First-Line Treatment of Multiple Myeloma with a Combination of Thalidomide, Dexamethasone, and Zoledronate (TDZ) in an Inner-City Population with High HIV Prevalence.

Background: The combination of thalidomide and dexamethasone is a rescue regimen for multiple myeloma (MM) in relapse, and for pretransplant in newly diagnosed patients. The bisphosphonate zoledronate mitigates bone resorption and possibly tumor growth and angiogenesis. The long-term utility of this combination in a newly diagnosed inner-city MM population with high prevalence of HIV-infection is addressed in this phase II trial. MM is reported with increased frequency in patients with HIV infection, and optimal treatment of MM in these patients is unknown.

Methods: Of 30 consecutive enrollees, 22 (16F/6M) were evaluable. Mean age was 61 years (range = 43–82); all had skeletal lesions, and 27% (n = 6) were HIV+ (mean age = 47, range 46–50, all female). Patients received thalidomide 100 mg QD, dexamethasone 10–40 mg PO on Days 1–4, 9–12, and 17–20 monthly for six months, then on Days 1–4 monthly; and zoledronate 4 mg IV monthly, until progression or relapse. Baseline β₂-microglobulin indicated high risk for all patients (mean = 6.2 μg/ml, SD = 3.8). At enrollment, 4 patients had AIDS, and 3 were on HAART.

Results: Overall response rate (> 50% decrease in M protein) was 72% (n = 13), and 83% (n = 5) in HIV+ patients. In 27% (n = 6), M protein levels were < 0.3 g/dL, including 3 HIV+ patients on HAART. In 23% (n = 5), M protein was reduced by < 50%. Median time to response was 2 months, and mean time on TDZ was 11 months. TDZ treatment decreased serum β₂-microglobulin (P <.001). Two patients relapsed, and one patient with HIV and concomitant plasmacytoma did not respond. All three eventually died. Response to treatment was unaffected by HIV status or antiretroviral treatment. Side effects of TDZ were reversible by anticoagulant therapy or dexamethasone reduction.

Conclusions: TDZ had significant activity against newly diagnosed MM, suggesting that zoledronate may facilitate response with lower doses of thalidomide. HIV status did not affect response, indicating that this regimen is compatible with concomitant antiretroviral treatment and is equally effective in HIV+ patients. These findings underscore the potential effectiveness of this combination of anti-myeloma agents as a long-term alternative, particularly in patients for whom transplant therapy is not feasible.