King, Rebecca L.

Abstract Activated B cell (ABC) type diffuse large B cell lymphoma (DLBCL), double hit lymphoma (DHL) and double expressor lymphoma (DEL) have poor outcomes to frontline R‐CHOP but impact of these molecular features on outcomes of relapsed/refractory (R/R) disease is not well‐characterized. We evaluated the association of diagnostic cell of origin (COO), double hit and double expressor status with overall survival after first relapse in DLBCL patients who were enrolled into the Molecular Epidemiology Resource (MER) cohort. COO was available from immunohistochemistry (IHC) using Hans criteria or gene expression profiling (GEP) (Nanostring) on the diagnostic FFPE biopsy. Of 373 pts with R/R DLBCL, 278 had COO by IHC: 152 were GCB, 107 were non‐GCB. One hundred and fourty had COO by GEP: 44 were ABC, 65 were GCB and 13 were unclassifiable. Nineteen out of 163 (12%) were DHL; 30 out of 135 (22%) had DEL. COO, either by IHC (2 years OS GCB: 45% [CI 95 : 38–54] vs. non‐GCB: 44% [CI 95 :36–55], p > 0.05) or GEP (2 years OS ABC: 42% [CI 95 : 29–59] vs. GCB: 40% [CI 95 : 30–54], p > 0.05), was not associated with difference in OS. DHL (2 years OS 16 [CI 95 :6–45] vs. 45% [CI 95 : 34–59], p < 0.01) and DEL (2 years OS 33% [CI 95 : 20–56], vs. 50% [CI 95 : 41–60], p < 0.05) had lower OS than non‐DHL and non‐DEL/non‐DHL counterparts, respectively. COO by IHC or GEP was not associated with OS in R/R DLBCL while DHL and DEL were adverse prognostic markers in DLBCL at first relapse.

ImportanceRosai-Dorfman disease (RDD) is a rare histiocytic neoplasm with recent studies showing alterations in the MAPK pathway, most commonly in the KRAS and MEK genes in about 40% of patients. Reports on the use of MEK-inhibitor therapy in RDD have been limited to small case studies. There are no approved treatments for this neoplasm, and therefore patients with RDD need efficacious treatments.ObjectiveTo study the outcomes after treatment with cobimetinib based on MAPK pathway alterations in patients with RDD.Design, Setting, and ParticipantsThis retrospective cohort study conducted at 2 tertiary care centers included patients with RDD who underwent treatment with cobimetinib between January 1, 2013, and December 1, 2021. Cobimetinib was administered at a dosage of 20 to 60 mg orally once daily as a single agent for 21 days in a 28-day cycle. Pathology was centrally reviewed. Response assessment was centrally conducted and was based on the established positron emission radiography response criteria used for clinical trials of targeted therapies in histiocytosis.Main Outcomes and MeasuresMain outcomes were overall response rate (ORR), progression-free survival (PFS), adverse events (AEs) of cobimetinib in the entire cohort, and ORRs and PFS based on MAPK pathway alterations in patients with RDD.ResultsA total of 16 patients (median [range] age at cobimetinib initiation, 57 [31-74] years; 11 [69%] women) were included in the study. The median follow-up duration was 19.0 months (95% CI, 8.4-27.8 months). The ORR was 63% (n = 10), including 5 complete responses and 5 partial responses. Somatic alterations in the KRAS or MEK genes were detected in 8 (50%) patients. Patients with KRAS or MEK alterations had significantly higher ORR (88% vs 38%; P = .03), deeper responses (complete responses among responders: 71% vs 0%; P = .002), and better PFS (at 1 year, 100% vs 29% were free from progression or death, respectively; P &amp;lt; .001) compared with those without such alterations. Grade 2 or higher AEs occurred in 12 (75%) patients, and 9 (56%) required dose reduction or temporary/permanent treatment discontinuation due to AEs.Conclusions and RelevanceIn this cohort study, treatment with cobimetinib was associated with positive outcomes in KRAS- or MEK-variant RDD. However, AEs requiring dose modifications were common.

Abstract An enhanced understanding of the molecular heterogeneity of diffuse large B-cell lymphoma (DLBCL) has opened the door to clinical trials evaluating novel agents with subtype-specific activity. It is an emerging question whether core needle biopsies (CNB) can adequately meet the increasing tissue requirements of these clinical trials. This can potentially lead to selective enrollment of patients who can undergo excisional biopsy (EB). It is also important to know whether patients who can undergo extensive diagnostic work up differ in their disease characteristics and outcomes from those who cannot. In this observational study, we describe the characteristics, outcomes, and adequacy of diagnostic tissue in patients with newly diagnosed DLBCL and primary mediastinal large B-cell lymphoma who underwent EB vs CNB. Of the 1061 patients, 532 (49.8%) underwent EB and 529 (50.1%) underwent CNB. A significantly higher proportion of patients with CNB had advanced stage disease, an international prognostic index of ≥3, and inadequate tissue for molecular analyses. Patients with CNB had significantly worse 5-year event-free survival (67.6% vs 56.9%; hazard ratio [HR], 0.76; confidence interval [CI]95, 0.6-0.9, P &lt; .001) and 5-year overall survival (76.4% vs 69.2%; HR, 0.8; CI95, 0.6-0.9, P &lt; .001). Thus, patients who underwent CNB have poor-risk features and inferior outcomes on frontline chemoimmunotherapy, are more likely to have inadequate tissue for molecular analyses, and might not meet the tissue requirements of biomarker-driven clinical trials. Thus, the increasing tissue requirements of biomarker-driven clinical trials may result in the exclusion of patients with high-risk DLBCL who need novel agents.

Abstract Primary leptomeningeal lymphoma is exceedingly rare. We describe 2 rare lymphoma cases with exclusive leptomeningeal disease: 1 ALK-positive (ALK+) anaplastic large cell lymphoma (ALCL) and 1 primary effusion lymphoma (PEL). Case 1: A 19-year-old man presented with symptoms concerning for leptomeningitis. Cerebrospinal fluid (CSF) analysis revealed lymphocytic pleocytosis. Spine MRI demonstrated pial enhancement from T10 through the conus medullaris and cauda equina enhancement/thickening. A biopsy showed leptomeningeal involvement by large lymphoma cells with hallmark cells and brisk mitotic activity. By immunohistochemistry, cells were CD7/CD30-positive with cytoplasmic ALK staining. No systemic disease was identified. The diagnosis of primary leptomeningeal ALK+ ALCL was made. Despite 2 CSF relapses requiring systemic therapy and autologous bone marrow transplant, the patient was in complete clinical remission 9 years after the diagnosis. Case 2: A 60-year-old, human immunodeficiency virus-positive man presented with symptoms suggestive of leptomeningitis. Brain MRIs revealed multifocal, supratentorial, and infratentorial leptomeningeal enhancement. A right frontal biopsy demonstrated leptomeningeal involvement by large lymphoma cells negative for B-cell immunostains, but CD138, MUM-1, and HHV8-positive, with aberrant CD3 expression. EBV-encoded RNA in situ hybridization was positive. In absence of solid lesions/extracranial involvement, the diagnosis of leptomeningeal PEL was rendered. Despite initial complete remission after chemotherapy, the patient died 9 months later.

Abstract With the introduction of large-scale molecular profiling methods and high-throughput sequencing technologies, the genomic features of most lymphoid neoplasms have been characterized at an unprecedented scale. Although the principles for the classification and diagnosis of these disorders, founded on a multidimensional definition of disease entities, have been consolidated over the past 25 years, novel genomic data have markedly enhanced our understanding of lymphomagenesis and enriched the description of disease entities at the molecular level. Yet, the current diagnosis of lymphoid tumors is largely based on morphological assessment and immunophenotyping, with only few entities being defined by genomic criteria. This paper, which accompanies the International Consensus Classification of mature lymphoid neoplasms, will address how established assays and newly developed technologies for molecular testing already complement clinical diagnoses and provide a novel lens on disease classification. More specifically, their contributions to diagnosis refinement, risk stratification, and therapy prediction will be considered for the main categories of lymphoid neoplasms. The potential of whole-genome sequencing, circulating tumor DNA analyses, single-cell analyses, and epigenetic profiling will be discussed because these will likely become important future tools for implementing precision medicine approaches in clinical decision making for patients with lymphoid malignancies.