Phase II Study of Dovitinib in Patients with Castration-Resistant Prostate Cancer (KCSG-GU11-05) / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Fibroblast growth factor (FGF) signals are important in carcinogenesis and progression of prostate cancer. Dovitinib is an oral, pan-class inhibitor of vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor, and fibroblast growth factor receptor (FGFR). We evaluated the efficacy and toxicity of dovitinib in men with metastatic castration resistant prostate cancer (mCRPC). MATERIALS AND METHODS: This study was a single-arm, phase II, open-label, multicenter trial of dovitinib 500 mg/day (5-days-on/2-days-off schedule). The primary endpoint was 16-week progression-free survival (PFS). Secondary endpoints were overall survival (OS), toxicity and prostate-specific antigen (PSA) response rate. Biomarker analyses for VEGFR2, FGF23, and FGFR2 using multiplex enzyme-linked immunosorbent assay was performed. RESULTS: Forty-four men were accrued from 11 hospitals. Eighty percent were post-docetaxel. Median PSA was 100 ng/dL, median age was 69, 82% had bone metastases, and 23% had liver metastases. Median cycles of dovitinib was 2 (range, 0 to 33). Median PFS was 3.67 months (95% confidence interval [CI], 1.36 to 5.98) and median OS was 13.70 months (95% CI, 0 to 27.41). Chemotherapy-naïve patients had longer PFS (17.90 months; 95% CI, 9.23 to 28.57) compared with docetaxel-treated patients (2.07 months; 95% CI, 1.73 to 2.41; p=0.001) and the patients with high serum VEGFR2 level over median level (7,800 pg/mL) showed longer PFS compared with others (6.03 months [95% CI, 4.26 to 7.80] vs. 1.97 months [95% CI, 1.79 to 2.15], p=0.023). Grade 3 related adverse events were seen in 40.9% of patients. Grade 1-2 nausea, diarrhea, fatigue, anorexia, and all grade thrombocytopenia are common. CONCLUSION: Dovitinib showed modest antitumor activity with manageable toxicities in men with mCRPC. Especially, patients who were chemo-naïve benefitted from dovitinib.

Nonmetastatic Castration-Resistant Prostate Cancer

After the introduction of prostate cancer screening with the prostate-specific antigen (PSA) test, we have witnessed a dramatic stage migration. As a result, an increasing number of patients are diagnosed at earlier stages and receive local treatments including surgery or radiation. When these local treatments fail by the definition of increasing PSA levels, patients are usually treated with androgen-deprivation therapy. A fraction of these patients will finally reach a state of castration-resistant prostate cancer (CRPC) even without radiological evidence of metastasis, which is referred to as nonmetastatic CRPC (NM-CRPC). Most men with advanced or metastatic prostate cancer initially respond to various types of androgen ablation, but a considerable portion of them eventually progress to NM-CRPC. Among patients with NM-CPRC, about one-third will develop bone metastasis within 2 years. In these patients, PSA kinetics is the most powerful indicator of progression and is usually used to trigger further imaging studies and enrollment in clinical trials. Although CRPC remains largely driven by the androgen receptor, the benefit of second-line hormonal manipulations, including first-generation antiandrogens, adrenal synthesis inhibitors, and steroids, has not been investigated in men with NM-CRPC. To date, denosumab is the only agent that has been shown to delay the onset of bone metastasis. However, overall survival did not differ. In treating NM-CRPC patients, physicians should recognize the heterogeneity of the disease and acknowledge that the recently approved second-line treatments have been studied only in advanced stages of the disease.