CI994 (Tacedinaline)是一种抗癌药，抑制HDAC1，IC50为0.57 μM，使细胞周期停滞在G1期。Phase 3。CI-994 (< 160 mM) shows cytostatic effect with concomitant increase at G0/G1 phase, a reduction at S phase level and increased apoptosis in A-549 and LX-1 cells. CI-994 inhibits growth of LNCaP cell with IC50 of 7.4 μM. CI-994 exerts activity against several tumor cell lines with greater cytotoxicity against the solid tumors relative to both the leukemia and normal fibroblast cell lines. CI-994 inhibits growth of rat leukemia BCLO cells with IC50 of 2.5 μM.CI-994 exerts demonstrated antitumor activity against several tumor models, including the chemo-resistant mouse pancreatic ductal carcinoma as well as the human prostate tumor model LNCaP.Tacedinaline (CI994, PD-123654, GOE-5549, Acetyldinaline) 是一种选择性的I型HDAC抑制剂，其对HDAC 1, 2, 3,和8的IC50分别为0.9, 0.9, 1.2, 和 >20 μM。Phase 3。

Target	Value
HDAC1 (Cell-free assay)	0.9 μM
HDAC2 (Cell-free assay)	0.9 μM
HDAC3 (Cell-free assay)	1.2 μM

A-549和LX-1细胞中，CI-994(< 160 mM)表现出抑制细胞生长的作用，伴随G0/G1期增加，S期减少，且细胞凋亡增加。 CI-994抑制LNCaP细胞的生长，IC50为7.4 μM。 CI-994对几种肿瘤细胞系具有活性，相对于白血病和正常成纤维细胞系，对固体肿瘤具有更高的细胞毒性。 CI-994抑制大鼠白血病BCLO细胞的生长，IC50为2.5 μM。

CI-994对几种肿瘤模型，包括耐化疗的胰腺导管癌小鼠，和人前列腺肿瘤模型LNCaP，具有已证实的抗肿瘤活性。