Modeling and simulation of the endogenous CYP3A induction marker 4β-hydroxycholesterol during enasidenib treatment

Yan Li,1 Jamie N Connarn,1 Jian Chen,2 Zeen Tong,2 Maria Palmisano,1 Simon Zhou1 1Translational Development and Clinical Pharmacology, Celgene Corporation, Summit, NJ, USA; 2Non-Clinical Development, Celgene Corporation, Summit, NJ, USA Background: Enasidenib (IDHIFA®, AG-221) is a first-in-class, targeted inhibitor of mutant IDH2 proteins for treatment of relapsed or refractory acute myeloid leukemia. This was a Phase I/II study evaluating safety, efficacy, and pharmacokinetics/pharmacodynamics (PK/PD) of orally administered enasidenib in subjects with advanced hematologic malignancies with an IDH2 mutation. Methods: Blood samples for PK and PD assessment were collected. A semi-mechanistic non-linear mixed effect PK/PD model was successfully developed to characterize enasidenib plasma PK and to assess enasidenib-induced CYP3A activity. Results: The PK model showed that enasidenib plasma concentrations were adequately described by a one-compartment model with first-order absorption and elimination; the PD model showed a high capacity to induce CYP3A (Emax=7.36) and a high enasidenib plasma concentration to produce half of maximum CYP3A induction (EC50 =31,400 ng/mL). Monte Carlo simulations based on the final PK/PD model showed that at 100 mg once daily dose there was significant drug accumulation and a maximum of three-fold CYP3A induction after multiple doses. Although the EC50 value for CYP3A induction by enasidenib is high, CYP3A induction was observed due to significant drug accumulation. Conclusion: CYP3A induction following enasidenib dosing should be considered when prescribing concomitant medication metabolized via this pathway. Keywords: enasidenib, modeling and simulation, CYP3A induction, 4β-hydroxycholestero

Backbone and methyl resonance assignments of the 42 kDa human Hsc70 nucleotide binding domain in the ADP state

Hsc70 is the constitutively expressed mammalian heat shock 70 kDa (Hsp70) cytosolic chaperone. It plays a central role in cellular proteostasis and protein trafficking. Here, we present the backbone and methyl group assignments for the 386-residue nucleotide binding domain of the human protein. This domain controls the chaperone’s allostery, binds multiple co-chaperones and is the target of several classes of known chemical Hsp70 inhibitors. The NMR assignments are based on common triple resonance experiments with triple labeled protein, and on several (15)N and (13)C-resolved 3D NOE experiments with methyl-reprotonated samples. A combination of computer and manual data interpretation was used

The remarkable multivalency of the Hsp70 chaperones

Hsp70 proteins are key to maintaining intracellular protein homeostasis. To carry out this task, they employ a large number of cochaperones and adapter proteins. Here, we review what is known about the interaction between the chaperones and partners, with a strong slant toward structural biology. Hsp70s in general, and Hsc70 (HSPA8) in particular, display an amazing array of interfaces with their protein cofactors. We also review the known interactions between Hsp70s with lipids and with active compounds that may become leads toward Hsp70 modulation for treatment of a variety of diseases