Low Efficacy of Thalidomide in Improving Response after Induction in Myeloma Patients Candidate to High-Dose Therapy.

Background: In multiple myeloma (MM) patients (pts) undergone high dose therapy, the outcome of the transplant is better if a good response is achieved before the procedure. Therefore, different attempts have been made in intensifying pre-transplant chemotherapy to improve the response. Aim of the study was to evaluate the safety and efficacy of Thal-Dex in improving the response rate after initial VAD therapy.

Methods: 61 untreated MM pts aged ≤65 years were addressed to high dose program with a debulking therapy with 3 pulse-VAD cycles followed by Thal-Dex for 3 months at the following schedule: Thal 100 mg/d orally at bed time, continuously for 3 months, Dex 20 mg/d orally on days 1–4 and 14–17 every 28 days. Response at the end of each phase was defined as follows: complete remission (CR), disappearance of serum and urine monoclonal component (MC) by immunofixation and bone marrow plasmocytosis (BMPC) <5%; very good partial remission (VGPR)/partial remission (PR)/minimal response (MR)/stable disease (SD), reduction of at least 90%/50%/25%/<25% of serum and urine MC, and of BMPC; progression, increase of serum and urine MC or BMPC. Toxicity was registered according to WHO classification.

Results: Responses after VAD were evaluable in 60 pts: RC 7%, VGPR 38%, PR 27%, MR 10%, SD 10%, progression 8%. Four pts dropped out after pulse-VAD for progression and in 1 for toxicity. Responses after Thal-Dex in 52 evaluable pts were: RC 12%, VGPR 40%, PR 17%, MR 4%, SD 4%, Progression 23%. Three pts dropped-out during Thal-Dex, 1 for progression and 2 for toxicity. Of note, pts who obtained a scarce response to VAD, namely a MR or SD, showed a higher probability (85% of cases) to have a progression during or after the administration of Thal-Dex. Statistical analysis (Kendall Concordance Coefficient (p<0.0001); and non parametric Wilcoxon matched pairs test (p=0.12)) did not show any improvement of the response rate after Thal-Dex with respect to the evaluation after pulse-VAD cycles.The pulse-VAD related toxicity was as follows: 1 died for sepsis after the first pulse-VAD, 5 developed grade 2 WHO infections, 4 developed mild constipation. Side effects during Thal-Dex therapy were: grade 1–2 peripheral neuropathy in 7 pts, grade 1 constipation in 6 pts; 4 pts developed thrombotic events (TVP in 3, and a bowel infarction with subsequent colectomy in one).

Conclusions: The combination thalidomide-dexamethasone after pulse-VAD is not effective in improving response rate, and shows an additional toxicity. Thus it does not seem useful for the intensification before transplant.