Intrathecal radioisotopes for the treatment of brain tumors

Carcinomatous meningitis: Leptomeningeal metastases in solid tumors

Leptomeningeal metastasis (LM) results from metastatic spread of cancer to the leptomeninges, giving rise to central nervous system dysfunction. Breast cancer, lung cancer, and melanoma are the most frequent causes of LM among solid tumors in adults. An early diagnosis of LM, before fixed neurologic deficits are manifest, permits earlier and potentially more effective treatment, thus leading to a better quality of life in patients so affected. Apart from a clinical suspicion of LM, diagnosis is dependent upon demonstration of cancer in cerebrospinal fluid (CSF) or radiographic manifestations as revealed by neuraxis imaging. Potentially of use, though not commonly employed, today are use of biomarkers and protein profiling in the CSF. Symptomatic treatment is directed at pain including headache, nausea, and vomiting, whereas more specific LM-directed therapies include intra-CSF chemotherapy, systemic chemotherapy, and site-specific radiotherapy. A special emphasis in the review discusses novel agents including targeted therapies, that may be promising in the future management of LM. These new therapies include anti-epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors erlotinib and gefitinib in nonsmall cell lung cancer, anti-HER2 monoclonal antibody trastuzumab in breast cancer, anti-CTLA4 ipilimumab and anti-BRAF tyrosine kinase inhibitors such as vermurafenib in melanoma, and the antivascular endothelial growth factor monoclonal antibody bevacizumab are currently under investigation in patients with LM. Challenges of managing patients with LM are manifold and include determining the appropriate patients for treatment as well as the optimal route of administration of intra-CSF drug therapy.

Leptomeningeal metastases from solid malignancy: a review

Leptomeningeal metastases (LMM) consist of diffuse involvement of the leptomeninges by infiltrating cancer cells. In solid tumors, the most frequent primary sites are lung and breast cancers, two tumors where the incidence of LMM is apparently increasing. Careful neurological examination is required to demonstrate multifocal involvement of the central nervous system (CNS), cranial nerves, and spinal roots, which constitute the clinical hallmark of the disease. Cerebro-spinal fluid (CSF) analysis is almost always abnormal but only a positive cytology or demonstration of intrathecal synthesis of tumor markers is diagnostic. T1-weighted gadolinium-enhanced sequence of the entire neuraxis (brain and spine) plays an important role in supporting the diagnosis, demonstrating the involved sites and guiding treatment. Radionuclide CSF flow studies detect CSF compartmentalization and are useful for treatment planning. Standard therapy relies mainly on focal irradiation and intrathecal or systemic chemotherapy. Studies using other therapeutic approaches such as new biological or cytotoxic compounds are ongoing. The overall prognosis remains grim and quality of life should remain the priority when deciding which treatment option to apply. However, a sub-group of patients, tentatively defined here, may benefit from an aggressive treatment.

Principles of radiotherapy of neoplastic meningosis

Neoplastic meningosis can be a complication of a tumor originating in the brain or the meninges, or it can be a complication of a solid tumor elsewhere that has metastasized to the leptomeninges. The therapeutic dilemma for a radiation oncologist is that neoplastic meningosis involves the entire neuraxis and, as a consequence, ideally, the entire neuraxis should be radiated. However, delivering the necessary radiation dose to the entire neuraxis may be associated with considerable neurologic or bone marrow toxicity. Radiotherapy of neoplastic meningosis can be performed by external beam radiation or by intrathecal injection of radioactive nuclides or radiolabeled monoclonal antibodies. Intrathecal radiation has the theoretical advantage that treatment is directed towards the entire neuraxis with limited irradiation outside the neuraxis. In practice, intrathecal radiation is still under investigation and subject to some limitations and toxicities. Indications and techniques for external beam radiation may range from either therapeutic or elective cranial or craniospinal radiation to palliative involved-field radiation. Patients with neoplastic meningosis are frequently treated with a combination of radiation and chemotherapy, and/or may have been irradiated to the nervous system in the past. Both are well known risk factors for radiation damage to the nervous system. In general, current treatment protocols focus on the development of combination chemotherapy programs and reduction of the radiation dose to minimize toxicity and/or to improve tumor control.

The potential of targeted radiotherapy in the treatment of central nervous system leukaemia

We describe the results of clinical studies investigating the role of monoclonal antibody (MoAb) targeted radiotherapy in the treatment of central nervous system (CNS) leukaemia. Seven children, aged 3-16 years, in second or subsequent meningeal relapse of acute lymphoblastic leukaemia (ALL), have been treated. Each patient received a single injection into the cerebrospinal fluid (CSF) of between 629 and 1,702 MBq of 131-Iodine (131I) conjugated to MoAb HD37 (CD19, n = 2), WCMH 15.14 (CD10, n = 4) or both antibodies (n = 1). One patient underwent a course of repeated targeted therapy following his initial treatment. Acute toxicity was manifest in five patients by a transient aseptic meningitis. Myelosuppression was observed in four children. Pharmacokinetic studies investigated whole body, blood and CSF clearance of radioisotope. Progressively more rapid systemic clearance of 131I was noted in the patient receiving repeated therapy, indicating the development of the human anti-mouse Ig (HAMA) response. Dosimetric studies revealed a radiation dose to the red bone marrow of between 0.6 and 2.2 Gy. The dose to the subarachnoid CSF was between 12.2 and 25.3 Gy, over six times higher than that to the surface tissue of the brain and spinal cord and between 40 and 140 times higher than that to the whole brain. In all but one patient, a transient complete response, in terms of disappearance of lymphoblasts from the CSF, was observed. These studies demonstrate the feasibility of targeted radiotherapy in CNS ALL.(ABSTRACT TRUNCATED AT 250 WORDS)

A pilot study of monoclonal antibody targeted radiotherapy in the treatment of central nervous system leukaemia in children

A pilot study was performed to investigate the toxicity, pharmacokinetics and therapeutic effect of intrathecally administered radiolabelled monoclonal antibody (MAb) in patients with meningeal acute lymphoblastic leukaemia (ALL). Six children aged 3-16, in second or subsequent central nervous system (CNS) relapse of ALL, received between 629 and 1480 MBq of 131Iodine conjugated to either MAb HD37 (CD19, n = 2) or WCMH15.14 (CD10, n = 4). Conjugate was administered as a single injection either via an Ommaya reservoir (n = 4) or by lumbar puncture (n = 2). Acute toxicity was manifest by headache (n = 4), nausea and vomiting (n = 4) and pyrexia (n = 2). All acute symptoms resolved within 72 h. Transient myelosuppression occurred in three patients. Pharmacokinetic studies included investigation of whole body, blood and CSF clearance of isotope. 131I was seen to clear from the CSF by biexponential kinetics. Five patients responded to therapy. In four, the CSF became clear of blast cells at both 2 and 4 weeks following antibody injection, but evidence of relapse was seen at 6 weeks. The fifth patient, with blast cells present on a cytospin preparation, responded to therapy over an 8-week period but relapsed at 12 weeks. This study demonstrates the potential of targeted radiotherapy in CNS ALL, but further studies are necessary to increase the length of remission.

Cerebral aneurysms following radiotherapy for medulloblastoma

Three patients, two males and one female aged 21, 14, and 31 years, respectively, developed cerebral saccular aneurysms several years after undergoing radiotherapy for cerebellar medulloblastoma at 2, 5, and 14 years of age, respectively. Following surgery, all three received combined cobalt-60 irradiation and intrathecal colloidal radioactive gold (198Au) therapy, and died from rupture of the aneurysm 19, 9, and 17 years after the radiotherapy, respectively. Autopsy examination revealed no recurrence of the medulloblastoma, but widespread radiation-induced vasculopathy was found at the base of the brain and in the spinal cord, and saccular aneurysms arose from the posterior cerebral arteries at the basal cistern or choroidal fissure. The aneurysms differed from the ordinary saccular aneurysms of congenital type in their location and histological features. Their locations corresponded to the areas where intrathecally administered colloidal 198Au is likely to pool, and they originated directly from a segment of the artery rather than from a branching site as in congenital saccular aneurysms. It is, therefore, concluded that the aneurysms in these three patients were most likely radiation-induced.

A pilot study of 131I monoclonal antibodies in the therapy of leptomeningeal tumors

A pilot study was performed to investigate the toxicity and therapeutic effect of radiolabeled antibody administered intrathecally in patients with leptomeningeal tumors. Five patients who failed conventional therapy received between 11 mCi and 40 mCi of radiolabeled antibody. The choice of antibody varied depending on the immunophenotype of the tumor. Therapy was well tolerated generally, with minimal acute toxicity. Four of five patients achieved an objective response to treatment that has been sustained for a period varying from 7 months to 2 years. No clinical signs of chronic toxicity have been observed in patients 1 and 2 years after therapy.

Intracranial tumors with risk of dissemination in neuroaxis

The experience of the Radiotherapy Service, Clínica Puerta de Hierro, Madrid (Spain), in the treatment of intracranial tumors with risk of neural axis dissemination is analyzed. In 15 years (1964-1979) 415 primary central nervous system tumors were studied and treated; 67 corresponded to tumors with risk of meningeal dissemination. Clinical dissemination in cerebrospinal fluid was proven in 14 patients. The actuarial survival of 10 years for patients with neural axis dissemination, without prophylactic treatment to the neuroaxis, is 14% with an average survival of 10.5 months. In approximately 20% of meduloblastomas, ependymal and pineal region tumors, meningeal metastases at some distance from the primary tumor can take place. Patients at risk wtih these types of neoplasia must be identified, and an adequate radical therapeutic focus devised, not only for the primary tumor, but also for the risk of dissemination.

Cerebellar medulloblastoma: results of a new method of radiation treatment

Nine patients with medulloblastoma were referred to the Radiation Oncology Section at the University of Chicago from 1966 to 1976. In all patients, the tumor was situated in the posterior cranial fossa, projecting from the cerebellum into the fourth ventricle. After partial tumor resection and histological diagnosis, radiation treatment was instituted: a localized dose of 1000 rad to the posterior fossa through lateral opposing ports and a total dose of 4000-5000 rad through the "hockey-stick" port to the entire CNS. With this treatment, 9 patients yielded actuarial 3- and 5-year survival rates of 88% and 73%, respectively. Five of the patients possessed no history of neurologic or spinal growth deficits after treatment. Two patients had a slight retardation of spinal growth. The remaining patients had presented symptoms of a tumor mass in the posterior fossa for a period of over 8 months prior to treatment. They were found at craniectomy to have diffuse intracranial tumor involvement, and their survival times deteriorated rapidly. The "hockey-stick" port provided a uniform distribution of radiation exposure to the entire brain and spine. It was simple to use and posed little inconvenience to patients in the pediatric age group.

Remission maintenance therapy for meningeal leukaemia: intrathecal methotrexate and dexamethasone versus intrathecal craniospinal irradiation with a radiocolloid

Thirty-two patients with meningeal leukaemia who achieved meningeal remission with intrathecal methotrexate (MTX) plus dexamethasone (DMT) were entered in a randomized study of two maintenance treatments: (a) I6 patients received intermittent intrathecal doses of MTX plus DMT, and (b) I6 patients received intermittent intrathecal doses of radioactive chromic phosphate (CROP). The population and clinical characteristics of the cases assigned to each maintenance regimen were similar. The duration of meningeal remission was 55-600 + d (median 550 d) for the MTX and DMT group and 56-555 d (median 360 d) for the CROP group. There was no statistical difference (P greater than 0.05) between the curves of the two groups. Intrathecal CROP seems to be as effective as intrathecal MTX plus DMT as maintenance treatment for intrathecal MTX plus DMT induced meningeal remission. Further uses of this compound should be explored but it seems to be dangerous to administer it by lumbar puncture.

Therapeutic irradiation of the central nervous system using intrathecal 90Y--DTA

The erdication of established neuroleukaemia is often difficult, and with subsequent relapses even harder. The use of an intrathecally-injected beta emitting isotope has the advantage of preserving the bone-marrow of the vertebral column and cranium whislt irradiating the meninges. The value of intrathecal 90Y-DTPA(diethylene-triamine penta-acetic acid) has been investigated in nine patients with neuroleukaemia or CNS involvement in malignant lymphoma. Measurements of retention of the isotope in the whole body, spinal, and intracranial subarachnoid spaces have been made, together with blood levels, and are reported. The clinical results are presented. In three out of five evaluable patients 90Y-DTPA failed to maintain a chemotherapy-induced CNS remission and in two out of two evaluable patients malignant cells were not dispersed from the CNS with a single intrathecal injection of 90Y-DTA. It is concluded, therefore, that with this agent and the doses used no useful clinical result is gained.

Combined modality therapy for intracranial tumors

Three types of tumor (supratentorial astrocytoma, medulloblastoma, and craniopharyngioma), each requiring a fundamentally different therapeutic approach, will be used to illustrate the principles and practice of combined treatment in this field. The role of radiotherapy and ways of enhancing the effect of irradiation will be considered. Attention will be given to adjuvant chemotherapy and to multiple drug regimes. Reference will be made to an early effort at immunotherapy following the initial reduction of tumor cell load by surgery and irradiation.