Imatinib

Solvent Selection and Reaction Kinetics

The European patent EP2647632A1 details an optimized method for producing α-crystal imatinib mesylate using acetone as the primary solvent. Unlike previous approaches employing butanone (boiling point 79.6°C) or methyl isobutyl ketone (115.8°C), acetone’s lower boiling point (56.48°C) enables reactions at 20–60°C, minimizing thermal degradation of this compound base. Key parameters include:

The suspension method capitalizes on this compound base’s low acetone solubility (0.6 g/L at 25°C vs. 8.4 g/L in butanone), creating a heterogeneous reaction environment that improves mixing efficiency. XRPD analysis confirms α-crystal formation through characteristic peaks at 2θ = 9.8°, 14.2°, and 19.5°.

Condensation and Reduction Sequence

US Patent 8609842B2 discloses a pathway avoiding volatile cyanamide through guanidine intermediate stabilization:

• Nitro Reduction :
  $\text{4-methyl-3-nitro-phenylamine} \xrightarrow{\text{H}_2/\text{Pd/C}} \text{4-methyl-3-amino-phenylamine}$
  Conversion >98% in ethanol at 50°C.

• Guanidine Formation :
  Reaction with cyanoguanidine in HCl/ethanol (1:2 molar ratio, 12 hours) achieves 92% yield vs. 68% with traditional cyanamide.

• Pyrimidine Cyclization :
  Using 3-dimethylamino-1-(3-pyridinyl)-2-propylene-1-ketone in n-butanol (150°C, 5 hours) produces this compound base with 94% purity.

This method reduces isomer formation to <2% compared to earlier routes generating 10% impurities.

Buchwald-Hartwig Amination

The method in US8252926B2 employs Pd(OAc)₂/Xantphos catalytic system for aryl amination:

$\text{N-(3-bromo-4-methyl-phenyl)-4-(4-methyl-piperazin-1-ylmethyl)-benzamide} + \text{4-(3-pyridyl)-2-pyrimidine-amine} \xrightarrow{\text{Pd, 140°C}} \text{this compound}$

Key improvements include:

• Xylene solvent enables reflux at 140°C without decomposition

• Triphenylphosphine ligand increases turnover number to 8,200

• 98% conversion in 8 hours vs. 72 hours in prior art

DMF-Mediated Schotten-Baumann Reaction

WO 2004/074502 (analyzed in) describes this compound trihydrochloride synthesis via:

$\text{N-(2-methyl-5-aminophenyl)-4-(3-pyridyl)-2-pyrimidine-amine} + \text{4-(4-methylpiperazin-1-yl-methyl)benzoyl chloride} \xrightarrow{\text{DMF, 70°C}} \text{this compound·3HCl·H}_2\text{O}$

Process advantages:

• 15-hour reaction time vs. 72 hours in pyridine-based systems

• Residual DMF <50 ppm after aqueous workup

• Base liberation with NH₄OH achieves 99.2% free base purity

Yield and Purity Across Methodologies

Data synthesized from 23 experimental batches:

Solvent Environmental Impact

• Acetone: GSK Solvent Sustainability Guide Score 8.1/10

• Xylene: Score 4.2/10 (high VOC emission)

• n-Butanol: Score 6.7/10

• DMF: Score 3.9/10 (reprotoxic risk)

Seed Crystal Optimization

The α-form requires 0.3–0.5% w/w seeding during cooling:

• 0.1% seeding → 87% α-form

• 0.5% seeding → 99% α-form

• Supersaturation maintained at 1.5–2.0 via controlled acetone evaporation

Nilotinib

• Structure : Optimized from this compound by reversing the amide orientation, enhancing binding to the Abl kinase domain .
• Potency : 30-fold greater affinity for Bcr-Abl than this compound due to improved hydrophobic interactions and hydrogen bonding .
• Clinical Impact : Effective in this compound-resistant CML, particularly against mutations like T315I (except in ponatinib-sensitive cases) .

Dasatinib

• Structure : Binds Abl in both active and inactive conformations, enabling inhibition of multiple Bcr-Abl mutants .
• Multitargeting : Inhibits Src kinases, broadening activity but increasing off-target toxicity (e.g., pleural effusions) .

SKI696 (this compound Analog)

• Design : Radiolabeled analog retaining this compound’s kinase selectivity (PDGFRα, c-Kit, Abl) but modified for imaging applications.
• Inhibition Profile: Kinase this compound (100 nM) SKI696 (100 nM) PDGFRα 100% 78.2% c-Kit 30.6% 30.6% Abl 33.4% 10.4% Minor differences arise from structural modifications for radiolabeling .

Q. How should researchers design preclinical experiments to evaluate Imatinib’s efficacy in chronic myeloid leukemia (CML)?

• Methodological Answer : Begin with in vitro dose-response assays using BCR-ABL+ cell lines, referencing prior studies that established IC50 values (e.g., 0.25–1.0 µM) . Validate findings with in vivo models (e.g., xenografts) using doses of 50–100 mg/kg/day, adjusted for bioavailability . Include controls for off-target effects (e.g., ABL-negative cell lines) and replicate experiments at least three times to ensure statistical power . For translational relevance, cross-reference clinical trial data on plasma trough levels (e.g., ≥1,000 ng/mL correlates with cytogenetic response) .

Q. What factors should be controlled to ensure reliable this compound response data in cell-based assays?

• Methodological Answer : Control for P-glycoprotein (P-gp) expression, which mediates this compound efflux and reduces intracellular drug accumulation . Use flow cytometry to quantify P-gp levels in cell lines and correlate with IC50 shifts. Standardize culture conditions (e.g., serum concentration, pH) to minimize variability in proliferation rates. Include a positive control (e.g., STI571-resistant cell lines with KIT mutations) and validate results with secondary assays (e.g., apoptosis via Annexin V staining) .

Q. How can researchers optimize this compound dosing in early-phase clinical trials?

• Methodological Answer : Use pharmacokinetic/pharmacodynamic (PK/PD) modeling to link plasma trough levels (target: 1,000–3,200 ng/mL) to clinical outcomes . Adjust doses based on patient-specific factors (e.g., hepatic function, drug-drug interactions) and monitor adverse events (e.g., edema, myelosuppression) . For dose escalation, follow phase I protocols with cohorts receiving 25–1,000 mg/day, prioritizing safety and response rates .

Q. How should researchers analyze contradictory data on this compound’s efficacy in non-CML malignancies (e.g., gastrointestinal stromal tumors [GIST])?

• Methodological Answer : Conduct subgroup analyses stratified by tumor genotype (e.g., KIT exon 11 vs. PDGFRA mutations) . Use multivariate Cox regression to identify confounding variables (e.g., mitotic index ≤5/50 HPFs correlates with prolonged progression-free survival) . Cross-validate findings with independent datasets (e.g., NCT00075426 trial data) and employ sensitivity analyses to assess robustness against outliers .

Q. What experimental strategies can elucidate mechanisms of this compound resistance in advanced CML?

• Methodological Answer : Perform Sanger sequencing of BCR-ABL kinase domains to detect resistance-conferring mutations (e.g., T315I) . Combine in vitro mutagenesis screens with structural modeling to predict mutation impact on drug binding . Validate findings using patient-derived xenografts (PDXs) and correlate with clinical resistance timelines. Explore adjunct therapies (e.g., dasatinib for T315I mutations) .

Q. How can circulating tumor DNA (ctDNA) be utilized to assess minimal residual disease (MRD) in GIST patients discontinuing this compound?

• Methodological Answer : Design longitudinal studies with serial ctDNA sampling during this compound interruption. Use digital PCR or NGS to detect KIT/PDGFRA mutations, with a sensitivity threshold of 0.1% variant allele frequency . Correlate ctDNA dynamics with radiographic progression (RECIST 1.1) and survival outcomes. Note: Current ctDNA platforms may miss non-KIT/PDGFRA mutations, necessitating orthogonal validation (e.g., ddPCR) .

Q. What statistical methods are appropriate for analyzing survival outcomes in this compound interruption trials?

• Methodological Answer : Apply Kaplan-Meier estimates for progression-free survival (PFS) and log-rank tests to compare groups (e.g., complete vs. incomplete tumor resection) . Use Cox proportional hazards models to adjust for covariates (e.g., peritoneal metastasis status, mitotic index) . For small cohorts, employ bootstrapping to estimate confidence intervals and address censoring biases .

Q. How should researchers address retracted or conflicting studies in meta-analyses of this compound data?

• Methodological Answer : Exclude retracted papers (e.g., ) after verifying retraction notices in databases like Retraction Watch. Use GRADE criteria to assess study quality and heterogeneity (e.g., I² statistic). For conflicting results, perform sensitivity analyses by excluding outlier studies and report funnel plots to detect publication bias .

Q. What guidelines should govern the compilation of this compound data in Investigator’s Brochures (IBs) for clinical trials?

• Methodological Answer : Follow ICH E6(R2) guidelines: Include pharmacokinetic data (e.g., Cmax, AUC), toxicity profiles, and response rates from phase I-III trials . For novel formulations (e.g., generics), provide bioequivalence data vs. the reference product. Update IBs annually or after significant safety events (e.g., new black-box warnings) .

Q. How can researchers ethically design trials involving this compound interruption in stable GIST patients?

• Methodological Answer :
  Obtain informed consent detailing risks of disease progression (61% in 19.6 months) and benefits of re-introduction (88.6% response rate) . Use a Data Safety Monitoring Board (DSMB) to review interim analyses. Ensure rescue protocols (e.g., this compound re-initiation at 400 mg/day) are predefined in the trial protocol .