Background: The results of Aspirin prevention of colorectal adenomas in patients with familial adenomatous polyposis (FAP) are controversial. Methods: We conducted a biomarker-based clinical study in eight FAP patients treated with enteric-coated low-dose Aspirin (100 mg daily for three months) to explore whether the drug targets mainly platelet cyclooxygenase (COX)-1 or affects extraplatelet cellular sources expressing COX-isozymes and/or off-target effects in colorectal adenomas. Results: In FAP patients, low-dose Aspirin-acetylated platelet COX-1 at Serine529 (>70%) was associated with an almost complete inhibition of platelet thromboxane (TX) B₂ generation ex vivo (serum TXB₂). However, enhanced residual urinary 11-dehydro-TXB₂ and urinary PGEM, primary metabolites of TXA₂ and prostaglandin (PG)E₂, respectively, were detected in association with incomplete acetylation of COX-1 in normal colorectal biopsies and adenomas. Proteomics of adenomas showed that Aspirin significantly modulated only eight proteins. The upregulation of vimentin and downregulation of HBB (hemoglobin subunit beta) distinguished two groups with high vs. low residual 11-dehydro-TXB₂ levels, possibly identifying the nonresponders and responders to Aspirin. Conclusions: Although low-dose Aspirin appropriately inhibited the platelet, persistently high systemic TXA₂ and PGE₂ biosynthesis were found, plausibly for a marginal inhibitory effect on prostanoid biosynthesis in the colorectum. Novel chemotherapeutic strategies in FAP can involve blocking the effects of TXA₂ and PGE₂ signaling with receptor antagonists.

Therapeutic drug monitoring (TDM) is becoming increasingly essential in cystic fibrosis (CF), as a growing number of children and adults are now eligible for elexacaftor/tezacaftor/ivacaftor (ETI) CF Transmembrane conductance Regulator (CFTR) modulator therapies. Although plasma remains the benchmark, its invasive nature limits practical use. Analytical approaches based on dried matrices currently available still rely on venipuncture and intensive workflows. To overcome these limitations, we developed an advanced, multidimensional TDM framework for ETI quantification that incorporates truly venipuncture-free, self-collected, and quantitative dried blood spot (DBS) sampling, along with non-invasive nasal airway swabs (NAS) and sweat. We also evaluated ETI in airway and sweat fluids, offering insight into drug distribution and activity at key target tissues. Selectivity, specificity, linearity, accuracy, precision, and inter/intraday stability of the methods applied to plasma, NAS, and sweat specimens were investigated according to ICH M10 guidelines and IATDMCT for DBS. Analytical performance of the methods in all tested matrices were demonstrated and met the acceptance criteria of ICH M10 guidelines for bioanalytical-method validation, with DBS additionally fulfilling the IATDMCT DBS-specific recommendations. DBS measurements were statistically equivalent to plasma concentrations, supporting their utility as a minimally invasive surrogate for TDM. ETI levels in NAS were significantly higher than in plasma or sweat, indicating localized accumulation of the drug on the airway surface, a key site of CFTR activity. Sweat samples, while showing lower analyte amounts, contained detectable levels in all analytes within their biologically active concentrations. This integrated analytical approach provides a holistic view of systemic and local ETI distribution, increasing the potential for personalized TDM, pharmacokinetics/pharmacodynamics study, and optimization of CFTR modulator therapy.