Camptothecins/DNA Topoisomerase I
CL2A-SN-38 is a derivative of SN-38, which is the active metabolite of the prodrug irinotecan (CPT-11). SN-38 functions as a topoisomerase I inhibitor. [1]

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].
In vitro cytotoxicity studies demonstrated that hRS7-CL2A-SN-38 had IC50 values in the nM range against several different solid tumor lines (Table 1). The IC50 with free SN-38 was lower than the conjugate in all cell lines. While there was no correlation between Trop-2 expression and sensitivity to hRS7-CL2A-SN-38, the IC50 ratio of the ADC vs. free SN-38 was lower in the higher Trop-2-expressing cells, most likely reflecting the enhanced ability to internalize the drug when more antigen is present.
SN-38 is known to activate several signaling pathways in cells, leading to apoptosis (34–37). Our initial studies examined the expression of two proteins involved in early signaling events (p21Waf1/Cip1 and p53) and one late apoptotic event (cleavage of poly-ADP-ribose polymerase (PARP)) in vitro (Fig. 2). In BxPC-3 (Fig. 2A), SN-38 led to a 20-fold increase in p21Waf1/Cip1 expression, while hRS7-CL2A-SN-38 resulted in only a 10-fold increase, a finding consistent with the higher activity with free SN-38 in this cell line (Table 1). However, hRS7-CL2A-SN-38 increased p21Waf1/Cip1 expression in Calu-3 more than 2-fold over free SN-38 (Fig. 2B).
A greater disparity between hRS7-CL2A-SN-38- and free SN-38-mediated signaling events was observed in p53 expression. In both BxPC-3 and Calu-3, up-regulation of p53 with free SN-38 was not evident until 48 h, while hRS7-CL2A-SN-38 up-regulated p53 within 24 h. Additionally, p53 expression in cells exposed to the ADC was higher in both cell lines compared to SN-38. Interestingly, while hRS7 IgG had no appreciable effect on p21Waf1/Cip1 expression, it did induce the up-regulation of p53 in both BxPC-3 and Calu-3, but only after a 48-h exposure. In terms of later apoptotic events, cleavage of PARP was evident in both cell lines when incubated with either SN-38 or the conjugate (Fig. 2C). The presence of the cleaved PARP was higher at 24 h in BxPC-3, which correlates with high expression of p21 and its lower IC50. The higher degree of cleavage with free SN-38 over the ADC was consistent with the cytotoxicity findings [1].

---

The CL2A-SN-38 derivative was conjugated to the anti-Trop-2 antibody hRS7 to form the antibody-drug conjugate (ADC) hRS7-CL2A-SN-38. This conjugate demonstrated cytotoxic activity against multiple human solid tumor cell lines expressing Trop-2. [1]
The in vitro serum stability half-life (t1/2) of the hRS7-CL2A-SN-38 conjugate was approximately 20 hours. [1]
The binding affinity (Kd) of the hRS7-CL2A-SN-38 conjugate for the Trop-2 antigen was approximately 1.2 nM. [1]
The average drug substitution ratio for the hRS7-CL2A-SN-38 conjugate was approximately 6 molecules of SN-38 per antibody molecule (IgG). [1]

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].

---

Efficacy of hRS7-SN-38 [1]
Since Trop-2 is widely expressed in several human carcinomas, studies were performed in several different human cancer models, which started with an evaluation of the hRS7-CL2-SN-38 linkage, but later, conjugates with the CL2A-linkage were used. Calu-3-bearing nude mice given 0.04 mg SN-38/kg of the hRS7-CL2-SN-38 every 4 days x 4 had a significantly improved response compared to animals administered the equivalent amount of hLL2-CL2-SN-38 (TV=0.14 ± 0.22 cm3 vs. 0.80 ± 0.91 cm3, respectively; AUC42days P<0.026) (Fig. 3A). A dose-response was observed when the dose was increased to 0.4 mg/kg SN-38. At this higher dose level, all mice given the specific hRS7 conjugate were ‘cured’ within 28 days, and remained tumor-free until the end of the study on day 147, while tumors re-grew in animals treated with the irrelevant ADC (specific vs. irrelevant AUC98days: P=0.05). In mice receiving the mixture of hRS7 IgG and SN-38, tumors progressed >4.5-fold by day 56 (TV=1.10 ± 0.88 cm3; AUC56days P<0.006 versus hRS7-CL2-SN-38).
Efficacy also was examined in human colonic (COLO 205) and pancreatic (Capan-1) tumor xenografts. In COLO 205 tumor-bearing animals, (Fig. 3B), hRS7-CL2-SN-38 (0.4 mg/kg, q4dx8) prevented tumor growth over the 28-day treatment period with significantly smaller tumors compared to control anti-CD20 ADC (hA20-CL2-SN-38), or hRS7 IgG (TV=0.16 ± 0.09 cm3, 1.19 ± 0.59 cm3, and 1.77 ± 0.93 cm3, respectively; AUC28days P<0.016). The MTD of irinotecan (24 mg SN-38/kg, q2dx5) was as effective as hRS7-CL2-SN-38, since mouse serum can more efficiently convert irinotecan to SN-38 (38–41) than human serum, but the SN-38 dose in irinotecan (2400 μg cumulative) was 37.5-fold greater than with the conjugate (64 μg total). Animals bearing Capan-1 showed no significant response to irinotecan alone when given at an SN-38-dose equivalent to the hRS7-CL2-SN-38 conjugate (e.g., on day 35, average tumor size was 0.04 ± 0.05 cm3 in animals given 0.4 mg SN-38/kg hRS7-SN-38 vs. 1.78 ± 0.62 cm3 in irinotecan-treated animals given 0.4 mg/kg SN-38; AUCday35 P<0.001) (Fig. 3C). When the irinotecan dose was increased 10-fold to 4 mg/kg SN-38, the response improved, but still was not as significant as the conjugate at the 0.4 mg/kg SN-38 dose level (TV=0.17 ± 0.18 cm3 vs. 1.69 ± 0.47 cm3, AUCday49 P<0.001). An equal dose of non-targeting hA20-CL2-SN-38 also had a significant anti-tumor effect as compared to irinotecan-treated animals, but the specific hRS7 conjugate was significantly better than the irrelevant ADC (TV=0.17 ± 0.18 cm3 vs. 0.80 ± 0.68 cm3, AUCday49 P<0.018).
Studies with the hRS7-CL2A-SN-38 ADC were then extended to two other models of human epithelial cancers. In mice bearing BxPC-3 human pancreatic tumors (Fig. 3D), hRS7-CL2A-SN-38 again significantly inhibited tumor growth in comparison to control mice treated with saline or an equivalent amount of non-targeting hA20-CL2A-SN-38 (TV=0.24 ± 0.11 cm3 vs. 1.17 ± 0.45 cm3 and 1.05 ± 0.73 cm3, respectively; AUCday21 P<0.001), or irinotecan given at a 10-fold higher SN-38 equivalent dose (TV=0.27 ± 0.18 cm3 vs. 0.90 ± 0.62 cm3, respectively; AUCday25 P<0.004). Interestingly, in mice bearing SK-MES-1 human squamous cell lung tumors treated with 0.4 mg/kg of the ADC (Fig. 3E), tumor growth inhibition was superior to saline or unconjugated hRS7 IgG (TV=0.36 ± 0.25 cm3 vs. 1.02 ± 0.70 cm3 and 1.30 ± 1.08 cm3, respectively; AUC28 days, P<0.043), but non-targeting hA20-CL2A-SN-38 or the MTD of irinotecan provided the same anti-tumor effects as the specific hRS7-SN-38 conjugate.

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].

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].

---

Cytotoxicity Assay (ADC): The cytotoxic activity of the ADC (hRS7-CL2A-SN-38) was evaluated in vitro against various human cancer cell lines (e.g., Calu-3, COLO 205, Capan-1, PC-3, SK-MES-1, BxPC-3). The half-maximal inhibitory concentration (IC50) values for the ADC were in the nanomolar (nM) range for all tested cell lines. For example, the IC50 was 9.97 nM for Calu-3, 1.95 nM for COLO 205, 6.99 nM for Capan-1, 4.24 nM for PC-3, 23.14 nM for SK-MES-1, and 4.03 nM for BxPC-3 cells. These values are reported as SN-38 equivalents. The IC50 of free SN-38 was lower than that of the ADC in all cell lines. [1]
Mechanism of Action Study (ADC): To investigate signaling pathways, BxPC-3 and Calu-3 cells were plated overnight in 6-well plates. Cells were then treated with the ADC hRS7-CL2A-SN-38 (at 1 µM SN-38 equivalents), free SN-38 (1 µM), or the naked hRS7 antibody (25 µg/mL) for specified time points (e.g., 24, 48 hours). After treatment, cells were lysed. Proteins (20 µg per sample) from the lysates were separated by SDS-PAGE (4-20% gradient gels) and transferred to membranes for Western blot analysis. Membranes were probed with specific primary antibodies against p21Waf1/Cip1, p53, poly(ADP-ribose) polymerase (PARP), and β-actin (loading control). Protein expression levels were visualized and quantified relative to untreated control cells and normalized to β-actin. The study showed that the ADC induced up-regulation of p21 and p53, and cleavage of PARP, indicating activation of apoptotic pathways. Notably, the ADC induced p53 up-regulation earlier (within 24 hours) compared to free SN-38 in some cell lines. [1]

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.

Biodistribution of hRS7-CL2A-SN-38 [1]
In mice carrying SK-MES-1 human squamous cell lung cancer xenografts (Supplementary Table S1), the biodistribution of hRS7-CL2A-SN-38 or unconjugated hRS7 IgG was compared using the corresponding 111In-labeled substrate. Pharmacokinetic analysis was performed to determine the clearance rate of hRS7-CL2A-SN-38 relative to unconjugated hRS7 (Fig. 4A). The ADC was cleared faster than an equivalent amount of unconjugated hRS7, with a half-life and mean residence time of approximately 40% shorter. Nevertheless, this had little effect on tumor uptake (Fig. 4B). Although there were significant differences at 24 and 48 hours, the levels of the two drugs in tumors were similar by 72 hours (peak uptake). In normal tissues, the differences were most significant in the liver (Fig. 4C) and spleen (Fig. 4D). Twenty-four hours post-injection, the level of hRS7-CL2A-SN-38 in the liver was more than twice that of hRS7 IgG. Conversely, in the spleen, the peak uptake level (48-hour time point) of parental hRS7 IgG was three times that of hRS7-CL2A-SN-38. Uptake and clearance in other tissues generally reflected differences in blood concentrations. Because the treatment was administered twice weekly, we examined tumor uptake in a cohort of animals. These animals received a pre-dose of 0.2 mg/kg (250 μg protein) of hRS7 ADC three days prior to injection of the ¹¹¹In-labeled antibody. Compared with unpre-administered mice, tumor uptake of In-hRS7-CL2A-SN-38 was significantly reduced in pre-administered mice at every time point (e.g., at 72 hours, tumor uptake in the pre-administered group was 12.5 ± 3.8% ID/g, compared to 25.4 ± 8.1% ID/g in the unpre-administered group; P = 0.0123; Figure 4E). Pre-administration had no significant effect on blood clearance or tissue uptake (Supplementary Table S2). These studies suggest that prior administration can reduce the accumulation of specific antibodies in tumors in certain tumor models, which may explain why the specificity of the treatment response decreases with increasing antibody-drug conjugate (ADC) doses and why further dose increases are not recommended. Distribution and Clearance (ADC): Biodistribution and pharmacokinetic studies were conducted in nude mice with subcutaneously transplanted SK-MES-1 tumors using a radiolabeled ADC, In-DTPA-hRS7-CL2A-SN-38. Mice were intravenously injected with 20 µCi (250 µg protein) of the radiolabeled ADC. Mice were sacrificed at different time points after injection. Blood, tumors, and various tissues (e.g., liver, spleen) were collected, weighed, and their radioactivity was measured by gamma scintillation counting to determine the percentage of the injected dose per gram of tissue (%ID/g). Pharmacokinetic parameters of blood clearance were analyzed using dedicated software. The study found that the ADC was cleared from the blood more rapidly and had approximately twice the liver uptake compared to the unconjugated hRS7 antibody, attributed to the hydrophobicity of the SN-38 payload. Tumor uptake of the ADC was similar to that of the naked antibody. Tumor uptake decreased after three days of pretreatment with the unlabeled ADC, suggesting antigen saturation. [1]

Tolerance to hRS7-CL2A-SN-38 in Swiss Webster mice and cynomolgus monkeys [1]
Swiss Webster mice tolerated two doses of hRS7-CL2A-SN-38 over three days at doses of 4, 8, and 12 mg/kg, with only a slight, transient decrease in body weight (Supplementary Figure S2). No hematopoietic toxicity occurred, and serum biochemistry showed only elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels (Figure 5). After 7 days of treatment, AST levels in all three treatment groups were elevated above normal (>298 U/L) (Figure 5A), with the highest proportion of mice in the 2 × 8 mg/kg group. However, by day 15 after treatment, AST levels in most animals returned to normal. ALT levels were also elevated above normal (>77 U/L) during the first 7 days of treatment (Figure 5B) and returned to normal by day 15. No histological evidence of tissue damage was shown in the livers of any of these mice (not shown). Regarding renal function, only the treatment groups showed slight increases in glucose and chloride levels. In the 2 × 8 mg/kg dose group, 5 out of 7 mice showed mild increases in glucose levels (range 273 to 320 mg/dL, upper limit of normal 263 mg/dL), which returned to normal 15 days post-injection. Similarly, in the two highest dose groups, chloride levels were also slightly elevated, ranging from 116 to 127 mmol/L (upper limit of normal 115 mmol/L) (57% in the 2 × 8 mg/kg group and 100% in the 2 × 12 mg/kg group), and remained elevated for 15 days post-injection. This may also indicate gastrointestinal toxicity, as most chloride is acquired through intestinal absorption; however, no histological evidence of tissue damage was found in any organ system examined at the end of the experiment (not shown). Since mice do not express Trop-2, a more suitable model is needed to determine the potential of the hRS7 conjugate for clinical applications. Immunohistochemical studies showed binding in various tissues of both humans and cynomolgus monkeys (mammary gland, eye, gastrointestinal tract, kidney, lung, ovary, fallopian tube, pancreas, parathyroid gland, prostate, salivary gland, skin, thymus, thyroid gland, tonsils, ureter, bladder, and uterus) (not shown). Based on this cross-reactivity, we conducted a tolerability study in monkeys. The hRS7-CL2A-SN-38 group receiving 2 × 0.96 mg/kg SN-38 did not experience significant clinical events after infusion or before the end of the study. Body weight loss did not exceed 7.3%, and the body returned to adaptation weight by day 15. Most hematologic cell counts (neutrophil and platelet counts are shown in Figures 5C and 5D) showed transient decreases, but the values did not fall below the normal range. Serum biochemical parameters were normal. Histopathological examination of the animals at day 11 (8 days after the last injection) revealed microscopic changes in hematopoietic organs (thymus, submandibular and mesenteric lymph nodes, spleen, and bone marrow), gastrointestinal organs (stomach, duodenum, jejunum, ileum, cecum, colon, and rectum), female reproductive organs (ovaries, uterus, and vagina), and injection sites. These changes ranged in severity from mild to moderate. By the end of the recovery period (day 32), all tissues except the thymus and gastrointestinal tract had fully recovered, with the thymus and gastrointestinal tract also tending towards complete recovery at later time points. In the conjugate group at the 2 × 1.92 mg SN-38/kg dose, one death occurred due to gastrointestinal complications and bone marrow suppression; other animals in this group also experienced similar but more severe side effects than those in the 2 × 0.96 mg/kg group. These data indicate that the dose-limiting toxicities are similar to those of irinotecan, namely gastrointestinal and hematologic toxicities. Therefore, the maximum tolerated dose (MTD) of hRS7-CL2A-SN-38 is 2 × 0.96 to 1.92 mg SN-38/kg, equivalent to a human equivalent dose of 2 × 0.3 to 0.6 mg/kg SN-38.

---

Mouse toxicity (ADC): The tolerability of the ADC (hRS7-CL2A-SN-38) was evaluated in Swiss-Webster mice. Mice received two intraperitoneal injections three days apart, each at an equivalent dose of 4, 8, or 12 mg/kg SN-38 (equivalent to 250, 500, or 750 mg conjugate protein/kg per injection). Control mice were injected with buffer. Blood and serum were collected and analyzed on days 7 and 15 after the last injection. A transient increase in liver enzymes (AST and ALT) above the normal range was observed within 7 days after treatment, returning to normal on day 15. No histological evidence of liver tissue damage was found. Mild and transient increases in blood glucose and chloride levels were also observed in some high-dose groups. No significant hematologic toxicity was observed in mice. [1] Monkey toxicity (antibody-drug conjugate): A dose-escalation tolerance study was conducted in cynomolgus monkeys (whose tissues express Trop-2 similar to that in humans). Monkeys received two intravenous infusions of the antibody-drug conjugate (hRS7-CL2A-SN-38) three days apart, at equivalent doses of 0.96 mg/kg/dose or 1.92 mg/kg/dose. Clinical observations, body weight, hematologic, serologic and histopathologic parameters were evaluated. At the lower doses (2 x 0.96 mg/kg SN-38 equivalent), only mild and reversible toxicity was observed in monkeys. Transient decreases in blood cell counts (neutrophils, platelets) were observed, but the values were not below the normal range. No significant abnormalities were observed in serum biochemistry. Histopathological examination on day 11 (8 days after the last administration) showed mild to moderate changes in hematopoietic organs, gastrointestinal tract, and female reproductive organs, with most tissues fully recovered by the end of the recovery period (day 32). At higher doses (2 x 1.92 mg/kg SN-38 equivalent), one monkey died from gastrointestinal complications and bone marrow suppression, and other animals experienced more severe adverse reactions. Dose-limiting toxicities (gastrointestinal and hematologic toxicities) were the same as irinotecan. The maximum tolerated dose (MTD) in monkeys was estimated to be between 2 × 0.96 mg/kg and 2 × 1.92 mg/kg SN-38 equivalent. [1]

[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.

Objective: To evaluate the efficacy of SN-38-anti-Trop-2 antibody-drug conjugates (ADCs) against various human solid tumors and to assess their tolerability in mice and monkeys, where tissue cross-reactivity to hRS7 in monkeys is similar to that in humans. Experimental Design: Two SN-38 Derivative, CL2-SN-38 and CL2A-SN-38, were conjugated to the humanized anti-Trop-2 antibody hRS7. The stability, binding affinity, and cytotoxicity of the immunoconjugates were characterized in vitro. Efficacy was tested in five human solid tumor xenograft models expressing the Trop-2 antigen. Toxicity was assessed in mice and cynomolgus monkeys. Results: The hRS7 conjugates of the two SN-38 Derivative were comparable in terms of drug replacement rate (~6), cell binding affinity (K_d ~ 1.2 nmol/L), cytotoxicity (IC₅₀ ~ 2.2 nmol/L), and in vitro serum stability (t_1/2 ~ 20 h). Following cell exposure to the antibody-drug conjugate (ADC), the PARP cleavage signaling pathway was detected, but the upregulation of p53 and p21 expression differed significantly compared to free SN-38. In tumor-bearing mice, hRS7-SN-38, at a non-toxic dose, exhibited significant antitumor activity against Calu-3 (P ≤ 0.05), Capan-1 (P < 0.018), BxPC-3 (P < 0.005), and COLO 205 (P < 0.033) tumors, with statistically significant differences compared to the non-targeted control ADC. Mice tolerated a dose of 2 × 12 mg/kg (SN-38 equivalent) with only transient increases in ALT and AST liver enzyme levels. In cynomolgus monkeys, an infusion of 2 × 0.96 mg/kg resulted in only a transient decrease in blood cell counts; importantly, these values did not fall below the normal range. Conclusion: The anti-Trop-2 antibody-drug conjugate hRS7-CL2A-SN-38 exhibits significant and specific antitumor activity against a variety of human solid tumors. The compound is well tolerated in monkeys, and at clinically relevant doses, the expression of Trop-2 in its tissues is similar to that in humans, warranting further clinical investigation. [1]

---

CL2A-SN-38 is a modified derivative of the topoisomerase I inhibitor SN-38, designed to conjugate an antibody-drug conjugate (ADC) by coupling it with an antibody via a cleavable linker. [1]
Its structure is related to the earlier derivative CL2-SN-38, but the phenylalanine moiety was removed from the linker region to simplify synthesis. This modification did not adversely affect the conjugation efficiency, stability, binding affinity, or in vivo potency of the resulting ADC compared to the CL2 version. [1]
The molecular weight of the CL2A-SN-38 derivative is reported to be 1480 g/mol. [1]
When conjugated with the anti-Trop-2 antibody hRS7, the resulting antibody-drug conjugate (ADC) (hRS7-CL2A-SN-38) exhibited significant and specific antitumor efficacy at non-toxic doses in various human tumor xenograft mouse models (including lung cancer, pancreatic cancer, and colorectal cancer). [1]
The ADC was designed to release SN-38 into target cells via pH-sensitive hydrolysis of the benzyl carbonate bond in an acidic lysosomal environment, rather than via cathepsin B cleavage, after internalization and linker cleavage in the target cells. [1]

C77H101CL4N11O26

1738.4960

1479.68

C, 53.20; H, 5.86; Cl, 8.16; N, 8.86; O, 23.93

1279680-68-0

1279680-68-0

89983570

Light yellow to yellow solid powder

-0.1

6

26

50

106

2930

2

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

WWSNNYDLXHTRLZ-JGQYWRMXSA-N

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

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)

CL2A-SN-38; CL2A-SN 38; CL2A-SN38; CL2ASN-38; CL2A SN 38; CL2ASN38; CL2A-SN38 DCA salt; CL2A-SN38 dichloroacetic acid.

2934.99.9001

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.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~100 mg/mL (~67.54 mM）

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.

---

View More

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.)