The role of chemotherapy in the treatment of primary tumors of the central nervous system

iRGD-mediated core-shell nanoparticles loading carmustine and O6-benzylguanine for glioma therapy

iRGD (internalizing RGD) with high affinity to αν integrins was reported to enhance tumor penetrability by binding to neuropilin-1 (NRP-1). Based on our previous study, chitosan surface-modified poly (lactide-co-glycolides) nanoparticles (PLGA/CS NPs), loaded with carmustine (BCNU) and its sensitizer (O⁶-benzylguanine, BG) showed stronger anti-tumor effect than free drugs. In present study, PLGA/CS NPs (NPs) with core-shell structure were prepared and modified with iRGD or mPEG. F98, C6 or U87 cell lines with different receptors levels were selected for in vitro and in vivo studies. After administration of iRGD-mediated NPs, including iRGD-modified NPs (iRGD-NPs) and co-administration of iRGD and NPs (iRGD + NPs), their effects on glioma were compared with NPs. iRGD-NPs showed stronger cytotoxicity and cellular uptake than other groups. iRGD-NPs and iRGD + NPs displayed deeper tumor penetration and stronger anti-invasion effect on three dimensional (3D) glioma spheroids than NPs. On F98 glioma-bearing mice model, iRGD-mediated NPs showed enhanced crossing BBB ability and brain tumor accumulation levels. Correspondingly, the median survival time of iRGD + NPs, iRGD-NPs and NPs groups were 58, 49 and 34.5 days, respectively. Present studies supported the iRGD-mediated strategy to improve the efficacy of antitumor drug delivery system. Importantly, co-administration of iRGD may be a greater way over the conjugation of iRGD.

Distinct cellular responses induced by saporin and a transferrin-saporin conjugate in two different human glioblastoma cell lines

Glioblastoma multiforme (GBM) is the most common primary brain tumour in adults, with a median survival of ~12-18 months post-diagnosis. GBM usually recurs within 12 months post-resection, with poor prognosis. Thus, novel therapeutic strategies to target and kill GBM cells are urgently needed. The marked difference of tumour cells with respect to normal brain cells renders glioblastoma a good candidate for selective targeted therapies. Recent experimental strategies focus on over expressed cell surface receptors. Targeted toxins represent a new class of selective molecules composed by a potent protein toxin and a carrier ligand. Targeted toxins approaches against glioblastoma were under investigation in phase I and II clinical trials with several immunotoxins (IT)/ligand toxins such as IL4-Pseudomonas aeruginosa exotoxin A (IL4-PE, NBI-3001), tumour growth factor fused to PE38, a shorter PE variant, (TGF)alpha-TP-38, IL13-PE38, and a transferrin-C diphtheriae toxin mutant (Tf-CRM107). In this work, we studied the effects of the plant ribosome-inactivating saporin and of its chimera transferrin-saporin against two different GBM cell lines. The data obtained here indicate that cell proliferation is affected by the toxin treatments but that different mechanisms are used, directly linked to the presence of an active or inactive p53. A model is proposed for these alternative intracellular pathways.

Treatment of recurrent glioblastoma with intra-arterial BCNU [1, 3-bis (2-chloroethyl)-1-nitrosourea]

Contemporary therapies for patients with glioblastomas remain marginally efficient, and recurrence following surgery, radiation therapy and adjuvant chemotherapy is practically universal. The major obstacles to the successful use of chemotherapy for CNS tumors are the drug delivery to the tumor site and the infusion of chemotherapeutic agents directly into the arterial supply of a tumor. The latter could provide a pharmacokinetic advantage by enhancing drug delivery to the tumor. Sixteen patients with recurrent unilateral glioblastomas treated with intra-arterial BCNU were evaluated retrospectively. During the infusion, eleven patients referred pain in the ipsilateral eye, five patients were nauseated, three reported headache, one patient presented mental confusion, while two presented focal signs. There were two deaths during the course of therapy. Four patients achieved temporary clinical improvement, seven showed disease stability, and three presented clinical deterioration. The median total survival time was 87.9 weeks. Unilateral vision loss and focal signs were observed as delayed complications of this treatment. This study has confirmed previous reports indicating that arterial chemotherapy is clearly not curative, and presents serious toxicity. Only through a randomized prospective study performed in a large series of patients can the questions concerning survival period increment be answered properly

External beam irradiation and the combination of cisplatin and carmustine followed by carmustine alone for the treatment of high-grade glioma: a phase 2 Southwest Oncology Group trial

BACKGROUND

The poor prognosis reported for patients with high-grade glial neoplasms indicates a need for the development of multimodality therapeutic approaches. The addition of chemotherapy has contributed variably to increased survival. The objective of the current study (Southwest Oncology Group [SWOG] 9016) was to determine whether concurrent radiotherapy and chemotherapy with the combination of carmustine and cisplatin could be given safely in a cooperative group setting. Additional objectives included the estimation of response rate, the rate of disease stabilization, and the probability of 1-year survival.

METHODS

SWOG 9016 study included 59 eligible patients with grade III or IV astrocytoma who received radiotherapy concurrently with carmustine/cisplatin chemotherapy. Patients were required to have either measurable or evaluable disease. The therapeutic endpoints were comprised of complete response (CR), partial response (PR), or progressive disease (PD).

RESULTS

Six patients achieved a CR (CR rate of 10%; 95% confidence interval [95% CI], 4-21%), 4 achieved a PR (PR rate of 7%; 95% CI, 2-16%), and 2 patients (3%) experienced an unconfirmed response. Twenty-four patients (41%; 95% CI, 28-54%) had stable disease and 10 patients (17%) demonstrated PD. The overall disease stabilization rate (CR + PR + stable disease, excluding unconfirmed response) was 58% (95% CI, 44-70%).

CONCLUSIONS

Despite the presence of a cohort of long-term survivors, the results of the current study do not appear to support the additional study or routine use of concurrent cisplatin and carmustine.

Biomolecular characterization of human glioblastoma cells in primary cultures: differentiating and antiangiogenic effects of natural and synthetic PPARgamma agonists

Gliomas are the most commonly diagnosed malignant brain primary tumors. Prognosis of patients with high-grade gliomas is poor and scarcely affected by radiotherapy and chemotherapy. Several studies have reported antiproliferative and/or differentiating activities of some lipophylic molecules on glioblastoma cells. Some of these activities in cell signaling are mediated by a class of transcriptional factors referred to as peroxisome proliferator-activated receptors (PPARs). PPARgamma has been identified in transformed neural cells of human origin and it has been demonstrated that PPARgamma agonists decrease cell proliferation, stimulate apoptosis and induce morphological changes and expression of markers typical of a more differentiated phenotype in glioblastoma and astrocytoma cell lines. These findings arise from studies mainly performed on long-term cultured transformed cell lines. Such experimental models do not exactly reproduce the in vivo environment since long-term culture often results in the accumulation of further molecular alterations in the cells. To be as close as possible to the in vivo condition, in the present work we investigated the effects of PPARgamma natural and synthetic ligands on the biomolecular features of primary cultures of human glioblastoma cells derived from surgical specimens. We provide evidence that PPARgamma agonists may interfere with glioblastoma growth and malignancy and might be taken in account as novel antitumoral drugs.

PPARgamma-dependent effects of conjugated linoleic acid on the human glioblastoma cell line (ADF)

Conjugated linoleic acid (CLA) has been shown to exert beneficial effects against carcinogenesis, atherosclerosis and diabetes. It has been demonstrated that CLA modulates lipid metabolism through the activation of peroxisome proliferator-activated receptors (PPARs). The PPAR family comprises 3 closely related gene products, PPAR alpha, beta/delta and gamma, differing for tissue distribution, developmental expression and ligand specificity. It has also been demonstrated that activated PPARgamma results in growth inhibition and differentiation of transformed cells. These observations stimulated a great interest toward PPARgamma ligands as potential anticancer drugs to be used in a differentiation therapy. Glioblastomas are the most commonly diagnosed primary tumors of the brain in humans. The prognosis of patients with high-grade gliomas is poor and only marginally improved by chemotherapy. The aim of this work was to study the effects of CLA and of a specific synthetic PPARgamma ligand on cell growth, differentiation and death of a human glioblastoma cell line as well as on parameters responsible for the metastatic behavior of this tumor. We demonstrate here that CLA and PPARgamma agonist strongly inhibit cell growth and proliferation rate and induce apoptosis. Moreover, both treatments decrease cell migration and invasiveness. The results obtained show that CLA acts, directly or indirectly, as a PPARgamma activator, strongly suggesting that this naturally occurring fatty acid may be used as brain antitumor drug and as a chemopreventive agent. Moreover, the gamma-agonist, once experimented and validated on man, may represent a useful coadjuvant in glioblastoma therapy and in the prevention of recurrences.

Radiotherapy for intracranial and spinal ependymomas. A retrospective analysis

BACKGROUND

The low incidence of ependymomas results in limited treatment experience. While standard therapy consists of surgery and postoperative radiotherapy, irradiation techniques are still subject to discussion. We report the experience from Münster over the last 35 years.

PATIENTS AND METHODS

Since 1961, 25 evaluable patients with ependymoma were irradiated in Münster: 17 intracranial and 8 spinal tumors. Fourteen of 25 patients underwent subtotal resection. Fifteen of 25 patients were treated by local irradiation, 10 of 25 with large-field techniques (whole-brain/cranio-spinal irradiation) and an additional tumor boost. The median tumor dose amounted to 50 Gy (16 to 65 Gy). Sites of recurrence were analyzed and correlated with the irradiated region.

RESULTS

Twelve recurrences were observed. Six of 12 could be exactly related to the irradiation portals and were found well inside the local or boost fields. The remaining 6 tumors also recurred locally; whether they were in-field or field margin recurrences was not to be discerned by the imaging available at the time. No out-field recurrences or spinal seeding were observed. For 8 of 17 locally irradiated patients with intracranial ependymomas, 5 local recurrences were recorded. In 9 of 17 patients receiving whole-brain or cranio-spinal irradiation, 6 local recurrences were found. Two of 8 spinal tumors recurred locally.

CONCLUSIONS

All tumors recurred within the former tumor bed. In the remaining cranio-spinal axis no recurrences or metastases were found. Similar results are reported from current literature. The value of large-field techniques (whole brain/spinal irradiation) is to be questioned. Modern methods like IORT or stereotactic radiotherapy might be able to deliver a higher tumor dose without increasing toxicity.

Synchronous radiochemotherapy in unfavorable brain tumors of children and young adults

The prognosis of patients with incompletely resected malignant brain tumors is almost fatal. In an attempt to improve the outcome of children and young adults with unfavorable brain tumors an intensive multimodal therapeutic strategy was developed combining simultaneous (hyper)fractionated external beam irradiation and conventional adjuvant chemotherapy after initial surgery. 17 patients aged between 2.10 and 25.11 years were entered into the study. 16/17 patients were treated according to the German/Austrian Pediatric Brain Tumor Study Group multicenter trial HIT '91. They are not protocol patients of this HIT '91 trial. Induction chemotherapy consisted of 2 courses of ifosfamide (3 g/m2/d) on days 1-3, etoposide (150 mg/m2/d) on days 4-6, methotrexate (5 g/m2) on days 15 and 22, cisplatin (40 mg/m2/d) and cytarabine (400 mg/m2/d) on days 29-31. Three weeks after the last dose of cisplatin/cytarabine the second course of chemotherapy was started. The last patient entered into the study received a modified therapy containing ifosfamide, cisplatin and etoposide. Synchronously at a median of 12 days after initiation of chemotherapy 12/17 patients received local radiotherapy (6000-7040 cGy) to the brain and 5/17 patients craniospinal irradiation (3520 cGy with a tumor boost of 1400-2000 cGy). 4-6 weeks after completion of the second course of chemotherapy maintenance therapy was started with carmustine (CCNU) (75 mg/m2) and carboplatin (400 mg/m2) each on day 1 and vincristine (1.5 mg/m2) on day 1, 8, 15. This course was repeated eight times every six weeks. 9/17 patients are alive at a median follow-up of 25 months (range 5-50) with 4 complete remissions, 2 partial remissions and 1 stable disease lasting 42+ months. Two patients, who initially had stable disease, progressed, but are still alive at 31+ and 41+ months after diagnosis. Median progression-free survival and median overall survival is 19 and 36 months, respectively. Hematologic and methotrexate-induced toxicity were severe and resulted in one therapy-related death. However, radiotherapy concomitant to chemotherapy appears to be an effective method of treatment for brain tumors with poor prognosis, though toxicity is severe in some cases.

Antiproliferative activity of liposomal epirubicin on experimental human gliomas in vitro and in vivo after intratumoral/interstitial application

Liposomal epirubicin was prepared using the controlled detergent dialysis method. The entrapment rate was 65.5 +/- 6.4%. The mean particle size was 210 +/- 38 nm. In vitro, a concentration-dependent antiproliferative activity of free epirubicin was observed. Liposome-entrapped epirubicin was superior to the free drug; the ID50 of the liposomal preparation was about 1.6-fold lower as compared to the free drug. Intratumoral/interstitial (i.t./i.s.) application of liposomal epirubicin was likewise superior to i.t./i.s. application of the free drug.

High dose chemotherapy for the treatment of malignant brain tumors

Conventional treatment of malignant high grade gliomas includes maximal resection followed by external beam radiotherapy. The addition of adjuvant chemotherapy has provided little improvement in the median duration of survival for these patients, particularly those patients with glioblastoma multiforme. The failure of conventional dose chemotherapy to improve the outcome of patients with high grade brain tumors has led several investigators to utilize high dose chemotherapy in order to overcome the limited benefit seen with conventional dose therapy which is due to intrinsic drug resistance as well as the impermeability of blood brain barrier. The majority of published studies utilizing this approach suggest that the addition of high dose chemotherapy with bone marrow transplant is of marginal benefit. However, most of these trials include small numbers of patients with advanced, refractory disease. A few trials have been reported utilizing high dose therapy in an adjuvant setting and the data from these studies are somewhat more promising. This review will analyze these studies and also discuss possible modifications of this approach in order to improve this aggressive treatment for patients who otherwise would have a dismal prognosis.