The in vitro and in vivo pharmacological properties of N-(4-fluorophenylmethyl)-N-(1-methylpiperidin-4-yl)-NЈ-(4-( (Snyder, 1976;Carlsson et al., 1999a). Unfortunately, antagonism of D 2 receptors also causes profound motor, endocrine, and cognitive side effects, which can 1 Current affiliation: TorreyPines Therapeutics,

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B7-H3, also referred to as CD276, is a member of the B7 family of immune regulatory proteins. B7-H3 is overexpressed on many solid cancers, including prostate cancer, renal cell carcinoma, melanoma, squamous cell carcinoma of the head and neck, non-small cell lung cancer and breast cancer. Over-expression of B7-H3 is associated with disease severity, risk of recurrence and reduced survival. In this article, we report the preclinical development of MGC018, an antibodydrug conjugate targeted against B7-H3. MGC018 is comprised of the cleavable linkerduocarmycin payload, valine-citrulline-seco duocarmycin hydroxybenzamide azaindole (vcseco-DUBA), conjugated to an anti-B7-H3 humanized IgG1/kappa monoclonal antibody through reduced interchain disulfides, with an average drug-to-antibody ratio of ~2.7. MGC018 exhibited cytotoxicity toward B7-H3-positive human tumor cell lines, and exhibited bystander killing of target-negative tumor cells when co-cultured with B7-H3-positive tumor cells. MGC018 displayed potent antitumor activity in preclinical tumor models of breast, ovarian and lung cancer, as well as melanoma. Additionally, antitumor activity was observed toward patientderived xenograft models of breast, prostate and head and neck cancer displaying heterogeneous expression of B7-H3. Importantly, MGC018 exhibited a favorable pharmacokinetic and safety profile in cynomolgus monkeys following repeat-dose administration. The antitumor activity observed preclinically with MGC018, together with the positive safety profile, provides evidence of a potentially favorable therapeutic index and supports the continued development of MGC018 for the treatment of solid cancers.

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The primary purpose of the present series of experiments was to characterize the in vitro and in vivo pharmacology profile of 2-(4-methoxy-phenyl)-N-(4-methyl-benzyl)-N-(1-methyl-piperidin-4-yl)-acetamide hydrochloride (AC-90179), a selective serotonin (5-HT 2A ) receptor inverse agonist, in comparison with the antipsychotics haloperidol and clozapine. The secondary purpose was to characterize the pharmacokinetic profile of AC-90179. Like all atypical antipsychotics, AC-90179 shows high potency as an inverse agonist and competitive antagonist at 5HT 2A receptors. In addition, AC-90179 exhibits antagonism at 5HT 2C receptors. In contrast, AC-90179 does not have significant potency for D 2 and H 1 receptors that have been implicated in the dose-limiting side effects of other antipsychotic drugs. The ability of AC-90179 to block 5-HT 2A receptor signaling in vivo was demonstrated by its blockade of the rate-decreasing effects of the 5-HT 2A agonist, (Ϯ)-2,5-dimethoxy-4-iodoamphetamine hydrochloride, under a fixed ratio schedule of reinforcement. Similar to clozapine and haloperidol, AC-90179 attenuated phencyclidineinduced hyperactivity. Although haloperidol impaired acquisition of a simple autoshaped response and induced cataleptic-like effects at behaviorally efficacious doses, AC-90179 and clozapine did not. Furthermore, unlike haloperidol and clozapine, AC-90179 did not decrease spontaneous locomotor behavior at efficacious doses. Limited oral bioavailability of AC-90179 likely reflects rapid metabolism rather than poor absorption. Taken together, a compound with a similar pharmacological profile as AC-90179 and with increased oral bioavailability may have potential for the treatment of psychosis.