Comparison of Post-Transplant Outcomes in Non-Hodgkin Lymphoma (NHL) Patients Mobilized with or without Plerixafor Added to Chemomobilization

Plerixafor, a CXCR4 antagonist, is used in a combination with G-CSF with or without chemotherapy to enhance mobilization of hematopoietic stem cells (CD34⁺) from the bone marrow to circulation. Prior studies have shown that plerixafor may mobilize more primitive stem cells and also have impact on other cell populations too. These changes may have impact in engraftment, immunological reconstitution and post-transplant outcome. However, only limited data are available in regard to effects of plerixafor in post-transplant outcomes.

Eighty-nine patients with non-Hodgkin lymphoma (NHL) were included in this study. The patients received disease-specific chemomobilization (most commonly cytarabine based) with G-CSF. In addition, 33 patients (37 %) received plerixafor because of insufficient mobilization, poor collection yields or late mobilization (plerixafor group). Fifty-six patients served as controls (control group). The median age was 58 years in the plerixafor group and 57 years in the control group (p=0.515). The most common histology was diffuse large B-cell lymphoma in both groups. The proportion of patients beyond CR1 or PR1 was significantly higher (55 % vs. 32%, p=0.046) in the plerixafor group. All patients were treated with a single dose (6 mg) of pegfilgrastim after stem cell infusion. Patients were followed after high-dose chemotherapy in regard to haematopoietic engraftment and outcome.

The median amount of collected CD34⁺ cells was 3.5 × 10⁶ CD34⁺ cells/kg (range 1.3 – 8.9 × 10⁶ CD34⁺ cells/kg) in the plerixafor group and 4.2 × 10⁶ CD34⁺ cells/kg (range 1.9 – 18.6 × 10⁶ CD34⁺ cells/kg) in the control group (p=0.076). The median number of aphaeresis was two (range 1–5) in both groups (p=0.17). The median neutrophil engraftment was 10 days in both groups (range 8–81 days in the plerixafor group and 8–21 days in the control group). The median time to platelet engraftment was 14 days in both groups (range 10–165 days in the plerixafor group and 10–91 days in the control group). The incidence of neutropenic fever was comparable between the groups (71% vs. 76%, p=0.906). The median follow-up time from ASCT was 373 days (range 5–929 days) in the plerixafor group and 518 days (range 81–1175 days) in the control group (p=0.052). No difference in counts of haemoglobin, leucocytes, lymphocytes or platelets were observed at +1, +3, +6, +12 months except for haemoglobin which was significantly higher in the plerixafor group at +3 months. Progression-free survival (PFS) was 72 % in the plerixafor group and 75 % in the control group (p=0.69). Overall survival (OS) was also comparable between the groups (82 % vs. 84 %, p=0.67).

The recovery from ASCT and outcome after ASCT seems to be comparable in lymphoma patients whether plerixafor is used or not. Prospective studies including more detailed characterisation of graft cellular content in regard to CD34⁺ cell subtypes, T-cell repertoire and NK-cells are needed to assess the impact of mobilization method post-transplant outcome.

Jantunen:Genzyme: Has participated in EU Leadership meeting organized by Genzyme as well as Medical Advisory Board meeting organized by Genzyme Other, Honoraria.