CT109-SN-38, a Novel Antibody-drug Conjugate with Dual Specificity for CEACAM5 and 6, Elicits Potent Killing of Pancreatic Cancer Cells.

BACKGROUND: CEACAM5 and CEACAM6 are glycosylphosphatidylinositol (GPI)- linked members of the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family, which are frequently upregulated in epithelial cancers where they contribute to invasion, metastasis, immune evasion, and resistance to anoikis. CT109 is a novel antibody with dual specificity to both CEACAM5 and 6. OBJECTIVE: In this study, we aimed to perform the preclinical characterization of CT109 and antibody- drug conjugate (ADCs) derivatives of CT109, focusing on CT109-SN-38. METHODS: CT109's cognate epitope was characterized by scanning mutagenesis. CT109 specificity and internalization kinetics were assessed by immunoblot and flow cytometry, respectively. Cognate antigen expression prevalence in colorectal cancer and normal tissue arrays was determined by immunohistochemistry. CT109 conjugations were generated by the reaction of reduced CT109 cysteines with maleimide-functionalized payload linkers. In vitro cytotoxic activity of CT109 ADCs was characterized on antigen-positive and negative pancreatic ductal adenocarcinoma cell (PDAC) lines using a luminometric viability assay. In vivo efficacy of CT109-SN-38 was assessed on a PDAC tumor xenograft model at 10 and 25 mg/kg concentrations. RESULTS: CT109 showed to bind a glycoepitope centered on N309. CT109 is internalized in the CEACAM5+/CEACAM6+ double-positive PDAC line, BxPC-3, with a t1/2 of 2.3 hours. CT109 ADCs elicit a dose and antigen-dependent cytotoxic effect, with CT109-SN-38 exhibiting an IC50 value of 21 nM in BxPC-3 cells. In a BxPC-3 tumor xenograft model, CT109-SN-38 reduced tumor growth and induced regression in 3/10 mice at 25 mg/kg concentration. CONCLUSIONS: These data suggest that further preclinical and clinical development of CT109-SN-38 is warranted.

SERPIN-Derived Small Peptide (SP16) as a Potential Therapeutic Agent against HIV-Induced Inflammatory Molecules and Viral Replication in Cells of the Central Nervous System.

Despite the success of combined antiretroviral therapy (cART) increasing the survival rate in human immunodeficiency virus (HIV) patients, low levels of viremia persist in the brain of patients leading to glia (microglia and astrocytes)-induced neuroinflammation and consequently, the reactivation of HIV and neuronal injury. Here, we tested the therapeutic efficacy of a Low-Density Lipoprotein Receptor-Related Protein 1 (LRP-1) agonistic small peptide drug (SP16) in attenuating HIV replication and the secretion of inflammatory molecules in brain reservoirs. SP16 was developed by Serpin Pharma and is derived from the pentapeptide sequence of the serine protease inhibitor alpha-1-antitrypsin (A1AT). The SP16 peptide sequence was subsequently modified to improve the stability, bioavailability, efficacy, and binding to LRP-1; a scavenger regulatory receptor that internalizes ligands to induce anti-viral, anti-inflammatory, and pro-survival signals. Using glial cells infected with HIV, we showed that: (i) SP16 attenuated viral-induced secretion of pro-inflammatory molecules; and (ii) SP16 attenuated viral replication. Using an artificial 3D blood-brain barrier (BBB) system, we showed that: (i) SP16 was transported across the BBB; and (ii) restored the permeability of the BBB compromised by HIV. Mechanistically, we showed that SP16 interaction with LRP-1 and binding lead to: (i) down-regulation in the expression levels of nuclear factor-kappa beta (NF-κB); and (ii) up-regulation in the expression levels of Akt. Using an in vivo mouse model, we showed that SP16 was transported across the BBB after intranasal delivery, while animals infected with EcoHIV undergo a reduction in (i) viral replication and (ii) viral secreted inflammatory molecules, after exposure to SP16 and antiretrovirals. Overall, these studies confirm a therapeutic response of SP16 against HIV-associated inflammatory effects in the brain.

Safety, Tolerability, and Effects of a Single Subcutaneous Administration of SP16 - a SERPIN-like, Small Peptide Agonist of the Low-Density Lipoprotein-like Receptor 1- on the Acute Inflammatory Response in Patients With ST-Segment Elevation Myocardial Infarction.

BACKGROUND: Modulation of the inflammatory response is a promising therapeutic strategy in acute myocardial infarction. The novel approach is based on the anti-inflammatory and cytoprotective properties mediated by the engagement of the low-density lipoprotein‒related protein 1 (LRP1) receptor. SERPIN peptide 16 (SP16) is a synthetic, selective LRP1 agonist. We herein present the results of a study with a single subcutaneous administration of SP16 in 10 patients with STEMI, to appraise its safety and tolerability and explore the effects on the acute inflammatory response, infarct size, and cardiac function. METHODS: Ten patients with ST-segment elevation myocardial infarction (STEMI) were enrolled within 12 hours of symptoms onset and 6 hours of percutaneous coronary intervention in a single-center, single-arm, open-label study of a single subcutaneous administration of SP16 (0.2 mg/kg). Serial clinical biomarkers and echocardiography data were collected up to 12 months. The data are presented separately for the treatment group and compared with historical controls from a placebo-treated arm in a recently completed clinical trial (N = 28) with similar enrollment criteria. RESULTS: All ten patients with STEMI received subcutaneous administration of SP16, 381 [272-478] minutes after percutaneous coronary intervention, without any treatment-related adverse events. The area under the curve for C-reactive protein was 133 [46-528] mg·d/L in the SP16-treated group versus 286 [141-581] mg·d/L in the historical placebo-treated group ( P = 0.161). The area under the curve for creatine kinase-myocardial band was 1432 [675-3089] ng·d/mL in the SP16-treated group versus 2367 [830-4750] ng·d/mL in the historical placebo-treated patients ( P = 0.428). Left ventricular ejection fraction was 46% [39-54] at baseline and 51% [46-58] at 1 year follow-up in SP16-treated patients (interval change 5% [-0.3% to +9%] P = 0.05) and 44% [38%-56%] at baseline and 53% [43%-59%] at 1 year follow-up in historical placebo-treated patients (interval change 3% [-5% to 10%], P = 0.305). CONCLUSION: A single subcutaneous administration of SP16, a synthetic targeted LRP1 agonist, was safe and well-tolerated in patients with STEMI. A trend toward reduction in the inflammatory response and infarct size with SP16 was noted; however, the sample size for this study was not based on formal statistical criteria. More extensive studies are planned to determine the clinical efficacy of SP16 in STEMI.NCT: NCT04225533.

Regulation of ghrelin structure and membrane binding by phosphorylation.

The peptide hormone ghrelin requires Ser-3 acylation for receptor binding, orexigenic and anti-inflammatory effects. Functions of desacylghrelin are less well understood. In vitro kinase assays reveal that the evolutionarily conserved Ser-18 in the basic C-terminus is an excellent substrate for protein kinase C. Circular dichroism reveals that desacylghrelin is approximately 12% helical in aqueous solution and approximately 50% helical in trifluoroethanol. Ser-18-phosphorylation, Ser-18-Ala substitution, or Ser-3-acylation reduces the helical character in trifluoroethanol to approximately 24%. Both ghrelin and desacylghrelin bind to phosphatidylcholine:phosphatidylserine sucrose-loaded vesicles in a phosphatidylserine-dependent manner. Phosphoghrelin and phosphodesacylghrelin show greatly diminished phosphatidylserine-dependent binding. These results are consistent with binding of ghrelin and desacylghrelin to acidic lipids via the basic face of an amphipathic helix with Ser-18 phosphorylation disrupting both helical character and membrane binding.