突变体
乳腺癌
磷脂酰肌醇
雌激素受体α
雌激素受体
阿尔法(金融)
激酶
癌症
癌症研究
医学
生物
内科学
肿瘤科
遗传学
基因
结构效度
护理部
患者满意度
作者
Wei Yang,Sarah R. Hosford,Lloye M. Dillon,Kevin Shee,Stephanie C. Liu,Jennifer R. Bean,Laurent Salphati,Jodie Pang,Xiaolin Zhang,Michelle Nannini,Eugene Demidenko,Darcy Bates,Lionel D. Lewis,Jonathan D. Marotti,Alan Eastman,Todd W. Miller
标识
DOI:10.1158/1078-0432.ccr-15-2276
摘要
Abstract Purpose: Phosphatidylinositol 3-kinase (PI3K) inhibitors are being developed for the treatment of estrogen receptor α (ER)–positive breast cancer in combination with antiestrogens. Understanding the temporal response and pharmacodynamic effects of PI3K inhibition in ER+ breast cancer will provide a rationale for treatment scheduling to maximize therapeutic index. Experimental Design: Antiestrogen-sensitive and antiestrogen-resistant ER+ human breast cancer cell lines and mice bearing PIK3CA-mutant xenografts were treated with the antiestrogen fulvestrant, the PI3K inhibitor GDC-0941 (pictilisib; varied doses/schedules that provided similar amounts of drug each week), or combinations. Cell viability, signaling pathway inhibition, proliferation, apoptosis, tumor volume, and GDC-0941 concentrations in plasma and tumors were temporally measured. Results: Treatment with the combination of fulvestrant and GDC-0941, regardless of dose/schedule, was significantly more effective than that with single-agent treatments in fulvestrant-resistant tumors. Short-term, complete PI3K inhibition blocked cell growth in vitro more effectively than chronic, incomplete inhibition. Longer-term PI3K inhibition hypersensitized cells to growth factor signaling upon drug withdrawal. Different schedules of GDC-0941 elicited similar tumor responses. While weekly high-dose GDC-0941 with fulvestrant continuously suppressed PI3K signaling for 72 hours, inducing a bolus of apoptosis and inhibiting proliferation, PI3K reactivation upon GDC-0941 washout induced a proliferative burst. Fulvestrant with daily low-dose GDC-0941 metronomically suppressed PI3K for 6 to 9 hours/day, repeatedly inducing small amounts of apoptosis and temporarily inhibiting proliferation, followed by proliferative rebound compared with fulvestrant alone. Conclusions: Continuous and metronomic PI3K inhibition elicits robust anticancer effects in ER+, PIK3CA-mutant breast cancer. Clinical exploration of alternate treatment schedules of PI3K inhibitors with antiestrogens is warranted. Clin Cancer Res; 22(9); 2250–60. ©2016 AACR. See related commentary by Toska and Baselga, p. 2099
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