It was demonstrated that in vitro flux measurements using lipophilic artificial membranes could correctly reproduce the rank order of PK results for ITZ formulations. The drop in flux over time for solid dispersions could be backed by experimental indications of crystallization.

The high number of poorly water-soluble compounds in drug development has increased the need for enabling formulations to improve oral bioavailability. One frequently applied approach is to induce supersaturation at the absorptive site, e.g., the small intestine, increasing the amount of dissolved compound available for absorption. However, due to the stochastic nature of nucleation, supersaturating drug delivery systems may lead to inter- and intrapersonal variability. The ability to define a feasible range with respect to the supersaturation level is a crucial factor for a successful formulation. Therefore, an in vitro method is needed, from where the ability of a compound to supersaturate can be defined in a reproducible way. Hence, this study investigates the reproducibility of an in vitro small scale standardized supersaturation and precipitation method (SSPM). First an intralaboratory reproducibility study of felodipine was conducted, after which seven partners contributed with data for three model compounds; aprepitant, felodipine, and fenofibrate, to determine the interlaboratory reproducibility of the SSPM. The first part of the SSPM determines the apparent degrees of supersaturation (aDS) to investigate for each compound. Each partner independently determined the maximum possible aDS and induced 100, 87.5, 75, and 50% of their determined maximum possible aDS in the SSPM. The concentration-time profile of the supersaturation and following precipitation was obtained in order to determine the induction time (t) for detectable precipitation. The data showed that the absolute values of t and aDS were not directly comparable between partners, however, upon linearization of the data a reproducible rank ordering of the three model compounds was obtained based on the β-value, which was defined as the slope of the ln(t) versus ln(aDS) plot. Linear regression of this plot showed that aprepitant had the highest β-value, 15.1, while felodipine and fenofibrate had comparable β-values, 4.0 and 4.3, respectively. Of the five partners contributing with full data sets, 80% could obtain the same rank order for the three model compounds using the SSPM (aprepitant > felodipine ≈ fenofibrate). The α-value is dependent on the experimental setup and can be used as a parameter to evaluate the uniformity of the data set. This study indicated that the SSPM was able to obtain the same rank order of the β-value between partners and, thus, that the SSPM may be used to classify compounds depending on their supersaturation propensity.

The BCL6 transcription repressor (B-cell lymphoma 6, BCL6) protein has been shown to be a key molecular driver of diffuse large B-cell lymphoma (DLBCL). Somatic mutations of the BCL6 gene include gross- or cryptic-chromosome translocations and point mutations that have been shown to result in the deregulation of BCL6 expression. These BCL6 abnormalities also contribute to a subgroup of high-risk (HR) aggressive double- and triple-hit (DH/TH) lymphomas with very poor outcomes. We have developed highly specific, potent and orally bioavailable BCL6 PROteolysis TArgeting Chimera (PROTAC TM) degraders that demonstrate potent in-vitro and in-vivo efficacy in multiple pre-clinical DLBCL models. Ten of 12 germinal center B-cell (GCB) and two of four activated B-cell (ABC) DLBCL cell lines show significant growth inhibition in-vitro with BCL6 PROTAC TM treatment, demonstrating a critical dependence on BCL6. This array of sensitivity across genetically variable cell lines suggests that BCL6-dependence is not just associated with BCL6-mutated DLBCLs. A more advanced BCL6 PROTAC TM, ARVN-71228, achieves >95% BCL6 D max in-vitro at a DC 50 of <1 nM in the OCI-Ly1 model following 24 hr treatment, degrading BCL6 equally well in the nuclear, chromatin-bound and cytosolic cell fractions. BCL6 degradation is associated with dose-dependent G1 cell cycle arrest and elevated apoptosis that increases over time (24 vs 72 hours). In head-to-head BCL6 degradation and growth inhibition studies using OCI-Ly1, the ARVN-71228 BCL6 PROTAC TM demonstrates superior activity compared to recently published BCL6-targeted degraders/inhibitors and heterobifunctional molecules. Importantly, medicinal chemistry efforts have resulted in the successful development of orally bioavailable BCL6 PROTAC TM degraders for in-vivo dosing. Time-course studies show >95% BCL6 loss within four hours which is maintained at 8-, 16- and 24-hours. Genes repressed by BCL6 such as BLIMP1 and PTPN6 are derepressed and show increased protein levels 24 hours post-dose. ARVN-71228 achieves regressions in the GCB OCI-Ly1 CDX model. Future studies plan to look at rational drug combinations with BCL6 PROTAC TM degraders to find collaborative or synergistic pathways to target, especially in the HR-DLBCL subtypes where there is a high unmet medical need. Disclosures Gough: Arvinas: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Sherman: Arvinas: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. DeCarr: Arvinas: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Eaton: Arvinas: Current Employment, Current equity holder in publicly-traded company. Milanovic: Arvinas: Current Employment, Current equity holder in publicly-traded company. Bookbinder: Arvinas: Current Employment, Current equity holder in publicly-traded company. Pizzano: Arvinas: Current Employment, Current equity holder in publicly-traded company. Altieri: Arvinas: Current Employment, Current equity holder in publicly-traded company. Corradi: Arvinas: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Xiao: Arvinas: Current Employment, Current equity holder in publicly-traded company. Gallego: Arvinas: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Soto: Arvinas: Current Employment, Current equity holder in publicly-traded company. Lingamaneni: Arvinas: Current Employment, Current equity holder in publicly-traded company. Chen: Arvinas: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Zhang: Arvinas: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Wang: Arvinas: Current Employment, Current equity holder in publicly-traded company. Dong: Arvinas: Current Employment, Current equity holder in publicly-traded company. Chirnomas: Arvinas: Current Employment, Current equity holder in publicly-traded company. Berlin: Arvinas: Current Employment, Current equity holder in publicly-traded company. Hornberger: Arvinas: Current Employment, Current equity holder in publicly-traded company. Snyder: Arvinas: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Taylor: Arvinas: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months.