Low-dose dexamethasone and thalidomide with higher frequency zoledronic acid (dtZ) for newly diagnosed multiple myeloma

Abstract

18506 Background: Although dexamethasone (Dex), thalidomide (Thal) and zoledronic acid (Zol) have frequently been combined for the treatment of multiple myeloma (MM), the ideal dosing schedule is unknown. We previously reported that lower doses of Dex and Thal can be effectively combined with high-frequency dosing of Zol (Haematologica 2005). Methods: This “dtZ” regimen - which comprises weekly Dex 20 mg OM for 4 days, Thal 50 mg ON, and 3-weekly Zol 4 mg - resulted in an impressive response rate (RR) of 61.6% and near complete remission (nCR)/complete remission (CR) rate of 7.7% in 26 patients with relapsed/refractory MM. Results: In this present study, we treated 22 newly diagnosed MM patients with “dtZ” and report an even more impressive RR of 100.0% and nCR/CR rate of 20–35%. The median time to response was 1.8 months and median time to maximum response was 2.2 months. The median time to progression (TTP) has not been achieved yet. As expected, low-dose Dex/Thal resulted in lower (18.1%) grade 3 or 4 toxicities. These were all infections; which lead to further dose-reduction of Dex. There were no thromboembolic events, despite the fact that aspirin was not routinely given. Of particular interest, 3- weekly Zol was not associated with any significant decrease in renal function, and none of our patients developed osteonecrosis of the jaw (ONJ). In fact, at the time of writing of this abstract, more than 1,000 doses of Zol had been administered in a 3-weekly fashion to these as well as other patients, and only 1 patient developed ONJ. This patient who had already received greater than 20 doses of Zol healed uneventfully after receiving appropriate outpatient dental treatment, and subsequently received another 8 doses of Zol with no recurrence of ONJ. Conclusion: In conclusion, the Zol-based “dtZ” regimen is potentially a highly-effective and safe frontline regimen for MM. Using Zol every 3 weeks with lower doses of Dex and Thal does not appear to increase the rate or severity of nephrotoxicity or ONJ. Although we do not know exactly why every patient responded to “dtZ”, we speculate that this could be due to a critical balance that has been achieved between the anti-MM, anti-osteoclastic and immunostimulatory effects of the individual drugs of the combination. No significant financial relationships to disclose.