Population Pharmacokinetics of Intracellular 5-Fluorouridine 5'-Triphosphate and its Relationship with Hand-and-Foot Syndrome in Patients Treated with Capecitabine

Capecitabine-induced hand-foot syndrome: A pharmacogenetic study beyond DPYD

AIM OF THE STUDY

Occurrence of hand-foot syndrome (HFS) during capecitabine treatment often results in treatment interruptions (26 %) or treatment discontinuation (17 %), and can severely decrease quality of life. In this study, we investigated whether single nucleotide polymorphisms (SNPs) in genes involved in capecitabine metabolism - other than DPYD - are associated with an increased risk for capecitabine-induced HFS.

METHODS

Patients treated with capecitabine according to standard of care were enrolled after providing written informed consent for genotyping purposes. Prospectively collected blood samples were used to extract genomic DNA, which was subsequently genotyped for SNPs in CES1, CES2 and CDA. SNPs and clinical baseline factors that were univariably associated with HFS with P ≤ 0.10, were tested in a multivariable model using logistic regression.

RESULTS

Of the 446 patients eligible for analysis, 146 (32.7 %) developed HFS, of whom 77 patients (17.3 %) experienced HFS ≥ grade 2. In the multivariable model, CES1 1165-33 C>A (rs2244613, minor allele frequency 19 %) and CDA 266 + 242 A>G (rs10916825, minor allele frequency 35 %) variant allele carriers were at higher risk of HFS ≥ grade 2 (OR 1.888; 95 %CI 1.075-3.315; P = 0.027 and OR 1.865; 95 %CI 1.087-3.200; P = 0.024, respectively).

CONCLUSIONS

We showed that CES1 1165-33 C>A and CDA 266 + 242 A>G are significantly associated with HFS grade 2 and grade 3 in patients treated with capecitabine. Prospective studies should assess whether this increased risk can be mitigated in carriers of these SNPs, when pre-emptive genotyping is being followed by dose adjustment or by alternative treatment by a fluoropyrimidine that is not substrate to CES1, such as S1.

Efficacy of temozolomide combined with capecitabine (CAPTEM) on refractory prolactinomas as assessed using an ex vivo 3D spheroid assay

PURPOSE

Refractory prolactinomas resistant to dopamine agonists (DAs) pose a clinical challenge. Temozolomide (TMZ) is a recommended treatment option, but its effects are difficult to predict, and the alternatives are limited. Recent reports suggested that TMZ combined with capecitabine (CAPTEM) can be effective for the treatment of aggressive pituitary tumors. This study sought to evaluate the effect of TMZ in an ex vivo three-dimensional (3D) spheroid culture assay and determine if this assay could be used to predict the therapeutic effect of CAPTEM in actual refractory prolactinomas.

METHODS

Surgically resected tumor tissues from two patients with refractory prolactinoma were cultured as 3D spheroids. The effects of TMZ were assessed based on its suppression of cell viability and reduction of prolactin (PRL) levels.

RESULTS

In Case 1, the 3D culture assay showed no effect of TMZ on cell viability or PRL suppression. Clinically, TMZ treatment did not reduce PRL levels (8870→8274 ng/mL) and the tumor progression. However, CAPTEM partially reduced PRL levels (9070→4046 ng/mL) and suppressed the tumor growth. In Case 2, TMZ in the 3D culture assay showed a 50% reduction of cell viability and 40% reduction of PRL levels. Clinically, CAPTEM was highly effective, with a considerable reduction in PRL level (17,500→210 ng/mL), and MRI showed almost no residual tumor.

CONCLUSIONS

This is the first report to describe the effects of CAPTEM treatment on refractory prolactinomas. The ex vivo 3D spheroid culture assay reliably predicted TMZ sensitivity and informed the selection between TMZ or CAPTEM treatment for refractory prolactinomas.