Neoadjuvant imatinib in locally advanced gastrointestinal stromal tumors

AIM

To study the role of neoadjuvant imatinib mesylate in downsizing tumors in patients with locally advanced nonmetastatic gastrointestinal stromal tumors (GISTs), thus improving the possibility of complete resection.

MATERIALS AND METHODS

We used neoadjuvant imatinib in six patients with locally advanced GISTs, at a dose of 400 mg daily, given orally in all patients for a median period of 3.5 months (range 1-20 months). All patients had a computerized tomography scan (CT scan) once before starting the treatment and a repeat CT scan 1 month after starting imatinib. Some patients had another CT scan done at 3 months. The tumor volume was calculated using the formula V=4/3 pir3.

RESULTS

Following imatinib therapy, the median reduction in the tumor volume was 40% (range 20-50%). Four of the six patients underwent successful complete resection of the tumor following neoadjuvant imatinib for a median period of 2 months, and are disease free after a median follow-up of 10.5 months (range 3-20 months). Two patients in whom the tumors were deemed to be operable after downsizing refused surgery and are continuing imatinib. Imatinib did not produce serious toxicity in any patient.

CONCLUSION

Neoadjuvant imatinib can be used successfully in patients with locally advanced nonmetastatic GISTs to improve the rates of complete resection and reduce the chance of tumor spill. The optimal duration of neoadjuvant treatment needs to be tailored based on response assessment at frequent intervals to identify the ideal window period for surgery.

Dynamic contrast-enhanced ultrasonography (DCE-US): a new tool for the early evaluation of antiangiogenic treatment

Dynamic contrast-enhanced ultrasonography (DCE-US) is a new functional technique enabling a quantitative assessment of solid tumor perfusion using raw linear data. DCE-US allows the calculation of parameters as slope of wash-in or area under the curve (AUC) representing, respectively, blood flow or blood volume. Reduction in tumor vascularization can easily be detected in responders after 1 or 2 weeks and is correlated with progression-free survival and overall survival in renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC). DCE-US is supported by the French National Cancer Institute (INCa), which is currently studying the technique in metastatic breast cancer, melanoma, colon cancer, gastrointestinal stromal tumors and renal cell carcinoma, as well as in primary hepatocellular carcinoma, to establish the optimal perfusion parameters and timing for quantitative anticancer efficacy assessments. Currently 490 patients are included in 20 centers and the preliminary results on 400 patients with 1,096 DCE-US demonstrated that AUC could be a robust parameter to predict response.

Novel approaches to gastrointestinal stromal tumors resistant to imatinib and sunitinib

Gastrointestinal stromal tumors (GIST) are rare tumors of mesenchymal origin that may arise anywhere along the gastrointestinal tract or in the peritoneum. In most cases, GIST harbor mutations of KIT or PDGFRA. Imatinib mesylate (IM), a small-molecule tyrosine kinase inhibitor developed for the treatment of chronic myeloid leukemia, has been shown to be active against these mutations and has significant activity in patients with metastatic GIST. However, resistance to IM emerges after a median of 24 months of treatment. Sunitinib malate (SU) has been approved for the treatment of patients with IM-resistant advanced GIST, but the median progression-free survival in this setting is only 6 months. This article reviews the current knowledge regarding IM and SU resistance in GIST, as well as the available options for the management of GIST resistant to IM and SU.

Phase I combination study of trabectedin and doxorubicin in patients with soft-tissue sarcoma

PURPOSE

To determine the dose of trabectedin plus doxorubicin with granulocyte colony-stimulating factor support associated with manageable neutropenia and acceptable dose-limiting toxicities (DLT) in patients with recurrent or persistent soft-tissue sarcoma.

METHODS

In this phase I, open-label, multicenter trial, patients previously treated with 0-1 prior chemotherapy regimens excluding doxorubicin, an Eastern Cooperative Oncology Group performance status 0-1, and adequate organ function received a 10- to 15-min i.v. infusion of doxorubicin 60 mg/m(2) immediately followed by a 3-h i.v. infusion of trabectedin 0.9 to 1.3 mg/m(2) on day 1 of a 3-week cycle. Because four of the first six patients experienced DLT-defining neutropenia during cycle 1, all subsequent patients received primary prophylactic granulocyte colony-stimulating factor. The maximum tolerated dose was the highest dose level with six or more patients in which less than one-third of the patients experienced severe neutropenia or DLT. Blood was collected during cycle 1 for pharmacokinetic analyses. Adverse events, tumor response, and survival were assessed.

RESULTS

Patients (N = 41) received a median of six cycles of treatment (range, 2-13). The maximum tolerated dose was trabectedin 1.1 mg/m(2) and doxorubicin 60 mg/m(2). Common grade 3/4 treatment-emergent adverse events were neutropenia (71%), alanine aminotransferase increase (46%), and thrombocytopenia (37%). Overall, 5 (12%) patients achieved a partial response and 34 (83%) maintained stable disease. Median progression-free survival was 9.2 months. Doxorubicin and trabectedin pharmacokinetics were not altered substantially with concomitant administration.

CONCLUSION

The combination of doxorubicin 60 mg/m(2) followed by trabectedin 1.1 mg/m(2) every 21 days is safe and active in patients with soft-tissue sarcoma.

[Evaluation of early response to antiangiogenic treatment with dynamic contrast enhanced ultrasound]

Early functional imaging evaluation of targeted treatments in oncology is of major importance. Dynamic contrast enhanced US is now recognized as a functional imaging technique able to evaluate new antiangiogenic drugs targeting superficial and deep seated lesions. This evaluation is based on an analysis of the curve of signal intensity over time after injection of the contrast agent. The availability of quantification software allows objective quantification of tumor perfusion parameters from linear raw data, prior to logarithmic signal compression, including maximum intensity of enhancement, mean transit time, time to peak, and wash-in slope coefficient. Dynamic contrast enhanced US, a sensitive, reproducible and readily available technique, allows early prediction of tumor response to treatment based on changes in vascularity, before morphological changes (RECIST) become apparent.

Adult human sarcomas. II. Medical oncology

Human sarcoma cells can be killed by radio- and chemotherapy, but tumor cells acquiring resistance frequently kill the patient. A keen understanding of the intracellular course of oncogenic cascades leads to the discovery of small molecular inhibitors of the involved phosphorylated kinases. Targeted therapy complements chemotherapy. Oncogene silencing is feasible by small interfering RNA. The restoration of some of the mutated or deleted tumor-suppressor genes (p53, Rb, PTEN, hSNF, INK/ARF and WT) by demethylation or reacetylation of their histones has been accomplished. Genetically engineered or naturally oncolytic viruses selectively lyse tumors and leave healthy tissues intact. Adeno- or retroviral vectors deliver genes of immunological costimulators, tumor antigens, chemo- or cytokines and/or tumor-suppressor proteins into tumor (sarcoma) cells. Suicide gene delivery results in apoptosis induction. Genes of enzymes that target prodrugs as their substrates render tumor cells highly susceptible to chemotherapy, with the prodrug to be targeted intracellularly. It will be combinations of sophisticated surgical removal of the nonencapsulated and locally invasive primary sarcomas, advanced forms of radiotherapy to the involved sites and immunotherapy with sarcoma vaccines that will cure primary sarcomas. Adoptive immunotherapy with immune lymphocytes will be operational in metastatic disease only when populations of regulatory T cells are controlled. Targeted therapy with small molecular inhibitors of oncogene cascades, the driving forces of sarcoma cells, alteration of the tumor stroma from a supportive to a tumor-hostile environment, reactivation or replacement of wild-type tumor-suppressor genes, and radio-chemotherapy (with much reduced toxicity) will eventually accomplish the cure of metastatic sarcomas.