Tamoxifen Metabolism and Efficacy in Breast Cancer: A Prospective Multicenter Trial

Purpose: Levels of endoxifen, the most active metabolite of tamoxifen, vary by the highly polymorphic cytochrome P450 (CYP) 2D6 enzyme. We prospectively investigated tamoxifen efficacy by serum endoxifen levels and the tamoxifen activity score (TAS).Experimental Design: A prospective observational multicenter study included postmenopausal women with an estrogen receptor-positive breast cancer receiving first-line tamoxifen, 20 mg daily in the neoadjuvant or metastatic setting, recruited between February 2009 and May 2014. The primary endpoint was the objective response rate (ORR) using RECIST criteria 1.0. Secondary endpoints were clinical benefit (CB), progression-free survival (PFS), and tolerability of tamoxifen. The main analysis used logistic regression to relate ORR to serum endoxifen levels after 3 months. Endpoints were also related to other tamoxifen metabolites and to TAS.Results: Endoxifen levels were available for 247 of all 297 patients (83%), of which 209 with target lesions (85%). Median follow-up time for PFS was 32.5 months, and 62% progressed. ORR and CB were 45% and 84%, respectively. ORR was not related to endoxifen, and the OR of ORR was 1.008 per μg/L increase in endoxifen (95% confidence interval, 0.971-1.046; P = 0.56). In general, none of the endpoints was associated with endoxifen levels, tamoxifen metabolites, or TAS.Conclusions: Under the prespecified assumptions, the results from this prospective clinical trial do not suggest therapeutic drug monitoring of endoxifen to be of clinical value in postmenopausal women treated with tamoxifen for breast cancer in the neoadjuvant or metastatic setting. Clin Cancer Res; 24(10); 2312-8. ©2018 AACR.

Clinical and genetic risk factors for epirubicin-induced cardiac toxicity in early breast cancer patients

Anthracycline-induced cardiotoxicity (ACT) is a well-known serious adverse drug reaction leading to substantial morbidity. The purpose of this study was to assess ACT occurrence and clinical and genetic risk factors in early breast cancer patients. In 6 genes of interest (ABCC1, ABCC2, CYBA, NCF4, RAC2, SLC28A3), 10 single nucleotide polymorphisms (SNPs) involved in ACT were selected based on a literature search. Eight hundred and seventy-seven patients treated between 2000 and 2010 with 3-6 cycles of (neo) adjuvant 5-fluorouracil, epirubicin and cyclophosphamide (FEC) were genotyped for these SNPs using Sequenom MassARRAY. Main outcome measures were asymptomatic decrease of left ventricular ejection fraction (LVEF) > 10 % and cardiac failure grade 3-5 (CTCAE 4.0). To evaluate the impact of these 10 SNPs as well as clinical factors (age, relative dose intensity of epirubicin, left-sided radiotherapy, occurrence of febrile neutropenia, and planned and received cycles of epirubicin) on decrease of LVEF and cardiac failure, we performed uni- and multivariable logistic regression analysis. Additionally, exploratory analyses including 11 additional SNPs related to the metabolism of anthracyclines were performed. After a median follow-up of 3.62 years (range 0.40-9.60), a LVEF decline of > 10 % occurred in 153 patients (17.5 %) and cardiac failure in 16 patients (1.8 %). In multivariable analysis, six cycles of FEC compared to three cycles received and heterozygous carriers of the rs246221 T-allele in ABCC1 relative to homozygous carriers of the T-allele were significantly associated with LVEF decline of > 10 % (OR 1.3, 95 % CI 1.1-1.4, p < 0.001 and OR 1.6, 95 % CI 1.1-2.3, p = 0.02). Radiotherapy for left-sided breast cancer was associated with cardiac failure (OR 3.7, 95 % CI 1.2-11.5, p 0.026). The other 9 SNPs and clinical factors tested were not significantly associated. In our exploratory analysis, no other SNPs related to anthracycline metabolism were retained in the multivariate model for prediction of LVEF decline. ACT in breast cancer patients is related to number of received cycles of epirubicin and left-sided radiotherapy. Additional studies should be performed to independently confirm the potential association between rs246221 in ABCC1 and LVEF.

Abstract OT2-1-05: Prospective multicenter study evaluating the effect of impaired tamoxifen metabolization on efficacy in breast cancer patients receiving tamoxifen in the neo-adjuvant or metastatic setting - The CYPTAM-BRUT 2 trial

Background

Tamoxifen is commonly used to treat and prevent hormone receptor positive breast cancers. This drug is metabolized into more active metabolites by liver enzymes such as cytochrome P450 (CYP) enzymes. Endoxifen is considered to be the principal active metabolite of tamoxifen. As CYP enzymes are highly polymorphic in humans, endoxifen plasma levels are modulated by the patient’s genotype. It, however, is not yet clear if lowered endoxifen plasma levels have an effect on tamoxifen efficacy. This is the first prospective study where the association between endoxifen plasma concentrations, multiple CYP-genotypes and clinical outcome in postmenopausal patients treated with tamoxifen is investigated.

Trial Design

CYPTAM-BRUT 2 is a prospective multi-center open label, single-arm, non-randomized observational study. Postmenopausal women with measurable, estrogen receptor positive breast cancer receiving tamoxifen as neo-adjuvant or as first-line metastatic treatment are included in this study. The objective treatment response and clinical benefit are observed to investigate the efficacy of 20 mg tamoxifen daily. Patients are allowed to have started tamoxifen before inclusion but not more than three months. Further, if more than twelve months have passed after completion of the adjuvant therapy prior endocrine therapy in the adjuvant setting is allowed. Patients receiving neo-adjuvant tamoxifen will be assessed no more than four months after starting with tamoxifen.

The primary endpoint is a statistical association between steady-state endoxifen plasma concentrations and the objective response rate (ORR) after 3-6 months of tamoxifen, under the assumption that the relationship is linear with an odds ratio (OR) of 1.49 per 10 nmol/L. Using available data on endoxifen concentrations, this OR is chosen to reflect an improvement from 10% ORR in the lowest endoxifen quartile to 30% in the highest endoxifen quartile when the overall ORR is around 18%. To have 90% power at a 5% significance level, 180 patients have to be included into the study. The main secondary study endpoint is the relation between endoxifen plasma concentrations and clinical benefit (CR+PR+SD at 6 months). The study has to include 270 patients to detect a statistically significant association with endoxifen with 90% power at a 5% significance level, assuming an OR of 1.28 per 10 nmol/L. This OR is chosen to reflect an improvement of clinical benefit at 6 months from 30% in the lowest endoxifen quartile to 50% in the highest endoxifen quartile (overall clinical benefit around 39%). For both endpoints the RECIST criteria are used. Other endpoints are progression-free survival, tolerability of tamoxifen treatment and the association between CYP2D6 genotype and clinical outcome.

Patient accrualPatients from 22 participating centers in Belgium and Switzerland are included in this trial. In May 2014, the predefined sample size of 270 patients was reached. Follow-up of the last patients will continue until all required data are obtained (i.e blood samples and response evaluation).

Citation Format: Kathleen Van Asten, Lynn Jongen, Anne-Sophie Dieudonné, Anneleen Lintermans, Chantal Blomme, Olivier Brouckaert, Diether Lambrechts, Hans Wildiers, Marie-Rose Christiaens, Dirk Timmerman, Ben Van Calster, Jan Decloedt, Patrick Berteloot, Didier Verhoeven, Markus Joerger, Khalil Zaman, Vincent Dezentjé, Patrick Neven. Prospective multicenter study evaluating the effect of impaired tamoxifen metabolization on efficacy in breast cancer patients receiving tamoxifen in the neo-adjuvant or metastatic setting - The CYPTAM-BRUT 2 trial [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr OT2-1-05.

Impact of genetic variability and treatment-related factors on outcome in early breast cancer patients receiving (neo-) adjuvant chemotherapy with 5-fluorouracil, epirubicin and cyclophosphamide, and docetaxel

To assess the impact of patient-related factors, including genetic variability in genes involved in the metabolism of chemotherapeutic agents, on breast cancer-specific survival (BCSS) and recurrence-free interval (RFI). We selected early breast cancer patients treated between 2000 and 2010 with 4-6 cycles of (neo-)adjuvant 5-fluorouracil, epirubicin, and cyclophosphamide (FEC) or 3 cycles FEC followed by 3 cycles docetaxel. Tumor stage/subtype; febrile neutropenia and patient-related factors such as selected single nucleotide polymorphisms and baseline laboratory parameters were evaluated. Multivariable Cox regression was performed. Of 991 patients with a mean follow-up of 5.2 years, 152 (15.3 %) patients relapsed and 63 (6.4 %) patients died. Advanced stage and more aggressive subtype were associated with poorer BCSS and RFI in multivariable analysis (p < 0.0001). Associations with worse BCSS in multivariable analysis were: homozygous carriers of the rs1057910 variant C-allele in CYP2C9 (hazard ratio [HR] 30.4; 95 % confidence interval [CI] 6.1-151.5; p < 0.001) and higher white blood cell count (WBC) (HR 1.2; 95 % CI 1.0-1.3; p = 0.014). The GT genotype of the ABCB1 variant rs2032582 was associated with better BCSS (HR 0.5; 95 % CI 0.3-0.9, p = 0.021). Following associations with worse RFI were observed: higher WBC (HR 1.1; 95 % CI 1.0-1.2; p = 0.026), homozygous carriers of the rs1057910 variant C-allele in CYP2C9 (HR 10.9; 95 % CI 2.5-47.9; p = 0.002), CT genotype of the CYBA variant rs4673 (HR 1.8; 95 % CI 1.2-2.7; p = 0.006), and G-allele homozygosity for the UGT2B7 variant rs3924194 (HR 3.4; 95 % CI 1.2-9.7, p = 0.023). Patient-related factors including genetic variability and baseline white blood cell count, impacted on outcome in early breast cancer.

Multivariable regression analysis of febrile neutropenia occurrence in early breast cancer patients receiving chemotherapy assessing patient-related, chemotherapy-related and genetic risk factors

Background

Febrile neutropenia (FN) is common in breast cancer patients undergoing chemotherapy. Risk factors for FN have been reported, but risk models that include genetic variability have yet to be described. This study aimed to evaluate the predictive value of patient-related, chemotherapy-related, and genetic risk factors.

Methods

Data from consecutive breast cancer patients receiving chemotherapy with 4–6 cycles of fluorouracil, epirubicin, and cyclophosphamide (FEC) or three cycles of FEC and docetaxel were retrospectively recorded. Multivariable logistic regression was carried out to assess risk of FN during FEC chemotherapy cycles.

Results

Overall, 166 (16.7%) out of 994 patients developed FN. Significant risk factors for FN in any cycle and the first cycle were lower platelet count (OR = 0.78 [0.65; 0.93]) and haemoglobin (OR = 0.81 [0.67; 0.98]) and homozygous carriers of the rs4148350 variant T-allele (OR = 6.7 [1.04; 43.17]) in MRP1. Other significant factors for FN in any cycle were higher alanine aminotransferase (OR = 1.02 [1.01; 1.03]), carriers of the rs246221 variant C-allele (OR = 2.0 [1.03; 3.86]) in MRP1 and the rs351855 variant C-allele (OR = 2.48 [1.13; 5.44]) in FGFR4. Lower height (OR = 0.62 [0.41; 0.92]) increased risk of FN in the first cycle.

Conclusions

Both established clinical risk factors and genetic factors predicted FN in breast cancer patients. Prediction was improved by adding genetic information but overall remained limited. Internal validity was satisfactory. Further independent validation is required to confirm these findings.

How often did Belgian physicians co-prescribe tamoxifen with strong CYP2D6 inhibitors over the last 6 years?

AIMS

Tamoxifen is widely used in the treatment of breast cancer. It is a pro-drug metabolized to the more active endoxifen through CYP2D6. Concomitant intake of CYP2D6 inhibitors results in lower endoxifen levels and could influence efficacy. The objective of this study was to evaluate the evolution of co-prescription of tamoxifen and CYP2D6 inhibitors in Belgium.

METHODS

Data were retrieved from the Pharmanet database of the National Institute for Health and Disability Insurance for the period January 2006-December 2009. For the analysis of the evolution of the co-prescription, the period was divided in subperiods of 2 months. The category tamoxifen+CYP2D6 inhibitor was defined as women who were delivered tamoxifen and a CYP2D6 inhibitor in that subperiod. The results were validated on the period December 2011-May 2012.

RESULTS

The percentage of co-prescription decreased over time for the strong CYP2D6 inhibitors and increased for the weak CYP2D6 inhibitor, with these trends persisting in 2012. Tamoxifen and CYP2D6 inhibitors were mostly prescribed by general practitioners and gynaecologists and by general practitioners and psychiatrists, respectively.

DISCUSSION

This study shows that a proportion of women taking tamoxifen in Belgium are prescribed a strong CYP2D6 inhibitor, which could affect tamoxifen efficacy. Over time, the concomitant intake decreased. Paroxetine was the most prescribed strong CYP2D6 inhibitor. Venlafaxine, a weak CYP2D6 inhibitor, was prescribed more often. This study also shows that tamoxifen and the CYP2D6 inhibitors are not only prescribed by physicians specialized in breast cancer; therefore, all physicians should be aware of this interaction.

Effect of PK-guided tamoxifen dose escalation on endoxifen serum concentrations in CYP2D6 intermediate and poor metabolizers

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Background: Breast cancer patients with absent or reduced CYP2D6 activity may benefit less from tamoxifen treatment because of impaired biotransformation to the active metabolite endoxifen. We investigated whether a temporary one-step dose escalation of tamoxifen in CYP2D6 poor (PM) and intermediate metabolizers (IM) could increase endoxifen serum concentration to a similar level observed in CYP2D6 extensive metabolizers (EM) without increasing toxicity. Methods: From a prospective study population of early breast cancer patients using tamoxifen, 12 CYP2D6 poor and 12 intermediate metabolizers were selected and included in a one-step tamoxifen dose escalation study during two months. The escalation dose (120 mg maximum) was calculated by multiplying the individual’s endoxifen level divided by the median endoxifen concentration (33.7 nM) observed in CYP2D6 extensive metabolizers by 20 mg. Toxicity was assessed and all patients returned to the standard dose of 20 mg after two months. Results: Tamoxifen dose escalation in CYP2D6 poor and intermediate metabolizers significantly increased endoxifen concentrations (PMs: from 8.0 nM to 27.3 nM, p<0.001; IMs: from 17.8 nM to 30.3 nM, p=0.002) without increasing side effects. In intermediate but not in poor metabolizers dose escalation increased endoxifen to levels comparable with those observed in extensive metabolizers using tamoxifen 20 mg once daily (33.7 nM). Conclusions: CYP2D6 genotype and endoxifen guided tamoxifen dose escalation increased endoxifen concentrations without increasing short term side effects. Whether such tamoxifen dose escalation is effective and safe in view of long term toxic effects is uncertain and needs to be explored. Clinical trial information: NTR1509.

The impact of patient-related factors on the occurrence of febrile neutropenia in breast cancer patients receiving (neo-)adjuvant chemotherapy with 5-fluorouracil, epirubicin, and cyclofosfamide (FEC) x6 or FEC x3 followed by docetaxel (D) x3

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Background: Recently we described the impact of genetic variability on severe toxicity in breast cancer patients receiving (neo-) adjuvant FEC chemotherapy (Annals of Oncology 2013, In Press). We now further assessed the impact of a wide range of patient-related factors on FEC toxicity in routine clinical setting. Methods: Patients with early breast cancer receiving (neo-)adjuvant 6 cycles FEC or sequential 3 cycles of FEC and 3 cycles D were retrospectively evaluated through electronic chart review for febrile neutropenia (primary endpoint; CTC 3.0). Age at diagnosis, body mass index, body surface area, number of cycles received, germline genetic polymorphisms, and baseline biochemical variables (white blood cell count, absolute neutrophil count, platelets, aspartate aminotransferase, alanine aminotransferase, total bilirubin and creatinine) were available for most patients (missing data <10%). All patients had follow up for progression free survival (PFS) and overall survival (OS). Multivariate logistic regression analysis was performed including univariate associates of outcome with a p-value <0.25. Results: We identified 1,031 patients treated between 2000-2010 with 6x FEC (n=488) or 3x FEC followed by 3x D (n=543). 174 (16.9%) patients developed febrile neutropenia during FEC. After logistic regression analysis febrile neutropenia was found to be significantly associated with carriers of the rs45511401 variant T-allele in the MRP1 gene found in 12% of patients (p= 0.03, OR1.99, CI 1.07-3.71) and with increasing serum creatinine values (p=0.05 OR 4.58/CI 0.99-20.98); all other investigated patient-related parameters were not retained by the model. At a mean follow up of 5.2 years, the occurrence of febrile neutropenia was not correlated with PFS and OS. Conclusions: In this study, only the baseline level of serum creatinine and germline genetic polymorphisms in the MRP-1 gene were predictive for the occurrence of febrile neutropenia in patients receiving FEC chemotherapy. The occurrence of febrile neutropenia did not seem to impact on outcome.

Genome-wide association studies identify four ER negative-specific breast cancer risk loci

Estrogen receptor (ER)-negative tumors represent 20-30% of all breast cancers, with a higher proportion occurring in younger women and women of African ancestry. The etiology and clinical behavior of ER-negative tumors are different from those of tumors expressing ER (ER positive), including differences in genetic predisposition. To identify susceptibility loci specific to ER-negative disease, we combined in a meta-analysis 3 genome-wide association studies of 4,193 ER-negative breast cancer cases and 35,194 controls with a series of 40 follow-up studies (6,514 cases and 41,455 controls), genotyped using a custom Illumina array, iCOGS, developed by the Collaborative Oncological Gene-environment Study (COGS). SNPs at four loci, 1q32.1 (MDM4, P = 2.1 × 10(-12) and LGR6, P = 1.4 × 10(-8)), 2p24.1 (P = 4.6 × 10(-8)) and 16q12.2 (FTO, P = 4.0 × 10(-8)), were associated with ER-negative but not ER-positive breast cancer (P > 0.05). These findings provide further evidence for distinct etiological pathways associated with invasive ER-positive and ER-negative breast cancers.

Prospective study to assess fluid accumulation and tenosynovial changes in the aromatase inhibitor-induced musculoskeletal syndrome: 2-year follow-up data

BACKGROUND

Aromatase inhibitors (AIs) frequently lead to the AI-induced musculoskeletal syndrome (AIMSS). Looking into its pathophysiology, 6 months of AI therapy thickens the tendon sheath with intra-articular fluid (IAF) retention and loss of grip strength. We here report 24-month follow-up data.

PATIENTS AND METHODS

A prospective cohort study of 33 postmenopausal breast cancer patients received adjuvant endocrine therapy; 27 received an AI and 6 received tamoxifen. At baseline, 6 and 24 months patients had a rheumatologic examination, including a grip strength test, and magnetic resonance imaging of both hands and wrists. The primary end point was tenosynovial changes; secondary end points were changes in morning stiffness, grip strength and IAF.

RESULTS

Twenty-three AI and 5 tamoxifen patients completed all investigations. Between month 6 and 24, IAF further increased in AI users (P = 0.04) but not in tamoxifen users, and grip strength further decreased in both groups. The worsened tenosynovial changes were strongly correlated with a decrease in grip strength. At 24 months, morning stiffness continued to be present in over a third of AI users.

CONCLUSION

AIMSS represents a substantial problem in breast cancer patients. It is associated with tenosynovial changes, IAF retention, joint stiffness and loss of grip strength that do not improve with prolonged use.

Vitamin D status at breast cancer diagnosis: correlation with tumor characteristics, disease outcome, and genetic determinants of vitamin D insufficiency

We correlated serum 25-hydroxyvitamin D(3) (25OHD) levels with tumor characteristics and clinical disease outcome in breast cancer patients and assessed the impact of genetic determinants of vitamin D insufficiency. We collected serum from 1800 early breast cancer patients at diagnosis, measured 25OHD by radioimmunoassay (RIA), and determined genetic variants in vitamin D-related genes by Sequenom. Multivariable regression models were used to correlate 25OHD levels with tumor characteristics. Cox proportional hazard models were used to assess overall survival (OS), disease-specific survival (DSS), and disease-free interval (DFI). Lower 25OHD serum levels significantly correlated with larger tumor size at diagnosis (P = 0.0063) but not with lymph node invasion, receptor status, or tumor grade. Genetic variants in 25-hydroxylase (CYP2R1) and vitamin D-binding (DBP) protein significantly determined serum 25OHD levels but did not affect the observed association between serum 25OHD and tumor size. High serum 25OHD (>30 ng/mL) at diagnosis significantly correlated with improved OS (P = 0.0101) and DSS (P = 0.0192) and additionally had a modest effect on DFI, which only became apparent after at least 3 years of follow-up. When considering menopausal status, serum 25OHD had a strong impact on breast cancer-specific outcome in postmenopausal patients [hazards ratios for 25OHD >30 ng/mL versus ≤30 ng/mL were 0.15 (P = 0.0097) and 0.43 (P = 0.0172) for DSS and DFI, respectively], whereas no association could be demonstrated in premenopausal patients. In conclusion, high vitamin D levels at early breast cancer diagnosis correlate with lower tumor size and better OS, and improve breast cancer-specific outcome, especially in postmenopausal patients.

The impact of genetic variability on severe toxicity of (neo-) adjuvant chemotherapy in breast cancer patients receiving 5-fluorouracil, epirubicin, and cyclofosfamide (FEC)

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Background: We assessed the impact of single nucleotide polymorphisms (SNP) of potential genes of interest in germline DNA on severe adverse events in breast cancer (bc) patients receiving (neo-) adjuvant FEC chemotherapy. Methods: Cases were retrospectively evaluated through electronic chart review for febrile neutropenia (primary endpoint), febrile neutropenia first cycle, prolonged grade 4 or deep (<100/µl) neutropenia, anemia grade 3-4, thrombocytopenia grade 3-4 and non-hematological grade 3-4 events. The panel of genes, genotyped using iPLEX technology on a MALDI-TOF based MassARRAY Compact Analyser (Sequenom Inc., CA, USA), included ABCBI, ABCC1, ABCC2, ABCG2, ALDH3A1, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP3A4, CYP3A5, DPYD, FGFR4, GPX4, GSTA1, GSTP1, MTHFR, NQ01, TYMS, XPD/ERCC2, XRCC1, UGT1A1, UGT1A6 and UGT2B7. These genes are involved in the metabolization of the studied chemotherapeutics. Because of multiple testing the false discovery rate (FDR) was calculated. Results: We identified 1089 patients treated between 2000-2010 with 3-6 cycles of FEC, for whom germline DNA was available.Homozygous (TT, 0.5%) and heterozygous (GT,11%) genotypes for rs4148350 in the Multi Drug Resistance Protein I (ABCC1/MRP1), compared to wild-type (GG, 88.5%), were associated with febrile neutropenia, febrile neutropenia in first cycle, prolonged grade 4 or deep neutropenia and thrombocytopenia (80 vs 25 vs 15.7%, 40 vs 17.6 vs 9.5%, 100 vs 41.7 vs 33.8% and 20 vs 2.8 vs 0.34% respectively; p 0.0006, 0.01, 0.002 and 0.008 FDR 0.03, 0.65, 0.06 and 0.2). Variant genotypes for rs45511401 (GT/TT, 12%) in ABCC1, compared to wild-type (GG, 88%), were associated with febrile neutropenia, febrile neutropenia in first cycle and thrombocytopenia (26.5 vs 15,8%, 17.1 vs 9.7% and 3.4 vs 0.3%, respectively; p 0.007, 0.03 and 0.005, FDR 0.2, 0.75 and 0.2). Conclusions: Genetic variation in the ABCC1 gene was strongly associated with severe hematological toxicity of FEC. Other previously described SNP were not validated. This is the largest bc study in which the impact of genetic variability on the adverse events of FEC chemotherapy was investigated.

Aromatase inhibitor-induced loss of grip strength is body mass index dependent: hypothesis-generating findings for its pathogenesis

BACKGROUND

Our preliminary results showed that tenosynovial changes and decrease in grip strength are associated with the aromatase inhibitor-induced musculoskeletal syndrome (AIMSS). Here, we report the final results and assess the relationship between grip strength and body mass index (BMI).

PATIENTS AND METHODS

We conducted a prospective study including postmenopausal early breast cancer patients receiving either an aromatase inhibitor (AI) or tamoxifen. Primary end point was change from baseline in tenosynovial abnormalities. Secondary end points were changes from baseline in morning stiffness, intra-articular fluid and grip strength and its association with BMI.

RESULTS

After 6 months of therapy, 74% [95% confidence interval (CI) 51% to 89%] of AI-treated patients had worsened tenosynovial abnormalities, 56% (95% CI 34% to 75%) had increased intra-articular fluid, and 22% (95% CI 9% to 45%) had increased morning stiffness. Grip strength decreased 8% for the left hand (95% CI 2% to 21%) and 11% for the right (95% CI 4% to 17%). Regression analysis suggested that grip strength decreased more for subjects with high or with low BMI.

CONCLUSIONS

AIMSS is characterized by tenosynovial changes, intra-articular fluid and morning stiffness. We hypothesize that the quadratic association between BMI and loss of grip strength reflects AI-induced changes on the endocrine control of the growth hormone insulin-like growth factor-I pathway.

Prevalent breast cancer patients with a homozygous mutant status for CYP2D6*4: response and biomarkers in tamoxifen users

Retrospective studies suggest that single nucleotide polymorphisms in the cytochrome P450 2D6 (CYP2D6) gene predict reduced tamoxifen metabolism, better tolerance and worse treatment outcome. We hypothesized that women with this genotype lack tamoxifen-induced endometrial and biochemical changes in follicle-stimulating hormone (FSH) and sex hormone-binding globulin (SHBG). We identified 56 breast cancer patients attending the follow-up clinic with a homozygous mutant (HM) status for the CYP2D6*4 null variant. Here, we report a detailed assessment of tamoxifen activity in 19 CYP2D6 HM women, while they were using tamoxifen either for metastatic (n = 5) or for early disease (n = 14). We assessed response to tamoxifen in metastatic disease. Endometrial appearances and serum levels of FSH and SHBG were assessed from retrospective and prospective testing. Our findings do suggest that the presence of two CYP2D6*4 alleles does not exclude a durable response of tamoxifen in metastatic breast cancer. The transvaginal ultrasonographic appearance of the endometrium in CYP2D6*4/*4 patients on tamoxifen is similar as seen in the normal population of tamoxifen users. The endometrium is increased in thickness with subepithelial cysts and endometrial polyps. Serum levels of FSH and SHBG in CYP2D6*4 HM tamoxifen users were in the range of what would be expected during tamoxifen treatment in the general population. Our findings do show CYP2D6*4/*4 carriers to have activity of tamoxifen on breast cancer, endometrium and serum levels of FSH and SHBG. They support clinical trials prospectively testing the effect of CYP2D6 genetic variability in response to tamoxifen before denying this drug to breast cancer patients only based on their CYP2D6*4 status.