A North Central Cancer Treatment Group phase II trial of topotecan in relapsed gliomas

Cell primitive-based biomimetic nanomaterials for Alzheimer's disease targeting and therapy

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, which is not just confined to the older population. Although developments have been made in AD treatment, various limitations remain to be addressed. These are partly contributed by biological hurdles, such as the blood-brain barrier and peripheral side effects, as well as by lack of carriers that can efficiently deliver the therapeutics to the brain while preserving their therapeutic efficacy. The increasing AD prevalence and the unavailability of effective treatments have encouraged researchers to develop improved, convenient, and affordable therapies. Functional materials based on primitive cells and nanotechnology are emerging as attractive therapeutics in AD treatment. Cell primitives possess distinct biological functions, including long-term circulation, lesion site targeting, and immune suppression. This review summarizes the challenges in the delivery of AD drugs and recent advances in cell primitive-based materials for AD treatment. Various cell primitives, such as cells, extracellular vesicles, and cell membranes, are presented together with their distinctive biological functions and construction strategies. Moreover, future research directions are discussed on the basis of foreseeable challenges and perspectives.

Topotecan is a potent inhibitor of SUMOylation in glioblastoma multiforme and alters both cellular replication and metabolic programming

Protein SUMOylation is a dynamic post-translational modification shown to be involved in a diverse set of physiologic processes throughout the cell. SUMOylation has also been shown to play a role in the pathobiology of myriad cancers, one of which is glioblastoma multiforme (GBM). As such, the clinical significance and therapeutic utility offered via the selective control of global SUMOylation is readily apparent. There are, however, relatively few known/effective inhibitors of global SUMO-conjugation. Herein we describe the identification of topotecan as a novel inhibitor of global SUMOylation. We also provide evidence that inhibition of SUMOylation by topotecan is associated with reduced levels of CDK6 and HIF-1α, as well as pronounced changes in cell cycle progression and cellular metabolism, thereby highlighting its putative role as an adjuvant therapy in defined GBM patient populations.

Convection-Enhanced Delivery

Convection-enhanced delivery (CED) is a promising technique that generates a pressure gradient at the tip of an infusion catheter to deliver therapeutics directly through the interstitial spaces of the central nervous system. It addresses and offers solutions to many limitations of conventional techniques, allowing for delivery past the blood-brain barrier in a targeted and safe manner that can achieve therapeutic drug concentrations. CED is a broadly applicable technique that can be used to deliver a variety of therapeutic compounds for a diversity of diseases, including malignant gliomas, Parkinson's disease, and Alzheimer's disease. While a number of technological advances have been made since its development in the early 1990s, clinical trials with CED have been largely unsuccessful, and have illuminated a number of parameters that still need to be addressed for successful clinical application. This review addresses the physical principles behind CED, limitations in the technique, as well as means to overcome these limitations, clinical trials that have been performed, and future developments.

Convection-enhanced delivery for glioblastoma: targeted delivery of antitumor therapeutics

Glioblastoma is the most common primary brain tumor in adults and carries a dismal prognosis despite advancements in treatment. Diffuse tumor infiltration precludes curative surgical resection and necessitates advancements in drug delivery mechanisms. Convection-enhanced delivery (CED) enables continuous local drug delivery for a diverse population of antitumor agents. Importantly, CED circumvents therapeutic challenges posed by the blood-brain barrier by facilitating concentrated local therapeutic drug delivery with limited systemic effects. Here, we present a concise review of properties essential for safe and efficient convection-enhanced drug delivery, as well as a focused review of clinical studies evaluating CED in the treatment of glioblastoma.

Experience with irinotecan for the treatment of malignant glioma

Malignant glioma is the most commonly occurring primary malignant brain tumor. It is difficult to treat and is usually associated with an inexorable, rapidly fatal clinical course. Chemotherapy, radiotherapy, and surgical excision are core components in the management of malignant glioma. However, chemotherapy, even with the most active regimens currently available, achieves only modest improvement in overall survival. Novel agents and new approaches to therapy are required to improve clinical outcomes. Irinotecan, a first-line treatment for metastatic colorectal cancer and an agent with high activity against solid tumors of the gastrointestinal tract, is an inhibitor of topoisomerase I, a critical enzyme needed for DNA transcription. Irinotecan crosses the blood-brain barrier and, in preclinical investigations, has demonstrated cytotoxic activity against central nervous system tumor xenografts. Its antitumor activity has also been demonstrated against glioblastoma cells with multidrug resistance. Studies in adult and pediatric patients with recurrent, intractable malignant glioma have evaluated irinotecan as monotherapy and in combination with other agents, including temozolomide, carmustine, thalidomide, and bevacizumab. Studies of irinotecan in combination with other medications, particularly temozolomide and bevacizumab, have yielded promising results. Irinotecan monotherapy has demonstrated efficacy; however, its efficacy appears to be enhanced when used in combination with other chemotherapeutic agents. When administered concurrently with enzyme-inducing antiepileptic drugs, the dosage must be increased to compensate for enhanced cytochrome CY3A4/5 enzyme activity. Toxicities associated with irinotecan have been manageable; the most important dose-limiting toxicities are neutropenia and diarrhea. Irinotecan-based chemotherapy of malignant glioma merits further study.

Topotecan in combination with radiotherapy in unresectable glioblastoma: a phase 2 study

Improving glioblastoma multiforme (GBM) treatment with radio-chemotherapy remains a challenge. Topotecan is an attractive option as it exhibits growth inhibition of human glioma as well as brain penetration. The present study assessed the combination of radiotherapy (60 Gy/30 fractions/40 days) and topotecan (0.9 mg/m(2)/day on days 1-5 on weeks 1, 3 and 5) in 50 adults with histologically proven and untreated GBM. The incidence of non-hematological toxicities was low and grade 3-4 hematological toxicities were reported in 20 patients (mainly lymphopenia and neutropenia). Partial response and stabilization rates were 2% and 32%, respectively, with an overall time to progression of 12 weeks. One-year overall survival (OS) rate was 42%, with a median OS of 40 weeks. Topotecan in combination with radiotherapy was well tolerated. However, while response and stabilization concerned one-third of the patients, the study did not show increased benefits in terms of survival in patients with unresectable GBM.

Phase I and pharmacokinetic study of karenitecin in patients with recurrent malignant gliomas

Karenitecin is a highly lipophilic camptothecin analogue with a lactone ring that is relatively resistant to inactivating hydrolysis under physiologic conditions. This phase I clinical trial was conducted to determine the maximum tolerated dose (MTD) of karenitecin in adults with recurrent malignant glioma (MG), to describe the effects of enzyme-inducing antiseizure drugs (EIASDs) on its pharmacokinetics, and to obtain preliminary evidence of activity. Karenitecin was administered intravenously over 60 min daily for 5 consecutive days every 3 weeks to adults with recurrent MG who had no more than one prior chemotherapy regimen. The continual reassessment method was used to escalate doses, beginning at 1.0 mg/m(2)/day, in patients stratified by EIASD use. Treatment was continued until disease progression or treatment-related dose-limiting toxicity (DLT). Plasma pharmacokinetics was determined for the first daily dose of karenitecin. Thirty-two patients (median age, 52 years; median KPS score, 90) were accrued. Seventy-eight percent had glioblastoma, and 22% had anaplastic glioma. DLT was reversible neutropenia or thrombocytopenia. The MTD was 2.0 mg/m(2) in daggerEIASD patients and 1.5 mg/m(2) in -EIASD patients. The mean (+/-SD) total body clearance of karenitecin was 15.9 +/- 9.6 liters/h/m(2) in daggerEIASD patients and 10.2 +/- 3.5 liters/h/m(2) in -EIASD patients (p = 0.02). No objective responses were observed in 11 patients treated at or above the MTD. The total body clearance of karenitecin is significantly enhanced by the concurrent administration of EIASDs. This schedule of karenitecin, a novel lipophilic camptothecin analogue, has little activity in recurrent MG.

Improvement, clinical course, and quality of life after palliative radiotherapy for recurrent glioblastoma

The purpose of this review is to assess the palliative effect of re-irradiation in adult patients with recurrent supratentorial glioblastoma (GBM) previously treated with adjuvant or primary radiation therapy, with or without chemotherapy. From a comprehensive literature search, studies were identified reporting on survival, progression, and quality of life endpoints including, but not limited to, EORTC QLQ-C30 questionnaire, clinical symptoms, and ability to reduce dexamethasone. Data from more than 300 GBM patients (grade 3 anaplastic gliomas were excluded) demonstrate that re-irradiation yields 6-month PFS of 28% to 39% and 1-year overall survival of 18% to 48%, without additional chemotherapy (median value 26%). Patients with Karnofsky performance status <70 appeared to be at higher risk of early progression and apparently had lesser benefit from re-irradiation. Clinical improvement was observed in 24% to 45% of the patients. Most studies suggest that stabilization of the performance status is a realistic aim. In the studies reporting on corticosteroid usage during and after re-irradiation, 20% to 60% of the patients achieved a reduction in steroid dependency. Serious late toxicity was uncommon, especially after conventional treatment and fractionated stereotactic radiotherapy (FSRT). In light of recent technological advances such as FSRT and intensity modulated radiotherapy, which permit maximal sparing of normal brain, re-treatment seems attractive, and deserves scientific validation. Even fraction sizes of 3 to 5 Gy seem to be well tolerated in limited-volume recurrences as long as the total dose is limited to 30 to 35 Gy. Salvage chemotherapy or targeted agents should be prospectively tested against re-irradiation alone.

The relationship between six-month progression-free survival and 12-month overall survival end points for phase II trials in patients with glioblastoma multiforme

Common end points for phase II trials in patients with glioblastoma multiforme (GBM) are six-month progression-free survival (PFS6) and 12-month overall survival (OS12). OS12 can be accurately measured but may be confounded with subsequent therapies upon progression, whereas the converse is true for PFS6. Our goal was to assess the relationship between these end points separately for phase II trials in patients with newly diagnosed GBM and patients with recurrent GBM. Data were pooled from 11 North Central Cancer Treatment Group trials for patients with newly diagnosed GBM (n = 1348). All patients received radiotherapy and pharmaceutical therapy (before, during, or after radiotherapy). Data were pooled from 16 trials that used various pharmaceuticals in treating patients for recurrent GBM (n = 345). All trial regimens were declared nonefficacious by predefined criteria. Overall per-patient concordance was estimated with a kappa statistic. The relationship between OS12 and PFS6 across study arms was assessed by weighted linear regression and Pearson's correlation. Simulation was used to determine the agreement of study outcomes when using PFS6 versus OS12 end points. Cox models with progression status as a time-dependent variable and Kaplan-Meier estimators were used to ascertain the association between progression-free survival status and overall survival. At present, 97% of the patients with newly diagnosed GBM and 95% of those with recurrent GBM have died. The PFS6 and OS12 were 43% and 41%, respectively, for patients with newly diagnosed disease and 9% and 14% for patients with recurrent disease. There was only moderate concordance between the end points on both the patient level and the study level. For the simulation studies, we established phase II efficacy criteria for each end point by using the pooled estimates of OS12 (PFS6) as historical controls. The study decisions made using PFS6 and OS12 were in agreement 88% and 90% of the time for the trials of newly diagnosed and recurrent disease, respectively. Finally, there was a strong association between progression-free survival status and overall survival. PFS6 seems to be a reasonable end point for phase II trials in patients with recurrent glioblastoma.

Therapeutic options for recurrent high-grade glioma in adult patients: Recent advances

Despite of postoperative radiotherapy plus temozolomide for newly diagnosed glioblastoma multiforme (GBM) and improvements in the molecular characterization of high-grade glioma, these tumors continue to relapse. We reviewed all clinical studies of re-treatment published between May 2000 and September 2005. In groups of highly selected patients with re-treatment for GBM, median survival reaches 26-27 months. Re-treatment was stereotactic radiotherapy (mostly with additional chemotherapy) or re-resection plus either photodynamic treatment, radioimmunotherapy and temozolomide, or systemic and local chemotherapy. Thus, intense local treatment was always a component of more successful strategies. Additional data suggest that chemotherapy is more efficacious when minimal residual disease is present, although the recent trials have not uncovered a clear regimen of choice. Early trials of immunotherapy and toxin-delivery demonstrate the feasibility of these approaches and encouraging median survival times. Response to erlotinib was more common if tumors had epidermal growth factor receptor gene amplification, protein overexpression and low levels of phosphorylated PKB/Akt. Individual tailoring of such strategies based on molecular profiling is hoped to improve the outcome.

Pre-irradiation 9-Amino [20s] camptothecin (9-AC) in patients with newly diagnosed glioblastoma multiforme

PURPOSE

To evaluate the efficacy of 9-amino [20s] camptothecin (9-AC) given before radiation therapy to patients with newly diagnosed glioblastoma multiforme (GBM).

METHODS

Eligible patients had newly diagnosed GBM who had residual measurable contrast-enhancing tumor. The trial was a phase 2 trial of 9-AC at 1100 microg/m2 /24 h infused over 72 h every two weeks for up to six cycles in patients with newly diagnosed GBM before radiation therapy.

RESULTS

Fourteen patients entered the study and all were evaluable. All of the patients had progressive disease by imaging criteria after at least two cycles of 9-AC (1 month). The median overall survival was 7.5 months (range 1.5-18 months). The most common adverse event was transient lymphopenia (grade 3-4). One patient developed grade 4 neutropenic fever that resolved after three days of diagnosis.

CONCLUSIONS

9-AC lacks activity against glioblastoma multiforme (GBM). Further studies looking at the efficacy of 9-AC in GBM may be futile.

Open-label simultaneous radio-chemotherapy of glioblastoma multiforme with topotecan in adults

BACKGROUND

Due to its radioresistance, the prognosis of glioblastoma multiforme (GBM) remains poor. Therefore, we investigated the impact of simultaneous radio-chemotherapy with topotecan (Hycamtin) on clinical outcome, tolerability and quality of life.

PATIENTS AND METHODS

In this multicenter trial, 60 patients (19 females, 41 males) with histologically proven (5x biopsy, 31x subtotal resection, 24x total resection) GBM were included. Radio-Chemotherapy was performed with daily doses of 2.0 Gy (total, 60 Gy), and 0.5 mg (absolute dose) of topotecan intravenously 1 h prior to irradiation. Toxicity was assessed using common toxicity criteria (CTC). General condition and quality of life were assessed at baseline, at the end of therapy, and 6 weeks post-therapy. Local control and length of survival were compared with an historical control group of 67 patients only treated with postoperative radiotherapy following stereotactic biopsy (15x), subtotal resection (39x), or total resection (13x).

RESULTS

57 patients completed the therapy. Median radiation dose was 60 Gy (range 16-76 Gy). Median cumulative topotecan dose was 15 mg (range 7.5-18.5 mg). CTC toxicity grade 3 was observed in six patients and grade 4 toxicity in two patients (three events). Two patients died of septic disease. Mean Karnofsky index was 87% at baseline, 81% at the end of therapy, and 80% at 6 weeks post-therapy. Median survival time was 15 months, significantly longer than the 11 months seen in the control group (P < 0.002). Extent of tumour resection or patient age did not have a significant effect on survival.

CONCLUSION

This multimodal approach is well tolerated, and quality of life remains preserved. The relatively long median survival time is promising but a further randomised double blind placebo controlled parallel designed clinical trial should be performed to confirm these results.

Oral topotecan in children with recurrent or progressive high-grade glioma: a Phase I/II study by the German Society for Pediatric Oncology and Hematology

BACKGROUND

Continuous oral treatment with topotecan may be more effective than the typical 1-day and 5-day treatment schedules. In previous studies of continuous treatment with topotecan, increased intestinal side effects were reported in adult patients; however, the experience in pediatric patients and patients with high-grade glioma is quite limited.

METHODS

Thirty-two pediatric patients with recurrent high-grade glioma (16 females and 16 males; median age, 9.5 years) were enrolled in the current Phase I/II study. Tumor locations included the cerebral cortex (n = 5), pons (n = 18), and other sites (n = 9). An injectable formulation of topotecan was administered orally, in ice-cold orange juice, once daily. The starting dose of 0.4 mg/m(2) per day was escalated on a patient-by-patient basis. At each patient's maximum dose, blood samples were obtained for the determination of plasma hydroxytopotecan and topotecan lactone concentrations and for the calculation of pharmacokinetic quantities.

RESULTS

The toxicity criteria for a maximum tolerated topotecan dose were met in only 19 patients. The primary toxicity type was hematologic. The median maximum tolerated dose was 0.9 mg/m(2) per day (n = 19). The calculated maximum total plasma topotecan concentration was 3.8 ng/mL (n = 7), with an area under the concentration-time curve of 38.4 ng. hours/mL and a half-life of 4.1 hours, which would result in the complete disappearance of topotecan from the plasma after 12 hours. Objective responses were observed in 2 of 13 evaluable patients and lasted for 2.5 and 9 months, respectively (continuous clinical remission, 1 of 14 patients; partial response, 2 of 14 patients; stable disease, 7 of 14 patients; progressive disease, 4 of 14 patients).

CONCLUSIONS

Oral topotecan (median dose, 0.9 mg/m(2) per day) administered once daily was well tolerated and somewhat effective in children with recurrent high-grade glioma. A schedule in which the daily dose is split so that dosing is performed twice daily may be superior to the current schedule.

Phase I study of topotecan in combination with concurrent radiotherapy in adults with glioblastoma

A phase I study was performed to determine the maximum tolerated dose and the recommended dose of continuous intravenous infusion of topotecan in combination with radiotherapy (RT) in patients with previously untreated glioblastoma multiforme (GBM). Twenty patients with histologically proven GBM and 1 with rhabdoid tumor were enrolled. After surgery or stereotactic biopsy, patients received cranial RT (60 Gy/30 fractions/40 days) and 3 cycles of topotecan as continuous infusion (CIV) from day 1 to 5 on weeks 1, 3, and 5 during RT. The dose of topotecan was escalated from 0.6 to 1.0 mg/m2/day. Four dose levels were tested. One grade 4 thrombocytopenia was seen at level 1 (topotecan dose 0.6 mg/m2/day; 6 patients). No dose-limiting toxicity was seen at level 2 (0.8 mg/m2/day; 3 patients) or an intermediate level of 2 bis (0.9 mg/m2/day; 6 patients). Six patients were included at level 3 (1.0 mg/m2/day), 4 of whom experienced dose-limiting toxicities, including 3 episodes of grade 4 thrombocytopenia, 1 platelet transfusion, 1 febrile neutropenia, and 1 grade 4 neutropenia of more than 7 days. Eighty percent of patients with GBM were alive at 12 months. The dose-limiting toxicity of topotecan administered as CIV for 5 days every 2 weeks is hematological. The maximum tolerated dose is 1.0 mg/m2/day and the recommended dose is 0.9 mg/m2/day. A phase II trial using the recommended dose of topotecan is ongoing.

Pharmacotherapy of malignant astrocytomas of children and adults: current strategies and future trends

This article reviews the conceptual progression in the pharmacological therapy of malignant astrocytoma (MA) over the past decade, and its future trends. It is a selective rather than an exhaustive inventory of literature citations. The experience of the Brain Tumour Cooperative Group (BTCG) and earlier phase III trials are summarised to place subsequent phase II and I studies of single and combination agent chemotherapy in perspective. The BTCG experience of the 1970s to 1980s may be summarised to indicate that external beam radiotherapy (EBRT) is therapeutic, although not curative, and not further improved upon by altering fractionation schedules, or the addition of radioenhancers. Whole brain and reduced whole brain EBRT with focal boost were comparable regimens. Nitrosourea-based, adjuvant chemotherapy provided a modest improvement in survival among adult patients, which was comparable with that of other single drugs or multidrug regimes. The multiagent schedules, however, had a correspondingly higher toxicity rate. Intra-arterial administration was associated with significant risk, which conferred no therapeutic advantage. The trend of the past decade has been towards multiagent chemotherapy although its benefit cannot be predicted from the classic prognostic factors. Published experience with investigational trials utilising myeloablative chemotherapy with autologous bone marrow or peripheral blood stem cell haemopoietic support, drug delivery enhancement methods and radiosensitisers is critically reviewed. None of these approaches have achieved wide-spread acceptance in the treatment of adult patients with MA. Greater attention is placed on recent 'chemoradiotherapy' trials, which attempt to integrate and maximise the cytoreductive potential of both modalities. This approach holds promise as an effective means to delay or overcome the evolution of tumour resistance, which is probably one of the dominant determinants of prognosis. However, the efficacy of this approach remains unproven. New chemotherapeutic agents as well as biological response modifiers, protein kinase inhibitors, angiogenesis inhibitors and gene therapy are also discussed; their role in the therapeutic armamentarium has not been defined.

Changing boundaries in the treatment of malignant gliomas

Malignant gliomas are still among the most lethal and difficult tumors to treat; even the most intensive combinations of radio- and chemotherapy are not curative and yield only a modest impact on survival for most of these patients, as long-term survivors are less than 10%. There is a major need for new chemotherapeutic drugs and alternative therapeutic modalities. This review aims to define the best standard treatment in the common clinical practice and also summarizes the most promising lines of investigational research in the field of neuro-oncology, which will probably offer new and long-awaited valid therapy options for brain tumor patients.