Abstract 3425
Background
Genetic variants of dihydropyrimidine dehydrogenase (DPYD) gene can result in varied enzymatic activity and potential toxicity when receiving 5-FU chemotherapy including treatment related death in up to 1% patients. Current international guidelines suggest an international rate of 3-5% albeit routine prospective pharmacogenomic testing is not currently recommended. However, in a genetically homogenous population such as Ireland, DPYD variant enrichment may support routine testing.
Methods
All patients receiving 5-FU based chemotherapy in South & South-West region of Ireland were prospectively tested from 01/09/2018 to present. The Viapath DPYD genotyping panel which interrogates for 5 variants was used. Toxicity type and grade for all patients were recorded (CTCAE v5.0).
Results
To date, 139 patients have been tested,50.4% male and 49.6% female, median age 63 years. The majority(59%) were being treated for colorectal cancer. Sixteen patients were found to be heterozygous carriers of a DYPD variant with one compound heterozygous variant identified i.e. an overall prevalence of 12 %. No homozygous carriers were identified. Grade ≥3 was observed in 33% DPYD variant carriers compared to 19% in DPYD wild type patients i.e. relative risk of grade ≥3 toxicity is 1.7, p = 0.17.Table:
648P
DPYD Variants | Prevalence % n = 139 | % Rate of ≥ G3 toxicity |
---|---|---|
7(5.0%) | 42% | |
c. 2846A>T | 1(0.7%) | n/a* |
c. 1905 + 1G>A | 3(2.2%) | 100% |
c. 1679T>G | 0 (0%) | n/a* |
c. 1601GA | 5 (3.6%) | 0% |
c. 1905 + 1G>A+c;1236G>A/Hapb3 compound heterozygous | 1(0.7%) | n/a* |
TOTAL:17 (12.2%) |
Conclusions
The study shows a higher than expected prevalence of DPYD variants of 12.2% compared to internationally reported 3-5%. Patients with DPYD variants c.1236G>A and c.1905+1G>A were particularly likely to develop Grade ≥ 3 toxicity. Prospective testing continues to assess the clinical relevance of individual variants in our population.
Legal entity responsible for the study: The authors.
Clinical trial identification
Editorial acknowledgement
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
3536 - Palbociclib plus an aromatase inhibitor as first-line therapy for metastatic breast cancer in US clinical practices: Real-world progression-free survival analysis
Presenter: Mylin Torres
Session: Poster Display session 2
Resources:
Abstract
4022 - Ribociclib (RIB) plus letrozole (LET) in male patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor-2–negative (HER2–) advanced breast cancer (ABC) from the CompLEEment-1 trial
Presenter: Mario Campone
Session: Poster Display session 2
Resources:
Abstract
3599 - Comparative effectiveness of palbociclib plus letrozole vs letrozole for metastatic breast cancer in US real-world clinical practices
Presenter: Rachel Layman
Session: Poster Display session 2
Resources:
Abstract
901 - Pharmacokinetics (PK), safety, and efficacy of [fam-] trastuzumab deruxtecan with OATP1B/CYP3A inhibitors in subjects with HER2-expressing advanced solid tumors
Presenter: Yung-Jue Bang
Session: Poster Display session 2
Resources:
Abstract
2777 - A Phase 2 study of abemaciclib in patients (pts) with brain metastases (BM) secondary to non-small cell lung cancer (NSCLC) or melanoma (MEL).
Presenter: Solmaz Sahebjam
Session: Poster Display session 2
Resources:
Abstract
3980 - Ribociclib (RIB) + letrozole (LET) in patients (pts) with visceral metastases (VM) or bone-only metastases (BOM) in hormone receptor-positive (HR+), human epidermal growth factor receptor-2–negative (HER2–) advanced breast cancer (ABC): Subgroup analysis from the CompLEEment-1 trial
Presenter: Michelino De Laurentiis
Session: Poster Display session 2
Resources:
Abstract
4024 - Ribociclib (RIB) + letrozole (LET) in patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor-2–negative (HER2–) advanced breast cancer (ABC) and central nervous system (CNS) metastases: Subgroup analysis from the phase 3b CompLEEment-1 trial
Presenter: Paul Cottu
Session: Poster Display session 2
Resources:
Abstract
2151 - Clinical outcome and toxicity data in patients with advanced breast cancer treated with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors combined with endocrine therapy in a real-world clinical setting.
Presenter: Elena Fountzilas
Session: Poster Display session 2
Resources:
Abstract
3994 - Safety and efficacy of Ribociclib (RIBO) + letrozole (LET) in patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (ABC): Interim results from the Italian cohort of the CompLEEment-1 (C-1) study.
Presenter: Michele De Laurentiis
Session: Poster Display session 2
Resources:
Abstract
1370 - Interim Results From CompLEEment-1 (A Phase 3b Study of Ribociclib and Letrozole as First-Line Therapy for Advanced Breast Cancer in an Expanded Population): Spanish cohort results
Presenter: Javier Salvador
Session: Poster Display session 2
Resources:
Abstract