Methods of administering monomethyl fumarate and prodrugs thereof having reduced side effects

A method of treating a disease in a population of patients in need of such treatment, comprising:

• (a) testing each of the patients for a propensity for a deficiency in tissue glutathione S-transferase theta 1 enzyme (GSTT1) levels;
• and thereafter performing one of (b) or (c);
• (b) administering a compound selected from monomethyl fumarate (MMF), a prodrug of monomethyl fumarate, and combinations thereof only to those patients exhibiting little or no propensity for a deficiency in tissue GSTT1 levels;
• or
• (c) administering a compound selected from monomethyl fumarate (MMF), a prodrug of monomethyl fumarate, and combinations thereof to the patients regardless of their enzyme level propensity testing results, and during the treatment of the disease, periodically testing blood lymphocyte concentrations in each of the patients at a predetermined time interval length that is based on each patient's own enzyme level propensity testing result.

A method of optimizing the safety of treatment of a compound selected from MMF, a prodrug of MMF and combinations thereof, in a patient in need of such treatment, comprising:

• testing the patient for a propensity for a deficiency in tissue glutathione S-transferase theta 1 enzyme (GSTT1) levels;
• wherein, if said testing shows little or no propensity for a deficiency in tissue GSTT1 levels:
• administering to the patient a therapeutically effective amount of the compound;
• and
• periodically testing blood lymphocyte concentration in the patient at a predetermined time interval length that is based on the enzyme level propensity testing result.