Between January 2001 and June 2008, 315 adult patients (median age 43 years, range 16-65) including 203 males and 112 females undergoing hematopoietic stem cell transplantation (HSCT) had serial monitoring for cytomegalovirus (CMV) followed by initiation of preemptive therapy. The majority (62.1%) had a conventional myeloablative transplant with 116 (36.9%) having a reduced-intensity conditioning (RIC) transplant, using either matched sibling/family (63.3%) or unrelated donors (36.7%). Graft source was peripheral blood stem cells in 257 (81.5%), bone marrow in 41 (13.1%), and cord blood in 16 (5.4%). T-cell depletion with anti-thymocyte globulin or alemtuzumab was used in 35%. Based upon CMV serostatus, patients were classified into low risk (donor [D]-/recipient [R]-), intermediate risk (D+/R-), or high risk (D-/R+ or D+/R+). Serial weekly monitoring for CMV viremia was performed using a qualitative polymerase chain reaction (PCR) and when positive, quantification was done using either pp65 antigen or a quantitative PCR. CMV reactivation was seen in 123 patients (39.1%) at a median of 50 days post HSCT (range 22-1978). CMV serostatus was the most important risk factor with incidence of 53% in the high-risk group (53.3%) compared with 10.2% in the intermediate risk and 0% in the low-risk group (P<0.0001). Other significant risk factors identified included use of alemtuzumab during conditioning (P=0.03), RIC transplants (P=0.06), and the presence of acute graft-versus-host disease (GVHD) (P<0.0001). On a multivariate analysis, CMV serostatus, RIC transplants, and acute GVHD remained independent predictors of CMV reactivation. All were treated with antiviral therapy with responses seen in 109 (88.6%). Sixteen patients (13%) developed CMV disease at a median of 59 days post HSCT (range 26 days-46 months), 8 of whom died. At a median follow up of 43 months (range 6-93), 166 patients (52.6%) are alive with a significantly higher survival among patients without CMV reactivation (57.2%) as compared with patients with CMV reactivation (45.5%; P=0.049). CMV reactivation and disease remains a major problem in high-risk patients undergoing allogeneic HSCT. Novel prophylactic measures such as immunotherapy and drug prophylaxis need to be considered in this specific group of patients.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • The pharmacokinetics of oral busulphan given four times daily has been extensively studied. • Large inter‐ and intravariability in oral busulphan exposure has led to attempts at pharmacokinetic monitoring. • However, there have been limitations in the pharmacokinetic analysis due to inadequate characterization of the elimination phase in a 6‐h dosing interval, due to late absorption in some patients. • Intravenous (i.v.) busulphan is a relatively new administration method and there have been relatively few studies on the pharmacokinetics of i.v. busulphan, especially when given as a single daily dose. WHAT THIS STUDY ADDS • Inter‐ and intrapatient variability in i.v. busulphan pharmacokinetics is comparable to that previously observed with oral busulphan, suggesting that pharmacokinetic monitoring is advisable. • Children with immune deficiencies, in particular, have widely variable exposure. AIM To examine inter‐ and intrapatient variability in the pharmacokinetics of intravenous (i.v.) busulphan given as a single daily dose to children with malignant (n = 19) and nonmalignant (n = 21) disease. METHODS Busulphan (120 mg m−2, 130 mg m−2 or 3.2 mg kg−1) was administered over median 2.1 h. Blood samples (4–10) were collected after the first dose, busulphan concentrations were measured and pharmacokinetic parameters, including clearance (CL) and area under the concentration–time curve (AUC), were determined using the Kinetica software (Innaphase). Interpatient variability was assessed as percent coefficient of variation (% CV). Intrapatient variability was assessed by calculating percent differences between observed full dose AUC and AUC predicted from an initial 65 mg m−2 dose in 13 children who had busulphan pharmacokinetic monitoring. RESULTS Clearance of i.v. busulphan in 40 children was 4.78 ± 2.93 l h−1 (% CV 61%), 0.23 ± 0.08 l h−1 kg−1 (% CV 35%) and 5.79 ± 1.59 l h−1 m−2 (% CV 27%). Age correlated significantly (p < 0.001) with CL (l h−1) and CL (l h−1 kg−1), but not with CL (l h−1 m−2). AUC normalized to the 130 mg m−2 dose ranged from 14.1 to 56.3 mg l−1.h (% CV 37%) and also did not correlate with age. Interpatient variability in CL (l h−1 m−2) was highest in six children with immune deficiencies (60%) and lowest in seven children with solid tumours (14%). Intrapatient variability was <13% for nine (of 13) children, but between 20 and 44% for four children. CONCLUSIONS There is considerable inter‐ and intrapatient variability in i.v. busulphan CL (l h−1 m−2) and exposure that is unrelated to age, especially in children with immune deficiencies. These results suggest that monitoring of i.v. busulphan pharmacokinetics is required.

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Introduction R-mini-CHOP is an established standard of care in elderly patients with DLBCL, with a 2yr OS of 59% and PFS of 47% (Peyrade et al, Lancet Oncol 2011). The addition of ibrutinib to full dose R-CHOP in younger pts with DLBCL has efficacy, but significant toxicity limits the ability to complete therapy in pts ≥60 yrs (Younes et al, JCO 2019). We previously demonstrated the deliverability of ibrutinib with R-mini-CHOP in 80 pts ≥75yrs with DLBCL with a median average relative total dose of 97%; 77% of pts received 6 cycles of R-mini-CHOP despite SAEs in 62% (Verner et al, Haematol Oncol 2019). Here we present the primary efficacy endpoint and key secondary and exploratory endpoints. Methods This was a prospective, multicenter, single-arm, phase 2 study of patients aged ≥75yrs with newly diagnosed DLBCL. Pts received six 21-day cycles of ibrutinib 560mg/d and R-mini-CHOP (Rituximab 375mg/m 2, cyclophosphamide 400mg/m 2, doxorubicin 25mg/m 2, vincristine 1mg on day 1 & prednisone 40mg/m 2 or 100mg/d x 5) followed by an additional two 21-day cycles of rituximab + ibrutinib (or high dose methotrexate for CNS prophylaxis). The efficacy primary endpoint was 2yr OS. Sample size calculations were made using a one-sample two-sided approach to detect a 15% improvement on the fixed reference OS (59%) and PFS (47%) rates (Peyrade et al, Lancet Oncol 2011). Results Eighty pts were recruited from Nov 2015 to Dec 2018. One died prior to receiving treatment and is not included in the analysis. Median age was 82yrs (75-95); 51% female, 81% stage III/IV and 63% IPI 3-5: 47% had a CIRS-G score of ≥6 (range 0-17). On centralized immunohistochemistry (IHC), 57% (45/79) were non-Germinal Centre B cell-like (GCB) subtype; 43% (34/79) were GCB. At a data cut-off of 6June 21, median follow-up was 29.5 months (m) (0.2 to 66.3). Two-year OS was 68% (95% CI 55-77%), not differing significantly from the null hypothesis of 59% (p=0.10), (Figure 1A). Median OS was not reached (NR) (95% CI 34m to NR), and was longer in those with lower IPI (IPI 1-3: NR, IPI 4: 35m, IPI 5: 19m). Two-year PFS was 60% (95% CI 47-70%), significantly different from the reference 47% (p&lt;0.03), (Figure 1B). Median PFS was NR (95% CI 20m to NR). Two-year DFS was 85% (95% CI 60-95%), median NR (95% CI 32m to NR). COO had no impact on either 2yr OS [median GCB NR (95% CI 29m to NR), median non-GCB NR (95% CI 24m to NR) p=0.99] or 2yr PFS [median GCB 39m (95% CI 17m to NR), median non-GCB NR (95% CI 19m to NR) p=0.97]. Cause of death in 28/79 pts (35%) was: 16 progressive lymphoma, 5 infection, 2 respiratory failure, 2 other malignancy, 1 cardiac arrest, 1 intra-abdominal hemorrhage, 1 gastric hemorrhage. At least one adverse event (AE) occurred in 99% pts (78/79): 30% (24/79) grade 1-2, 64% (49/79) grade 3-4, and 6% (5/79) grade 5. Most common grade ≥3 AEs were lung infection (13%), other infections (11%), anemia (11%), febrile neutropenia (9%), thrombocytopenia (9%), and atrial fibrillation (8%). Serious AEs occurred in 67%: most commonly lung infection (11%), atrial fibrillation (9%), fever (9%), and other infection (9%). 12/14 pts with atrial fibrillation/flutter were new onset. Ibrutinib was temporarily ceased in 62% of patients, and permanently ceased in 25%, mostly due to adverse events. As previously reported, the overall response rate on an intention to treat basis was 57/80 (71%) (Verner et al, ASH 2019). Response rates did not differ by cell of origin (COO) (ORR: non-GCB 76%, GCB 68% p=0.44). When recorded, pt's EORTC-QLQ-C30 global health status significantly improved between screening [n=78; mean (SD) 58(25)], end of treatment [n=57; 63(23)] and 18mo post-treatment [n=29; 74(19)] p=0.007. Significant reductions in fatigue, nausea and vomiting, pain, insomnia, appetite loss, constipation and diarrhea were also observed in respondents. There was no impact of CIRS-G score on disease response rate or risk of death. Conclusion The addition of ibrutinib to R-mini-CHOP was deliverable and improved 2-yr PFS compared to R-mini-CHOP alone. However, while there was a trend towards improvement in 2-yr OS, a target 15% increase was not achieved in this small sample size. Despite considerable and not unexpected toxicity in this elderly cohort, the QOL and functional improvements in survivors are also promising. These data support further study of the addition of ibrutinib to R-mini-CHOP in elderly patients with DLBCL. Figure 1 Figure 1. Disclosures Verner: Janssen-Cilag Pty Ltd: Research Funding. Hawkes: Merck KgA: Research Funding; Bristol Myers Squib/Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Specialised Therapeutics: Consultancy; Antigene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Janssen: Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees; Regeneron: Speakers Bureau; Merck Sharpe Dohme: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel and accommodation expenses, Research Funding, Speakers Bureau; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Lee: Roche: Honoraria; BeiGene: Membership on an entity's Board of Directors or advisory committees. Cheah: BMS: Consultancy, Research Funding; Abbvie: Research Funding; Janssen: Consultancy, Honoraria; MSD: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Ascentage Pharma: Consultancy, Honoraria; AstraZeneca: Consultancy, Honoraria; Lilly: Consultancy, Honoraria; TG therapeutics: Consultancy, Honoraria; Beigene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Other: travel, Research Funding. Purtill: Novartis: Honoraria; Gilead: Honoraria; BMS Celgene: Honoraria. Enjeti: Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Speakers Bureau; AbbVie: Honoraria; Sanofi: Honoraria; Astra Zeneca: Honoraria. Curnow: Bayer: Consultancy, Research Funding; Pfizer/BMS: Consultancy, Honoraria; Mylan: Consultancy; Norgine: Consultancy, Honoraria. Butcher: WriteSource: Current Employment, Other: Medical writing for Pharma companies. Not pertinent to this abstract for which author is study Statisticiam. Trotman: JANSSEN: Research Funding; TAKEDA: Research Funding; BMS: Research Funding; PCYC: Research Funding; roche: Research Funding; beigene: Research Funding. OffLabel Disclosure: Ibrutinib is not approved for use in DLBCL