The novel HLA-B*39:93 allele was identified by sequence-based typing in a French family

A novel HLA-B allele, B*39:93, was identified in a French family.

Oedema-based model for diffuse low-grade gliomas: application to clinical cases under radiotherapy

OBJECTIVES

Diffuse low-grade gliomas are characterized by slow growth. Despite appropriate treatment, they change inexorably into more aggressive forms, jeopardizing the patient's life. Optimizing treatments, for example with the use of mathematical modelling, could help to prevent tumour regrowth and anaplastic transformation. Here, we present a model of the effect of radiotherapy on such tumours. Our objective is to explain observed delay of tumour regrowth following radiotherapy and to predict its duration.

MATERIALS AND METHODS

We have used a migration-proliferation model complemented by an equation describing appearance and draining of oedema. The model has been applied to clinical data of tumour radius over time, for a population of 28 patients.

RESULTS

We were able to show that draining of oedema accounts for regrowth delay after radiotherapy and have been able to fit the clinical data in a robust way. The model predicts strong correlation between high proliferation coefficient and low progression-free gain of lifetime, due to radiotherapy among the patients, in agreement with clinical studies. We argue that, with reasonable assumptions, it is possible to predict (precision ~20%) regrowth delay after radiotherapy and the gain of lifetime due to radiotherapy.

CONCLUSIONS

Our oedema-based model provides an early estimation of individual duration of tumour response to radiotherapy and thus, opens the door to the possibility of personalized medicine.

Improving the time-machine: estimating date of birth of grade II gliomas

OBJECTIVES

Here we present a model aiming to provide an estimate of time from tumour genesis, for grade II gliomas. The model is based on a differential equation describing the diffusion-proliferation process. We have applied our model to situations where tumour diameter was shown to increase linearly with time, with characteristic diametric velocity.

MATERIALS AND METHODS

We have performed numerical simulations to analyse data, on patients with grade II gliomas and to extract information concerning time of tumour biological onset, as well as radiology and distribution of model parameters.

RESULTS AND CONCLUSIONS

We show that the estimate of tumour onset obtained from extrapolation using a constant velocity assumption, always underestimates biological tumour age, and that the correction one should add to this estimate is given roughly by 20/v (year), where v is the diametric velocity of expansion of the tumour (expressed in mm/year). Within the assumptions of the model, we have identified two types of tumour: the first corresponds to very slowly growing tumours that appear during adolescence, and the second type corresponds to slowly growing tumours that appear later, during early adulthood. That all these tumours become detectable around a mean patient age of 30 years could be interesting for formulation of strategies for early detection of tumours.

Pharmacokinetic and biological study of erlotinib in children as monotherapy for refractory brain tumors or with radiation for newly diagnosed brain stem gliomas

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Background: This multicenter phase I study was designed to determine the recommended dose (RD) of erlotinib, a small-molecule EGFR TKI, in patients ≤ 21 years as monotherapy or in combination with radiation therapy (RT). Methods: Group 1 included patients with brain tumors refractory to or relapsing after conventional therapy; receiving erlotinib alone. Group 2 included newly diagnosed patients with brain stem gliomas, who received RT (54Gy) and erlotinib. Conventional 3+3 dose escalation was used for Group 1; a continual reassessment method for Group 2. Four dose levels were planned: 75, 100, 125 and 150 mg/m2/day. Results: A total of 51 patients were enrolled (30 in Group 1; 21 in Group 2); 50 received treatment. Median age was 10 and 6 years, respectively. The RD of erlotinib was 125 mg/m2/day as monotherapy or in combination with RT. 203 adverse events in 44 patients were possibly treatment-related; 188 were G1/2; 9 G3, 2 G4, and 4 G5. Dermatologic and neurologic symptoms were most common; intratumoral hemorrhage was noted in 4 patients. In Group 1, 8 patients (27.6%) had stable disease, 2 with 45% tumor regression. In Group 2, 3 patients (14%) had partial response and 8 (38%) were stabilized; median OS was 12 months. Pharmacokinetic data of 46 patients were analyzed; patients’ weight and erlotinib clearance (CL) were significantly correlated. Mean (± SD) apparent CL and volume of distribution for erlotinib were 143.7 mL/h/kg (± 66.3) and 3.5 L/kg (± 3.0), respectively, and were independent of dose level. Mean half-life for erlotinib was 20.4 hours. Biomarker analyses on archived tumor or biopsy tissue prior to study entry for newly diagnosed brain stem glioma found 18/37 tumors tested were EGFR IHC+; 16/37 and 23/36 were pAKT+ and pMAPK+, respectively. High EGFR expression was more common in supratentorial gliomas; PTEN loss was most common in brain stem glioma (15/19) and was not observed in ependymomas. Conclusions: Erlotinib 125 mg/m2/day has an acceptable tolerability profile in pediatric patients with brain tumors, and can be safely combined with RT. Further studies are required to define the efficacy of this treatment approach and to establish the impact of biomarkers on outcomes in pediatric glial tumors.

No significant financial relationships to disclose.

[Surgical resections in functional areas: report of 89 cases]

Surgical resections for intractable epilepsy are generally associated with a high risk of permanent neurological deficit and a poor rate of seizure control. We present a series of 89 patients operated on from 1992 through 2007 for drug-resistant partial epilepsy, in whom surgery was performed in a functional area of the brain: the central (sensorimotor and supplementary motor areas) region in 48 cases, posterior regions (parietal and occipital) in 27, the insula in eight, and the language areas in six. Epilepsy was cryptogenic in 12 patients, and lesion-related in 77: malformation of cortical development in 43, tumor in 17, perinatal cicatrix in 13, vascular lesion in three, and another prenatal lesion in one. Seventy patients underwent stereoelectroencephalographic (SEEG) exploration. The surgical procedure was resective (lesionectomy or SEEG-guided corticectomy) in 83 patients and multiple stereotactic thermocoagulations in six. Ten patients were reoperated because of early seizure recurrence. A postoperative complication was observed in 12 patients. Postoperative deficits were observed in 54 patients (61%) and resolved completely in 29. In 25, a permanent deficit persisted, minor in 19 and moderate to severe in six, which did not correlate with localization or etiology. With a one-year follow-up in 74 patients (mean, 3.6 years), 53 (72%) were in Engel's class I, including 38 (51%) in class IA. Seizure outcome was significantly associated with etiology: 93% of Taylor-type focal cortical dysplasia, whereas only 40% of cryptogenic epilepsies were in class I (p<0.05). This suggests that resective or disconnective surgery for intractable partial epilepsy in functional areas of the brain may be followed by excellent results on seizures and a moderate risk of permanent neurological sequelae.