Evaluation of selective gamma-secretase inhibitor PF-03084014 for its antitumor efficacy and gastrointestinal safety to guide optimal clinical trial design.
Aberrant regulation of Notch signaling has been implicated in tumorigenesis. Proteolytic release of the Notch intracellular domain (NICD) by gamma-secretase plays a key role in Notch-dependent nuclear signaling. gamma-Secretase is an attractive pharmaceutical target for therapeutic intervention in cancer. We describe the potent antitumor effects of PF-03084014, a small molecule that is a reversible, noncompetitive, and selective gamma-secretase inhibitor. The ability of PF-03084014 to inhibit gamma-secretase activity was shown by the reduction of endogenous NICD levels and by the downregulation of Notch target genes Hes-1 and cMyc in the T-cell acute lymphoblastic leukemia (T-ALL) cell line HPB-ALL. PF-03084014 caused cell growth inhibition of several T-ALL cell lines via cell cycle arrest and induction of apoptosis. PF-03084014 treatment also resulted in robust NICD reduction in HBP-ALL xenograft models. Broad antitumor efficacy at well-tolerated dose levels was observed in six Notch-dependent models. Additional mechanism-of-action studies showed inhibition of tumor cell proliferation and induction of apoptosis in HPB-ALL tumors, suggesting that the antitumor activity of PF-03084014 may be mediated by its direct effects on tumor cell growth or survival. Further studies on PF-03084014-induced gastrointestinal toxicity identified an intermittent dosing schedule that displayed reduced body weight loss and sustained antitumor efficacy. We also showed that glucocorticoids abrogated PF-03084014-induced gastrointestinal toxicity and delayed administration of glucocorticoids did not compromise its protection effect. Collectively, the results show that inhibition of Notch signaling by PF-03084014 while minimizing gastrointestinal toxicity presents a promising approach for development of therapies for Notch receptor-dependent cancers. This compound is being investigated for the treatment of T-ALL and advanced solid tumors in phase I clinical trials.
Drug Discovery Group and Oncology Research Unit, Pfizer Global Research and Development, La Jolla Laboratories, San Diego, California 92121, USA.
Ping
P
Wei
Marlena
M
Walls
Ming
M
Qiu
Richard
R
Ding
Robert H
RH
Denlinger
Anthony
A
Wong
Kosta
K
Tsaparikos
Jitesh P
JP
Jani
Natilie
N
Hosea
Michelle
M
Sands
Sophia
S
Randolph
Tod
T
Smeal
D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002986:Clinical Trials as Topic / Q000592:standards; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D041981:Gastrointestinal Tract / Q000187:drug effects* / Q000473:pathology; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D006801:Humans; D011480:Protease Inhibitors / Q000008:administration & dosage / Q000494:pharmacology* / Q000633:toxicity; D017434:Protein Structure, Tertiary; D051880:Receptors, Notch / Q000737:chemistry / Q000378:metabolism; D013764:Tetrahydronaphthalenes / Q000008:administration & dosage / Q000009:adverse effects* / Q000494:pharmacology*; D013997:Time Factors; D016896:Treatment Outcome; D014633:Valine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D011480:Protease Inhibitors; D051880:Receptors, Notch; D013764:Tetrahydronaphthalenes; D003907:Dexamethasone; D053829:Amyloid Precursor Protein Secretases; D014633:Valine; C550722:nirogacestat