Blockade of the CD47/SIRPα checkpoint axis potentiates the macrophage-mediated anti-tumor efficacy of tafasitamab.

Macrophages are one of the key mediators of the therapeutic effects exerted by monoclonal antibodies, such as the anti-CD19 antibody tafasitamab, approved in combination with lenalidomide for the treatment of relapsed or refractory (r/r) diffuse large B cell lymphoma (DLBCL). However, antibody-dependent cellular phagocytosis (ADCP) in the tumor microenvironment can be counteracted by increased expression of the inhibitory receptor SIRPα on macrophages and its ligand, the immune checkpoint molecule CD47 on tumor cells. The aim of this study was to investigate the impact of the CD47-SIRPα axis on tafasitamabmediated phagocytosis and explore the potential of anti-CD47 blockade to enhance its antitumor activity. Elevated expression of both SIRPα and CD47 was observed in DLBCL patient-derived lymph node biopsies compared to healthy controls. CRISPR-mediated CD47 overexpression impacted tafasitamab-mediated ADCP in vitro and increased expression of SIRPα on macrophages correlated with decreased ADCP activity of tafasitamab against DLBCL cell lines. Combination of tafasitamab and an anti-CD47 blocking antibody enhanced ADCP activity of in vitro generated macrophages. Importantly, tafasitamab-mediated phagocytosis was elevated in combination with CD47 blockade using primary DLBCL cells and patient-derived lymphoma-associated macrophages (LAMs) in an autologous setting. Furthermore, lymphoma cells with low CD19 expression were efficiently eliminated by the combination treatment. Finally, combined treatment of tafasitamab and an anti-CD47 antibody resulted in enhanced tumor volume reduction and survival benefit in lymphoma xenograft mouse models. These findings provide evidence that CD47 blockade can enhance the phagocytic potential of tumor targeting immunotherapies such as tafasitamab and suggest there is value in exploring the combination in the clinic.

Hyper-N-glycosylated SAMD14 and neurabin-I as driver autoantigens of primary central nervous system lymphoma.

To address the role of chronic antigenic stimulation in primary central nervous system lymphoma (PCNSL), we searched for autoantigens and identified sterile α-motif domain containing protein 14 (SAMD14) and neural tissue-specific F-actin binding protein I (neurabin-I) as autoantigenic targets of the B-cell receptors (BCRs) from 8/12 PCNSLs. In the respective cases, SAMD14 and neurabin-I were atypically hyper-N-glycosylated (SAMD14 at ASN339 and neurabin-I at ASN1277), explaining their autoimmunogenicity. SAMD14 and neurabin-I induced BCR pathway activation and proliferation of aggressive lymphoma cell lines transfected with SAMD14- and neurabin-I-reactive BCRs. Moreover, the BCR binding epitope of neurabin-I conjugated to truncated Pseudomonas exotoxin-killed lymphoma cells expressing the respective BCRs. These results support the role of chronic antigenic stimulation by posttranslationally modified central nervous system (CNS) driver autoantigens in the pathogenesis of PCNSL, serve as an explanation for their CNS tropism, and provide the basis for a novel specific treatment approach.

Impact of melatonin receptor deletion on intracellular signaling in spleen cells of mice after polymicrobial sepsis.

OBJECTIVE: Melatonin is known to influence immune functions and to ameliorate outcome after septic challenge but it is unknown whether this is mediated by melatonin receptor activation. This study aimed to elucidate molecular differences in spleen and ex vivo splenocytes of wild-type (WT) and melatonin receptor double knockout mice (KO) after polymicrobial sepsis. SUBJECTS AND METHODS: C3H/HeN wild-type and MT1-/-/MT2-/- mice underwent sham operation or cecum ligation and incision (CLI) and remained anesthetized for 1 h. Splenocytes were isolated and treated in culture with physiological melatonin concentrations (1 nM). RESULTS: Plasma TNFα levels were consistently high after 1 h of CLI. Basal circulating leukocyte numbers were slightly higher in KO animals. We detected transcriptional differences in splenocytes of the knockout strain concerning proinflammatory mediators. Expression levels of IL-1ß, IL-2, CXCR2, L-Selectin, TNFα, CXCL2 and ICAM-1 were strongly increased in splenocytes of KO mice. Splenocytes of KO mice displayed reduced ERK and p38 as well as increased JNK phosphorylation. None of the analyzed factors were influenced by melatonin in the culture medium. CONCLUSIONS: The results of this study indicate an increased proinflammatory status of mice deficient in both membrane-bound melatonin receptors reflected by altered activation of MAPK cascades and transcriptional activation of proinflammatory mediators.

Insertion site of central venous catheter correlates with catheter-related infectious events in patients undergoing intensive chemotherapy.

Patients undergoing intensive chemotherapy are usually in need for central venous catheters (CVC). Due to contradictory study results, relation of insertion site and CVC-associated complication rate in these patients is not clear. We therefore retrospectively analyzed CVC-related data of all patients undergoing intensive chemotherapy with high risk of febrile neutropenia according to NCCN criteria, who received a CVC at our bone marrow transplantation unit between May 2016 and December 2019. In total, 210 patients received 281 CVC. CVC were placed via either the subclavian-vein (SCV, n = 58; 20%) or the internal-jugular-vein (IJV, n = 223; 80%). Median duration of CVC-lifetime and neutropenic days per CVC were comparable between the two groups (IJV vs SCV: 23 days vs 21 days (p = 0.16) and 12 days vs 11 days (p = 0.65)). Both, time to CVC removal due to local inflammation and time to central line-associated bloodstream infection was significantly shorter in patients with SCV catheters (p = 0.013 and p = 0.045). CVC placed in the IJV were associated with significantly less catheter-related infectious events compared with CVC placed in the SCV. This difference was consistent across different subgroups including 88 patients undergoing allogeneic stem cell transplantation.