Comparison of serum and cerebrospinal fluid levels of methotrexate in man during high-dose chemotherapy for aggressive non-Hodgkin's lymphoma

Central Nervous System Prophylaxis for Aggressive B-cell Lymphoma: Who, What, and When?

Central nervous system (CNS) relapse of aggressive B-cell lymphoma is a rare but serious complication with poor survival. Different approaches have been used to define risks factors for CNS relapse and establish prophylactic measures. Although patients with low or intermediate risk of CNS relapse should not undergo special diagnostic or therapeutic measures, CNS MRI as well as cytology and flow cytometry of the cerebrospinal fluid are suggested for high-risk patients (and patients with testicular involvement) at diagnosis, and prophylactic high-dose methotrexate in patients without proven CNS involvement. Future risk and treatment models may include molecular features and new treatment options.

Managing CNS disease in adults with acute lymphoblastic leukemia

The central nervous system (CNS) is an important site of involvement by acute lymphoblastic leukemia (ALL) in adults. The prevalence is sufficiently high that prophylactic treatment is routinely given to this sanctuary site in order to eradicate occult disease that might otherwise lead to a relapse. A lumbar puncture should be routinely performed in all newly diagnosed patients with ALL. The risks of CNS leukemia vary by phenotype and genotype. Preventive treatment of the CNS during post-remission therapy has become an integral part of all current ALL treatment protocols. Most treatment regimens combine multiple doses of intrathecal chemotherapy with high-dose systemic methotrexate and/or cytarabine. Cranial irradiation is less commonly used for prophylaxis but is still the most effective treatment for overt CNS leukemia. Recurrences within the CNS usually coincide with or predict soon afterwards for systemic relapse in the marrow and blood.

Long-term survival of a patient with leptomeningeal involvement by nasopharyngeal carcinoma after treatment with high-dose intravenous methotrexate

BACKGROUND

Nasopharyngeal carcinoma with leptomeningeal involvement is rare and typically has poor prognosis.

METHODS AND RESULTS

We present a case report of a patient with nasopharyngeal carcinoma who was treated with high-dose intravenous methotrexate and remains asymptomatic and without clinical evidence of disease 6 years later.

CONCLUSIONS

Systemic high-dose methotrexate should be evaluated in the treatment of advanced nasopharyngeal carcinoma with central nervous involvement.

Pharmacokinetic considerations in the treatment of CNS tumours

Despite aggressive therapy, the majority of primary and metastatic brain tumour patients have a poor prognosis with brief survival periods. This is because of the different pharmacokinetic parameters of systemically administered chemotherapeutic agents between the brain and the rest of the body. Specifically, before systemically administered drugs can distribute into the CNS, they must cross two membrane barriers, the blood-brain barrier (BBB) and blood-cerebrospinal fluid (CSF) barrier (BCB). To some extent, these structures function to exclude xenobiotics, such as anticancer drugs, from the brain. An understanding of these unique barriers is essential to predict when and how systemically administered drugs will be transported to the brain. Specifically, factors such as physiological variables (e.g. blood flow), physicochemical properties of the drug (e.g. molecular weight), as well as influx and efflux transporter expression at the BBB and BCB (e.g. adenosine triphosphate-binding cassette transporters) determine what compounds reach the CNS. A large body of preclinical and clinical research exists regarding brain penetration of anticancer agents. In most cases, a surrogate endpoint (i.e. CSF to plasma area under the concentration-time curve [AUC] ratio) is used to describe how effectively agents can be transported into the CNS. Some agents, such as the topoisomerase I inhibitor, topotecan, have high CSF to plasma AUC ratios, making them valid therapeutic options for primary and metastatic brain tumours. In contrast, other agents like the oral tyrosine kinase inhibitor, imatinib, have a low CSF to plasma AUC ratio. Knowledge of these data can have important clinical implications. For example, it is now known that chronic myelogenous leukaemia patients treated with imatinib might need additional CNS prophylaxis. Since most anticancer agents have limited brain penetration, new pharmacological approaches are needed to enhance delivery into the brain. BBB disruption, regional administration of chemotherapy and transporter modulation are all currently being evaluated in an effort to improve therapeutic outcomes. Additionally, since many chemotherapeutic agents are metabolised by the cytochrome P450 3A enzyme system, minimising drug interactions by avoiding concomitant drug therapies that are also metabolised through this system may potentially enhance outcomes. Specifically, the use of non-enzyme-inducing antiepileptic drugs and curtailing nonessential corticosteroid use may have an impact.

Phase II multicenter study of brief single-agent methotrexate followed by irradiation in primary CNS lymphoma

PURPOSE

To assess, in a multi-institutional setting, the impact on relapse, survival, and toxicity of adding two cycles of intravenous methotrexate to cranial irradiation for immunocompetent patients with primary CNS lymphoma.

PATIENTS AND METHODS

Forty-six patients with a median age of 58 years and Eastern Cooperative Oncology Group performance status 0 to 3 were entered onto this phase II study. The protocol consisted of methotrexate 1 g/m(2) on days 1 and 8 followed by cranial irradiation on day 15. A whole-brain dose of 45 Gy was followed by a boost of 5.4 Gy. Intrathecal chemotherapy and spinal irradiation were given only to patients for whom cytologic examination of CSF was positive for CNS lymphoma. The median follow-up time was 36 months, with a minimum potential follow-up of 12 months.

RESULTS

Median survival was 33 months, with 2-year probability of survival 62% +/- 15% (95% confidence interval). Twenty patients have relapsed. The predominant site of relapse was the brain. Neither performance status nor age was found to influence survival. Six patients developed a dementing illness at a median of 16 months after treatment, and three of these died as a consequence.

CONCLUSION

A brief course of intravenous methotrexate before cranial irradiation is associated with 2-year and median survival rates superior to those reported for radiotherapy alone and similar to more intensive combined-modality regimens. Neurotoxicity remains an important competing risk for these patients.

Current diagnosis and treatment of leptomeningeal metastasis

Meningeal metastasis occurs in 3-8% of all cancer patients, producing neurologic morbidity and a high mortality. Diagnosis is best established by the demonstration of malignant cells in the cerebrospinal fluid. However, in patients with known cancer, MR scan with gadolinium may be diagnostic when subarachnoid nodules can be demonstrated in the head or spine. Therapy usually involves radiotherapy to symptomatic sites, often followed by intrathecal chemotherapy. Intrathecal chemotherapy is best delivered by an intraventricular reservoir system but can also be delivered by repeated lumbar puncture. Methotrexate, cytarabine and thiotepa are the most common agents instilled into the subarachnoid space. Their limited efficacy can be explained by their restricted spectrum of antitumor activity. Patients with leptomeningeal metastasis from leukemia, lymphoma or breast cancer tend to respond best and this may, in part, be attributed to the relative sensitivity of these primary tumor types to the agents administered intrathecally. Systemic chemotherapy may prove a more attractive alternative to intrathecal drugs since it can penetrate into bulky disease, reach all areas of the subarachnoid space, and not be restricted by CSF bulk flow. The prognosis for patients with leptomeningeal metastasis is poor, most individuals surviving a median of only about four months. Occasional patients do have prolonged survival and improvement of their neurologic function.

Oral mucositis and salivary methotrexate concentration in intermediate-dose methotrexate therapy for children with acute lymphoblastic leukemia

The relationship between salivary methotrexate (MTX) concentration and severity of oral mucositis after administration of MTX was investigated in six children with acute lymphoblastic leukemia. They received two administrations of MTX at 500 mg/m2 with one third given bolusly and the remainder by 24-hour continuous infusion. No significant difference among patients or administration session was observed in serum MTX concentration. Detectable concentrations of salivary MTX (greater than 0.01 microM) were observed during nine of the ten infusions. A concentration of 0.1 microM or more, apparently lasting at least 12 hours, was observed during one infusion and followed by severe mucositis. During two of the ten infusions for different patients, concentrations of 0.04 to 0.07 microM and 0.02 to 0.04 microM, apparently lasting at least 12 and 18 hours, respectively, were observed, followed by moderate mucositis. During the other seven infusions, either much shorter or no increase in salivary MTX concentration was observed, with only mild or no subsequent mucositis. Analysis by Kendall's rank method showed a statistical correlation between concentration at 6 hours of infusion and severity of oral mucositis. The findings suggest that the early secretion of MTX into saliva has a significant role in the development of oral mucositis in leukemic children.

Methotrexate concentration levels in the cerebrospinal fluid during high-dose methotrexate infusions: an unreliable prediction

In 25 children with lymphoid malignancies, 96 high-dose methotrexate infusions (3 g/m2) with a duration of 24 h have been administered as a part of the treatment schedule. A lumbar puncture was performed to apply methotrexate intrathecally. The moment of lumbar puncture during the infusion was chosen at different times. In 76 of the infusions the concentration of methotrexate in the cerebrospinal fluid and in plasma were determined just prior to the intrathecal administration. From the second to the eighth hour after the initiation of the infusion the concentration of methotrexate in the cerebrospinal fluid and in plasma were determined just prior to the intrathecal administration. From the second to the eighth hour after the initiation of the infusion the concentration of methotrexate in the cerebrospinal fluid appeared to be significantly lower than 16 or 24 h after the initiation of the infusion. Of all samples during the infusions, the plasma concentration varied a tenfold (2-20 X 10(-5) mol/L), but the cerebrospinal fluid concentration of methotrexate varied about a 300-fold (3.5-900 x 10(-8) mol/L). No correlation could be found between the plasma concentration of methotrexate and the cerebrospinal fluid concentration. It is concluded that the methotrexate concentration in the cerebrospinal fluid cannot be predicted by determining the plasma concentration. It takes at least 8 h of infusion before a steady-state concentration of methotrexate is reached in the cerebrospinal fluid. In high-dose methotrexate infusions without intrathecal therapy, the dose of 3 g/m2 is the minimum amount of methotrexate to reach the minimum therapeutic concentration 5 x 10(-7) mol/L) in the cerebrospinal fluid for the treatment of subclinical central nervous system invasion of malignant lymphoid cells. To maintain the minimum therapeutic concentration according to the CxT principle the duration of the infusion should be preferably longer than 24 h.

Effect of dose and repeat intravenous 24 hr infusions of methotrexate on cerebrospinal fluid availability in children with hematological malignancies

This pharmacokinetic study examined the relationship between methotrexate (MTX) dose and drug concentrations in blood and cerebrospinal fluid (CSF) during repeated 24 hr infusions. Two regimens were used: an intermediate dose (ID) of 0.5 g/m2 (7 patients, 23 cycles) and a high dose (HD) of 2.5 g/m2 (8 patients, 39 cycles). Inter-patient variability in the drug concentration was apparent in serum and CSF for both doses. The dispersion was particularly wide in CSF for HD MTX. Considering median values, serum and CSF MTX were linked to dose escalation. Individual CSF/serum drug ratios were not modified by the dose (1.1% for ID MTX versus 1.4% for HD MTX). A potentially cytotoxic drug level in CSF (10(-6) M) was never obtained for ID MTX cycles, but was achieved in 44% of HD MTX cycles: for HD MTX, this corresponded to 88% of patients (7/8). Total body clearance did not modify the degree of CSF MTX passage. A positive, significant correlation (r = 0.62, P less than 0.05) was observed for ID MTX between individual serum and CSF MTX; no such relationship was seen with HD MTX. Individual cycle-to-cycle variations in the MTX concentration were particularly marked in CSF and for HD MTX, without strict concordance with blood levels.