Optimizing Postneoadjuvant Treatment in Patients With Early Breast Cancer Achieving Pathologic Complete Response

pCR should be integrated with other prognostic factors to optimize postneoadjuvant treatments in BC.

Sequencing of Endocrine and Targeted Therapies in Hormone-Sensitive, Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.Optimizing the selection and sequencing of endocrine and targeted therapies for hormone-sensitive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer is a rapidly evolving field owing in large part to an increasing pace of drug development coupled with a greater understanding of the genomic drivers of breast cancer. The recently published results from the MAINTAIN clinical trial begin to answer an important question in this patient population-can the well-established benefit with first-line cyclin-dependent kinase 4/6 (CDK 4/6) inhibitors be stretched further by continuing this drug class beyond progression and selecting an alternate endocrine therapy partner? We present a case of a patient with hormone-sensitive HER2 low metastatic breast cancer who underwent circulating tumor DNA next-generation sequencing to better inform her treatment options after progression on first-line therapy with a CDK 4/6 inhibitor and aromatase inhibitor. Our clinical approach in this patient population prioritizes the identification of actionable mutations with high-quality evidence for efficacy on the basis of clinical trials post-CDK 4/6 inhibitors, while balancing comorbidities and patient priorities for care. Several recent clinical trials discussed herein present clinically meaningful results linking emerging targeted therapies to actionable alterations in PIK3CA, ESR1, AKT1, and PTEN. Continued drug development in this space delays time to treatment with chemotherapy, and hopefully contributes to maintaining a high quality of life for these patients on primarily oral-based therapy.

Overall survival with neratinib after trastuzumab-based adjuvant therapy in HER2-positive breast cancer (ExteNET): A randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

ExteNET showed that neratinib, an irreversible pan-HER tyrosine kinase inhibitor, given for 1 year after trastuzumab-based therapy significantly improved invasive disease-free survival in women with early-stage HER2-positive breast cancer. We report the final analysis of overall survival in ExteNET.

METHODS

In this international, randomised, double-blind, placebo-controlled, phase 3 trial, women aged 18 years or older with stage 1-3c (amended to stage 2-3c) HER2-positive breast cancer who had completed neoadjuvant and adjuvant chemotherapy plus trastuzumab were eligible. Patients were randomly assigned to oral neratinib 240 mg/day or placebo for 1 year. Randomisation was stratified according to hormone receptor (HR) status (HR-positive vs. HR-negative), nodal status (0, 1-3 or 4+), and trastuzumab regimen (sequentially vs. concurrently with chemotherapy). Overall survival was analysed by intention to treat. ExteNET is registered (Clinicaltrials.gov: NCT00878709) and is complete.

RESULTS

Between July 9, 2009, and October 24, 2011, 2840 women received neratinib (n = 1420) or placebo (n = 1420). After a median follow-up of 8.1 (IQR, 7.0-8.8) years, 127 patients (8.9%) in the neratinib group and 137 patients (9.6%) in the placebo group in the intention-to-treat population had died. Eight-year overall survival rates were 90.1% (95% CI 88.3-91.6) with neratinib and 90.2% (95% CI 88.4-91.7) with placebo (stratified hazard ratio 0.95; 95% CI 0.75-1.21; p = 0.6914).

CONCLUSIONS

Overall survival in the extended adjuvant setting was comparable for neratinib and placebo after a median follow-up of 8.1 years in women with early-stage HER2-positive breast cancer.

21-Gene Assay to Inform Chemotherapy Benefit in Node-Positive Breast Cancer

BACKGROUND

The recurrence score based on the 21-gene breast-cancer assay has been clinically useful in predicting a chemotherapy benefit in hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative, axillary lymph-node-negative breast cancer. In women with positive lymph-node disease, the role of the recurrence score with respect to predicting a benefit of adjuvant chemotherapy is unclear.

METHODS

In a prospective trial, we randomly assigned women with hormone-receptor-positive, HER2-negative breast cancer, one to three positive axillary lymph nodes, and a recurrence score of 25 or lower (scores range from 0 to 100, with higher scores indicating a worse prognosis) to endocrine therapy only or to chemotherapy plus endocrine (chemoendocrine) therapy. The primary objective was to determine the effect of chemotherapy on invasive disease-free survival and whether the effect was influenced by the recurrence score. Secondary end points included distant relapse-free survival.

RESULTS

A total of 5083 women (33.2% premenopausal and 66.8% postmenopausal) underwent randomization, and 5018 participated in the trial. At the prespecified third interim analysis, the chemotherapy benefit with respect to increasing invasive disease-free survival differed according to menopausal status (P = 0.008 for the comparison of chemotherapy benefit in premenopausal and postmenopausal participants), and separate prespecified analyses were conducted. Among postmenopausal women, invasive disease-free survival at 5 years was 91.9% in the endocrine-only group and 91.3% in the chemoendocrine group, with no chemotherapy benefit (hazard ratio for invasive disease recurrence, new primary cancer [breast cancer or another type], or death, 1.02; 95% confidence interval [CI], 0.82 to 1.26; P = 0.89). Among premenopausal women, invasive disease-free survival at 5 years was 89.0% with endocrine-only therapy and 93.9% with chemoendocrine therapy (hazard ratio, 0.60; 95% CI, 0.43 to 0.83; P = 0.002), with a similar increase in distant relapse-free survival (hazard ratio, 0.58; 95% CI, 0.39 to 0.87; P = 0.009). The relative chemotherapy benefit did not increase as the recurrence score increased.

CONCLUSIONS

Among premenopausal women with one to three positive lymph nodes and a recurrence score of 25 or lower, those who received chemoendocrine therapy had longer invasive disease-free survival and distant relapse-free survival than those who received endocrine-only therapy, whereas postmenopausal women with similar characteristics did not benefit from adjuvant chemotherapy. (Funded by the National Cancer Institute and others; RxPONDER ClinicalTrials.gov number, NCT01272037.).

Breast Cancer Index (BCI) and prediction of benefit from extended aromatase inhibitor (AI) therapy (tx) in HR+ breast cancer: NRG oncology/NSABP B-42

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Background: The BCI HOXB13/IL17BR ratio (BCI-H/I) has been shown to predict endocrine tx (ET) and extended ET (EET) benefit. We examined the effect of BCI-H/I for EET benefit prediction in NSABP B-42, evaluating extended letrozole tx (ELT) in HR+ breast cancer patients (pts) who completed 5 yrs of ET. Methods: All pts with available primary tumor tissue were eligible. Primary endpoint was recurrence-free interval (RFI). Secondary endpoints were distant recurrence (DR), breast cancer-free interval (BCFI), and disease-free survival (DFS). Stratified Cox proportional hazards model was used. Due to a non-proportional effect of ELT on DR, time-dependent secondary analyses (≤4y, >4y) were performed. Likelihood ratio test evaluated treatment by BCI-H/I interaction. Results: In 2,179 pts analyzed (60% N0; 62% AI only; 80% HER2-), 45% were BCI-H/I-High and 55% BCI-H/I-Low. ELT showed an absolute 10y benefit of 1.6% for RFI (HR=0.77, 95% CI 0.57-1.05, p=0.10) (BCI-H/I-Low: 1.1% [HR=0.69, 0.43-1.11, p=0.13]; BCI-H/I-High: 2.4% [HR=0.83, 0.55-1.26, p=0.38]; interaction p=0.55). There was no statistically significant ELT by BCI-H/I interaction for BCFI (BCI-H/I-Low: HR=0.53, 0.36-0.78, p=0.001; BCI-H/I-High: HR=0.85, 0.60-1.21, p=0.36; interaction p=0.07) or for DFS (BCI-H/I-Low: HR=0.75, 0.58-0.95, p=0.017; BCI-H/I-High: HR=0.81, 0.64-1.04, p=0.09; interaction p=0.62). Before 4y, there was no statistically significant ELT benefit on DR in either BCI-H/I group. After 4y, BCI-H/I-High pts had statistically significant ELT benefit on DR (HR: 0.29, 0.12-0.69, p=0.003), while BCI-H/I-Low pts were less likely to benefit (HR: 0.68, 0.33-1.39, p=0.28) (interaction p=0.14). Conclusions: BCI-H/I prediction of ELT benefit on RFI was not confirmed. In time-dependent DR analyses, BCI-H/I-High pts had statistically significant benefit from ELT after 4y, while BCI-H/I-Low pts did not. Observed ELT benefit on BCFI in BCI-H/I-Low pts was primarily driven by second primary breast cancers. Additional follow-up is needed to further characterize BCI-H/I predictive ability in this study. Support: U10CA180868, -180822, U24CA196067; Novartis; Biotheranostics. Clinical trial information: NCT00382070. [Table: see text]

Updated overall survival (OS) results from the phase III MONALEESA-3 trial of postmenopausal patients (pts) with HR+/HER2- advanced breast cancer (ABC) treated with fulvestrant (FUL) ± ribociclib (RIB)

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Background: The Phase III MONALEESA-3 trial (NCT02422615) previously demonstrated a statistically significant improvement in OS with RIB, a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i), plus FUL compared with placebo (PBO) plus FUL as first-line (1L) or second-line (2L) treatment in postmenopausal pts with HR+/HER2− ABC (median, not reached vs 40.0 mo; hazard ratio [HR], 0.72; 95% CI, 0.57-0.92, P =.00455). This analysis was final per the protocol; following the unblinding of the study, pts still on study treatment in the PBO arm were allowed to cross over to the RIB arm. We report an exploratory analysis of OS after an additional median 16.9 mo of follow-up, allowing for further characterization of long-term survival benefits of RIB. Methods: Postmenopausal pts with HR+/HER2− ABC were randomized 2:1 to receive RIB + FUL or PBO + FUL in 1L and 2L settings. Updated OS was evaluated by Cox proportional hazards model and summarized using Kaplan-Meier methods. Additional postprogression endpoints such as progression-free survival 2 (PFS2), time to chemotherapy (CT), and CT-free survival were also evaluated and summarized. Results: At the data cutoff (Oct 30, 2020), the median follow-up was 56.3 mo (min, 52.7 mo) and 68 (14.0%) and 21 (8.7%) patients were still on treatment in the RIB vs PBO arms, respectively. With this extended follow-up, RIB + FUL continued to demonstrate an OS benefit vs PBO + FUL (median, 53.7 vs 41.5 mo; HR, 0.73; 95% CI, 0.59-0.90). RIB + FUL had prolonged OS vs PBO + FUL in the 1L (median, not reached vs 51.8 mo; HR, 0.64; 95% CI, 0.46-0.88) and 2L subgroups (median, 39.7 vs 33.7 mo; HR, 0.78; 95% CI, 0.59-1.04). Subgroup analyses also showed a consistent OS benefit compared with the intent-to-treat (ITT) population for most subgroups. PFS2, time to CT, and CT-free survival for the ITT population favored RIB + FUL (Table). Among pts who discontinued study treatment, 81.9% and 86.4% received a next-line subsequent antineoplastic therapy, while 14.0% and 30.0% received a CDK4/6i as any subsequent line in the RIB vs PBO arms, respectively. No new safety signals were observed. Conclusions: The previously demonstrated robust and clinically meaningful OS benefit with RIB + FUL compared with PBO + FUL was maintained after almost 5 years of follow-up in postmenopausal pts with HR+/HER2− ABC. The OS benefit of RIB was observed in the 1L and 2L subgroups, which further supports the use of RIB in these populations. The results also demonstrated a significant delay in the use of subsequent CT with RIB vs PBO. Clinical trial information: NCT02422615 .[Table: see text]

Utility of the 70-gene MammaPrint assay for prediction of benefit from extended letrozole therapy (ELT) in the NRG Oncology/NSABP B-42 trial

502

Background: The 70-gene MammaPrint (MP) assay predicts risk of distant recurrence (DR) in hormone-receptor positive early-stage breast cancer and classifies cancers as Low Risk or High Risk. NSABP B-42 evaluated ELT in patients (pts) who had completed 5 yrs of adjuvant endocrine therapy (tx). The primary objective was to determine the utility of MP to identify pts enrolled in NSABP B-42 who are likely to benefit from ELT. Methods: A total of 1,866 pts from B-42 had available MP results. Primary endpoint is DR. Secondary endpoints are disease-free survival (DFS) and breast cancer-free interval (BCFI). For the primary analysis, pts were classified as High Risk (MP-H) (MP score ≤0.000) or Low Risk (MP-L) (MP score > 0.000). Exploratory analyses were performed for MP-L subcategories: MP Ultralow Risk (MP-UL) (MP score > 0.355) and MP-L but not MP-UL (MP-LNUL) (MP score > 0.000, ≤0.355). Likelihood ratio test based on stratified Cox proportional hazards (PH) model was used for treatment by risk group interaction. Stratified log-rank test was used to compare treatment groups. Hazard ratios and 95% CI were computed based on the stratified Cox PH model. Results: Among 1,866 pts, 706 (38%) were MP-H and 1,160 (62%) were MP-L. Of the MP-L, 252 (22%) were MP-UL. There were no significant differences in the distribution of patient and tumor characteristics between the MP group and the rest of the B-42 cohort, except for HER2 status. ELT effect was more pronounced in the MP cohort than in the overall B-42 population. For DR, there was statistically significant ELT benefit in MP-L (HR = 0.43, 95% CI 0.25-0.74, p = 0.002), but not MP-H (HR = 0.65, 0.34-1.24, p = 0.19) (interaction p = 0.38). For DFS, there was statistically significant ELT benefit in MP-L, but not MP-H (interaction p = 0.015). Similar findings were observed for BCFI (interaction p = 0.006). Within subcategories of MP-L, there was statistically significant ELT benefit in MP-LNUL, but not in MP-UL for all three endpoints, however the power in MP-UL was limited due to low number of pts (Table). Clinical trial information: 00382070. Conclusions: Statistically significant ELT benefit was observed for MP-L, but not MP-H. The treatment by risk group interaction was not statistically significant for DR, but it was for DFS and BCFI. The benefit appears to be stronger in MP-LNUL than in MP-UL. NCT: 00382070. Support: U10CA180868, -180822, U24CA196067; Novartis; Agendia.[Table: see text]

Impact of duration of prior cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy on alpelisib (ALP) benefit in patients (pts) with hormone receptor–positive (HR+), human epidermal growth factor receptor-2–negative (HER2–), PIK3CA-mutated advanced breast cancer (ABC) from BYLieve

1060

Background: Mutations in PIK3CA (encoding PI3Kα) are present in ̃40% of HR+, HER2– ABC tumors and are associated with relative endocrine resistance and poor prognosis. ALP inhibits and degrades PI3Kα. Primary analyses of Cohorts A and B from the phase 2 BYLieve study demonstrated that ALP + endocrine therapy (ET; fulvestrant [FUL] or letrozole [LET]) is effective and safe in pts with HR+, HER2– PIK3CA-mutated ABC with prior CDK4/6i therapy. Here, we evaluate if duration of prior CDK4/6i-based therapy impacts benefit of ALP + ET in these 2 cohorts. Methods: Cohorts A and B of BYLieve included pre/postmenopausal women who received CDK4/6i + AI or FUL, respectively, as immediate prior therapy. Cohort A received ALP 300 mg PO QD + FUL 500 mg IM Q28D + C1D15; Cohort B received ALP 300 mg PO QD + LET 2.5 mg PO QD. Within each cohort, pts were divided into 2 subgroups per duration of prior CDK4/6i therapy (“high”/”low,” above/below median duration of therapy) and the association of progression-free survival (PFS) with this covariate was analyzed using stratified log-rank test and Cox PH model. This analysis included pts for whom duration of prior CDK4/6i therapy was known, and efficacy was assessed in pts with centrally confirmed PIK3CA mutation in tumor tissue. Results: Of the 126 pts in Cohort A with duration of prior CDK4/6i available, 120 had centrally confirmed PIK3CA-mutated disease; 60 were exposed to CDK4/6i for > 380 days (high) and 60 for < 380 days (low), with similar demographics/disease characteristics between subgroups. There was no significant difference in PFS between the high vs low subgroups (HR 1.03; 95% CI, 0.64-1.64; P= 0.927; median 8.0 vs 7.0 mo). Grade ≥3 adverse events (AEs) were experienced by 66.9% (n = 85) of all pts in Cohort A and 66.7% (n = 42)/68.3% (n = 43) in the high/low subgroups, respectively. Of the 123 pts in Cohort B with duration of prior CDK4/6i available, 113 had centrally confirmed PIK3CA-mutated disease; 57 were exposed to CDK4/6i for > 305 days (high) and 56 for < 305 days (low), with similar demographics/disease characteristics between subgroups. There was no significant difference in PFS between high vs low subgroups (HR 1.20; 95% CI, 0.78-1.84; P= 0.400; median 5.4 vs 5.9 mo). Grade ≥3 AEs were experienced by 69.8% (n = 88) of all pts in Cohort B and 71.0% (n = 44)/68.9% (n = 42) in the high/low subgroups, respectively. Conclusions: This analysis demonstrates that the benefit and safety profiles of ALP + ET are similar in pts with HR+, HER2– PIK3CA-mutated ABC who achieved relatively shorter duration of disease control with prior CDK4/6i vs those with longer duration of disease control, and suggests that ALP overcomes acquired resistance to CDK4/6i in these pts. Clinical trial information: NCT03056755 .

Impact of oligometastatic disease on survival in ER positive breast cancer: A population-based analysis

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Background: Estrogen positive (ER) advanced breast cancers (ABC) are associated with a longer survival compared to other subtypes. However, clinical equipoise remains for the management of oligometastatic disease. While recent phase I and II data support the use of metastasis-directed therapy, breast cancer patients remain underrepresented and real-world outcomes for breast cancer patients with directed treatment for oligometastases is lacking. Methods: The BC Cancer Breast Cancer Outcomes Unit (BCOU) database was utilized to identify patients with ER positive breast cancer referred to BC Cancer from 2005-2014 with documented metastases. Baseline clinical, pathological and treatment data were compiled. Overall survival (OS) was compared between the group with oligometastatic disease(OM) (defined as < = 5 foci of metastases) and the group with non-oligometastatic disease (defined as > = 6 foci of metastases) using Kaplan-Meier survival curves. Key secondary endpoints included metastasis-directed treatment impact, based on the site of metastasis, local control (LC) and distant failure (DF) rate. Results: A total of 938 patients met the inclusion criteria. Of these, 191 (20.4%) had OM and 747 (79.6%) had widespread disease at 1st diagnosis of ABC. The groups were well balanced for clinical characteristics (all p > 0.05), with a median age of 59yrs (23-99). 84% were ductal carcinomas, 14% were also HER2 positive. Sites of oligometastases were bone (66.5%), liver (12.0%), brain (8.4%) and lung (5.8%). Median follow-up was 7.4 yrs. Median OS was 24 mo (95% CI 20.2, 27.8) for patients with OM and 11 mo (9.5, 12.5) for those with widespread disease (p < 0.0001). In the OM group, 114 (59.7%) of patients received metastasis-directed treatment, whereas 77 (40.3%) did not. Treatment modalities included radiation in 53.4% of patients, surgery in 8.9% of patients and stereotactic body radiotherapy (SBRT) in 3.7%. Median OS was 24 mo (18.3, 29.7) for patients who received metastasis-directed treatment and 23 mo (17.5, 28.5) for those who did not (p = 0.954). Patients with bone-only metastases had a median OS of 27mo with directed treatment and 25mo without directed-treatment (p = 0.334). Conclusions: Oligometastatic state was associated with a significantly better OS. Metastasis-directed treatment was associated with a non-significant OS difference in patients with bone-only metastases in a real world cohort. However, the impact of modern systemic treatment and SBRT methods are evolving. Large prospective randomized studies of this approach merit further study.

Overall survival (OS) in patients (pts) with advanced breast cancer (ABC) with visceral metastases (mets), including those with liver mets, treated with ribociclib (RIB) plus endocrine therapy (ET) in the MONALEESA (ML) -3 and -7 trials

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Background: In the Phase III ML-3 (NCT02422615) and ML-7 (NCT02278120) trials, RIB + ET demonstrated a significant OS benefit (ML-3: HR, 0.72, P = 0.00455; ML-7: HR, 0.71, P = 0.00973) over placebo (PBO) + ET in pts with HR+/HER2- ABC (Im et al. N Engl J Med. 2019; Slamon et al. N Engl J Med. 2019). The presence of visceral mets generally portends a poor prognosis, which is especially poor in pts with liver mets (He et al. Ann Oncol. 2019). Here we report OS in pts with visceral mets with a focus on those with liver mets in ML-3 and ML-7. Methods: In ML-3, postmenopausal pts were randomized 2:1 to receive RIB + fulvestrant (FUL) or PBO + FUL as first- (1L) or second-line (2L) treatment. In ML-7, premenopausal pts were randomized 1:1 to receive RIB + ET or PBO + ET (this analysis included only pts who received an NSAI as ET partner to match approved indication). Results: Visceral mets were identified in 293 pts (60.5%) in the RIB arm and 147 (60.7%) in the PBO arm in ML-3 and 150 (44.8%) and 142 pts (42.1%), respectively, in ML-7. In ML-3, the median age of pts with visceral mets was 63 and 65 years in the RIB and PBO arms, and in ML-7 it was 42.5 and 45.0 years, respectively. In ML-3, 214 pts with visceral mets received 1L therapy (RIB, n = 137; PBO, n = 77), while 219 pts received 2L therapy or had early relapse (RIB, n = 151; PBO, n = 68). Lung and liver were the most common sites of visceral mets for pts in ML-3 (49.8% and 44.8%, respectively) and ML-7 (51.4% and 58.2%, respectively). OS HRs in pts with visceral mets were consistent with the benefit in the overall pt populations and suggested a particularly substantial OS benefit in pts with liver mets (HR for liver mets group in ML-3, 0.629 [95% CI, 0.421-0.942]; HR in ML-7, 0.531 [95% CI, 0.321-0.877]; Table). No new safety signals were observed. Conclusions: Approximately half of the pts in ML-3 and ML-7 had visceral mets. The OS data in these pts are consistent with the benefit observed with RIB in the overall populations of each trial. In pts with liver mets, a group with an especially poor prognosis, RIB + ET demonstrated a substantial OS benefit compared with PBO + ET. Clinical trial information: NCT02422615; NCT02278120 . [Table: see text]

Impact of sequence order of anthracyclines and taxanes in neoadjuvant chemotherapy for breast cancer: Results from a prospective institutional database

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Background: There has been growing interest in the optimal sequencing of anthracyclines and taxanes in neoadjuvant chemotherapy (NACT) for breast cancer. However, data comparing efficacy of administering taxanes prior to anthracyclines as opposed to the opposite sequence remains limited and inconsistent. The objective of our study was to assess the impact of sequence order on pathologic and clinical outcomes in a real-world setting. Methods: A prospective institutional database was analyzed to identify all HER2-negative breast cancer patients treated with NACT from 2012 to 2019. Rates of pathologic complete response (pCR), down-staging, and breast-conserving surgery were compared between patients who received anthracyclines followed by taxanes (AC-T) to those who received taxanes followed by anthracyclines (T-AC). Chi-square and independent sample non-parametric tests were used to test for associations between variables and outcomes. Results: Of the 270 patients who met eligibility criteria, 175 (65%) received AC-T and 95 (35%) received T-AC. Median age was 55 (IQR 24-86). Overall, 83% of patients had stage IIB or greater tumors, 40% had grade 3 histology, and 36% had triple-negative disease. Characteristics were balanced between the AC-T and T-AC groups (all p < 0.05). Median duration of treatment with NACT was 102 days (IQR 29-203). Rates of pCR (19% vs 21%, p = 0.750), down-staging (68% vs 61%, p = 0.188), and conversion to breast-conserving surgery (26% vs 20%, p = 0.314) were similar for AC-T vs T-AC, respectively. pCR was higher in triple-negative compared to hormone-positive cases (33% vs 13%, p < 0.001). Conclusions: In this small population-based cohort, sequence order of anthracyclines and taxanes did not demonstrate statistically significant differences in evaluated outcomes from NACT for breast cancer. This supports the current variation in prescribing practice and highlights the need for further studies in this area.

Application of neo-bioscore to a real-world cohort: Potential implications for patient selection, for escalation, and de-escalation of therapy

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Background: Recent studies have demonstrated that escalation of therapy for patients with residual disease after neoadjuvant therapy for breast cancer may result in better long-term outcomes. However, refining patient selection based on prognosis has not been widely adopted. The Neo-Bioscore is a validated independent prognostic tool that can be readily applied clinically. The utility of this tool to predict the expected magnitude of benefit from escalation of therapy for ER+, HER2+ and TNBC disease has not yet been explored. Methods: A retrospective review of prospectively collected data from May 2012-May 2019 of patients treated with neoadjuvant chemotherapy followed by surgery was undertaken. The Neo-Bioscore was calculated for each patient. Kaplan-Meier method was used to generate disease-specific survival (DSS) curves, and 5-year DSS rates were estimated. These estimates were compared to those predicted by the original validation cohort. The potential benefit of further adjuvant therapy was extrapolated from data available in the published literature. Results: A total of 471 patients were included in this study; all were women, and the median age was 56 (range 24-88). 324 had residual disease at the time of surgery (68%). Median follow up from diagnosis was 4.4 years. 5-year DSS for each Neo-Bioscore category is seen in the Table below. This correlated with the predicted DSS with a correlation coefficient of X. For patients with residual disease, utilization of adjuvant capecitabine for those with ER+ or TNBC and utilization of adjuvant TDM-1 for those with Her2+ disease would have minimal impact on DSS in those with Neo-Bioscore of 0-2, modest benefit for those with Neo-Bioscore of 3-4, and would be of high benefit for those with Neo-Bioscore of 5 or higher. Conclusions: Neo-Bioscore is a tool that can be readily applied to a real-world cohort without additional pathological information, with good correlation to the predicted outcomes in validation studies. The impact and utility of the Neo-Bioscore to stratify patients for selection of adjuvant therapy will need to be validated, but may help better inform treatment in resource constrained environments. [Table: see text]

Pooled ctDNA analysis of the MONALEESA (ML) phase III advanced breast cancer (ABC) trials

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Background: Biomarker analyses have been presented separately for each Phase III ML trial, which tested efficacy and safety of ribociclib (RIB) with different endocrine therapy (ET) combination partners as first- or second-line treatment for hormone receptor–positive, HER2-negative (HR+/HER2−) ABC. Here, using the largest pooled biomarker dataset of a CDK4/6 inhibitor in ABC to date, we identify potential biomarkers of response or resistance to RIB across ML trials. Methods: Baseline ctDNA from 1503 patients (pts) enrolled in ML-2, 3, and 7 was assessed using next-generation sequencing with a targeted panel of 557 genes. Genes with an alteration frequency ≥2% and in ≥15 pts per treatment arm were included (83 genes). Genetic alteration was defined as presence of a mutation, short insertion/deletion, or copy number alteration. Cox proportional hazard model of progression-free survival (PFS) was fit with gene-by-treatment interaction. Genes with interaction P< 0.10 and genes of interest were investigated. Results: Pts with alterations in FRS2 and PRKCA (treatment interaction P< 0.05) as well as MDM2, ERBB2, AKT1, and BRCA1/2 ( P> 0.05 but considered actionable) had a trend for increased PFS benefit of RIB vs PBO (Table). Pts with alterations in CHD4, BCL11B, ATM, or CDKN2A/2B/2C derived little to no added PFS benefit with RIB vs PBO ( P interaction < 0.10; hazard ratio [HR] > 0.80). Data on genes implicated in the literature as potential mechanisms of resistance to ET and/or CDK4/6 inhibition ( ESR1, PTEN, FAT1, RB1, and NF1) will be presented. Conclusions: Results of this pooled analysis of the ML-2, 3, and 7 trials, the largest biomarker analysis of any CDK4/6 inhibitor in ABC, revealed several potential biomarkers of response ( FRS2, MDM2, PRKCA, ERBB2, AKT1, and BRCA1/2) or resistance ( CHD4, BCL11B, ATM, or CDKN2A/2B/2C) to RIB. Clinical trial information: NCT01958021; NCT02422615; NCT02278120 . [Table: see text]

Alpelisib (ALP) + fulvestrant (FUL) in patients (pts) with PIK3CA-mutated (mut) hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (ABC) previously treated with cyclin-dependent kinase 4/6 inhibitor (CDKi) + aromatase inhibitor (AI): BYLieve study results

1006

Background: PIK3CA mutations (mut) occur in ~40% of pts with HR+, HER2– ABC and are associated with poor prognosis and resistance to treatment (tx). ALP, a PI3Kα inhibitor, plus FUL demonstrated efficacy in the phase 3 SOLAR-1 trial of HR+, HER2– PIK3CA-mut ABC. Little clinical data and few prospective studies are available to inform tx decisions for pts with HR+, HER2– PIK3CA-mut ABC in the post-CDKi setting. BYLieve is the first trial evaluating ALP + endocrine therapy (ET; FUL or letrozole) in pts with HR+, HER2– PIK3CA-mut ABC who progressed on/after prior therapy, including CDKi. In this ongoing phase 2, open-label, noncomparative study, 112 pts with centrally confirmed PIK3CA mut in tumor tissue are enrolled in each cohort per immediate prior tx of CDKi + AI, CDKi + FUL, or systemic chemo or ET. Enrollment is complete in prior CDKi + AI and CDKi + FUL cohorts and ongoing in prior systemic chemo or ET cohort. We report on the cohort of pts with CDKi + AI as immediate prior tx. Methods: Pts received ALP 300 mg/day + FUL 500 mg Q28D + C1D15. Primary endpoint was proportion of pts alive without disease progression at 6 mo per local assessment; 2-sided 95% confidence intervals (CI) were calculated using Clopper and Pearson (1934) exact method. Evidence of clinically meaningful tx effect was defined as the lower bound of the 95% CI > 30%. Safety was assessed in all patients; AEs presented by preferred term. Results: 127 pts whose immediate prior tx was CDKi + AI were enrolled, of whom 121 had centrally confirmed PIK3CA mut; median follow-up was 11.7 mo. Primary endpoint was met: proportion of pts without disease progression at 6 mo was 50.4% (95% CI, 41.2-59.6). Most frequent all-grade AEs were diarrhea (60%), hyperglycemia (58%), nausea (46%), fatigue (29%), decreased appetite (28%), and rash (28%). Most frequent grade ≥3 AEs included hyperglycemia (28%), rash (9%), and rash maculopapular (9%). Incidence of AEs leading to discontinuation was low; most frequent AEs leading to discontinuation were rash (5 pts, 3.9%), colitis, hyperglycemia, urticaria, and vomiting (2 pts, 1.6% each). Conclusions: With follow-up still ongoing, BYLieve shows in a large number of pts that ALP + FUL demonstrates clinically meaningful efficacy and manageable toxicity post CDKi tx. Building on findings from SOLAR-1, BYLieve further supports use of ALP + FUL for HR+, HER2– PIK3CA-mut ABC. Clinical trial information: NCT03056755 .

Comparative efficacy of neoadjuvant to adjuvant chemotherapy for the treatment of early-stage HER2 negative breast cancer: A population-based analysis

e12100

Background: The use of neoadjuvant treatment has increased over the past decade due to its ability to assess tumour sensitivity to systemic treatment in vivo, and to downstage women for increased breast conserving surgery. Recent studies have stratified patients with residual disease to receive additional treatment, which has resulted in meaningful improvements in survival. However, meta-analysis data suggest similar long-term outcomes for patients treated with neoadjuvant chemotherapy (NACT) compared to adjuvant chemotherapy (ACT) in historical randomized trials. The comparative efficacy in a real-world setting utilizing modern chemotherapy regimens is unknown. Methods: A retrospective review of the BC Cancer Breast Cancer Outcomes Unit (BCOU) was performed to identify patients with stage I-III HER-2 negative breast cancer treated with chemotherapy at the BC Cancer Agency from 2005-2010. Patients were then divided into 2 groups: those who received neoadjuvant chemotherapy (NACT) and those who received adjuvant chemotherapy (ACT). A matched analysis (age, stage, subtype) for patients treated with NACT vs ACT (matched 1:3) was then performed using a propensity scoring method to compare distant disease-free survival (DDFS), breast cancer specific survival (BCSS) and overall survival (OS). No patients received adjuvant chemotherapy for residual disease after NACT. Results: A total of 656 patients met the inclusion criteria, consisting of 164 NACT and 492 ACT cases. Median age was 49 years (37-68) in the NACT group vs 49 (37-65) in the ACT group (p = 0.71). The majority had stage 3 disease, 64% in both groups (p = 1.0). Most were hormone receptor positive (HR+), 67.1% vs 70.7% in the NACT vs ACT groups, respectively (p = 0.41). 5-year DDFS was 75% with NACT (95%CI 67, 82) and 77% with ACT (95%CI 72, 81), p = 0.87. 5-year OS for patients treated with NACT was 77% (95%CI 71, 84) and 80% (95%CI 75, 85) for patients treated with ACT, p = 0.33. 5-year BCSS was 80% with NACT (95% CI 70, 86) and 82% (95%CI 77, 86) with ACT, p = 0.75. Multivariate analysis for tumour size, nodal involvement and subtype are ongoing. Conclusions: The use of NACT compared to ACT in a population-based setting did not result in significant differences in DDFS, OS or BCSS. Acknowledging the comparative efficacy of these approaches will be informative to determine if the addition of subsequent adjuvant treatment for patients with residual disease after NACT will lead to differential benefits in a population-based setting.

Leeomic: A comprehensive proteomic analysis towards discovery of predictive patterns of protein expression to ribociclib sensitivity and resistance—A compLEEment-1 Canadian correlative sub-study

TPS3170

Background: Despite developments in the treatment of advanced hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) breast cancer, primary or acquired resistance eventually occurs in all cases and there is still very limited understanding of the mechanisms of resistance to therapy. LEEOMIC is a sub-study of the main CompLEEment-1 ( N = 3255 patients enrolled, CLEE011A2404 v03) trial, an open-label, phase 3b study evaluating ribociclib + letrozole as first-line therapy in an expanded advanced breast cancer patient population which recruited over 250 Canadian patients. The purpose of this Canadian correlative sample collection study is to explore the mechanisms of response and resistance to ribociclib in combination with letrozole through proteomic and ctDNA analysis. Methods: The British Columbia Cancer Research Centre team developed a novel and optimized MS/MS platform called SP3-Clinical Tissue Proteomics (SP3-CTP) to perform in-depth proteome profiling ( > 8,000 proteins) from formalin fixed paraffin embedded (FFPE) material (10-micron section). SP3-CTP analysis of the proteome of the study patients who did not achieve clinical benefit (primary resistance: progression within 3 months of treatment) will be compared to the proteome of the sub-group of prolonged responders (time to progression of 22 months or more) in order to identify biomarkers that can predict response or de-novo resistance to therapy. Archival tumor biopsies (primary or metastatic) collected from the study will be submitted for proteomic analysis to identify proteomic expression levels that may serve as predictor of response. It is anticipated that over 150 samples will be collected. If available, blood samples taken at time of progression or end of treatment will also be analyzed for ctDNA for genetic profiling and to study if there is any correlation between genetic mutations and response or resistance to therapy. Currently, both tissue and blood samples are being collected and no analysis has been conducted thus far. Clinical trial information: NCT03613220.

NATALEE: Phase III study of ribociclib (RIBO) + endocrine therapy (ET) as adjuvant treatment in hormone receptor–positive (HR+), human epidermal growth factor receptor 2–negative (HER2–) early breast cancer (EBC)

TPS597

Background: RIBO is a selective inhibitor of CDK4/6 with demonstrated efficacy and is well tolerated when combined with ET in pre-/peri- and postmenopausal women with HR+, HER2– advanced breast cancer. Given these findings and considering the role of CDK4/6–Rb–E2F pathway dysregulation in ET resistance, there is a rationale for evaluating whether RIBO + ET prevents, or delays acquired resistance to ET in the adjuvant setting, to improve invasive disease-free survival (iDFS). Methods: The phase 3 multicenter, randomized, open-label NATALEE trial will evaluate the efficacy and safety of RIBO + ET as adjuvant treatment in patients with HR+, HER2– EBC. Eligible women (any menopausal status) and men aged ≥ 18 years will be randomized to RIBO 400 mg/day (3 weeks on/1 week off) + ET or ET alone. In both arms, ET will comprise daily continuous letrozole 2.5 mg/day or anastrozole 1 mg/day; men and premenopausal women will also receive goserelin 3.6 mg once every 28 days. Treatment with RIBO will last 36 months whereas treatment with ET (in both arms) will last 60 months. Patients must have had American Joint Committee on Cancer (8th ed.) Anatomic Stage II (either N0 with grade 2-3 and/or Ki67 ≥ 20% or N1) or III EBC, with an initial diagnosis ≤ 18 months prior to randomization, and completed chemotherapy and radiotherapy (if indicated). Patients receiving standard (neo)adjuvant ET are eligible only if this treatment was initiated within 12 months of randomization. Key exclusion criteria include previous CDK4/6 inhibitor treatment and clinically significant, uncontrolled heart disease and/or cardiac repolarization abnormality. The primary endpoint is iDFS using STEEP (Standardized Definitions for Efficacy End Points) criteria as assessed by the investigator; secondary endpoints include recurrence-free survival, distant DFS, overall survival, patient-reported outcomes, and RIBO pharmacokinetics. Safety and tolerability will also be evaluated. Estimated enrollment is 4000 patients from 425 sites in 21 countries. Recruitment is ongoing. Clinical trial information: NCT03701334.

Alpelisib (ALP) + endocrine therapy (ET) in patients (pts) with PIK3CA-mutated hormone receptor-positive (HR+), human epidermal growth factor-2-negative (HER2-) advanced breast cancer (ABC): First interim BYLieve study results

1040

Background: In the phase 3 SOLAR-1 study, ALP + fulvestrant (FUL) improved PFS in pts with HR+, HER2– ABC with a PIK3CA mutation overall and in the small group of pts with prior cyclin-dependent kinase 4/6 inhibitor (CDKi) use. We report interim data from the BYLieve study in pts with PIK3CA-mutated ABC and prior CDKi exposure. Methods: BYLieve is an ongoing, phase 2, open-label, non-comparative study of ALP 300 mg QD + ET in men and women with PIK3CA-mutated HR+, HER2– ABC whose disease progressed on/after CDKi + ET. Pts are permitted ≤2 prior anticancer therapies and ≤1 prior chemotherapy regimen for ABC. Pts with prior CDKi and AI ( FUL cohort) receive ALP and FUL 500 mg Q28d + C1d15 IM. Pts with prior CDKi and FUL ( LET cohort) receive ALP and letrozole (LET) 2.5 mg PO QD. In this preplanned interim analysis, conducted after ≥20 pts in FUL had ≥6 mo of follow-up, descriptive data are reported for preliminary safety and efficacy in the FUL and LET cohorts. Results: At data cutoff, 64 and 36 pts were enrolled in the FUL and LET cohorts, respectively; 39 pts ( FUL, n = 21; LET, n = 18) have safety and efficacy data with ≥6 mo follow-up and are reported here. Data on 100 pts enrolled at the time of data cutoff will be presented. In the 39 pts with ≥6 mo follow-up, median ALP duration was 5.3 and 5.5 mo in FUL and LET, respectively; median duration of FUL and LET was 5.6 mo. Median relative ALP dose intensity was 93% ( FUL) and 87% ( LET). Most common grade ≥3 adverse events were hyperglycemia (38.1% ( FUL) and 27.8% ( LET)) and rash (4.8% ( FUL) and 27.8% ( LET)). Only 2 pts (5%; 1 pt per cohort) discontinued due to an AE. In pts with centrally confirmed PIK3CA mutation (n = 20 ( FUL); n = 17 ( LET)), ORR was 20% ( FUL) and 18% ( LET), CBR was 40% ( FUL) and 35% ( LET). Efficacy and safety data for the 100 enrolled pts will be presented at the meeting. Conclusions: Pending further readout of the ongoing BYLieve trial, safety and tolerability of ALP and hormonal therapy in pts with prior CDKi are consistent with those of SOLAR-1; discontinuation due to toxicity was rare. NCT03056755. Clinical trial information: NCT02437318.

Whole transcriptome sequencing in metastatic cancer: A review of expression outliers in 113 metastatic breast cancer patients

3080

Background: The genomic profiling of breast cancers has led to a greater understanding of the mutational landscape of metastatic breast cancer (MBC) with potential therapeutic implications. Despite these advances, there is a paucity of data regarding the additive value and relevance of gene expression across histological and molecular subtypes, which represents the majority of informative and actionable findings identified in the BC Cancer personalized oncogenomics program (POG). Methods: Informative findings with potential clinical application from whole genome sequencing (WGS) and whole transcriptome sequencing (WTS) in MBC patients between 2012-2018 were reviewed. Variants observed in pathway genes of potential clinical relevance, as defined by a curated list of genes, were examined across histological subtypes. High and low expression outliers relative to TCGA breast cases, defined as expression greater than 98th percentile and FC > 2 compared to Illumina breast dataset and lower than 25th percentile and FC < -2 compared to Illumina breast dataset, respectively, were then analyzed to establish how many outliers were observed in pathways of potential clinical relevance. Results: A total of 113 cases were included. WGS revealed that TP53 was the most frequent single nucleotide variant (SNV) in triple negative breast cancer (23/30, 77%), whereas PIK3CA (37/78, 47%), PTEN (11/78, 14%) and ESR1 (19/78, 24%) were most frequent in ER positive cases and CDKN2A (2/18, 11%) in HER2 positive cases. Across all subtypes, the mTOR and cell cycle pathways were found to have the highest frequency of SNVs, with the identification of 86 and 71 variants, respectively. Expression data for 113 RNA-sequenced patients revealed a high frequency of expression outliers in the mTOR pathway (26 high expression and 424 low expression outlier genes) and cell cycle pathways (35 high expression and 331 low expression outlier genes), but also in the WNT pathway (96 high expression and 490 lower expression outlier genes) and NOTCH pathway (84 high expression and 564 low expression outlier genes). Conclusions: Frequently identified SNVs across histological subtypes were correlated with expression outliers in pathways of clinical relevance in breast cancer. Additional informative findings, in pathways of potential clinical relevance not historically targeted in breast cancer, were identified with WTS. The clinical utility of these findings warrants further study.

Cctg MA.39 tailor RT: A randomized trial of regional radiotherapy in biomarker low-risk node-positive breast cancer (NCT03488693)

TPS602

Background: Biomarker low risk, ER positive (+), HER2 negative (-) breast cancer with low burden nodal involvement may be associated with good outcomes (Woodward 2016, Mamounas 2017). There is conflicting data regarding the efficacy of regional radiotherapy after breast conserving surgery (BCS) or mastectomy in these patients (Kyndi 2008, Whelan 2015, Poortmans 2015, Liu 2015). Our hypothesis is that the risk of recurrence in patients with biomarker low risk, ER+, Her2- breast cancer and involvement of 1-3 lymph nodes where regional RT is omitted will not be inferior to the risk of recurrence in patients treated with regional RT. Methods: MA39 is a Canadian Cancer Trials Group led, NCTN sponsored, randomized phase III study comparing breast cancer recurrence free interval (BCRFI) in patients with ER+, Her2-, LN 1-3+ breast cancer that is low risk as defined by Oncotype Dx Recurrence Score < 18. Secondary objectives include a comparison of DFS, breast cancer mortality, OS, locoregional and distant recurrence free intervals, toxicity, arm volume and mobility measurements, patient reported outcomes and cost effectiveness. Key eligibility criteria include: age ≥ 40 years; BCS or mastectomy with axillary dissection and 1-3 positive axillary nodes; BCS and SLNB alone and 1-2 positive axillary nodes; mastectomy and SLNB alone and only 1 positive axillary node; planned endocrine therapy ≥ 5 years; adjuvant chemotherapy allowed. Statistical design: The primary analysis will be a test of non-inferiority (NI) in the intention to treat population. If the upper bound of a one-sided 95% interval for the hazard ratio for BCRFI is < 1.4, NI will be declared. Using a one-sided α of 0.05 and a power of 87%, it is anticipated that 278 events are required. With an expected 5 years of accrual and 4.5 years of follow-up, 2140 patients are needed for the final sample size. Conduct to Date: Study activation May 30 2018. Participation as of February 2019: Registrations 64 Randomizations 26. CIRB approval for continuation of MA.39 was received on January 11 2019. Clinical trial information: NCT03488693.

Effects of neratinib on health-related quality of life in women with HER2-positive early-stage breast cancer: longitudinal analyses from the randomized phase III ExteNET trial

BACKGROUND

We report longitudinal health-related quality-of-life (HRQoL) data from the international, randomized, double-blind, placebo-controlled phase III ExteNET study, which demonstrated an invasive disease-free survival benefit of extended adjuvant therapy with neratinib over placebo in human epidermal growth factor receptor-2-positive early-stage breast cancer.

PATIENTS AND METHODS

Women (N  = 2840) with early-stage HER2-positive breast cancer who had completed trastuzumab-based adjuvant therapy were randomly assigned to neratinib 240  mg/day or placebo for 12  months. HRQoL was an exploratory end point. Patients completed the Functional Assessment of Cancer Therapy-Breast (FACT-B) and EuroQol 5-Dimensions (EQ-5D) questionnaires at baseline and months 1, 3, 6, 9, and 12. Changes from baseline were compared using analysis of covariance with no imputation for missing values. Sensitivity analyses used alternative methods. Changes in HRQoL scores were regarded as clinically meaningful if they exceeded previously reported important differences (IDs).

RESULTS

Of the 2840 patients (intention-to-treat population), 2407 patients were evaluable for FACT-B (neratinib, N  = 1171; placebo, N  = 1236) and 2427 patients for EQ-5D (neratinib, N  = 1186; placebo, N  = 1241). Questionnaire completion rates exceeded 85%. Neratinib was associated with a decrease in global HRQoL scores at month 1 compared with placebo (adjusted mean differences: FACT-B total, -2.9 points; EQ-5D index, -0.02), after which between-group differences diminished at later time-points. Except for the FACT-B physical well-being (PWB) subscale at month 1; all between-group differences were less than reported IDs. The FACT-B breast cancer-specific subscale showed small improvements with neratinib at months 3-9, but all were less than IDs. Sensitivity analyses exploring missing data did not change the results.

CONCLUSIONS

Extended adjuvant neratinib was associated with a transient, reversible decrease in HRQoL during the first month of treatment, possibly linked to treatment-related diarrhea. With the exception of the PWB subscale at month 1, all neratinib-related HRQoL changes did not reach clinically meaningful thresholds. ClinicalTrials.gov: NCT00878709.

PIK3CA alterations and benefit with neratinib: analysis from the randomized, double-blind, placebo-controlled, phase III ExteNET trial

BACKGROUND

Neratinib is an irreversible pan-HER tyrosine kinase inhibitor that inhibits PI3K/Akt and MAPK signaling pathways after HER2 receptor activation. The ExteNET study showed that neratinib significantly improved 5-year invasive disease-free survival (iDFS) in women who completed trastuzumab-based adjuvant therapy for early breast cancer (EBC). We assessed the prognostic and predictive significance of PIK3CA alterations in patients in ExteNET.

METHODS

Participants were women aged ≥ 18 years (≥ 20 years in Japan) with stage 1-3c (modified to stage 2-3c in February 2010) operable breast cancer, who had completed (neo)adjuvant chemotherapy plus trastuzumab ≤ 2 years before randomization, with no evidence of disease recurrence or metastatic disease at study entry. Patients were randomized to oral neratinib 240 mg/day or placebo for 1 year. Formalin-fixed, paraffin-embedded primary tumor specimens underwent polymerase chain reaction (PCR) PIK3CA testing for two hotspot mutations in exon 9, one hot-spot mutation in exon 20, and fluorescence in situ hybridization (FISH) analysis for PIK3CA amplification. The primary endpoint (iDFS) was tested with log-rank test and hazard ratios (HRs) estimated using Cox proportional-hazards models.

RESULTS

Among the intent-to-treat population (n = 2840), tumor specimens were available for PCR testing (991 patients) and PIK3CA FISH (702 patients). Overall, 262 samples were PIK3CA altered: 201 were mutated (77%), 52 (20%) were amplified, and 9 (3%) were mutated and amplified. iDFS was non-significantly worse in placebo-treated patients with altered vs wild-type PIK3CA (HR 1.34; 95% CI 0.72-2.50; P = 0.357). Neratinib's effect over placebo was significant in patients with PIK3CA-altered tumors (HR 0.41; 95% CI 0.17-0.90, P = 0.028) but not PIK3CA wild-type tumors (HR 0.72; 95% CI 0.36-1.41; P = 0.34). The interaction test was non-significant (P = 0.309).

CONCLUSIONS

Although there was a greater absolute risk reduction associated with neratinib treatment of patients with PIK3CA-altered tumors in ExteNET, current data do not support PIK3CA alteration as a predictive biomarker of response to neratinib in HER2-positive EBC.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT00878709 . Trial registered April 9, 2009.

Clinical application and utility of genomic assays in early-stage breast cancer: key lessons learned to date

Early-stage hormone receptor-positive breast cancer is the most common subtype and stage presenting in countries with organized screening programs. Standard clinical and pathologic factors are routinely used to support prognosis and decisions about adjuvant therapies. Hormone receptor and her2 status are essential for decision-making about the use of adjuvant hormonal and anti-her2 therapies respectively. Genomic assays are now commercially available to aid in either further prognostication or in refining the potential benefit of adjuvant chemotherapy. The current genomic assays all generally quantify estrogen receptor and proliferation gene sets (among others) by rna expression, although the specific genes assayed are quite discordant. The present review focuses on the pivotal studies in which each assay attempted to demonstrate clinical utility, with an emphasis on prospective trial data for each assay, if available. Using genomic assays, health care providers will increasingly be able to individualize therapy or de-escalate therapy, optimizing clinic benefit while minimizing toxicities from systemic therapies.

Abstract P1-13-03: Effects of neratinib after trastuzumab-based adjuvant therapy in hormone receptor-positive HER2+ early-stage breast cancer: Exploratory analyses from the phase III ExteNET trial

Background: The international, randomized, placebo-controlled phase III ExteNET trial showed that a 1-year course of neratinib after trastuzumab-based adjuvant therapy significantly improved 2-year invasive disease-free survival (iDFS) in patients with early-stage HER2+ breast cancer (BC) (hazard ratio 0.67; 95% CI 0.50–0.91; p=0.009) [Chan et al. Lancet Oncol 2016]. The significant iDFS benefit with neratinib was maintained after a median 5 years' follow-up (hazard ratio 0.73; 95% CI 0.57-0.92; p=0.008) [Martin et al. ESMO 2017]. At both time-points, marked benefit with neratinib was evident in patients with hormone receptor (HR)+ tumors, whereas in patients with HR– disease, initial improvements with neratinib diminished after completing treatment. We report exploratory analyses from the ExteNET trial done to better characterize the effects of neratinib in the HR+ subgroup.

Methods: Patients with early-stage HER2+ BC were randomly assigned to oral neratinib 240 mg/day or placebo for 1 year after standard primary therapy and trastuzumab-based adjuvant therapy. Randomization was stratified by HR status (locally assessed), nodal status, and trastuzumab regimen. Adjuvant endocrine therapy was recommended for patients with HR+ disease. Data concerning disease recurrences were collected prospectively during year 1-2 post-randomization, and from medical records during year 3–5 post-randomization. Primary endpoint: iDFS. Secondary endpoints: DFS including ductal carcinoma in situ (DFS-DCIS); time to distant recurrence (TTDR); distant DFS (DDFS); cumulative incidence of central nervous system (CNS) recurrences; overall survival (OS). Hazard ratios (95% CI) were estimated using Cox proportional-hazards models. Data cut-off: March 2017. Clinicaltrials.gov: NCT00878709.

Results: 2840 patients were randomized (neratinib, n=1420; placebo, n=1420); 1631 (57%) patients had HR+ tumors (neratinib, n=816; placebo, n=815). 93% and 94% of HR+ patients in the neratinib and placebo groups, respectively, were receiving adjuvant endocrine therapy at baseline. Efficacy outcomes in the HR+ cohort after a median follow-up of 5.2 years are shown in the table. In subgroup analyses of the HR+ cohort, hazard ratios for iDFS were 0.49 in centrally confirmed HER2+ patients (n=951), and 0.58 in patients who had completed prior trastuzumab ≤12 months before randomization (n=1334). CNS recurrence and OS data are not yet mature.

 Updated 2-year analysis5-year analysis  Hazard ratiobP-value Hazard ratiobP-value Δ, %a(95% CI)(2 sided)Δ, %a(95% CI)(2 sided)iDFS4.10.49 (0.31–0.75)0.0014.40.60 (0.43–0.83)0.002DFS-DCIS4.80.45 (0.29–0.69)&lt;0.0015.10.57 (0.42–0.79)&lt;0.001DDFS3.10.52 (0.32–0.84)0.0084.00.60 (0.42–0.85)0.004TTDR2.90.52 (0.31–0.85)0.013.80.61 (0.42–0.86)0.006a. Difference in event rates between neratinib vs placebo; b. Neratinib vs placebo

Conclusions: Neratinib was associated with an absolute iDFS benefit of 4.4% in patients with HR+/HER2+ BC after 5 years' follow-up. HR/HER2 receptor cross-talk may underpin the notable effect of neratinib in patients with HR+ tumors when given in combination with endocrine therapy.

Citation Format: Chia SKL, Martin M, Iwata H, Moy B, Lalani AS, Holmes FA, Mansi J, von Minckwitz G, Buyse M, Delaloge S, Ejlertsen B, Yao B, Murias Rosales A, Hellerstedt B, Cold S, Inoue K, Shen Z-Z, Galeano T, Barrios CH, Chan A. Effects of neratinib after trastuzumab-based adjuvant therapy in hormone receptor-positive HER2+ early-stage breast cancer: Exploratory analyses from the phase III ExteNET trial [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 P1-13-03.

Abstract PD3-12: PIK3CA alterations and benefit with neratinib after trastuzumab-based adjuvant therapy in early-stage HER2+ breast cancer: Correlative analyses of the phase III ExteNET trial

Background: Neratinib is a pan-HER tyrosine kinase inhibitor that blocks the PI3K/Akt and MAPK signaling pathways downstream from HER2. The international, randomized, placebo-controlled phase III ExteNET trial showed that a 1-year course of neratinib after trastuzumab-based adjuvant therapy significantly improved 2-year invasive disease-free survival (iDFS) in early-stage HER2+ breast cancer (HR 0.67; 95% CI 0.50–0.91; p=0.0091) [Chan et al. Lancet Oncol 2016]. Furthermore, the effects of neratinib on iDFS were shown to be durable at 5 years' follow-up (HR 0.73; 95% CI 0.57–0.92; p=0.008) [Martin et al. ESMO 2017]. PIK3CA alterations are common in HER2+ breast cancers, and in general are associated with a worse prognosis. We sought to assess the prognostic and predictive significance of PIK3CA alterations in an exploratory substudy of the ExteNET trial.

Methods: ExteNET is an international, multi-center, randomized, double-blind, placebo-controlled phase III trial (Clinicaltrials.gov: NCT00878709). Patients received oral neratinib 240 mg/day or placebo for 1 year. Of the intent-to-treat (ITT) population (n=2840), primary formalin-fixed paraffin-embedded (FFPE) tumor specimens were available from 991 patients for PIK3CA mutation testing by RT-PCR for two hot-spot mutations in exon 9 (E542K, E545K/D) and one hot-spot mutation in exon 20 (H1047R). 702 FFPE tumor slides underwent FISH analysis for PIK3CA amplification with a ratio of ≥2.2 considered as amplified. Primary endpoint: iDFS. iDFS events were tested by 2-sided log-rank tests, and HR (95% CI) were estimated using Cox proportional-hazards models. Data cut-off: March 2017.

Results: Baseline demographics and disease characteristics between treatment arms of the correlative cohort (n=1201) were balanced. Overall, 21.2% (n=210) of primary tumors harbored one of the specified PIK3CA mutations, and 8.7% (n=61) were PIK3CA FISH-amplified. Patients with PIK3CA-altered tumors (i.e. PIK3CA mutations or FISH-amplified) had fewer iDFS events with neratinib compared with placebo (HR 0.41; 95% CI 0.17-0.90, p=0.028). The interaction test was not significant (p=0.1842). Results of the various correlative analyses within treatment arms are shown in the table.

 NeratinibPlacebo   iDFS iDFS 2-sidedPopulationnevents, nnevents, nHR (95% CI)P valueaITT142011614201630.73 (0.57–0.92)b0.008bCorrelative cohort59345608700.67 (0.45–0.96)0.0317PIK3CA-mutation positive1047106170.43 (0.17–1.01)0.056PIK3CA-mutation negative38527396420.66 (0.40-1.06)0.089PIK3CA-amplified3312840.20 (0.01-1.33)0.106PIK3CA-non-amplified31629325360.85 (0.52-1.39)0.521PIK3CA-altered1308132200.41 (0.17-0.90)0.028a. Log-rank test; b. Stratified analysis

Conclusions: One year of neratinib treatment after trastuzumab-based adjuvant therapy significantly improves iDFS after 5 years in patients with early-stage HER2+ breast cancer. From this modest-sized exploratory cohort, it appears that PIK3CA may be a biomarker for differential sensitivity to neratinib after 1 year of trastuzumab in the adjuvant setting.These exploratory results should be validated in a larger subset.

Citation Format: Chia SKL, Martin M, Holmes FA, Ejlertsen B, Delaloge S, Moy B, Iwata H, von Minckwitz G, Mansi J, Barrios CH, Gnant M, Tomašević Z, Denduluri N, Šeparović R, Kim S-B, Hugger Jakobsen E, Harvey V, Robert N, Smith II J, Harker G, Lalani AS, Zhang B, Eli LD, Buyse M, Chan A. PIK3CA alterations and benefit with neratinib after trastuzumab-based adjuvant therapy in early-stage HER2+ breast cancer: Correlative analyses of the phase III ExteNET trial [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 PD3-12.

Neratinib after trastuzumab-based adjuvant therapy in HER2-positive breast cancer (ExteNET): 5-year analysis of a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

ExteNET showed that 1 year of neratinib, an irreversible pan-HER tyrosine kinase inhibitor, significantly improves 2-year invasive disease-free survival after trastuzumab-based adjuvant therapy in women with HER2-positive breast cancer. We report updated efficacy outcomes from a protocol-defined 5-year follow-up sensitivity analysis and long-term toxicity findings.

METHODS

In this ongoing randomised, double-blind, placebo-controlled, phase 3 trial, eligible women aged 18 years or older (≥20 years in Japan) with stage 1-3c (modified to stage 2-3c in February, 2010) operable breast cancer, who had completed neoadjuvant and adjuvant chemotherapy plus trastuzumab with no evidence of disease recurrence or metastatic disease at study entry. Patients who were eligible patients were randomly assigned (1:1) via permuted blocks stratified according to hormone receptor status (hormone receptor-positive vs hormone receptor-negative), nodal status (0 vs 1-3 vs or ≥4 positive nodes), and trastuzumab adjuvant regimen (given sequentially vs concurrently with chemotherapy), then implemented centrally via an interactive voice and web-response system, to receive 1 year of oral neratinib 240 mg/day or matching placebo. Treatment was given continuously for 1 year, unless disease recurrence or new breast cancer, intolerable adverse events, or consent withdrawal occurred. Patients, investigators, and trial funder were masked to treatment allocation. The predefined endpoint of the 5-year analysis was invasive disease-free survival, analysed by intention to treat. ExteNET is registered with ClinicalTrials.gov, number NCT00878709, and is closed to new participants.

FINDINGS

Between July 9, 2009, and Oct 24, 2011, 2840 eligible women with early HER2-positive breast cancer were recruited from community-based and academic institutions in 40 countries and randomly assigned to receive neratinib (n=1420) or placebo (n=1420). After a median follow-up of 5·2 years (IQR 2·1-5·3), patients in the neratinib group had significantly fewer invasive disease-free survival events than those in the placebo group (116 vs 163 events; stratified hazard ratio 0·73, 95% CI 0·57-0·92, p=0·0083). The 5-year invasive disease-free survival was 90·2% (95% CI 88·3-91·8) in the neratinib group and 87·7% (85·7-89·4) in the placebo group. Without diarrhoea prophylaxis, the most common grade 3-4 adverse events in the neratinib group, compared with the placebo group, were diarrhoea (561 [40%] grade 3 and one [<1%] grade 4 with neratinib vs 23 [2%] grade 3 with placebo), vomiting (grade 3: 47 [3%] vs five [<1%]), and nausea (grade 3: 26 [2%] vs two [<1%]). Treatment-emergent serious adverse events occurred in 103 (7%) women in the neratinib group and 85 (6%) women in the placebo group. No evidence of increased risk of long-term toxicity or long-term adverse consequences of neratinib-associated diarrhoea were identified with neratinib compared with placebo.

INTERPRETATION

At the 5-year follow-up, 1 year of extended adjuvant therapy with neratinib, administered after chemotherapy and trastuzumab, significantly reduced the proportion of clinically relevant breast cancer relapses-ie, those that might lead to death, such as distant and locoregional relapses outside the preserved breast-without increasing the risk of long-term toxicity. An analysis of overall survival is planned after 248 events.

FUNDING

Wyeth, Pfizer, and Puma Biotechnology.

Anxiety in breast cancer patients treated with neoadjuvant therapy: Effects on surgical plan and role of supportive care

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Background: The impact of high anxiety on surgical decision making has been demonstrated in various cancer settings. For patients undergoing neoadjuvant therapy (NAT) for breast cancer, supportive services can be offered prior to surgery and may help them choose between the options of bilateral mastectomy, unilateral mastectomy, or breast conserving surgery (BCS) where clinically appropriate. However, the effect of anxiety at initial diagnosis and psychological support on these decisions has not yet been studied. Methods: A prospective database of breast cancer patients treated with NAT at the British Columbia Cancer Agency was utilized to extract demographic information, surgical plan with regards to BCS and unilateral or bilateral mastectomy, and information about supportive services utilized. This was correlated with anxiety scores at initial consultation recorded by the Edmonton Symptom Assessment System and the Psychosocial Screen for Cancer. Patients were excluded if they had bilateral breast cancer, BRCA mutation, or missing data. Fisher’s exact tests were applied for statistical analysis. Results: From 2012-2016, 361 potential patients were identified. In total, 203 patients met eligibility criteria: 93 patients (46%) had low anxiety and 110 patients (54%) had high anxiety. Patients with high self-reported anxiety at initial consultation were 19% more likely to undergo aggressive surgery (bilateral mastectomy for unilateral disease or mastectomy for BCS eligible disease) than those with low self-reported anxiety at initial consultation (37% VS 18%; p = 0.003). Of the 110 patients with high anxiety, only 46 patients (42%) utilized counselling before surgery. No significant difference in rate of aggressive surgery was observed in patients with high anxiety who had counselling compared to those who did not (33% VS 41%; p = 0.43). Conclusions: High anxiety at initial consultation is associated with a 19% increase in aggressive surgery compared to patients with low anxiety. Counselling resources are currently underutilized by eligible patients, but this did not have an impact on surgical decision making in this study. This may be an area of opportunity for further research.

Treat ER+ight: Canadian prospective observational study in post-menopausal HR+HER2- advanced breast cancer women—First interim analysis (IA)

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Background: Treat ER+ight is the first Canadian real-world study enrolling patients (pts) previously exposed to NSAI therapy and currently receiving endocrine therapy (ET) alone or in combination with targeted therapy (ET+TT). Methods: This first planned IA describes baseline parameters and adverse event (AE) prevention strategies adopted by 16 centers since Feb 2016 upon enrolling pts initiating ET or ET+TT. Results: See Table.Conclusions: This IA suggests that pts initiating ET+TT are younger, have a better ECOG status, mostly visceral disease and receive more prophylactic/proactive AE prevention therapies. Insights into real-world dosing and sequence will be presented. Clinical trial information: NCT02753686. [Table: see text]

Neratinib after trastuzumab-based adjuvant therapy in patients with HER2-positive breast cancer (ExteNET): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Neratinib, an irreversible tyrosine-kinase inhibitor of HER1, HER2, and HER4, has clinical activity in patients with HER2-positive metastatic breast cancer. We aimed to investigate the efficacy and safety of 12 months of neratinib after trastuzumab-based adjuvant therapy in patients with early-stage HER2-positive breast cancer.

METHODS

We did this multicentre, randomised, double-blind, placebo-controlled, phase 3 trial at 495 centres in Europe, Asia, Australia, New Zealand, and North and South America. Eligible women (aged ≥18 years, or ≥20 years in Japan) had stage 1-3 HER2-positive breast cancer and had completed neoadjuvant and adjuvant trastuzumab therapy up to 2 years before randomisation. Inclusion criteria were amended on Feb 25, 2010, to include patients with stage 2-3 HER2-positive breast cancer who had completed trastuzumab therapy up to 1 year previously. Patients were randomly assigned (1:1) to receive oral neratinib 240 mg per day or matching placebo. The randomisation sequence was generated with permuted blocks stratified by hormone receptor status (hormone receptor-positive [oestrogen or progesterone receptor-positive or both] vs hormone receptor-negative [oestrogen and progesterone receptor-negative]), nodal status (0, 1-3, or ≥4), and trastuzumab adjuvant regimen (sequentially vs concurrently with chemotherapy), then implemented centrally via an interactive voice and web-response system. Patients, investigators, and trial sponsors were masked to treatment allocation. The primary outcome was invasive disease-free survival, as defined in the original protocol, at 2 years after randomisation. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00878709.

FINDINGS

Between July 9, 2009, and Oct 24, 2011, we randomly assigned 2840 women to receive neratinib (n=1420) or placebo (n=1420). Median follow-up time was 24 months (IQR 20-25) in the neratinib group and 24 months (22-25) in the placebo group. At 2 year follow-up, 70 invasive disease-free survival events had occurred in patients in the neratinib group versus 109 events in those in the placebo group (stratified hazard ratio 0·67, 95% CI 0·50-0·91; p=0·0091). The 2-year invasive disease-free survival rate was 93·9% (95% CI 92·4-95·2) in the neratinib group and 91·6% (90·0-93·0) in the placebo group. The most common grade 3-4 adverse events in patients in the neratinib group were diarrhoea (grade 3, n=561 [40%] and grade 4, n=1 [<1%] vs grade 3, n=23 [2%] in the placebo group), vomiting (grade 3, n=47 [3%] vs n=5 [<1%]), and nausea (grade 3, n=26 [2%] vs n=2 [<1%]). QT prolongation occurred in 49 (3%) patients given neratinib and 93 (7%) patients given placebo, and decreases in left ventricular ejection fraction (≥grade 2) in 19 (1%) and 15 (1%) patients, respectively. We recorded serious adverse events in 103 (7%) patients in the neratinib group and 85 (6%) patients in the placebo group. Seven (<1%) deaths (four patients in the neratinib group and three patients in the placebo group) unrelated to disease progression occurred after study drug discontinuation. The causes of death in the neratinib group were unknown (n=2), a second primary brain tumour (n=1), and acute myeloid leukaemia (n=1), and in the placebo group were a brain haemorrhage (n=1), myocardial infarction (n=1), and gastric cancer (n=1). None of the deaths were attributed to study treatment in either group.

INTERPRETATION

Neratinib for 12 months significantly improved 2-year invasive disease-free survival when given after chemotherapy and trastuzumab-based adjuvant therapy to women with HER2-positive breast cancer. Longer follow-up is needed to ensure that the improvement in breast cancer outcome is maintained.

FUNDING

Wyeth, Pfizer, Puma Biotechnology.

Invasive disease-free survival benefit following neratinib as extended adjuvant therapy in centrally-confirmed HER2+ early-stage breast cancer: The ExteNET phase III randomized placebo-controlled trial

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Background: Neratinib is an irreversible pan-HER tyrosine kinase inhibitor with clinical efficacy in trastuzumab pre-treated HER2-positive (HER2+) metastatic breast cancer (BC). ExteNET is an ongoing multicenter randomized placebo-controlled phase III trial evaluating the efficacy and safety of a 1-year course of neratinib in patients with early-stage HER2+ BC after trastuzumab-based adjuvant therapy (clinicaltrials.gov: NCT00878709). Methods: Women with locally-confirmed early-stage HER2+ BC were randomly assigned to oral neratinib 240mg/day or matching placebo for 1 year. Archived diagnostic tumor samples were submitted for HER2 gene amplification testing at a central laboratory. Primary endpoint: invasive disease-free survival (iDFS). Secondary endpoints: DFS including ductal carcinoma in situ (DFS+DCIS); distant disease-free survival (DDFS); time to distant recurrence (TDR). Stratified Cox proportional-hazards models were used to estimate hazard ratios (HR) for the ITT and amended ITT (aITT) populations; unstratified models were used for the centrally confirmed HER2 population. Treatment groups were compared using 2-sided log-rank tests. Results: The ITT population included 2840 patients (neratinib, N=1420; placebo, N=1420). The higher-risk aITT population (i.e. node-positive disease and randomized ≤1 year of completing prior trastuzumab) included 1873 patients (neratinib, N=938; placebo, N=935). Of the tumor samples analyzed, 1463 (86%) were centrally confirmed (neratinib, N=741; placebo, N=722). Conclusions: Neratinib significantly improves iDFS in trastuzumab-treated early-stage HER2+ BC patients. An enhanced treatment effect is observed with neratinib in women with centrally confirmed HER2+ tumors. Clinical trial information: NCT00878709. [Table: see text]

Correlation between Nottingham grade and Oncotype DX score in breast cancer: Implications for cost-effective incorporation of oncotype in the clinic

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Background: Nottingham grading (NG) for breast cancer uses tubule formation (TF), nuclear polymorphism (NP), and mitotic count (MC). The Oncotype Dx recurrence score (RS) is a 21-gene assay that predicts recurrence. Both NG and RS can influence decisions about the use of adjuvant chemotherapy in patients with ER+, HER2-, T1-T2, N0 cancers. The objective was to determine the correlation of overall NG, TF, NP, MC with RS risk group in such patients. This may be useful in guiding the use of Oncotype in specific cases. Methods: 231 patients referred to the BC Cancer Agency between 2007-2011 with ER+, HER2-, T1-T2, N0 breast cancer and an Oncotype were identified. Histologic grading was assessed on the specimen used for Oncotype. Spearman’s correlation coefficients, and 95% confidence intervals (CI) were calculated for the RS risk group versus overall NG, TF, NP, and MC. This study adds to the literature as it is one of the largest cohorts examining this topic and focuses on a HER2- patient population. Results: There was a significant positive moderate correlation between RS and overall grade (Spearman coefficient 0.47, [95%CI: 0.36, 0.56])(Table 1), and RS and MC (Spearman 0.44, [95%CI: 0.33, 0.54]). There was a significant positive weak correlation between RS and TF (Spearman 0.25, [95%CI: 0.13, 0.37]) and RS and NP (Spearman 0.34, [95%CI: 0.22, 0.45]). None of the patients with low overall NG had a high risk RS. Conclusions: Patients with a low NG are unlikely to have a high risk RS (0 in 231 patients) and very few such patients would benefit from the expense of an Oncotype. Overall NG has a better correlation with RS than TF, MC, or NP components alone. [Table: see text]

Randomised, phase II, placebo-controlled, trial of fulvestrant plus vandetanib in postmenopausal women with bone only or bone predominant, hormone-receptor-positive metastatic breast cancer (MBC): the OCOG ZAMBONEY study

Biomarkers of bone turnover, including urine N-telopeptide (uNTx), have been used as surrogate measures of response to bone-targeted therapies. Vascular endothelial growth factor (VEGF) levels correlate with extent of bone metastases. We assessed whether vandetanib, an inhibitor of VEGF, epidermal growth factor receptor and RET signalling, improved uNTx response when added to fulvestrant (F) in breast cancer patients with bone metastases. Postmenopausal patients with bone predominant, hormone-receptor-positive metastatic breast cancer were randomised to F (500 mg IM days 1, 15, 29, then monthly) with either vandetanib (100 mg PO OD) (FV) or placebo (FP). The primary objective was uNTx response. Secondary objectives included PFS, OS, RECIST response, pain scores and toxicity. Sixty-one patients were allocated to FV and 68 to FP. Out of 127 analyzable patients, an uNTx response occurred in 66 % for FV and 54 % for FP (p = 0.21). No difference was detected between groups for PFS; HR = 0.95 (95 % CI 0.65-1.38) or OS HR = 0.69 (95 % CI 0.37-1.31). For the 62 patients with measurable disease, clinical benefit rates were 41 and 43 %, respectively (p = 0.47). Serious adverse events were similar, 3.3 % for FV versus 5.9 % for FP. Elevated baseline uNTx (>65 nM BCE/mmol Cr) was prognostic for PFS, HR = 1.55 (95 % CI 1.04-2.30) and for OS, HR = 2.32 (95 % CI 1.25-4.33). The addition of vandetanib to fulvestrant did not improve biomarker response, PFS or OS in patients with bone metastases. Baseline bone turnover was prognostic for PFS and OS.