FDA Approval Summary: Asciminib for Ph+ CML in Chronic Phase Treated with Two or More Tyrosine Kinase Inhibitors and for the T315I Mutation.

On October 29, 2021, FDA granted accelerated approval to asciminib (Scemblix; Novartis), a tyrosine kinase inhibitor (TKI), for the treatment of adult patients with Philadelphia chromosome positive chronic myeloid leukemia (Ph+ CML) in chronic phase (CP), previously treated with two or more TKIs, and granted traditional approval to asciminib for adult patients with Ph+ CML in CP with the T315I mutation. The first indication was approved based on major molecular response (MMR) at 24 weeks in the ASCEMBL Study, a randomized trial comparing asciminib with bosutinib in patients who had failed two or more TKIs. This indication was ultimately granted traditional approval on October 12, 2022, based on safety data and MMR rate at 96 weeks of 38% (95% CI: 30, 46) in the asciminib arm vs. 16% (95% CI: 8, 26) in the bosutinib arm (p-value: 0.001). The second indication was approved based on MMR rate by 96 weeks of 49% (95% CI: 34, 64) in the single-arm CABL001X2101 Study. The most common (≥20%) adverse reactions included upper respiratory tract infections, musculoskeletal pain, headache, fatigue, nausea, rash, and diarrhea. The most common (≥20%) laboratory abnormalities were thrombocytopenia, neutropenia, anemia, lymphopenia, hypertriglyceridemia, hyperuricemia, increases in creatine kinase, ALT, AST, lipase, and amylase. This manuscript describes the basis for approval of these indications.

Noteworthy idiosyncrasies of 1α,25-dihydroxyvitamin D3 kinetics for extrapolation from mouse to man: Commentary.

Calcitriol or 1,25-dihydroxyvitamin D3 [1,25(OH)2 D3 ] is the active ligand of the vitamin D receptor (VDR) that plays a vital role in health and disease. Vitamin D is converted to the relatively inactive metabolite, 25-hydroxyvitamin D3 [25(OH)D3 ], by CYP27A1 and CYP2R1 in the liver, then to 1,25(OH)2 D3 by a specific, mitochondrial enzyme, CYP27B1 (1α-hydroxylase) that is present primarily in the kidney. The degradation of both metabolites is mostly carried out by the more ubiquitous mitochondrial enzyme, CYP24A1. Despite the fact that calcitriol inhibits its formation and degradation, allometric scaling revealed strong interspecies correlation of the net calcitriol clearance (CL estimated from dose/AUC∞ ), production rate (PR), and basal, plasma calcitriol concentration with body weight (BW). PBPK-PD (physiologically based pharmacokinetic-pharmacodynamic) modeling confirmed the dynamic interactions between calcitriol and Cyp27b1/Cyp24a1 on the decrease in the PR and increase in CL in mice. Close scrutiny of the literature revealed that basal levels of calcitriol had not been taken into consideration for estimating the correct AUC∞ and CL after exogenous calcitriol dosing in both animals and humans, leading to an overestimation of AUC∞ and underestimation of the plasma CL. In humans, CL was decreased in chronic kidney disease but increased in cancer. Collectively, careful pharmacokinetic data analysis and improved definition are achieved with PBPK-PD modeling, which embellishes the complexity of dose, enzyme regulation, and disease conditions. Allometric scaling and PBPK-PD modeling were applied successfully to extend the PBPK model to predict calcitriol kinetics in cancer patients.

FDA's Approval of the First Biosimilar to Bevacizumab.

Passage of the Biologics Price Competition and Innovation Act of 2009 created an abbreviated licensure pathway for biosimilar products. The FDA approved ABP215 (MVASI, bevacizumab-awwb; Amgen) as a biosimilar to U.S.-licensed Avastin (bevacizumab; Genentech) based on an extensive comparative analytic characterization, data obtained in a pharmacokinetic similarity study in healthy subjects, and a comparative clinical study in patients with non-small cell lung cancer. The totality of the evidence for biosimilarity supported extrapolation of the data to support licensure as a biosimilar for other approved indications of U.S.-licensed Avastin, without the need of additional clinical studies. Clin Cancer Res; 24(18); 4365-70. ©2018 AACR.

Beta-catenin signaling pathway is crucial for bone morphogenetic protein 2 to induce new bone formation.

Endochondral ossification is recapitulated during bone morphogenetic protein (BMP)-induced ectopic bone formation. Although BMP and beta-catenin have been investigated in bone development and in mesenchymal cells, how they interact in this process is not clear. We implanted recombinant BMP-2 into the muscle of mice to investigate the effect of beta-catenin signaling on BMP-induced in vivo endochondral bone formation. BMP-2 induced expression of several Wnt ligands and their receptors and also activated beta-catenin-mediated T cell factor-dependent transcriptional activity. An adenovirus expressing Dickkopf-1 (Dkk-1, an inhibitor of canonical Wnt pathway) inhibited beta-catenin signaling and endochondral bone formation. Interestingly, Dkk-1 inhibited both chondrogenesis and osteogenesis. Likewise, mice expressing conditional beta-catenin null alleles also displayed an inhibition of BMP-induced chondrogenesis and osteogenesis. This is in contrast to studies of embryonic skeletogenesis, which demonstrate that beta-catenin is required for osteogenesis but is dispensable for chondrogenesis. These findings suggest that embryonic development pathways are not always recapitulated during post-natal regenerative processes, and the biochemical pathways utilized to regulate cell differentiation may be different. During in vivo ectopic bone formation, BMP-2 induces beta-catenin-mediated signaling through Wnt ligands, and beta-catenin is required for both chondrogenesis and osteogenesis.