Dihydropyrimidine dehydrogenase mutation in neoadjuvant chemotherapy in head and neck cancers: Myth or reality?

DPYD genetic polymorphisms in non-European patients with severe fluoropyrimidine-related toxicity: a systematic review

BACKGROUND

Pre-treatment DPYD screening is mandated in the UK and EU to reduce the risk of severe and potentially fatal fluoropyrimidine-related toxicity. Four DPYD gene variants which are more prominently found in Europeans are tested.

METHODS

Our systematic review in patients of non-European ancestry followed PRISMA guidelines to identify relevant articles up to April 2023. Published in silico functional predictions and in vitro functional data were also extracted. We also undertook in silico prediction for all DPYD variants identified.

RESULTS

In 32 studies, published between 1998 and 2022, 53 DPYD variants were evaluated in patients from 12 countries encompassing 5 ethnic groups: African American, East Asian, Latin American, Middle Eastern, and South Asian. One of the 4 common European DPYD variants, c.1905+1G>A, is also present in South Asian, East Asian and Middle Eastern patients with severe fluoropyrimidine-related toxicity. There seems to be relatively strong evidence for the c.557A>G variant, which is found in individuals of African ancestry, but is not currently included in the UK genotyping panel.

CONCLUSION

Extending UK pre-treatment DPYD screening to include variants that are present in some non-European ancestry groups will improve patient safety and reduce race and health inequalities in ethnically diverse societies.

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.

Identification of DPYD variants and estimation of uracil and dihydrouracil in a healthy Indian population

Aim: This study aimed to identify DPYD variants and the related but previously unexplored phenotype (plasma uracil, dihydrouracil [DHU], and the DHU-to-uracil ratio) in a healthy adult Indian population. Methods: Healthy adult volunteers (n = 100) had their uracil and DHU levels measured and were genotyped for selected variants. Results: Among the nine variants studied, c.1906-14763G>A and c.85T>C were the most prevalent. Participants with any of the variants except for c.85T>C and c.1627A>G had a significantly lower DHU-to-uracil ratio and those with c.1905+1G>A variant had significantly increased uracil concentration compared with wild type. Conclusion: Participants with five variants were identified as having altered phenotypic measures, and 40% of the intermediate metabolizers had their phenotype in the terminal population percentiles.

A systematic review and meta-analysis of toxicity and treatment outcomes with pharmacogenetic-guided dosing compared to standard of care BSA-based fluoropyrimidine dosing

BACKGROUND

Serious and potentially life-threatening toxicities can occur following 5-fluorouracil/capecitabine exposure. Patients carrying Dihydropyrimidine Dehydrogenase (DPYD) variant alleles associated with decreased enzymatic function are at a greater risk of early/severe 5-fluorouracil/capecitabine toxicity. The objective of this systematic review/meta-analysis was to evaluate treatment outcomes between Pharmacogenetics Guided Dosing (PGD) versus non-PGD and within PGD (DPYD variant allele carriers versus wild type).

METHODS

A systematic review/meta-analysis of original publications indexed in Ovid Medline, Ovid Embase, and the Cochrane CENTRAL (Wiley) library from inception to 7-Dec-2020. Eligible studies evaluated at least one pre-defined treatment outcome measures (toxicity/hospitalisations/survival/overall response/quality of life).

RESULTS

Of 1090 identified publications, 17 met predefined eligibility criteria. The meta-analysis observed reduced incidence of grade 3/4 overall toxicity (Risk Ratio [RR] 0.32 [95% Cl 0.27-0.39], p < 0.00001) and grade 3/4 diarrhoea (RR 0.38 [95% Cl 0.24-0.61], p < 0.0001) among PGD versus non-PGD cohorts. Within PGD cohorts, there was no statistical differences for overall response rates (complete/partial) (RR 1.31 [95% Cl 0.93-1.85], p = 0.12). Similar results were found with stable disease (RR 1.27 [95% Cl 0.66-2.44], p = 0.47).

CONCLUSION

PGD improves patient outcomes in terms of grade 3/4 toxicity, in particular overall toxicity and diarrhoea, without impacting on treatment response.

REGISTRATION NUMBER

The study is registered with PROSPERO, registration number CRD42020223768.

Dihydropyrimidine Dehydrogenase Deficiency and Implementation of Upfront DPYD Genotyping

Fluoropyrimidines (FP; 5-fluorouracil, capecitabine, and tegafur) are a commonly prescribed class of antimetabolite chemotherapies, used for various solid organ malignancies in over 2 million patients globally per annum. Dihydropyrimidine dehydrogenase (DPD), encoded by the DPYD gene, is the critical enzyme implicated in FP metabolism. DPYD variant genotypes can result in decreased DPD production, leading to the development of severe toxicities resulting in hospitalization, intensive care admission, and even death. Management of toxicity incurs financial burden on both patients and healthcare systems alike. Upfront DPYD genotyping to identify variant carriers allows an opportunity to identify patients who are at high risk to suffer from serious toxicities and allow prospective dose adjustment of FP treatment. This approach has been shown to reduce patient morbidity, as well as improve the cost-effectiveness of managing FP treatment. Upfront DPYD genotyping has been recently endorsed by several countries in Europe and the United Kingdom. This review summarizes current knowledge about DPD deficiency and upfront DPYD genotyping, including clinical and cost-effectiveness outcomes, with the intent of supporting implementation of an upfront DPYD genotyping service with individualized dose-personalization.

An Analysis of Tolerance and Early Survival Outcomes with Perioperative Modified FLOT in Gastric Cancers

Purpose Perioperative chemotherapy with fluorouracil plus leucovorin, oxaliplatin, and docetaxel (FLOT) is a current standard of care for locoregionally advanced gastric adenocarcinomas. There is limited real world data with regard to the tolerance and efficacy of this regimen.

Materials and Methods This is a retrospective analysis of gastric cancer patients who were offered neoadjuvant perioperative modified FLOT regimen between December 2016 and October 2018, at the Tata Memorial Hospital, Mumbai. Chemotherapy-related side-effects are reported along with overall survival (OS), as calculated by Kaplan-Meier method.

Results Three hundred and forty-three consecutive patients were started on neoadjuvant chemotherapy (NACT) with mFLOT of which 298 patients (87%) completed the planned treatment. A total of 294 patients (86%) underwent curative resection of gastric cancer. Common grade 3 and grade 4 toxicities during NACT were diarrhea in 42 patients (12%) and febrile neutropenia in 27 patients (8%). Toxic death was seen in nine (2.6%) patients. A total of 264 patients (77%) completed planned adjuvant chemotherapy. Common grade 3 and grade 4 toxicities during adjuvant therapy were diarrhea in 42 patients (12%) and febrile neutropenia in 16 patients (6%). With a median follow-up of 19 months, the estimated 2-year median OS was 69.4%.

Conclusion Administration of modified FLOT regimen in locoregionally advanced gastric cancers is feasible in clinical practice with high completion rates, though requiring dose modifications due to the incidence of clinically relevant grade 3 to 5 toxicities. Early outcomes with the regimen are on par with survivals from the FLOT-AIO study.

Ethnic Diversity of DPD Activity and the DPYD Gene: Review of the Literature

Pharmacogenomic screening can identify patients with gene variants that predispose them to the development of severe toxicity from fluoropyrimidine (FP) chemotherapy. Deficiency of the critical metabolic enzyme dihydropyrimidine dehydrogenase (DPD) leads to excessive toxicity on exposure to fluoropyrimidine chemotherapy. This can result in hospitalisation, intensive care admissions and even death. Upfront screening of the gene that encodes for DPD (DPYD) has recently been implemented in regions throughout Europe and the United Kingdom. Current screening evaluates DPYD variants that are well described within Caucasian patient populations and provides genotyped-guided dose adjustment recommendations based upon the presence of these variants. This article reviews the differences in DPYD gene variants within non-Caucasian populations compared to Caucasian populations, with regard to the implications for clinical tolerance of fluoropyrimidine chemotherapies and genotype guided dose adjustment guidelines.

Prospective Phase II Open-Label Randomized Controlled Trial to Compare Mandibular Preservation in Upfront Surgery With Neoadjuvant Chemotherapy Followed by Surgery in Operable Oral Cavity Cancer

PURPOSE

The objective of this study was to explore the potential role and safety of neoadjuvant chemotherapy (NACT) in tumor shrinkage and resultant mandibular preservation in oral cancers compared with conventional surgical treatment.

METHODS

This study was a single-center, randomized, phase II trial of treatment-naive histologically confirmed squamous cell carcinoma of the oral cavity with cT2-T4 and N0/N+, M0 (American Joint Committee on Cancer, seventh edition) stage, necessitating resection of the mandible for paramandibular disease in the absence of clinicoradiologic evidence of bone erosion. The patients were randomly assigned (1:1) to either upfront surgery (segmental resection) followed by adjuvant treatment (standard arm [SA]) or two cycles of NACT (docetaxel, cisplatin, and fluorouracil) at 3-week intervals (intervention arm [IA]), followed by surgery dictated by postchemotherapy disease extent. All patients in the IA received adjuvant chemoradiotherapy, and patients in the SA were treated as per final histopathology report. The primary end point was mandible preservation rate. The secondary end points were disease-free survival and treatment-related toxicity.

RESULTS

Sixty-eight patients were enrolled over 3 years and randomly assigned to either SA (34 patients) or IA (34 patients). The median follow-up was 3.6 years (interquartile range 0.95-7.05 years). Mandibular preservation was achieved in 16 of 34 patients (47% [95% CI, 31.49 to 63.24]) in the IA. The disease-free survival (P = .715, hazard ratio 0.911 [95% CI, 0.516 to 1.607]) and overall survival (P = .747, hazard ratio 0.899 [95% CI, 0.510 to 1.587]) were similar in both the arms. Complications were similar in both arms, but chemotherapy-induced toxicity was observed in the majority of patients (grade III: 14, 41.2%; grade IV: 11, 32.4%) in the IA.

CONCLUSION

NACT plays a potential role in mandibular preservation in oral cancers with acceptable toxicities and no compromise in survival. However, this needs to be validated in a larger phase III randomized trial.

Pharmacogenetic profiling of dihydropyrimidine dehydrogenase (DPYD) variants in the Indian population

BACKGROUND

The present study aimed to delineate the pharmacologically relevant dihydropyrimidine dehydrogenase (DPYD) variants in the Indian population.

METHODS

We screened 2000 Indian subjects for DPYD variants using the Infinium Global Screening Array (GSA) (Illumina Inc., San Diego, CA, USA).

RESULTS

The GSA analysis identified seven coding, two intronic and three synonymous DPYD variants. Level 1A alleles (rs75017182, rs3918290, P633Qfs*5 and D949V) were found to be rare (minor allele frequency: 1.889%), whereas Level 3 alleles were observed to be predominant (C29R: 24.91%, I543V: 9.047%, M166V: 8.993% and V732I: 8.44%). In silico predictions revealed that all Level 1A alleles were deleterious, whereas three (M166V, S534N and V732I) of seven Level 3 alleles were damaging. CUPSAT analysis revealed that two Level 1A (P633Qfs*, D949V) and three Level 3 (I543V, V732I and S534N) variants were thermolabile. The pooled Indian data showed that V732I, S534N and rs3918290 variants were associated with 5-FU/capecitabine toxicity, whereas C29R, I543V and M166V variants exhibited the null association. A comparison of our data with other population data from the 'Allele Frequency Aggregator' (https://www.ncbi.nlm.nih.gov/snp/docs/gsr/alfa/) database showed similarities with the South Asian data.

CONCLUSIONS

We have identified four Level 1A (non-functional/dysfunctional) and seven Level 3 variants in the DPYD gene. The pooled Indian data revealed the association of V732I, S534N and rs3918290 variants with 5-FU/capecitabine toxicity. Clustering analysis revealed the similarities in the DPYD profiles of the Indian and South Asian populations.

Effect of a Structured Teaching Module Including Intensive Prophylactic Measures on Reducing the Incidence of Capecitabine-Induced Hand-Foot Syndrome: Results of a Prospective Randomized Phase III Study

LESSONS LEARNED

A structured teaching module including intensive prophylactic measures to alleviate hand-foot syndrome (HFS) during capecitabine therapy is feasible but ineffective at protecting patients from HFS. Pharmacologic therapeutic interventions should be investigated for the management of this complication.

BACKGROUND

Capecitabine-induced hand-foot syndrome (HFS) has a detrimental effect on quality of life. The effect of a structured teaching module including intensive prophylactic measures was evaluated.

METHODS

This non-crossover phase III double-blinded clinical trial randomized patients in a 1:1 ratio to either a control group or to a group administered a structured teaching model including intensive prophylactic measures on HFS administered by a trained oncology nurse at regular intervals (case) versus standard information on HFS care administered by treating clinician (control). The primary endpoint was comparison of fraction of patients in both arms developing at least grade 2 HFS.

RESULTS

Between June 15, 2016, and April 4, 2018, 280 patients (140 to case and 140 to control) were enrolled. The median number of capecitabine chemotherapy cycles was eight; 269 patients (96%) were evaluable for HFS, of whom 89 patients (33.08%) developed at least grade 2 HFS (grade 2 HFS, 73 patients [26.1%]; grade 3 HFS, 16 patients (5.7%}). There was no difference in at least grade 2 HFS between evaluable case and control arms of the study (control group, 45/135 [33.3%]; case, 44/134 [32.8%]; p = .93).

CONCLUSION

The use of a structured teaching module including intensive prophylactic measures was feasible, but this did not reduce the incidence and severity of capecitabine-induced HFS.