Leptomeningeal Carcinomatosis Medication

Updated: Jun 24, 2016
  • Author: Michael J Schneck, MD, MBA; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Medication

Medication Summary

Chemotherapy is best administered intrathecally so that chemotherapeutic agents, which are usually hydrophilic, do not encounter the blood-brain barrier and easily reach tumor cells in the CSF or leptomeninges. The preferred route of administration is through an implanted subcutaneous reservoir (eg, Rickham or Ommaya reservoir) and ventricular catheter rather than LP, for 4 reasons. First, intraventricular injection through an Ommaya reservoir is easy and ensures entry into the CSF. Second, when injected into the ventricle, the drug follows normal CSF flow and thus reaches all parts of the CSF space. Third, repetitive LPs are arduous and painful for the patient. Fourth, about 10-15% of LPs do not deliver all of the drug intended to reach the subarachnoid space.

CSF flow abnormalities are common in patients with increased ICP and hydrocephalus, and 70% of patients with LC have ventricular outlet obstructions, abnormal spinal canal flow, or impaired flow over the cortical convexities, but these can be reversed with local radiation therapy. A CSF-flow study is recommended for all patients at the initiation of intrathecal chemotherapy, and such therapy should be deferred if an obstruction is noted. Systemic therapy can be useful if the blood-brain barrier already has been disrupted or if the chemotherapeutic agent is lipid soluble.

Methotrexate (MTX), cytarabine (Ara-C), and thiotepa are routinely administered intrathecally for leptomeningeal carcinomatosis. Additionally, several case reports have shown improved prognosis and decreased progression of LC following intrathecal trastuzumab. [9, 38, 39, 40]

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Chemotherapeutic agents

Class Summary

These agents inhibit cell growth and proliferation.

Methotrexate (Folex PFS, Rheumatrex)

Mainstay of treatment. Because meningeal infiltration interferes with drug clearance, CSF concentrations can be unpredictable. Monitor and maintain concentration near 10-6 M, and coadminister with folinic acid and hydrocortisone if necessary.

Cytarabine (Cytosar-U)

Second-line agent used if MTX not tolerated or ineffective. Not effective for solid tumors but useful in leukemic and lymphomatous meningitis. Half-life longer in CSF than serum. Sustained-release form available in United States; extends half-life to >140 h.

Thiotepa

Third-line agent that acts as an alkylating agent. Intrathecal administration is an off-label use in the United States. It is cleared from CSF within minutes and has survival curves similar to those of methotrexate (MTX) with less neurologic toxicity (most common being transient limb paresthesias). Unlike MTX, no antidote for resulting myelosuppression is available. Causes cross-linking of DNA strands, inhibition of RNA, DNA, and protein synthesis, and thus cell proliferation.

Trastuzumab (Herceptin)

Off-label intrathecal (IT) administration of trastuzumab has been described in several case reports. Trastuzumab is a monoclonal antibody that inhibits growth of tumor of tumor cells that overexpress HER2. It is an effective systemic treatment of breast cancer, and as such, the potential use of IT administration for LC secondary to breast cancer has shown improved prognosis and decreased progression in several case reports.

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