Imatinib plasma levels in patients with gastrointestinal stromal tumour under routine clinical practice conditions.

OBJECTIVES: Imatinib is the first therapeutic option for the treatment of unresectable or metastatic gastrointestinal stromal tumours. Previous studies have shown an improvement in patient survival rates following the use of imatinib. Nevertheless, adequate plasma concentrations of imatinib are necessary to achieve such improvement in survival and limit the toxicity of the drug. This study aims to analyse the influence of imatinib plasma concentrations on efficacy and safety in the treatment of gastrointestinal stromal tumour. MATERIALS AND METHODS: This descriptive, multicentre study analysed plasma levels of imatinib in patients diagnosed with gastrointestinal stromal tumour in the period 2019-2020. An optimal therapeutic range of 750-1500 ng/mL was established for the patient stratification based on their minimum plasma concentrations measured at the steady state. RESULTS: This study included 11 patients with metastatic disease in total, among whom only 54.5% (n = 6) had a minimum plasma concentrations measured at the steady state value within the therapeutic range. A median progression-free survival of 7.0 months was recorded for those patients with minimum plasma concentrations measured at the steady state < 750 ng/mL, while that median progression-free survival value remained unachieved for the group with minimum plasma concentrations measured at the steady state > 750 ng/mL (p = 0.005). The toxicity rate was 25% and 14.3% for patients with minimum plasma concentrations measured at the steady state > 1500 ng/mL and minimum plasma concentrations measured at the steady state ≤1500 ng/mL, respectively (p = 0.66). CONCLUSIONS: The present study aims to describe the correlation between the toxicity and effectiveness of imatinib as a function of minimum plasma concentrations measured at the steady state under routine clinical practice conditions. The results described here show the usefulness of imatinib plasma concentrations monitoring as part of the standard daily routine in our hospitals.

High-risk soft tissue sarcomas treated with perioperative chemotherapy: Improving prognostic classification in a randomised clinical trial.

BACKGROUND: Patients with extremity and trunk wall soft tissue sarcoma (STS) with high malignancy grade and size >5 cm are at high-risk of death. This risk varies depending also on other patient and tumour features, including histologic subtype. This study investigated whether a prognostic nomogram can improve risk assessment of these patients. METHODS: Data from high-risk STS patients enrolled in a randomised controlled trial investigating different perioperative chemotherapy regimens were analysed. Ten-year probability of overall survival (OS) and incidence of distant metastasis (DM) were computed using the prognostic nomogram Sarculator (pr-OS and inc-DM, respectively). Tumour response according to RECIST and Choi criteria was also investigated. FINDINGS: Variation in pr-OS and inc-DM were observed and patients stratified in three prognostic groups. The 10-year OS in the low, intermediate, and high pr-OS categories were 0·42 (95%CI 0·32-0·52), 0·63 (95%CI 0·53-0·72), and 0·78 (95%CI 0·68-0·85), respectively. Patients in the intermediate (HR 0·51, P = 0·002) and high (HR 0·28, P < 0·001) pr-OS categories were at statistically significant lower risk of death compared with those in the low pr-OS category. Higher rate of Choi partial tumour responses were detected in intermediate pr-OS category. Tumour response according to Choi but not to RECIST criteria stratified patient survival of pr-OS categories, particularly for patients with intermediate to low pr-OS. Analyses conducted for 10-year inc-DM were consistent with results for pr-OS for prognostic value of Sarculator predictions and Choi tumour response. INTERPRETATION: Sarculator identifies variations in outcomes of high-risk STS treated with perioperative chemotherapy and improve prognostic classification, which is also associated with different patterns of tumour response, an outcome that further stratifies survival particularly for patients predicted at higher risk. Future trials investigating neoadjuvant chemotherapy should consider prognostic tool for selecting patients to be enrolled. TRIAL REGISTRATION NUMBER: European Union Drug Regulating Authorities Clinical Trials No. 2004-003979-36.