Donor Lymphocyte Infusions for Haematological Malignancy Relapse
Authors: Orti Guillermo , García-Cadenas Irene , Sánchez-Ortega Isabel , Jimenez Mª Jose , Alonso Laura , Azqueta Carmen , Diaz de Heredia Cristina , Ferra Cristelle , Parody Rocio , Sierra Jorge , Querol Sergio , Valcarcel David 
Published: October 2019

Abstract
Donor lymphocyte infusions (DLI) are a therapeutic approach broadly used in relapse post Allogeneic Hematopoietic Cell Transplant (Allo-HCT). In CML relapse, DLI have proven very effective, but in other hematological malignancies its effectiveness has been reported rather erratic and poor; hence the need of a better understanding of factors influencing outcomes. Questions regarding the CD3 dose, the use of G-CSF mobilized DLI or the potential toxicity associated to the use of DLI from mismatched donors remain open.
We report a cohort of 66 patients who, within a cell therapy program (Banc de Sang i Teixits, Barcelona), consecutively underwent allo-HCT and received DLI for relapse. Disease diagnosis was as follows: Lymphoproliferative malignancy (LPD) 29 patients AML and high-risk MDS 24 patients and ALL 13 patients (CML patients were not included). Median age at allo-HCT was 48 years (5-68). The combination female-donor and male-patient was 21%. 27% allo-HCT were T-cell depleted and 29% received a myeloablative conditioning regimen. Immunosupression was CsA-based in 83% of the allo-HCT. Transplants from HLA fully match donors were 54 (81%) and 19% were from mismatch donors. Indication for DLI was morphological relapse in 61 patients (92%) and disease detected by flow cytometer or at a molecular level in 5 patients (8%). 32 (48%) DLI were obtained at stem cell collection day (G-CSF mobilized) and cryopreserved, whereas 34 (52%) DLI were obtained by lymphapheresis.
The median follow-up was 198 days (9-4246). The estimated 1-year OS was 60%. A total of 100 DLI were infused, with a median of 1.5 DLI/patient and a median time from allo-HCT to DLI of 303 days (70-5153). Median CD3+ total dose was 2x107 CD3+/Kg (first DLI median dose was 1x107 CD3+/Kg). The time interval from allo-HCT to DLI ≥10 months (Log-Rank 3.64, p=0.056) was associated to better survival. In line with this, there was a trend in patients relapsing ≥ 9 months post allo-HCT (median relapse date) for better survival (Log-Rank 3.33, p=0.068). Twenty-six patients (42%) developed GvHD post-DLI. In 17 patients overall grade was 2-4, which was not associated to poorer outcome. Lately, 8 patients developed extensive chronic GvHD. The development of chronic GvHD was associated to a better survival (Log-Rank 6.07, p=0.014). A total dose ≥1x107CD3+/Kg was associated to a better survival (Log-Rank 4.78, p=0.029) compared to total lower doses. The achievement of complete remission post DLI was also associated to better OS (Log-Rank 4.54, p=0.33). Ten patients died due to non-relapse mortality causes and twenty-seven due to disease progression. Of interest, we found a trend on outcomes when using non G-CSF mobilized DLI compared to-G-GCF mobilized DLI (Log-Rank 2.65, p= 0.104). However, the administration of a pre DLI debulky therapy was not associated with better outcomes. Variables with p<0.1 were included in the multivariate analysis, which identified the achievement of CR post DLI (p=025), chronic GvHD (p=0.026), total dose ≥1x107CD3+/Kg (p=0.026) and time from allo-HCT to DLI ≥10 months (p=0.026) associated to a better OS.
Overall, this study reports a poor prognostic cohort, in which the vast majority had a post allo-HCT morphological relapse. In this group, patients treated with DLI can have a prolonged survival by achieving CR. Additionally, the survival appeared to be DLI dose-dependent, since patients receiving doses ≥1x107CD3+/Kg had better OS. Additionally, the development of chronic GvHD was associated to a better OS.
Fig 1. OS according to the total CD3 dose infused
Fig 2. OS according to the development of chronic GvHD
Fig 3. OS according to the response post DLI.

Disclosures
No relevant conflicts of interest to declare.