Historical Analysis of a Cohort of Chilean Patients Treated with Autologous Stem Cell Transplantation Since 1993: Optimization of Stem Cell Collections, Risk Factors for Poor Mobilizers and Efficient Plerixafor Use
Authors: Maldonado Mauricio Sarmiento , Veronica Jara , Arellano Silvana , Katherine Soto , Lorca Carla , Pizarro Isabel , Bertin Pablo , Galleguillos Mauricio , Rivera Elizabeth , Rodriguez Isabel , Beffermann Nicole , Ocqueteau Mauricio , Pereira Jaime 
Published: November 2019

Introduction
Autologous hematopoietic transplantation (autoHT) is an effective treatment in myeloma and lymphoma patients. To perform it, an adequate harvest of stem cells is required. Collection of stem cells can be challenging in some patients, because they do not achieve satisfactory CD34 cell counts with GCSF + - chemotherapy. Plerixafor is a potent drug that promotes the release of stem cells from medullar niche to peripheral blood and allows satisfactory harvests but at a high cost. Different criteria of use have been applied in several countries to select patients eligible for treatment with plerixafor, with a high variability of prescription modalities. Even more, there are difficulties in precise the optimal schedule and dosification mainly by differences in the number defined as optimal collection, because some centers use the minimum tolerated collection cellularity of 2.0 x106 CD34/ kg and others use more stringent cells recounts. Development of our own algorithm for stem cell harvest is mandatory.
Methodology
We performed a retrospective analysis of the harvests performed in patients treated with autoHT in our institution since 1993. In 2013 plerixafor was available in our country and was included in our transplantation program. Satisfactory harvest was defined with total cellularity obtained of 2.5 x106 CD34/ kg.
Results
During the last 26 years, 273 patients with myeloma and lymphoma were treated with autoHT. Before 2013, all patients (n=112) were mobilized with GCSF +- chemotherapy. In this period, 75% of patients had successful harvests, requiring more than 2 apheresis procedures in 30% of them. Median cellularity obtained was 2.7 x106 CD34/ kg (range 1.2-15). Since 2013, 161 patients were treated with autoHT and we found that 80% of patients obtained satisfactory harvests with 1 apheresis and satisfactory harvests were obtained in 97% using plerixafor in 50% of them (p < 0.001). Median cellularity obtained was 4.8 x106 CD34/ kg (range 2-14) (p < 0.001). In multivariate analysis, after 2013 the only factor that predicted the need for plerixafor was the presence of less than 30,000 CD34 / ul at the day of the apheresis (OR 0,3 p <0.001). Other variables such as previous pelvic irradiation, use of IMID's, gender and advanced aged were no associated with harvest failure.
Conclusions
Historically, we have observed an improvement of the quality of cellularity for autoTH. Since the avaibility of plerixafor, more patients could be transplanted, better cellularity was obtained and less apheresis procedures were required. The rational and standardized use of plerixafor favors satisfactory harvests in patients of our country who require autologous transplantation. Using a simplified algorithm using exclusively the CD34 counts before apheresis allows us satisfactory harvests and efficient use of plerixafor, establishing the appropriate harvest and apheresis schema for our population allowing optimization of transplantation costs.
Keywords: autologous hematopoietic stem cell transplantation, plerixafor, multiple myeloma, lymphoma, GCSF.

Disclosures
No relevant conflicts of interest to declare.