BackgroundResistance to temozolomide (TMZ) is due in part to enhanced DNA repair mediated by high expression of O6-methyl guanine DNA methyltransferase (MGMT) that is often characterised by unmethylated promoter. Here, we investigated pre-treatment of glioblastoma (GBM) cells with the 26S-proteasome inhibitor bortezomib (BTZ) as a strategy to interfere with MGMT expression and thus sensitise them to TMZ.MethodsCell lines and patient GBM-derived cells were examined in vitro, and the latter also implanted orthotopically into NOD-SCID C.B.-Igh-1b/lcrTac-Prkdc mice to assess efficacy and tolerability of BTZ and TMZ combination therapy. MGMT promoter methylation was determined using pyrosequencing and PCR, protein signalling utilised western blotting while drug biodistribution was examined by LC-MS/MS. Statistical analysis utilised Analysis of variance and the Kaplan–Meier method.ResultsPre-treatment with BTZ prior to temozolomide killed chemoresistant GBM cells with unmethylated MGMT promoter through MGMT mRNA and protein depletion in vitro without affecting methylation. Chymotryptic activity was abolished, processing of NFkB/p65 to activated forms was reduced and corresponded with low MGMT levels. BTZ crossed the blood–brain barrier, diminished proteasome activity and significantly prolonged animal survival.ConclusionBTZ chemosensitized resistant GBM cells, and the schedule may be amenable for temozolomide refractory patients with unmethylated MGMT promoter.

Background There are no data on the effect of low‐dose anticoagulation as secondary prophylaxis for venous thromboembolism (VTE) in cancer patients. We assessed the efficacy and safety of low‐dose apixaban for 30 months, after initial 6 months of full‐dose treatment. Methods We included 298 patients with cancer and any type of VTE in a single arm interventional clinical trial. All patients were treated with full‐dose apixaban (5 mg twice daily) for 6 months. Total 196 patients with active cancer after 6 months treatment continued with apixaban 2.5 mg twice daily for another 30 months. The main endpoints were recurrent VTE, major bleeding and clinically relevant non‐major bleeding. Results During the 30 months of treatment with low‐dose apixaban 14 (7.6%; 95% confidence interval (CI) 4.0%–11.7%) patients experienced recurrent VTE, six (3.1%; 95% CI 1.1%–6.5%) experienced major bleeding and 16 (8.1%, 95% CI: 4.7%–12.8%) experienced clinically relevant non‐major bleeding. The incidence rate per person month of recurrent VTE was 0.8% (95% CI 0.41–1.6) at 2–6 months with full‐dose apixaban, and 1.0% (95% CI 0.5–1.9) at 7–12 months with low‐dose apixaban. The incidence rate of major bleeding was 1.1% (95% CI 0.6–2.0) at 2–6 months, and 0.3% (95% CI 0.1–1.0) at 7–12 months. Between 12 and 36 months the incidence rate of recurrent VTE and major bleedings remained low. Conclusion Dose reduction of apixaban to 2.5 mg twice daily seems safe after 6 months of full‐dose treatment. After 12 months the incidence rate of recurrent VTE and major bleeding remained low.

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Background: Glioblastoma (GBM) is an aggressive malignant brain tumor where median survival is approximately 15 months after best available multimodal treatment. Recurrence is inevitable, largely due to O 6 methylguanine DNA methyltransferase (MGMT) that renders the tumors resistant to temozolomide (TMZ). We hypothesized that pretreatment with bortezomib (BTZ) 48 hours prior to TMZ to deplete MGMT levels would be safe and tolerated by patients with recurrent GBM harboring unmethylated MGMT promoter. The secondary objective was to investigate whether 26S proteasome blockade may enhance differentiation of cytotoxic immune subsets to impact treatment responses measured by radiological criteria and clinical outcomes. Methods: Ten patients received intravenous BTZ 1.3 mg/m 2 on days 1, 4, and 7 during each 4th weekly TMZ-chemotherapy starting on day 3 and escalated from 150 mg/m 2 per oral 5 days/wk via 175 to 200 mg/m 2 in cycles 1, 2, and 3, respectively. Adverse events and quality of life were evaluated by CTCAE and EQ-5D-5L questionnaire, and immunological biomarkers evaluated by flow cytometry and Luminex enzyme-linked immunosorbent assay. Results: Sequential BTZ + TMZ therapy was safe and well tolerated. Pain and performance of daily activities had greatest impact on patients' self-reported quality of life and were inversely correlated with Karnofsky performance status. Patients segregated a priori into three groups, where group 1 displayed