Advances in the treatment of multiple myeloma: the role of thalidomide

Efficacy of single-agent bortezomib vs. single-agent thalidomide in patients with relapsed or refractory multiple myeloma: a systematic comparison

OBJECTIVE

To conduct a systematic review of the efficacy of single-agent bortezomib vs. single-agent thalidomide in patients with relapsed/refractory multiple.

METHODS

Publications in English from 1966 to June 2005 (MEDLINE, EMBASE, Cochrane library), publication reference lists, Janssen-Cilag data-on-file and abstracts from recent multiple myeloma conferences were reviewed. Prospective studies containing at least a single arm of either treatment group with n> or =30 were included. Studies adding dexamethasone for non-responders were excluded. Statistical pooling was performed for response rate and overallsurvival.

RESULTS

One bortezomib study (n = 333, NEJM 2005, 352; 2487-98) and 15 thalidomide (n = 1007) studies met these criteria and were included. Patient baseline characteristics including age, gender, IgG : IgA, disease duration and beta-2 microglobulin were well matched except that 48% of bortezomib patients had received prior thalidomide. Response rate, defined as serum M-protein reduction > or =50%, was 53% for patients receiving bortezomib vs. 32% for thalidomide (P < 0.001, n = 10 studies). Response rate determined by European Group for Blood and Marrow Transplantation (EBMT) criteria was 41% for patients receiving bortezomib vs. 22% for thalidomide (P < 0.001, n = 4 studies).

CONCLUSION

Bortezomib was associated with a significantly higher response rate and complete remission rate using both M-protein and EBMT criteria.

Activation of the endoplasmic reticulum stress pathway is associated with survival of myeloma cells

The endoplasmic reticulum (ER) is an organelle in which proteins are modified. When unfolded proteins accumulate in the ER under various stresses, ER stress (ERS) pathways, including the induction of chaperones, are activated to protect the cell. However, when ERS is excessive, the cell undergoes apoptosis. This study investigated ERS in multiple myeloma cells (MMCs) because they contain a well-developed ER due to M-protein production. The myeloma cell line 12-PE underwent apoptosis via caspase-3 after treatment with thapsigargin (thap), an ERS inducer, while another cell line, U266, did not. To understand the mechanism regulating this heterogeneity, the induction of chaperones by thap was analysed. Chaperones were up-regulated in U266 cells but down-regulated in 12-PE cells, suggesting that chaperones contribute to cell survival under ERS. Analysis of XBP-1, a transcriptional inducer of chaperones, in freshly isolated MMCs from 22 myeloma cases revealed 10 cases with active XBP-1, who also showed significantly poorer survival (p < 0.05), suggesting that chaperone expression protects MMCs from apoptosis, thereby allowing tumor cell expansion. These results suggest that MMCs are subjected to ERS under certain circumstances and that chaperones are induced to protect the cells against such ERS. Inhibition of chaperones could be a new target for myeloma therapy.

Thalidomide: an old drug with new clinical applications

Thalidomide has several targets and mechanisms of action: a hypnosedative effect, several immunomodulatory properties with an effect on the production of TNF-alpha and the balance between the different lymphocyte subsets and an antiangiogenic action. Thalidomide has been used in several cutaneous inflammatory disorders (e.g., erythema nodosum leprosum in lepromatous leprosy, cutaneous lupus erythematosus and severe aphtosis), cancers (e.g., relapsed/refractory multiple myeloma, malignant melanoma and systemic signs in cancer) and inflammatory conditions (e.g., Crohn's disease and rheumatoid arthritis). Several side effects are associated with thalidomide. Some are major, such as teratogenicity, peripheral neuropathy and deep vein thrombosis. Somnolence and rash are frequently reported when thalidomide is used at higher doses as an anticarcinogenic agent and can lead to dose reduction or treatment discontinuation depending on severity. Minor side effects include abdominal pain and endocrine disturbances. To prevent the teratogenicity, use of thalidomide is strictly controlled in western countries with close adherence to a birth control programme. Close monitoring for early development of peripheral neuropathy is also recommended.

Phase I and pharmacokinetic study of thalidomide with carboplatin in children with cancer

PURPOSE

Tumor growth and metastasis is believed to depend on the tumor's ability to induce neovascularization. Recent studies have indicated that thalidomide inhibits angiogenesis. We performed a phase I and pharmacokinetic study of thalidomide with carboplatin in children with refractory solid tumors.

PATIENTS AND METHODS

Carboplatin was administered as a single intravenous dose once every 21 days at a target area under the concentration-time curve of 6 mg/mL.min. Thalidomide was administered daily by mouth. The initial dose level was 100 mg/m(2)/d with intrapatient dose escalation to a maximum dose of 300 mg/m(2)/d. The next cohort of patients started at a dose of 300 mg/m(2)/d, with intrapatient dose escalation to a maximum dose of 500 mg/m(2)/d. Standard response and adverse event criteria were used. Serial blood samples for thalidomide pharmacokinetics studies were obtained after the first dose.

RESULTS

Twenty-two patients received 56 cycles of therapy. The maximum tolerated thalidomide dose was 400 mg/m(2)/d. The dose-limiting toxicity was somnolence. There were no objective responses. Thalidomide's apparent clearance was 55 +/- 16 mL/min/m(2) and the terminal half-life was 5.9 +/- 2.8 hours. There was no evidence of dose-dependent pharmacokinetics in the narrow range studied.

CONCLUSION

Thalidomide at a dose of 400 mg/m(2)/d can be safely administered to children with solid tumors in combination with carboplatin. Somnolence is the major toxicity. In addition, we have characterized the pharmacokinetic behavior of thalidomide in children. This study can serve as the basis for future investigation of thalidomide as an anticancer agent in children.

The Generation and Anti-Myeloma Activity of a Chimeric Anti-CD54 Antibody, cUV3

Despite new treatment options, including autologous and allogeneic stem cell transplants, multiple myeloma remains an incurable disease. The authors developed and characterized a murine anti-human ICAM-1 (CD54) monoclonal antibody, UV3, which is highly effective in SCID mice with advanced human myeloma xenografts (SCID/ARH-77). To improve the effector functions and pharmacokinetic parameters and to reduce its immunogenicity in humans, the authors engineered this monoclonal antibody into a mouse/human IgG1kappa chimeric (c) antibody, cUV3. Following coexpression and purification of the genetically spliced heavy and light chain constructs, the authors compared cUV3 and UV3 in various in vitro assays, including relative cell-binding affinities and effector functions, namely antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. The authors compared their in vivo retention times and biodistribution patterns in normal mice. In each assay, the authors found that cUV3 was essentially equivalent to UV3. Finally, these antibodies were tested in a SCID/ARH-77 model of advanced myeloma, with daily treatments of 4 mug/g for 4 consecutive days commencing 14 days after tumor cell inoculation. cUV3 was at least as effective as UV3; 40% and 20% of the mice, respectively, were cured, with no sign of disease at day 150. The authors intend to evaluate the efficacy of cUV3 further in SCID/ARH-77 mice using other doses and dosing schedules to try to improve the cure rate. Eventually, they hope to test the efficacy of cUV3 in patients with multiple myeloma.