Treatment of neoplastic meningeal xenografts by intraventricular administration of an antiganglioside monoclonal antibody, 3F8

Antibody-based immunotherapy in high-risk neuroblastoma

Although great advances have been made in the treatment of low- and intermediate-risk neuroblastoma in recent years, the prognosis for advanced disease remains poor. Therapies based on monoclonal antibodies that specifically target tumour cells have shown promise for treatment of high-risk neuroblastoma. This article reviews the use of monoclonal antibodies either as monotherapy or as part of a multifaceted treatment approach for advanced neuroblastoma, and explains how toxins, cytokines, radioactive isotopes or chemotherapeutic drugs can be conjugated to antibodies to enhance their effects. Tumour resistance, the development of blocking antibodies, and other problems hindering the effectiveness of monoclonal antibodies are also discussed. Future therapies under investigation in the area of immunotherapy for neuroblastoma are considered.

Phase I study of targeted radioimmunotherapy for leptomeningeal cancers using intra-Ommaya 131-I-3F8

PURPOSE

Tumors metastasizing to the CNS and leptomeninges (LM) are associated with significant mortality. We tested the toxicity, pharmacokinetics, and dosimetry of intraventricular iodine-131-labeled monoclonal antibody 3F8 (131I-3F8) targeting GD2-positive CNS/LM disease in a phase I clinical trial.

PATIENTS AND METHODS

Adequate CSF flow was determined by pretreatment indium-111-DTPA studies. Fifteen patients received a tracer (1 to 2 mCi) and therapeutic injection (10 to 20 mCi) of intra-Ommaya 131I-3F8. 131I-3F8 pharmacokinetics were studied by serial CSF and blood samplings. Dosimetry was based on pharmacokinetics and region of interest (ROI) analyses on whole-body gamma camera scans. Tumor response was determined by clinical, radiographic, and cytologic criteria.

RESULTS

Total absorbed CSF dose was 1.12 to 13.00 Gy by sampling and 1.00 to 13.70 Gy by ROI data. Average dosimetry ratio (Gy/mCi) of the therapy/tracer administration was 0.88 (+/- 0.58) and 1.08 (+/- 0.66) based on CSF pharmacokinetics and ROI analysis, respectively. CSF half-life by sampling was 3 to 12.9 hours. Toxicities included self-limited headache, fever, and vomiting. Dose-limiting toxicity was reached at the 20-mCi dose, when transient elevations in intracranial pressure and chemical meningitis were seen. Three of 13 assessable patients achieved objective radiographic and/or cytologic responses. No late toxicities have been seen in two patients who remain in remission off therapy for more than 3.5 years.

CONCLUSION

Intra-Ommaya 131I-3F8 was generally well tolerated; the maximum-tolerated dose was 10 mCi. A high CSF-to-blood ratio was achieved. Tracer studies reliably predicted the therapeutic dose to the CSF. Radioimmunoconjugates targeting GD2 may have clinical utility in the treatment of CNS/LM malignancies.

New agents for intrathecal administration

Intrathecal administration of chemotherapy, with or without radiation therapy, is the primary treatment modality for the prevention and treatment of central nervous system (CNS) metastases in patients with leukemia or lymphoma. Although this treatment strategy has been very effective for patients with hematological malignancies, currently available intrathecal agents are relatively ineffective for patients with neoplastic meningitis resulting from an underlying solid or CNS tumor effective. This article provides an overview of some of the practical considerations and limitations associated with intrathecal chemotherapy, and is followed by a comprehensive review of some of the preclinical and early phase clinical trials of novel anticancer agents and treatment strategies using the intrathecal route.

Neoplastic meningitis from systemic malignancies: diagnosis, prognosis and treatment

Long-term survival is occasionally observed in patients with neoplastic meningitis (NM) accompanying breast cancer (13% one-year and 6% 2-year survival), melanoma, and lymphoma, but in general the survival of most patients is short and averages only 3 to 4 months. The incidence of NM appears to be increasing, in part due to earlier detection by magnetic resonance imaging (MRI), and in part due to development of more effective therapies for systemic cancer, which has resulted in a larger subset at risk for late-stage development of this complication. Survival of NM patients is negatively affected by concomitant progression of systemic disease despite multiple prior therapies. However, there are certain prognostic factors that have been identified as "favorable" in retrospective series, including age less than 60 years, long symptom duration, controlled systemic disease, Karnofsky performance status (KPS) > or =70, lack of encephalopathy or cranial nerve deficits, low initial cerebrospinal fluid (CSF) protein level, history of breast primary tumor, and lack of evidence of CSF compartmentalization or bulky meningeal disease as determined by CSF flow studies. Standard treatment has traditionally involved radiotherapy (RT) to sites of symptomatic or bulky disease, as detected by neuroimaging, and in selected patients, the administration of intrathecal, intraventricular, or systemic chemotherapy. However, treatment remains palliative and many patients and physicians choose supportive care only. Future hope is provided by studies that have improved our understanding of the disease pathogenesis, have identified prognostic variables associated with outcome, and have provided new therapeutic approaches, such as administration of high-dose systemic chemotherapy and investigations of novel therapeutic agents.

Improving the outcome of patients with leptomeningeal cancer: new clinical trials and experimental therapies

Current therapy for leptomeningeal metastases is predominantly palliative. In an effort to improve disease control and patient outcome, new strategies are being developed to target the cerebrospinal space. These include new intrathecal formulations of systemic chemotherapy as well as the development of radiolabeled immunoconjugates and antitumor antibodies. Furthermore, there is debate as to the optimal strategy of drug delivery for leptomeningeal tumor.

Distribution of intraventricularly administered antiamyloid-beta peptide (Abeta) antibody in the mouse brain

There is considerable interest in utilizing the intracerebroventricular (icv) route of administration of antibodies in the brain for various studies and for the therapy of malignancies, but very little is known about the anatomic extent of distribution of the antibody in brain after injection into the third ventricle. To explore the potential for icv administration of antiamyloid-beta peptide (Abeta) in reducing Abeta toxicity in brain in Alzheimer's disease, we first mapped the time course and path of transit of horseradish peroxidase (HRP)-labeled antibody. The results show that, after a single injection into the mouse third venticle, the HRP-labeled antibody is localized within the microvasculature, first that of the corticohippocampal region close to the site of injection at 3 hr. By 24 hr, the antibody is distributed throughout the hippocampus and frontoparietal cortex close to the injection site, as well as in the deep and outer cerebral cortex and cerebellar cortex remote from the injection site. The injected antibody is almost entirely removed by 4 days. Therefore, the antibody had diffused throughout all the brain by 24 hr, showing the feasibility of small quantities of anti-Abeta antibody infused into the third ventricle to reach extracellular epitopes throughout the brain parenchyma rapidly.

Monoclonal antibody-based therapy of neuroblastoma

The curative potential of mAbs in the treatment of patients with metastatic neuroblastoma is increasingly evident. The idiotype network appears to represent one component of a complex mechanism for success with mAb-based immunotherapy. Ongoing strategies to modify or reconstruct mAbs, to engage them with cytokines, or to unite them with T cells open new avenues for harnessing the unique forces of the immune system against some of the most deadly pediatric cancers.