Mark J. Ratain
Mark J. Ratain, MD

Leon O. Jacobson Professor of Medicine, director, Center for Personalized Therapeutics, associate director for clinical sciences, The University of Chicago Comprehensive Cancer Center; The Value in Cancer Care Consortium

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FreeGuest Editorial
This story is part of The Cancer Letter's ongoing coverage of COVID-19's impact on oncology. A full list of our coverage, as well as the latest meeting cancellations, is available here.
ClinicalFreeTrials & Tribulations
Historically, oncology drug development has evolved on what may seem to be a different planet, at least relative to mainstream clinical pharmacology.
ClinicalFreeTrials & Tribulations
Ibrutinib is a selective and irreversible inhibitor of Bruton's tyrosine kinase (BTK) that entered phase 1 clinical trials in 2009 based on preclinical efficacy in models of B-cell malignancy and autoimmune disease.[1, 2] The initial phase 1 trial showed clear efficacy in a number of lymphoid malignancies at doses as low as 1.25 mg/kg/d. Furthermore, full receptor occupancy was demonstrated at 2.5 mg/kg/d. Despite these pharmacological and early clinical findings, development of ibrutinib continued at doses of 420 mg qd and 560 mg qd, levels 3-4 fold higher than suggested by the pharmacological data. In addition, the absorption of ibrutinib is enhanced by administration of food, which may explain why even the lowest dose showed efficacy in some patients.