Minaxi Jhawer

PIK3CA Mutation/PTEN Expression Status Predicts Response of Colon Cancer Cells to the Epidermal Growth Factor Receptor Inhibitor Cetuximab

Cetuximab is a monoclonal antibody that targets the human epidermal growth factor receptor (EGFR). Although approved for use in EGFR-overexpressing advanced colorectal cancer, recent studies have shown a lack of association between EGFR overexpression and cetuximab response, requiring the identification of novel biomarkers predictive of response to this agent. To do so, 22 colon cancer cell lines were screened for cetuximab response in vitro and sensitive and resistant lines were identified. In sensitive cell lines, cetuximab induced a G(0)-G(1) arrest without inducing apoptosis. Notably, cetuximab-sensitive but not cetuximab-resistant cell lines were preferentially responsive to EGF-stimulated growth. Whereas neither EGFR protein/mRNA expression nor gene copy number correlated with cetuximab response, examination of the mutation status of signaling components downstream of EGFR showed that cell lines with activating PIK3CA mutations or loss of PTEN expression (PTEN null) were more resistant to cetuximab than PIK3CA wild type (WT)/PTEN-expressing cell lines (14 +/- 5.0% versus 38.5 +/- 6.4% growth inhibition, mean +/- SE; P = 0.008). Consistently, PIK3CA mutant isogenic HCT116 cells showed increased resistance to cetuximab compared with PIK3CA WT controls. Furthermore, cell lines that were PIK3CA mutant/PTEN null and Ras/BRAF mutant were highly resistant to cetuximab compared with those without dual mutations/PTEN loss (10.8 +/- 4.3% versus 38.8 +/- 5.9% growth inhibition, respectively; P = 0.002), indicating that constitutive and simultaneous activation of the Ras and PIK3CA pathways confers maximal resistance to this agent. A priori screening of colon tumors for PTEN expression status and PIK3CA and Ras/BRAF mutation status could help stratify patients likely to benefit from this therapy.

Phase II Study of Modified Docetaxel, Cisplatin, and Fluorouracil With Bevacizumab in Patients With Metastatic Gastroesophageal Adenocarcinoma

PURPOSE To evaluate the safety and efficacy of a modified administration schedule of docetaxel, cisplatin, and fluorouracil (mDCF) with bevacizumab in patients with advanced gastroesophageal malignancies. PATIENTS AND METHODS Previously untreated patients with metastatic gastroesophageal adenocarcinoma received bevacizumab 10 mg/kg, docetaxel 40 mg/m², fluorouracil 400 mg/m², leucovorin 400 mg/m² on day 1, fluorouracil 1,000 mg/m²/d × 2 days intravenous continuous infusion beginning on day 1, and cisplatin 40 mg/m² on day 3. The primary objective was to improve 6-month progression-free survival (PFS) from 43% (historical DCF control) to 63% with the addition of bevacizumab. The target accrual was 44 patients to have 10% type I and II error rates. RESULTS In total, 44 eligible patients with cancer were enrolled from October 2006 to October 2008: 22 gastric, 20 gastroesophageal junction (GEJ), and two esophagus. In 39 patients with measurable disease, the confirmed response rate was 67% (95% CI, 50% to 81%). Six-month PFS was 79% (95% CI, 63% to 88%), and median PFS was 12 months (95% CI, 8.8 to 18.2 months). With 26-month follow-up, median overall survival (OS) was 16.8 months (95% CI, 12.1 to 26.1 months), and 2-year survival was 37%. Treatment-related grade 3 to 4 toxicity was as follows: neutropenia without fever (50%), fatigue (25%), venous thromboembolism (39%), and nausea, vomiting, mucositis, neuropathy, and febrile neutropenia less than 10% each. In subset analysis, diffuse gastric cancer had significantly worse PFS and OS, and the response rate in proximal/GEJ tumors was 85% (95% CI, 62% to 97%). CONCLUSION mDCF with bevacizumab appears tolerable and has notable patient outcomes in patients with advanced gastroesophageal adenocarcinoma. Six-month PFS was 79%, surpassing our predefined efficacy end point, and median and 2-year OS were 16.8 months and 37%, respectively.

Apoptotic Sensitivity of Colon Cancer Cells to Histone Deacetylase Inhibitors Is Mediated by an Sp1/Sp3-Activated Transcriptional Program Involving Immediate-Early Gene Induction

Histone deacetylase inhibitors (HDACi) induce growth arrest and apoptosis in colon cancer cells and are being considered for colon cancer therapy. The underlying mechanism of action of these effects is poorly defined with both transcription-dependent and -independent mechanisms implicated. We screened a panel of 30 colon cancer cell lines for sensitivity to HDACi-induced apoptosis and correlated the differences with gene expression patterns induced by HDACi in the five most sensitive and resistant lines. A robust and reproducible transcriptional response involving coordinate induction of multiple immediate-early (fos, jun, egr1, egr3, atf3, arc, nr4a1) and stress response genes (Ndrg4, Mt1B, Mt1E, Mt1F, Mt1H) was selectively induced in HDACi sensitive cells. Notably, a significant percentage of these genes were basally repressed in colon tumors. Bioinformatics analysis revealed that the promoter regions of the HDACi-induced genes were enriched for KLF4/Sp1/Sp3 transcription factor binding sites. Altering KLF4 levels failed to modulate apoptosis or transcriptional responses to HDACi treatment. In contrast, HDACi preferentially stimulated the activity of Spl/Sp3 and blocking their action attenuated both the transcriptional and apoptotic responses to HDACi treatment. Our findings link HDACi-induced apoptosis to activation of a Spl/Sp3-mediated response that involves derepression of a transcriptional network basally repressed in colon cancer.

Phase I clinical trial of irinotecan with oral capecitabine in patients with gastrointestinal and other solid malignancies.

The purpose of this study was to determine the safety of irinotecan and capecitabine in patients with advanced solid tumors. Thirty-four patients received 122 courses of irinotecan 200 to 300 mg/m2 as an intravenous infusion during 30 minutes on day 1 and capecitabine 1,500 to 3,000 mg/d orally 12 hours apart starting on day 2 for 14 days, repeated every 21 days (one course). Three to seven patients were treated in six dose-escalation cohorts. Three of 7 (43%) patients treated with irinotecan 300 mg/m2 and capecitabine 2,300 mg/d had course 1 dose-limiting toxicity (DLT) defining maximum tolerated dosage (MTD). Fatigue and diarrhea were the major DLTs, and other events included neutropenia, anorexia, and hand–foot syndrome. At one dose level below the MTD, none of 7 patients treated with irinotecan 275 mg/m2, and capecitabine 2,300 mg/d (36 courses) had course 1 DLT. Grade III to IV toxicities beyond course 1 included neutropenia (11% of all courses), fatigue (3.4%) and hand–foot syndrome (3.4%). There were only two episodes of febrile grade II neutropenia. There were no toxic deaths. Transient antitumor response was noted in one patient with irinotecan and 5-fluorouracil-refractory colon cancer. The combination of irinotecan 275 mg/m2 and capecitabine 2,300 mg/d represents a safe, favorable, and convenient outpatient regimen warranting further phase II evaluation.

Perineural invasion after preoperative chemotherapy predicts poor survival in patients with locally advanced gastric cancer: gene expression analysis with pathologic validation.

Background:We examined gene expression profiles and clinicopathologic features (tumor location, stage, graded pathologic response, perineural invasion (PNI), Lauren’s classification, and survival) of patients with gastric cancer who received preoperative chemotherapy to identify prognostic markers. Methods:Thirty-eight patients with locally advanced gastric cancer received preoperative chemotherapy on a phase II trial. Twelve fresh-frozen tumor samples were available for RNA expression analysis. Differential gene expression between tumors with and without PNI was identified and correlated with clinicopathologic features. Results:Preliminary hierarchical clustering suggested a separation between long- and short-term survivors. The close association between PNI and overall survival was identified and validated immunohistochemically in 31 completely resected gastric tumors. Five-year survival for patients with PNI and without PNI was 5% and 65%, respectively (P < 0.01). PNI added significant prognostic value to posttreatment pathologic stage, (P < 0.01). Differential gene expression profile for PNI and non-PNI tumors identified 111 potentially relevant genes. Conclusions:Our results demonstrate that the presence of PNI after preoperative chemotherapy is associated with poor survival. These results need to be validated in prospective studies, to help establish whether patients with evidence of PNI would be candidates for more aggressive therapy or enrollment into clinical trials. The presence of PNI provides additional prognostic importance to posttreatment pathologic stage and may indicate treatment resistance. Understanding the molecular events associated with PNI, may provide insight into new therapeutic agents for this subset of patients with resistant tumors.

Chemotherapy toxicity predicted by baseline nutrition assessment in gastrointestinal (GI) malignancies: A multicenter analysis.

410 Background: Malnutrition is prevalent in GI malignancies and is associated with decreased survival, frequent hospitalizations and increased healthcare costs. Outside the perioperative setting, malnutrition rarely impacts treatment decisions. The subjective global assessment (SGA) is a validated tool that stratifies patients by nutritional status. We hypothesized that malnutrition independently predicts chemotherapy-related toxicity in patients with GI malignancies. Methods: All patients enrolled in the GI Cancer Registry which collects baseline demographic data, comorbid conditions and baseline nutrition status. In patients treated with chemotherapy, we reviewed dosing, schedule and toxicities over the first two months of treatment and compared results between well-nourished (SGA-A) and malnourished (SGA B/C) patients. Two-sample t-test or chi-square tests were used for comparisons as appropriate. Multivariable logistic regression analysis was used to estimate the independent effect of SGA status afte...