Ranolazine in the treatment of atrial fibrillation: Results of the dose-ranging RAFFAELLO (Ranolazine in Atrial Fibrillation Following An ELectricaL CardiOversion) study

BACKGROUND

Currently available antiarrhythmic agents for the treatment of atrial fibrillation (AF) have important limitations, leaving an unmet need for safe and effective therapy. Ranolazine is an approved antianginal agent with a favorable safety profile and electrophysiologic properties suggesting a potential role in the treatment of AF.

OBJECTIVE

The purpose of this study was to assess the safety and efficacy of ranolazine in the prevention of AF recurrence after successful electrical cardioversion and to ascertain the most appropriate dose of this agent.

METHODS

This prospective, multicenter, randomized, double-blind, placebo-control parallel group phase II dose-ranging trial randomized patients with persistent AF (7 days to 6 months) 2 hours after successful electrical cardioversion to placebo, or ranolazine 375 mg, 500 mg, or 750 mg bid. Patients were monitored daily by transtelephonic ECG. The primary end-point was the time to first AF recurrence.

RESULTS

Of 241 patients randomized, 238 took at least 1 drug dose. Ranolazine proved to be safe and tolerable. No dose of the drug significantly prolonged time to AF recurrence. AF recurred in 56.4%, 56.9%, 41.7%, and 39.7% of patients in the placebo, ranolazine 375 mg, ranolazine 500 mg, and ranolazine 750 mg groups, respectively. The reduction in overall AF recurrence in the combined 500-mg and 750-mg groups was of borderline significance compared to the placebo group (P = .053) and significant compared to 375-mg group (P = .035).

CONCLUSION

No dose of ranolazine significantly prolonged time to AF recurrence. However, the 500-mg and 750 mg-groups combined reduced AF recurrences, suggesting a possible role for this agent in the treatment of AF.

Insulinotropic effect of high potassium concentration beyond plasma membrane depolarization

The question whether K⁺ depolarization is an appropriate experimental substitute for the physiological nutrient-induced depolarization of the β-cell plasma membrane was investigated using primary mouse β-cells and islets. At basal glucose 40 mM K⁺ induced a massive monophasic response, whereas 15 mM K⁺ had only a minimal insulinotropic effect, even though the increase in the cytosolic Ca²⁺ concentration ([Ca²⁺]i) was not inferior to that by 20 mM glucose. In voltage-clamp experiments, Ca²⁺ influx appeared as nifedipine-inhibitable inward action currents in the presence of sulfonylurea plus TEA to block compensatory outward K⁺ currents. Under these conditions, 15 mM K⁺ induced prolonged action currents and 40 mM K⁺ transformed the action current pattern into a continuous inward current. Correspondingly, 15 mM K⁺ led to an oscillatory increase and 40 mM K⁺ to a plateau of [Ca²⁺]i superimposed on the [Ca²⁺]i elevated by sulfonylurea plus TEA. Raising K⁺ to 15 or 40 mM in the presence of sulfonylurea (±TEA) led to a fast further increase of insulin secretion. This was reduced to basal levels by nifedipine or CoCl₂. The effects of 15 mM K⁺ on depolarization, action currents, and insulin secretion were mimicked by adding 35 mM Cs⁺ and those of 40 mM K⁺ by adding 35 mM Rb⁺, in parallel with their ability to substitute for K⁺ as permeant cation. In conclusion, the alkali metals K⁺, Rb⁺, or Cs⁺ concentration-dependently transform the pattern of Ca²⁺ influx into the β-cell and may thus generate stimuli of supraphysiological strength for insulin secretion.

Ca(2+)-dependent desensitization of insulin secretion by strong potassium depolarization

Depolarization by a high K(+) concentration is a widely used experimental tool to stimulate insulin secretion. The effects occurring after the initial rise in secretion were investigated here. After the initial peak a fast decline occurred, which was followed by a slowly progressive decrease in secretion when a strong K(+) depolarization was used. At 40 mM KCl, but not at lower concentrations, the decrease continued when the glucose concentration was raised from 5 to 10 mM, suggesting an inhibitory effect of the K(+) depolarization. When tolbutamide was added instead of the glucose concentration being raised, a complete inhibition down to prestimulatory values was observed. Equimolar reduction of the NaCl concentration to preserve isoosmolarity enabled an increase in secretion in response to glucose. Unexpectedly, the same was true when the Na(+)-reduced media were made hyperosmolar by choline chloride or mannitol. The insulinotropic effect of tolbutamide was not rescued by the compensatory reduction of NaCl, suggesting a requirement for activated energy metabolism. These inhibitory effects could not be explained by a lack of depolarizing strength or by a diminished free cytosolic Ca(2+) concentration ([Ca(2+)](i)). Rather, the complexation of extracellular Ca(2+) concomitant with the K(+) depolarization markedly diminished [Ca(2+)](i) and attenuated the inhibitory action of 40 mM KCl. This suggests that a strong but not a moderate depolarization by K(+) induces a [Ca(2+)](i)-dependent, slowly progressive desensitization of the secretory machinery. In contrast, the decline immediately following the initial peak of secretion may result from the inactivation of voltage-dependent Ca(2+) channels.

Efficacy and safety of olmesartan medoxomil 40 mg/hydrochlorothiazide 12.5 mg combination therapy versus olmesartan medoxomil 40 mg monotherapy in patients with moderate to severe hypertension: a randomized, double-blind, parallel-group, multicentre, multinational, phase III study

BACKGROUND

Current hypertension guidelines recommend using two antihypertensive agents when blood pressure (BP) control is not achieved with one single agent.

OBJECTIVE

This study was designed to assess the antihypertensive benefit of the olmesartan medoxomil 40 mg/hydrochlorothiazide (HCTZ) 12.5 mg combination versus olmesartan medoxomil 40 mg monotherapy in patients with moderate to severe hypertension.

METHODS

This was a randomized, double-blind, parallel-group, up-titration, multicentre, multinational, phase III study. Following a 2-week single-blind placebo run-in phase, 846 hypertensive patients with mean seated systolic BP (SeSBP) of 160-200 mmHg and mean seated diastolic BP (SeDBP) of 100-120 mmHg were randomized (1 : 2 ratio) to receive double-blind treatment with olmesartan medoxomil 40 mg or olmesartan medoxomil 40 mg/HCTZ 12.5 mg for 8 weeks (phase A). At week 8, patients not reaching BP goal (<140/90 mmHg; <130/80 mmHg in patients with diabetes mellitus) were up-titrated from olmesartan medoxomil 40 mg to olmesartan medoxomil 40 mg/HCTZ 12.5 mg or from olmesartan medoxomil 40 mg/HCTZ 12.5 mg to olmesartan medoxomil 40 mg/HCTZ 25 mg for an additional 8 weeks (phase B). Patients on goal continued their initial treatment. The primary efficacy parameter was the change in mean SeDBP during phase A.

RESULTS

Olmesartan medoxomil 40 mg/HCTZ 12.5 mg reduced mean SeDBP significantly more (-18.9 mmHg) than olmesartan medoxomil 40 mg (-15.8 mmHg) after 8 weeks of double-blind treatment (difference: -3.1 mmHg, p < 0.0001). Olmesartan medoxomil 40 mg/HCTZ 12.5 mg also reduced mean SeSBP significantly more than olmesartan medoxomil 40 mg (-5.4 mmHg, p < 0.0001). As a result, BP goal rates at week 8 were significantly higher with olmesartan medoxomil 40 mg/HCTZ 12.5 mg than with olmesartan medoxomil 40 mg (58.5% vs 44.3%; odds ratio 1.88; 95% CI 1.32, 2.54). During phase B, mean BP reductions were greater in patients up-titrated from olmesartan medoxomil 40 mg to olmesartan medoxomil 40 mg/HCTZ 12.5 mg than in those continuing on olmesartan medoxomil 40 mg (SeDBP: -9.3 mmHg vs -0.5 mmHg; SeSBP: -12.4 mmHg vs -0.5 mmHg). Similarly, mean BP reductions were greater in patients up-titrated from olmesartan medoxomil 40 mg/HCTZ 12.5 mg to olmesartan medoxomil 40 mg/HCTZ 25 mg than in those continuing on olmesartan medoxomil 40 mg/HCTZ 12.5 mg (SeDBP: -8.0 mmHg vs -0.3 mmHg; SeSBP: -12.1 mmHg vs -0.4 mmHg). In patients not on goal at week 8, addition of HCTZ 12.5 mg to olmesartan medoxomil 40 mg or up-titration from olmesartan medoxomil 40 mg/HCTZ 12.5 mg to olmesartan medoxomil 40 mg/HCTZ 25 mg brought additional patients to goal at week 16 (38.8% vs 36.9%). All treatments were well tolerated.

CONCLUSION

The olmesartan medoxomil 40 mg/HCTZ 12.5 mg combination is superior to olmesartan medoxomil 40 mg monotherapy in reducing SeDBP and SeSBP and increasing BP goal rates after 8 weeks. Patients not on goal at week 8 with olmesartan medoxomil 40 mg or olmesartan medoxomil 40 mg/HCTZ 12.5 mg benefited from adding HCTZ 12.5 mg or up-titrating to olmesartan medoxomil 40 mg/HCTZ 25 mg, respectively, confirming that up-titration is a clinically meaningful way to improve BP control. [

TRIAL REGISTRATION NUMBER

NCT00441350 (ClinicalTrials.gov Identifier)].

ER and PR Expression Profile of Circulating Tumor Cells in Metastatic Breast Cancer Patients in Comparison to the Primary Tumor

Background: Introduktion: Several studies have indicated that the expression of predictive markers including ER and PR can change during course of disease. Therefoore, reassesment of of the prediktive markers at the time of disease progression might help to optimize treatment decisions. Metastatic tissue may be difficult to obtain for repeated analysis. In this context, characterization of circulating tumor cells (CTCs) could be of relevance. Therefore, the purpose of the present study was: (1) to reevaluate the ER/PR expression by circulating tumor cells and (2) to compare the hormone receptor status expression profile of CTC with the primary tumor. Materials and Methods: We ecaluated, 166 blood samples from metastatic breast cancer patients at the time of first diagnosis of first metastatic disease or disease progression. All samples underwent immunomagnetic enrichment using the AdnaTest BreastCancerSelect (AdnaGen AG, Germany) within 4 hours after blood withdrawal followed by RNA isolation and subsequent gene expression analysis by reverse transcription and Multiplex-PCR in separated tumor cells using the AdnaTest BreastCancerDetect. CTC were analyzed for the three breast cancer associated markers: GA733-2, Muc-1, Her-2 and β-actin as an internal PCR control. Expression of the estrogen (ER) and progesterone (PR) receptor was assessed in an additional RT-PCR. The analysis of PCR products was performed by capillary electrophoresis on the Agilent Bioanalyzer 2100. Results: The overall detection rate for CTC was 38% (63/166 patients) with the expression rates of 79% for EpCAM (50/63 patients), 77% for MUC1 (49/63 patients), 49% for HER2 (31/63 patients), 23% for ER (15/65 patients) and 11% for PR (7/65 patients), respectively. Comparisons with the primary tumor were only performed in CTC+ patients (n=65). In 41 of 65 (63%) patients with ER+ tumors, CTC were ER- and 38/65 (58%) patients with PR+ tumors did not express PR on CTC. Primary tumors and CTC displayed a concordant ER and PR status in only 34% and 61% of cases, respectively. Conclusion: Most of the CTC were ER/PR-negative despite the presence of an ER/PR-positive primary tumor. The predictive value of hormone receptor status expression profile of CTC for palliative endocrine therapy has to be prospectively evaluated.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3009.