High-dose methotrexate for intraocular lymphoma

Intraocular lymphoma (IOL) frequently coexists with primary central nervous system lymphoma(PCNSL). We sought to determine the efficacy of high-dose methotrexate (MTX) alone in patients with IOL. We also sought to determine whether micromolar levels of MTX could be achieved in the aqueous and vitreous humor of the eye after i.v. administration of the drug.

Nine patients with concurrent PCNSL and IOL or isolated IOL were treated with MTX alone. All patients were treated with i.v. 8 g/m(2) MTX. MTX concentrations in serum, aqueous humor, and vitreous humor were obtained in seven of nine patients with IOL and in one additional patient with PCNSL but no evidence of IOL.

Micromolar concentrations of MTX were present in both ocular chambers 4 h after completion of the infusion in eight of eight patients. Levels of MTX were lower in the vitreous humor compared with the aqueous humor in five of six patients in whom both chambers were assayed. Initial response of IOL to MTX was demonstrated by seven of nine patients (six complete responses and one partial response), whereas two patients had persistent IOL despite achievement of micromolar concentrations of MTX. In the patients with concurrent PCNSL and IOL, seven of seven had complete responses in the brain after treatment with MTX. Three of seven patients with initial response of IOL experienced relapse in the eye requiring orbital radiation, and four of nine patients had sustained response of IOL to MTX.

A subset of patients with IOL may experience sustained remission when treated with high-dose i.v. MTX alone. Although micromolar MTX concentrations are present in the eye 4 h after infusion, the lower concentration achieved in vitreous humor may contribute to persistence of IOL.