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 conclusion, the PBPK model adequately captured the PK profiles of acalabrutinib and its active metabolite ACP‐5862 as well as parent, metabolite, and total parent and metabolite (total active component) exposure in drug interactions with CYP3A inhibitors and inducers. The model indicated that there was little change in exposure to total active component in the presence of strong or moderate CYP3A inhibitors and only a 50% decrease in exposure to total active components in the presence of a strong CYP3A inducer. The PBPK model guided package insert dose change recommendations for CYP3A inhibitors and inducers and also showed that acalabrutinib is unlikely to perpetrate a drug interaction on sensitive CYP2C8 or CYP3A substrates.[2]

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Acalabrutinib, a selective, covalent Bruton tyrosine kinase inhibitor, is a CYP3A substrate and weak CYP3A/CYP2C8 inhibitor. A physiologically-based pharmacokinetic (PBPK) model was developed for acalabrutinib and its active metabolite ACP-5862 to predict potential drug-drug interactions (DDIs). The model indicated acalabrutinib would not perpetrate a CYP2C8 or CYP3A DDI with the sensitive CYP substrates rosiglitazone or midazolam, respectively. The model reasonably predicted clinically observed acalabrutinib DDI with the CYP3A perpetrators itraconazole (4.80-fold vs. 5.21-fold observed) and rifampicin (0.21-fold vs. 0.23-fold observed). An increase of two to threefold acalabrutinib area under the curve was predicted for coadministration with moderate CYP3A inhibitors. When both the parent drug and active metabolite (total active components) were considered, the magnitude of the CYP3A DDI was much less significant. PBPK dosing recommendations for DDIs should consider the magnitude of the parent drug excursion, relative to safe parent drug exposures, along with the excursion of total active components to best enable safe and adequate pharmacodynamic coverage.[2]

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Acalabrutinib (ACP-196) is a novel, potent, and highly selective Bruton tyrosine kinase (BTK) inhibitor, which binds covalently to Cys481 in the ATP-binding pocket of BTK. We sought to evaluate the antitumor effects of acalabrutinib treatment in two established mouse models of chronic lymphocytic leukemia (CLL).Experimental Design: Two distinct mouse models were used, the TCL1 adoptive transfer model where leukemic cells from Eμ-TCL1 transgenic mice are transplanted into C57BL/6 mice, and the human NSG primary CLL xenograft model. Mice received either vehicle or acalabrutinib formulated into the drinking water.Results: Utilizing biochemical assays, we demonstrate that acalabrutinib is a highly selective BTK inhibitor as compared with ibrutinib. In the human CLL NSG xenograft model, treatment with acalabrutinib demonstrated on-target effects, including decreased phosphorylation of PLCγ2, ERK, and significant inhibition of CLL cell proliferation. Furthermore, tumor burden in the spleen of the mice treated with acalabrutinib was significantly decreased compared with vehicle-treated mice. Similarly, in the TCL1 adoptive transfer model, decreased phosphorylation of BTK, PLCγ2, and S6 was observed. Most notably, treatment with acalabrutinib resulted in a significant increase in survival compared with mice receiving vehicle.Conclusions: Treatment with acalabrutinib potently inhibits BTK in vivo, leading to on-target decreases in the activation of key signaling molecules (including BTK, PLCγ2, S6, and ERK). In two complementary mouse models of CLL, acalabrutinib significantly reduced tumor burden and increased survival compared with vehicle treatment. Overall, acalabrutinib showed increased BTK selectivity compared with ibrutinib while demonstrating significant antitumor efficacy in vivo on par with ibrutinib. 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.

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