Michael Montemurro

Early Prediction of Response to Sunitinib After Imatinib Failure by 18F-Fluorodeoxyglucose Positron Emission Tomography in Patients With Gastrointestinal Stromal Tumor

PURPOSE Positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) was used to evaluate treatment response in patients with gastrointestinal stromal tumors (GIST) after administration of sunitinib, a multitargeted tyrosine kinase inhibitor, after imatinib failure. PATIENTS AND METHODS Tumor metabolism was assessed with FDG-PET before and after the first 4 weeks of sunitinib therapy in 23 patients who received one to 12 cycles of sunitinib therapy (4 weeks of 50 mg/d, 2 weeks off). Treatment response was expressed as the percent change in maximal standardized uptake values (SUV). The primary end point of time to tumor progression was compared with early PET results on the basis of traditional Response Evaluation Criteria in Solid Tumors (RECIST) criteria. RESULTS Progression-free survival (PFS) was correlated with early FDG-PET metabolic response (P < .0001). Using -25% and +25% thresholds for SUV variations from baseline, early FDG-PET response was stratified in metabolic partial response, metabolically stable disease, or metabolically progressive disease; median PFS rates were 29, 16, and 4 weeks, respectively. Similarly, when a single FDG-PET positive/negative was considered after 4 weeks of sunitinib, the median PFS was 29 weeks for SUVs less than 8 g/mL versus 4 weeks for SUVs of 8 g/mL or greater (P < .0001). None of the patients with metabolically progressive disease subsequently responded according to RECIST criteria. Multivariate analysis showed shorter PFS in patients who had higher residual SUVs (P < .0001), primary resistance to imatinib (P = .024), or nongastric GIST (P = .002), regardless of the mutational status of the KIT and PDGFRA genes. CONCLUSION Week 4 FDG-PET is useful for early assessment of treatment response and for the prediction of clinical outcome. Thus, it offers opportunities to individualize and optimize patient therapy.

Drug interactions with the tyrosine kinase inhibitors imatinib, dasatinib, and nilotinib

Several cancer treatments are shifting from traditional, time-limited, nonspecific cytotoxic chemotherapy cycles to continuous oral treatment with specific protein-targeted therapies. In this line, imatinib mesylate, a selective tyrosine kinases inhibitor (TKI), has excellent efficacy in the treatment of chronic myeloid leukemia. It has opened the way to the development of additional TKIs against chronic myeloid leukemia, including nilotinib and dasatinib. TKIs are prescribed for prolonged periods, often in patients with comorbidities. Therefore, they are regularly co-administered along with treatments at risk of drug-drug interactions. This aspect has been partially addressed so far, calling for a comprehensive review of the published data. We review here the available evidence and pharmacologic mechanisms of interactions between imatinib, dasatinib, and nilotinib and widely prescribed co-medications, including known inhibitors or inducers of cytochromes P450 or drug transporters. Information is mostly available for imatinib mesylate, well introduced in clinical practice. Several pharmacokinetic aspects yet remain insufficiently investigated for these drugs. Regular updates will be mandatory and so is the prospective reporting of unexpected clinical observations.

Cetuximab in Combination With Chemoradiotherapy Before Surgery in Patients With Resectable, Locally Advanced Esophageal Carcinoma : a Prospective, Multicenter Phase IB/II Trial (SAKK 75/06)

PURPOSE This multicenter phase IB/II trial investigated cetuximab added to preoperative chemoradiotherapy for esophageal cancer. PATIENTS AND METHODS Patients with resectable, locally advanced esophageal cancer received two 3-week cycles of induction chemoimmunotherapy (cisplatin 75 mg/m(2) day 1, docetaxel 75 mg/m(2) day 1, cetuximab 250 mg/m(2) days 1, 8,15 [400 mg/m(2) loading dose]) followed by chemoimmunoradiation therapy (CIRT) and surgery. CIRT consisted of 45 Gy radiotherapy (RT) plus concurrent cisplatin 25 mg/m(2) and cetuximab 250 mg/m(2) weekly for 5 weeks in cohort 1. If fewer than three of seven patients experienced limiting toxicity (LT), the next seven patients also received docetaxel (20 mg/m(2) weekly × 5). If fewer than three patients experienced LTs, 13 additional patients were treated at this dose. RESULTS In total, 28 patients (median age, 64 years) with predominantly node-positive (82%) esophageal adenocarcinoma (15 patients) or squamous cell carcinoma (13 patients) were enrolled and 24 (86%) completed the entire trimodal therapy. During CIRT, no LT occurred, rash was not exacerbated within the RT field, and the main grade 3 toxicities were esophagitis (seven patients), anorexia (three), fatigue (three), and thrombosis (two). Surgery (R0 resection) was performed in 25 patients. Anastomotic leakage occurred in three patients: two recovered spontaneously and one successfully underwent re-operation. There were no deaths at 30 days and no treatment-related mortality after 12 months. Nineteen patients (68%) showed complete or near complete pathologic regression. CONCLUSION Adding cetuximab to preoperative chemoradiotherapy is feasible without increasing postoperative mortality. Phase III investigation has begun based on the high histopathologic response and R0 resection rate.

Continuous Sunitinib treatment in patients with advanced hepatocellular carcinoma: a Swiss Group for Clinical Cancer Research (SAKK) and Swiss Association for the Study of the Liver (SASL) multicenter phase II trial (SAKK 77/06).

BACKGROUND Sunitinib (SU) is a multitargeted tyrosine kinase inhibitor with antitumor and antiangiogenic activity. The objective of this trial was to demonstrate antitumor activity of continuous SU treatment in patients with hepatocellular carcinoma (HCC). PATIENTS AND METHODS Key eligibility criteria included unresectable or metastatic HCC, no prior systemic anticancer treatment, measurable disease, and Child-Pugh class A or mild Child-Pugh class B liver dysfunction. Patients received 37.5 mg SU daily until progression or unacceptable toxicity. The primary endpoint was progression-free survival at 12 weeks (PFS12). RESULTS Forty-five patients were enrolled. The median age was 63 years; 89% had Child-Pugh class A disease and 47% had distant metastases. PFS12 was rated successful in 15 patients (33%; 95% confidence interval, 20%-47%). Over the whole trial period, one complete response and a 40% rate of stable disease as the best response were achieved. The median PFS duration, disease stabilization duration, time to progression, and overall survival time were 1.5, 2.9, 1.5, and 9.3 months, respectively. Grade 3 and 4 adverse events were infrequent. None of the 33 deaths were considered drug related. CONCLUSION Continuous SU treatment with 37.5 mg daily is feasible and has moderate activity in patients with advanced HCC and mild to moderately impaired liver dysfunction. Under this trial design (>13 PFS12 successes), the therapy is considered promising. This is the first trial describing the clinical effects of continuous dosing of SU in HCC patients on a schedule that is used in an ongoing, randomized, phase III trial in comparison with the current treatment standard, sorafenib (ClinicalTrials.gov identifier, NCT00699374).

Therapeutic Drug Monitoring of Imatinib

BackgroundThe imatinib trough plasma concentration (Cmin) correlates with clinical response in cancer patients. Therapeutic drug monitoring (TDM) of plasma Cmin is therefore suggested. In practice, however, blood sampling for TDM is often not performed at trough. The corresponding measurement is thus only remotely informative about Cmin exposure.ObjectivesThe objectives of this study were to improve the interpretation of randomly measured concentrations by using a Bayesian approach for the prediction of Cmin, incorporating correlation between pharmacokinetic parameters, and to compare the predictive performance of this method with alternative approaches, by comparing predictions with actual measured trough levels, and with predictions obtained by a reference method, respectively.MethodsA Bayesian maximum a posteriori (MAP) estimation method accounting for correlation (MAP-ρ) between pharmacokinetic parameters was developed on the basis of a population pharmacokinetic model, which was validated on external data. Thirty-one paired random and trough levels, observed in gastrointestinal stromal tumour patients, were then used for the evaluation of the Bayesian MAP-ρ method: individual Cmin predictions, derived from single random observations, were compared with actual measured trough levels for assessment of predictive performance (accuracy and precision). The method was also compared with alternative approaches: classical Bayesian MAP estimation assuming uncorrelated pharmacokinetic parameters, linear extrapolation along the typical elimination constant of imatinib, and non-linear mixed-effects modelling (NONMEM) first-order conditional estimation (FOCE) with interaction. Predictions of all methods were finally compared with ‘best-possible’ predictions obtained by a reference method (NONMEM FOCE, using both random and trough observations for individual Cmin prediction).ResultsThe developed Bayesian MAP-ρ method accounting for correlation between pharmacokinetic parameters allowed non-biased prediction of imatinib Cmin with a precision of ±30.7%. This predictive performance was similar for the alternative methods that were applied. The range of relative prediction errors was, however, smallest for the Bayesian MAP-ρ method and largest for the linear extrapolation method. When compared with the reference method, predictive performance was comparable for all methods. The time interval between random and trough sampling did not influence the precision of Bayesian MAP-ρ predictions.ConclusionClinical interpretation of randomly measured imatinib plasma concentrations can be assisted by Bayesian TDM. Classical Bayesian MAP estimation can be applied even without consideration of the correlation between pharmacokinetic parameters. Individual Cmin predictions are expected to vary less through Bayesian TDM than linear extrapolation. Bayesian TDM could be developed in the future for other targeted anticancer drugs and for the prediction of other pharmacokinetic parameters that have been correlated with clinical outcomes.

Diffusion-weighted magnetic resonance imaging in metastatic gastrointestinal stromal tumor (GIST): a pilot study on the assessment of treatment response in comparison with 18F-FDG PET/CT

Background Diffusion-weighted magnetic resonance imaging (MRI) is increasingly being used for assessing the treatment succes in oncology, but the real clinical value needs to evaluated by comparison with other, already established, metabolic imaging techniques. Purpose To prospectively evaluate the clinical potential of diffusion-weighted MRI with apparent diffusion coefficient (ADC) mapping for gastrointestinal stromal tumor (GIST) response to targeted therapy compared with 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). Material and Methods Eight patients (mean age, 56 ± 11 years) known to have metastatic GIST underwent 18F-FDG PET/CT and MRI (T1Gd, DWI [b = 50,300,600], ADC mapping) simultaneously, before and after change in targeted therapy. MR and PET/CT examinations were first analyzed blindly. Second, PET/CT images were co-registered with T1Gd-MR images for lesion detection. Only 18F-FDG avid lesions were considered. Maximum standardized uptake value (SUVmax) and the corresponding minimum ADCmin were measured for the six largest lesions per patient, if any, on baseline and follow-up examinations. The relationship between changes in SUVmax and ADCmin was analyzed (Spearmans correlation). Results Twenty-four metastases (12 hepatic, 12 extra-hepatic) were compared on PET/CT and MR images. SUVmax decreased from 7.7 ± 8.1 g/mL to 5.5 ± 5.4 g/mL (P = 0.20), while ADCmin increased from 1.2 ± 0.3 × 10−3mm2/s to 1.5 ± 0.3 × 10−3mm2/s (P = 0.0002). There was a significant association between changes in SUVmax and ADCmin (rho = − 0.62, P = 0.0014), but not between changes in lesions size (P = 0.40). Conclusion Changes in ADCmin correlated with the response of 18F-FDG avid GIST to targeted therapy. Thus, diffusion-weighted MRI may represent a radiation-free alternative for follow-up treatment for metastatic GIST patients.

Radiotherapy for GIST progressing during or after tyrosine kinase inhibitor therapy: A prospective study

PURPOSE Gastrointestinal stromal tumor (GIST) has been considered radiation-resistant, and radiotherapy is recommended only for palliation of bone metastases in current treatment guidelines. No registered prospective trial has evaluated GIST responsiveness to radiotherapy. PATIENTS AND METHODS Patients with GIST progressing at intra-abdominal sites or the liver were entered to this prospective Phase II multicenter study (identifier NCT00515931). Metastases were treated with external beam radiotherapy using either conformal 3D planning or intensity modulated radiotherapy and conventional fractionation to a cumulative planning target volume dose of approximately 40 Gy. Systemic therapy was maintained unaltered during the study. RESULTS Of the 25 patients entered, 19 were on concomitant tyrosine kinase inhibitor therapy, most often imatinib. Two (8%) patients achieved partial remission, 20 (80%) had stable target lesion size for ⩾3 months after radiotherapy with a median duration of stabilization of 16 months, and 3 (12%) progressed. The median time to radiotherapy target lesion progression was 4-fold longer than the median time to GIST progression at any site (16 versus 4 months). Radiotherapy was generally well tolerated. CONCLUSIONS Responses to radiotherapy were infrequent, but most patients had durable stabilization of the target lesions. GIST patients with soft tissue metastases benefit frequently from radiotherapy.

Prediction of free imatinib concentrations based on total plasma concentrations in patients with gastrointestinal stromal tumours

AIM Total imatinib concentrations are currently measured for the therapeutic drug monitoring of imatinib, whereas only free drug equilibrates with cells for pharmacological action. Due to technical and cost limitations, routine measurement of free concentrations is generally not performed. In this study, free and total imatinib concentrations were measured to establish a model allowing the confident prediction of imatinib free concentrations based on total concentrations and plasma proteins measurements. METHODS One hundred and fifty total and free plasma concentrations of imatinib were measured in 49 patients with gastrointestinal stromal tumours. A population pharmacokinetic model was built up to characterize mean total and free concentrations with inter-patient and intrapatient variability, while taking into account α1 -acid glycoprotein (AGP) and human serum albumin (HSA) concentrations, in addition to other demographic and environmental covariates. RESULTS A one compartment model with first order absorption was used to characterize total and free imatinib concentrations. Only AGP influenced imatinib total clearance. Imatinib free concentrations were best predicted using a non-linear binding model to AGP, with a dissociation constant Kd of 319 ng ml(-1) , assuming a 1:1 molar binding ratio. The addition of HSA in the equation did not improve the prediction of imatinib unbound concentrations. CONCLUSION Although free concentration monitoring is probably more appropriate than total concentrations, it requires an additional ultrafiltration step and sensitive analytical technology, not always available in clinical laboratories. The model proposed might represent a convenient approach to estimate imatinib free concentrations. However, therapeutic ranges for free imatinib concentrations remain to be established before it enters into routine practice.

Mobilization of hemopoietic stem cells with high‐dose methotrexate plus granulocyte–colony‐stimulating factor in patients with primary central nervous system lymphoma

BACKGROUND: High‐dose therapy with autologous stem cell support after standard dose induction is a promising approach for therapy of primary central nervous system lymphoma (PCNSL). High‐dose methotrexate (HD‐MTX) is a standard drug for induction of PCNSL; however, data about the capacity of HD‐MTX plus granulocyte–colony‐stimulating factor (G‐CSF) to mobilize hemopoietic progenitors are lacking.

Badminton, rectal cancer and 25 kg weight gain during chemotherapy.

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