CL2A-SN-38, an SN-38 (topoisomerase-I inhibitor) analogue, is a peptide-based drug linker used to synthesize antibody drug conjugates (ADC). It is composed of a potent DNA Topoisomerase I inhibitor SN-38 and a linker CL2A, which provides significant and specific anticancer effects against a panel of human solid tumors. CL2A-SN-38 is conjugated to the anti-Trop-2-humanized antibody, SN-38-anti-Trop-2 antibody-drug conjugate (ADC) against several human solid tumor types, provides significant and specific antitumor effects against a range of human solid tumor types.
Physicochemical Properties
| Molecular Formula | C77H101CL4N11O26 |
| Molecular Weight | 1738.4960 |
| Exact Mass | 1479.68 |
| Elemental Analysis | C, 53.20; H, 5.86; Cl, 8.16; N, 8.86; O, 23.93 |
| CAS # | 1279680-68-0 |
| Related CAS # | 1279680-68-0 |
| PubChem CID | 89983570 |
| Appearance | Light yellow to yellow solid powder |
| LogP | -0.1 |
| Hydrogen Bond Donor Count | 6 |
| Hydrogen Bond Acceptor Count | 26 |
| Rotatable Bond Count | 50 |
| Heavy Atom Count | 106 |
| Complexity | 2930 |
| Defined Atom Stereocenter Count | 2 |
| SMILES | CCC1=C2CN3C(=CC4=C(C3=O)COC(=O)[C@@]4(CC)OC(=O)OCC5=CC=C(C=C5)NC(=O)[C@H](CCCCN)NC(=O)COCC(=O)NCCOCCOCCOCCOCCOCCOCCOCCOCCN6C=C(N=N6)CNC(=O)C7CCC(CC7)CN8C(=O)C=CC8=O)C2=NC9=C1C=C(C=C9)O |
| InChi Key | WWSNNYDLXHTRLZ-JGQYWRMXSA-N |
| InChi Code | InChI=1S/C73H97N11O22.2C2H2Cl2O2/c1-3-55-56-39-54(85)16-17-60(56)79-67-57(55)44-83-62(67)40-59-58(70(83)92)46-104-71(93)73(59,4-2)106-72(94)105-45-50-10-14-52(15-11-50)77-69(91)61(7-5-6-20-74)78-64(87)48-103-47-63(86)75-21-23-95-25-27-97-29-31-99-33-35-101-37-38-102-36-34-100-32-30-98-28-26-96-24-22-82-43-53(80-81-82)41-76-68(90)51-12-8-49(9-13-51)42-84-65(88)18-19-66(84)89;2*3-1(4)2(5)6/h10-11,14-19,39-40,43,49,51,61,85H,3-9,12-13,20-38,41-42,44-48,74H2,1-2H3,(H,75,86)(H,76,90)(H,77,91)(H,78,87);2*1H,(H,5,6)/t49?,51?,61-,73-;;/m0../s1 |
| Chemical Name | 4-((S)-2-(4-aminobutyl)-35-(4-((4-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)cyclohexane-1-carboxamido)methyl)-1H-1,2,3-triazol-1-yl)-4,8-dioxo-6,12,15,18,21,24,27,30,33-nonaoxa-3,9-diazapentatriacontanamido)benzyl ((S)-4,11-diethyl-9-hydroxy-3,14-dioxo-3,4,12,14-tetrahydro-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinolin-4-yl) carbonate bis(2,2-dichloroacetate) |
| Synonyms | CL2A-SN-38; CL2A-SN 38; CL2A-SN38; CL2ASN-38; CL2A SN 38; CL2ASN38; CL2A-SN38 DCA salt; CL2A-SN38 dichloroacetic acid. |
| 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 Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), away from moisture and light. |
| 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 | Camptothecins/DNA Topoisomerase I |
| ln Vitro | Two SN-38 derivatives, CL2-SN-38 and CL2A-SN-38, were conjugated to the anti-Trop-2-humanized antibody, hRS7. The immunoconjugates were characterized in vitro for stability, binding, and cytotoxicity [1]. |
| ln Vivo | In mice bearing human colon (COLO 205) or pancreatic (Capan-1) tumor xenografts, CL2A-SN-38 in combination with the anti-Trop-2 humanized antibody hRS7 (intraperitoneal injection, 0.2 or 0.4 mg/kg, twice weekly, 4 weeks) can both significantly inhibit tumor growth[1]. |
| Enzyme Assay | Preparations of CL2A-SN-38 (M.W. 1480) and its hRS7 conjugate, and stability, binding and cytotoxicity studies, were conducted as described previously, and are presented in the Supplemental Data. Cell lysates were prepared and immunoblotting for p21Waf1/Cip, p53, and PARP (poly-ADP-ribose polymerase) was done as described in Supplemental Data. Concentrations, timing, and primary antibodies are shown in the figure legends [1]. |
| Cell Assay | All human cancer cell lines used in this study were purchased from the American Type Culture Collection. These include Calu-3 (non-small cell lung carcinoma), SK-MES-1 (squamous cell lung carcinoma), COLO 205 (colonic adenocarcinoma), Capan-1 and BxPC-3 (pancreatic adenocarcinomas), and PC-3 (prostatic adenocarcinomas). Humanized RS7 IgG and control humanized anti-CD20 (hA20 IgG, veltuzumab) and anti-CD22 (hLL2 IgG, epratuzumab) antibodies were prepared at Immunomedics, Inc. Irinotecan (20 mg/mL) was obtained from Hospira, Inc.[1]. |
| Animal Protocol |
For all animal studies, the doses of SN-38 immunoconjugates and irinotecan are shown in SN-38 equivalents. Based on a mean SN-38/IgG substitution ratio of six, a dose of 500 μg ADC to a 20-gram mouse (25 mg/kg) contains 0.4 mg/kg of SN-38. Irinotecan doses are likewise shown as SN-38 equivalents (i.e., 40 mg irinotecan/kg is equivalent to 24 mg/kg of SN-38). NCr female athymic nude (nu/nu) mice, 4–8 weeks old, and male Swiss-Webster mice, 10 weeks old, were purchased from Taconic Farms (Germantown, NY). All animal studies were approved by the Center for Molecular Medicine and Immunology’s Institutional Animal Care and Use Committee (IACUC). Tolerability studies were performed in Cynomolgus monkeys (Macaca fascicularis; 2.5–4 kg male and female) by SNBL USA, Ltd. after approval by SNBL USA’s IACUC. Animals were implanted subcutaneously with different human cancer cell lines as described in the Supplemental Information. Tumor volume (TV) was determined by measurements in two dimensions using calipers, with volumes defined as: L x w2/2, where L is the longest dimension of the tumor and w the shortest. Tumors ranged in size between 0.10 to 0.47 cm3 when therapy began. Treatment regimens, dosages, and number of animals in each experiment are described in the Results. The lyophilized hRS7-CL2A-SN-38 and control ADC were reconstituted and diluted as required in sterile saline. All reagents were administered intraperitoneally (0.1 mL), except irinotecan, which was administered intravenously. The dosing regimen was influenced by our prior investigations, where the ADC was given every 4 days or twice weekly for varying lengths of time. This dosing frequency reflected a consideration of the conjugate’s serum half-life in vitro, in order to allow a more continuous exposure to the ADC. |
| References |
[1]. Humanized anti-Trop-2 IgG-SN-38 conjugate for effective treatment of diverse epithelial cancers: preclinical studies in human cancer xenograft models and monkeys. Clin Cancer Res. 2011 May 15;17(10):3157-69. |
| Additional Infomation |
Purpose: Evaluate the efficacy of an SN-38-anti-Trop-2 antibody-drug conjugate (ADC) against several human solid tumor types, and to assess its tolerability in mice and monkeys, the latter with tissue cross-reactivity to hRS7 similar to humans. Experimental design: Two SN-38 derivatives, CL2-SN-38 and CL2A-SN-38, were conjugated to the anti-Trop-2-humanized antibody, hRS7. The immunoconjugates were characterized in vitro for stability, binding, and cytotoxicity. Efficacy was tested in five different human solid tumor-xenograft models that expressed Trop-2 antigen. Toxicity was assessed in mice and in Cynomolgus monkeys. Results: The hRS7 conjugates of the two SN-38 derivatives were equivalent in drug substitution (∼ 6), cell binding (K(d) ∼ 1.2 nmol/L), cytotoxicity (IC(50) ∼ 2.2 nmol/L), and serum stability in vitro (t/(½) ∼ 20 hours). Exposure of cells to the ADC demonstrated signaling pathways leading to PARP cleavage, but differences versus free SN-38 in p53 and p21 upregulation were noted. Significant antitumor effects were produced by hRS7-SN-38 at nontoxic doses in mice bearing Calu-3 (P ≤ 0.05), Capan-1 (P < 0.018), BxPC-3 (P < 0.005), and COLO 205 tumors (P < 0.033) when compared to nontargeting control ADCs. Mice tolerated a dose of 2 × 12 mg/kg (SN-38 equivalents) with only short-lived elevations in ALT and AST liver enzyme levels. Cynomolgus monkeys infused with 2 × 0.96 mg/kg exhibited only transient decreases in blood counts, although, importantly, the values did not fall below normal ranges. Conclusions: The anti-Trop-2 hRS7-CL2A-SN-38 ADC provides significant and specific antitumor effects against a range of human solid tumor types. It is well tolerated in monkeys, with tissue Trop-2 expression similar to humans, at clinically relevant doses, and warrants clinical investigation.[1] |
Solubility Data
| Solubility (In Vitro) | DMSO : ~100 mg/mL (~67.54 mM） |
| Solubility (In Vivo) |
Solubility in Formulation 1: 2.08 mg/mL (1.40 mM) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.08 mg/mL (1.40 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. 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. Solubility in Formulation 3: ≥ 2.08 mg/mL (1.40 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly. Solubility in Formulation 4: 10% DMSO+ 40% PEG300+ 5% Tween-80+ 45% saline: 2.08 mg/mL (1.40 mM) (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 0.5752 mL | 2.8760 mL | 5.7521 mL | |
| 5 mM | 0.1150 mL | 0.5752 mL | 1.1504 mL | |
| 10 mM | 0.0575 mL | 0.2876 mL | 0.5752 mL |