No abstract

The aim was to evaluate two transplant strategies for patients who lack HLA-identical donors, namely HLA-A, HLA-B or -DRb1 mismatched unrelated donor (MM URD) transplants (n ¼ 14) and umbilical cord blood transplants (UCB, n ¼ 27). Diagnosis, disease stage and age were similar in the two groups. Cell dose was lower in the UCB group (Po0.001). Median time to ANC of 40.5 Â 10 9 /l was 30 days in the UCB group and 17 days in the MM URD group (P ¼ 0.002). Engraftment of plt was delayed in the UCB group (P ¼ 0.03). The UCB patients required fewer erythrocyte transfusions (P ¼ 0.001). At 100 days, complete donor chimerism for CD3 was 63 and 44% in the UCB and MM URD groups, respectively. Acute GVHD of grades II-IV were 30% in the UCB group and 21% in the MM URD group. The corresponding figures for chronic GVHD were 9 and 20%, respectively. TRM was 30% in the UCB patients and 50% in the MM URD patients. Three-year survival was 66% in the UCB group and 14% in the MM URD group (P ¼ 0.006). Although the material is small and heterogeneous, engraftment was delayed, leukocyte chimerism was not significantly different and survival was superior using UCB rather than MM URD transplants.

We have developed a cancer vaccine in which autologous myeloma cells are fused with dendritic cells (DCs) resulting in the presentation of tumor antigens in the context of DC mediated costimulation. In animal models, vaccination with fusion cells results in eradication of established tumor, and in clinical trials, both immunologic and clinical responses have been observed. However, response to vaccination may be muted by inhibitory signals such as the PD1/PDL1 pathway which blunt activated T cell responses. In this study, we evaluated expression of PD1 on T cells derived from patients with multiple myeloma (MM), and PDL1 expression on primary myeloma cells and DC/MM fusions. We evaluated the effect of PD-1 blockade on T cell response to DC/MM fusion cell vaccination in vitro. Tumor cells were obtained from bone marrow aspirates of MM patients. Nonadherent peripheral blood mononuclear cells (PBMCs) obtained from patients with MM and normal volunteers were cultured in RPMI supplemented with 10U/ml IL-2, and expression of PD-1 on CD4 + T cells was assessed by flow cytometry. DCs were generated from adherent PBMCs cultured with rhIL-4, GM-CSF and TNFa and fused with MM cells by coculture in 50% solution of PEG. T cells were stimulated by DC/MM fusions in the presence or absence of PD-1 blockade. We demonstrate that PD-1 expression is markedly upregulated on T cells in patients with advanced MM. As compared to a control population in which mean levels of PD-1 expression was 6% (n 5 7), mean expression in patients with MM was 20% (n 5 9). Mean expression of PDL-1 was 66% on patient derived MM cells (n 5 3) and. 90% on DC/MM fusions (n 5 2), which potentially provides an inhibitory signal dampening fusion mediated immunologic response. We examined the effect of PD-1 blockade on T cell response to DC/MM fusions ex vivo. Enhanced fusion mediated stimulation of T cells was noted in the presence of anti-PD-1, resulting in a greater than 5 fold increase in T cell proliferation. Interferon gamma secretion by CD4 + T cells in response to stimulation by DC/MM fusions increased from 4% to 11% in the presence of PD1 blockade, while IL-10 secretion decreased from 6.5% to 3.5%. In summary, we demonstrate that PD-1 expression is increased in T cells of MM patients, and PD-1 blockade enhances activated T cell responses following stimulation with a DC/MM fusion vaccine. A clinical trial in which MM patients are treated with DC/MM fusions in conjunction with anti-PD1 is planned.

We analysed factors associated with moderate to severe acute GVHD in 111 patients treated with fludarabinbased reduced intensity conditioning (RIC) and allogeneic haematopoietic stem cell transplantation (HSCT). Most patients had a haematological malignancy. Donors were 97 HLA-A, -B and -DRb1 identical unrelated and 14 HLA-A, -B or -DRb1 allele mismatched unrelated donors. In the univariate analysis, we found ten factors associated with acute GVHD. These were diagnosis (P ¼ 0.06), GVHD prophylaxis with combinations other than CsA þ MTX (P ¼ 0.006), graft nucleated (Po0.001) and CD34 (Po0.001) cell-dose, bidirectional ABO mismatch (P ¼ 0.001), conditioning (P ¼ 0.002), hospital vs home-care (P ¼ 0.06), ATG dose (Po0.001), donor herpes virus serology (P ¼ 0.07) and an immunized female donor to male recipient (P ¼ 0.05). In the multivariate analysis, three factors remained significant: a high CD34 cell dose (Po0.001), low dose (4 mg/kg) ATG (Po0.001), and an immunized female donor to male recipient (Po0.01). Patients receiving a CD34 cell dose X17.0 Â 10 6 per kg had a higher incidence of GVHD, 53.7%, compared to 22.3% in patients receiving a lower dose (P ¼ 0.002). In patients without any of these risk factors (n ¼ 70), the incidence of acute GVHD was 14.1%, while it was 38.0 and 85.0% in patients with one (n ¼ 29) or two (n ¼ 10) risk factors (Po0.001). We concluded that risk factors for acute GVHD using RIC are similar as using myeloablative conditioning.