Phase Ib Study of Ribociclib plus Fulvestrant and Ribociclib plus Fulvestrant plus PI3K Inhibitor (Alpelisib or Buparlisib) for HR+ Advanced Breast Cancer.

PURPOSE: Resistance to treatment with endocrine therapy in patients with HR+, HER2- advanced breast cancer (ABC) is common and dual inhibition of CDK4/6 and PI3K pathways may delay the development of resistance. This phase Ib trial evaluates the safety and tolerability of triple and double regimens containing the CDK4/6 inhibitor ribociclib. PATIENTS AND METHODS: In this open-label, multicenter, phase Ib study, 70 postmenopausal women with HR+, HER2- ABC were enrolled into one of four treatment combinations: ribociclib (once daily, 3 weeks on, 1 week off) plus fulvestrant; ribociclib (continuous dosing) plus fulvestrant; ribociclib plus alpelisib plus fulvestrant; or ribociclib plus buparlisib plus fulvestrant. RESULTS: The recommended phase II dose (RP2D) of ribociclib was confirmed to be 600 mg (3 weeks on, 1 week off) and 400 mg (continuous dosing) plus fulvestrant 500 mg. For the triple combination with buparlisib, the RP2D was ribociclib 400 mg plus buparlisib 30 mg plus fulvestrant 500 mg. Enrollment for the triple combinations was stopped due to unexpected toxicity. No RP2D was determined for the alpelisib combination. The safety profiles of the ribociclib plus fulvestrant combinations were consistent with those in previous studies. There was no marked difference in ribociclib exposure in the presence of triple-combination partners. The highest overall response rate was seen in the buparlisib triple combination (25.0%; 95% confidence interval, 9.8-46.7). CONCLUSIONS: Ribociclib plus fulvestrant demonstrated safety in the treatment of patients with HR+, HER2- ABC. Triple combinations with alpelisib or buparlisib plus fulvestrant are not recommended for phase II investigation.See related commentary by Clark et al., p. 371.

Evaluation of Absolute Oral Bioavailability and Bioequivalence of Ribociclib, a Cyclin-Dependent Kinase 4/6 Inhibitor, in Healthy Subjects.

Ribociclib, a selective and potent cyclin-dependent kinase 4/6 inhibitor, has demonstrated safety and efficacy in combination with endocrine therapy in hormone receptor-positive, human epidermal growth factor receptor-2-negative advanced breast cancer. In 2 open-label crossover studies in healthy participants, the absolute bioavailability of a single oral dose of a ribociclib 600-mg tablet (n = 16) was compared with a single intravenous ribociclib infusion of 150 mg (n = 16), and the bioequivalence of a ribociclib 600-mg tablet (n = 31) and a ribociclib 600-mg capsule (n = 31) was evaluated. The pharmacokinetics of ribociclib and its major metabolite, LEQ803, were assessed in both studies. The oral bioavailability of the 600-mg ribociclib tablet was 65.8% (90% confidence interval [CI], 59.1-73.2%). The geometric mean systemic clearance of ribociclib was moderate (40.2 L/h; 27.4% intersubject variability [CV%]) compared with hepatic blood flow, and the geometric mean volume of distribution was high (979 L; 25.2 CV%). LEQ803-to-ribociclib metabolic ratios were 0.198 for the oral administration and 0.125 for intravenous infusion. Bioequivalence of the tablet and capsule formulations was demonstrated for ribociclib. The geometric mean ratios of maximum concentration and area under the curve from time 0 to last quantifiable concentration and to infinity were 1.01, 1.00, and 0.937, respectively, within the predefined bioequivalence range of 0.80 to 1.25. The median time to reach maximum concentration was 3 hours with both formulations. No serious adverse events were observed in either study.

Primary angiosarcoma of the breast: Case report of a rare vascular tumor.

This is a case report of a woman in her sixth decade of life diagnosed with primary angiosarcoma of the breast using mammography and ultrasound, confirmed with imaging-guided biopsy, and finally treated with surgery and radiation. Imaging studies obtained and discussed include mammography, ultrasonography, and MRI. Further discussion on the presenting symptoms, useful imaging modalities, and treatment options takes place. It is important to consider primary angiosarcoma of the breast, though rare, in any woman presenting with a palpable breast mass and, if feasible, an MRI will be most helpful in the diagnosis of this rare tumor.

Losartan may inhibit the progression of liver fibrosis in chronic HCV patients.

BACKGROUND: Abundant experimental evidence indicates overproduction of angiotensin II in the injured liver, and a role in stimulation of hepatic stellate cell (HSC) activation and fibrogenesis thereby, representing an attractive antifibrotic target. The aim of this study was to examine the antifibrotic effect of losartan on histopathologic level in chronic HCV patients. METHODS: A prospective study on fifty patients with chronic HCV and liver fibrosis proved by liver biopsy was conducted. They included patients who did not respond (n=36) or comply (n=2) or receive therapy due to established cirrhosis (n=10), or refused to receive (n=2) combined interferon and ribavirin therapy. They were divided randomly into 2 groups. The 1(st) group (n=25) was given losartan 50 mg OD for 1 year and the 2(nd) group (25 patients) was given silymarin, 140 mg t.i.d., (silymarin group). Liver biopsy was done at baseline and 1 year from the onset of treatment (end of study). RESULTS: In the second liver biopsy after 1 year, the decrease in fibrosis stage was significantly different between losartan group and silymarin group (a decrease of 1.88±0.96 (50.9%) vs. 0.45±0.93 (11.7%), respectively; P<0.01). In patients treated with losartan, regression in fibrosis stage was observed in 14/16 patients vs. 2/11 in silymarin group (P<0.01). No differences were observed in inflammation grades in both groups. A significant increase in albumin and prothrombin levels and a decrease in systolic blood pressure were found in losartan but not in silymarin group (P=0.009, 0.001 & 0.018 respectively and P=0.158, 0.603 & 0.288, respectively). CONCLUSIONS: Histopathological scores showed that losartan had an inhibitory effect on progression and even led to regression of fibrosis stage but had no effect on the grade of inflammation.

Efavirenz Inhibits the Human Ether-A-Go-Go Related Current (hERG) and Induces QT Interval Prolongation in CYP2B6*6*6 Allele Carriers.

BACKGROUND: Efavirenz (EFV) has been associated with torsade de pointes despite marginal QT interval lengthening. Since EFV is metabolized by the cytochrome P450 (CYP) 2B6 enzyme, we hypothesized that EFV would lengthen the rate-corrected QT (QTcF) interval in carriers of the CYP2B6*6 decreased functional allele. OBJECTIVE: The primary objective of this study was to evaluate EFV-associated QT interval changes with regard to CYP2B6 genotype and to explore mechanisms of QT interval lengthening. METHODS: EFV was administered to healthy volunteers (n = 57) as a single 600 mg dose followed by multiple doses to steady-state. Subjects were genotyped for known CYP2B6 alleles and ECGs and EFV plasma concentrations were obtained serially. Whole-cell, voltage-clamp experiments were performed on cells stably expressing hERG and exposed to EFV in the presence and absence of CYP2B6 expression. RESULTS: EFV demonstrated a gene-dose effect and exceeded the FDA criteria for QTcF interval prolongation in CYP2B6*6/*6 carriers. The largest mean time-matched differences ∆∆QTcF were observed at 6 hours (14 milliseconds; 95% CI [1; 27]), 12 hours (18 milliseconds; 95% CI [-4; 40]), and 18 hours (6 milliseconds; 95% CI [-1; 14]) in the CYP2B6*6/*6 genotype. EFV concentrations exceeding 0.4 µg/mL significantly inhibited outward hERG tail currents (P < 0.05). CONCLUSIONS: This study demonstrates that homozygous carriers of CYP2B6*6 allele may be at increased risk for EFV-induced QTcF interval prolongation via inhibition of hERG.