UC Irvine

Background

The outcomes of patients with relapsed or refractory (R-R) acute lymphoblastic leukemia (ALL) are poor. Inotuzumab ozogamicin and blinatumomab have single-agent activity in R-R ALL. Their addition to low-intensity chemotherapy may further improve the outcomes of patients with ALL in their first relapse.

Methods

The chemotherapy was lower in intensity than conventional hyperfractionated cyclophosphamide, vincristine, adriamycin, and dexamethasone and was called mini-hyperfractionated cyclophosphamide, vincristine, and dexamethasone (or mini-HCVD). Inotuzumab was given on day 3 of each of the first 4 cycles at 1.8 to 1.3 mg/m² for cycle 1, and this was followed by 1.3 to 1.0 mg/m² for subsequent cycles. From patient 39 onward, the inotuzumab dose was reduced and fractionated into weekly doses (0.6 and 0.3 mg/m² during cycle 1 and 0.3 and 0.3 mg/m² during subsequent cycles), and blinatumomab was administered for up to 4 cycles after inotuzumab therapy.

Results

Forty-eight patients with Philadelphia chromosome-negative ALL with a median age of 39 years were treated during their first relapse. Overall, 44 patients (92%) responded, with 35 of them (73%) achieving a complete response. The overall minimal residual disease negativity rate among the responders was 93%. Twenty-four patients (50%) underwent allogeneic stem cell transplantation (ASCT). Veno-occlusive disease of any grade occurred in 5 patients (10%). With a median follow-up of 31 months, the median progression-free survival (PFS) and the median overall survival (OS) were 11 and 25 months, respectively. The 2-year PFS and OS rates were 42% and 54%, respectively. Of the 24 patients (50%) who underwent ASCT, 14 patients were alive at the last follow-up (13 [54%] in remission). Of the remaining 20 responding patients who did not undergo subsequent ASCT, 6 (30%) remained in remission at the last follow-up. According to propensity score matching, the combination of mini-HCVD and inotuzumab with or without blinatumomab conferred better outcomes than intensive salvage chemotherapy or inotuzumab alone.

Conclusions

The combination of inotuzumab and low-intensity mini-HCVD chemotherapy with or without blinatumomab shows encouraging results in patients with ALL in first salvage.