Brain tumors

Promising survival for patients with newly diagnosed glioblastoma multiforme treated with concomitant radiation plus temozolomide followed by adjuvant temozolomide

PURPOSE

Temozolomide is a novel oral alkylating agent with demonstrated efficacy as second-line therapy for patients with recurrent anaplastic astrocytoma and glioblastoma multiforme (GBM). This phase II study was performed to determine the safety, tolerability, and efficacy of concomitant radiation plus temozolomide therapy followed by adjuvant temozolomide therapy in patients with newly diagnosed GBM.

PATIENTS AND METHODS

Sixty-four patients were enrolled onto this open-label, phase II trial. Temozolomide (75 mg/m(2)/d x 7 d/wk for 6 weeks) was administered orally concomitant with fractionated radiotherapy (60 Gy total dose: 2 Gy x 5 d/wk for 6 weeks) followed by temozolomide monotherapy (200 mg/m(2)/d x 5 days, every 28 days for six cycles). The primary end points were safety and tolerability, and the secondary end point was overall survival.

RESULTS

Concomitant radiation plus temozolomide therapy was safe and well tolerated. Nonhematologic toxicities were rare and mild to moderate in severity. During the concomitant treatment phase, grade 3 or 4 neutropenia, thrombocytopenia, or both were observed in 6% of patients, including two severe infections with Pneumocystis carinii. During adjuvant temozolomide, 2% and 6% of cycles were associated with grade 3 and 4 neutropenia or thrombocytopenia, respectively. Median survival was 16 months, and the 1- and 2-year survival rates were 58% and 31%, respectively. Patients younger than 50 years old and patients who underwent debulking surgery had the best survival outcome.

CONCLUSION

Continuous daily temozolomide and concomitant radiation is safe. This regimen of concomitant chemoradiotherapy followed by adjuvant chemotherapy may prolong the survival of patients with glioblastoma. Further investigation is warranted, and a randomized trial is ongoing.

Dynamic contrast-enhanced magnetic resonance imaging as a surrogate marker of tumor response to anti-angiogenic therapy in a xenograft model of glioblastoma multiforme

PURPOSE

To evaluate the effects of a neutralizing anti-vascular endothelial growth factor (anti-VEGF) antibody on tumor microvascular permeability, a proposed indicator of angiogenesis, and tumor growth in a rodent malignant glioma model.

MATERIALS AND METHODS

A dynamic contrast-enhanced magnetic resonance imaging (MRI) technique, permitting noninvasive in vivo and in situ assessment of potential therapeutic effects, was used to measure tumor microvascular characteristics and volumes. U-87, a cell line derived from a human glioblastoma multiforme, was implanted orthotopically into brains of athymic homozygous nude rats.

RESULTS

Treatment with the monoclonal antibody A4.6.1, specific for VEGF, significantly inhibited tumor microvascular permeability (6.1 +/- 3.6 mL min(-1)100 cc(-1)), compared to the control, saline-treated tumors (28.6 +/- 8.6 mL min(-1)100 cc(-1)), and significantly suppressed tumor growth (P <.05).

CONCLUSION

Findings demonstrate that tumor vascular permeability and tumor growth can be inhibited by neutralization of endogenous VEGF and suggest that angiogenesis with the maintenance of endothelial hyperpermeability requires the presence of VEGF within the tissue microenvironment. Changes in tumor vessel permeability and tumor volumes as measured by contrast-enhanced MRI provide an assay that could prove useful for clinical monitoring of anti-angiogenic therapies in brain tumors.

Transplant tumor registry: donors with central nervous system tumors1

BACKGROUND

Despite 13,000 central nervous system (CNS) tumor deaths per year in the United States, CNS tumor donors comprise only 1% of cadaveric donors recovered per year. Concern about tumor transmission may be a possible reason for this very small percentage. Both the size of the candidate waiting list and the number of deaths on the waiting list are progressively increasing because of the donor shortage.

METHODS

During a 96-month period, the United Network for Organ Sharing recorded 42,340 cadaver donors of whom 397 had a past history of a CNS tumor or the cause of death listed as a CNS tumor. A total of 1,220 organs were transplanted from these 397 donors. All recipients who reported a posttransplant malignancy during a mean follow-up of 36 months were identified.

RESULTS

There was no difference in patient survival of organs from CNS tumor donors when compared to donors with no CNS tumors. CNS tumor donors were not used more often for either urgent or older recipients. A total of 39 patients reported posttransplant malignancies but none of these tumors were donor-derived. There is a wide variation in the number of CNS tumor donors utilized by individual organ procurement organizations.

CONCLUSIONS

The risk of tumor transmission from donors with CNS malignancies seems to be small. Certain tumors, such as glioblastoma multiforme and medulloblastoma, carry a high risk of transmission and should be avoided. The risk of tumor transmission should be weighed against the risk of the patient dying on the waiting list without a transplant.

Salvage chemotherapy with CPT-11 for recurrent glioblastoma multiforme

BACKGROUND

A prospective Phase II study of CPT-11 in adult patients with recurrent supratentorial glioblastoma multiforme (GBM).

METHODS

Forty patients (25 men, 15 women) ages 32-71 years (median 59), with recurrent GBM were treated. All patients had previously been treated with surgery and involved field radiotherapy (median dose 60 Gy; range 59-60). Additionally, all patients were treated with adjuvant chemotherapy (BCNU in 20, PCV in 18, Procarbazine in 2). Twenty-five patients (62%) were on anticonvulsants (phenytoin in 15, carbamazepine in 10) and 26 patients (65%) were on dexamethasone. Recurrent disease was defined by neuroradiographic disease progression (>25% increase in tumor dimensions) using gadolinium-enhanced MR imaging. The starting dose of CPT-11 was 400 mg/m2 followed in three weeks by 500 mg/m2, operationally defined as one cycle. At week 6, all patients were evaluated with MRI and neurological examination.

RESULTS

All patients were evaluable. Two doses (one cycle) of CPT-11 were administered to all patients. CPT-11-related toxicity included: diarrhea (16 patients, 40%); thrombocytopenia (9 patients, 23%); and neutropenia (6 patients, 15%). No patient required transfusion nor was treatment for neutropenic fever required. No treatment-related deaths were observed. All patients demonstrated progressive disease following one cycle of CPT-11.

CONCLUSIONS

The lack of response to CPT-11 in this patient group with recurrent GBM suggests either CPT-11 has minimal activity or CPT-11 doses/schedule utilized in this study were sub-optimal. The latter is supported by the modest toxicity seen in this study and the previously documented enhanced clearance of CPT-11 in patients on anticonvulsants and dexamethasone.

Effect of therapeutic ionizing radiation on the human brain

We test a hypothesis that fractionated radiation therapy within a therapeutic dose range is associated with a dose-related change in normal brain, detectable by quantitative magnetic resonance imaging. A total of 33 patients were examined by quantitative magnetic resonance imaging to measure brain tissue spin-lattice relaxation time (T1) before treatment, and at various times during and after radiation therapy. A T1 map was generated at each time point, and radiation therapy isodose contours were superimposed on the corresponding segmented T1 map. Changes in white matter and gray matter T1 were analyzed as a function of radiation therapy dose and time since treatment, controlling for patient age and tumor site. In white matter, a dose level of more than 20 Gy was associated with a dose-dependent decrease in T1 over time, which became significant 6 months after treatment. There was no significant change in T1 of gray matter over time, at radiation therapy doses of less than 60 Gy. However, GM in close proximity to the tumor had a lower T1 before therapy. Our results represent the first radiation dose-response data derived from pediatric brain in vivo. These findings confirm that white matter is more vulnerable to radiation-induced change than is gray matter, and suggest that T1 mapping is sensitive to radiation-related changes over a broad dose range (20 to 60 Gy). Human white matter T1 is not sensitive to radiation therapy of less than 20 Gy, and gray matter T1 is unchanged over the dose range used to treat human brain tumor. The reduction of gray matter T1 near the tumor could result from compression of cortical parenchyma near the growing tumor mass, or from tumor cell invasion directly into the parenchyma. If brain T1 is a surrogate for radiation effect, reducing the volume of normal white matter receiving more than 20 Gy could be an important treatment planning goal.

AT1 receptor is present in glioma cells; its blockage reduces the growth of rat glioma

Malignancy of neoplasms is partly dependent on angiogenesis. Angiotensin II mediates angiogenesis and transcription of growth-related factors through stimulation of the AT1 receptor (AT1R). Losartan, a drug used mostly for treatment of hypertension, binds strongly to this receptor. We found the presence of AT1 receptor on C6 glioma cells and studied the effect of Losartan on the growth and angiogenesis of C6 rat glioma; Losartan in dose of 80 mg/kg induced 79% reduction of tumoural volume with a significant decrease of vascular density, mitotic index and cell proliferation. Our results demonstrate the conspicuous presence of AT1R in malignant glial cells and a favourable therapeutic response in experimental glioma by selective blockage of the AT1 receptor.

[Gross tumor volume (GTV) and clinical target volume (CTV) in adult gliomas]

Glioblastoma multiform and astrocytoma are the most frequent primary cancer of the central nervous system of adult. Definitions of gross tumor volume (GTV) and clinical target volume (CTV) are based on the confrontation of clinical presentation (age, performance status, neurologic symptoms...), histological type and imaging aspects. For glioblastoma multiform, the GTV can be defined by the area of contrast enhancement observed on the CT scan or MRI. Definition of the CTV can be more difficult and have to take into account the risk of presence of isolated malignant cells in the oedema surrounding the tumor or in the adjacent brain structures. The classical concept of GTV plus a safety margin of 2 cm around is discussed with a CTV containing at least all the oedematous area and eventually adjacent brain structures (nuclei, corpus callosum or other long associative fibers...). For low grade astrocytoma, the definition of GTV can be difficult if the tumoral infiltration is diffuse without nodular visible tumor. CTV corresponds to at least T2 MRI hypersignal area when visible. For postoperative tumor, technical considerations are important for the detection of residual tumor. A safety margin around the resected area is designed according to the risk of presence of isolated cells or involvement of adjacent brain structures.

Oligodendrocyte lineage genes (OLIG) as molecular markers for human glial brain tumors

The most common primary tumors of the human brain are thought to be of glial cell origin. However, glial cell neoplasms cannot be fully classified by cellular morphology or with conventional markers for astrocytes, oligodendrocytes, or their progenitors. Recent insights into central nervous system tumorigenesis suggest that novel molecular markers might be found among factors that have roles in glial development. Oligodendrocyte lineage genes (Olig1/2) encode basic helix-loop-helix transcription factors. In the rodent central nervous system, they are expressed exclusively in oligodendrocytes and oligodendrocyte progenitors, and Olig1 can promote formation of an chondroitin sulfate proteoglycon-positive glial progenitor. Here we show that human OLIG genes are expressed strongly in oligodendroglioma, contrasting absent or low expression in astrocytoma. Our data provide evidence that neoplastic cells of oligodendroglioma resemble oligodendrocytes or their progenitor cells and may derive from cells of this lineage. They further suggest the diagnostic potential of OLIG markers to augment identification of oligodendroglial tumors.

Regulating proliferation during retinal development

Recent studies have shown that components of the cell-cycle machinery can have diverse and unexpected roles in the retina. Cyclin-kinase inhibitors, for example, have been implicated as regulators of cell-fate decisions during histogenesis and reactive gliosis in the adult tissue after injury. Also, various mechanisms have been identified that can compensate for extra rounds of cell division when the normal timing of the cell-cycle exit is perturbed. Surprisingly, distinct components of the cell-cycle machinery seem to be used during different stages of development, and different organisms might rely on distinct pathways. Such detailed studies on the regulation of proliferation in complex multicellular tissues during development have not only advanced our knowledge of the ways in which proliferation is controlled, but might also help us to understand the degenerative disorders that are associated with gliosis and some types of tumorigenesis.