A subset (7–10%) of gastric GISTs is notable for the immunohistochemical loss of succinate dehydrogenase (SDH) subunit B (SDHB), which signals the loss of function of the SDH-complex consisting of mitochondrial inner membrane proteins. These SDH-deficient GISTs are known to be KIT/PDGFRA wild type, and most patients are young. Some of these patients have germline mutations of SDH-subunits B, C, or D, known as Carney-Stratakis syndrome when combined with paraganglioma. More recently, germline mutations in SDH-subunit A (SDHA) have been also reported in few patients with KIT/PDGFRA wild type GISTs. In this study we examined immunohistochemically 127 SDHB-negative and 556 SDHB-positive gastric GISTs and 261 SDHB-positive intestinal GISTs for SDHA expression using a mouse monoclonal antibody 2E3 (Abcam). Cases with available DNA were tested for SDHA, B, C, and D gene mutations using a hybridization-based custom capture next-generation sequencing assay. A total of 36 SDHA-negative GISTs (28%) were found among 127 SDHB-negative gastric GISTs. No SDHB-positive GIST was SDHA-negative. Among 7 SDHA-negative tumors analyzed, there were 7 SDHA mutants, most germline. A second hit indicating biallelic inactivation of SDHA was present in 6 of those cases. These patients had no other SDH subunit mutations. Among the 25 SDHA-positive, SDHB-negative GISTs analyzed, we identified 3 SDHA mutations (one germline), and 11 SDHB, SDHC or SDHD mutations (mostly germline), and 11 patients with no SDH mutations. Compared with patients with SDHA-positive GISTs, those with SDHA-negative GISTs had an older median age (34 vs. 21 years), lower female to male ratio (1.8 vs. 3.1) but similar mitotic counts and median tumor sizes, with a slow course of disease in most cases, despite a slightly higher rate of liver metastases. SDHA-negative GISTs comprise approximately 30% of SDHB-negative/SDH-deficient GISTs, and SDHA loss generally correlates with SDHA mutations.

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The phase II CAVALLI (NCT02055820) study assessed efficacy and safety of venetoclax, a selective, B-cell lymphoma-2 (Bcl-2) inhibitor, with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in first-line (1L) diffuse large B-cell lymphoma (DLBCL), including patients demonstrating Bcl-2 protein overexpression by immunohistochemistry (Bcl-2 IHC-positive). Eligible patients ≥18 years with previously untreated DLBCL, Eastern Cooperative Oncology Group performance status ≤2, and International Prognostic Index 2-5. Venetoclax 800 mg (days 4-10, cycle 1 and days 1-10, cycles 2-8) was administered with rituximab (8 cycles) and CHOP (6-8 cycles); 21-day cycles. Primary endpoints: safety, tolerability, and complete response (CR) at end of treatment (EOT). Secondary endpoints: progression-free survival (PFS) and overall survival. Comparative analyses used covariate-adjusted R-CHOP controls from the GOYA/BO21005 study, an appropriate contemporary benchmark for safety and efficacy. Safety and efficacy analyses included 206 patients. CR rate at EOT was 69% in the overall population and was maintained across Bcl-2 IHC-positive subgroups. With median follow-up of 32.2 months, trends were observed for improved investigator-assessed PFS for venetoclax plus R-CHOP in the overall population (Hazard ratio [HR] = 0.61, 95% confidence interval [CI], 0.43-0.87) and Bcl-2 IHC-positive subgroups (HR = 0.55, 95% CI, 0.34-0.89), versus R-CHOP. Despite a higher incidence of grade 3/4 hematologic adverse events (86%), related mortality was not increased (2%). Chemotherapy dose intensity was similar in CAVALLI versus GOYA. The addition of venetoclax to R-CHOP in 1L DLBCL demonstrates increased but manageable myelosuppression and the potential of improved efficacy particularly in high-risk, Bcl-2 IHC-positive patient subgroups.

Genentech would like to thank the patients, their families and caregivers, as well as the M12-175 study investigators, research, and supporting staff.Medical writing support was provided by Dalia Majumdar, PhD, of AbbVie. Data Sharing StatementAbbVie is committed to responsible data sharing regarding the clinical trials we sponsor. This includes access to anonymized, individual, and trial-level data (analysis data sets), as well as other information (e.g., protocols and Clinical Study Reports), as long as the trials are not part of an ongoing or planned regulatory submission. This includes requests for clinical trial data for unlicensed products and indications.This clinical trial data can be requested by any qualified researchers who engage in rigorous, independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan (SAP) and execution of a Data Sharing Agreement (DSA). Data requests can be submitted at any time and the data will be accessible for 12 months, with possible extensions considered. For more information on the process, or to submit a request, visit the following link: https://www.abbvie.com/our-science/clinical-trials/clinical-trials-data-andinformation-sharing/data-and-information-sharing-with-qualified-researchers.html