Magnetic Resonance Imaging of Cerebral Small Vessel Disease in Men Living with HIV and HIV-Negative Men Aged 50 and Above

We assessed whether HIV status was associated with white matter hyperintensities (WMH), a neuroimaging correlate of cerebral small vessel disease (CSVD), in men aged ≥50 years. A cross-sectional substudy was nested within a larger cohort study. Virologically suppressed men living with HIV (MLWH) and demographically matched HIV-negative men aged ≥50 underwent magnetic resonance imaging (MRI) at 3 Tesla. Sequences included volumetric three-dimensional (3D) T1-weighted, fluid-attenuated inversion recovery and pseudocontinuous arterial spin labeling. Regional segmentation by automated image processing algorithms was used to extract WMH volume (WMHV) and resting cerebral blood flow (CBF). The association between HIV status and WMHV as a proportion of intracranial volume (ICV; log-transformed) was estimated using a multivariable linear regression model. Thirty-eight MLWH [median age 59 years (interquartile range, IQR 55-64)] and 37 HIV-negative [median 58 years (54-63)] men were analyzed. MLWH had median CD4⁺ count 570 (470-700) cells/μL and a median time since diagnosis of 20 (14-24) years. Framingham 10-year risk of cardiovascular disease was 6.5% in MLWH and 7.4% in controls. Two (5%) MLWH reported a history of stroke or transient ischemic attack and five (13%) reported coronary heart disease compared with none of the controls. The total WMHV in MLWH was 1,696 μL (IQR 1,229-3,268 μL) or 0.10% of ICV compared with 1,627 μL (IQR 1,032-3,077 μL), also 0.10% of ICV in the HIV-negative group (p = .43). In the multivariable model, WMHV/ICV was not associated with HIV status (p = .86). There was an age-dependent decline in cortical CBF [-3.9 mL/100 mL/min per decade of life (95% confidence interval 1.1-6.7 mL)] but no association between CBF and HIV status (p > .2 in all brain regions analyzed). In conclusion, we found no quantitative MRI evidence of an increased burden of CSVD in MLWH aged 50 years and older.

Phase I and pharmacodynamic study of an orally administered novel inhibitor of histone deacetylases, SB939, in patients with refractory solid malignancies

BACKGROUND

The objective of this study was to assess the safety, maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics, and preliminary efficacy of SB939, a novel histone deacetylase (HDAC) inhibitor, in patients with advanced solid malignancies.

PATIENTS AND METHODS

Dose-escalating cohorts of three to six patients received SB939 orally thrice weekly for 3 weeks in a 4-week cycle. Acetylated histone H3 (acH3) was measured in peripheral blood mononuclear cells (PBMCs).

RESULTS

Thirty patients treated at one of five doses (10-80 mg/day) received 79 cycles of SB939 (range, 1-12 cycles). Dose-limiting toxic effects were fatigue, hypokalemia, troponin T elevation, and QTc prolongation. Peak plasma concentration (C(max)) and area under the concentration-time curve extrapolated to infinity increased dose proportionally. The MTD of SB939 was 80 mg/day. The mean elimination half-life and oral clearance of SB939 were 7.2 ± 0.6 h and 53.0 ± 8.5 l/h, respectively, with no substantial accumulation on day 15. An increase in acH3 was observed at hour 3 and correlated with dose and C(max). Stable disease was seen in several tumor types treated at ≥40 mg. HDAC inhibition was consistently observed at 60 mg, the recommended dose.

CONCLUSIONS

SB939 can be safely administered at the recommended dose and reaches plasma levels that strongly inhibit HDAC in PBMCs. These data support further efficacy studies of SB939.

Phase I study of SB939 three times weekly for 3 weeks every 4 weeks in patients with advanced solid malignancies

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Background: SB939 is a novel orally bioavailable inhibitor of class 1 and 2 histone deacetylases. We conducted a phase I study to assess the safety, maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics and preliminary efficacy of SB939 in patients with advanced solid malignancies. Methods: SB939 was administered orally every other day 3 times a week for 3 consecutive weeks, in a 4-week cycle. Cohorts of patient were treated with escalating doses of SB939 starting from 10 mg. PK and PD (Acetylated Histone 3 in PBMCs) samples were collected in the first cycle. Results: 31 patients were enrolled at 10 mg (n=3), 20 mg (4), 40 mg (8), 60 mg (10) and 80 mg (6). The median number of treatment cycles received was 3.6. Fatigue, elevation of troponin T and QTc prolongation were the observed dose-limiting toxicities (DLT). At 80mg, one patient each (3/6) experienced a DLT of grade 3 fatigue, grade 3 asymptomatic elevation of troponin T and grade 3 QTc prolongation respectively. All DLTs were reversible and no treatment mortality was observed. Grade 1–2 fatigue occurred in 56% of patients occurring mainly at the 4th week, and 37% of pts had G1–2 anorexia. Grade 3–4 thrombocytopenia was observed in 2 patients at 60 mg at cycles 1 and 6 of treatment. SB939 was rapidly absorbed reaching Tmax between 1–3 h after ingestion, and mean elimination half-life and oral clearance of SB939 were 7.2 + 0.6 hrs and 53 + 8.5 L/h respectively. Cmax and AUC (0-∞) were dose-proportionally increased at this dose range. There was no substantial accumulation of SB939 on day 15 following repeated dosing. Concentrations above IC50 of SB939 for HDAC I was reached at all doses. Acetylation of H3 was dose dependent and consistent at 60mg. Of the 13 patients evaluable for response, stable disease was seen in 1 patient with follicular thyroid carcinoma and 1 with hepatocellular carcinoma for 51 and 164 days respectively. Conclusions: SB939 has similar toxicity profiles as that of other HDAC inhibitors and a favorable PK/PD profile. The MTD of SB939 in this regimen was 80 mg and 60mg is the recommended dose, at which acetylation of H3 is consistently observed. Further phase 2 studies with SB939 in specific indications are being planned.

No significant financial relationships to disclose.