Systemic chemotherapy options for metastatic bladder cancer

Systemic chemotherapy has reached a therapeutic plateau in the treatment of transitional cell carcinomas of the urothelium. Since the advent of the combination of methotrexate, vinblastine, adriamycin and cisplatin (MVAC) in the 1980s, no chemotherapy regimen has been proven to be superior to this therapy. Only one regimen, a combination of gemcitabine and cisplatin, has been equivalent. With a similar response rate and survival, plus the benefit of an improved toxicity profile, the gemcitabine cisplatin combination has largely supplanted MVAC in physician’s practices. Although a recent dose-intense version of MVAC has shown an improved toxicity profile compared with traditional MVAC, it is clear that, for many patients, a full-dose cisplatin-based chemotherapy regimen may not be a tolerable option. Tobacco use, which is a common risk factor predisposing for the development of transitional cell carcinoma, may also cause morbidities that preclude treatment with aggressive combination therapy. Therefore, there is a clear need for regimens with improved toxicity, especially for the frequently frail or elderly patient population with poor renal function. There is an additional unmet requirement in rare bladder tumors, for which treatment has traditionally been based upon anecdotal evidence, limited by small patient numbers. Currently, there is newfound hope for all bladder cancer patients, with investigators studying new combinations and novel treatment paradigms, with recent studies focusing on frail, or ‘cisplatin-unfit’, patients and additional studies in the setting of rare small cell or urachal carcinoma patients.     

Stoichiometry,Kinetic and Binding Analysis of the Interaction between Epidermal Growth Factor (EGF) and the Extracellular Domain of the EGF Receptor

Abstract

The kinetics, binding equilibria and stoichiometry of the interaction between epidermal growth factor and the soluble extracellular domain of the epidermal growth factor receptor (sEGFR), produced in CHO cells using a bioreactor, have been studied by three methods: analytical ultracentrifugation, biosensor analysis using surface plasmon resonance detection (BIAcore 2000) and fluorescence anisotropy. These studies were performed with an sEGFR preparation purified in the absence of detergent using a mild two step chromatographic procedure employing anion exchange and size exclusion HPLC. The fluorescence anisotropy and analytical ultracentrifugation data indicated a 1:1 molar binding ratio between EGF and the sEGFR. Analytical ultracentrifugation further indicated that the complex comprised 2EGF: 2sEGFR, consistent with the model proposed recently by Lemmon et al. (1997). Global analysis of the BIAcore binding data showed that a simple Langmuirian interaction does not adequately describe the EGF: sEGFR interaction and that more complex interaction mechanisms are operative. Furthermore, analysis of solution binding data using either fluorescence anisotropy or the biosensor, to determine directly the concentration of free sEGFR in solution competition experiments, yielded Scatchard plots which were biphasic and Hill coefficients of less than unity. Taken together our data indicate that in solution there are two sEGFR populations; one which binds EGF with a K_D of 2–20 nM and the other with a K_D of 400–550 nM.     

A phase II randomized trial evaluating gefitinib intercalated with pemetrexed/platinum chemotherapy or pemetrexed/platinum chemotherapy alone in unselected patients with advanced non-squamous non-small cell lung cancer

Current pemetrexed/platinum chemotherapy does not produce a satisfactory therapeutic response in advanced lung cancer patients. The aim of this study was to determine whether the administration of gefitinib, a tyrosine kinase inhibitor (TKI), intercalated with pemetrexed/platinum could improve the efficacy in chemotherapy-naïve patients with advanced non-squamous NSCLC without subsequent gefitinib maintenance therapy. Treatment-naïve patients with stage IIIB or IV NSCLC were randomly assigned to receive pemetrexed (500 mg/m² d1) and either cisplatin (75 mg/m² d1) or carboplatin (AUC = 5 d1) plus gefitinib (250 mg/d on days 3 to 16 of a 3-week cycle) (PC-G) or pemetrexed–platinum (PC) alone. Randomization was stratified according to the tobacco smoking status and EGFR mutational status of the patients. The primary endpoint was the non-progression rate (NPR) at 12 weeks. Secondary endpoints included progression-free survival (PFS), overall response rate (ORR), overall survival (OS), and biosafety. The NPR at 12 weeks was 84.5% for the PC-G treatment arm and 83.1% for the PC treatment arm (P = 0.87). Median PFS was 7.9 months for the PC-G arm and 7.0 months for the PC arm (P = 0.57). The ORR was 50.0% for the PC-G arm and 47.4% for the PC arm (P = 0.78). Median survival was 25.4 mo for the PC-G arm and 20.8 mo for the PC arm (P = 0.54). The incidence of adverse events was similar between the two treatment arms, except for a higher incidence of skin rash with PC-G. Predefined subgroup analyses demonstrated that PC-G significantly increased the PFS compared with the PC regimen in patients with EGFR mutations (P = 0.017). Although gefitinib intercalated with pemetrexed/platinum chemotherapy did not improve the NPR at 12 weeks compared with chemotherapy, an improvement in the PFS for the intercalated treatment arm was seen in the subgroup of patients with EGFR mutations.     

Preclinical Evaluation of MET Inhibitor INC-280 With or Without the Epidermal Growth Factor Receptor Inhibitor Erlotinib in Non–Small-Cell Lung Cancer

BackgroundAlthough the epidermal growth factor receptor (EGFR) inhibitor erlotinib is initially effective in non–small-cell lung cancer (NSCLC) patients with tumors harboring activating mutations of EGFR, most subsequently develop acquired resistance. One recognized resistance mechanism occurs through activation of bypass signaling via the hepatocyte growth factor (HGF)-MET pathway. INC-280 is a small molecule kinase inhibitor of MET. We sought to demonstrate the activity of INC-280 on select NSCLC cell lines both as a single agent and in combination with erlotinib using exogenous HGF to simulate MET up-regulation.MethodsFour NSCLC cell lines (HCC827, PC9, H1666, and H358) were treated with either single-agent INC-280 or in combination with erlotinib with or without HGF. The activity of the drug treatments was measured by cell viability assays. Immunoblotting was used to monitor expression of EGFR/pEGFR, MET/pMET, GAB1/pGAB1, AKT/pAKT, and ERK/pERK as well as markers of apoptosis (PARP and capase-3 cleavage) in H1666, HCC827, and PC9.ResultsAs a single agent, INC-280 showed minimal cytotoxicity despite potent inhibition of MET kinase activity at concentrations as low as 10 nM. Addition of HGF prevented erlotinib-induced cell death. The addition of INC280 to HGF-mediated erlotinib-resistant models restored erlotinib sensitivity for all cell lines tested, associated with cleavage of both PARP and caspase-3. In these models, INC-280 treatment was sufficient to restore erlotinib-induced inhibition of MET, GAB1, AKT, and ERK in the presence of HGF.ConclusionAlthough the MET inhibitor INC-280 alone had no discernible effect on cell growth, it was able to restore sensitivity to erlotinib and promote apoptosis in NSCLC models rendered erlotinib resistant by HGF. These data provide a preclinical rationale for an ongoing phase 1 clinical trial of erlotinib plus INC-280 in EGFR-mutated NSCLC.