Haploidentical Peripheral Blood Stem Cell Transplantation (Haplo-PBSCT) with Cyclophosphamide Pos Transplant (CyPost) in High-Risk Hematologic Malignancies. Results of 5 Years in Transplant Center in Northeast of Mexico

Introduction: Haploidentical peripheral blood stem cell transplantation ( Haplo-PBSCT) is a curative option in patient with hematology malignancy. In Mexico is very difficult to find an identical HLA donor , for this reason Haplo PBSCT it is an option in our public Health institution. Materials and methods: we aimed a retrospective study since (2017 -2021) in our Hospital Unidad Médica de alta Especialidad 25, Instituto Mexicano del Seguro Social (IMSS UMAE 25) Monterrey, Mexico. We include patients over 15 years of age who were undergo Haplo PBSCT with hematolgy malignancies . We performed Analysis of Overall and Relapse-free survival with kaplan meier curves and incidence of acute and chronic graft versus host disease (GVHD) and percentage of Transplant-Related Mortality (TRM). Results: we analized a 38 patients, the median age was 35 years (range 15-64). Of the total , 25 were male (65%) and 13 famale (34%). The rest of baseline data is described in table 1. The median time of neutrophil engrafment was days 17 ( 11-26 ) and platelets was 19.5 days ( 12-38 ). The Incidence of Primary Graft failure was 18 % ( seven patients). Patients with graft had 99-100% chimerism at day 100. The Incidence of aGVHD was 26 % and the cGVHD was 16%. DLI was used in four patients to treat passenger lymphocyte syndrome (2 patients) and ( 2 patients) with severe graft rejection. The principal cause of death was sepsis in eleven patients (29%). Two patients with acute leukemia (AML and ALL) died after development of post transplant lymphoproliferative disease. The TRM was 28.2%. There were no relapse-related deaths during follow-up after Haplo-PBSCT. The median of survival was 4.5 months ( range 1-44) with Overall Survival (OS) of 42 % at 3 years ( figure 1). Conclusion: Our analysis shows results that were comparable with those published in first world international transplant centers . Relapse remains the major cause of transplant failure, in our population the antigenic disparity between donor and recipient can strengthen the immune response versus disease. Haplo-PBSCT is a feasible transplantation method in patients with hematological malignancies in developing countries with limited resources. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Two Cases of Tacrolimus-related Transplant-associated Thrombotic Microangiopathy Retinopathy after Allogenic Peripheral Blood Stem Cell Transplantation

Purpose: We report two cases of tacrolimus-related transplant-associated thrombotic microangiopathy (TA-TMA) retinopathy in leukemia patients who had undergone allogenic peripheral blood stem cell transplantation (PBSCT).Case summary: (Case 1) A 58-year-old woman with a history of PBSCT due to acute myelocytic leukemia and taking tacrolimus was referred to the ophthalmology clinic with visual disturbance. Her visual acuity (VA) was 0.4 in the right eye and 0.5 in the left eye. Multiple cotton wool spots and retinal hemorrhages were found in both eyes on fundus examination. Multiple capillary non-perfusions were seen on fluorescein angiography (FA). Tacrolimus-related TA-TMA retinopathy was suspected. Tacrolimus was discontinued and plasmapheresis was performed. After 3 months, neovascular glaucoma developed and her VA became “counting fingers” at 20 cm in both eyes. (Case 2) A 20-year-old man with a history of PBSCT due to acute lymphocytic leukemia and taking tacrolimus was referred to our clinic because of decreased VA in both eyes. His VA was 0.05 in the right eye and 0.025 in the left eye. Fundus and FA findings were the same as in Case 1, and the patient was suspected to have tacrolimus-related TA-TMA retinopathy. Tacrolimus was discontinued and plasmapheresis was performed. His VA was 0.2 in the right eye and 0.4 in the left eye at 1 month after treatment.Conclusions: It is necessary to consider TA-TMA retinopathy in leukemia patients taking calcineurin inhibitors, such as tacrolimus, who have decreased VA. Early diagnosis and treatment are important.

Prophylactic Peripheral Blood Stem Cell Collection in Patients with Extensive Bone-Marrow Infiltration of Neuroendocrine Tumours Prior to Peptide Receptor Radionuclide Therapy with 177Lu-DOTATATE

Peptide receptor radionuclide therapy (PRRT) of metastatic neuroendocrine tumors (NET) can be successfully repeated but may eventually be dose-limited. Since 177Lu-DOTATATE dose limitation may come from hematological rather than renal function, hematological peripheral blood stem cell backup might be desirable. Here, we report our initial experience of peripheral blood stem-cell collection (PBSC) in patients with treatment-related cytopenia and therefore high risk of bone-marrow failure. Five patients with diffuse bone-marrow infiltration of NET and relevant myelosuppression (≥grade 2) received PBSC before one PRRT cycle with 177Lu-DOTATATE (7.6 ± 0.8 GBq/cycle). Standard stem-cell mobilization with Granulocyte-colony stimulating factor (G-CSF) was applied, and successful PBSC was defined as a collection of >2 × 106/kg CD34+ cells. In case of initial failure, Plerixafor was administered in addition to G-CSF prior to apheresis. PBSC was successfully performed in all patients with no adverse events. Median cumulative activity was 44.8 GBq (range, 21.3–62.4). Three patients had been previously treated with PRRT, two of which needed the addition of Plerixafor for stem-cell mobilization. Only one of five patients required autologous peripheral blood stem-cell transplantation during the median follow up time of 28 months. PBSC collection seems to be feasible in NET with bone-marrow involvement and might be worth considering as a backup strategy prior to PRRT, in order to overcome dose-limiting bone-marrow toxicity.