Dacomitinib

The preparation of dacomitinib involves several synthetic routes and reaction conditions. One method includes the following steps :

Methoxylation Reaction: N-(3-chloro-4-fluorophenyl)-7-fluoro-6-nitro-4-quinazolinamine is subjected to methoxylation in an alkali/methanol system to obtain N-(3-chloro-4-fluorophenyl)-7-methoxy-6-nitroquinazolinamine-4-amine.

Reduction Reaction: The compound obtained from the methoxylation reaction is then reduced using hydrazine hydrate to yield N-(3-chloro-4-fluorophenyl)-7-methoxyl-6-aminoquinazoline-4-amine.

Condensation Reaction: This compound is then condensed with an acyl chloride compound (2E)-4-(1-piperidyl)-2-butenoic acid hydrochloride in an N-methylpyrrolidone solvent to obtain a crude product.

Recrystallization: The crude product is refined in an ethanol-water solution to obtain this compound.

This method avoids the use of large amounts of solvent, making it more environmentally friendly and suitable for industrial production .

Key Steps:

• Hydrogenative Reduction :
  Nitroarene 1 undergoes catalytic hydrogenation to form aniline 2 in acetonitrile.

• Amidation :
  Aniline 2 reacts with butenoic acid 3 (prepared from bromide 6 ) using T3P (propane phosphonic acid anhydride) and 2,6-lutidine in acetonitrile. Reverse quenching with NaOH minimizes formamidine hydrolysis.

• Dimroth Rearrangement :
  Intermediate 4 reacts with aniline 5 in neat acetic acid at 30°C to form dacomitinib. This step avoids high-temperature conditions typically required for Dimroth rearrangements .

Metabolic Reactions

This compound undergoes extensive phase I metabolism in rat liver microsomes (RLMs), primarily via piperidine ring hydroxylation and quinazoline ring reduction . Four major metabolites and two reactive intermediates were identified using LC-MS/MS :

Phase I Metabolites:

Bioactivation Pathways:

• Iminium Ion Formation :
  Piperidine ring oxidation generates iminium intermediates, stabilized as cyano adducts (DCB495, m/z 495) with KCN .

• Aldehyde Formation :
  Oxidative dealkylation of the butenamide group produces an aldehyde intermediate, trapped as an oxime adduct (DCB362, m/z 362) with methoxylamine .

Enzyme-Mediated Reactions

This compound metabolism involves cytochrome P450 (CYP) enzymes :

• CYP2D6 : Primary enzyme for O-desmethylation (PF-05199265, active metabolite).

• CYP3A4 : Secondary pathway for oxidative metabolites.

Reactive Intermediates and Toxicity

Reactive intermediates formed during metabolism are linked to this compound’s adverse effects (e.g., hepatotoxicity) :

Elimination Pathways

• Excretion : 79% fecal (20% unchanged drug), 3% urinary (<1% unchanged) .

• Half-life : 70 hours due to extensive tissue distribution and protein binding (98%) .

First-Line Treatment for NSCLC

Dacomitinib has been approved as a first-line treatment for advanced NSCLC patients with classical EGFR mutations. The ARCHER 1050 trial demonstrated that this compound significantly improved progression-free survival (PFS) compared to gefitinib, establishing it as a standard option for this patient population .

Uncommon EGFR Mutations

Recent studies indicate that this compound is effective against NSCLC patients with uncommon EGFR mutations. A dual-center study found that patients with major uncommon mutations experienced favorable outcomes, suggesting this compound's potential beyond classical mutations .

Later-Line Treatment

This compound has shown efficacy in later-line settings for NSCLC patients who have progressed after prior therapies. A real-world study indicated that it remains well-tolerated and active in patients with various EGFR mutations, including those with brain metastases .

Recurrent Glioblastoma

This compound has also been investigated in glioblastoma patients with EGFR amplification. A Phase II trial evaluated its efficacy, revealing limited activity but some responses in specific cohorts, highlighting the need for further research into patient selection based on molecular characteristics .

Case Studies and Real-World Evidence

• Case Series on CNS Metastasis : A case series documented the effectiveness of this compound in treating CNS metastasis in NSCLC patients, demonstrating significant tumor reduction and manageable toxicity .
• Real-World Application : In a retrospective analysis involving over 100 patients treated with this compound after TKI resistance, the results showed a median PFS of approximately 4 months, indicating its potential as a subsequent therapy .

Safety Profile

This compound is generally well-tolerated, with manageable adverse effects such as diarrhea and rash being the most common. The incidence of severe adverse events is relatively low, making it a viable option for many patients.

Dacomitinib exerts its effects by irreversibly inhibiting the kinase activity of the human EGFR family (EGFR/HER1, HER2, and HER4) and certain EGFR activating mutations (exon 19 deletion and exon 21 L858R substitution) . By binding to the ATP-binding site of these receptors, this compound prevents receptor autophosphorylation and downstream signaling, leading to the inhibition of cancer cell growth and proliferation .

Dacomitinib is often compared to other EGFR inhibitors such as afatinib and gefitinib . Here are some key points of comparison:

Afatinib: Like this compound, afatinib is an irreversible EGFR inhibitor. Both drugs are used for the first-line treatment of EGFR mutation-positive NSCLC.

Gefitinib: Gefitinib is a reversible EGFR inhibitor.

These comparisons highlight the uniqueness of this compound in terms of its irreversible binding and its efficacy in treating uncommon EGFR mutations.

Dacomitinib is a second-generation, irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) primarily used in the treatment of non-small cell lung cancer (NSCLC) with specific EGFR mutations. Its mechanism of action involves covalent binding to the EGFR family members, including HER2 and HER4, leading to sustained inhibition of their kinase activity. This article aims to explore the biological activity of this compound, highlighting its efficacy, safety, and underlying mechanisms through various studies and clinical trials.

This compound irreversibly inhibits the tyrosine kinase activity of the EGFR family by forming a covalent bond with cysteine residues in the catalytic domain. This mechanism distinguishes it from reversible inhibitors, which compete for ATP binding without permanent modification. The potency of this compound has been demonstrated in various preclinical studies, showing an IC50 value as low as 6 nmol/L against wild-type and mutant EGFRs, including those with T790M resistance mutations .

Key Mechanisms:

• Covalent Bond Formation : this compound binds covalently to Cys773 in EGFR, preventing ATP binding and subsequent activation of downstream signaling pathways.
• Inhibition of Signaling Pathways : The blockade of EGFR signaling leads to reduced activation of critical pathways such as Ras-Raf-MAPK and PI3K/AKT, which are involved in cell proliferation and survival .

Phase II Trials

This compound has shown promising results in several clinical trials. For instance, the ARCHER 1050 trial demonstrated that this compound significantly improved progression-free survival (PFS) compared to gefitinib in patients with advanced NSCLC harboring sensitive EGFR mutations .

Summary of Clinical Findings:

• Objective Response Rate (ORR) : Approximately 70% in patients with EGFR mutations.
• Progression-Free Survival : Median PFS was reported at around 14.7 months for patients treated with this compound compared to 9.2 months for those on gefitinib .
• Overall Survival : The overall survival rate was also improved, although specific figures vary by study.

Case Studies

• Advanced NSCLC with Uncommon Mutations : A phase II trial investigated this compound's efficacy in patients with uncommon EGFR mutations (exons 18-21). Early results indicated that this compound could be effective in this subset, providing a new therapeutic option for patients who previously had limited treatment alternatives .
• Head and Neck Cancer : this compound has also been explored for its potential in treating squamous cell carcinoma of the head and neck (SCCHN). In preclinical models, it exhibited significant antitumor activity by downregulating HER signaling pathways and enhancing apoptosis through various mechanisms .

Safety Profile

The safety profile of this compound has been assessed across multiple studies. Common adverse effects include:

• Diarrhea
• Rash
• Fatigue
• Decreased appetite

Most side effects were manageable with dose adjustments or supportive care measures. Notably, only a small percentage (5%) of participants discontinued treatment due to adverse events .

Table: Summary of Adverse Effects

Basic Research Questions

Q. What are the primary mechanisms of action of dacomitinib in EGFR-mutated non-small cell lung cancer (NSCLC), and how do they differ from first-generation EGFR inhibitors?

• Methodological Answer: this compound irreversibly inhibits pan-ErbB receptors (EGFR, HER2, HER4) by covalently binding to cysteine residues in the kinase domain, preventing ATP binding and downstream signaling. Unlike first-generation inhibitors (e.g., gefitinib), its irreversible binding enhances target suppression. Validate mechanisms using kinase assays (e.g., MTS assays for cell viability) and Western blotting to assess phosphorylation levels of EGFR and downstream effectors (e.g., AKT, MAPK) .

Q. How should researchers design in vitro studies to evaluate this compound resistance mechanisms?

• Methodological Answer: Use dose-escalation protocols in EGFR-mutated cell lines (e.g., PC9, H1975) over 6–12 months to simulate acquired resistance. Combine RNA sequencing and CRISPR-Cas9 screens to identify resistance-associated genes (e.g., MET amplification, EMT markers). Validate findings with colony formation assays and synergy studies with secondary inhibitors (e.g., MET inhibitors) .

Advanced Research Questions

Q. What are the critical considerations for designing clinical trials evaluating this compound in patients with hepatic impairment?

• Methodological Answer:

• Population: Stratify patients by Child-Pugh classification (A/B/C) and match with healthy controls.
• PK Analysis: Collect serial blood samples up to 144 hours post-dose. Use HPLC-MS/MS for plasma concentration analysis, ensuring a lower limit of quantification (LLOQ) ≤0.1 ng/mL.
• Statistical Approach: Apply non-compartmental analysis (NCA) via openNCA software to calculate AUC, Cmax, and t1/2. Account for protein binding using rapid equilibrium dialysis (RED) .

Q. How can researchers resolve contradictions in efficacy data between this compound monotherapy and combination regimens (e.g., with radiotherapy)?

• Methodological Answer: Conduct normalized isobologram analysis (Chou-Talalay method) to quantify synergy. In SCCHN models, combine this compound (5–100 nM) with ionizing radiation (2–4 Gy). Use clonogenic survival assays and measure apoptotic markers (e.g., caspase-3 cleavage). Address variability by standardizing irradiation protocols and cell line selection (e.g., FaDu vs. UT-SCC lines) .

Q. What methodologies are recommended for assessing this compound’s impact on tumor microenvironment (TME) dynamics?

• Methodological Answer: Utilize single-cell RNA sequencing (scRNA-seq) of patient-derived xenografts (PDXs) pre- and post-treatment. Focus on immune cell infiltration (e.g., CD8+ T cells, macrophages) and cytokine profiling (e.g., IL-6, TGF-β). Validate with multiplex immunohistochemistry (IHC) and spatial transcriptomics .

Q. How should pharmacokinetic/pharmacodynamic (PK/PD) models be optimized for this compound in pediatric populations?

• Methodological Answer: Develop physiologically based pharmacokinetic (PBPK) models incorporating age-related changes in CYP3A4 activity and plasma protein binding. Validate with sparse sampling in phase I trials, leveraging Bayesian estimation for AUC prediction. Prioritize safety endpoints (e.g., rash, diarrhea) due to higher toxicity risks .

Q. Methodological and Ethical Considerations

Q. What are the best practices for ensuring reproducibility in this compound pre-clinical studies?

• Methodological Answer:

• Experimental Replicates: Use ≥3 biological replicates per condition.
• Data Transparency: Publish raw HPLC-MS/MS chromatograms and RED assay validation data as supplementary materials.
• Reference Standards: Calibrate assays with this compound and metabolite (PF-05199265) reference standards .

Q. How can researchers address ethical challenges in trials involving this compound and vulnerable populations (e.g., severe hepatic impairment)?

• Methodological Answer: Exclude patients with hepatocellular carcinoma or hepatorenal syndrome to minimize confounding risks. Obtain written informed consent with explicit disclosure of off-label use risks. Include independent data monitoring committees (IDMCs) for interim safety reviews .

Q. Data Analysis and Reporting

Q. What statistical methods are robust for analyzing this compound’s long-term survival benefits in ARCHER 1050-like trials?

• Methodological Answer: Apply Cox proportional hazards models with stratification by EGFR mutation subtype (e.g., exon 19 del vs. L858R). Use landmark analysis to mitigate immortal time bias. Report median progression-free survival (PFS) with 95% confidence intervals .

Q. How should contradictory findings in this compound’s CNS penetration data be addressed?

• Methodological Answer: Perform cerebrospinal fluid (CSF) sampling in NSCLC patients with brain metastases. Compare CSF-to-plasma ratios using tandem mass spectrometry. Adjust for blood-brain barrier integrity via contrast-enhanced MRI findings .