The pharmacological advantage of prolonged dose rate gemcitabine is restricted to patients with variant alleles of cytidine deaminase c.79A>C

A systematic review and meta-analysis of the impacts of germline pharmacogenomics on severe toxicity and symptom burden in adult patients with cancer

The clinical application of Pharmacogenomics (PGx) has improved patient safety. However, comprehensive PGx testing has not been widely adopted in clinical practice, and significant opportunities exist to further optimize PGx in cancer care. This systematic review and meta-analysis aim to evaluate the safety outcomes of reported PGx-guided strategies (Analysis 1) and identify well-studied emerging pharmacogenomic variants that predict severe toxicity and symptom burden (Analysis 2) in patients with cancer. We searched MEDLINE, EMBASE, CENTRAL, clinicaltrials.gov, and International Clinical Trials Registry Platform from inception to January 2023 for clinical trials or comparative studies evaluating PGx strategies or unconfirmed pharmacogenomic variants. The primary outcomes were severe adverse events (SAE; ≥ grade 3) or symptom burden with pain and vomiting as defined by trial protocols and assessed by trial investigators. We calculated pooled overall relative risk (RR) and 95% confidence interval (95%CI) using random effects models. PROSPERO, registration number CRD42023421277. Of 6811 records screened, six studies were included for Analysis 1, 55 studies for Analysis 2. Meta-analysis 1 (five trials, 1892 participants) showed a lower absolute incidence of SAEs with PGx-guided strategies compared to usual therapy, 16.1% versus 34.0% (RR = 0.72, 95%CI 0.57-0.91, p = 0.006, I2 = 34%). Meta-analyses 2 identified nine medicine(class)-variant pairs of interest across the TYMS, ABCB1, UGT1A1, HLA-DRB1, and OPRM1 genes. Application of PGx significantly reduced rates of SAEs in patients with cancer. Emergent medicine-variant pairs herald further research into the expansion and optimization of PGx to improve systemic anti-cancer and supportive care medicine safety and efficacy.

The Rate of Infusion Represents an Important Aspect of Administering Anticancer Agents

Background

Infusion rate is one of the essential elements that should be included in all intravenous orders. Patients may experience adverse consequences or risks associated with inappropriate infusion. Meanwhile, there is growing pressure on the chemotherapy unit to deliver treatment quickly, efficiently, and safely, and thus it is very necessary to improve the chemotherapy process and service to cancer patients. Clinicians should consider how to further standardize infusion therapy, and innovate new infusion strategies to increase efficacy, reduce toxicity, improve patient satisfaction and save health resource costs. Sporadic studies have evaluated the effects of infusion rates of anticancer agents on clinical outcomes, economic benefits, and administration efficiency. However, an update review has not been available.

Methods

Relevant literature was identified by search of PubMed until September 2023.

Results

Infusion rates may have significant effect on the efficacy of anticancer agents (e.g., methotrexate, fluorouracil, and arsenic trioxide). Slow infusion is safer for platinum compounds, doxorubicin and carmustine, whereas fast infusion is safer than slow infusion of gemcitabine. Optimal flow rates of paclitaxel and fluorouracil are based on the balance between multiple risks of toxicity. Optimal infusion rate may bring economic benefits. If efficacy and safety are not compromised, shortened infusion may result in higher patient satisfaction, improved institutional efficiency and more nursing time available for other activities (e.g., biosimilar products, endostar). Other concerns about infusion rate include clinical indications (eg, paclitaxel and rituximab, methotrexate), severity and type of hypersensitivity reactions (e.g., platinum compounds), formulation features (e.g., paclitaxel, doxorubicin), and genetic polymorphism (e.g., gemcitabine, methotrexate).

Conclusion

The latest knowledge of infusion rate concerns will enhance the appropriateness and accuracy in intravenous administration. Interdisciplinary teams should collaborate and implement relevant risk management and healthcare policy. It is worthwhile to conduct comparative studies of intravenous therapy with different infusion speeds.

Prolonged low-dose infusion for gemcitabine: a systematic review

Background

The present standard dose of gemcitabine (Gem), a pyrimidine antimetabolite, is 1,000-1,250 mg/m², and the infusion time is 30 min. However, pharmacological studies have demonstrated that Gem with prolonged infusion could attain a better accumulation rate of Gem triphosphate (active metabolites of Gem), indicating that Gem with prolonged infusion is superior to 30-min infusion. Thus, this systematic review aims to provide some references for Gem administered as a prolonged infusion.

Methods

We searched electronic databases, including PubMed, EMBASE, Cochrane Library, and CNKI, for trials. Keywords were "Gem," "prolonged infusion," and "low-dose." In addition, we used the Cochrane Handbook V5.1.0 and methodological index for non-randomized studies to evaluate the quality of randomized controlled trials (RCTs) and non-RCTs, respectively. Furthermore, Cochrane Collaboration guidelines and the PRISMA statement were adopted.

Results

We systematically reviewed 19 studies (5 RCTs and 14 non-RCTs). All studies assessed the efficacy and safety of Gem administered as a prolonged low-dose infusion (P-LDI) and reported that Gem administered as P-LDI was effective and well tolerated.

Conclusion

Gem administered as P-LDI is effective, safe, and economical, especially suited for patients with poor performance status or without good economic condition.

Cytidine deaminase polymorphism predicts toxicity of gemcitabine-based chemotherapy

BACKGROUND

The aim of this study was to ascertain whether single nucleotide polymorphisms of cytidine deaminase (CDA), a key enzyme in the metabolism pathway of gemcitabine, could predict clinical outcomes of cancer patients with gemcitabine-based chemotherapy.

METHODS

We searched MEDLINE and EMBASE up to January 2013 to identify eligible studies. A rigorous quality assessment of eligible studies was conducted according to the Newcastle-Ottawa Quality Assessment Scale. For each included study, the overall survival (OS), overall response rate (ORR) and toxicities were extracted and pooled using random-effects model.

RESULTS

In total, data from 13 studies were included. CDA 208A>G and CDA 435C>T were not included in quantified synthesis due to limited data. CDA 79A>C polymorphism was not significantly associated with OS; however, patients carrying the variant CDA 79C allele were likely to have a poor survival, hazard ratio (HR)=1.03, 95% CI 0.957-1.27 (AC+CC vs. AA). CDA 79A>C polymorphism did not correlated with ORR, odds ratio (OR)=0.719, 95% CI 0.363-1.425 (AC+CC vs. AA). However, patients with the variant CDA 79C allele would experience more grade ≥ 3 leucopenia (OR=2.933, 95% CI 1.357-6.605) and tended to have more severe neutropenia (OR=1.313, 95% CI 0.157-10.981).

CONCLUSIONS

These results suggest that CDA 79A>C polymorphisms is a potential biomarker for toxicity of gemcitabine-based chemotherapy and a CDA testing before gemcitabine administration is preferred.

SLC28A3 genotype and gemcitabine rate of infusion affect dFdCTP metabolite disposition in patients with solid tumours

Background:

Gemcitabine is used for the treatment of several solid tumours and exhibits high inter-individual pharmacokinetic variability. In this study, we explore possible predictive covariates on drug and metabolite disposition.

Methods:

Forty patients were enrolled. Gemcitabine and dFdU concentrations in the plasma and dFdCTP concentrations in peripheral blood mononuclear cell were measured to 72 h post infusion, and pharmacokinetic parameters were estimated by nonlinear mixed-effects modelling. Patient-specific covariates were tested in model development.

Results:

The pharmacokinetics of gemcitabine was best described by a two-compartment model with body surface area, age and NT5C2 genotype as significant covariates. The pharmacokinetics of dFdU and dFdCTP were adequately described by three-compartment models. Creatinine clearance and cytidine deaminase genotype were significant covariates for dFdU pharmacokinetics. Rate of infusion of <25 mg m⁻² min⁻¹ and the presence of homozygous major allele for SLC28A3 (CC genotype) were each associated with an almost two-fold increase in the formation clearance of dFdCTP.

Conclusion:

Prolonged dFdCTP systemic exposures (⩾72 h) were commonly observed. Infusion rate <25 mg m⁻² min⁻¹ and carriers for SLC28A3 variant were each associated with about two-fold higher dFdCTP formation clearance. The impacts of these covariates on treatment-related toxicity in more selected patient populations (that is, first-line treatment, single disease state and so on) are not yet clear.

Increased CDA expression/activity in males contributes to decreased cytidine analog half-life and likely contributes to worse outcomes with 5-azacytidine or decitabine therapy

PURPOSE

The cytidine analogs 5-azacytidine and decitabine, used to treat myelodysplastic syndromes (MDS), produce a molecular epigenetic effect, depletion of DNA-methyltransferase 1 (DNMT1). This action is S-phase dependent. Hence, genetic factors that decrease the half-lives of these drugs could impact efficacy. Documentation of such impact, and elucidation of underlying mechanisms, could lead to improved clinical application.

EXPERIMENTAL DESIGN

Cytidine deaminase (CDA) rapidly inactivates 5-azacytidine/decitabine. The effect of CDA SNP A79C and gender on CDA expression, enzyme activity, and drug pharmacokinetics/pharmacodynamics was examined in mice and humans, and the impact on overall survival (OS) was evaluated in 5-azacytidine/decitabine-treated patients with MDS (n = 90) and cytarabine-treated patients with acute myeloid leukemia (AML) (n = 76).

RESULTS

By high-performance liquid chromatography (HPLC), plasma CDA activity was decreased as expected in individuals with the SNP A79C. Interestingly and significantly, there was an even larger decrease in females than in males. Explaining this decrease, liver CDA expression was significantly lower in female versus male mice. As expected, decitabine plasma levels, measured by mass spectrometry, were significantly higher in females. In mathematical modeling, the detrimental impact of shorter drug half-life (e.g., in males) was greater in low compared with high S-phase fraction disease (e.g., MDS vs. AML), because in high S-phase fraction disease, even a short exposure treats a major portion of cells. Accordingly, in multivariate analysis, OS was significantly worse in male versus female patients with MDS treated with 5-azacytidine/decitabine.

CONCLUSIONS

Increased CDA expression/activity in males contributes to decreased cytidine analog half-life and likely contributes to worse outcomes with 5-azacytidine or decitabine therapy.

Chemotherapy-induced toxicity is highly heritable in Drosophila melanogaster

OBJECTIVES

Identification of the genes responsible for chemotherapy toxicity in Drosophila melanogaster may allow for the identification of human orthologs that similarly mediate toxicity in humans. To develop D. melanogaster as a model of dissecting chemotoxicity, we first need to develop standardized high-throughput toxicity assays and prove that the interindividual variation in toxicity as measured by such assays is highly heritable.

METHODS

We developed a method for the oral delivery of commonly used chemotherapy drugs to Drosophila. Post-treatment female fecundity displayed a dose-dependent response to varying levels of the chemotherapy drug delivered. We fixed the dose for each drug at a level that resulted in a 50% reduction in fecundity and used a paternal half-sibling heritability design to calculate the heritability attributable to chemotherapy toxicity assayed by a decrease in female fecundity. The chemotherapy agents tested were carboplatin, floxuridine, gemcitabine hydrochloride, methotrexate, mitomycin C, and topotecan hydrochloride.

RESULTS

We found that six currently widely prescribed chemotherapeutic agents lowered fecundity in D. melanogaster in both a dose-dependent and a highly heritable manner. The following heritability estimates were found: carboplatin, 0.72; floxuridine, 0.52; gemcitabine hydrochloride, 0.72; methotrexate, 0.99; mitomycin C, 0.64; and topotecan hydrochloride, 0.63.

CONCLUSION

The high heritability estimates observed in this study, irrespective of the particular class of drug examined, suggest that human toxicity may also have a sizable genetic component.

Drug interactions: the importance of looking inside cancer cells

nab-Paclitaxel increased intratumoral gemcitabine levels by reactive oxygen species-mediated degradation of cytidine deaminase, the rate-limiting enzyme in gemcitabine inactivation. This not only has implications for how this drug combination mediates anticancer effects but also demonstrates the importance of evaluating mechanisms of drug activity within malignant cells.

High incidence of severe neutropenia after gemcitabine-based chemotherapy in Chinese cancer patients with CDA 79A>C mutation

Cytidine deaminase (CDA) is a crucial enzyme in gemcitabine inactivation. Mutations in CDA gene have been found to influence the activity of CDA enzyme, which might lead to altered pharmacokinetics profile and clinical outcome of gemcitabine. In this study, the screening for the presence of CDA 79A>C and CDA 208G>A was performed by allele-specific PCR and restriction fragment length polymorphism, respectively. No difference in CDA allele frequencies was found between Chinese cancer patients and healthy volunteers. The frequencies for CDA 79A>C and 208G>A in the studied population were 12.2% and 1.0%, respectively. While a high incidence of grade 3-4 neutropenia was noted as 5 out of 8 (62.5%) patients heterozygous or homozygous for CDA 79A>C mutation developed it, in patients homozygous for the wild-type allele, the incidence was only 17.2% (5 out of 29) (p=0.021). Our study suggests that CDA 79A>C mutation might be a potential risk factor of gemcitabine-induced neutropenia toxicity.