Effects of orally administered crofelemer on the incidence and severity of neratinib-induced diarrhea in female dogs.

Targeted therapies have increased cancer therapy-related diarrhea (CTD) burden, with high incidence and/or severity of diarrhea for some agents that inhibit epidermal growth factor receptor and receptor tyrosine kinases. Neratinib is a pan-HER tyrosine kinase inhibitor approved for breast cancer treatment and causes severe diarrhea in >95% of patients. Crofelemer, a novel intestinal chloride ion channel modulator, is an approved antidiarrheal drug for symptomatic relief of noninfectious diarrhea in patients with HIV/AIDS receiving antiretroviral therapy. The objective of this study was to evaluate the effectiveness of crofelemer prophylaxis in reducing the incidence /severity of neratinib-induced diarrhea without concomitant administration of loperamide in female beagle dogs. A pilot study using 3 dogs determined a maximum daily tolerated dose of neratinib was between 40 and 80 mg; this dose would induce a consistent incidence/severity of diarrhea without risking severe dehydration. In the definitive study, 24 female beagle dogs (8/group) received neratinib once daily and placebo capsules (CTR) four times/day, or neratinib once daily and crofelemer 125 mg delayed-release tablets given two times (BID), or neratinib once daily and crofelemer 125 mg delayed-release tablets given four times per day (QID). Fecal scores were collected twice daily using an established canine stool scoring scale called the Purina Fecal Scoring (PFS) System. After 28 days, using analysis of covariance (ANCOVA), dogs in the CTR group had a significantly higher average number of weekly loose/watery stools (PFS of 6 or 7) when compared to either crofelemer BID (8.71±2.2 vs. 5.96±2.2, p = 0.028) or crofelemer QID (8.70±2.2 vs. 5.74±2.2, p = 0.022) treatment groups. The average number of weekly loose/watery stools were not different between the crofelemer BID and QID treatment groups (p = 0.84). This study showed that crofelemer prophylaxis reduced the incidence/severity of neratinib-associated diarrhea in female beagle dogs without the need for any loperamide administration.

Process Development and Scale-up Total Synthesis of Largazole, a Potent Class I Histone Deacetylase Inhibitor.

Herein we describe the research and development of the process for the scale-up total synthesis of largazole, a potent class I selective histone deacetylase (HDAC) inhibitor, a potential anticancer agent and also useful for the treatment of other disorders where transcriptional reprogramming might be beneficial. The synthetic route and conditions for each fragment and final product were modified and optimized to make them suitable for larger scale synthesis. With the process we developed, hundreds of grams of each fragment and decagrams of final productlargazole were synthesized in good to excellent yields. The final target largazole was obtained in 21% overall yield over eight steps based on the longest sequence with over 95% HPLC purity.

The future of drug development: advancing clinical trial design.

Declining pharmaceutical industry productivity is well recognized by drug developers, regulatory authorities and patient groups. A key part of the problem is that clinical studies are increasingly expensive, driven by the rising costs of conducting Phase II and III trials. It is therefore crucial to ensure that these phases of drug development are conducted more efficiently and cost-effectively, and that attrition rates are reduced. In this article, we argue that moving from the traditional clinical development approach based on sequential, distinct phases towards a more integrated view that uses adaptive design tools to increase flexibility and maximize the use of accumulated knowledge could have an important role in achieving these goals. Applications and examples of the use of these tools--such as Bayesian methodologies--in early- and late-stage drug development are discussed, as well as the advantages, challenges and barriers to their more widespread implementation.

Evaluation of crofelemer in the treatment of diarrhea-predominant irritable bowel syndrome patients.

BACKGROUND: Crofelemer improves bowel function in several conditions characterized by states of prominent secretory diarrhea. AIM: This double-blind, randomized, placebo-controlled trial evaluated the effects of 3 dose levels of crofelemer in patients with diarrhea-predominant irritable bowel syndrome (D-IBS). METHODS: Male and female patients were randomly assigned to receive crofelemer 125, 250 or 500 mg or placebo twice daily for 12 weeks. The primary efficacy measure was a responder for improvement in stool consistency. In addition, abdominal pain- and discomfort-free days, pain and discomfort scores as well as other bowel function parameters (such as stool frequency and consistency, urgency, bloating) were evaluated. RESULTS: Two hundred and forty-two D-IBS patients were randomized. Crofelemer did not produce significant improvement in stool consistency (primary endpoint), stool frequency, urgency or adequate relief. However, female D-IBS patients showed improvement in the proportion of pain- and discomfort-free days during treatment with 500 mg crofelemer: month 1 (crofelemer vs. placebo: 17.7 vs. 10.2%, p = 0.098); month 2 (23.5 vs. 13.3%, p = 0.076); month 3 (26.1 vs. 10.6%, p = 0.0076). No benefit was seen in male D-IBS patients. Crofelemer was well tolerated. CONCLUSIONS: Crofelelmer did not produce benefit on bowel function; an increase in the number of pain- and discomfort-free days in female D-IBS patients was seen. Further studies with crofelemer are warranted to evaluate it as a potential visceral analgesic.

Preclinical profile of VX-950, a potent, selective, and orally bioavailable inhibitor of hepatitis C virus NS3-4A serine protease.

VX-950 is a potent, selective, peptidomimetic inhibitor of the hepatitis C virus (HCV) NS3-4A serine protease, and it demonstrated excellent antiviral activity both in genotype 1b HCV replicon cells (50% inhibitory concentration [IC50] = 354 nM) and in human fetal hepatocytes infected with genotype 1a HCV-positive patient sera (IC50 = 280 nM). VX-950 forms a covalent but reversible complex with the genotype 1a HCV NS3-4A protease in a slow-on, slow-off process with a steady-state inhibition constant (K(i)*) of 7 nM. Dissociation of the covalent enzyme-inhibitor complex of VX-950 and genotype 1a HCV protease has a half-life of almost an hour. A >4-log10 reduction in the HCV RNA levels was observed after a 2-week incubation of replicon cells with VX-950, with no rebound of viral RNA observed after withdrawal of the inhibitor. In several animal species, VX-950 exhibits a favorable pharmacokinetic profile with high exposure in the liver. In a recently developed HCV protease mouse model, VX-950 showed excellent inhibition of HCV NS3-4A protease activity in the liver. Therefore, the overall preclinical profile of VX-950 supports its candidacy as a novel oral therapy against hepatitis C.