poziotinib and Neoplasm-Metastasis

We aimed to investigate the impact of genetic alterations on the efficacy of poziotinib in a phase II clinical trial of patients with heavily treated HER2-positive metastatic breast cancer (BC). We performed targeted ultra-deep sequencing with a customized cancer gene panel and RNA expression assay using BC specimens. Of 106 patients, biomarker data were available for 85. Copy number (CN) amplifications of HER2 were observed in 72 patients (85%), and CN >8 in 50 (59%). Single nucleotide variants (SNVs) of HER2 were found in 16 patients (19%). Genetic alterations of PIK3CA pathway were found in 40 patients (47%). Median progression free survival (PFS) of the biomarker analysis group was 3.61 months. In terms of PFS, HER2 with CN >8 prolonged (hazard ratio (HR) 0.61, 95% CI: 0.38, 0.97, p = 0.037) and alteration of PIK3CA pathway shortened the duration of survival (HR 2.25, 95% CI: 1.39, 3.63, p = 0.001). SNVs of HER2 increased survival duration, but the effect was not significant (HR: 0.58, 95% CI: 0.31, 1.08, p = 0.085). In addition, SNVs in the ERBB3 cytoplasmic domain decreased poziotinib response (HR: 4.58, 95% CI: 2.02, 10.37, p < 0.001). In multigene analysis, BC with HER2 CN >8 and intact PIK3CA pathway had significantly longer PFS compared to others (HR: 0.37, 95% CI: 0.21, 0.66, p = 0.001), while SNVs in the ERBB3 cytoplasmic domain predicted poor prognosis (HR: 4.28, 95% CI: 1.71, 10.71, p < 0.001). In conclusion, HER2 CN amplification, PIK3CA pathway alteration, and ERBB3 cytoplasmic mutation showed predictive roles on clinical outcomes of HER2-positive MBC treated with poziotinib.

Topics: Adult; Algorithms; Antineoplastic Agents; Biomarkers, Tumor; Breast Neoplasms; Exons; Female; Gene Expression; High-Throughput Nucleotide Sequencing; Humans; Middle Aged; Neoplasm Metastasis; Quinazolines; Receptor, ErbB-2

Although the introduction of human epidermal growth factor receptor (HER)2-directed therapy including trastuzumab, pertuzumab, lapatinib and trastuzumab emtansine (T-DM1) in the treatment of HER2-positive metastatic breast cancers (mBCs) favorably changed the natural history of this disease, most cases of HER2-positive mBC will eventually progress. Poziotinib is an oral pan-HER kinase inhibitor showing potent activity through irreversible inhibition of these kinases. This open-label, multicenter phase II study was designed to evaluate the efficacy and safety of poziotinib monotherapy in patients with HER2-positive mBC who had progressed from more than two HER2-directed therapies. Patients received 12 mg poziotinib once daily on a 14-day on/7-day off schedule. Progression-free survival (PFS) as the primary endpoint, the objective response rate (ORR), overall survival (OS) and safety were evaluated. From April 2015 to February 2016, 106 patients were enrolled in the trial from seven institutes in South Korea. They had a median age of 51 years (range 30-76) and had received a median of four prior therapies including two HER2-directed therapies for advanced or metastatic cancers. The median follow-up duration was 12 months. The median PFS was 4.04 months (95% confidence interval [CI], 2.94-4.40 months), and median overall survival has not been reached. The most common treatment-related adverse events were (total/grade ≥3) diarrhea (96.23%/14.15%), stomatitis (92.45%/12.26%) and rashes (63.21%/3.77%). Poziotinib showed meaningful activity in these heavily treated HER2-positive mBCs. Diarrhea and stomatitis were the major toxicities. Biomarker studies analyzed are warranted to support further evaluation of this treatment in such cases.

Topics: Adult; Aged; Antineoplastic Agents; Breast Neoplasms; Disease-Free Survival; Female; Humans; Middle Aged; Neoplasm Metastasis; Protein Kinase Inhibitors; Quinazolines; Receptor, ErbB-2; Recurrence; Republic of Korea; Survival Analysis

Topics: Aged; Carcinoma, Non-Small-Cell Lung; ErbB Receptors; Exons; Female; Humans; Lung Neoplasms; Mutation; Neoplasm Metastasis; Quinazolines