Treatment for Multiple Myeloma
As previously described in the section on corticosteroids, high-dose dexamethasone can complicate interpretation of clinical trials by worsening cardiopulmonary toxicity and deaths, especially in the context of thalidomide or lenalidomide, both of which are thrombogenic agents.
Factors that have been implicated to worsen the risk of DVT include the use of high-dose dexamethasone, concomitant erythropoietic growth factors, and concomitant doxorubicin, liposomal doxorubicin, or alkylating agents.
Personal cardiovascular risk factors can also influence the rate of DVT. Various clinical trials have included different DVT prophylaxis measures, including aspirin (81 mg-100 mg a day), warfarin, or low-molecular-weight heparin, but the validity of these measures has not been studied prospectively in a randomized study.[21,22,27,28,29,30,31]
Prospective electrophysiologic monitoring provides no clear benefit over clinical evaluation for the development of clinically significant neuropathy while on thalidomide.
- A prospective randomized study of 351 relapsed patients compared lenalidomide, an analogue of thalidomide, plus high-dose dexamethasone with high-dose dexamethasone plus placebo.
- The lenalidomide combination showed a significantly higher time to tumor progression (11.3 mo vs. 4.7 mo, P < .001) with a 16-month median follow-up, and median OS had not been reached, versus 20.6 months in the placebo group (hazard ratio [HR] = 0.66, 95% confidence interval [CI], 0.45-0.96, P = .03).[Level of evidence: 1iA]
- The lenalidomide-containing arm had more DVT (11.4% vs. 4.6%).
- Similarly, another randomized prospective trial (NCT00179647) of 353 previously treated patients favors the lenalidomide plus high-dose dexamethasone arm versus dexamethasone plus placebo.
- With a median follow-up of 26 months, the median time to progression was 11.1 months versus 4.7 months (P < .001) and the median OS was 29.6 months versus 20.2 months (P < .001).[Level of evidence: 1iA]
- A prospective randomized study (ECOG-E4A03) of 445 untreated symptomatic patients, published in abstract form only, compared lenalidomide and high-dose dexamethasone (40 mg on days 1-4, 9-12, and 17-20, every 28 days) with lenalidomide and low-dose dexamethasone (40 mg on days 1, 8, 15, and 22, every 28 days).
- With a median follow-up of 25 months, this trial showed improved OS for patients in the low-dose dexamethasone arm (87% vs. 75% at 2 years, P = .006), despite no difference in progression-free survival (PFS).[Level of evidence: 1iiA]
- The extra deaths on the high-dose dexamethasone arm were attributed to cardiopulmonary toxicity and faster progression with subsequent therapies. DVTs were also more frequent in the high-dose arm (25% vs. 9%).
- OS favored the low-dose arm with a 2-year survival of 87% versus 75% in the high-dose arm (P = .006).[Level of evidence: 1iiA] The low-dose dexamethasone arm with lenalidomide had less than 5% DVT with aspirin alone.