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Introduction: Contemporary dosing strategies for rabbit anti-thymocyte globulin (rATG) in kidney transplantation aim to reduce cumulative exposure, minimizing long-term adverse events. The use of ideal body weight-based dosing has been trialed, however concern for increased rejection post-transplant exists due to lower doses of rATG. Research Questions: The primary aim of this study was to compare rejection rates between rATG dosing protocols using actual body weight and ideal body weight and secondarily to evaluate cost savings following protocol implementation. Design: This was a retrospective study surrounding implementation of an ideal body weight-based dosing protocol for rATG. We compared 75 kidney transplant recipients in whom rATG was dosed based on actual body weight (pre-protocol group) to 64 in whom dosing was based on ideal body weight (post-protocol group), following a nine-month washout. Results: The mean cumulative rATG dose in the pre-protocol group was 6.3 mg/kg of actual body weight. When ideal body weight was used in the post-protocol group, the mean dose was 4.5 mg/kg of actual body weight. The rejection rate was 18.7% pre-protocol and 23.4% postprotocol, which did not represent a statistically significant difference (p = 0.491). The actual annual cost savings after protocol implementation exceeded $162,000, approximately $2,500 per patient. Conclusion: Results suggest ideal body weight-based dosing of rATG may reduce exposure and cost, without significantly impacting the risk of rejection in kidney transplant recipients. More studies are needed to confirm these findings.

BACKGROUND: In patients exposed to high-dose methotrexate (HDMTX; ≥1g/m(2)) with a history of elevated methotrexate (MTX) concentrations during previous doses, it is unclear whether prescribing high-dose leucovorin (HDLV) rescue limits future high levels or reduces the likelihood of acute kidney injury (AKI). METHODS: This retrospective, single-center study longitudinally followed adult lymphoma patients treated with HDMTX between 1/1/2011 and 10/31/2017 from diagnosis until 30 days after the last HDMTX dose. Endpoints included elevated MTX concentrations at 48 h (≥1.0 μmol/L) and incident AKI after each HDMTX dose. RESULTS: The 321 included patients had a median (IQR) age of 65 (57, 72) years, 190 (59%) were male, and 293 (91%) were Caucasian. There were 1558 HDMTX doses [median (IQR) 3 (2, 6) doses per patient] prescribed with 265 (83%) patients receiving more than one MTX dose. Those receiving HDLV rescue were more likely to have an elevated MTX concentration after that dose (OR = 2.69, 95% CI: 1.75–4.11, p < 0.001). Receiving HDLV rescue was associated with a greater likelihood of AKI after MTX (OR = 2.18, 95% CI: 1.38–3.43, p < 0.001). Hospital LOS was longer in those prescribed empiric HDLV rescue after MTX than those prescribed standard leucovorin with an estimated difference of 1.1 days, (95% CI: 0.5–1.7, p < 0.001). CONCLUSION: Sequential HDMTX doses are associated with a significant incidence of elevated MTX levels and AKI during lymphoma management. HDLV rescue prescribed during subsequent MTX doses in patients with a previously elevated level was not associated with improved safety outcomes. The optimal supportive care strategy following HDMTX administration requires further investigation.

Background Allogeneic hematopoietic cell transplantation (allo-HCT) allows for the possibility of cure in patients (pts) with Non-Hodgkin Lymphoma (NHL) as it provides an immunologic graft-versus-lymphoma effect. Non-relapse mortality (NRM) was prohibitive in myeloablative regimens, but technical advances with the advent of reduced-intensity conditioning (RIC) or nonmyeloablative (NMA) regimens have decreased these rates. RIC regimens are generally associated with more toxicity and higher NRM than NMA regimens. Though studies showed both approaches are safe and effective, there is lack of direct comparison between these different intensities in NHL. Methods This retrospective study identified pts aged ≥ 18 years who underwent allo-HCT for relapsed/refractory NHL between 3/2008-6/2017 at our center. Outcomes were compared between pts who received NMA and RIC conditioning, with intensity defined per CIBMTR. Progression-free survival (PFS) was the primary outcome. Secondary outcomes included overall survival (OS) and non-relapse mortality (NRM). Additional outcomes included rates of acute GVHD at Day 100, chronic GVHD, and CMV reactivation at Day 100. Regimen intensity and other variables significant by univariate analysis were included in the multivariate analysis Results For the 144 pts identified, median age was 56 years (range, 19-79). More pts received NMA regimens (n=80, 56%) and most did not undergo prior autologous HCT (n=103, 72%). NMA regimens were given more frequently to pts with indolent B-cell lymphoma and were more likely to receive ATG and/or rituximab (p = 0.008, p Conclusion Our study suggests that there are comparable and favorable outcomes between RIC and NMA regimens in allo-HCT for NHL with careful patient and regimen selection. Further studies are needed to better define criteria in choosing between NMA and RIC allo-HCT regimens for pts with NHL.

The cornea is the most frequently transplanted tissue in the human body. The primary cause of corneal graft failure is immune rejection, a highly complex sequence of innate and adaptive immune responses that interact to promote tissue destruction. As our understanding of the effector pathways that drive allograft rejection has deepened, so too has our comprehension of the diverse immunoregulatory mechanisms that restrain the effector response and promote graft tolerance. This chapter reviews the incidence, the risk factors and the cellular and molecular mechanisms that underlie corneal allograft rejection. The amalgam of anatomical features, immune cells, and immunoregulatory factors that promote tolerance and immune quiescence are described. Finally, possibilities for future therapeutic approaches to promote graft survival are considered.

Background: Prolonged methotrexate (MTX) exposure following high-dose methotrexate (HDMTX; ≥1g/m2) occurs in up to 33% of patients and potentially compromises management through increased renal and systemic toxicities.(Pinedo et al, 1977, Joerger et al, 2012) MTX-associated acute kidney injury (AKI) occurs in 5% to 30% of patients.(May et al, 2014) Rescue leucovorin dose escalation in response to an elevated 48-hour MTX concentration or serum creatinine rise is standard-of-care to reduce adverse events. The practice of preemptive leucovorin dose increases in patients with elevated MTX concentrations or previous AKI during prior MTX doses has unclear outcomes. Methods: This retrospective, single-center, cohort study was approved by the Mayo Clinic IRB and performed in accordance with the ethical standards of the 1964 Declaration of Helsinki. We identified patients newly initiated on HDMTX for management of lymphoma between 1/1/2011 and 10/31/2017 at Mayo Clinic in Rochester, MN. Patients were followed longitudinally until HDMTX was discontinued. The primary endpoint was the proportion of patients with an elevated MTX concentration (MTX > 1.0 mcmol/L) at 48 hours for the initial cycle. Secondary endpoints included the incidence of AKI (Kellum et al, 2012) and whether preemptively increased leucovorin doses during subsequent cycles of HDMTX impacted the incidence of a repeated episode of an elevated 48-hour MTX concentration, decreased incidence of AKI, or decreased hospital length of stay (LOS) compared to patients with standard leucovorin dosing (25mg intravenous every 6 hours until MTX < 0.1 mcmol/L). Results: The 321 included patients had a median (IQR) age of 65 (57, 72) years, 190 (59%) were male, and 293 (91%) were Caucasian. Baseline demographics and clinical characteristics are depicted in table 1 with those who had elevated MTX levels during their initial cycle more likely to be Male, Caucasian, have a higher BSA, have Primary DLBCL of the CNS, have bone marrow involvement, have a higher baseline SCr, higher total bilirubin, and lower albumin. The median (IQR) grams of the initial MTX dose was 6.3 (4.3, 7.5) for 84 patients (26%) receiving MTX for prophylaxis and was 12.8 grams (7.5, 16.8) for the 237 patients (74%) receiving MTX as treatment. Chemotherapy regimen distribution included 43 patients (13%) receiving HDMTX 8 grams/m2 monotherapy, 162 patients (50%) receiving HDMTX 8 grams/m2 with Rituximab and Temozolomide (MRT), and 96 patients (30%) receiving HDMTX 3.5 grams/m2 in combination with R-CHOP. Patients received a median of 3 MTX doses (IQR:2 doses, 6 doses). A total of 83 patients (36%) had an elevated MTX concentration after their first MTX dose, and the overall incidence of elevated MTX concentrations was 22% following a total of 1558 MTX doses. Preemptively increasing the leucovorin dose (based on the prior MTX concentration) was associated with a 34% rate of elevated MTX concentrations (160/466 cycles). Giving standard leucovorin (based on the prior MTX concentration) was associated with a 12% rate of elevated MTX concentration (84/713 cycles). Those with a preemptively increased leucovorin dose were more likely to have an elevated MTX concentration in that cycle (OR=2.84, 95% CI: 2.03-3.97, p Conclusion: HDMTX leads to a significant incidence of elevated serum 48hr MTX levels and AKI, 22% and 18%, respectively. Rather than protective, we found that preemptively increased leucovorin doses used during subsequent cycles did not improve the incidence of delayed elimination, reduce the incidence of AKI, or shorten hospital LOS per MTX dose. Further investigation is needed to optimize dosing strategies and supportive measures following MTX administration for management of lymphoma patients. Disclosures Barreto: FAST Biomedical, Inc: Consultancy. Leung:Takeda: Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; Aduro: Membership on an entity's Board of Directors or advisory committees; Omeros: Research Funding.