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. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13046-022-02256-x

Glucocorticosteroids in Nano-Sterically Stabilized Liposomes Are Efficacious for Elimination of the Acute Symptoms of Experimental Cerebral Malaria

Cerebral malaria is the most severe complication of Plasmodium falciparum infection, and a leading cause of death in children under the age of five in malaria-endemic areas. We report high therapeutic efficacy of a novel formulation of liposome-encapsulated water-soluble glucocorticoid prodrugs, and in particular beta-methasone hemisuccinate (BMS), for treatment of experimental cerebral malaria (ECM), using the murine P. berghei ANKA model. BMS is a novel derivative of the potent steroid beta-methasone, and was specially synthesized to enable remote loading into nano-sterically stabilized liposomes (nSSL), to form nSSL-BMS. The novel nano-drug, composed of nSSL remote loaded with BMS, dramatically improves drug efficacy and abolishes the high toxicity seen upon administration of free BMS. nSSL-BMS reduces ECM rates in a dose-dependent manner and creates a survival time-window, enabling administration of an antiplasmodial drug, such as artemisone. Administration of artemisone after treatment with the nSSL-BMS results in complete cure. Treatment with BMS leads to lower levels of cerebral inflammation, demonstrated by changes in cytokines, chemokines, and cell markers, as well as diminished hemorrhage and edema, correlating with reduced clinical score. Administration of the liposomal formulation results in accumulation of BMS in the brains of sick mice but not of healthy mice. This steroidal nano-drug effectively eliminates the adverse effects of the cerebral syndrome even when the treatment is started at late stages of disease, in which disruption of the blood-brain barrier has occurred and mice show clear signs of neurological impairment. Overall, sequential treatment with nSSL-BMS and artemisone may be an efficacious and well-tolerated therapy for prevention of CM, elimination of parasites, and prevention of long-term cognitive damage

Survival rates after early treatment with 10 mg/kg free or nSSL-encapsulated MPS (upper graph) or BMS (lower graph).

<p>Representative results for ICR mice infected with PbA are presented. Arrows denote treatment administration. ECM prevention is reflected in longer survival times, due to the development of severe anemic malaria, and as a result creation of a survival time-window for anti-plasmodial administration. Significant differences in survival were seen between non-treated and nSSL-MPS-treated groups (p = 0.01) and between non-treated mice and mice administered free or nSSL-BMS (p<0.01).</p

Characterization of nSSL before and after GC loading.

<p>Values shown in each category are the average±SD for at least 10 formulations (13 empty nSSL, 27 nSSL-BMS, and 17 nSSL-MPS formulations). No significant differences were observed when comparing size according to intensity, number, or volume. No significant differences were observed when comparing nSSL-MPS and nSSL-BMS. PdI: an indication of size distribution variance between different batches prepared. A low PdI (<0.2) indicates that the sample is monodispersed.% drug encapsulated  = 100×([drug]/[lipid]_{after Dowex anion exchanger})/([drug]/[lipid]_{after dialysis}).</p

The effect of nSSL-BMS treatment at late stages of ECM, followed by artemisone.

<p>PbAus-infected C57Bl/6 mice (n = 10 per group, non-treated; n = 6 per group, nSSL-BMS) were administered 5% dextrose or 20 mg/kg nSSL-BMS (arrows) every other day, starting on day 5p.i., followed by 2×10 mg/kg/d artemisone after the cerebral phase, on days 11–15 p.i. (double arrows). No effect on the development of parasitemia was observed following administration of 5% dextrose. Administration of nSSL-BMS significantly reduced clinical score when started on day 5 p.i. or day 6 p.i. (p<0.001, p<0.05 vs. no treatment, respectively) and increased survival (p<0.01 and p<0.001 vs. non-treated), creating a time-window for antiplasmodial treatment and cure. *Day 15 p.i. nSSL-BMS: n = 6 (days 5,7,9 p.i. and days 6,8 p.i.).</p

Scoring of clinical signs of ECM.

<p>Scoring of clinical signs of ECM.</p

Effect of sequential steroid-artemisone treatment on the development of infection.

<p>PbAus-infected C57Bl/6 mice (n = 10 per group) were treated with 10 mg/kg free or nSSL-BMS on days 3, 5, 7, and 9 post-inoculation. Although parasitemias were not affected (p>0.05, all groups), treatment led to reduced clinical scores (p<0.05, non-treated vs. free BMS; p<0.001, vs. nSSL-BMS, days 1–12 p.i.), an effect more pronounced in liposome-treated mice (p<0.05, free vs. nSSL). Administration of 2×20 mg/kg/d artemisone on days 11–15p.i. led to cure. *One mouse (of the total 17 administered artemisone) relapsed and died of ECM. Arrows represent free or nSSL-BMS injections; double arrows represent artemisone injections.</p

Levels of BMS originating from nSSL-BMS or free BMS in tissues of naive healthy mice and mice with ECM.

<p>Mice at initial clinical stages of ECM were injected (on day 6 p.i.) with either free or nSSL-BMS. Healthy mice were injected with nSSL-BMS. *n.d, not done.</p

Hemorrhages post-PbAus infection and following free BMS or nSSL-BMS administration.

<p>H&E staining: representative pictures depicting hemorrhage size, day 9 p.i. (magnification ×20). No hemorrhages were observed in the brains of healthy mice. PbAus-infected C57Bl/6 mice were administered placebo (5% dextrose, n = 22), 20 mg/kg free BMS (n = 17) or nSSL-BMS (n = 18) on days 3, 5, 7, and 9 p.i. Survival rates on day 13p.i., at the end of the cerebral phase, were 0 in the placebo group and 12% in the free BMS group, vs. 88% in the nSSL-BMS group.</p

Structures of the glucocorticoid prodrugs methylprednisolone hemisuccinate (MPS, left) and β-methasone hemisuccinate (BMS, right).

<p>Both compounds are amphipathic weak acids suitable for loading into nSSL.</p