∼60% of patients with cHL for whom the clonal relationship could be established showed a second primary cHL. Clonal TCR gene rearrangements were identified in 14 of 125 samples (11%), and TCL-associated gene mutations were detected in 7 of 14 samples. Retrospective pathology review with integration of the molecular findings were consistent with an underlying TCL in 5 patients aged >50 years. This study shows that cHL recurrences, especially after 2 years, sometimes represent a new primary cHL or TCL mimicking cHL, as uncovered by NGS-based Ig/TCR clonality testing and gene mutation analysis. Given the significant therapeutic consequences, molecular testing of a presumed relapse in cHL is crucial for subsequent appropriate treatment strategies adapted to the specific lymphoma presentation.

The benign neoplasm cardiac myxoma represents one of the hallmarks of Carney complex (CNC), a familial multiple neoplasia syndrome. About 80% of the index cases have germline mutations in PRKAR1A encoding the RIα regulatory subunit of cAMP-dependent protein kinase A (PKA). However, the role of PRKAR1A gene mutations in the pathogenesis of non-CNC-associated sporadic cardiac myxoma is less well established. Here, we investigated the presence of PRKAR1A gene variants in a cohort of 24 sporadic cardiac myxomas using targeted next-generation sequencing. Our study shows that 14 out of 24 cases (58%) harbor PRKAR1A gene mutations, represented mostly by frameshift, nonsense, and splice site mutations (together 84%), leading to a premature stop codon predicted to be degraded via non-sense mediated mRNA decay. The other 16% of PRKAR1A genetic alterations involved missense mutations, often located in important functional domains of the regulatory subunit RIα. Notably, 64% (n = 9/14) of the cases harbored more than one PRKAR1A gene variant, suggesting compound heterozygous mutations either in cis or trans. In conclusion, PRKAR1A gene mutations associated with loss of RIα function leading to increased PKA activity were observed in ~ 60% of sporadic cardiac myxomas, strongly supporting an essential role for PKA in mediating formation of cardiac myxoma.

Approximately one-third of diffuse large B-cell lymphoma (DLBCL) patients relapse, who often require salvage chemotherapy followed by autologous stem cell transplantation. In most cases, the clonal relationship between the first diagnosis and subsequent relapse is not assessed, thereby missing the identification of second primary lymphoma. Here, the clonal relationship of 59 paired DLBCL diagnosis and recurrences was established by next-generation sequencing (NGS)-based detection of immunoglobulin gene rearrangements. In 50 cases with interpretable results, 43 DLBCL patients (86%) developed clonally related lymphoma and relapsed disease. In total, 100% of early recurrences (< 2 year), 80% of the recurrences with an interval between 2 and 5 years, and 73% of late recurrences (≥ 5 year) were clonally related. In contrast, 7 out of 50 patients (14%) showed distinct dominant clonotypes in primary DLBCL and its recurrences, suggesting the occurrence of second primary DLBCL, which all occurred at least 4 years after primary diagnosis. Moreover, 43% of clonally unrelated cases were Epstein-Barr virus-positive, while this was 3% in relapsed DLBCL. In conclusion, NGS-based clonality testing in late recurrences should be considered in routine diagnostics to distinguish relapse from second primary lymphoma, as this latter group of DLBCL patients may benefit from less intensified treatment strategies.