Discovery of N-methyl-4-(4-methoxyanilino)quinazolines as potent apoptosis inducers. Structure-activity relationship of the quinazoline ring.

As a continuation of our efforts to discover and develop apoptosis inducing N-methyl-4-(4-methoxyanilino)quinazolines as novel anticancer agents, we explored substitution at the 5-, 6-, 7-positions of the quinazoline and replacement of the quinazoline by other nitrogen-containing heterocycles. A small group at the 5-position was found to be well tolerated. At the 6-position a small group like an amino was preferred. Substitution at the 7-position was tolerated much less than at the 6-position. Replacing the carbon at the 8-position or both the 5- and 8-positions with nitrogen led to about 10-fold reductions in potency. Replacement of the quinazoline ring with a quinoline, a benzo[d][1,2,3]triazine, or an isoquinoline ring showed that the nitrogen at the 1-position is important for activity, while the carbon at the 2-position can be replaced by a nitrogen and the nitrogen at the 3-position can be replaced by a carbon. Through the SAR study, several 5- or 6-substituted analogs, such as 2a and 2c, were found to have potencies approaching that of lead compound N-(4-methoxyphenyl)-N,2-dimethylquinazolin-4-amine (1g, EP128495, MPC-6827, Azixa).

Carbamazepine pharmacokinetics are not affected by zonisamide: in vitro mechanistic study and in vivo clinical study in epileptic patients.

Carbamazepine is metabolized by CYP3A4 and several other cytochrome P450 enzymes. The potential effects of zonisamide on carbamazepine pharmacokinetics (PK) have not been well characterized, with contradictory literature reports. Hence, an in vitro study was designed to evaluate the cytochrome P450 inhibition spectrum of zonisamide using human liver microsomes. Further, an in vivo steady-state study was performed to measure the effect of zonisamide on carbamazepine PK in epileptic patients, and monitor zonisamide PK. In vitro human liver microsomes were incubated with zonisamide (200, 600 or 1000 microM) in the presence of appropriate probe substrates to assess selected cytochrome P450 activities. In vivo, the effect of zonisamide, up to 400 mg/day, on the steady-state PK of carbamazepine and carbamazepine-epoxide (CBZ-E) was studied in 18 epileptic patients. In vitro, zonisamide did not inhibit CYP1A2 and 2D6, and only weakly inhibited CYP2A6, 2C9, 2C19, and 2E1. The estimated Ki for zonisamide inhibition of CYP3A4 was 1076 microM, 12 times higher than typical unbound therapeutic serum zonisamide concentrations. In vivo, no statistically significant differences were observed for mean Cmax, Tmax, and AUC0-12 of total and free carbamazepine and CBZ-E measured before and after zonisamide administration (300-400 mg/day for 14 days). However, CBZ-E renal clearance was significantly (p < 0.05) reduced by zonisamide. The observed mean zonisamide t1/2 (36.3h), relative to approximately 65 h reported in subjects on zonisamide monotherapy, reflects known CYP3A4 induction by carbamazepine. Based on the lack of clinically relevant in vitro and in vivo effects, adjustment of carbamazepine dosing should not be required with concomitant zonisamide administration.

Phase I clinical trial of MPC-6827 (Azixa), a microtubule destabilizing agent, in patients with advanced cancer.

MPC-6827 (Azixa) is a small-molecule microtubule-destabilizing agent that binds to the same (or nearby) sites on ß-tubulin as colchicine. This phase I study was designed to determine the dose-limiting toxicities (DLT), maximum tolerated dose (MTD), and pharmacokinetics (PK) of MPC-6827 in patients with solid tumors. Patients with advanced/metastatic cancer were treated with once-weekly, 1- to 2-hour intravenous administration of MPC-6827 for 3 consecutive weeks every 28 days (1 cycle). Dose escalation began with 0.3, 0.6, 1, and 1.5 mg/m(2), with subsequent increments of 0.6 mg/m(2) until the MTD was determined. A 3 + 3 design was used. Pharmacokinetics of MPC-6827 and its metabolite MPI-0440627 were evaluated. Forty-eight patients received therapy; 79 cycles were completed (median, 1; range, 1-10). The most common adverse events were nausea, fatigue, flushing, and hyperglycemia. The DLT was nonfatal grade 3 myocardial infarction at 3.9 mg/m(2) (1/6 patients) and at 4.5 mg/m(2) (1/7 patients). The MTD was determined to be 3.3 mg/m(2) (0/13 patients had a DLT). Five (10.4%) of the 48 patients achieved stable disease (Response Evaluation Criteria in Solid Tumors) for 4 months or greater. MPC-6827 has a high volume of distribution and clearance. Half-life ranged from 3.8 to 7.5 hours. In conclusion, MPC-6827 administered intravenously over 2 hours at a dose of 3.3 mg/m(2) once weekly for 3 weeks every 28 days was safe in patients with heavily pretreated cancer. Clinical trials with MPC-6827 and chemotherapy are ongoing.

Discovery of N-(4-methoxyphenyl)-N,2-dimethylquinazolin-4-amine, a potent apoptosis inducer and efficacious anticancer agent with high blood brain barrier penetration.

As a continuation of our structure-activity relationship (SAR) studies on 4-anilinoquinazolines as potent apoptosis inducers and to identify anticancer development candidates, we explored the replacement of the 2-Cl group in our lead compound 2-chloro-N-(4-methoxyphenyl)-N-methylquinazolin-4-amine (6b, EP128265, MPI-0441138) by other functional groups. This SAR study and lead optimization resulted in the identification of N-(4-methoxyphenyl)-N,2-dimethylquinazolin-4-amine (6h, EP128495, MPC-6827) as an anticancer clinical candidate. Compound 6h was found to be a potent apoptosis inducer with EC(50) of 2 nM in our cell-based apoptosis induction assay. It also has excellent blood brain barrier penetration, and is highly efficacious in human MX-1 breast and other mouse xenograft cancer models.

Discovery of 2-chloro-N-(4-methoxyphenyl)-N-methylquinazolin-4-amine (EP128265, MPI-0441138) as a potent inducer of apoptosis with high in vivo activity.

Using a live cell, high-throughput caspase-3 activator assay, we have identified a novel series of 4-anilinoquinazolines as inducers of apoptosis. In this report, we discuss the discovery of 2-chloro-N-(4-methoxyphenyl)-N-methylquinazolin-4-amine, compound 2b (EP128265, MPI-0441138) as a highly active inducer of apoptosis (EC50 for caspase activation of 2 nM) and as a potent inhibitor of cell proliferation (GI50 of 2 nM) in T47D cells. Compound 2b inhibited tubulin polymerization, was effective in cells overexpressing ABC transporter Pgp-1, and was efficacious in the MX-1 human breast and PC-3 prostate cancer mouse models. In contrast to the SAR of 4-anilinoquinazolines as EGFR kinase inhibitors, the methyl group on the nitrogen linker was essential for the apoptosis-inducing activity of 4-anilinoquinazolines and substitution in the 6- and 7-positions of the quinazoline core structure decreased potency.

Safety, tolerability, pharmacokinetics, and Abeta levels after short-term administration of R-flurbiprofen in healthy elderly individuals.

To evaluate the safety and tolerability and pharmacokinetic properties of R-flurbiprofen (Tarenflurbil) in normal elderly individuals and to determine the effect of the drug on amyloid beta 42 (Abeta42) levels, we conducted a double-blind, placebo-controlled study of 48 healthy subjects aged 55 to 80. Three successive cohorts were randomized to doses of 400, 800, or 1600 mg/d, or placebo, given as 2 divided doses for 21 days. Blood and cerebrospinal fluid were collected for pharmacokinetic studies and measurement of Abeta levels at baseline and on day 21. R-flurbiprofen was well-tolerated at all 3 doses. The compound penetrated the blood-brain barrier in a dose-dependent manner. From baseline to 21 days, comparisons between study groups revealed no significant differences in changes of cerebrospinal fluid Abeta42 levels and no significant differences in changes of plasma Abeta42 levels at the time of trough drug level at 21 days of treatment. Further analysis of drug concentration-response for plasma samples showed that at the time of peak plasma concentration, higher plasma drug concentration was related to lower Abeta42 plasma levels (P=0.016). R-flurbiprofen had an excellent safety profile and showed dose-dependent central nervous system penetration. Exploratory analyses of plasma Abeta and peak drug levels suggested a short-term effect in plasma that warrants independent verification. The safety, tolerability, and pharmacokinetic profile of R-flurbiprofen in these older individuals support the ongoing studies of this compound in patients with Alzheimer disease.