[show abstract][hide abstract] ABSTRACT: To identify novel genetic markers predictive of clinical benefit from epidermal growth factor receptor-directed antibody therapy in patients with metastatic colorectal cancer.
Seventy-six consecutive patients who received cetuximab or panitumumab, either alone or in combination with chemotherapy and with available tumor tissue were included. Tumor tissue was tested by pyrosequencing for mutations at known hot spots in the KRAS, BRAF, PIK3CA, PIK3R1, AKT1, and PTEN genes. PTEN promoter methylation status was analyzed by methylation-specific polymerase chain reaction, and expression was determined by immunohistochemistry (IHC). Forty-four patients had 4 weeks of therapy and were considered for clinical correlates.
Consistent with previous studies, KRAS gene mutations were associated with a shorter progression-free survival (PFS) and overall survival (OS). Among the patients with wild-type KRAS, preservation of PTEN expression and PIK3CA wild-type status was associated with improved OS (median OS, 80.4 vs. 32.5 weeks; hazard ratio, 0.33; P = .0008) and a trend toward improved PFS (median PFS, 24.8 vs. 15.2 weeks; hazard ratio, 0.51; P = .06), compared with PTEN-negative or PIK3CA-mutant tumors. PTEN methylation was more common in the metastatic samples than in the primary samples (P = .02). The simultaneous presence of methylation and mutation in the PTEN gene was associated with IHC negativity (P = .026).
In addition to KRAS mutation, loss of PTEN expression (by IHC) and PIK3CA mutation is likely to be predictive of a lack of benefit to anti-EGFR therapy in metastatic colorectal cancer. PTEN promoter methylation and mutation status was predictive of PTEN expression and may be used as an alternative means of predicting response to EGFR-targeted therapy.
Clinical Colorectal Cancer 01/2012; 11(2):143-50. · 1.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: The nuclear receptor pregnane X receptor (PXR) is activated by a range of xenochemicals, including chemotherapeutic drugs, and has been suggested to play a role in the development of tumor cell resistance to anticancer drugs. PXR also has been implicated as a regulator of the growth and apoptosis of colon tumors. Here, we have used a xenograft model of colon cancer to define a molecular mechanism that might underlie PXR-driven colon tumor growth and malignancy. Activation of PXR was found to be sufficient to enhance the neoplastic characteristics, including cell growth, invasion, and metastasis, of both human colon tumor cell lines and primary human colon cancer tissue xenografted into immunodeficient mice. Furthermore, we were able to show that this PXR-mediated phenotype required FGF19 signaling. PXR bound to the FGF19 promoter in both human colon tumor cells and "normal" intestinal crypt cells. However, while both cell types proliferated in response to PXR ligands, the FGF19 promoter was activated by PXR only in cancer cells. Taken together, these data indicate that colon cancer growth in the presence of a specific PXR ligand results from tumor-specific induction of FGF19. These observations may lead to improved therapeutic regimens for colon carcinomas.
The Journal of clinical investigation 08/2011; 121(8):3220-32. · 15.39 Impact Factor
[show abstract][hide abstract] ABSTRACT: To determine the maximum tolerated dose of oblimersen, an antisense oligonucleotide directed to the Bcl-2 mRNA, in combination with cisplatin and 5-flourouracil in patients with advanced gastric and esophageal carcinoma.
Patients were treated with escalating doses of oblimersen administered by continuous intravenous infusion (CIVI) days 1 to 7, CIVI 5-fluorouracil (5-FU) days 4 to 7, and cisplatin on day 4 every 3 weeks.
Fifteen patients received a total of 49 courses of oblimersen at doses of 3, 5, or 7 mg/kg/d given as a 7 day CIVI in combination with 4 or 5 day CIVI of 5-FU (1000 or 750 mg/m2/d) plus intravenous cisplatin (100 or 75 mg/m2 over 2 hours). The recommended phase II dose of oblimersen was 5 mg/kg/d in combination with 5-FU (750 mg/m2/d for 4 days) and cisplatin (75 mg/m). The most common grade 3 to 4 adverse events that occurred in at least 10% of patients at all dose levels included neutropenia (33%), hypokalemia (27%), infection (20%), and mucositis, fatigue, dizziness, thrombosis, and dehydration (in 13% for each category).
The combination of oblimersen with 5-FU and cisplatin chemotherapy is feasible in patients with advanced upper gastrointestinal cancer, with antitumor activity observed in gastric carcinoma.
American journal of clinical oncology 01/2010; 33(1):61-65. · 2.21 Impact Factor
[show abstract][hide abstract] ABSTRACT: To determine the efficacy and toxicity of the protein kinase C inhibitor bryostatin-1 plus paclitaxel in patients with advanced pancreatic carcinoma.
Each treatment cycle consisted of paclitaxel 90 mg/m by intravenous infusion over 1 hour on days 1, 8, and 16, plus bryostatin 25 mcg/m as a 1-hour intravenous infusion on days 2, 9, and 15, given every 28 days. Patients were evaluated for response after every 2 treatment cycles, and continued therapy until disease progression or prohibitive toxicity. The primary objective was to determine whether the combination produced a response rate of at least 30%.
Nineteen patients with locally advanced or metastatic pancreatic adenocarcinoma received a total of 52 cycles of therapy (range: 1-10). Patients received the combination as first-line therapy for advanced disease (N = 5) or after prior chemotherapy used alone or in combination with local therapy. No patients had a confirmed objective response. The median time to treatment failure was 1.9 months (95% confidence intervals: 1.2, 2.6 months). Reasons for discontinuing therapy included progressive disease or death in 14 patients (74%) or because of adverse events or patient choice in 5 patients (26%). The most common grade 3 to 4 toxicities included leukopenia in 26%, anemia in 11%, myalgias in 11%, gastrointestinal bleeding in 11%, infection in 10%, and thrombosis in 10%.
The combination of weekly paclitaxel and bryostatin-1 is not an effective therapy for patients with advanced pancreatic carcinoma.
American journal of clinical oncology 10/2009; 33(2):121-4. · 2.21 Impact Factor
[show abstract][hide abstract] ABSTRACT: Capecitabine and irinotecan have demonstrated in vitro synergistic anti-cancer activity, and both are substrates for carboxyl esterases (CES). We conducted a study to identify a safe dose and potential drug-drug interactions of this combination.
This was an open-label phase I dose escalation trial. Irinotecan was given as a 30 min infusion on days 1 and 8, and capecitabine on days 1-14 of a 21-day cycle. Plasma for pharmacokinetic analyses was drawn on days 1 and 8.
Forty-seven patients with advanced solid tumors received 202 cycles of chemotherapy in 6 dose cohorts. At the highest dose tested, 1 of 3 patients developed fatal neutropenia and gram-negative sepsis. At dose level 5 (100/2000), 2 of 28 patients developed cycle 1 DLT-grade 3 diarrhea/vomiting, and grade 3 diarrhea. Responses were observed in 9 of 35 (5 of 9 ovarian cancer) evaluable patients. The AUC((0-last)) of irinotecan, SN-38G, and APC were similar on days 1 and 8. However, SN-38 T(max) was longer on Day 8 (0.88 h vs. 1.23 h, p = 0.012). While SN-38 AUC((0-last)) was lower on day 8 by 35%, this was not statistically significant (p = 0.123).
Capecitabine results in a significantly delayed conversion of irinotecan to SN-38, suggesting drug-drug interaction at the level of CES. This suggests caution should be used when irinotecan is combined with substrates of CES, and warrants further study. The combination of irinotecan and capecitabine is safe and well tolerated at 100/2000, and warrants further evaluation in ovarian and breast cancer.
Investigational New Drugs 07/2007; 25(3):237-45. · 3.50 Impact Factor