Control of RhoA methylation by carboxylesterase I.

A number of proteins that play key roles in cell signaling are post-translationally modified by the prenylation pathway. The final step in this pathway is methylation of the carboxyl terminus of the prenylated protein by isoprenylcysteine carboxylmethyltransferase. Due to the impact of methylation on Rho function, we sought to determine if the process was reversible and hence could control Rho function in a dynamic fashion. Elevating isoprenylcysteine carboxylmethyltransferase activity in cells has profound effects on MDA-MB-231 cell morphology, implying the presence of a pool of unmethylated prenyl proteins in these cells under normal conditions. Using a knockdown approach, we identified a specific esterase, carboxylesterase 1, whose function had a clear impact not only on the methylation status of RhoA but also RhoA activation and cell morphology. These data provide compelling evidence that C-terminal modification of prenyl proteins, rather than being purely a constitutive process, can serve as a point of regulation of function for this important class of protein.

Phase I study of capecitabine, oxaliplatin, bevacizumab, and everolimus in advanced solid tumors.

PURPOSE: To define maximum tolerated dose (MTD), toxicities, and pharmacodynamics of capecitabine, oxaliplatin, bevacizumab, and everolimus in advanced solid tumor patients. DESIGN: This was a standard "3 + 3" dose-escalation trial. All subjects received bevacizumab 7.5 mg/kg on day 1 of each cycle. Doses for capecitabine, oxaliplatin and everolimus were modified per dose limiting toxicity (DLT). Baseline and on-treatment plasma biomarkers were analyzed. Archived tumor mRNA levels were evaluated for NRP1, NRP2 and VEGF-A isoforms. RESULTS: Twenty-nine patients were evaluable for toxicity and 30 for efficacy. Two DLTs were observed in cohort 1 and one DLT each was observed in cohort -1 and -1b. Grade ≥3 toxicities included neutropenia, hypertension, perforation/fistula/hemorrhage, hypertriglyceridemia, diarrhea, and thromboembolism. Twelve subjects experienced partial response (PR); 12 had stable disease as best response. Three of seven chemorefractory metastatic colorectal cancer (mCRC) subjects experienced PR; 8 of 15 chemonaive mCRC subjects experienced PR. Plasma TßRIII and IL-6 increased on treatment but without correlation to outcome. Increased VEGF165 levels significantly correlated with longer progression free survival. CONCLUSIONS: Everolimus with full dose capecitabine, oxaliplatin, and bevacizumab had unacceptable toxicity. MTD was: everolimus 5 mg daily; capecitabine 680 mg/m(2) BID days 1-14; oxaliplatin 100 mg/m(2) and bevacizumab 7.5 mg/kg, day 1. Activity was noted in mCRC.

A phase II study of capecitabine, oxaliplatin, and bevacizumab in the treatment of metastatic esophagogastric adenocarcinomas.

BACKGROUND: Esophageal and gastric cancers often present at an advanced stage. Systemic chemotherapy is the mainstay of treatment, but survival with current regimens remains poor. We evaluated the safety, tolerability, and efficacy of the combination capecitabine, oxaliplatin, and bevacizumab in the treatment of metastatic esophagogastric adenocarcinomas. METHODS: Thirty-seven patients with metastatic or unresectable gastric/gastroesophageal junction tumors were enrolled and treated with capecitabine 850 mg/m(2) BID on days 1-14, and oxaliplatin 130 mg/m(2) with bevacizumab 15 mg/kg on day 1 of a 21-day cycle. The primary endpoint was progression-free survival (PFS). Secondary endpoints included response rate (RR) and overall survival (OS). Neuropilin-1 (NRP1) and -2 (NRP2) mRNA expression was evaluated in archived tumor. RESULTS: Thirty-five patients were evaluable for efficacy. Median PFS was 7.2 months; median OS was 10.8 months. RR was estimated at 51.4%. The regimen was tolerable with expected drug class-related toxicities. NRP2 mRNA levels significantly correlated with PFS (p = 0.042) and showed a trend toward significance with OS (p = 0.051). Nonsignificant trends for NRP1 were noted for higher expression levels and worse outcome. CONCLUSIONS: Bevacizumab can be given safely with chemotherapy in patients with metastatic esophagogastric adenocarcinomas. The combination of capecitabine, oxaliplatin, plus bevacizumab has activity comparable to other bevacizumab-containing regimens in metastatic gastroesophageal cancer.

Gene expression markers of efficacy and resistance to cetuximab treatment in metastatic colorectal cancer: results from CALGB 80203 (Alliance).

PURPOSE: Formalin-fixed, paraffin-embedded tumor samples from CALGB 80203 were analyzed for expression of EGFR axis-related genes to identify prognostic or predictive biomarkers for cetuximab treatment. PATIENTS AND METHODS: Patients (238 total) with first-line metastatic colorectal cancer (mCRC) were randomized to FOLFOX or FOLFIRI chemotherapy ± cetuximab. qRT-PCR analyses were conducted on tissues from 103 patients at baseline to measure gene expression levels of HER-related genes, including amphiregulin (AREG), betacellulin (BTC), NT5E (CD73), DUSP4, EGF, EGFR, epigen (EPGN), epiregulin (EREG), HBEGF, ERBB2 (HER2), ERBB3 (HER3), ERBB4 (HER4), PHLDA1, and TGFA. The interactions between expression levels and treatment with respect to progression-free survival (PFS) and overall survival (OS) were modeled using multiplicative Cox proportional hazards models. RESULTS: High tumor mRNA levels of HER2 [hazard ratio (HR), 0.64; P = 0.002] and EREG (HR, 0.89; P = 0.016) were prognostic markers associated with longer PFS across all patients. HER3 and CD73 expression levels were identified as potential predictive markers of benefit from cetuximab. In KRAS wild-type (WT) tumors, low HER3 expression was associated with longer OS from cetuximab treatment, whereas high HER3 expression was associated with shorter OS from cetuximab treatment (chemo + cetuximab: HR, 1.15; chemo-only: HR, 0.48; Pinteraction = 0.029). High CD73 expression was associated with longer PFS from cetuximab treatment in patients with KRAS-WT (chemo + cetuximab: HR, 0.91; chemo-only: HR, 1.57; Pinteraction = 0.026) and KRAS-mutant (Mut) tumors (chemo + cetuximab: HR, 0.80; chemo-only: HR, 1.29; P = 0.025). CONCLUSIONS: Gene expression of HER3 and CD73 was identified as a potential predictive marker for cetuximab. These data implicate HER axis signaling and immune modulation as potential mechanisms of cetuximab action and sensitivity.

A phase I study of ABT-510 plus bevacizumab in advanced solid tumors.

Targeting multiple regulators of tumor angiogenesis have the potential to improve treatment efficacy. Bevacizumab is a monoclonal antibody directed against vascular endothelial growth factor and ABT-510 is a synthetic analog of thrombospondin, an endogenous angiogenesis inhibitor. Dual inhibition may result in additional benefit. We evaluated the safety, tolerability, and efficacy of the combination of bevacizumab plus ABT-510 in patients with refractory solid tumors. We also explored the effects of these agents on plasma-based biomarkers and wound angiogenesis. Thirty-four evaluable subjects were enrolled and received study drug. Therapy was well tolerated; minimal treatment-related grade 3/4 toxicity was observed. One patient treated at dose level 1 had a partial response and five other patients treated at the recommended phase II dose had prolonged stable disease for more than 1 year. Biomarker evaluation revealed increased levels of D-dimer, von Willebrand factor, placental growth factor, and stromal-derived factor 1 in response to treatment with the combination of bevacizumab and ABT-510. Data suggest that continued evaluation of combination antiangiogenesis therapies may be clinically useful.