High Response Rate to DLI Based Strategies for the Treatment of Refractory Disease/Relapse Following Allogeneic HSCT for Lymphoproliferative Disease.

Allogeneic HSCT is increasingly being performed for lymphoproliferative disease, particularly with reduced intensity conditioning (RIC). DLI are an important part of this strategy however there is a paucity of information in this setting although responses have been reported in Hodgkin’s disease and follicular lymphoma. We have treated 17 patients (median age 51 year; 30–62yr) with refractory disease (n=7) or disease relapse (n=10) following allogeneic HSCT for lymphoma with a DLI based strategy. The diagnosis was CLL, including 1 Richter’s (n=5); mantle cell lymphoma (n=4); high grade NHL (n=4) and follicular NHL (n=4). 15 patients received RIC transplants with either Beam/Alemtuzumab (n=11), or fludarabine/melphelan/alemtuzumab (n=4). Two patients received myeloablative conditioning with TBI and cyclophosphamide. The median time to DLI was 0.96 years (0.23 to 4.58yr) and in 15/17 the donor was a matched sibling (n=13) or 1 antigen mismatched sibling (n=2) and in 2 cases was an unrelated donor. At DLI, 6 patients had mixed chimaerism (20–95%) and 8 had full donor chimaerism with the chimaerism status being unknown in 5 cases. Patients with low grade disease received DLI either alone (n=7) or following initial radiotherapy (n=1). Patients with high-grade NHL, MCL or Richter’s transformation of CLL (n=11) all received chemtherapy pre-DLI. For the 15 sibling donors the median first dose of CD3+ cells infused was 2.0 x 10 ⁷/kg ( range 0.5–6 x 10 ⁷/kg) following which 6 achieved CR. 6 patients received a 2^nd infusion (median dose 5 x 10 ⁷/kg) with 2 achieving CR and 1 patient receiving a 3rd DLI and achieving CR. Both MUD DLI recipients achieved a CR after 2 and 3 infusions. Overall 10 out of 17 patients achieved a CR including 3/4 patients with CLL, 4/4 with MCL; 3/4 with follicular NHL but none of the 5 patients with high-grade NHL/Richter’s transformation responded. The median CD3 cell dose required to achieve CR for sibling donors was 2x 10⁷/kg whereas non-responders received a median of 5.0 x 10⁷/kg. An additional patient with CLL who developed aplasia following the first DLI had a second transplant from the same donor and is in CR at 14m giving a final overall CR rate of 70%. Response to DLI was independent of chimaerism status at relapse. Acute GvHD developed in 11 patients and was grade II in 8/10 and grade 111/IV in 3 cases. 1 patient died in CR of acute GvHD. Chronic GvHD developed in 9 of 11 surviving patients. Only 1 patient with mantle cell lymphoma has relapsed at 18m post-DLI. The median follow-up for the surviving patients is 34m (range 6m–60m). The overall survival at a median of 30 months post DLI is 58%. We conclude that lymphoma patients, particularly those with low grade NHL including mantle cell lymphoma relapsing following an allogeneic transplant have a high response rate to DLI based strategies,superior to that seen in myeloma and comparable to that seen in CML. Furthermore these responses appear durable with a low risk of relapse. Patients with high-grade disease appear to have a poor response rate despite using pre-DLI chemotherapy