Treatment Regimens

All patients received bortezomib-based regimens as induction therapy, including PD (bortezomib and dexamethasone), PCD (bortezomib, cyclophosphamide, and dexamethasone), PAD (bortezomib, doxorubicin, and dexamethasone), PTD (bortezomib, thalidomide, and dexamethasone), and VRD (bortezomib, lenalidomide, and dexamethasone). All patients received subcutaneous bortezomib 1.3 mg/m²; young patients (< 65 years old) received a 28-day course of treatment on days 1, 4, 8, and 11. Older patients (≥ 65 years old) received a 35-day course of treatment on days 1, 8, 15, and 22. Dexamethasone 20 mg/day was administered intravenously following bortezomib on days 1–2, 4–5, 8–9, and 11–12 (or days 1–2, 8–9, 15–16, and 22–23). Similarly, doxorubicin (10 mg/m²) and cyclophosphamide (200 mg/m²) were given intravenously on days 1, 4, 8, and 11 (or days 1, 8, 15, and 22). Thalidomide (100 mg/day) and lenalidomide (10–25 mg/day) were taken orally during the entire treatment cycle.

After three to four cycles of induction therapy, ASCT was implemented in a number of patients eligible for transplantation, according to their age, general state, and willingness. Other patients not eligible for transplantation continued to receive two to four courses of consolidation therapy, which was basically the same as the induction regimens.

After three to four cycles of induction and consolidation therapy with or without ASCT, the majority of patients received maintenance therapy. A large proportion of patients received PIs -based regimens such as PD, PCD, PAD, PTD, VRD for maintenance. During maintenance, all patients received bortezomib-based regimens with a 3-month cycle on days 1, 8, 15, and 22, the doses were basically as same as the induction therapy unless individual patients are intolerant because of severe adverse reactions. The other group of patients received immunomodulators as maintenance therapy, such as T (thalidomide), R (lenalidomide), TD (thalidomide and dexamethasone), and RD (lenalidomide and dexamethasone), thalidomide was taken everyday, and lenalidomide was taken on days 1 to 21 of 28-day cycles.