Is there a role for discontinuing imatinib in patients with advanced gastrointestinal stromal tumour?

Discontinuation versus continuation of imatinib in patients with advanced gastrointestinal stromal tumours (BFR14): exploratory long-term follow-up of an open-label, multicentre, randomised, phase 3 trial

BACKGROUND

The long-term impact of tyrosine kinase inhibitor (TKI) discontinuation on resistance and survival in patients with advanced gastrointestinal stromal tumours (GIST) is unclear. We report the exploratory long-term outcomes of patients with advanced GIST stopping imatinib in the BFR14 trial.

METHODS

BFR14, an open-label, randomised, phase 3 trial, was done in 17 comprehensive cancer centres or hospitals across France. Patients with advanced GIST aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0-3, no previous treatment with imatinib, and no previous malignancy were eligible. Patients were treated with oral imatinib 400 mg daily. Patients with a complete or partial response, or stable disease, according to Response Evaluation Criteria in Solid Tumours (1.0) at 1 year, 3 years, and 5 years from the start of treatment were randomly assigned (1:1) to treatment discontinuation until progression (interruption group) or treatment continuation until progression (continuation group). Randomisation was done centrally with computer-generated permuted blocks of two and six patients stratified by participating centre and presence or absence of residual disease on CT scan. The primary endpoint was progression-free survival. Secondary endpoints included time to imatinib resistance and overall survival. Analyses were conducted on an intention-to-treat basis in all randomly assigned patients who were not lost to follow-up. This trial is registered with ClinicalTrial.gov, NCT00367861.

FINDINGS

Between May 12, 2003, and March 16, 2004, after 1 year of imatinib, 32 patients were randomly assigned to the interruption group and 26 to the continuation group. Between June 13, 2005, and May 30, 2007, after 3 years of imatinib, 25 patients were randomly assigned to the interruption group and 25 to the continuation group. Between Nov 9, 2007, and July 12, 2010, after 5 years of imatinib, 14 patients were randomly assigned to the interruption group and 13 to the continuation group. Median follow-up was 235·2 months (IQR 128·8-236·6) after the 1-year randomisation, 200·9 months (190·2-208·4) after the 3-year randomisation, and 164·5 months (134·4-176·4) after the 5-year randomisation. Median progression-free survival in the interruption group versus the continuation group after 1 year of imatinib was 6·1 months (95% CI 2·5-10·1) versus 27·8 months (19·5-37·9; hazard ratio [HR] 0·36 [95% CI 0·20-0·64], log-rank p=0·0003), after 3 years of imatinib was 7·0 months (3·5-11·7) versus 67·0 months (48·8-85·6; 0·15 [0·07-0·32], log-rank p<0·0001), and after 5 years of imatinib was 12·0 months (9·0-16·6) versus not reached (NR; NR-NR; 0·13 [0·03-0·58], log-rank p=0·0016). The median time to imatinib resistance after 1 year of imatinib was 28·7 months (95% CI 18·1-39·1) versus 90·6 months (25·3-156·1; HR 0·93 [95% CI 0·51-1·71], log-rank p=0·82), after 3 years was 66·2 months (43·0-89·6) versus 127·3 months (15·0-239·7; 0·35 [0·17-0·72, log-rank p=0·0028), and after 5 years was 58·6 months (0·0-167·4) versus NR (NR-NR; 0·24 [0·05-1·12], log-rank p=0·049). Median overall survival after 1 year of imatinib was 56·0 months (95% CI 30·3-82·9) versus 105·0 months (20·6-189·6; HR 0·84 [95% CI 0·46-1·54], log-rank p=0·57), after 3 years was 104·0 months (90·7-118·7) versus 134·0 months (89·7-178·3; 0·40 [0·20-0·82], log-rank p=0·0096), and after 5 years was NR (NR-NR) versus 110·4 months (82·7-154·1; 1·28 [0·41-3·99]; log-rank p=0·67), INTERPRETATION: Imatinib interruption in patients with GIST without progressive disease is not recommended. Imatinib interruption in non-progressing patients with GIST was associated with rapid progression, faster resistance to imatinib, and shorter overall survival in the long-term follow-up when compared with imatinib continuation in patients after 3 years and 5 years of imatinib.

FUNDING

Centre Léon Bérard, INCa, CONTICANET, Ligue Contre le Cancer, and Novartis.

Case report: 10-year survival of a patient with a primary hepatic gastrointestinal stromal tumor

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract. Extra-gastrointestinal stromal tumors (EGISTs) predominantly arise outside the gastrointestinal tract, although primary hepatic GISTs are extremely rare. GISTs are highly aggressive; they often grow to a large size. Here, we report the 10-year survival of a patient with a primary hepatic GIST following sequential response therapy.

CASE PRESENTATION

A 50-year-old Chinese man complained of fatigue and slight abdominal pain, and presented with a large lump in the liver, which was detected by computed tomography (CT). He was subsequently diagnosed with a primary hepatic GIST, based on CT-guided fine needle aspiration cytology and immunohistochemistry analyses. The presence of GIST or EGIST metastases was excluded using CT, esophagogastroduodenoscopy, colonoscopy, and ultrasound. Cytological examination showed that the tumor was composed of epithelioid and spindle cells. Immunohistochemistry analysis revealed positive staining for CD117 (KIT) and DOG1, and negative staining for CD34, S-100, and α-smooth muscle actin (SMA). Following tumor ablation with argon-helium cryosurgery, the patient received imatinib mesylate for 61 months. However, this treatment was discontinued because of disease progression, at which point interventional therapy was administered once. One month later, sunitinib malate was administered for 71 months. The patient achieved long-term survival for 135 months.

CONCLUSIONS

EGISTs can be easily misdiagnosed as other types of tumors because they have no specific characteristics to distinguish them during imaging examinations. However, our case study demonstrates that the long-term survival of patients with EGISTs can be achieved with molecular targeted therapy.

Imatinib rechallenge in patients with advanced gastrointestinal stromal tumors

BACKGROUND

Imatinib is the standard of care for patients with advanced gastrointestinal stromal tumors (GIST).

DESIGN

This article reviews recent data on the impact of imatinib treatment interruption and subsequent rechallenge in patients with advanced GIST.

RESULTS

The randomized BFR14 trial showed that (i) interruption of imatinib after 1, 3, or 5 years of treatment in patients with nonprogressive GIST was associated with a high risk of progression even in patients with a complete response; (ii) rechallenge with imatinib restored tumor control in most patients, but the tumor response seldom reached that before treatment interruption; (iii) patients receiving continuous imatinib had a high rate of prolonged tumor control, which increased with longer imatinib treatment. The findings in the metastatic setting have important implications regarding the duration of adjuvant imatinib in GIST.

CONCLUSIONS

Discontinuation of imatinib in responding patients with advanced GIST is associated with a high risk of progression and is therefore not recommended. Although rechallenge is a strategy for treating patients who relapse after stopping imatinib, suboptimal tumor response indicates that continuous kinase suppression is necessary to achieve the best clinical outcome. Three-year adjuvant imatinib is recommended for patients with resected 'high-risk' GIST; however, a longer duration may provide additional benefits.

[KIT and KIT: from biology to clinical use]

Scientific knowledge on gastrointestinal stromal tumors (GIST) has highly progressed over the last 10 years. The molecular bases of oncogenic transformation, KIT activating mutations, were identified in 1998 by Hirota et al. The product of KIT proto-oncogene, KIT protein, is a transmembrane receptor with tyrosine kinase activity. Tyrosine kinase inhibitors targeting these mutated activated kinases, namely imatinib and more recently sunitinib, nilotinib, masitinib or sorafenib, have deeply modified GIST prognosis. Molecular biology in GIST is now becoming a routine tool for treatment selection. In patients with advanced GIST, imatinib should be given until progression, and then, other tyrosine kinase inhibitors targeting KIT should be used. In the adjuvant setting, the optimal duration of imatinib treatment remains unknown.

Surveillance strategies for gastrointestinal stromal tumors

Although only 10-30% of gastrointestinal stromal tumors (GISTs) are clinically malignant, all have some degree of malignant potential. The management of high risk patients should be evidence based. However, prospective data and a consensus for guidelines concerning the screening of asymptomatic high risk patients and surveillance following multidisciplinary treatment do not exist. This review provides an overview of GIST, with an emphasis on the available data regarding screening and surveillance of certain populations with GISTs.

Adjuvant imatinib for gastrointestinal stromal tumors: the current situation and problems

OBJECTIVE

To review the current situation and find out the current problems of adjuvant imatinib for gastrointestinal stromal tumors (GISTs).

METHODS

Searching for articles and records about imatinib for GISTs, especially adjuvant imatinib for GISTs, on MEDLINE, EMBASE and international conference on gastrointestinal.

RESULTS

GISTs are derived from mesenchymal cells of the gastrointestinal tract. The standard treatment for primary GISTs is to resect the tumor together with the negative margins completely without tumor rupture and spillage. Conventional chemotherapy and radiotherapy is ineffective for advanced GISTs. The introduction of imatinib has dramatically changed the natural history of advanced GISTs. Imatinib is generally safe and effective with doses of 400, 600 or 800 mg daily, and has become the standard drug in the treatment for patients with advanced GISTs. Furthermore, most of the toxicity of imatinib is minimal and manageable, almost no treatment-related deaths have been reported. Therefore, adjuvant imatinib therapy is safe and seems to improve recurrence-free survival after the resection of primary GISTs.

CONCLUSIONS

Although U.S Food and Drug Administration and European Medicines Agency have approved the use of adjuvant imatinib for GISTs postoperatively, a series of questions about the use of adjuvant imatinib still exist, such as the impact of adjuvant imatinib on overall survival, the optimal dose, the best duration of treatment and the most suitable patients. Doctors and patients should weigh the pros (the decrease of relapse) and cons (drug toxicity and drug costs), especially in terms of the benefit of overall survival.

Added value of molecular targeted agents in oncology

The treatment of certain cancers has been revolutionised in recent years by the introduction of novel drugs designed to target specific molecular factors implicated in tumour growth. Notable examples include trastuzumab, a humanized monoclonal antibody (mAb) against human epidermal growth factor receptor (HER)-2 in women with HER2-positive breast cancer; rituximab, an anti-CD20 mAb in patients with non-Hodgkin's lymphoma; imatinib, a tyrosine kinase inhibitor in KIT-positive gastrointestinal stromal tumours and sunitinib, another tyrosine kinase inhibitor, in metastatic renal cell carcinoma. For regulatory reasons, new molecular targeted agents are first evaluated in advanced and metastatic disease, wherein they prolong survival. However, their most profound impact has been observed in the adjuvant setting, where they may contribute to curative therapy rather than mere palliation. Expansion in the use of molecular targeted therapies will have important cost implications for health care systems. Although expensive, on a monthly basis, molecular targeted therapies may not be more costly than treatments for other major chronic diseases, especially considering the contribution of cancer to the global disease burden, the associated socioeconomic costs and the long-term benefits of therapy. Nevertheless, the use of these agents must be optimised, in part using molecular biomarkers associated with drug response.