Immunochemical expression of fibroblast growth factor and its receptors in primary tumor cells of renal cell carcinoma.

BACKGROUND: There is the evidence of the role of the fibroblast growth factor and its receptors (FGF/FGFR) signaling pathway in tumorogenesis of renal cell carcinoma (RCC). We conducted a study aimed at evaluating of FGF2, FGFR1, and FGFR2 expression in primary tumor cells and assessing of these molecules expression levels effect on the characteristics of the tumor process and prognosis of patients with RCC. METHODS: Expression of FGF2, FGFR1, and FGFR2 was investigated in 65 primary RCC specimens by immuhistochemical staining using the appropriate antibodies. Expression levels were evaluated by the semi-quantitative method. A search for correlations of expression levels of investigated growth factors and receptors with RCC features and patients outcomes was performed. RESULTS: Cytoplasm and membrane expression of FGF2, FGFR1, and FGFR2 was found in the primary tumor cells of RCC patients. FGF2 staining was detected in 60.0% of cases (44.2 ± 5.4 HS). It was noted higher frequency and intensity of FGFR2 expression (66.2%; 46.6 ± 6.3 HS) comparing with FGFR1 (32.3%; 7.5 ± 2.2 HS). The correlation was revealed between the investigated markers overexpression and Fuhrman grade G3-4, as well as features of advanced RCC (paranephric fat tumor invasion, venous wall tumor invasion, adrenal and liver metastases). FGFR2 overexpression showed negative influence on cancer-specific survival in univariate analysis, however, lost its predictive value in multivariable analysis. CONCLUSION: Expression of FGF2 and its receptors was found on the surface and in the cytoplasm of RCC primary tumor cells and needs following investigations.

Alofanib, an allosteric FGFR2 inhibitor, has potent effects on ovarian cancer growth in preclinical studies.

SUMMAY: Purpose Early data suggest that combining FGFR2 inhibitors with platinum-containing cytotoxic agents for the treatment of epithelial ovarian cancer may yield increased antitumor activity. We investigated antitumor activity of alofanib (RPT835), a novel allosteric FGFR2 inhibitor, in ovarian cancer in vitro and in vivo. Methods Equal amounts of ovarian cancer cell (SKOV3) lysates were analyzed for FGFR1-3 protein expression using Wes. To assess the efficacy of alofanib on FGF-mediated cell proliferation, SKOV3 cells were incubated and were treated with serially diluted alofanib. Basic FGF was added at a concentration of 25 ng/ml. Control wells were left untreated. Cell growth inhibition was determined using Promega's Cell Titer-Glo® assay. Immunocompromised mice were used for xenotransplantation of SKOV3 cancer cells. Seventy animals with measurable tumors were selected on day 10 and randomized into control groups (no treatment or chemotherapy alone (paclitaxel + carboplatin) and treatment groups (alofanib orally or intravenously (different dose levels) in combination with chemotherapy). Measurements of tumor volume (mm3) were performed by digital calipers every 3 days during 31 days after tumor inoculation. Number of tumor vessels and Ki-67 index were calculated. Results SKOV3 cells express FGFR1 and FGFR2 but not FGFR3. Basic FGF increased proliferation of the ovarian cancer cells in untreated control group (P = 0.001). Alofanib inhibited growth of FGFR2-expressing SKOV3 cells with GI50 value of 0.37 µmol/L. Treatment with alofanib in combination with paclitaxel/carboplatin resulted in tumor growth delay phenotype in all treatment groups compared to control non-treatment groups. Compound exhibited a dose-dependent effect on tumor growth. Daily intravenous regimen of alofanib (total maximum dose per week was 350 mg/kg) demonstrated significant effect (inhibiting growth by 80 % and by 53 % in comparison with vehicle and chemotherapy group alone, respectively (P < 0.001). Alofanib decreased number of vessels in tumor (-49 %; P < 0.0001) and number of Ki-67-positive SKOV3 cells (-42 %, P < 0.05). There were tumor necrosis and cell degeneration in alofanib group. Conclusions We suggest that FGFR2 inhibition has potent effects on ovarian cancer growth in preclinical studies.

Targeting FGFR2 with alofanib (RPT835) shows potent activity in tumour models.

Alofanib (RPT835) is a novel selective allosteric inhibitor of fibroblast growth factor receptor 2 (FGFR2). We showed previously that alofanib could bind to the extracellular domain of FGFR2 and has an inhibitory effect on FGF2-induced phoshphorylation of FRS2α. In the present study, we further showed that alofanib inhibited phosphorylation of FRS2α with the half maximal inhibitory concentration (IC50) values of 7 and 9 nmol/l in cancer cells expressing different FGFR2 isoforms. In a panel of four cell lines representing several tumour types (triple-negative breast cancer, melanoma, and ovarian cancer), alofanib inhibited FGF-mediated proliferation with 50% growth inhibition (GI50) values of 16-370 nmol/l. Alofanib dose dependently inhibited the proliferation and migration of human and mouse endothelial cells (GI50 11-58 nmol/l) compared with brivanib and bevacizumab. Treatment with alofanib ablated experimental FGF-induced angiogenesis in vivo. In a FGFR-driven human tumour xenograft model, oral administration of alofanib was well tolerated and resulted in potent antitumour activity. Importantly, alofanib was effective in FGFR2-expressing models. These results show that alofanib is a potent FGFR2 inhibitor and provide strong rationale for its evaluation in patients with FGFR2-driven cancers.