The impact of endoxifen-guided tamoxifen dose reductions on endocrine side-effects in patients with primary breast cancer

BACKGROUND

Tamoxifen is important in the adjuvant treatment of hormone-sensitive breast cancer and substantially reduces recurrence; however, almost 50% of patients are non-compliant mainly due to side-effects. The aim of this study was to investigate whether endoxifen-guided tamoxifen dose reduction could lead to fewer side-effects.

MATERIALS AND METHODS

Effects of tamoxifen dose reduction were investigated in patients with bothersome side-effects and endoxifen levels ≥32 nM and compared to patients with side-effects who remained on tamoxifen 20 mg. Endocrine symptoms and health-related quality of life (HR-QOL) were assessed after 3 months with the Functional Assessment of Cancer Therapy-Endocrine Symptoms (FACT-ES) questionnaire.

RESULTS

Tamoxifen dose was reduced in 20 patients, 17 of whom were assessable for side-effect analyses. A clinically relevant improvement of >6 points was observed in endocrine symptoms and HR-QOL in 41% and 65% of the patients, respectively. In total, there was a significant and clinically relevant improvement in endocrine symptoms [5.7, 95% confidence interval (CI) -0.5-11.5] and HR-QOL (8.2, 95% CI 0.9-15.4) after dose reduction. This was not seen in patients whose doses were not reduced (n = 60). In 21% of patients, endoxifen dropped slightly below the 16-nM threshold (12.8, 15.5, 15.8, 15.9 nM).

CONCLUSIONS

Endoxifen-guided dose reduction of tamoxifen significantly improved tamoxifen-related side-effects and HR-QOL. Nearly 80% of patients remained above the most conservative endoxifen threshold.

Radiological complete remission in HER2-positive metastatic breast cancer patients: what to do with trastuzumab?

PURPOSE

Patients with HER2-positive metastatic breast cancer (MBC) treated with trastuzumab may experience durable tumor response for many years. It is unknown if patients with durable radiological complete remission (rCR) can discontinue trastuzumab. We analyzed clinical characteristics associated with rCR and overall survival (OS) in a historic cohort of patients with HER2-positive MBC and studied the effect of stopping trastuzumab in case of rCR.

METHODS

We included patients with HER2-positive MBC treated with first or second-line trastuzumab-based therapy in eight Dutch hospitals between 2000 and 2014. Data were collected from medical records. We used multivariable regression models to identify independent prognostic factors for rCR and OS. Time-to-progression after achieving rCR for patients who continued and stopped trastuzumab, and breast cancer-specific survival were also evaluated.

RESULTS

We identified 717 patients with a median age of 53 years at MBC diagnosis. The median follow-up was 109 months (IQR 72-148). The strongest factor associated with OS was achievement of rCR, adjusted hazard ratio 0.27 (95% CI 0.18-0.40). RCR was observed in 72 patients (10%). The ten-year OS estimate for patients who achieved rCR was 52 versus 7% for patients who did not achieve rCR. Thirty patients with rCR discontinued trastuzumab, of whom 20 (67%) are alive in ongoing remission after 78 months of median follow-up since rCR. Of forty patients (58%) who continued trastuzumab since rCR, 13 (33%) are in ongoing remission after 68 months of median follow-up. Median time-to-progression in the latter group was 14 months.

CONCLUSIONS

Achieving rCR is the strongest predictor for improved survival in patients with HER2-positive MBC. Trastuzumab may be discontinued in selected patients with ongoing rCR. Further research is required to identify patients who have achieved rCR and in whom trastuzumab may safely be discontinued.

Abstract P6-17-19: What to do with trastuzumab therapy after achieving radiological complete remission (rCR) in HER2+ metastatic breast cancer (MBC)?

Intro MBC is generally considered incurable, but patients with HER2+ disease treated with trastuzumab do relatively well and some have an exceptional durable response and survive over 10 years. We analyzed the clinical-pathological characteristics associated with long-term survival in patients with HER2+ MBC treated with trastuzumab. In addition, we studied the effect of stopping trastuzumab in case of rCR.

Methods We included all patients with HER2+ MBC treated with first- or second-line trastuzumab-based palliative therapy between January 2000 and December 2014 in 8 Dutch hospitals (Netherlands Cancer Institute, Erasmus Medical Center, Albert Schweitzer Hospital, Reinier de Graaf Hospital, Amphia Hospital, St. Antonius Hospital, Ikazia Hospital, Haga Hospital). Patients were identified through the Netherlands Cancer Registry and linkage with the institutes' tumor registries. Data was collected from medical records using case record forms. Primary endpoint was overall survival (OS), defined as first-date of MBC until death due to any cause. Kaplan-Meier survival estimates were calculated and multivariable Cox-regression models used to identify prognostic factors for improved survival. Time to progression (TTP) after achieving rCR for patients who continued and stopped trastuzumab and breast cancer specific survival were secondary outcomes.

Results We included 744 patients (median age 53, range 24-87). Median follow-up (FU) was 109 months (range 0-178). Clinical factors associated with improved survival in multivariable analyses were single-organ metastases, ER-positivity, no skin or liver metastases, no prior trastuzumab, local therapy of metastatic disease and achievement of rCR. In line with our first single center analyses1, achievement of rCR was the strongest predictor of improved survival (multivariable HR 0.30, 95%CI 0.20-0.46). RCR was observed in 71 patients (10%), of whom 60 had been treated with trastuzumab and chemotherapy, 9 with trastuzumab and hormonal therapy, and 2 with hormonal therapy. In patients with rCR the estimated 10-year OS was 53% versus 7% in patients who did not achieve rCR (p<0.001).

Thirty patients stopped trastuzumab after achieving rCR. Median time between onset of rCR and last gift of trastuzumab in these patients was 6 months (0-132). Twenty-one patients (70%) remain in complete remission after a median FU of 75 months (range 54-90) since onset of rCR. Nine patients experienced disease progression after a median time of 14 months (range 9-62) since last gift of trastuzumab. Of these, 8 patients died due to MBC and one again achieved an ongoing rCR. Out of 39 patients who continued trastuzumab after achieving rCR, 12 are in ongoing remission after a median FU of 71 months (range 51-91). In this group median TTP was 14 months (range 5-23).

Conclusion Achieving rCR is strongly associated with long-term survival in patients with HER2+ MBC. Seventy percent of patients who stopped trastuzumab after achieving rCR remained in remission, suggesting this can be an attractive approach in selected patients. External validation of these findings is required, however, as well as additional analyses to characterize the patients -and their tumors- who achieved rCR.

1 Steenbruggen, CancerRes 2017

Citation Format: Steenbruggen TG, Bouwer NI, Smorenburg CH, Rier HN, Jager A, Beelen KJ, ten Tije AJ, de Jong PC, Drooger JC, Holterhues C, Horlings HM, Sanders J, Levin M-D, Sonke GS. What to do with trastuzumab therapy after achieving radiological complete remission (rCR) in HER2+ metastatic breast cancer (MBC)? [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 P6-17-19.

ANCA-Positive Patients: The Influence of PR3 and MPO Antibodies on Survival Rate and The Association with Clinical and Laboratory Characteristics

Objectives:

To compare the survival rate, and the clinical and laboratory characteristics in patients, characterized by the presence of certain anti-neutrophil cytoplasmic auto-antibodies (ANCAs).

Methods:

In a retrospective observational study, we analyzed the data of all patients with a positive ANCA test between 1995 and 2005 at our hospital. Based on serology patients were divided in three subgroups (ANCA-Proteinase 3 (PR3), ANCA-Myeloperoxidase (MPO) and atypical ANCA), irrespective of the diagnosis. Patient survival was compared by Kaplan Meier survival analysis. Differences in clinical and laboratory characteristics between the groups of specific ANCAs were determined.

Results:

Fifty-four ANCA-positive patients were analyzed. Eighteen of these patients were ANCA-PR3-positive, 17 were ANCA-MPO-positive and 19 had a atypical ANCA. A random control group was created of matched ANCA negative patients. Average follow-up time was 52 months. The calculated five year survival rate in respectively the ANCA-PR3- positive group, the ANCA-MPO-positive group, the atypical ANCA group and the ANCA-negative group was 45%, 81%, 90% and 100%. (P = 0.012, Wilcoxon test). A higher mean leukocyte count, a higher mean erythrocyte sedimentation rate and more fever was observed in the ANCA-PR3-positive group compared to the ANCA-MPO-positive group.

Conclusions:

A remarkable lower survival rate was observed in ANCA-PR3-positive patients compared to ANCA-MPO-positive patients. We also demonstrated that patients characterized by the presence of a defined ANCA differ in clinical and laboratory characteristics.

Ethnic differences in prenatal growth and the association with maternal and fetal characteristics

OBJECTIVES

The objectives of this study were to determine ethnic differences in prenatal growth and to examine their association with differences in maternal and fetal characteristics such as maternal height, weight, age, parity and fetal gender.

METHODS

A total of 1494 women from Rotterdam, The Netherlands, with a low-risk pregnancy who participated in a population-based cohort study, the Generation R Study, were offered three ultrasound examinations during pregnancy. Multilevel modeling was applied to determine ethnic differences in (estimated) fetal weight (including birth weight) and in the separate biometric variables that were used to calculate the estimated fetal weight (abdominal circumference, head circumference and femur length). Additionally the association of ethnic differences with maternal and fetal characteristics (i.e. maternal weight, height, age, parity and fetal gender) was studied.

RESULTS

Turkish, Cape Verdian, Surinamese-Creole and Surinamese-Hindustani women had on average smaller fetuses than the native Dutch women. The differences became more pronounced towards term. In the Turkish group the differences were no longer statistically significant when adjusted for maternal weight, height, age, parity and fetal gender. In the Cape Verdian, Surinamese-Creole and Surinamese-Hindustani groups the differences decreased after adjustment (31%, 16% and 39%, respectively).

CONCLUSIONS

This study shows that there are ethnic differences in fetal growth, which to a large extent may be attributed to differences in maternal weight, height, age and parity. For some ethnic groups, however, additional factors are involved, as differences remain significant after correction for fetal and maternal characteristics.