The proper categorization of mature T-cell neoplasms with coexpression of CD30/CD15 is unresolved. Prior studies suggested an overlap with ALK-negative anaplastic large cell lymphoma (ALCL). We evaluated the morphologic, immunophenotypic, and molecular features of 28 T-cell lymphomas coexpressing CD30/CD15, and performed a comparison with 8 ALK/CD15-negative ALCL and published data. Clinical information was retrieved from the submitting physician. Immunohistochemistry, TRG and IG gene rearrangement, DNA and RNA targeted next-generation sequencing, and fluorescence in situ hybridization for DUSP22 rearrangement were performed. Cases were classified as conforming to 3 histologic variants: ALCL-like, Hodgkin-like, and PTCL-NOS-like. Median age was 62 years (range: 33 to 87). Male:female ratio was 3:1. Twenty-four cases presented with lymphadenopathy (24/28, 85.7%). Six cases had skin involvement (6/28, 21.4%), including 4 primary cutaneous cases (4/28, 14.3%). Ten cases were designated as ALCL-like, 12 as Hodgkin-like, and 2 as PTCL-NOS-like. There was frequent loss of T-cell markers, with expression of CD3 in 7/27 cases (25.9%), CD2 in 15/23 (65.2%), and expression of at least one cytotoxic marker in 13/24 (54.2%). DUSP22 was rearranged in 4 cases (4/16, 25%). The JAK-STAT pathway was frequently altered due to mutations in JAK1 (6/28, 21.4%), STAT3 (5/28, 17.8%), and JAK2 fusions (2/28, 7.1%). PI3K-AKT-mTOR pathway alterations due to PIK3R1 mutations (5/28, 17.8%) were also frequent and mutually exclusive with JAK-STAT pathway activation. In summary, most T-cell neoplasms with CD30/CD15 coexpression share clinical, morphologic, immunophenotypic, and molecular features with ALK -negative ALCL but do not segregate as a homogeneous entity as defined by histologic or genetic features.

Large congenital melanocytic nevi/nevus (LCMN) are caused by genetic events that activate the mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) pathway. Individuals with LCMN are prone to developing aggressive melanomas during childhood. Targeted therapies are needed to treat this form of melanoma and manage LCMN symptoms such as pruritus and pain, which significantly impact quality of life. Here, we present the first case of an LCMN with an NTRK fusion driver event. The patient presented with an atypical proliferative nodule arising in the background nevus. RNA sequencing of the proliferative nodule with background nevus identified a pathogenic LMNA::NTRK1 fusion. The fusion resulted in constitutive expression of TrkA, demonstrated by strong cytoplasmic pan-TRK staining, along with activation of the MAPK/ERK pathway, as indicated by positive nuclear and cytoplasmic staining for phosphorylated ERK. The background nevus beneath the proliferative nodule also expressed pan-TRK and phosphorylated ERK, suggesting that the NTRK1 fusion occurred prior to the formation of the proliferative nodule. This case broadens the spectrum of driver events for LCMN and suggests that screening for TRK fusions in LCMN should be considered when systemic therapy is being considered for melanoma or symptom management.

Limited information is available on the clinicopathologic features and management of pediatric CRTC1::TRIM11 (CTRTs) and MED15::ATF1 -rearranged tumors (MARTs). In this series of pediatric CTRTs ( n  = 5) and MARTs ( n  = 2), all tumors exhibited spitzoid morphology and expressed melanocytic markers. Metastatic progression occurred in one CTRT and two MARTs: all three received immunotherapy, resulting in disease control in two patients and one death due to progressive disease. A fourth individual had lymph node micrometastasis that remained stable without progression. This case series highlights the potentially aggressive behavior of these tumors and suggests that immunotherapy may be an effective treatment option for advanced disease.

The proper categorization of mature T-cell neoplasms with coexpression of CD30/CD15 is unresolved. Prior studies suggested an overlap with ALK-negative anaplastic large cell lymphoma (ALCL). We evaluated the morphologic, immunophenotypic, and molecular features of 28 T-cell lymphomas coexpressing CD30/CD15, and performed a comparison with 8 ALK/CD15-negative ALCL and published data. Clinical information was retrieved from the submitting physician. Immunohistochemistry, TRG and IG gene rearrangement, DNA and RNA targeted next-generation sequencing, and fluorescence in situ hybridization for DUSP22 rearrangement were performed. Cases were classified as conforming to 3 histologic variants: ALCL-like, Hodgkin-like, and PTCL-NOS-like. Median age was 62 years (range: 33 to 87). Male:female ratio was 3:1. Twenty-four cases presented with lymphadenopathy (24/28, 85.7%). Six cases had skin involvement (6/28, 21.4%), including 4 primary cutaneous cases (4/28, 14.3%). Ten cases were designated as ALCL-like, 12 as Hodgkin-like, and 2 as PTCL-NOS-like. There was frequent loss of T-cell markers, with expression of CD3 in 7/27 cases (25.9%), CD2 in 15/23 (65.2%), and expression of at least one cytotoxic marker in 13/24 (54.2%). DUSP22 was rearranged in 4 cases (4/16, 25%). The JAK-STAT pathway was frequently altered due to mutations in JAK1 (6/28, 21.4%), STAT3 (5/28, 17.8%), and JAK2 fusions (2/28, 7.1%). PI3K-AKT-mTOR pathway alterations due to PIK3R1 mutations (5/28, 17.8%) were also frequent and mutually exclusive with JAK-STAT pathway activation. In summary, most T-cell neoplasms with CD30/CD15 coexpression share clinical, morphologic, immunophenotypic, and molecular features with ALK-negative ALCL but do not segregate as a homogeneous entity as defined by histologic or genetic features.

Ewing sarcoma (ES) is a pediatric malignancy that lacks adequate therapies for its metastatic form. These tumors constitutively express neuropeptide Y (NPY) and its Y5 receptor (Y5R), which leads to elevated levels of the peptide in patients' serum. In animal models, xenografts secreting NPY metastasize to extrapulmonary niches, including bone; the phenotype associated with adverse prognosis in ES patients. To determine the role of the NPY/Y5R axis in ES extrapulmonary dissemination, we used a doxycycline-inducible CRISPR/Cas9 system to knockout Y5R in SK-ES-1 xenografts that metastasize to these niches. We have shown that metastases developing from heterogenous SK-ES-1/Y5R-sgRNA primary tumors in doxycycline-treated mice were initiated exclusively by SK-ES-1 clones with a functional NPY5R gene. Similarly, metastasis from wild type SK-ES-1 xenografts was associated with a selection of clones with NPY5R gene gain. In vitro assays identified Y5R-dependent ES cell motility driven by RhoA activation as the mechanism underlying the metastatic effects of NPY. In ES cell lines that secrete NPY, the autocrine NPY/Y5R loop was responsible for maintaining basal cell motility, while ES cells that do not release the peptide responded to the exogenous NPY. These data provide evidence for the crucial role of the NPY/Y5R axis in ES metastasis.

Objective We describe a large family of patients with canonical Von Hippel-Lindau (VHL) manifestations, including central nervous system and retinal hemangioblastomas, clear cell renal cell carcinoma (ccRCC), pancreatic neuroendocrine tumors, and pheochromocytomas, all who lacked any detectable alteration within the VHL gene. Analysis of a ccRCC demonstrated a novel p.E92G variant in the Elongin C gene, ELOC, a known ccRCC tumor suppressor gene. We aim to confirm that the ELOC variant is responsible for the VHL manifestations in this family. Methods Germline testing and tumor analysis were performed to assess the molecular alterations in the lesions in this family. Abdominal imaging was used to determine the sizes of VHL-related lesions. Results We demonstrated this ELOC p.E92G variant was a germline alteration and was present in each affected individual that received genetic testing, demonstrating co-segregation of variant and disease. Analysis of tumors excised from 2 patients demonstrated loss of heterozygosity for the ELOC variant and single copy chromosomal loss of chromosome 8 that encodes the ELOC gene, consistent with inactivation of a tumor suppressor gene. Two patients who received Belzutifan showed a decrease in size of their kidney, pancreatic, and spinal lesions and 1 showed improvement of retinal manifestations. Conclusion These findings indicate that the p.E92G ELOC variant is responsible for the VHL manifestations in this family, and that these tumors are being driven by loss of the VCB-Cul2 E3-ubiquitin ligase complex activity

MET pathway activation is one of the most common mechanisms of resistance to osimertinib in EGFR-mutant non-small cell lung cancer (NSCLC). We previously demonstrated spatial and temporal heterogeneity in MET pathway activation upon osimertinib resistance in EGFR-mutant NSCLC; however, the functional relevance of these findings is unclear. Here, we generated 19 patient-derived xenografts (PDX) from 9 patients with multi-region and temporal sampling of osimertinib-resistant tumor tissue from patients with EGFR-mutant NSCLC. MET pathway activation was a putative mechanism of osimertinib resistance in 66% (n = 6/9) patients from whom PDXs were generated. Significant spatial and temporal heterogeneity in MET pathway activation was evident. Osimertinib-resistant PDXs with MET amplification by FISH (defined as MET/CEP7 ratio >= 2.0 or mean MET >= 6.0 copies/cell) and high-level phospho-MET, but not c-MET expression, had better responses to osimertinib and savolitinib combination than to osimertinib alone. MET polysomy tumors by FISH from both PDXs and patients had evidence of subclonal phospho-MET expression. Select MET polysomy PDX tumors with phospho-MET expression responded better to osimertinib and savolitinib combination than MET polysomy PDX tumors without phospho-MET expression. Our results suggest osimertinib and savolitinib combination is most effective for osimertinib-resistant EGFR-mutant tumors with MET pathway activation as evidenced by phospho-MET. As subclonal MET amplification may be evident in MET polysomy tumor progression, MET polysomy warrants close clinical follow-up with phospho-MET IHC in parallel with FISH diagnostic.Significance: Using a novel cohort of in vivo PDX models of MET pathway activation with acquired resistance to osimertinib in EGFR-mutant lung cancer, we demonstrate that phospho-MET may be a clinically relevant assay to guide treatment selection with osimertinib and savolitinib combination. In addition, our work shows that patients with MET polysomy tumors may have subclonal MET amplification and therefore require close follow up for the use of osimertinib and savolitinib combination.

von Hippel-Lindau (VHL) is an autosomal-dominant hereditary tumour susceptibility disease associated with pathogenic germline variants in the VHL tumour suppressor gene. VHL patients are at increased risk of developing multiple benign and malignant tumours. Current CLIA-based genetic tests demonstrate a very high detection rate of germline VHL variants in patients with clinical manifestations of VHL. In this report, we describe a large family with canonical VHL manifestations, for which no germline alteration had been detected by conventional germline testing. We identified a novel 291 kb chromosomal inversion involving chromosome 3p in affected family members. This inversion disrupts the VHL gene between exon 2 and exon 3 and is thereby responsible for the disease observed in this family.

Abstract Background: Relapsed/refractory (R/R) aggressive lymphomas, including diffuse large B-cell lymphoma (DLBCL), high-grade B-cell lymphoma double-hit (HGBCL-DH), and peripheral T-cell lymphoma (PTCL), have poor outcomes with standard therapy. VIP152 (enitociclib) leads to rapid depletion of short-lived mRNA transcripts such as MYC and MCL1 through CDK9 inhibition. Preclinical studies have identified BCL2 overexpression as a mechanism of resistance to CDK9 inhibition, and synergistic cytotoxicity has been shown with venetoclax (BCL2 inhibitor), steroids, and CDK9 inhibitors in DLBCL. Based on this preclinical data, we hypothesized that the combination of VIP152 with venetoclax and prednisone (VVIP) would result in acceptable safety and improved efficacy in R/R lymphoid malignancies. Methods: R/R non-GCB DLBCL, MYC-rearranged DLBCL/HGBCL-DH, and PTCL pts after 2 prior systemic therapies are eligible. In phase I, pts are treated at 4 dose levels (DL) of VIP152 and venetoclax in combination with fixed-dose prednisone to identify the recommended phase II dose (RP2D). VIP152 (15mg, 22.5mg, or 30mg) is given IV on days 2 and 9 in combination with venetoclax (600mg or 800mg) PO and prednisone 100 mg PO on days 1-10 every 21 days. Phase II expansion cohorts are included at the RP2D. VVIP x 12 cycles is given for pts who achieve complete response (CR), with a max of 24 cycles for pts not in CR. TLS, G-CSF, and PCP prophylaxis are given to all pts. Baseline CT, PET, and BM are performed with CT after cycles 1 and 2 then every 2 cycles and PET after cycles 6 and 12. CT is then performed q3m x 1y, q4m x 1y, q6m x 1y, then q12m x 2y post-therapy. Results: As of March 26, 2024, 5 pts were enrolled (3 at DL1 and 2 at DL2), including 3 PTCL, 1 non-GCB DLBCL, and 1 HGBCL-DH. Median (range) age was 56 (55-77) yrs, with stage 3/4 disease in 100%, >/=2 extranodal sites in 100%, IPI >/=3 in 80%, and elevated LDH in 40%. Median (range) prior therapies were 3 (3-6), with prior ASCT, allo-HSCT, and CAR-T in 1 (20%) pt each, and 80% of pts refractory per SCHOLAR-1 criteria. All 5 pts completed the dose-limiting toxicity (DLT) window with no DLTs observed. The most common adverse events (AEs) (% pts) included hypokalemia (100%), thrombocytopenia (80%), neutropenia (80%), and anemia (80%). Two (40%) pts had G3-4 neutropenia and 1 (20%) pt had G3 hypokalemia, with no other >/=G3 AEs observed. No dose reductions occurred and only 1 pt required a dose delay due to infection. Tumor reduction was observed in 80% (4/5) of pts, with an overall response rate of 60% (3/5). Partial responses include 1 HGBCL-DH pt refractory to both CAR-T and epcoritamab (71% tumor reduction) and 2 PTCL pts refractory to CHOP and targeted therapy (86% and 91% tumor reduction). Four pts have progressed, and no pts have died. Conclusions: Preliminary results show VVIP to be safe and well tolerated with no DLTs observed. Early activity is noted in pts with HGBCL-DH and PTCL. Enrollment continues to identify the RP2D and to further assess the safety and efficacy of VVIP in R/R aggressive lymphomas. Citation Format: Christopher Melani, Max Gordon, Rahul Lakhotia, Stefania Pittaluga, Jillian Simard, Jagan Muppidi, James D. Phelan, Svetlana Pack, Amynah Pradhan, Candis Morrison, Atekelt Tadese, Anna M. Juanitez, Amy J. Johnson, Melanie M. Frigault, Ahmed Hamdy, Mark Roschewski, Louis M. Staudt, Wyndham H. Wilson. Phase I/II study of VIP152 (enitociclib), venetoclax, and prednisone (VVIP) in relapsed/refractory (R/R) lymphoid malignancies [abstract]. In: Proceedings of the Fourth AACR International Meeting on Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2024 Jun 19-22; Philadelphia, PA. Philadelphia (PA): AACR; Blood Cancer Discov 2024;5(3_Suppl):Abstract nr PO-008.

Peripheral T-cell lymphomas (PTCL) are morphologically and biologically heterogeneous and a subset expresses CD30, including anaplastic large cell lymphomas (ALCL) and a minority of PTCL, not otherwise specified (PTCL, NOS). ALCL with ALK translocations (ALCL, ALK+) are readily identified by routine diagnostic methods, but differentiating ALCL without ALK translocation (ALCL, ALK-) and PTCL, NOS expressing CD30 (PTCL CD30+) can be challenging. Furthermore, rare PTCL co-express CD30 and CD15 (PTCL CD30+CD15+); some resemble ALCL, ALK- while others resemble classic Hodgkin lymphoma. To explore the relationship between PTCL CD30+CD15+ and ALCL, ALK-, we analysed 19 cases of PTCL with CD30 expression, previously diagnosed as ALCL, ALK- (nine cases) and PTCL CD30+CD15+ (10 cases) for DUSP22/IRF4 rearrangements, coding RNA expression and selected transcriptome analysis using the NanoString nCounter gene expression analysis platform. Unsupervised clustering showed no clear segregation between ALCL, ALK- and PTCL CD30+CD15+. Three cases previously classified as PTCL CD30+CD15+ showed DUSP22/IRF4 rearrangements, favouring a diagnosis of ALCL, ALK-. Our results suggest that cases previously designated PTCL CD30+CD15+, likely fall within the spectrum of ALCL, ALK-; additionally, a subset of ALCL, ALK- with DUSP22/IRF4 rearrangement expresses CD15, consistent with previous reports and expands the immunophenotypic spectrum of this lymphoma subgroup.

Tumor/Normal paired whole exome sequencing (T/N-WES) testing permits the identification of actionable somatic variants for therapeutic decision-making, in addition to clinically significant germline variants. The identification of germline pathogenic/likely pathogenic (P/LP) variants associated with heritable conditions enables the development of a systematic management plan for the patient as well as cascade testing of at-risk relatives. However, limited resources in molecular labs specialized in the detection of somatic variants, including clinical data and personnel trained in clinical genetics, can impede germline variant curation and implementation of a comprehensive care plan.

Indeterminate dendritic cell histiocytosis (IDCH) is a rare and poorly understood entity characterized by accumulation of CD1a(+)/S100(+) histiocytes (as Langerhans cell histiocytosis [LCH]) but with reduced-absent expression of Langerin/CD207. We assembled 43 cases of IDCH (defined by CD1a(+)/CD207(<20%) immunophenotypic profile) examining the clinical, pathologic, and molecular landscape. Median age at presentation was 70 years (interquartile range, 44-80) with cutaneous (31/43; 72%) and nodal (11/43; 26%) involvement predominating. Eighteen (42%) individuals had an associated nonhistiocytic hematopoietic neoplasm ("secondary" IDCH) whereas 7 of 43 (16%) had a concurrent non-IDCH histiocytosis ("mixed" histiocytosis). Most cases exhibited morphology indistinguishable from LCH but with a CD1c(+)/CSF1R(CD115)(-) phenotype, mirroring the signature of normal indeterminate cells and conventional DC type 2. Mutational analysis revealed frequent KRAS (13/32; 41%) and BRAF p.V600E (11/36, 31%) mutations that were nearly mutually exclusive. RNA-sequencing analysis uncovered ETV3::NCOA2 fusion in 6 other patients presenting as a sole genetic alteration without any other concurrent histiocytic or hematopoietic neoplasm. BRAF and MAP2K1 alterations were significantly associated with partial/retained (1%-20%) Langerin expression (P = .005) and mixed histiocytosis (P = .002). Remarkably, myeloid alterations (DNMT3A, TET2, and SRSF2) co-occurred in IDCH tissues of several individuals. Paired sequencing of IDCH and concurrent non-IDCH hematopoietic neoplasm in 4 individuals revealed shared mutations. Age at diagnosis and any nodal involvement at diagnosis predicted inferior overall survival, but BRAF/RAS pathway alterations did not affect outcome. These data have implications for the diagnostic evaluation, classification, and therapeutic management of IDCH.

Supplemental Figure 3. Further evaluation of CDK4/6 inhibitor sensitivity in fusion-positive and fusion-negative RMS cells.

Primary cutaneous follicle center lymphoma has been distinguished from nodal follicular lymphoma (FL) based on genomic and clinical features. The nature of other extranodal FLs is not well defined. We report 15 cases of follicle center lymphoma involving the lower female genital tract. Cases were evaluated using an immunohistochemical panel for B-cell lymphoma, B-cell clonality, fluorescence in situ hybridization for BCL2 gene rearrangement, and next-generation sequencing. All patients had localized disease with no evidence of bone marrow involvement. Most cases (12/15, 80%) had a follicular pattern, at least focally. Large centrocytes were a prominent feature leading to concern for diffuse large B-cell lymphoma by referring pathologists. Neoplastic cells were positive for CD20 and BCL-6, while BCL-2 was positive in 2/15 (13%) cases. Fluorescence in situ hybridization for BCL2 gene rearrangement was negative in 10/11 (91%) cases. Next-generation sequencing performed in 10 cases revealed TNFRSF14 as the most frequently mutated gene in 6/10 (60%) cases. No case had CREBBP or KMT2D mutations as seen in nodal FL. None of the patients had progressive disease with durable complete remission achieved in 10/12 (83%) cases. The median follow-up period was 7.8 years (range: 0.2 to 20.5 y) with a 5-year overall survival of 100%. We conclude that follicle center lymphoma of the lower female genital tract is a novel variant of primary cutaneous follicle center lymphoma. Despite a frequent component of large cells, it is characterized by localized disease and low risk for dissemination. Awareness and recognition are important to distinguish these lesions from aggressive B-cell lymphomas.

Supplemental Figure 2. Depletion of CDK4 represses the proliferative and transformative capacity of non-amplified fusion-positive RMS cells.

Supplementary Figures 1 and 3 from Conditional Expression of the CTCF-Paralogous Transcriptional Factor BORIS in Normal Cells Results in Demethylation and Derepression of MAGE-A1 and Reactivation of Other Cancer-Testis Genes

Supplementary Figure 2 from Conditional Expression of the CTCF-Paralogous Transcriptional Factor BORIS in Normal Cells Results in Demethylation and Derepression of MAGE-A1 and Reactivation of Other Cancer-Testis Genes