5-(4-amino-1-propan-2-yl-3-pyrazolo[3-4-d]pyrimidinyl)-1-3-benzoxazol-2-amine and palbociclib

Hepatocellular carcinoma (HCC) is the sixth most common primary cancer with an unsatisfactory long-term survival. Gain of function mutations of PIK3CA occur in a subset of human HCC. Alpelisib, a selective PIK3CA inhibitor, has been approved by the FDA to treat PIK3CA mutant breast cancers. In this manuscript, we evaluated the therapeutic efficacy of alpelisib, either alone or in combination, for the treatment of HCC. We tested alpelisib in mouse HCC induced by hydrodynamic injection of c-Met/PIK3CA(H1047R) (c-Met/H1047R), c-Met/PIK3CA(E545K) (c-Met/E545K), and c-Met/sgPten gene combinations. Alpelisib slowed down the growth of c-Met/H1047R and c-Met/E545K HCC but was ineffective in c-Met/sgPten HCC. Mechanistically, alpelisib inhibited p-ERK and p-AKT in c-Met/H1047R and c-Met/E545K HCC progression but did not affect the mTOR pathway or genes involved in cell proliferation. In human HCC cell lines transfected with PIK3CA(H1047R), alpelisib synergized with the mTOR inhibitor MLN0128 or the CDK4/6 inhibitor palbociclib to suppress HCC cell growth. In c-Met/H1047R mice, alpelisib/MLN0128 or alpelisib/palbociclib combination therapy caused tumor regression. Our study demonstrates that alpelisib is effective for treating PIK3CA-mutated HCC by inhibiting MAPK and AKT cascades. Furthermore, combining alpelisib with mTOR or CDK4/6 inhibitors has a synergistic efficacy against PIK3CA-mutated HCC, providing novel opportunities for precision medicine against HCC.

Topics: Anilides; Animals; Benzoxazoles; Carcinogenesis; Carcinoma, Hepatocellular; Cell Line, Tumor; Class I Phosphatidylinositol 3-Kinases; Disease Models, Animal; Female; Humans; Liver Neoplasms; MAP Kinase Signaling System; Mice; Molecular Targeted Therapy; Mutation; Piperazines; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-met; PTEN Phosphohydrolase; Pyridines; Pyrimidines; Thiazoles; Treatment Outcome; Tumor Burden

Intrahepatic cholangiocarcinoma (ICC) is an aggressive cancer type, lacking effective therapies and associated with a dismal prognosis. Palbociclib is a selective CDK4/6 inhibitor, which has been shown to suppress cell proliferation in many experimental cancer models. Recently, we demonstrated that pan-mTOR inhibitors, such as MLN0128, effectively induce apoptosis, although have limited efficacy in restraining proliferation of ICC cells. Here, we tested the hypothesis that palbociclib, due to its antproliferative properties in many cancer types, might synergize with MLN0128 to impair ICC growth.. Human ICC cell lines and the AKT/YapS127A ICC mouse model were used to test the therapeutic efficacy of palbociclib and MLN0128, either alone or in combination.. Our study indicates the synergistic activity of palbociclib and MLN0128 in inhibiting ICC cell proliferation. Thus, combination of CDK4/6 and mTOR inhibitors might represent a novel, promising, and effective therapeutic approach against human ICC.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzoxazoles; Cell Line, Tumor; Cell Proliferation; Cholangiocarcinoma; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase 6; Heterografts; Humans; Mice; Phosphorylation; Piperazines; Protein Kinase Inhibitors; Pyridines; Pyrimidines; TOR Serine-Threonine Kinases

Palbociclib is an approved cyclin-dependent kinase (CDK) 4/6 inhibitor for treatment of patients with ER-positive and HER2-negative breast cancers. While Retinoblastoma protein (pRb), a major substrate of CDK4/6, is a potential target in triple negative breast cancer (TNBC), the usefulness of CDK4/6 inhibitors in this cancer has not been established. This preclinical study investigated the combination effects of palbociclib and the dual mammalian target of rapamycin (mTOR) kinase inhibitor MLN0128 in estrogen receptor (ER)-negative breast cancer in vitro and in vivo.. The combined effects of two drugs on three TNBC cell lines (MB231, MB468, and CAL148) and an ER-negative and HER2-positive cell line (MB453) were investigated by MTT assay and colony formation analysis. Cell cycle measurements were examined as well as changes in expression of molecules related to G1/S transition and the mTOR pathway. Importantly, a pRb-expressing TNBC patient-derived xenograft (PDX) model was used to assess the effects of the combination in vivo.. A combination of palbociclib and MLN0128 synergistically inhibited the proliferation of pRb-expressing cell lines and induced G1 cell cycle arrest. Western blot analysis revealed that CDK4/6-pRb and mTOR pathways were inhibited by these treatments. In pRb-expressing TNBC PDX, the combination treatment drastically suppressed tumor growth compared to either the control or single drug treatments. In addition, the combination treatment significantly reduced the number of Ki67-positive cells.. We revealed that palbociclib and MLN0128 had synergistic anti-cancer activity in both pRb + ER-negative cell lines and a TNBC PDX model. Our results indicate that such combination therapy is worthy of further investigation in a clinical setting.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Benzoxazoles; Breast Neoplasms; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Synergism; Female; Humans; Mice; Piperazines; Protein Kinase Inhibitors; Pyridines; Pyrimidines; Receptors, Estrogen; Retinoblastoma Protein; Xenograft Model Antitumor Assays