To evaluate the safety and efficacy of trimetrexate glucuronate with leucovorin protection in patients with Pneumocystis carinii pneumonia (PCP) who are refractory to or have demonstrated severe or life-threatening toxicities to standard therapies (e.g., TMP/SMX or parenteral pentamidine).

Patients receive intravenous infusions of trimetrexate glucuronate and leucovorin for 21 days. Leucovorin is continued for 3 additional days after discontinuation of trimetrexate glucuronate. Patients are followed for 1 month.

Inclusion Criteria

Concurrent Medication:

Allowed:

• Myelosuppressive or nephrotoxic agents at the discretion of the treating physician.

Patients must have:

• Pneumocystis carinii pneumonia (PCP) confirmed within 15 days prior to study entry.
• Serious intolerance and/or resistance to standard therapies (such as trimethoprim/sulfamethoxazole and parenteral pentamidine) during the course of therapy for the current episode of PCP, or a documented history of such intolerance during a prior episode.
• Consent of parent or guardian if less than 18 years of age.

NOTE:

• Pregnant women may enroll after the physician and patient have discussed the potential benefit versus risk.

Exclusion Criteria

Patients with the following prior conditions are excluded:

History of Type I hypersensitivity (i.e., urticaria, angioedema, or anaphylaxis), exfoliative dermatitis, or other life-threatening reactions due to trimetrexate glucuronate.