The impact of body mass index (BMI) on treatment outcomes in patients with cancer is gaining increasing attention given the limited data available. The aim of this study was to investigate the contribution of BMI on the safety and efficacy profile of palbociclib in 134 patients with metastatic luminal-like breast cancer treated with palbociclib and endocrine therapy (ET). Normal-weight and underweight patients (BMI<25) were compared with overweight and obese (BMI≥25). Detailed clinical and demographic data were collected. Patients with a BMI<25 had a higher incidence of relevant-hematologic toxicities (p = 0.001), dose reduction events (p = 0.003), and tolerated lower dose intensities (p = 0.023) compared to patients with a BMI≥25. In addition, patients with a BMI<25 had significantly shorter progression-free survival (log-rank p = 0.0332). A significant difference was observed in the subgroup of patients for whom systemic palbociclib concentrations were available: patients with a BMI<25 had a 25% higher median minimum plasma concentrations (C_min) compared to BMI≥25. This study provides compelling evidence for a clinically relevant contribution of BMI in discriminating a group of patients who experienced multiple toxicities that appeared to affect treatment adherence and lead to poorer survival. BMI could become a valuable tool for personalizing the starting dose of palbociclib to improve its safety and efficacy.

A wide interindividual variability in therapeutic response to cyclin-dependent kinases 4 and 6 inhibitors (CDKis) palbociclib, ribociclib and abemaciclib, among patients with HR+/HER2- metastatic breast cancer has been reported. This study explored the impact of genetic polymorphisms in ADME genes (responsible for drug absorption, distribution, metabolism, and elimination) on CDKis safety profiles in 230 patients. Selected endpoints include grade 3/4 neutropenia at day 14 of the first treatment cycle, early dose-limiting toxicities (DLTs), and dose reductions within the initial three cycles. Our analysis revealed associations between these endpoints and polymorphisms in CYP3A4, CYP3A5, ABCB1, and ABCG2 genes. Their impact on CDKis plasma concentrations (C_trough) was also examined. Specifically, ABCB1 c.1236C>T and c.2677C>T polymorphisms correlated significantly with grade 3/4 neutropenia at day 14 (OR 3.94, 95% CI 1.32-11.75; p = 0.014 and OR 3.32, 95% CI 1.12-9.85; p = 0.030). Additionally, ABCB1 c.3435C>T was associated with an elevated risk of early DLTs and dose reductions (OR 3.28, 95% CI 1.22-8.84, p = 0.019; OR 2.60, 95% CI 1.20-5.60, p = 0.015). Carriers of the CYP3A4*22 allele also demonstrated in univariate a higher risk of early DLTs (OR 3.10, 95% CI 1.01-9.56, p = 0.049). Furthermore, individuals with the ABCB1 1236T-3435T-2677T(A) variant haplotype exhibited significant associations with grade 3/4 neutropenia at day 14 (OR 3.36, 95% CI 1.20-9.41; p = 0.021) and early DLTs in univariate (OR 3.08, 95% CI 1.19-7.95; p = 0.020). Homozygous carriers of the ABCB1 T-T-T(A) haplotype tended to have a higher mean ribociclib C_trough (934.0 ng/mL vs. 752.0 ng/mL and 668.0 ng/mL). Regardless preliminary, these findings offer promising insights into the role of pharmacogenetic markers in CDKis safety profiles, potentially contributing to address the interindividual variability in CDKis responses.

Aims: Pharmacogenetic implementation requires awareness of the state‐of‐the‐art practice of laboratories providing pharmacogenetic testing. This study investigated how pharmacogenetic guidelines and recommendations have been implemented over time by Italian laboratories participating in the external quality assessment (EQA) Pharmaco‐scheme established since 2019 by the European Molecular genetics Quality Network (EMQN). Methods: Anonymized clinical pharmacogenetic reports submitted by Italian laboratories participating in the EMQN Pharmaco‐scheme between 2019 and 2023 were analysed. A total of 88 reports addressing fluoropyrimidine/ DPYD and irinotecan/ UGT1A1 drug‐gene interactions were evaluated for genotyping panel adopted and methodology, referenced guidelines and accuracy of clinical interpretation. Results: Over the 5‐year period, Italian laboratories accounted for 45% of all European submissions. The adoption of DPYD and UGT1A1 testing increased significantly, with the use of the Italian Society of Pharmacology – Italian Association of Medical Oncology (SIF‐AIOM) genotyping panel rising from 0% in 2019 to 97% in 2023. The proportion of laboratories providing accurate clinical interpretations in line with at least one major guideline (the Clinical Pharmacogenetics Implementation Consortium, the Dutch Pharmacogenomics Working Group or SIF‐AIOM) increased from 34% in 2021 to 63% in 2023. Notably, only the SIF‐AIOM guidelines recommend testing for the DPYD *6 variant in a reactive setting. However, clearer guidance is needed to avoid the risk of undertreatment in these patients. Allelic discrimination emerged as the preferred genotyping method, particularly with the widespread adoption of commercial European Union‐marked in vitro diagnostic kits. Conclusions: This study provides a snapshot of pharmacogenetic testing practices in Italian laboratories participating in an EQA programme. It highlights an encouraging trend toward improved accuracy and guideline adherence, reflecting increasing awareness and harmonization in clinical pharmacogenetic practice.

Objectives: Treatment of metastatic colorectal cancer (mCRC) includes resection of liver metastases (LM), however, no validated biomarker identifies patients most likely to benefit from this procedure. This meta-analysis aimed to assess the impact of the most relevant molecular alterations in cancer-related genes of CRC (i.e., RAS, BRAF, SMAD4, PIK3CA) as prognostic markers of survival and disease recurrence in patients with mCRC surgically treated by LM resection. Methods: A systematic literature review was performed to identify studies reporting data regarding survival and/or recurrence in patients that underwent complete liver resection for CRC LM, stratified according to RAS, BRAF, PIK3CA, and SMAD4 mutational status. Hazard ratios (HRs) from multivariate analyses were pooled in the meta-analysis and various adjustment strategies for confounding factors were combined. The search was conducted in numerous databases, including MEDLINE (PubMed), Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL) (EBSCO host), and WHO Global Index Medicus, through March 18th, 2022. Meta-analyses, editorials, letters to the editor, case reports, studies on other primary cancers, studies with primary metastatic sites other than the liver, studies lacking specific oncological outcome variables or genetic data, non-English language studies, and studies omitting residual disease data from liver metastasectomy were excluded. The remaining 47 studies were summarized in a descriptive table which outlines the key characteristics of each study and final results were graphically presented. Results: RAS mutation status was negatively associated with overall survival (OS) (HR, 1.68; 95% CI, 1.54–1.84) and recurrence free survival (RFS) (HR, 1.46; 95% CI, 1.33–1.61). A negative association was also found for BRAF regarding OS (HR, 2.64; 95% CI, 2.15–3.24) and RFS (HR, 1.89; 95% CI, 1.32–2.73) and SMAD4 regarding OS (HR, 1.93; 95% CI, 1.56–2.38) and RFS (HR, 1.95; 95% CI, 1.31–2.91). For PIK3CA only three studies were eligible and no significant association with either OS or RFS could be highlighted. Conclusion: RAS, BRAF, and SMAD4 are negatively associated with OS and RFS in patients undergoing curative liver metastasectomy from colorectal cancer. No conclusion can be drawn for PIK3CA due to the limited literature availability. These data support the integration of RAS, BRAF, and SMAD4 mutational status in the surgical decision-making for colorectal liver metastasis. Nevertheless, we have to consider several limitations, the major ones being the pooling of results from studies that evaluated patient outcomes as either disease-free survival (DFS) or RFS; the inclusion of patients with minimal residual disease and unconsidered potential confounding factors, such as variability in resectability definitions, chemotherapy use, and a potential interaction between biological markers and pre- and post-resection pharmacological treatments.

Background: Therapeutic drug monitoring (TDM) using cyclin-dependent kinase inhibitors (CDK4/6is) is a novel approach for optimizing treatment outcomes. Currently, palbociclib, ribociclib, and abemaciclib are the available CDK4/6is and are primarily coadministered with letrozole. This study aimed to develop and validate an LC-MS/MS method for the simultaneous analysis of CDK4/6is, 2 active metabolites of abemaciclib (M2 and M20), and letrozole in human plasma for use in TDM studies. Methods: Sample pretreatment comprised protein precipitation with methanol and dilution of the supernatant with an aqueous mobile phase. Chromatographic separation was achieved using a reversed-phase XBridge BEH C18 column (2.5 μm, 3.0 × 75 mm XP), with methanol serving as the organic mobile phase and pyrrolidine–pyrrolidinium formate (0.005:0.005 mol/L) buffer (pH 11.3) as the aqueous mobile phase. A triple quadrupole mass spectrometer was used for the detection, with the ESI source switched from negative to positive ionization mode and the acquisition performed in multiple reaction monitoring mode. Results: The complete validation procedure was successfully performed in accordance with the latest regulatory guidelines. The following analytical ranges (ng/mL) were established for the tested compounds: 6–300, palbociclib and letrozole; 120–6000, ribociclib; 40–800, abemaciclib; and 20–400, M2 and M20. All results met the acceptance criteria for linearity, accuracy, precision, selectivity, sensitivity, matrix effects, and carryover. A total of 85 patient samples were analyzed, and all measured concentrations were within the validated ranges. The percent difference for the reanalyzed samples ranged from −11.2% to 7.0%. Conclusions: A simple and robust LC-MS/MS method was successfully validated for the simultaneous quantification of CDK4/6is, M2, M20, and letrozole in human plasma. The assay was found to be suitable for measuring steady-state trough concentrations of the analytes in patient samples.

Therapeutic drug monitoring (TDM) may be beneficial for cyclin-dependent kinase 4/6 inhibitors (CDK4/6is), such as palbociclib, ribociclib, and abemaciclib, due to established exposure–toxicity relationships and the potential for monitoring treatment adherence. Developing a method for quantifying CDK4/6is, abemaciclib metabolites (M2, M20), and letrozole in dried blood spots (DBS) could be useful to enhance the feasibility of TDM. Thus, an optimized LC-MS/MS method was developed using the HemaXis DB10 device for volumetric (10 µL) DBS collection. Chromatographic separation was achieved using a reversed-phase XBridge BEH C18 column. Detection was performed with a triple quadrupole mass spectrometer, utilizing ESI source switching between negative and positive ionization modes and multiple reaction monitoring acquisition. Analytical validation followed FDA, EMA, and IATDMCT guidelines, demonstrating high selectivity, adequate sensitivity (LLOQ S/N ≥ 30), and linearity (r ≥ 0.997). Accuracy and precision met acceptance criteria (between-run: accuracy 95–106%, CV ≤ 10.6%). Haematocrit independence was confirmed (22–55%),with high recovery rates (81–93%) and minimal matrix effects (ME 0.9–1.1%). The stability of analytes under home-sampling conditions was also verified. Clinical validation supports DBS-based TDM as feasible, with conversion models developed for estimating plasma concentrations (the reference for TDM target values) of letrozole, abemaciclib, and its metabolites. Preliminary data for palbociclib and ribociclib are also presented.