DOCETAKEN 120

Indications

• Adjuvant treatment of operable node-positive and operable node-negative breast cancer (in combination with doxorubicin and cyclophosphamide)
• Initial chemotherapy of metastatic breast cancer which overexpresses HER2 (in combination with trastuzumab and pertuzumab)
• Treatment of hormone-refractory metastatic prostate cancer (in combination with prednisone or prednisolone)
• Initial chemotherapy of unresectable, locally advanced or metastatic non-small cell lung cancer (with cisplatin)
• Induction treatment of locally advanced squamous cell carcinoma of the head and neck (with cisplatin and fluorouracil)
• Treatment of metastatic gastric adenocarcinoma (with cisplatin and fluorouracil)

Mechanism of action

Docetaxel binds to the beta-subunit of tubulin, promoting the assembly of microtubules while preventing their disassembly. This hyper-stabilization disrupts the dynamic instability required for normal cellular functions, particularly mitosis, leading to the formation of dysfunctional microtubule bundles and ultimately causing programmed cell death (apoptosis) in cancer cells.

Pharmacodynamics

As an antineoplastic agent, docetaxel enhances microtubule stability, inhibiting the normal reorganization necessary for cell cycle progression and mitotic functions. This results in the accumulation of abnormal microtubule structures, contributing to cell cycle arrest and apoptosis. Docetaxel's use is associated with several potential adverse effects, including hematologic toxicity, hypersensitivity reactions, and fluid retention.

Pharmacokinetics

Docetaxel is administered via intravenous infusion and has a variable pharmacokinetic profile affected by hepatic function. It is metabolized primarily by the liver through CYP3A4 enzymes, and the elimination half-life is approximately 36 hours. Drug interactions, particularly with agents that affect CYP3A4, can significantly alter docetaxel exposure.

Contra-indications

• Severe hypersensitivity to docetaxel or any component of the formulation
• Severe hepatic impairment
• Acute porphyrias

Adverse effects

• Abdominal pain
• Alopecia
• Anaemia
• Appetite decreased
• Arrhythmia
• Asthenia
• Constipation
• Diarrhoea
• Dyspnoea
• Fluid imbalance
• Haemorrhage
• Hypersensitivity reactions
• Hypertension
• Hypotension
• Increased risk of infection
• Myalgia
• Nausea
• Neutropenia
• Pain
• Peripheral neuropathy
• Sepsis
• Skin reactions
• Stomatitis
• Taste altered
• Thrombocytopenia
• Vomiting
• Gastrointestinal disorders
• Heart failure
• Ascites
• Bone marrow depression
• Chest tightness
• Chills
• Cutaneous lupus erythematosus
• Disseminated intravascular coagulation
• Eye disorders
• Eye inflammation
• Fever
• Hearing impairment
• Hepatitis
• Hyponatraemia
• Loss of consciousness
• Multi-organ failure
• Myocardial infarction
• Nail discolouration
• Neurotoxicity

Interactions

• Pitolisant (severe, decreases exposure)
• Miconazole (moderate, increases concentration)
• Berotralstat (moderate, increases concentration)
• Cobicistat (moderate, increases exposure)
• Idelalisib (moderate, increases exposure)
• Clarithromycin (moderate, increases exposure)
• Sotorasib (moderate, increases exposure)
• Tucatinib (moderate, increases exposure)
• Dronedarone (unknown, increases exposure)
• Amiodarone (unknown, increases exposure)

Precautions

• Monitor liver function in hepatic impairment
• Risk of severe hematologic effects
• Risk of hypersensitivity reactions

Mechanism of action

Docetaxel interferes with the normal function of microtubule growth. Whereas drugs like [colchicine] cause the depolymerization of microtubules in vivo, docetaxel arrests their function by having the opposite effect; it hyper-stabilizes their structure. This destroys the cell's ability to use its cytoskeleton in a flexible manner. Specifically, docetaxel binds to the β-subunit of tubulin. Tubulin is the "building block" of microtubules, and the binding of docetaxel locks these building blocks in place. The resulting microtubule/docetaxel complex does not have the ability to disassemble. This adversely affects cell function because the shortening and lengthening of microtubules (termed dynamic instability) is necessary for their function as a transportation highway for the cell. Chromosomes, for example, rely upon this property of microtubules during mitosis. Further research has indicated that docetaxel induces programmed cell death (apoptosis) in cancer cells by binding to an apoptosis-stopping protein called Bcl-2 (B-cell leukemia 2), thus arresting its function. Docetaxel is an antineoplastic agent that acts by disrupting the microtubular network in cells that is essential for mitotic and interphase cellular functions. Docetaxel binds to free tubulin and promotes the assembly of tubulin into stable microtubules while simultaneously inhibiting their disassembly. This leads to the production of microtubule bundles without normal function and to the stabilization of microtubules, which results in the inhibition of mitosis in cells. Docetaxel's binding to microtubules does not alter the number of protofilaments in the bound microtubules, a feature which differs from most spindle poisons currently in clinical use. Docetaxel, a semisynthetic taxane, has exhibited significant single-agent activity against prostatic tumors. In phase I/II studies, single-agent docetaxel and the combination of docetaxel plus estramustine were effective in inducing prostate-specific antigen reductions of > or = 50% in men with androgen-independent prostate cancer (AIPC). The underlying reason for docetaxel's clinical activity against prostate cancer has been a focus of ongoing research. Docetaxel is believed to have a twofold mechanism of antineoplastic activity: (1) inhibition of microtubular depolymerization, and (2) attenuation of the effects of bcl-2 and bcl-xL gene expression. Taxane-induced microtubule stabilization arrests cells in the G(2)M phase of the cell cycle and induces bcl-2 phosphorylation, thereby promoting a cascade of events that ultimately leads to apoptotic cell death. In preclinical studies, docetaxel had a higher affinity for tubulin and was shown to be a more potent inducer of bcl-2 phosphorylation than paclitaxel. Laboratory evidence also supports the clinical evaluation of docetaxel-based combinations that include agents such as trastuzumab and/or estramustine. The pathways for docetaxel-induced apoptosis appear to differ in androgen-dependent and androgen-independent prostate cancer cells. Further elucidation of these differences will be instrumental in designing targeted regimens for the treatment of localized and advanced prostate cancer.

Pharmacodynamics

Docetaxel is a taxoid antineoplastic agent. It promotes the assembly of microtubules from tubulin dimers and stabilizes microtubules by preventing depolymerization. This stability results in the inhibition of the normal dynamic reorganization of the microtubule network which is essential for vital interphase and mitotic cellular functions. In addition, docetaxel induces abnormal arrays or "bundles" of microtubules throughout the cell cycle and multiple asters of microtubules during mitosis. The use of docetaxel may lead to treatment-related deaths in breast cancer and non-small cell lung cancer patients, hepatic impairment, hematologic effects, enterocolitis and neutropenic colitis, hypersensitivity reactions, fluid retention, second primary malignancies, cutaneous reactions, neurologic reactions, eye disorders, asthenia, embryo-fetal toxicity, and tumor lysis syndrome.