Outcomes in Allogeneic Hematopoietic Stem Cell Transplant Patients ≥ 60 Years of Age with a Novel Reduced Intensity Conditioning Regimen Incorporating Extracorporeal Photopheresis,
Authors: Cossor Furha I. , Wong Sandy , Miller Kenneth B , Black Deborah , Comenzo Raymond L. , Klein Andreas K. , Klekar Alanna , Relias Valerie , Smith Hedy , Sprague Kellie , Switkowski Karen M , Van Etten Richard A. , Klingemann Hans-Georg 
Published: October 2019

Abstract
Abstract 4153
The optimal preparative regimen for older patients undergoing hematopoietic stem cell transplantation (HSCT) is unclear. We routinely employ a reduced intensity conditioning regimen consisting of extracorporeal photopheresis (ECP) on days −6 and −5, Pentostatin 4 mg/m2/day by continuous infusion on days −4 and −3, and 600 cGy total body irradiation in 3 divided fractions on days −2 and −1 (“PPT regimen”) for patients greater than 60 years of age (Bone Marrow Transp 2004; 33:881). We now report outcomes of 38 consecutive patients ≥ 60 years old (median 62, range 60–70) (M 22, F 16) transplanted at our center between 1/1/00 and 4/1/11 for hematologic malignancies: AML (n=23), MDS (n=10), ALL (n=1), CLL (n=1), NHL (n=2) and MM (n=1). Twenty-six (68.4%) received matched related and 12 (31.6%) 6/6 matched unrelated donor (MUD) grafts. Twenty-five (65.8%) received marrow and 13 (34.2%) peripheral blood stem cell grafts. Median time to neutrophil engraftment was 16 days (3–25). Survival at day 100 was 84% (32/38), with a 13% TRM (5/38) and 3% (1/38) incidence of relapse-related death. Actuarial 1-year overall survival (OS) for all patients was 45% (95% CI 28 – 61%), and median OS in all patients was 10.6 months (95% CI 4.6 – 25.7 months). Estimated 1-year event-free survival, defined as freedom from relapse, progression, or death from any cause, was 44% (95% CI 27 – 59%). Median event-free survival for the entire cohort was 7 months (95% CI 3.6 – 25.6 months).
Grade II and grades III/IV acute GvHD (aGvHD) occurred in 8 (21%) and 2 (5%) patients respectively within 1 to 8 weeks of HSCT (median 16 days). After day 100, 6 patients had died, 1 was missing data, and 23 (74% of remaining patients and 60% of the original cohort) had symptoms of GvHD. Fourteen met NIH consensus criteria for chronic GvHD (cGvHD) including 6 with severe classic or overlap cGvHD while 6 had recurrent, 2 persistent and 1 delayed aGvHD. Of those with aGvHD after day 100, 2 patients exhibited ≥ grade III disease. Median time to onset of cGvHD was 4.1 months (3.3 – 11.7). Among patients who received marrow as their stem cell source (n=25), incidence of grades II-IV aGvHD was 32% (24% grade II, 8% grade III/IV), and incidence of any GvHD from day 100 up to date of death or last follow-up was 68%. Among those who received blood stem cells (n=13) incidence of grades II-IV aGvHD was 15% (all grade II) and incidence of GvHD from day 100 until date of death or last follow-up was 83%. There was no statistically significant difference between those who received marrow versus blood stem cells with respect to incidence of either grade II-IV aGvHD or GvHD after day 100 (P =0.27 and 0.36). For those who received MUD transplants (n=12), incidence of grades II-IV aGvHD and of any post-day 100 GvHD were 42% (33% grade II, 8% grade IV) and 75% respectively, and in those who received related donor transplants (n=26) were 19% (15% grade II, 4% grade IV) and 74%, respectively. There was no statistically significant difference between MUD HSCT versus related donor HSCT patients with regard to grade II-IV aGvHD or GvHD after day 100 (P =0.14 and 0.94). In conclusion, our approach was well tolerated by HSCT patients > 60 years old, provided prompt myeloid recovery and had an acceptable incidence of post-day 100 severe chronic (19%) or > grade II late acute GvHD (6%).

Disclosures:
Off Label Use: Pentostatin and Extracorporeal photopheresis are not FDA approved for conditioning prior to allogeneic transplant. Comenzo:Elan: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Millenium: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Neotope: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.