Characterization and phase I study of CLR457, an orally bioavailable pan-class I PI3-kinase inhibitor

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Institut Català de la Salut

[Harding JJ] Memorial Sloan Kettering Cancer Center, New York, NY, USA. [Bauer TM] Sarah Cannon Research Institute / Tennessee Oncology, PLLC, Nashville, TN, USA. [Tan DSW] National Cancer Centre, Singapore, Singapore. [Bedard PL] Princess Margaret Cancer Centre, Toronto, ON, Canada. [Rodon J] Vall d’Hebron Hospital Universitari, Barcelona, Spain. [Doi T] National Cancer Center East, Kashiwa, Chiba, Japan

Vall d'Hebron Barcelona Hospital Campus

Publication date

2021-04-16T14:24:14Z

2021-04-16T14:24:14Z

2018

2019-04-15



Abstract

CLR457; Inhibidor Pan-PI3K; Fase I


CLR457; Inhibidor Pan-PI3K; Fase I


CLR457; Pan-PI3K inhibitor; Phase I


Background CLR457 is an orally bioavailable pan-phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) inhibitor. Methods CLR457 anti-tumor activity and pharmacokinetics (PK) were characterized by in vitro biochemical assays and in vivo tumor xenografts. A first-in-human study was conducted to determine the maximum tolerated dose (MTD), safety, PK, and efficacy of CLR457. Successive cohorts of patients with advanced solid tumors with PI3K pathway activation received increasing CLR457 doses according to a Bayesian escalation model based on the rate of dose limiting toxicity (DLT) in the first 28-day cycle. Results CLR457 inhibited p110α, p110β, p110δ and p110γ isoforms with an IC50 of 89 ± 29 nM, 56 ± 35 nM, 39 ± 10 nM and 230 ± 31 nM, respectively. CLR457 exhibited dose-dependent antitumor activity and interfered with glucose homeostasis in PI3K-mutant tumor xenografts. 31 patients received doses ranging from 5 to 100 mg. DLTs included grade 3 hyperglycemia and rash (3). In the 100 mg cohort (n = 11), 3 (27.3%) patients had DLTs and all patients (100%) experienced ≥ grade 3 toxicity with rash (45.5%) as the most common event. The MTD was not determined. For the entire study population, stomatitis (45.2%), diarrhea (38.7%), rash (35.5%) were the most common any grade toxicities—51.6% patients experienced ≥ Grade 3 toxicity. CLR457 was rapidly absorbed with limited accumulation and linear PK. PK modeling indicated that pharmacologically active concentrations were achieved at the highest dose tested (100 mg), though no objective responses were observed. Conclusion CLR457 clinical development was terminated due to poor tolerability and limited antitumor activity. These results emphasize the difficulty of achieving a wide therapeutic index when targeting all class I PI3K-isoforms.


Novartis Pharmaceuticals Corporation.

Document Type

Article


Published version

Language

English

Publisher

Springer

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Attribution 4.0 International

http://creativecommons.org/licenses/by/4.0/

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