Abstract P4-14-08: Serum concentrations of tamoxifen and Z-endoxifen may predict sexual dysfunction in the 2nd year of adjuvant endocrine treatment

Background and rationale: Side effects of adjuvant treatment with tamoxifen (tam) may impair Quality of Life (QoL) and have been suggested as an independent variable for discontinuation of tam1. There are large inter-patient variabilities in prevalence and severance of side effects among tam users. Therefore, there is a need for biological markers that can predict side effects. A potential biological predictor is the serum concentrations of tam and/or its metabolites. In this prospective observational study we have analyzed serum concentrations of tam and 9 metabolites over 3 years. Patients Reported Outcome Measures (PROM) were obtained to elucidate possible associations between side effects, adherence and tam metabolism.

Methods: Breast cancer patients using adjuvant tam (20mg/d) were recruited through the Prospective Breast Cancer Biobank project between 2011 and 2016. Inclusion criteria were ER positive status, ≥ 6 months tam use, tumor size of ≥0.1 cm and being able to read and write Norwegian. Concentration levels of tam and metabolites in serum were analyzed by LC-MS/MS2 and adherence data were collected through the Norwegian prescription database. PROM-data comprised of validated questioners reporting side effects of endocrine treatment and QoL. Statistical analyses comprised non-parametric tests, logistic regression, chi square tests and the Benjamin-Hochberg procedure to correct for multiple testing.

Results: Associations between metabolite concentrations and side effects were run as a cross sectional analysis (N=149) and separate analysis of each year of follow-up with 85, 77 and 65 patients at the 1st, 2nd and 3rd year respectively. We found that 78 % of patients reported side effects, 66 % reported mood swings, 21 % reported severe hot flushes and 71 % reported decreased libido. When analyzing years separately, we found that on the 2nd year patients experiencing vaginal dryness had significantly higher levels of tamoxifen (P=0.032, after correction for multiple testing and adjustment for clinical relevant variables) compared to patients not experiencing vaginal dryness. Also, on year 2 the patients in the lower quartile of Z-endoxifen (≤17.9 nM) had significantly lower libido (p=0.015) compared to patients with Z-endoxifen levels >17.9 nM after adjustment for clinical relevant variables and correction for multiple testing. Analyses regarding adherence are not complete and more results will be presented in the poster.

Discussion: Our data indicates that high serum concentrations of tam and low concentrations of Z-endoxifen are associated with vaginal dryness and sexual dysfunction. Patients reporting “very low libido” had the highest levels of tam, suggesting that slow metabolic conversion and accumulation of tam may contribute to sexual dysfunction. Our results were only significant in the second year of follow-up, possibly because patients wait to resume sexual activity after diagnosis, chemo and surgery. After receiving advice (i.e. lubricants), the symptoms are often reduced in the subsequent follow-up (3rd year). In conclusion, our results indicate that monitoring tam serum concentrations may be used to predict side effects.

1 Owusu C. et al. JCO. 2008

2 Helland T. et al. BCR. 2017

Citation Format: Helland T, Haugstøyl ME, Hagen KB, Kvaløy JT, Lunde S, Lode K, Lind RA, Gripsrud BH, Bifulco E, Gebreslase NS, Jonassen J, Hustad SS, Aas T, Lende TH, Lien EA, Janssen EA, Mellgren G, Søiland H. Serum concentrations of tamoxifen and Z-endoxifen may predict sexual dysfunction in the 2nd year of adjuvant endocrine treatment [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-14-08.

Abstract P3-12-05: Serum levels of the active tamoxifen metabolite Z-4OHtam is predictive of long-term survival in luminal B subtype of breast cancer patients

Background

Tamoxifen (tam) is the main adjuvant endocrine treatment option in premenopausal breast cancer (BC) patients comprising luminal-like tumors. However, a significant proportion of tam-users will experience a relapse within 15 years of primary surgery. We postulate that some patients do not achieve the full clinical benefit of tam due to inter-individual differences in the metabolism of the drug and that the clinical relevance of this may be different between molecular subtypes of BC. Here, we have compared the prognostic value of threshold levels of active tam metabolites in PAM50 luminal (lum) A and B molecular subtypes.

Material and Methods

A number of 64 lum-like BC patients who were relapse-free 3 years after surgery, were retrospectively analyzed in the observational Oslo1 study. All patients received 20 mg tamoxifen daily for 5 years. Serum was obtained at the time of the 3 years follow-up. A sensitive and accurate LC-MS/MS method was developed and validated for the detection and quantification of tam and 9 metabolites in human serum. The median follow-up time from serum sampling to BC death or last follow-up was 13.9 years (0.6-16.5). Recurrence score and molecular subtype of the patients were determined on FFPE-tumor samples using the PAM50 classification algorithm.

Results

A linear trend was identified for the correlation between active metabolite Z-4OHtam and BCSS (p=0.021, HR=0.64, CI95=0.43–0.93). There was no linear association between the remaining metabolites and BC outcome. We further explored the possible association between survival and concentration thresholds for the active metabolites Z-4OHtam and Z-endoxifen and identified supervised cut off values representing low concentrations for Z-4OHtam (≤3.26 nM) and Z-endoxifen (≤9.00 nM). BC patients with low Z-4OHtam had a BCSS of 33.3% compared to 82.8% in patients with Z-4OHtam >3.26 nM (p<0.001, logrank; HR=6.83, CI 95=2.09-22.36). Lum status (A vs B; HR=5.50, CI95= 1.66-18.25) and Z-4OHtam concentration status (high vs low; HR=6.05, CI95=1.74-21.06) were the only factors left in the final multivariable model. A log-linear relationship between the ROR score and BCSS (p=0.002, HR=1.09, CI95=1.03–1.15) was identified after adjustment of clinically relevant variables and lum status was highly prognostic, (Lum A vs B; p=0.001, HR=5.2, CI=1.72-15.46). Therefore, we wanted to compare the prognostic value of the Z-4OHtam threshold in patients subgroups stratified by lum status. Low concentrations of Z-4OHtam were associated with poorer survival for patients in the lum B group only (HR=4.94, CI 95=1.16-21-02). For the lum A patients no significant association was found.

Discussion

Low levels (≤ 3.26 nM) of the active tam metabolite Z-4OHtam was associated with a poorer long-term outcome in tam-treated BC patients. However, when grouping patients according to the PAM50-based molecular subtype, this was only significant in patients belonging to the lum B subtype. Our results suggest that higher levels of active tam metabolites and thus better ER blockage are more important in the more aggressive lum B subtype.

Citation Format: Helland T, Søiland H, Hustad S, Lash TL, Kvaløy JT, Renolen A, Borgen E, Bifulco E, Henne N, Lien EA, Mellgren G, Naume B, Janssen EA. Serum levels of the active tamoxifen metabolite Z-4OHtam is predictive of long-term survival in luminal B subtype of breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-12-05.

Abstract P2-09-11: Metabolite-guided long-term prediction of outcome in tamoxifen treated breast cancer patients

Background

The genetic polymorphisms of CYP2D6 determine its enzymatic activity thereby the pharmacokinetic velocity by which tamoxifen (tam) is converted into active metabolites. Combined analyses of tam metabolites compared to CYP2D6 type and long-term survival could allow prediction of tam response and personalization of therapies. The clinical importance of defining such subgroups in the era of the new long-term (10-year) tam treatment paradigm is actualized.

Material and Methods

From May 1995 to December 1998, patients were included in an observational micro-metastasis study in the Oslo region and treated according to the national guidelines at the time (1). Serum samples were drawn at 3-year follow-up from 356 relapse-free patients, 106 of these were treated with tamoxifen. The median follow up time for breast cancer death was 16.8 years (3.5-19.4).

Serum samples were processed using protein precipitation with acetonitrile. An Aquity UPLC system was used to chromatographically separate 10 tam metabolites using a BEH C18 Phenyl column (100 x 2.1 mm, 1.7 μm particle size) that was developed with a water-methanol gradient containing 0.1% formic acid. The LC system was coupled to a Xevo TQ-S tandem mass spectrometer equipped with an atmospheric pressure photoionization source. The method was validated with respect to linearity, imprecision, accuracy, and functional sensitivity according to FDA guidelines.

Results

The new LC-MS/MS method separated the active Z-isomers of 4OHtam and 4OHNDtam (endoxifen) from its inactive Z'-isomers and E-isomers. Imprecision (intra and inter-day CV %) was within 10 % for target concentrations for all metabolites and accuracies were in the range 95-106%. The method was validated with serum samples from 42 breast cancer patients using 20 mg of tamoxifen.

The endoxifen concentrations ranged from 0 to 90 nM, with a median value of 25 nM. The previous observed endoxifen level of 10 nM in poor metabolizers (2) was used as cut-off for the grouping of patients. The nil endoxifen (NE) group (< 0.1nM, n=14) or low-endoxifene (LE) group (0.1-10 nM, n=8) were grouped together. Univariate survival analysis did not show a significant association between breast cancer specific survival and endoxifen levels. (p=0.15; logrank and p=0.18;Breslow). However, for the period beyond 10-years of follow-up the breast cancer survival differed between the high endoxifene (HE) group and the NE+LE groups. For patients surviving the first 10 years the breast cancer specific survival was 94.2% vs. 77.8% for the HE and NE+LE groups respectively (p=0.020, logrank and p=0.017, Breslow, HR=4.5, CI 95=1.1-17.9). In the multivariate analysis endoxifen ≤/> 10 nM remained the only factor in the final model.

Discussion

We developed a new accurate and precise LC-MS/MS method for the measurement of 10 tamoxifen metabolites. Importantly, the method separates active and inactive isomers of 4OHtam and 4OHNDtam/endoxifen. Despite the low number of patients, we observed a poorer long-term survival beyond 10 years in patients with nil or low serum concentration of endoxifen. A comprehensive analysis is presented addressing the relationship between genotyped based and metabolite based prediction of long-term outcome in tamoxifen treated breast cancer patients.

Ref:

1. Wiedswang G, et al. Clin Ca Res; 2004

2. Mürdter TE, et al. Clin Pharmacol Ther; 2011.

Citation Format: Helland T, Henne N, Bifulco E, Hustad SS, Kristensen VN, Lash T, Borgen E, Janssen EAM, Lien EA, Naume B, Mellgren G, Søiland H. Metabolite-guided long-term prediction of outcome in tamoxifen treated breast cancer patients [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-09-11.

Homocysteine and its relation to B-vitamins in Graves' disease before and after treatment: effect modification by smoking

OBJECTIVES

To investigate plasma total homocysteine levels and its relation to B-vitamins and smoking in Graves' disease before and after antithyroid therapy.

DESIGN

A longitudinal study taking place at four hospitals in Norway.

METHODS AND SUBJECTS

Plasma total homocysteine, serum folate, serum cobalamin and riboflavin, flavin mononucleotide and flavin adenine dinucleotide in plasma were investigated in 182 patients with hyperthyroidism before treatment. The same parameters were reinvestigated in 112 of these patients after attaining euthyroid state.

RESULTS

In hyperthyroidism, plasma total homocysteine was low, and inversely related to folate, cobalamin and riboflavin, and positively related to serum creatinine and age. Following antithyroid therapy, total homocysteine increased and the concentration of folate, cobalamin, riboflavin, flavin mononucleotide and flavin adenine dinucleotide decreased significantly. The most pronounced reduction (35%) was observed for flavin mononucleotide. In the hyperthyroid state, smokers had lower levels of folate and flavin mononucleotide than non-smokers. After restoration of euthyroidism, both folate and riboflavin were significantly lower in smokers than non-smokers. Plasma total homocysteine increased according to decreasing quartiles of B-vitamins. For riboflavin, this relation was confined to smokers.

CONCLUSION

Plasma total homocysteine changes according to thyroid status. These changes may be partly attributable to altered folate, cobalamin but also riboflavin status, particularly in smokers.

Biological and clinical implications of the MTHFR C677T polymorphism

The enzyme methylenetetrahydrofolate reductase (MTHFR) directs folate species either to DNA synthesis or to homocysteine (Hcy) remethylation. The common MTHFR C677T polymorphism affects the activity of the enzyme and hence folate distribution. Under conditions of impaired folate status, the homozygous TT genotype has been regarded as harmful because it is associated with a high concentration of plasma total Hcy, increased risk of neural tube defects and colorectal neoplasias, and can also predispose individuals to adverse effects from drugs with antifolate effects. The MTHFR C677T polymorphism shows no consistent correlation with cardiovascular risk and longevity but, in combination with positive folate balance, the TT genotype is associated with decreased risk of colorectal neoplasias. Because of the high prevalence of this polymorphism in most populations, the TT variant might represent an ancestral genetic adaptation to living constraints (tissue injury or unbalanced vitamin intake) that has become a determinant of disease profiles in modern times.

Riboflavin as a determinant of plasma total homocysteine: effect modification by the methylenetetrahydrofolate reductase C677T polymorphism

BACKGROUND

Plasma total homocysteine (tHcy) is a risk factor for cardiovascular disease. tHcy concentrations are partly determined by folate, cobalamin, and vitamin B(6) status, and methylenetetrahydrofolate reductase (MTHFR) and other flavoenzymes are important for the biotransformation of these vitamins. This motivates the investigation of the possible relationship between riboflavin status and tHcy.

METHODS

The study had a cross-sectional design and included 423 healthy blood donors, ages 19-69 years. We determined plasma tHcy, serum folate, serum cobalamin, serum creatinine, and MTHFR C677T genotype. In addition, we measured riboflavin and its two coenzyme forms, flavin mononucleotide and flavin adenine dinucleotide, in EDTA plasma by capillary electrophoresis and laser-induced fluorescence detection.

RESULTS

Riboflavin determined tHcy independently in a multiple linear regression model with adjustment for sex, age, folate, cobalamin, creatinine, and MTHFR genotype (P = 0.008). tHcy was 1.4 micromol/L higher in the lowest compared with the highest riboflavin quartile. The riboflavin-tHcy relationship was modified by genotype (P = 0.004) and was essentially confined to subjects with the C677T transition of the MTHFR gene.

CONCLUSIONS

Plasma riboflavin is an independent determinant of plasma tHcy. Studies on deficient populations are needed to evaluate the utility of riboflavin supplementation in hyperhomocysteinemia.

Quantification of riboflavin, flavin mononucleotide, and flavin adenine dinucleotide in human plasma by capillary electrophoresis and laser-induced fluorescence detection

BACKGROUND

Riboflavin is the precursor of flavin mononucleotide (FMN) and FAD, which serve as cofactors for several redox enzymes. We have developed a capillary electrophoresis method for the determination of riboflavin and its two coenzyme forms in human plasma.

METHODS

Trichloroacetic acid-treated plasma was subjected to solid-phase extraction on reversed-phase columns. The analytes were separated by micellar electrokinetic capillary chromatography in uncoated fused- silica capillaries filled with borate buffer containing 50 mmol/L sodium dodecyl sulfate, methanol, and N-methylformamide. Native fluorescence was monitored at 530 nm, using an argon laser operating at 488 nm as excitation source.

RESULTS

The assay was linear over a concentration range of two orders of magnitude, and the limit of detection was far below physiological concentrations for all vitamers. The within-day and between-day coefficients of variation were 4-9% and 6-12%, respectively. The reference values (median, 5-95 percentiles) obtained by analyzing plasma from 63 healthy subjects were 8.6 nmol/L (2.7-42.5 nmol/L) for riboflavin, 7.0 nmol/L (3.5-13.3 nmol/L) for FMN, and 57.9 nmol/L (44.5-78.1 nmol/L) for FAD.

CONCLUSIONS

Capillary electrophoresis with laser-induced fluorescence detection allows determination of all riboflavin vitamers far below physiological concentrations. The method may become a useful tool for the assessment of riboflavin status in humans.

[Cerebral air embolism after percutaneous lung puncture]

Cerebral air embolism is a rare but serious complication to percutaneous transthoracic fine needle aspiration of the lung. A case is described after puncture of a tumour in the right lung with a 0.6 mm needle. The patient developed paralysis of the upper and lower extremities on his left side, probably due to an air embolism in the right middle cerebral artery. He was fully restituted after early hyperbaric treatment with oxygen.