RESUMEN
Diffuse large B-cell lymphoma (DLBCL) is a commonly diagnosed, aggressive non-Hodgkin's lymphoma. While R-CHOP chemoimmunotherapy is potentially curative, about 40% of DLBCL patients will fail, highlighting the need to identify biomarkers to optimize management. SAMHD1 has a dNTPase-independent role in promoting resection to facilitate DNA double-strand break (DSB) repair by homologous recombination. We evaluated the relationship of SAMHD1 levels with sensitivity to DSB-sensitizing agents in DLBCL cells and the association of SAMHD1 expression with clinical outcomes in 79 DLBCL patients treated with definitive therapy and an independent cohort dataset of 234 DLBCL patients. Low SAMHD1 expression, Vpx-mediated, or siRNA-mediated degradation/depletion in DLBCL cells was associated with greater sensitivity to doxorubicin and PARP inhibitors. On Kaplan-Meier log-rank survival analysis, low SAMHD1 expression was associated with improved overall survival (OS), which on subset analysis remained significant only in patients with advanced stage (III-IV) and moderate to high risk (2-5 International Prognostic Index (IPI)). The association of low SAMHD1 expression with improved OS remained significant on multivariate analysis independent of other adverse factors, including IPI, and was validated in an independent cohort. Our findings suggest that SAMHD1 expression mediates doxorubicin resistance and may be an important prognostic biomarker in advanced, higher-risk DLBCL patients.
RESUMEN
The current standard-of-care treatment for glioblastoma includes DNA damaging agents, γ-irradiation (IR) and temozolomide (TMZ). These treatments fail frequently and there is limited alternative strategy. Therefore, identifying a new therapeutic target is urgently needed to develop a strategy that improves the efficacy of the existing treatments. Here, we report that tumor samples from GBM patients express a high level of SAMHD1, emphasizing SAMHD1's importance. The depletion of SAMHD1 using virus-like particles containing Vpx, VLP(+Vpx), sensitized two independent GBM cell lines (LN-229 and U-87) to veliparib, a well-established PARP inhibitor, and slowed cell growth in a dose-dependent manner. In the mouse GBM xenograft model, Vpx-mediated SAMHD1 depletion reduced tumor growth and SAMHD1 knockout (KO) improved survival. In combination with IR or TMZ, SAMHD1 KO and exposure to 50% growth inhibitory dose (gID50) of VLP(+Vpx) displayed a synergistic effect, resulting in impaired HR, and improved LN-229 cells' sensitivity to TMZ and IR. In conclusion, our finding demonstrates that SAMHD1 promotes GBM resistance to treatment, and it is a plausible therapeutic target to improve the efficacy of TMZ and IR in GBM. Furthermore, we show that Vpx could be a potential therapeutic tool that can be utilized to deplete SAMHD1 in GBM.
RESUMEN
OBJECTIVE: As germline genetic referral becomes increasingly routine as part of the care of newly diagnosed breast cancer patients, it is important to understand the psychosocial impact of genetic counseling at the time of diagnosis. We examined the psychosocial and quality of life (QOL) impact of providing proactive rapid genetic counseling and testing (RGCT) in the immediate aftermath of a breast cancer diagnosis. METHODS: We randomized 330 patients in a 2:1 ratio to proactive rapid genetic counseling (RGCT; N = 222) versus usual care (UC; N = 108). Participants completed a baseline telephone survey before randomization and definitive surgery and a follow-up survey at 1-month post-randomization. We evaluated the impact of RGCT versus UC on breast cancer genetic knowledge, distress, QOL, and decisional conflict. Given that 43% of UC participants and 86% of RGCT participants completed genetic counseling prior to the 1-month assessment, we also evaluated the impact of genetic counseling participation over and above group assignment. RESULTS: The RGCT intervention led to increased breast cancer genetic knowledge relative to UC but did not differentially impact other study outcomes. Across groups patients who participated in genetic counseling had significantly increased knowledge and improved QOL compared to those who did not participate in genetic counseling. CONCLUSIONS: While prior research has documented the impact of genetic counseling and testing on surgical decisions, these results confirm that participation in genetic counseling at the time of diagnosis can yield improvements in knowledge and QOL in the short-term.