Intrathecal Pemetrexed for Recurrent Leptomeningeal Metastases From Non-small Cell Lung Cancer

This is a single arm clinical trial. The objective of the study is patients with recurrent or progressive leptomeningeal metastases from non-small cell lung cancer after leptomeningeal metastases-related treatment. The regimen of pemetrexed (Alimta, Eli Lilly and Company) is 10/15/20 mg, plus dexamethasone 5 mg, twice per week for 2 weeks, followed by once per week for 2-4 weeks. Pemetrexed and dexamethasone are administrated by intrathecal injection via lumbar puncture. Folic acid and vitamin B12 are administered to reduce the frequency of myelosuppression. Folic acid 200-400 μg is administered orally once daily, prior to the first intrathecal pemetrexed, until 21 days after the last intrathecal pemetrexed. A single dose of vitamin B12 1000 μg is administered by intramuscular injection before the first intrathecal pemetrexed，once per 3 weeks. To detect the pharmacokinetics of intrathecal pemetrexed, the serum and cerebrospinal fluid samples are collected. These samples would be analyzed by spectrometer for drug concentration.

Inclusion criteria

• Patients diagnosed as leptomeningeal metastases from non-small cell lung cancer had been received comprehensive treatment, including intrathecal methotrexate and/or cytarabine, central nervous system radiation therapy, systemic chemotherapy as well as tyrosine-kinase inhibitor drugs.
• Patients diagnosed with recurrent leptomeningeal metastases by positive cerebrospinal fluid cytological examination and persist aggravate symptoms for more than 1 week, or increased intracranial pressure (>300 mmH2O).
• No severe abnormal liver and kidney function; WBC≥2500/mm3, Plt≥60000/mm3;
• No other severe chronic diseases;
• No severe dyscrasia.
• Signed informed consent form.

Exclusion criteria

• Patients with the clinical manifestation of nervous system failure including severe encephalopathy, grade III-IV white matter lesions confirmed by imaging examination, moderate or severe coma, and glasgow coma score less than 9 points;
• Patients with severe nervous system injury related with treatment, such as chemical meningitis;
• Patients who had accepted systemic chemotherapy within two weeks, or new molecular targeted therapeutic drug less than one months;
• Patients with poor compliance, or for other reasons, the researchers considered unsuitable to participate in this clinical study.