Prx (peroxiredoxin) 2 protects cells from deleterious oxidative damage. It catalyses the breakdown of hydroperoxides through a highly reactive cysteine residue and has been linked to chaperone activity that promotes cell survival under conditions of oxidative stress. It may also be involved in redox signalling by binding to other proteins. In the present study we have searched for binding partners of Prx2 in H2O2-treated Jurkat and human umbilical vein endothelial cells and discovered that the hyperoxidized form selectively co-precipitated with the protein disulfide-isomerase ERp46. Mutant analyses revealed that loss of the peroxidative cysteine residue of Prx2 also facilitated complex formation with ERp46, even without H2O2 treatment, whereas the resolving cysteine residue of Prx2 was indispensible for the interaction to occur. The complex involved a stable non-covalent interaction that was disassociated by the reduction of intramolecular disulfides in ERp46, or by disruption of the decameric structure of hyperoxidized Prx2. This is the first example of a protein interaction dependent on the hyperoxidized status of a Prx.

There are limited data on post-transplant lymphoproliferative disorder (PTLD) in the era of positron emission tomography (PET) and rituximab (R). Furthermore, there is limited data on the risk of graft rejection with modern practices in reduction in immunosuppression (RIS). We studied 91 patients with monomorphic diffuse large B-cell lymphoma PTLD at 11 Australian centers: median age 52 years, diagnosed between 2004 and 2017, median follow-up 4.7 years (range, 0.5–14.5 y). RIS occurred in 88% of patients. For patients initially treated with R-monotherapy, 45% achieved complete remission, rising to 71% with the addition of rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone (R-CHOP) for those not in complete remission. For patients initially treated with R-CHOP, the complete remission rate was 76%. There was no difference in overall survival (OS) between R-monotherapy and R-chemotherapy patients. There was no difference in OS for patients with systemic lymphoma (n = 68) versus central nervous system (CNS) involvement (n = 23) (3-y OS 72% versus 73%; P = 0.78). Treatment-related mortality was 7%. End of treatment PET was prognostic for patients with systemic lymphoma with longer OS in the PET negative group (3-y OS 91% versus 57%; P = 0.01). Graft rejection occurred in 9% (n = 4 biopsy-proven; n = 4 suspected) during the entire follow-up period with no cases of graft loss. RIS and R-based treatments are safe and effective with a low likelihood of graft rejection and high cure rate for patients achieving complete remission with CNS or systemic PTLD.

Background The treatment landscape for chronic lymphocytic leukaemia (CLL) has significantly changed over the past decade with the advent of targeted therapies. Subsequent improvement in remission rates has been seen in all patient groups, however patients with high-risk genetic features (del17p, TP53 mutation) continue to have poorer outcomes. In such patients, and in multiply relapsed/refractory standard risk patients, allogeneic stem cell transplantation remains a viable management option despite the associated morbidity and mortality. The aim of this study was to examine trends in allogeneic stem cell transplantation for CLL in Australia and New Zealand over the past decade, and to identify predictive factors for overall survival (OS) and progression free survival (PFS). Methods Data was collected through the Australasian Bone Marrow Transplant Recipient Registry (ABMTRR) for patients receiving a first allogeneic stem cell transplantation for CLL, in the absence of Richter's transformation, between January 2009 and December 2018. Transplant outcomes were compared between 2 time periods, 2009-2013 and 2014-2018 using log rank test for survival and Gray's test for cumulative incidence curves. Cox regression analysis was performed to identify factors predictive of survival. Medians are reported with ranges, hazard ratios (HR) and cumulative incidence with 95% confidence intervals (CI). Results A total of 153 patients (75% males) were included. Median age at transplantation was 55 years (range 23-69) with a median time from diagnosis to transplantation of 5.7 years (range 100days - 24.7years). Most patients received reduced intensity or non-myeloablative conditioning (84.3%, n=129) and did not receive T cell depleting therapy (73%, n=94). The median follow up was 5.9 years (range 0.8-11years). Median time to neutrophil engraftment was 16 days (range 6-49) and median time to platelet engraftment was 18 days (range 1-69). At 100 days following transplantation the cumulative incidence of graft failure was 3.9%, CMV reactivation 41% (95% CI 31-50%) and CMV disease 3.2% (95% CI 1-8%). Acute graft versus host disease (aGVHD) grade II-IV occurred in 39% (95% CI 29-49%) of patients and grade III-IV in 17% (95% CI 9-25%). The cumulative incidence of chronic GVHD (cGVHD) was 65% (95% CI 53-76%) at 5 years; extensive cGVHD occurred in 77% of patients with cGVHD. Median OS was 4.3 years (95% CI 3.6-not reached) and PFS was 2.6 years (95% CI 1.7-3.9). The most common contributors to mortality were infection (43%), GVHD (40%) and persistent disease or relapse (24%). In a multivariate analysis active disease at time of transplantation was associated with a worse OS (HR 2.16, 1.01-4.63), however, age, matched sibling donor, myeloablative conditioning and the use of T cell depleting therapies did not have a significant impact. The use of myeloablative conditioning was associated with improved PFS (HR 1.85, 1.1-3.1) in a univariate analysis but lost significance in multivariate analysis. Ninety-seven patients underwent transplantation between 2009-2013 and 56 patients between 2014-2018. There was no statistical difference in patient age, performance status, donor or disease status at transplantation between the groups. Myeloablative conditioning was used in 18.6% and 8.9% (p=0.197), and T cell depleting therapy in 25% and 31% (p=0.58), for the 2009-2013 and 2014-2018 periods respectively. There was a significant improvement in 5-year non-relapse mortality (NRM) from 41.5% (31-52%) to 23.4% (13-29%; p=0.04). Five year OS (46% vs 56%), PFS (36% vs 46%) and relapse rates (21% vs 31%) were not statistically different. Cumulative incidence of both acute and chronic GVHD was reduced in the later cohort; aGVHD 51% (95% CI 34-65%) vs 29% (95% CI 16-43%; p=0.03), cGVHD 76% (95% CI 57-88%) vs 53% (36-66%; p=0.02). Kaplan-meier and cumulative incidence curves for these outcomes are presented in figure 1. Conclusion The number of allogeneic stem cell transplantations performed for CLL has reduced over the past decade in Australasia. There has been an improvement in NRM and incidence of GVHD, however OS and PFS have not significantly changed. This may reflect improved GVHD prophylaxis and management, or advances in supportive care. Further analysis of impact of high-risk genetic factors at transplantation is pending at the time of abstract submission. Figure Disclosures Spencer: Celgene, Janssen and Takeda: Speakers Bureau; AbbVie, Celgene, Haemalogix, Janssen, Sanofi, SecuraBio, Specialised Therapeutics Australia, Servier and Takeda: Consultancy; Amgen, Celgene, Haemalogix, Janssen, Servier and Takeda: Research Funding; AbbVie, Amgen, Celgene, Haemalogix, Janssen, Sanofi, SecuraBio, Specialised Therapeutics Australia, Servier and Takeda: Honoraria. Greenwood:Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Tam:AbbVie: Honoraria, Research Funding; BeiGene: Honoraria; Janssen: Honoraria, Research Funding. Di Ciaccio:Jansen: Honoraria, Other: travel and accomodation grant. Hamad:Novartis: Honoraria; Abbvie: Honoraria.

No abstract

Introduction Post-transplant lymphoproliferative disorders (PTLD) are aggressive lymphomas which occur in solid organ transplant recipients and cause significant mortality. In the era of positron emission tomography (PET) staging and rituximab (R), there is limited real-world data on treatment outcomes and the incidence of graft rejection after reduction in immunosuppression (RIS) has not been well defined. We report real-world outcomes of monomorphic diffuse large B cell lymphoma (DLBCL), the commonest histological subtype of PTLD in which treatment is most likely to be standardised. Methods We conducted a multicentre retrospective study across 11 Australian tertiary referral centres. Inclusion criteria were: (1) age ≥ 18 years with history of solid organ transplant; (2) a diagnosis of monomorphic DLBCL PTLD between January 2004 and December 2017; (3) staging with PET. We examined responses based on treatment: (1) 'R-primary' was defined as patients receiving initial rituximab monotherapy followed by further rituximab monotherapy for patients in remission or R-CHOP chemotherapy for patients with persistent or progressive disease; (2) 'R-chemotherapy' was defined as patients who received rituximab-based chemotherapy at diagnosis. Response assessment was defined according to current international lymphoma criteria (complete metabolic remission (CMR) = Deauville score 1-3). We examined the incidence of clinical and biopsy-proven graft rejection during and after PTLD diagnosis (early <1 year; late ≥1 year). Survival was analysed using the Kaplan-Meier method with the log rank test used to compare groups. Results 91 DLBCL patients were identified. The median follow-up of living patients was 4.7 years (range 0.5-14.5 years). Baseline characteristics for all patients are shown in Table 1. Management approaches: Reduction in immunosuppression (RIS) was used in 88% of patients and rituximab (R) +/- chemotherapy in almost all patients (98%, n=89). Rituximab monotherapy (R-primary) was the first treatment in 24 patients (35%). Of these, 20 had PET restaging after rituximab and 9 patients (45%) achieved CMR and did not require chemotherapy. CMR rate rose to 71% with the subsequent addition of R-CHOP in R-primary non-responders. For patients initially treated with R-CHOP, the CMR rate was 76%. The incidence of graft rejection was 9% for the entire duration of follow up (n=4 biopsy-proven; n=4 clinically suspected) with 3 cases occurring within one year of PTLD diagnosis (Table 2). Survival and Prognostic Factors For the entire cohort, 3-y OS and PFS were 72% and 69%, respectively. There was no significant difference in OS between patients treated with an R-primary vs R-chemotherapy approach (P=0.13). Treatment-related mortality (TRM) was 7% with no significant difference between R-primary and R-chemotherapy approach (p=0.97). Outcomes for patients without CNS involvement (n=68) were comparable to patients with CNS involvement (n=23): 3-y OS 72.5% non-CNS vs 73.1% CNS; (P=0.78) - Figure 1. In multivariate analysis, elevated LDH (HR=3.58, P=0.025 [95% CI 1.17-10.8]) and ECOG ≥2 (HR=3.46, P=0.006 [95% CI 1.43-8.33]) were identified as predictors of worse OS. End of Treatment (EoT) PET imaging A total of 60 patients (66%) had EoT PET. Reasons for not performing an EoT PET (n=31) were: 7 MRI scans for CNS disease, 2 CT scans without PET, 10 patients without imaging (6 PD, 4 TRM), 12 missing data. Achieving CMR at EoT PET was predictive of OS (3-year OS PET negative 92.9% vs PET positive 51.4%; P=0.035) and only 5% of these patients relapsed (Figure 2). Conclusions In one of the largest real-world assessments of monomorphic DLBCL PTLD in the modern era of rituximab and PET imaging our data demonstrate: (1) similar response rate, OS and TRM compared to the PTLD-1 trial (Trappe et al, 2017); (2) the safety and efficacy of an R-primary approach; (3) similar OS for patients with CNS involvement compared to those with systemic lymphoma; (4) lower incidence of graft rejection than previously reported; and (5) achieving CMR at EOT PET is predictive of OS. This demonstrates that RIS and rituximab-based treatment is safe with a low likelihood of graft rejection and effective with a high cure rate for patients achieving CMR. Disclosures Tobin: Gilead: Research Funding. Hamad:Novartis: Honoraria; Abbvie: Honoraria. Talaulikar:Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Cheah:Celgene, F. Hoffmann-La Roche, Abbvie, MSD: Research Funding; Celgene, F. Hoffmann-La Roche, MSD, Janssen, Gilead, Ascentage Pharma, Acerta, Loxo Oncology, TG therapeutics: Honoraria. Lee:Celgene/BMS: Consultancy; Amgen: Consultancy; Janssen: Consultancy. Strasser:Gilead Sciences: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer Healthcare: Honoraria, Membership on an entity's Board of Directors or advisory committees; Ispen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Eisai: Honoraria, Membership on an entity's Board of Directors or advisory committees; MSD: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; CSL Behring: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees. Mollee:Pfizer: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Caelum: Membership on an entity's Board of Directors or advisory committees.