The effects of thalidomide treatment on autoimmune-prone NZB and MRL mice are consistent with stimulation of the central immune system

Lenalidomide alone or lenalidomide plus dexamethasone significantly inhibit IgG and IgM in vitro... A possible explanation for their mechanism of action in treating multiple myeloma

Lenalidomide (len) is an analog of thalidomide (thal), and both are used in the treatment of a diverse group of medical conditions. A common finding in this group is the detection of immunoglobulin in skin lesions, or high levels of immunoglobulin or myeloma protein in serum and urine. While their mechanism(s) of action is not known, the drugs are noted for their ability to modulate monocyte, lymphocyte, and natural killer cell functions; suppression of immunoglobulin synthesis could offer an explanation for their effectiveness in treating multiple myeloma (MM). Our objective was to determine if, on an equimolar basis, thal, len or dexamethasone (dex) could affect pokeweed (PWM)-induced synthesis of IgG, IgM and IL-2. When peripheral blood mononuclear cells were stimulated with PWM, len surpassed thal in suppressing IgM and IgG, and enhancing IL-2. Dex enhanced IgG, and suppressed IL-2. When the stimulated cells were treated with len (an effective promoter of IL-2 and suppressor of IgM and IgG) plus dex (an effective suppressor of IL-2 and enhancer of IgG), the net result was suppression of IgM and IgG. The synthesis of IgM and IgG by putative PWM-stimulated B cell blasts is significantly blocked by len. This suggest that the B-lymphocyte is a targeted cell for len, and that suppression of the synthesis of IgG and IgM could provide an explanation for the mechanism by which len effectively treats MM.

Thalidomide: mechanisms of action

The classification of thalidomide as an orphan drug with anti-inflammatory actions has led to its off-label use in conditions refractory to other medications. Although the observed clinical effects of thalidomide suggest it to have immunomodulatory capabilities, the mechanism of action is unclear. Here we review both the positive and negative studies of thalidomide at the bench in order to improve our understanding of the possible mechanisms of this drug in treating a variety of diseases at the bedside. Studies on the effects of thalidomide on the innate and adaptive immune system as well as tumorigenesis and angiogenesis are discussed.

Thalidomide stimulates splenic IgM antibody response and cytotoxic T lymphocyte activity and alters leukocyte subpopulation numbers in female B6C3F1 mice

Thalidomide has been shown to have antiinflammatory and, more recently, immunomodulating properties, which are beneficial for the treatment of an ever-increasing list of immune related diseases. Although considerable knowledge regarding thalidomide s antiinflammatory properties has been acquired, relatively little is known about its immunomodulating properties in vivo. In this paper, a panel of immune assays was used to evaluate immunomodulation in female B6C3F1 mice treated intraperitoneally for 28 days with thalidomide (30, 100, or 150 mg/kg/day). Spleen antibody forming cell response was significantly enhanced by 37% in mice treated with 150 mg/kg/day, despite an 8% decrease in the percentage of Ig+ B cells. A significant stimulatory trend was observed for the cytotoxic T cell response across thalidomide treatment groups. An evaluation of the spleen leukocyte subpopulations revealed a 23% increase in the absolute number of CD8+ T cells in the 150 mg/kg treatment group and a 9 and 11% decrease in the absolute number of NK cells in both the 100 and 150 mg/kg thalidomide treatment groups, respectively. These findings demonstrate that, in addition to modulating spleen leukocyte numbers, thalidomide also stimulates murine humoral and cellular immune responses in vivo.

[Treatment of recurrent ulceration with low doses of thalidomide. Pilot study in 17 patients]

PURPOSE

Though thalidomide in a dosage of 100 mg/day is the standard treatment for recurrent oral and genital ulcers (OGU), its toxicity would be less important with lower dosage, while its efficacy would be identical. Furthermore, duration of treatment might be a major risk factor for the development of subsequent polyneuropathy. To determine the dosage of thalidomide leading to the best efficacy/toxicity ratio, a pilot study was conducted from 1993 to 1996.

METHODS

Seventeen patients with OGU (mean age: 43 years, sex-ratio: 12:5) were included in the study and presented either recurrent oral ulcerations (8 patients), oro-genital ulcerations (3 patients), Behçet disease (4 patients), or recurrent OGU associated with leukemia (2 patients). The initial dosage of thalidomide was 50 mg/day (1 tablet) for 1 month. If the patient's condition improved, the dosage was reduced to one tablet every other day for 1 month and one tablet every 3 days thereafter. Nerve conduction studies (EMG) were performed at inclusion in the study and every 6 months thereafter.

RESULTS

Among the 17 patients, remission was observed in ten patients within the first month of treatment and the condition of seven patients improved. Complete remission was observed in six patients after a 2-month treatment and in one patient after 4 months. A 200-mg/8 days dosage induced prolonged remission in 12 patients. Among them, ten patients received a 150-mg dosage over 8 days thereafter and disease relapsed in four of them. Among the six patients who received a 100-mg dosage over 8 days, only one relapse was observed. EMG showed a decrease in sensory nerve action potentials in six patients after 8 months and a half on average. Only three patients had to discontinue their treatment due to the occurrence of either paresthesia (2 patients) or areflexia (1 patient). Our study shows that initially a 50-mg/day dose is efficacious in the treatment of OGU and that administration of one tablet every 2 or 3 days is efficacious in more than 60% of the patients to maintain remission.

CONCLUSION

A dosage of 50 mg/day is initially efficacious in most cases, provided that the patient is carefully followed up to allow early detection of potential peripheral neuropathy.