Cinrebafusp alfa (PRS 343) is a high-affinity CD137/HER2 bispecific anticalcin drug. Cinrebafusp alfa binds recombinant human HER2 (Kd=0.3 nM) and human monomeric CD137 (4-1BB; Kd=5 nM). Cinrebafusp alfa promotes T cell costimulation through tumor-localized HER2-dependent 4-1BB aggregation and activation, further enhancing T cell receptor-mediated activity and leading to tumor destruction. Cinrebafusp alfa may be used in HER2+ solid tumor research.

Physicochemical Properties

CAS #	2218515-90-1
Appearance	Colorless to light yellow liquid
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

Targets	4-1BB 5 nM (Kd) HER2 0.3 nM (Kd)
ln Vitro	In the FACS experiment, cinrebafusp alfa (PRS 343) binds to CHO cells transfected with human 4-1BB and HER2-expressing MCF-7 cells, with EC50s of 7.4 nmol/L and 6.2 nmol/L, respectively [1].
ln Vivo	In a humanized mouse model transplanted with HER2-positive SK-OV-3 tumor cells, cinrebafusp alfa (PRS 343; 0.2-10 mg/kg; intravenously; once weekly; for 20 days) caused tumor growth inhibition and tumor-infiltrating lymphocytes increased in a dose-dependent manner [1]. For male CD-1 mice, cinrebafusp alfa (10 mg/kg; IV; single dose) has a terminal elimination half-life of longer than 14 days. In male cynomolgus monkeys, the terminal elimination half-life of cinrebafusp alfa (3 mg/kg; IV; single dose) is roughly 4 days [1].
Animal Protocol	Animal/Disease Models: SK-OV-3 ovarian cancer model in human PBMC-reconstituted NOG female mice, ages 5-7 weeks[1] Doses: 0.2, 1 , 5, 10 mg/kg Route of Administration: IV; once weekly; for 20 day Experimental Results: Displayed dose-dependent antitumor efficacy with doses ranging from 4 μg to 100 μg (approximately 0.2 mg/kg to 5 mg/kg), while the 200 -μg dose (approximately 10 mg/kg) did not further enhance tumor regression. Led to a significant increase in human CD45+ lymphocytes in tumor tissue. Animal/Disease Models: Male CD-1 mice[1] Doses: 10 mg/kg (pharmacokinetic/PK Analysis ) Route of Administration: IV; single dose Experimental Results: Had the terminal elimination half-life of >14 days.
References	[1]. Tumor-Localized Costimulatory T-Cell Engagement by the 4-1BB/HER2 Bispecific Antibody-Anticalin Fusion PRS-343. Clin Cancer Res. 2019 Oct 1;25(19):5878-5889. [2]. 525O A phase I dose escalation study of PRS-343, a HER2/4-1BB bispecific molecule, in patients with HER2-positive malignancies. ABSTRACT ONLY, VOLUME 31, SUPPLEMENT 4, S462-S463, SEPTEMBER 01, 2020.

Solubility Data

Solubility (In Vitro)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Solubility (In Vivo)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples. Injection Formulations (e.g. IP/IV/IM/SC) Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] *Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline) Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline) Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline) Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil) Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Oral Formulations Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). Oral Formulation 3: Dissolved in PEG400 Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose Oral Formulation 6: Mixing with food powders Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.  (Please use freshly prepared in vivo formulations for optimal results.)