Exherin free base (ADH-1) is a cyclic pentapeptide that disrupts N-cadherin interactions. It targets N-cadherin expressed on both tumor cells and tumor endothelium. The study does not provide IC₅₀, Ki, or EC₅₀ values for binding to N-cadherin. [3]

ADH-1 (0.2 mg/mL) is a potent inhibitor of N-cadherin-induced cell motility and inhibits collagen I-mediated alterations in pancreatic cancer cells. ADH-1 causes apoptosis in a way that is both dose-dependent and N-cadherin-dependent at 0, 0.1, 0.2, 0.5, and 1.0 mg/mL [1].

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Exherin was evaluated in vitro for its effects on endothelial cell permeability and on melanoma cell signaling.

1. Endothelial Cell Permeability Assay: In HUVEC endothelial cells expressing N-cadherin, pretreatment with Exherin (1 mg/mL) for 1 hour resulted in an approximate two-fold increase in permeability to 40 kDa FITC-conjugated dextran compared to saline controls. This effect was observed both in the presence and absence of serum and growth factors, and even exceeded the permeability increase induced by VEGF (10 ng/mL), which was used as a positive control. [3]
2. N-cadherin Gene Expression: Real-time quantitative RT-PCR was used to measure N-cadherin gene transcripts in HUVEC cells. Expression was normalized to GAPDH and reported relative to the high N-cadherin expressing melanoma cell line DM366. [3]
3. Cell Signaling (Western Blot): In exponentially growing A375 (high N-cadherin, PTEN-expressing) and DM443 (low N-cadherin, PTEN-null) melanoma cells treated with Exherin (0-1 mg/mL) for 1 hour, Exherin increased AKT phosphorylation (at serine 473) in A375 cells but not in DM443 cells. [3]

ADH-1 (50 mg/kg) bluntly suppresses tumor development and metastasis in a pancreatic cancer mice model. ADH-1 inhibited tumor cell invasion and metastasis in an orthotopic model of pancreatic cancer employing BxPC-3 cells overexpressing N-cadherin [1]. ADH-1 did not exhibit anti-angiogenic activity in the rat aortic ring assay at the levels examined, nor did it have any anti-tumor potential in the PC3 subcutaneous xenograft tumor model [2]. When ADH-1 was administered to xenografts A375 but not DM443 xenografts, AKT serine 473 was phosphorylated more. N-cadherin expression is marginally downregulated by ADH-1 in both xenografts [3].

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Exherin demonstrates dichotomous effects on melanoma tumor growth in xenograft models, depending on the cell line and chemotherapeutic agent used. It also consistently increases vascular permeability.

1. Effect on Tumor Growth (without Chemotherapy): In rats bearing DM443 xenografts (low N-cadherin), systemic Exherin (100 mg/kg, i.p.) followed by saline infusion did not significantly alter tumor growth rate (0.10 ± 0.04 d⁻¹ vs. 0.20 ± 0.04 d⁻¹ for controls, p=0.26). In contrast, for A375 xenografts (high N-cadherin), the same treatment dramatically and significantly increased tumor growth rate by nearly 2-fold (0.53 ± 0.07 d⁻¹ vs. 0.27 ± 0.02 d⁻¹, p=0.018). [3]
2. Combination with Regional Melphalan (LPAM-ILI): For DM443 xenografts, combination therapy with systemic Exherin and regional LPAM infusion significantly decreased tumor growth rate by 75% compared to LPAM alone (0.03 ± 0.01 d⁻¹ vs. 0.12 ± 0.01 d⁻¹, p<0.001). For A375 xenografts, combination therapy completely counteracted the growth-augmenting effect of Exherin alone, decreasing growth rate by 99% compared to controls. Complete tumor response was observed in 80% (4/5) of animals treated with the combination vs. 33% (2/6) treated with LPAM alone. [3]
3. Combination with Regional Temozolomide (TMZ-ILI): For DM443 xenografts, combination therapy with systemic Exherin and regional TMZ infusion led to a 33% reduction in tumor growth rate over TMZ alone (0.08 ± 0.01 d⁻¹ vs. 0.12 ± 0.02 d⁻¹, p=0.012). For A375 xenografts, Exherin failed to improve TMZ efficacy and could not overcome the growth-augmenting effect seen with Exherin alone. The combination therapy resulted in a tumor growth rate closer to that of Exherin alone. [3]
4. Effect on Vascular Permeability (Evans Blue Dye Assay): One hour after systemic Exherin (100 mg/kg, i.p.) administration, Evans blue dye extravasation into tumors during ILI increased significantly by 28.4% in DM443 xenografts (p=0.0001) and 32.8% in A375 xenografts (p=0.0001) compared to saline controls. [3]
5. Effect on Interstitial Fluid Pressure (IFP): One hour after systemic Exherin (100 mg/kg, i.p.) administration, tumor interstitial fluid pressure was not significantly altered in either DM443 or A375 xenografts. [3]
6. Effect on Drug Delivery: Immunohistochemical staining showed that systemic Exherin pretreatment resulted in an approximate 12-fold and 16-fold increase in LPAM-DNA adduct formation (a surrogate for LPAM delivery) in DM443 and A375 xenografts, respectively. In contrast, Exherin pretreatment did not increase DNA damage (p-H2A.x staining, a surrogate for TMZ delivery) following TMZ-ILI. [3]
7. Effect on Cell Signaling (in vivo): Western blot analysis of tumor samples confirmed that Exherin treatment increased AKT phosphorylation at serine 473 in A375 xenografts but not in DM443 xenografts. Reverse Phase Protein Array (RPPA) analysis revealed that in DM443 xenografts, Exherin inhibited the PI3K-AKT-mTOR pathway. In A375 xenografts, it increased expression of multiple phospho-proteins in this pathway and decreased expression of PTEN. Exherin inhibited activation-specific markers in other pro-survival pathways (e.g., EGFR, STAT3, MEK) in both xenografts. [3]

No direct enzyme activity assays were performed. Key assays were cell-based functional assays (permeability) and protein analysis (Western blot, RPPA).

1. Endothelial Cell Permeability Assay: HUVECs were grown to confluence on fibronectin-coated transwell inserts. Diffusion of 40 kDa FITC-dextran across the monolayer was measured 30 minutes after addition, following a 1-hour treatment with Exherin (1 mg/mL), VEGF (10 ng/mL), or saline, in the presence or absence of serum and growth factors. Fluorescence in the lower compartment was measured with a microplate reader. [3]
2. Real-time quantitative RT-PCR: Total RNA was extracted from cells, and cDNA was synthesized. N-cadherin gene transcripts were amplified using SYBR-Green qPCR with specific primers. CT values were normalized to GAPDH expression. [3]
3. Reverse Phase Protein Array (RPPA): Proteins isolated from xenografts were analyzed by the MD Anderson Cancer Center Functional Proteomics Core Facility. Relative protein expression levels were compared between Exherin- and saline-treated tumors. Log₂ values were converted to linear values to determine differences in expression. [3]

Two main cell-based assays were used: an endothelial permeability assay and cell signaling studies.

1. Endothelial Cell Permeability Assay: HUVEC cells were cultured in F-12K medium supplemented with heparin, endothelial cell growth supplement, and FBS. Cells were grown to confluence on fibronectin-coated transwell inserts. Permeability was assessed by measuring the diffusion of 40 kDa FITC-dextran across the monolayer after treatment with Exherin, VEGF, or saline. [3]
2. Cell Signaling Studies (Western Blot): DM443 and A375 melanoma cells were cultured in Isocove's modified Dulbecco's medium with 10% FBS, glutamine, and antibiotics. Exponentially growing cells were serum-starved overnight and then treated with Exherin (0-1 mg/mL) for 1 hour. Cell lysates were analyzed by Western blot for AKT phosphorylation and PTEN expression. [3]

A detailed xenograft model was used to evaluate the in vivo effects of Exherin.

1. **Xenograft Model:** DM443 and A375 melanoma cells were injected into the hind limbs of nude rats. Tumors were grown to approximately 1 cm in diameter or 2 cm³ in volume. [3]
2. **Drug Preparation and Administration:** Exherin was prepared in PBS and administered via intraperitoneal (i.p.) injection at a dose of 100 mg/kg body weight (10 mL/kg). It was given 1 hour prior to isolated limb infusion (ILI) or, in growth studies, as a single dose or as part of a multi-dose regimen. [3]
3. **Isolated Limb Infusion (ILI):** ILI was performed with melphalan (LPAM) or temozolomide (TMZ). The infusate was prepared at a concentration to deliver 90 mg/kg LPAM or 2000 mg/kg TMZ in a volume of 22.5 mL. Infusions were performed 1 hour after systemic Exherin or saline administration. [3]
4. **Evans Blue Dye Assay:** One hour after systemic Exherin (100 mg/kg, i.p.), ILI was performed using Evan's blue dye solution (50 mg/kg in saline) infused at 1.5 mL/min for 15 minutes, followed by a 2-minute saline washout. Tumors were excised, incubated in formamide for 72 hours at 37°C, and the absorbance of the extracted dye was measured at 595 nm and normalized to tumor volume. [3]
5. **Interstitial Fluid Pressure (IFP) Measurement:** One hour after systemic Exherin (100 mg/kg, i.p.), tumor IFP was measured with a needle probe pressure monitor fitted with an 18-gauge side-ported needle. The needle was inserted into the center of the tumor, and IFP was recorded in mmHg once stabilized. [3]
6. **Tissue Collection for Analysis:** Animals were euthanized at various time points (e.g., 24 hours post-ILI for IHC, 1 hour post-Exherin for RPPA). Tumors were excised, fixed in formalin for IHC or flash-frozen for protein analysis. [3]

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A detailed xenograft model was used to evaluate the in vivo effects of Exherin.

1. Xenograft Model: DM443 and A375 melanoma cells were injected into the hind limbs of nude rats. Tumors were grown to approximately 1 cm in diameter or 2 cm³ in volume. [3]
2. Drug Preparation and Administration: Exherin was prepared in PBS and administered via intraperitoneal (i.p.) injection at a dose of 100 mg/kg body weight (10 mL/kg). It was given 1 hour prior to isolated limb infusion (ILI) or, in growth studies, as a single dose or as part of a multi-dose regimen. [3]
3. Isolated Limb Infusion (ILI): ILI was performed with melphalan (LPAM) or temozolomide (TMZ). The infusate was prepared at a concentration to deliver 90 mg/kg LPAM or 2000 mg/kg TMZ in a volume of 22.5 mL. Infusions were performed 1 hour after systemic Exherin or saline administration. [3]
4. Evans Blue Dye Assay: One hour after systemic Exherin (100 mg/kg, i.p.), ILI was performed using Evan's blue dye solution (50 mg/kg in saline) infused at 1.5 mL/min for 15 minutes, followed by a 2-minute saline washout. Tumors were excised, incubated in formamide for 72 hours at 37°C, and the absorbance of the extracted dye was measured at 595 nm and normalized to tumor volume. [3]
5. Interstitial Fluid Pressure (IFP) Measurement: One hour after systemic Exherin (100 mg/kg, i.p.), tumor IFP was measured with a needle probe pressure monitor fitted with an 18-gauge side-ported needle. The needle was inserted into the center of the tumor, and IFP was recorded in mmHg once stabilized. [3]
6. Tissue Collection for Analysis: Animals were euthanized at various time points (e.g., 24 hours post-ILI for IHC, 1 hour post-Exherin for RPPA). Tumors were excised, fixed in formalin for IHC or flash-frozen for protein analysis. [3]

Protein Binding
ADH-1 binds to N-cadherin and inhibits its activity.

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[1]. ADH-1 suppresses N-cadherin-dependent pancreatic cancer progression. Int J Cancer. 2008 Jan 1;122(1):71-7.

[2]. ADH1, an N-cadherin inhibitor, evaluated in preclinical models of angiogenesis and androgen-independent prostate cancer. Anticancer Drugs. 2007 Jun;18(5):563-8.

[3]. Targeting N-cadherin increases vascular permeability and differentially activates AKT in melanoma. Ann Surg. 2015 Feb;261(2):368-77.

Adherex's biotechnology compound ADH-1 targets N-cadherin, a protein found on certain tumor cells and established tumor blood vessels. ADH-1 is currently in clinical development for use in combination with a range of chemotherapy drugs to investigate the synergistic effects observed in preclinical models. In late 2006, the company also completed patient recruitment for Phase Ib/II and Phase II clinical trials of ADH-1 as a monotherapy. Cadherins are molecules involved in cell adhesion and cell signaling, crucial for the development of tissues, organs, and organisms. Drugs that target and inhibit cadherin function have the potential to inhibit cancer progression in two distinct ways: Directly targeting cadherins expressed on cancer cells may interfere with cadherin-mediated signaling, leading to cancer cell apoptosis (death). Cadherin inhibitors may exploit inherent structural defects in tumor blood vessels, leading to angiogenesis (vascular rupture) and tumor damage. With the increasing invasiveness, aggressiveness, and malignancy of many tumors, researchers have found a significant increase in N-cadherin expression, making it an important target for developing anticancer therapies. Poorly differentiated, highly invasive cancers are characterized by the overexpression of N-cadherin (rather than E-cadherin). This alteration in primary cadherin expression causes epithelial cells to lose their tight adhesion, polarity, and clear morphology, becoming loosely adherent, flattened, and easily migrating. This cadherin shift promotes dedifferentiation, local invasion, and metastasis, ultimately leading to a poor prognosis. Since N-cadherin is overexpressed in a variety of tumors, ADH-1 may have potential applications in the treatment of various cancers. As tumors progress, with increasing grade, invasiveness, and metastasis, the expression frequency of N-cadherin typically increases. ADH-1 is a small cyclic pentapeptide angiogenesis target with potential antitumor and anti-angiogenic activities. ADH-1 selectively and competitively binds to and blocks N-cadherin, which may lead to tumor angiogenesis disruption, inhibition of tumor cell growth, and induction of apoptosis in tumor cells and endothelial cells. N-cadherin is a transmembrane glycoprotein on the cell surface, belonging to the cadherin superfamily, and participates in calcium-mediated intercellular adhesion and signal transduction mechanisms. ADH-1 may be upregulated in the endothelial cells and pericytes of certain invasive tumors and tumor blood vessels.

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Drug Indications
It has been studied for the treatment of breast cancer, other cancers/tumors (unspecified), melanoma, ovarian cancer, and solid tumors.

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Mechanism of Action
Although ADH-1 has only one molecular target, N-cadherin, we believe its anticancer effect stems from two distinct mechanisms of action—apoptosis and tumor angiogenesis. N-cadherin appears to be a tumor cell survival factor. Cell culture studies have shown that inhibiting the binding of N-cadherin between tumor cells leads to tumor cell apoptosis, which we believe is due to the disruption of cadherin-regulated cell survival signaling. ADH-1 also appears to disrupt the blood vessels required for cancerous tumor growth and proliferation; we have observed bleeding in both clinical and preclinical studies. We believe the mechanism of this disruption is either competitive inhibition of cadherin binding between endothelial cells in the tumor vessel wall or apoptosis of tumor cells that form part of the vessel wall; both lead to vascular leakage and rupture. The latter involves the tumor \"chimera\" phenomenon, where tumor cells (along with endothelial cells) form part of the vessel wall. Inducing the death of these tumor cells leads to tumor vessel destruction.

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Pharmacodynamics
ADH-1 is a biotechnology compound that targets N-cadherin, a protein present on certain tumor cells and established tumor blood vessels. Cadherin is a cell adhesion and cell signaling molecule, crucial for the development of tissues, organs, and organisms. Drugs that target and inhibit cadherin function hold promise for blocking cancer progression at two distinct levels: Directly targeting cadherin expressed on the surface of cancer cells may interfere with cadherin-mediated signaling, leading to cancer cell apoptosis (death). Cadherin inhibitors may exploit inherent structural defects in tumor blood vessels, causing angiogenesis (vessel rupture) and tumor damage. This compound is suitable for the treatment of a variety of aggressive cancers, and ADH-1 has been shown to have a synergistic effect with taxane chemotherapy drugs in the systemic treatment of ovarian cancer xenografts.

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Exherin free base (ADH-1) is a cyclic pentapeptide that disrupts N-cadherin-mediated interactions. N-cadherin is upregulated in several malignancies, including melanoma, and is involved in tumor cell adhesion, survival, and angiogenesis. This study investigates the dual effects of Exherin in the context of regional chemotherapy for melanoma. It reveals that Exherin can have opposing effects on tumor growth depending on the tumor's molecular characteristics (e.g., PTEN status, N-cadherin expression). In A375 cells (high N-cadherin, PTEN-expressing), Exherin alone accelerated tumor growth, which was associated with increased AKT phosphorylation. In DM443 cells (low N-cadherin, PTEN-null), it had no significant effect on growth. Despite this dichotomous effect, Exherin consistently increased tumor vascular permeability (by ~30%) in both xenograft models, leading to enhanced delivery of the protein-bound drug melphalan (LPAM) and improving its anti-tumor efficacy. This benefit did not extend to temozolomide (TMZ), which is less protein-bound. The study highlights the complexity of targeted therapies and the importance of understanding context-dependent effects, including the potential for both therapeutic benefit and harm. The findings have significant clinical relevance for ongoing and future trials combining N-cadherin antagonists with regional chemotherapy. [3]

C22H34N8O6S2

570.68

570.204

229971-81-7

ADH-1 trifluoroacetate;1135237-88-5

9916058

White to off-white solid powder

1.4±0.1 g/cm3

1183.4±65.0 °C at 760 mmHg

669.5±34.3 °C

0.0±0.3 mmHg at 25°C

1.619

-2.35

7

9

5

38

907

5

C[C@H]1C(=O)N[C@H](C(=O)N[C@@H](CSSC[C@@H](C(=O)N[C@H](C(=O)N1)CC2=CN=CN2)NC(=O)C)C(=O)N)C(C)C

FQVLRGLGWNWPSS-BXBUPLCLSA-N

InChI=1S/C22H34N8O6S2/c1-10(2)17-22(36)29-15(18(23)32)7-37-38-8-16(27-12(4)31)21(35)28-14(5-13-6-24-9-25-13)20(34)26-11(3)19(33)30-17/h6,9-11,14-17H,5,7-8H2,1-4H3,(H2,23,32)(H,24,25)(H,26,34)(H,27,31)(H,28,35)(H,29,36)(H,30,33)/t11-,14-,15-,16-,17-/m0/s1

(4R,7S,10S,13S,16R)-16-acetamido-13-(1H-imidazol-5-ylmethyl)-10-methyl-6,9,12,15-tetraoxo-7-propan-2-yl-1,2-dithia-5,8,11,14-tetrazacycloheptadecane-4-carboxamide

ADH-1; ADH 1; NSC729477; ADH1; Brand name: Exherin; Exherin free base;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: (1). This product is not stable in solution, please use freshly prepared working solution for optimal results.  (2). Please store this product in a sealed and protected environment, avoid exposure to moisture.

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

DMSO : ~250 mg/mL (~438.07 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (3.64 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% 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 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.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (3.64 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.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (3.64 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.

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 (Please use freshly prepared in vivo formulations for optimal results.)