ALBERT

Description: INTRODUCTION: In patients with so called "late suboptimal responses" (patient with complete cytogenetic response (CCyR) without major molecular response (MMR) after 18 months of imatinib) , the role of dasatinib has not been evaluated. Dasatinib has unique immunomodulatory effects especially on the proliferation and activation of T- and NK-cells. Yet, how dasatinib affects the migration of lymphocytes is unknown. DASAPOST is the first clinical trial evaluating efficacy and safety of dasatinib in patients with late suboptimal response (now considered as ELN2013 as warning). Another aim is to correlate new immunological aspects related to dasatinib and its possible correlation with responses. METHODS: We are presenting results of first 18 patients enrolled in the phase II DASAPOST study (NCT01802450). Main inclusion criteria were patients treated with late suboptimal response by ELN09 (CCyR without MMR after 18 months of treatment. Sokal risk groups were (L/I/H) 22.5%, 50% and 22.5%. All BCR-ABL/ABL (IS) measurements were centralized in an EUTOS laboratory. An exhaustive lymphocyte migration study was done, including immunophenotipying pre and post samples (CD 45, CD3,CD8, CD16, CXCR3, CXCR4, CD56 and CCR7), migration assay (chemokines CXCL10, CCL19+CCL21 and CXCL12) and CXCL10 plasma concentration measured by ELISA. RESULTS: - Clinical: Median follow up was 288 days (100-380). Three out of 18 (16%) patients had discontinued dasatinib due to side effects (pancreatitis, pleural effusion and low grade, persistant side effects (fever, arthralgias, anemia and astenia). All patients have been evaluated at 3 months, 17 at 6 months and 11 at 12 months. Cumulative incidences by ITT of MMR by 3 and 6 months were 50% and 81%. Cumulative incidences by ITT of MR4.5 by 3 and 6 months were 18% and 25%, respectively. - Inmunological: Dasatinib intake induced a significant increase of NK-cells and decrease of percentage of T-cells. Further, it increased CD8+ T cells, while reducing the proportion of CD4+ T-cells among the total T-cells. With the first dose of dasatinib (to),the percentage of CCR7 was lower in CD4+ and CD8+ T-cells in the post-samples. Lymphocyte migration was studied with transwell assays. At t0, post-samples showed a reduced migratory capacity towards the chemokines CCL19 and CCL21 in both CD4+ and CD8+ T-cell subsets. Patients were classified as mobilizers (n=14) or non-mobilizers (n=3) depending on whether they experienced an increase in the absolute lymphocyte counts after the first intake of dasatinib or not, showing different lymphocyte distribution and migratory capacity. In order to study the long term effects of dasatinib, we calculated the fold change (FC) of absolute lymphocyte counts pre- and post-dasatinib intake. Patients were divided into two groups based on whether in the 3 months samples (t3) had a higher ("increase group") or a lower ("decrease group") FC compared with t0. The migratory capacity of these two groups was studied in basal conditions and towards CCL19+CCL21 or CXCL10. We found no differences in basal migration in the "increase "group, while, the basal migration in the "decrease" group was quite promoted at t0 and t3. Further, migration towards CCL19+21 in post-samples is even more inhibited in "increase" patients at t3, whereas in the "decrease" patients the inhibition is diminished. The patients were divided into two groups based on the achievement of MMR at t3. At t0 both patient groups had similar migratory capacity, however, at t3, responders maintained significantly impaired migratory capacity to CCL19+21, compared with non-responders. CONCLUSIONS: Our study shows, for the first time to our knowledge, that in patients treated with Imatinib and with late warning responses, switch to Dasatinib induced MMR in 83% of the patients, although 16% discontinued treatment because of toxicity. We reported for the first time that dasatinib has significant effects on lymphocyte migration, and these are associated with early response. Disclosures García-Gutierrez: Ariad: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Casado:Pfizer: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Roche: Honoraria, Research Funding. Sánchez-Guijo:Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Ariad: Consultancy, Speakers Bureau. Boque:Celgene: Honoraria; BMS: Honoraria; Novartis: Honoraria. Muñoz-Calleja:BMS: Research Funding. Steegmann:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pfizer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Ariad: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Description: Background. Cytomegalovirus (CMV) is a widespread persistent β–herpesvirus, which can cause severe complications during primary infection or reactivation in immunocompromised patients, such as after allogeneic stem cell transplantation (alloSCT). Another major complication associated with alloSCT is graft-versus-host disease (GVHD). The pathogenesis of GVHD involves migration of the transplanted donor naïve T-cells into the secondary lymphoid organs in the recipient, which is mainly steered by CD62L and CCR7. As these homing molecules have been associated with both acute GVHD (aGVHD) and chronic GVHD (cGVHD), we studied whether the CMV serostatus of the donor affects the lymphoid composition of the graft product and whether this phenotype can predict CMV reactivation and GVHD. Methods. This single-center study included 77 donor-recipient pairs who underwent alloSCT. 64 pairs were HLA identical, 12 had 1 mismatch and 3 had 2 mismatch. 36 donors were related to their recipients. All recipients were followed at least for 100 (aGVHD) or 360 days (cGVHD) after transplantation. 43 donors were CMV-seropositive (CMVpos) and 34 were CMV-seronegative (CMVneg). 62 recipients were CMVpos, and 32 of them developed CMV reactivation, 25 aGVHD and 30 cGVHD. Samples from the graft product (donor) were phenotyped by flow cytometry (CD45, CD3, CD8, CD4, CD62L, CCR7) and both frequency (freq) and absolute number (abs) of each T-cell subpopulation were analyzed. Results. When the donors were divided based on their CMV serostatus, we observed that the grafts from CMVpos donors had a lower freq of naïve (CCR7+CD62L+) CD4+ T-cells (of lymphocytes p=0.06, of CD3 p=0.06, of CD4 p=0.07) and naïve CD8+ T-cells (of leukocytes p=0.03, of lymphocytes p=0.041, of CD3 p=0.011, of CD8 p=0.012) compared to CMVneg donors. Further, the abs of transplanted naïve CD8+ T-cells was significantly lower in the grafts from CMVpos donors (p=0.048). No differences were observed in T-cells (CD3+, CD4+, CD8+). We next studied if the CMV-serostatus and T-cell phenotype of the graft associates with GVHD. CMVpos donors whose recipients developed aGVHD had higher abs (p=0.05) and freq of naïve CD8+ T-cells (of lymphocytes p=0.08, of CD3 p=0.08, of CD8 p=0.11) compared to those without aGVHD. The same trend was observed with abs (p=0.11) and freq of CCR7+CD4+ T-cells (of leukocytes p=0.15). Similarly, those CMVpos donors whose recipients developed cGVHD had higher abs (p=0.05) and freq of CCR7+CD8+ T-cells (of leukocytes p=0.03, of lymphocytes p=0.06). Further, cGVHD patients who received the transplant from CMVpos donors were infused with a higher freq of CD3+ (of leukocytes p=0.03) and CD4+ T cells (of leukocytes p=0.04) than patients who received a graft from CMVpos donors but did not develop cGVHD. In contrast, CMVneg donors who developed aGVHD had a higher freq of CD3+ (p=0.018) and CD4+ T-cells (p=0.09), whereas no differences were seen in the T-cell subpopulations. Conversely, the abs (p=0.08) and freq of CCR7+CD4+ T-cells (of leukocytes p=0.11) were higher in those who later developed cGVHD. To study whether the graft lymphoid composition can be used to predict CMV reactivation, we analyzed the lymphoid composition in the graft product of those donors (both CMVpos and CMVneg) whose recipients were CMV seropositive but did not develop any form of GVHD (to avoid the influence of GVHD in the reactivation of CMV). Despite the low number of patients (CMV reactivation n=9, and no CMV reactivation n=13), we observed trends of higher portion of CD4+ T-cells (p=0.09 of lymphocytes, of CD3 p=0.20) and CCR7+CD4+ T-cells (of lymphocytes p=0.18, of CD4 p=0.16) in those grafts that were transplanted into CMV seropositive recipients who did not reactivate CMV. Conclusions. CMVpos donors whose recipient developed either aGVHD or cGVHD had a higher abs and freq of naïve CD8+ T-cells, which was not seen with CMVneg donors. This suggests that seropositivity sets the abs and freq of CD8 subpopulations near to a decisive cutoff for the development of GVHD. Conversely, other factors influences the development of GVHD in those patients whose donors were seronegative. In other words, seropositivity of the donor affects the graft composition and thus the risk of GVHD. Finally, our data indicate that a higher proportion of naïve or central memory CCR7+ CD4+ T cells in the donor graft could prevent CMV reactivation suggesting that graft composition affects also CMV reactivation. Disclosures No relevant conflicts of interest to declare.