1. This study was designed to evaluate how the absence of P-glycoprotein (Pgp, Mdr1a), breast cancer-resistance protein (Bcrp, Abcg2) or both affects drug distribution into sciatic nerves, brain and cerebrospinal fluid (CSF) in rats. 2. Pgp substrate (loperamide), BCRP substrates (dantrolene and proprietary compound X) and dual substrates (imatinib and proprietary compound Y) were well distributed into sciatic nerves with comparable nerve to plasma concentration ratios between wild-type and knockout (KO) rats. 3. Brain exposure increased substantially in Mdr1a(-/-) rats for loperamide and in Mdr1a(-/-)/Abcg2(-/-) rats for imatinib and compound Y, but minimally to modestly in Abcg2(-/-) rats for dantrolene and compound X. The deletion of Mdr1a or Abcg2 alone had little effect on brain distribution of compound Y. 4. While CSF to unbound brain concentration ratio remained ≥3 in the KO animals for dantrolene, compounds X and Y, it was reduced to 1 in the Mdr1a(-/-)/Abcg2(-/-) rats for imatinib. 5. The data indicate that Pgp and Bcrp do not play significant roles in drug distribution into peripheral nerve tissues in rats, while working in concert to regulate brain penetration. Our results further support that CSF concentration may not be a good surrogate for unbound brain concentration of efflux substrates.

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Oncolytic immunotherapies represent a new promising strategy in the treatment of cancer. In our efforts to develop oncolytic peptides, we identified a series of chemically modified 9-mer cationic peptides that were highly effective against both drug-resistant and drug-sensitive cancer cells and with lower toxicity toward normal cells. Among these peptides, LTX-315 displayed superior anticancer activity and was selected as a lead candidate. This peptide showed relative high plasma protein binding abilities and a human plasma half-life of 160 min, resulting in formation of nontoxic metabolites. In addition, the lead candidate demonstrated relatively low ability to inhibit CYP450 enzymes. Collectively these data indicated that this peptide has potential to be developed as a new anticancer agent for intratumoral administration and is currently being evaluated in a phase I/IIa study.

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Women with breast cancer frequently develop painful bone metastases. This retrospective study was designed to longitudinally characterize patterns of patient-reported symptoms among patients with breast cancer relative to the diagnosis of bone metastases.
Patient records were identified from the Oncology Services Comprehensive Electronic Records (OSCER) database which includes outpatient oncology practices across the USA. Symptom burden was assessed by Patient Care Monitor (PCM) assessments, which are administered as part of routine care in a subset of these practices. Eligible patients were women diagnosed with breast cancer (ICD-9-CM 174.xx) who developed bone metastases (ICD-9-CM 198.5) and had ≥1 PCM assessment between January 2007 and December 2012. The pre-specified endpoint was the occurrence of moderate to severe symptom burden, defined as PCM score ≥4 (0-10 scale).
One thousand one hundred five women (median age, 61) met the eligibility criteria. Worsening of symptoms, particularly fatigue and pain, occurred in the months leading up to the diagnosis of bone metastases. After bone metastases diagnosis, the rate of increase in the proportion of patients experiencing moderate/severe symptoms slowed, but continued to climb during follow-up. Median time to moderate/severe symptoms was 0.9 month for fatigue, 1 month for pain, 2.9 months for trouble sleeping, and 7.7 months for numbness/tingling. Half of the patients received bone-targeted agents after diagnosis of bone metastases.
Symptom burden, especially pain and fatigue, increased both before and after the diagnosis of bone metastases, highlighting the need for proactive monitoring and management of symptoms in breast cancer patients.

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Delamanid (Deltyba; OPC-67683) is the first approved drug in a novel class of nitro-dihydro-imidazooxazoles developed for the treatment of multidrug-resistant tuberculosis. Patients with tuberculosis require treatment with multiple drugs, several of which have known drug-drug interactions. Transporters regulate drug absorption, distribution and excretion; therefore, the inhibition of transport by one agent may alter the pharmacokinetics of another, leading to unexpected adverse events. Therefore, it is important to understand how delamanid affects transport activity. In the present study, the potencies of delamanid and its main metabolites as substrates and inhibitors of various transporters were evaluated in vitro. Delamanid was not transported by the efflux ATP-binding cassette (ABC) transporters P-glycoprotein (MDR1/ABCB1) and breast cancer resistance protein (BCRP/ABCG2), solute carrier (SLC) transporters, organic anion transporting polypeptides or organic cation transporter 1. Similarly, metabolite M1 was not a substrate for any of these transporters except P-gp. Delamanid showed no inhibitory effect on ABC transporters MDR1, BCRP and the bile salt export pump (BSEP, ABCB11), SLC transporters or organic anion transporters. Metabolites M1 and M2 inhibited P-gp- and BCRP-mediated transport, but only at IC50values (M1: 4.65 and 5.71 μmol/L; M2: 7.80 and 6.02 μmol/L), well above corresponding Cmaxvalues observed following multiple dosing in clinical trials. Metabolites M3 and M4 did not affect the activities of any transporters tested. These in vitro data suggest that delamanid is unlikely to have clinically relevant interactions with drugs for which absorption and disposition are mediated by this group of transporters.
Copyright © 2016, American Society for Microbiology. All Rights Reserved.

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Fulvestrant is an estrogen receptor (ER) antagonist administered to breast cancer patients by monthly intramuscular injection. Given its present limitations of dosing and route of administration, a more flexible orally available compound has been sought to pursue the potential benefits of this drug in patients with advanced metastatic disease. Here we report the identification and characterization of AZD9496, a non-steroidal small molecule inhibitor of ERα which is a potent and selective antagonist and down-regulator of ERα in vitro and in vivo in ER-positive models of breast cancer. Significant tumour growth inhibition was observed as low as 0.5 mg/kg dose in the estrogen-dependent MCF-7 xenograft model, where this effect was accompanied by a dose-dependent decrease in PR protein levels demonstrating potent antagonist activity. Combining AZD9496 with PI3K pathway and CDK4/6 inhibitors led to further growth inhibitory effects compared to monotherapy alone. Tumour regressions were also seen in a long-term estrogen-deprived breast model, where significant down-regulation of ERα protein was observed. AZD9496 bound and down-regulated clinically relevant ESR1 mutants in vitro and inhibited tumour growth in an ESR1-mutant patient-derived xenograft model that included a D538G mutation. Collectively, the pharmacological evidence showed that AZD9496 is an oral, non-steroidal, selective estrogen receptor antagonist and down-regulator in ER-positive breast cells that could provide meaningful benefit to ER-positive breast cancer patients. AZD9496 is currently being evaluated in a Phase 1 clinical trial.
Copyright ©2016, American Association for Cancer Research (AACR) (Free AACR Whitepaper).

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