Charles D. Blanke

Adjuvant imatinib mesylate after resection of localised, primary gastrointestinal stromal tumour: a randomised, double-blind, placebo-controlled trial

BACKGROUND Gastrointestinal stromal tumour is the most common sarcoma of the intestinal tract. Imatinib mesylate is a small molecule that inhibits activation of the KIT and platelet-derived growth factor receptor alpha proteins, and is effective in first-line treatment of metastatic gastrointestinal stromal tumour. We postulated that adjuvant treatment with imatinib would improve recurrence-free survival compared with placebo after resection of localised, primary gastrointestinal stromal tumour. METHODS We undertook a randomised phase III, double-blind, placebo-controlled, multicentre trial. Eligible patients had complete gross resection of a primary gastrointestinal stromal tumour at least 3 cm in size and positive for the KIT protein by immunohistochemistry. Patients were randomly assigned, by a stratified biased coin design, to imatinib 400 mg (n=359) or to placebo (n=354) daily for 1 year after surgical resection. Patients and investigators were blinded to the treatment group. Patients assigned to placebo were eligible to crossover to imatinib treatment in the event of tumour recurrence. The primary endpoint was recurrence-free survival, and analysis was by intention to treat. Accrual was stopped early because the trial results crossed the interim analysis efficacy boundary for recurrence-free survival. This study is registered with ClinicalTrials.gov, number NCT00041197. FINDINGS All randomised patients were included in the analysis. At median follow-up of 19.7 months (minimum-maximum 0-56.4), 30 (8%) patients in the imatinib group and 70 (20%) in the placebo group had had tumour recurrence or had died. Imatinib significantly improved recurrence-free survival compared with placebo (98% [95% CI 96-100] vs 83% [78-88] at 1 year; hazard ratio [HR] 0.35 [0.22-0.53]; one-sided p<0.0001). Adjuvant imatinib was well tolerated, with the most common serious events being dermatitis (11 [3%] vs 0), abdominal pain (12 [3%] vs six [1%]), and diarrhoea (ten [2%] vs five [1%]) in the imatinib group and hyperglycaemia (two [<1%] vs seven [2%]) in the placebo group. INTERPRETATION Adjuvant imatinib therapy is safe and seems to improve recurrence-free survival compared with placebo after the resection of primary gastrointestinal stromal tumour. FUNDING US National Institutes of Health and Novartis Pharmaceuticals.

Updated Analysis of SWOG-Directed Intergroup Study 0116: A Phase III Trial of Adjuvant Radiochemotherapy Versus Observation After Curative Gastric Cancer Resection

PURPOSE Surgical resection of gastric cancer has produced suboptimal survival despite multiple randomized trials that used postoperative chemotherapy or more aggressive surgical procedures. We performed a randomized phase III trial of postoperative radiochemotherapy in those at moderate risk of locoregional failure (LRF) following surgery. We originally reported results with 4-year median follow-up. This update, with a more than 10-year median follow-up, presents data on failure patterns and second malignancies and explores selected subset analyses. PATIENTS AND METHODS In all, 559 patients with primaries ≥ T3 and/or node-positive gastric cancer were randomly assigned to observation versus radiochemotherapy after R0 resection. Fluorouracil and leucovorin were administered before, during, and after radiotherapy. Radiotherapy was given to all LRF sites to a dose of 45 Gy. RESULTS Overall survival (OS) and relapse-free survival (RFS) data demonstrate continued strong benefit from postoperative radiochemotherapy. The hazard ratio (HR) for OS is 1.32 (95% CI, 1.10 to 1.60; P = .0046). The HR for RFS is 1.51 (95% CI, 1.25 to 1.83; P < .001). Adjuvant radiochemotherapy produced substantial reduction in both overall relapse and locoregional relapse. Second malignancies were observed in 21 patients with radiotherapy versus eight with observation (P = .21). Subset analyses show robust treatment benefit in most subsets, with the exception of patients with diffuse histology who exhibited minimal nonsignificant treatment effect. CONCLUSION Intergroup 0116 (INT-0116) demonstrates strong persistent benefit from adjuvant radiochemotherapy. Toxicities, including second malignancies, appear acceptable, given the magnitude of RFS and OS improvement. LRF reduction may account for the majority of overall relapse reduction. Adjuvant radiochemotherapy remains a rational standard therapy for curatively resected gastric cancer with primaries T3 or greater and/or positive nodes.

Phase II trial of neoadjuvant/adjuvant imatinib mesylate (IM) for advanced primary and metastatic/recurrent operable gastrointestinal stromal tumor (GIST): early results of RTOG 0132/ACRIN 6665.

Therapy for gastrointestinal stromal tumors (GIST) has changed significantly with the use of imatinib mesylate (IM). Despite the success of this drug in metastatic GIST, disease progression remains a perplexing clinical issue suggesting the need for multimodality management. There have been no prospective studies either evaluating the neoadjuvant use of IM in primary GIST or as a preoperative cytoreduction agent for metastatic GIST.

Phase II Trial of Erlotinib in Gastroesophageal Junction and Gastric Adenocarcinomas: SWOG 0127

PURPOSE A phase II trial of the oral epidermal growth factor receptor (EGFR) inhibitor erlotinib in patients with gastroesophageal adenocarcinomas stratified according to primary tumor location into two groups: gastroesophageal junction (GEJ)/cardia and distal gastric adenocarcinomas. PATIENTS AND METHODS Patients with a histologically proven diagnosis of adenocarcinoma of the GEJ or stomach (ST) that was unresectable or metastatic; presence of measurable disease; no prior chemotherapy for advanced or metastatic cancer; Zubrod performance status (PS) of 0 to 1; and adequate renal, hepatic, and hematologic function were treated with erlotinib 150 mg/d orally. Patient characteristics were median age, GEJ-63 years, ST-64 years; sex, GEJ-84% male and 16% female, ST-60 male and 40 female; Zubrod PS, GEJ-25 had a PS of 0 and 18 had a PS 1, ST-13 had a PS of 0 and 12 had a PS of 1. RESULTS Percentage of common toxicities were skin rash, 86% and 72%; fatigue, 51% and 44%; and AST/ALT elevation, 28% and 28%, respectively for GEJ and ST. There has been one confirmed complete response, three confirmed partial responses (PRs) and one unconfirmed PR for an overall response probability of 9% confirmed (95% CI, 3% to 22%), all occurring in GEJ stratum. No responses were observed in ST stratum. The median survival was 6.7 months in GEJ and 3.5 months in ST stratum. Neither intratumoral EGFR, transforming growth factor-alpha or phosphorylated Akt kinase expression nor plasma proteomic analyses were predictive of clinical outcome. No somatic mutations of the EGFR exons 18, 19, or 21 were detected and there was no gross amplification of EGFR by fluorescence in situ hybridization. CONCLUSION Erlotinib is active in patients with GEJ adenocarcinomas, but appears inactive in gastric cancers. The molecular correlates examined were not predictive of the patient therapeutic response.

Southwest Oncology Group study S0413: a phase II trial of lapatinib (GW572016) as first-line therapy in patients with advanced or metastatic gastric cancer

Background: Lapatinib (GW572016) is a dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2/ErbB2), which are reported as overexpressed in 15%–45% of gastric cancers, making them potential targets. Patients and methods: The primary objective of this study was to assess response rate. Secondary objectives included overall survival (OS), toxicity, and the relationship of EGFR, ErbB2, and markers of angiogenesis with clinical outcome. Lapatinib was administered to chemonaive metastatic gastric cancer patients at a dose of 1500 mg orally daily for 28 days. Results: The study enrolled 47 patients from February 2005 until May 2006. Four patients (9%) had a confirmed partial response (PR), 1 (2%) had an unconfirmed PR, and 10 (23%) had stable disease. Median (95% confidence interval) time to treatment failure was 1.9 (1.6–3.1) months and OS was 4.8 (3.2–7.4) months. Significant adverse events: one grade 4 cardiac ischemia/infarction, one grade 4 fatigue, and one grade 4 emesis. One treatment-related death was due to central nervous system ischemia. An exploratory analysis of markers revealed gene expression of HER2, interleukin (IL)-8 and genomic polymorphisms IL-8, and vascular endothelial growth factor correlated with OS. Conclusions: Lapatinib is well tolerated, with modest single-agent activity in advanced/metastatic gastric cancer patients. Potential molecular correlatives were identified which warrant further validation.

Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are mesenchymal gut tumors that differ dramatically from other histologically similar neoplasms, such as leimomyomas, leiomyosarcomas (LMS), and neural tumors. Complete surgical removal remains the best current therapy for GISTs, but even major resections are associated with recurrence in approximately 90% of cases. GISTs are remarkably resistant to irradiation and standard chemotherapy; there is no role for treatment with those modalities. Treatment of advanced GIST patients with STI571, a novel selective tyrosine kinase inhibitor, results in remission rates that approach 60% and overall tumor control rates of 85%. Selected groups of patients, as based on tumor mutational status, have response rates as high as 80%. To date, STI571 therapy remains the only systemic treatment for GISTs to have meaningful clinical activity. Though other molecularly targeted therapies exist in oncology (eg, trastuzumab), STI571 is one of the first that applies a drug specifically designed to inhibit the product of a constitutively-activating mutation that drives pathogenesis of a solid tumor. Its use can serve as a paradigm for designing molecularly targeted therapies for other malignancies.

Microscopically Positive Margins for Primary Gastrointestinal Stromal Tumors: Analysis of Risk Factors and Tumor Recurrence

BACKGROUND Little is known about the outcomes of patients with microscopically positive (R1) resections for primary gastrointestinal stromal tumors (GIST) because existing retrospective series contain small numbers of patients. The objective of this study was to analyze factors associated with R1 resection and assess the risk of recurrence with and without imatinib. STUDY DESIGN We reviewed operative and pathology reports for 819 patients undergoing resection of primary GIST from the North American branch of the American College of Surgeons Oncology Group (ACOSOG) Z9000 and Z9001 clinical trials at 230 institutions testing adjuvant imatinib after resection of primary GIST. Patient, tumor, operative characteristics, factors associated with R1 resections, and disease status were analyzed. RESULTS Seventy-two (8.8%) patients had an R1 resection and were followed for a median of 49 months. Factors associated with R1 resection included tumor size (≥ 10 cm), location (rectum), and tumor rupture. The risk of disease recurrence in R1 patients was driven largely by the presence of tumor rupture. There was no significant difference in recurrence-free survival for patients undergoing an R1 vs R0 resection of GIST with (hazard ratio [HR] 1.095, 95% CI 0.66, 1.82, p = 0.73) or without (HR 1.51, 95% CI 0.76, 2.99, p = 0.24) adjuvant imatinib. CONCLUSIONS Approximately 9% of 819 GIST patients had an R1 resection. Significant factors associated with R1 resection include tumor size ≥ 10 cm, location, and rupture. The difference in recurrence-free survival with or without imatinib therapy in those undergoing an R1 vs R0 resection was not statistically significant at a median follow-up of 4 years.

Cetuximab as Second-Line Therapy in Patients with Metastatic Esophageal Adenocarcinoma: A Phase II Southwest Oncology Group Study (S0415)

Introduction: Esophageal adenocarcinomas commonly express the epidermal growth factor receptor. This trial assessed the 6-month overall survival probability in metastatic esophageal cancer patients treated with cetuximab as second-line therapy. Methods: This was a multicenter, open-label phase II study of single-agent cetuximab for metastatic esophageal adenocarcinoma patients who failed one prior chemotherapy regimen. Adequate organ function and Zubrod performance status of 0 to 2 were required. Patients received cetuximab 400 mg/m2 intravenously (IV) on week 1 and 250 mg/m2 IV weekly thereafter. The primary objective was to determine 6-month overall survival. Secondary end points included progression-free survival, response rate, and toxicity. Tumor tissue was collected for correlative studies. Results: Sixty-three patients were registered, with eight ineligible or never treated. Fifty-five eligible patients (49 men, 6 women; median age = 61.2 years [range, 30.7–88.5]) were enrolled. Twenty patients survived more than 6 months for a 6-month overall survival rate of 36% (95% confidence interval [CI]: 24–50%). The median overall survival was 4.0 months (95% CI: 3.2–5.9). Median progression-free survival was 1.8 months (95% CI: 1.7–1.9). One partial response and two unconfirmed partial responses were observed. Two patients experienced grade 4 fatigue. There was one treatment-related death due to pneumonitis. Germline polymorphisms of epidermal growth factor receptor, epidermal growth factor, interleukin (IL)-8, cyclooxygenase (COX)-2, vascular epidermal growth factor receptor (VEGF), CCND1, neuropilin 1 (NRP1), and K-ras mutational status were not associated with response or survival. Conclusions: The 6-month overall survival rate of 36% observed on this study failed to meet the primary survival objective. Thus, cetuximab alone cannot be recommended in the second-line treatment of metastatic esophageal cancer.

Dual blockade of epidermal growth factor receptor and insulin-like growth factor receptor–1 signaling in metastatic pancreatic cancer: Phase Ib and randomized phase II trial of gemcitabine, erlotinib, and cixutumumab versus gemcitabine plus erlotinib (SWOG S0727)

Targeting a single pathway in pancreatic adenocarcinoma (PC) is unlikely to affect its natural history. We tested the hypothesis that simulataneous targeting of the epidermal growth factor receptor (EGFR) and insulin‐like growth factor receptor–1 (IGF‐1R) pathways would significantly improve progression‐free survival (PFS) by abrogating reciprocal signaling that promote drug resistance

Gene expression signatures and response to imatinib mesylate in gastrointestinal stromal tumor

Despite initial efficacy of imatinib mesylate in most gastrointestinal stromal tumor (GIST) patients, many experience primary/secondary drug resistance. Therefore, clinical management of GIST may benefit from further molecular characterization of tumors before and after imatinib mesylate treatment. As part of a recent phase II trial of neoadjuvant/adjuvant imatinib mesylate treatment for advanced primary and recurrent operable GISTs (Radiation Therapy Oncology Group S0132), gene expression profiling using oligonucleotide microarrays was done on tumor samples obtained before and after imatinib mesylate therapy. Patients were classified according to changes in tumor size after treatment based on computed tomography scan measurements. Gene profiling data were evaluated with Statistical Analysis of Microarrays to identify differentially expressed genes (in pretreatment GIST samples). Based on Statistical Analysis of Microarrays [False Discovery Rate (FDR), 10%], 38 genes were expressed at significantly lower levels in the pretreatment biopsy samples from tumors that significantly responded to 8 to 12 weeks of imatinib mesylate, that is, >25% tumor reduction. Eighteen of these genes encoded Krüppel-associated box (KRAB) domain containing zinc finger (ZNF) transcriptional repressors. Importantly, 10 KRAB-ZNF genes mapped to a single locus on chromosome 19p, and a subset predicted likely response to imatinib mesylate–based therapy in a naïve panel of GIST. Furthermore, we found that modifying expression of genes within this predictive signature can enhance the sensitivity of GIST cells to imatinib mesylate. Using clinical pretreatment biopsy samples from a prospective neoadjuvant phase II trial, we have identified a gene signature that includes KRAB-ZNF 91 subfamily members that may be both predictive of and functionally associated with likely response to short-term imatinib mesylate treatment. [Mol Cancer Ther 2009;8(8):2172–82]