DSP107 combines inhibition of CD47/SIRPα axis with activation of 4-1BB to trigger anticancer immunity.

BACKGROUND: Treatment of Diffuse Large B Cell Lymphoma (DLBCL) patients with rituximab and the CHOP treatment regimen is associated with frequent intrinsic and acquired resistance. However, treatment with a CD47 monoclonal antibody in combination with rituximab yielded high objective response rates in patients with relapsed/refractory DLBCL in a phase I trial. Here, we report on a new bispecific and fully human fusion protein comprising the extracellular domains of SIRPα and 4-1BBL, termed DSP107, for the treatment of DLBCL. DSP107 blocks the CD47:SIRPα 'don't eat me' signaling axis on phagocytes and promotes innate anticancer immunity. At the same time, CD47-specific binding of DSP107 enables activation of the costimulatory receptor 4-1BB on activated T cells, thereby, augmenting anticancer T cell immunity. METHODS: Using macrophages, polymorphonuclear neutrophils (PMNs), and T cells of healthy donors and DLBCL patients, DSP107-mediated reactivation of immune cells against B cell lymphoma cell lines and primary patient-derived blasts was studied with phagocytosis assays, T cell activation and cytotoxicity assays. DSP107 anticancer activity was further evaluated in a DLBCL xenograft mouse model and safety was evaluated in cynomolgus monkey. RESULTS: Treatment with DSP107 alone or in combination with rituximab significantly increased macrophage- and PMN-mediated phagocytosis and trogocytosis, respectively, of DLBCL cell lines and primary patient-derived blasts. Further, prolonged treatment of in vitro macrophage/cancer cell co-cultures with DSP107 and rituximab decreased cancer cell number by up to 85%. DSP107 treatment activated 4-1BB-mediated costimulatory signaling by HT1080.4-1BB reporter cells, which was strictly dependent on the SIRPα-mediated binding of DSP107 to CD47. In mixed cultures with CD47-expressing cancer cells, DSP107 augmented T cell cytotoxicity in vitro in an effector-to-target ratio-dependent manner. In mice with established SUDHL6 xenografts, the treatment with human PBMCs and DSP107 strongly reduced tumor size compared to treatment with PBMCs alone and increased the number of tumor-infiltrated T cells. Finally, DSP107 had an excellent safety profile in cynomolgus monkeys. CONCLUSIONS: DSP107 effectively (re)activated innate and adaptive anticancer immune responses and may be of therapeutic use alone and in combination with rituximab for the treatment of DLBCL patients.

BL-8040 CXCR4 antagonist is safe and demonstrates antileukemic activity in combination with cytarabine for the treatment of relapsed/refractory acute myelogenous leukemia: An open-label safety and efficacy phase 2a study.

BACKGROUND: CXCR4 mediates the retention and survival of acute myelogenous leukemia blasts in bone marrow and contributes to their resistance to chemotherapy. The authors evaluated a combination of the high-affinity CXCR4 antagonist BL-8040 with high-dose cytarabine (HiDAC) chemotherapy in a phase 2a study of patients with relapsed and refractory AML. METHODS: Forty-two patients received treatment with BL-8040 monotherapy for 2 days followed by a combination of BL-8040 with HiDAC for 5 days. Six escalating BL-8040 dose levels were investigated (0.5, 0.75, 1.0, 1.25, 1.5, and 2.0 mg/kg), and 1.5 mg/kg was selected as the dose for the expansion phase (n = 23). RESULTS: BL-8040 in combination with HiDAC was safe and well tolerated at all dose levels. Clinical response was observed with BL-8040 doses ≥1.0 mg/kg. The composite response rate (complete remissions plus complete remissions with incomplete hematologic recovery of platelets or neutrophils) was 29% (12 of 42) in all patients and 39% (9 of 23) in the 1.5-mg/kg phase. The median overall survival was 8.4 months for all patients, 10.8 months in the 1.5-mg/kg phase, and 21.8 months for responding patients in the 1.5-mg/kg cohort. Two days of BL-8040 monotherapy triggered the mobilization of blasts into peripheral blood, with significantly higher mean fold-changes in responders versus nonresponders. This was accompanied by a decrease in bone marrow blasts. CONCLUSIONS: The current results demonstrate the efficacy of CXCR4 targeting with BL-8040 and support continued clinical development in acute myelogenous leukemia.

Aleglitazar, a balanced PPARα/γ agonist, has no clinically relevant pharmacokinetic interaction with high-dose atorvastatin or rosuvastatin.

BACKGROUND: Aleglitazar, a dual PPAR-α/γ agonist, combines the lipid benefits of fibrates and the insulin-sensitizing benefits of thiazolidinediones. OBJECTIVE: To investigate the pharmacokinetic effects of co-administration of atorvastatin or rosuvastatin with aleglitazar. RESEARCH DESIGN AND METHODS: In a two-cohort, open-label, randomised, three-period crossover study, 44 healthy subjects received once-daily oral doses of aleglitazar 300 µg, statin (atorvastatin 80 mg or rosuvastatin 40 mg) and aleglitazar co-administered with each statin for 7 days. Plasma concentrations of each drug were measured and pharmacokinetic parameters determined on day 7 in each period. MAIN OUTCOME MEASURES: Peak observed plasma concentration (C(max)) and total exposures (AUC(0 - 24)) of aleglitazar, atorvastatin and rosuvastatin. RESULTS: C(max) and AUC(0 - 24) to aleglitazar were similar, whether administered alone or in combination with a statin. Total exposure to either statin was unaffected by co-administration with aleglitazar. C(max) treatment ratios for both statins exceeded the conventional no-effect boundary (1.25) when administered with aleglitazar. CONCLUSIONS: Co-administration of aleglitazar with a statin does not alter the pharmacokinetic profile of either drug.

Evidence for incorporation of free-floating mesothelial cells as a mechanism of serosal healing.

Regeneration of the mesothelium is unlike that of other epithelial-like surfaces, as healing does not occur solely by centripetal migration of cells from the wound edge. The mechanism of repair of mesothelium is controversial, but it is widely accepted, without compelling evidence, that pluripotent cells beneath the mesothelium migrate to the surface and differentiate into mesothelial cells. In this study we examined an alternative hypothesis, using in vivo cell-tracking studies, that repair involves implantation, proliferation and incorporation of free-floating mesothelial cells into the regenerating mesothelium. Cultured mesothelial cells, fibroblasts and peritoneal lavage cells were DiI- or PKH26-PCL-labelled and injected into rats immediately following mesothelial injury. Implantation of labelled cells was assessed on mesothelial imprints using confocal microscopy, and cell proliferation was determined by proliferating cell nuclear antigen immunolabelling. Incorporation of labelled cells, assessed by the formation of apical junctional complexes, was shown by confocal imaging of zonula occludens-1 protein. Labelled cultured mesothelial and peritoneal lavage cells, but not cultured fibroblasts, implanted onto the wound surface 3, 5 and 8 days after injury. These cells proliferated and incorporated into the regenerated mesothelium, as demonstrated by nuclear proliferating cell nuclear antigen staining and membrane-localised zonula occludens-1 expression, respectively. Furthermore, immunolocalisation of the mesothelial cell marker HBME-1 demonstrated that the incorporated, labelled lavage-derived cells were mesothelial cells and not macrophages as it had previously been suggested. This study has clearly shown that serosal healing involves implantation, proliferation and incorporation of free-floating mesothelial cells into the regenerating mesothelium.