pf-00299804 and Stomach-Neoplasms

Dacomitinib, an irreversible panHER inhibitor, shows significant preclinical antitumor activity in human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC). The aim of this study was to evaluate the clinical activity of dacomitinib and discover potential biomarkers in HER2-positive GC patients.. We enrolled previously treated advanced HER2-positive GC [HER2 FISH (+) or HER2 IHC 3+] patients. The patients received dacomitinib 45 mg once daily.. A total of 27 patients were enrolled. The number of prior chemotherapy regimens was 1 in 7 patients (26 %), 2 in 9 patients (33 %), and more than 2 in 11 patients (41 %). Seven patients had received prior anti-HER2 therapy. The 4-month progression-free survival (PFS) rate was 22.2 % and median PFS was 2.1 months (95 % CI, 2.3-3.4) There were 2 partial response (PRs) and 9 stable disease (SDs), resulting in 7.4 % (95 % CI, 0-17.5 %) of response rate (RR) and 40.7 % (95 % CI, 21.9-59.6 %) of disease control rate (DCR). Eleven patients (41 %) showed some degree of tumor shrinkage. Overall survival was 7.1 months (95 % CI, 4.4-9.8). The most common toxicities were skin rash, diarrhea, and fatigue, most of which were grade 1 or 2. The Ctrough of dacomitinib was lower in gastrectomy patients than nongastrectomy patients. Higher serum levels of HER2 extracellular domain (ECD) and lower levels of soluble E-cadherin (sECAD) correlated with higher dacomitinib activity.. Dacomitinib functions as a single agent in HER2-positive GC patients with a tolerable safety profile. HER2 ECD and sECAD have the potential to be biomarkers for patient selection in a panHER inhibition strategy for HER2-positive GC. (ClinicalTrials.gov: NCT01152853).

Topics: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Female; Follow-Up Studies; Humans; Immunoenzyme Techniques; Male; Middle Aged; Neoplasm Invasiveness; Neoplasm Staging; Prognosis; Quinazolinones; Receptor, ErbB-2; Stomach Neoplasms; Survival Rate; Tissue Distribution

Recently, HER2-directed treatment, such as trastuzumab, has shown clinical benefit in HER2-amplified gastric cancer. On the basis of recent studies about epidermal growth factor receptor (EGFR) or HER2-targeting agents (including gefitinib, lapatinib, and trastuzumab) in gastric cancer, the potent effects of pan-HER inhibitors targeting the HER family are anticipated. In this study, we evaluated the activity and mechanisms of PF00299804, an irreversible pan-HER inhibitor, in gastric cancer in vitro and in vivo models. PF00299804 showed significant growth-inhibitory effects in HER2-amplified gastric cancer cells (SNU216, N87), and it had lower 50% inhibitory concentration values compared with other EGFR tyrosine kinase inhibitors, including gefitinib, lapatinib, BIBW-2992, and CI-1033. PF00299804 induced apoptosis and G(1) arrest and inhibited phosphorylation of receptors in the HER family and downstream signaling pathways including STAT3, AKT, and extracellular signal-regulated kinases (ERK) in HER2-amplified gastric cancer cells. PF00299804 also blocked EGFR/HER2, HER2/HER3, and HER3/HER4 heterodimer formation as well as the association of HER3 with p85α in SNU216 cells. The combination of PF00299804 with clinically relevant chemotherapeutic agents or molecular-targeted agents including trastuzumab (an anti-HER2 monoclonal antibody), CP751871 (an IGF1R inhibitor), PD0325901 (an ERK1/2 inhibitor), and PF04691502 (a PI3K/mTOR inhibitor) produced synergistic effects. These findings indicate that PF00299804 can be used as a targeted therapy for the treatment of HER2-amplified gastric cancer through inhibition of HER family heterodimer formation and may augment antitumor efficacy of chemotherapeutic and/or molecular-targeted agents.

Topics: Animals; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Blotting, Western; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Drug Synergism; Female; G1 Phase; Humans; Mice; Mice, SCID; Molecular Structure; Protein Kinase Inhibitors; Quinazolinones; Receptor, ErbB-2; Stomach Neoplasms; Time Factors; Trastuzumab; Tumor Burden; Xenograft Model Antitumor Assays