Brutons tyrosine kinase (BTK)

ACP‐5862 was identified as the major, and pharmacologically active, metabolite of acalabrutinib in plasma. ACP‐5862 has ~ 50% potency for BTK inactivation relative to parent acalabrutinib and has a similar kinase selectivity profile.Based on in vitro studies, acalabrutinib is a substrate of P‐glycoprotein (P‐gp) and is predominantly metabolized by CYP3A enzymes. Further metabolism of ACP‐5862 is also mainly mediated by CYP3A.[2]

The half-life of ACP-5862 is 6.9 hours following a single oral dose of 100 mg Acalabrutinib, and the average exposure is around two to three times higher than Acalabrutinib [2]. With ACP-5862 (M27) making up 42.1% and 57.4% of the total AUC0-t radioactivity in the plasma of male and female rats, respectively, it is the main single metabolite in the systemic circulation. ACP-5862, which makes up 6.1% and 8.1% of the total AUC0-t radioactivity in the plasma of male and female dogs, respectively, is a significant human metabolite and a comparatively small part of the systemic circulation [1]. In mouse, rat, dog, and human plasma, the reversible protein binding rates of ACP-5862 (1 or 10 μM) are 98.6%, 99.8%, 94.3%, and 98.6% [1].

The metabolism of acalabrutinib to ACP‐5862 was characterized in recombinant CYP enzymes, and CYP3A4 was identified as the sole enzyme responsible for the conversion of acalabrutinib to ACP‐5862. The reported maximum rate of metabolism formation (Vmax) of 4.13 pmol/minutes/pmol and Km of 2.78 μM in CYP3A4 were incorporated in the model to describe the conversion of acalabrutinib to ACP‐5862. Therefore, the elimination of acalabrutinib via CYP3A4 (9.63 μL/minutes/pmol) was further divided into two clearance pathways: one to the active metabolite ACP‐5862 (Vmax of 4.13 pmol/minutes/pmol and Km of 2.78 μM) and the other to the rest of the metabolites (8.14 μL/minutes/pmol). The in vitro studies also demonstrated that the CYP3A enzyme was responsible for the further metabolism of ACP‐5862, and a clearance value of 23.6 μL/minutes/mg protein in human liver microsomes was assigned to CYP3A4 for the elimination of ACP‐5862. A renal clearance of 0.3 L/hour for ACP‐5862 reported in ACE‐HV‐00917 was applied in the model. Such assignment suggested that the ACP‐5862–related metabolites contributed about 12% of total acalabrutinib elimination, which is in close agreement with the 10% of total dose observed in human mass balance study.[2]

[1]. The Bruton's tyrosine kinase (BTK) inhibitor acalabrutinib demonstrates potent on-target effects and efficacy in two mouse models of chronic lymphocytic leukemia. Clin Cancer Res. 2016 Nov 30.

[2]. Evaluation of the Drug-Drug Interaction Potential of Acalabrutinib and Its Active Metabolite, ACP-5862, Using a Physiologically-Based Pharmacokinetic Modeling Approach. CPT Pharmacometrics Syst Pharmacol. 2019 Jul;8(7):489-499.

In summary, the PBPK model effectively captures the pharmacokinetic characteristics of acalabrustinib and its active metabolite ACP-5862, as well as the exposure of the parent drug, metabolites, and total parent drug and metabolites (total active ingredient) in the presence of drug interactions with CYP3A inhibitors and inducers. The model shows that the exposure of the total active ingredient is almost unchanged in the presence of potent or intermediate-potency CYP3A inhibitors, while the exposure of the total active ingredient decreases by only 50% in the presence of potent CYP3A inducers. The PBPK model guides the dosage adjustment recommendations in the drug label of CYP3A inhibitors and inducers and shows that acalabrustinib is unlikely to interact with sensitive CYP2C8 or CYP3A substrates. [2]

---

Acalabrutinib is a selective covalent Bruton's tyrosine kinase inhibitor, a CYP3A substrate, and a weak CYP3A/CYP2C8 inhibitor. This study established a physiologically based pharmacokinetic (PBPK) model to predict potential drug interactions (DDIs) between acalatinib and its active metabolite ACP-5862. The model showed that acalatinib does not exhibit CYP2C8 or CYP3A drug interactions with sensitive CYP substrates such as rosiglitazone or midazolam. The model accurately predicted clinically observed drug interactions between acalatinib and the CYP3A inhibitors itraconazole (predicted 4.80-fold, observed 5.21-fold) and rifampin (predicted 0.21-fold, observed 0.23-fold). The model predicted that the area under the curve (AUC) of acalatinib would increase by 2 to 3 times when co-administered with intermediate-acting CYP3A inhibitors. The degree of CYP3A drug interaction was significantly reduced when both the parent drug and the active metabolite (total active ingredient) were considered. Physiological pharmacokinetic (PBPK) dosing recommendations for drug interactions (DDI) should take into account the range of parent drug concentration fluctuations (relative to safe parent drug exposure) and the range of total active ingredient concentration fluctuations to maximize safe and adequate pharmacodynamic coverage. [2]

---

Acalabrutinib (ACP-196) is a novel, potent and selective Bruton's tyrosine kinase (BTK) inhibitor that covalently binds to Cys481 in the BTK ATP binding pocket. We aimed to evaluate the antitumor effects of aalabrutinib treatment in two established mouse models of chronic lymphocytic leukemia (CLL). Experimental design: We used two different mouse models, one was the TCL1 adoptive transfer model (leukemia cells from Eμ-TCL1 transgenic mice were transplanted into C57BL/6 mice), and the other was the human NSG primary CLL xenograft model. Mice received either the carrier or aalabrutinib formulation dissolved in drinking water. Results: Biochemical analysis confirmed that acalabrutinib is a highly selective BTK inhibitor compared to ibrutinib. In a human CLL NSG xenograft model, acalabrutinib treatment showed targeted effects, including reduced PLCγ2 and ERK phosphorylation levels and significant inhibition of CLL cell proliferation. Furthermore, compared to the vector-treated mice, the acalabrutinib-treated mice exhibited a significantly reduced splenic tumor burden. Similarly, reduced BTK, PLCγ2, and S6 phosphorylation levels were observed in the TCL1 adoptive transfer model. Most notably, mice treated with acalabrutinib showed significantly prolonged survival compared to those treated with the vector. Conclusion: Acalabrutinib effectively inhibits BTK in vivo, thereby targeting and reducing the activation of key signaling molecules, including BTK, PLCγ2, S6, and ERK. In two complementary CLL mouse models, acalabrutinib significantly reduced tumor burden and prolonged survival compared to vector treatment. Overall, acalabrutinib exhibited higher BTK selectivity compared to ibrutinib, while demonstrating comparable significant antitumor efficacy in vivo. (Clin Cancer Res; 23(11); 2831-41)

C26H23N7O3

481.505924463272

481.18623

C, 64.85; H, 4.81; N, 20.36; O, 9.97

2230757-47-6

ACP-5862-d4

135177281

White to off-white solid powder

2.8

3

7

8

36

860

0

O=C(CCCNC(C#CC)=O)C1=NC(C2C=CC(C(NC3C=CC=CN=3)=O)=CC=2)=C2C(N)=NC=CN21

XZAATUBTUPPERZ-UHFFFAOYSA-N

XZAATUBTUPPERZ-UHFFFAOYSA-N

4-(8-amino-3-(4-(but-2-ynamido)butanoyl)imidazo[1,5-a]pyrazin-1-yl)-N-(pyridin-2-yl)benzamide

ACP-5862; ACP 5862; ACP-5862; 2230757-47-6; 4-[8-Amino-3-[4-(but-2-ynoylamino)butanoyl]imidazo[1,5-a]pyrazin-1-yl]-N-pyridin-2-ylbenzamide; 4-[8-Amino-3-[1-oxo-4-[(1-oxo-2-butyn-1-yl)amino]butyl]imidazo[1,5-a]pyrazin-1-yl]-N-2-pyridinyl-benzamide; SCHEMBL20327799; BDBM474105; GLXC-26720; US10858364, formula (I); ACP5862

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

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 (~519.20 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (4.32 mM) (saturation unknown) in 10% DMSO + 40% PEG300 +5% Tween-80 + 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.

---

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