ABSTRACT
Rational structure-based design has yielded highly potent inhibitors of cathepsin K (Cat K) with excellent physical properties, selectivity profiles, and pharmacokinetics. Compounds with a 3,4-(CH3O)2Ph motif, such as 31, were found to have excellent metabolic stability and absorption profiles. Through metabolite identification studies, a reactive metabolite risk was identified with this motif. Subsequent structure-based design of isoteres culminated in the discovery of an optimized and balanced inhibitor (indazole, 38).
Subject(s)
Cathepsin K/antagonists & inhibitors , Cyclohexanes/chemical synthesis , Indazoles/chemical synthesis , Animals , Blood Proteins/metabolism , Cells, Cultured , Cyclohexanes/pharmacokinetics , Cyclohexanes/pharmacology , Drug Design , Hepatocytes/metabolism , Humans , Indazoles/pharmacokinetics , Indazoles/pharmacology , Male , Models, Molecular , Protein Binding , Rats , Rats, Wistar , Stereoisomerism , Structure-Activity RelationshipABSTRACT
The discovery of nitrile compound 4, a potent inhibitor of Cathepsin K (Cat K) with good bioavailability in dog is described. The compound was used to demonstrate target engagement and inhibition of Cat K in an in vivo dog PD model. The margin to hERG ion channel inhibition was deemed too low for a clinical candidate and an optimisation program to find isosteres or substitutions on benzothiazole group led to the discovery of 20, 24 and 27; all three free from hERG inhibition.
Subject(s)
Benzothiazoles/chemistry , Benzothiazoles/pharmacology , Cathepsin K/antagonists & inhibitors , Ether-A-Go-Go Potassium Channels/antagonists & inhibitors , Nitriles/chemistry , Nitriles/pharmacology , Animals , Benzothiazoles/metabolism , Benzothiazoles/pharmacokinetics , Cathepsin K/metabolism , Dogs , Ether-A-Go-Go Potassium Channels/metabolism , Humans , Microsomes, Liver/metabolism , Models, Molecular , Nitriles/metabolism , Nitriles/pharmacokinetics , Rats , Structure-Activity RelationshipABSTRACT
Directed screening of nitrile compounds revealed 3 as a highly potent cathepsin K inhibitor but with cathepsin S activity and very poor stability to microsomes. Synthesis of compounds with reduced molecular complexity, such as 7, revealed key SAR and demonstrated that baseline physical properties and in vitro stability were in fact excellent for this series. The tricycle carboline P3 unit was discovered by hypothesis-based design using existing structural information. Optimization using small substituents, knowledge from matched molecular pairs, and control of lipophilicity yielded compounds very close to the desired profile, of which 34 (AZD4996) was selected on the basis of pharmacokinetic profile.
Subject(s)
Carbolines/pharmacology , Cathepsin K/antagonists & inhibitors , Indoles/pharmacology , Osteoarthritis/drug therapy , Protease Inhibitors/pharmacology , Animals , Carbolines/metabolism , Carbolines/pharmacokinetics , Carbolines/therapeutic use , Cathepsin K/chemistry , Dogs , Humans , Indoles/metabolism , Indoles/pharmacokinetics , Indoles/therapeutic use , Inhibitory Concentration 50 , Male , Models, Molecular , Osteoarthritis/enzymology , Protease Inhibitors/metabolism , Protease Inhibitors/pharmacokinetics , Protease Inhibitors/therapeutic use , Protein Conformation , Rats , Substrate SpecificityABSTRACT
Allogeneic stem cell transplantation is curative for certain cancers, but the high doses of chemotherapy/radiotherapy lead to toxicity. Here, we treat patients with refractory cancer with 100 cGy total body irradiation (TBI) followed by infusion of nonmobilized pheresed allogeneic peripheral blood cells. Twenty-five patients, with a median age of 47 years, with refractory cancers were enrolled. Eighteen patients received sibling and 7 received unrelated cord blood cells. Donor chimerism was assessed at weeks 1, 2, 3, 4, and 8 after transplantation. Seven patients with solid tumors received a sibling transplant and 6 received a cord blood transplant; none achieved donor chimerism, but 1 treated at the higher dose level of 1 x 10(8) CD3+ cells/kg had a transient nodal response. Twelve patients with hematologic malignancies were treated; 1 received a cord blood transplant and 11 received sibling donor cells. Nine of these 11 patients achieved donor chimerism, ranging from 5% to 100%. Four patients had sustained complete remission of their cancers, including one patient with transient 5% donor chimerism. The development of chimerism correlated with hematologic malignancy (P <.001), total previous myelotoxic chemotherapy (P <.001), T-cell dose (P =.03), and graft-versus-host disease (P =.01). Tumor response correlated with donor chimerism (P =.01). Engraftment was achieved in patients with hematologic malignancies who had been heavily pretreated, suggesting the degree of immunosuppression may be a determinant of engraftment. Low-dose TBI and allogeneic lymphocyte infusion may induce remission in patients with refractory hematologic malignancy.
