Impact of anti-HER2 therapy alone and in association with weekly paclitaxel on the ovarian reserve of young women with HER2-positive early breast cancer: Biomarker analysis of the NeoALTTO trial

12084

Background: The potential gonadotoxicity of anti-HER2 agents remains largely unknown and limited conflicting evidence exists for taxanes. Anti-Mullerian hormone (AMH) is an established biomarker of ovarian reserve; its measurement during systemic therapies may aid in indicating gonadotoxicity, in the diagnosis and prediction of primary ovarian insufficiency (POI). The present analysis explored for the first time the impact of anti-HER2 therapy alone and then combined with weekly paclitaxel on ovarian reserve measured by AMH levels in breast cancer (BC) patients not previously exposed to anthracycline and cyclophosphamide. Methods: This biomarker analysis of the NeoALTTO (NCT00553358) randomized phase III neoadjuvant trial included premenopausal women aged ≤45 years at diagnosis of HER2-positive early BC with available frozen serum samples at baseline (i.e. before administering any anticancer treatment), at week 2 (i.e. “biological window” of anti-HER2 therapy alone) and/or at the time of surgery (i.e. after completion of paclitaxel plus anti-HER2 therapy and before starting adjuvant chemotherapy). Central AMH testing was performed with the Roche Elecsysâ AMH Plus assay (LoD = 0.01 ng/ml). AMH levels during anti-HER2 therapy alone and then combined with paclitaxel were assessed as a measure of treatment acute gonadotoxicity. The impact of different anti-HER2 agents, patients’ age, and baseline AMH levels on treatment gonadotoxicity were also investigated. Results: The present analysis included 130 patients with a median age of 38 years (IQR: 33-42 years). AMH values at the 3 time points differed significantly from each other (p < 0.001). At baseline, median AMH levels were 1.29 ng/mL (IQR 0.56 – 2.62 ng/mL). At week 2, a small but significant reduction in AMH levels was observed (median value: 1.10 ng/mL, IQR 0.45 – 2.09 ng/mL, p < 0.001). At surgery, there was a larger significant decline in AMH levels (median value: 0.01 ng/mL, IQR 0.01 – 0.03 ng/mL, p < 0.001). There was no significant difference between treatment arms (trastuzumab vs. lapatinib vs. trastuzumab plus lapatinib) in the degree of reduction in AMH levels at week 2 (p = 0.763) and at surgery (p = 0.700). Age and pre-treatment ovarian reserve had a major influence on treatment-induced gonadotoxicity risk, with older age and lower AMH levels at diagnosis being associated with a greater negative impact. Conclusions: This biomarker analysis of the NeoALTTO trial showed for the first time that anti-HER2 therapies alone had limited gonadotoxicity but the addition of weekly paclitaxel resulted in marked AMH decline which likely has implications for subsequent ovarian function and fertility. These data highlight the importance of oncofertility counselling among all premenopausal women with HER2-positive BC receiving systemic anticancer treatments. Clinical trial information: NCT00553358.

Impact of cancer diagnosis, stage, and systemic therapies on immunogenicity after COVID-19 vaccination in patients with cancer: A systematic review and meta-analysis

1537

Background: Patients (pts) with cancer are at increased risk of severe COVID-19. Both underlying malignancy and anti-cancer treatments influence the immune system, potentially impacting the level of vaccine protection achieved. Methods: A systematic literature search of PubMed, Embase, CENTRAL and conference proceedings (ASCO annual meetings and ESMO congress) up to 28/09/21, was conducted to identify studies reporting anti-SARS-CoV-2 spike protein immunoglobulin G seroconversion rates (SR) at any time point after complete COVID-19 immunization (mRNA- or adenoviral-based vaccines) in cancer pts. Complete immunization was defined as 1 dose of JNJ-78436735 vaccine or 2 doses of BNT162b2, mRNA-1273 or ChAdOx1 nCoV-19 vaccines. Subgroup analyses were performed to examine the impact of cancer diagnosis, disease stage, and anticancer therapies on the SR. Overall effects were pooled using random-effects models and reported as pooled SR with 95% confidence intervals (CI). Results: Of 1,548 identified records, 64 studies were included in this analysis reporting data from 10,511 subjects. The Table shows the SR in the overall population and specific subgroups. In pts with solid malignancies (SM), disease stage and primary site did not significantly impact the SR. In pts with hematologic malignancies (HM), SR were significantly lower in pts with chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL) compared to acute lymphoblastic leukemia (ALL), Hodgkin lymphoma (HL), and multiple myeloma (MM). Concerning the impact of cancer therapies on SR, pts with SM undergoing chemotherapy had numerically lower SR (N = 1,234, SR 87%, CI 81-92) compared to those treated with immune checkpoint inhibitors (N = 574, SR 94%, CI 88-97) or endocrine therapy (N = 326, SR 94%, CI 86-97) with or without another targeted therapy. Pts with HM treated with anti-CD20 therapy (within the last 12 months: N = 360, SR 7%, CI 2-20; or more than 12m: N = 175, SR 59%, CI 35-80), immune-modulating agents (BTK or BCL2 inhibitors) (N = 462, SR 47%, CI 32-64%) or other immunotherapies (anti-CD19/CART or anti-CD38) (N = 293, SR 37%, CI 23-53) had lower SR compared to pts treated with autologous (N = 353, SR 77%, CI 67-85) or allogenic stem cell transplantation (N = 509, SR 77%, CI 68-84). Conclusions: SR varies between cancer types and anticancer therapies with some cancer pts having low protection against COVID-19 even after complete vaccination. [Table: see text]

Sacituzumab govitecan (SG) versus treatment of physician’s choice (TPC) in patients (pts) with previously treated, metastatic triple-negative breast cancer (mTNBC): Final results from the phase 3 ASCENT study

1071

Background: Treatment goals for pts with metastatic breast cancer include extended survival and improved quality of life (QoL). SG is an antibody-drug conjugate composed of an anti–Trop-2 antibody coupled to the cytotoxic SN-38 payload via a proprietary, hydrolyzable linker. SG received FDA approval for pts with mTNBC who received ≥2 prior chemotherapies (at least 1 in the metastatic setting). In the pivotal phase 3 ASCENT study (NCT02574455), SG demonstrated a significant survival benefit over single-agent chemotherapy TPC in the primary analysis population of pts with second line or greater (2L+) mTNBC without known brain metastases at baseline (Bardia A et al. NEJM 2021) and QoL (Loibl S. et al. ESMO 2021). With additional follow up, we present the final data on efficacy, including overall survival (OS), safety, and QoL. Methods: Pts with mTNBC refractory or relapsing after ≥2 prior chemotherapies with at least 1 in the metastatic setting were randomized 1:1 to receive SG (10 mg/kg IV on days 1 and 8, every 21 days) or TPC (capecitabine, eribulin, vinorelbine, or gemcitabine) until disease progression or unacceptable toxicity. Primary endpoint was progression-free survival (PFS) per RECIST 1.1 by independent review in pts without known brain metastases at baseline. Key secondary endpoints included OS, safety, and health-related QoL. Safety was analyzed in pts who received ≥1 dose of study drug. Results: Of 529 pts enrolled, 468 did not have known brain metastases at baseline (median age: 54 y [range, 27-82]; median prior lines: 4 [range, 2-17]). As of Feb 25, 2021 (final database lock), SG (n = 235) vs TPC (n = 233) significantly improved median PFS (5.6 vs 1.7 mo; HR: 0.39; P< 0.0001) and median OS (12.1 vs 6.7 mo; HR: 0.48; P< 0.0001). The OS rate at 24 months was 22.4% (95% CI, 16.8-28.5) in the SG arm and 5.2% (95% CI, 2.5-9.4) in the TPC arm. In the safety population (n = 482), key treatment-related grade ≥3 adverse events with SG (n = 258) vs TPC (n = 224) were diarrhea (11% vs 0.4%), neutropenia (52% vs 33%), anemia (8% vs 5%), and febrile neutropenia (6% vs 2%). There was no grade ≥3 neuropathy and 1 case of grade 3 interstitial lung disease reported with SG. No patient experienced a treatment-related death with SG, and there was 1 treatment-related death with TPC due to neutropenic sepsis. Treatment discontinuations due to AEs were ≤3% in both arms. SG arm showed clinically meaningful and statistically significant improvements than the TPC arm in scores for all five primary focus health-related QoL domains. Conclusions: The analysis based on the final database lock of ASCENT confirms the superior survival outcomes of SG over single-agent chemotherapy, with a manageable safety profile and improvement in QoL for pts with mTNBC in the 2L+ setting. These findings reinforce SG as an effective treatment option for this pt population. Clinical trial information: NCT02574455.

Effect of mevalonate pathway inhibitors on outcomes of patients (pts) with HER2-positive early breast cancer (BC) in the ALTTO trial

522

Background: Our preclinical findings suggest a role for the mevalonate pathway (MVA) in treatment resistance in HER2+ BC by providing alternative growth and survival signaling to bypass potent HER2 blockade, which could be overcome by the MVA inhibitors statins and nitrogen-containing bisphosphonates (NBs). Here we explored the effect of MVA inhibitors’ use on pts’ outcomes in the ALTTO trial (BIG2-06; NCT00490139). Methods: In the ALTTO trial, 8381 pts with HER2+ BC were randomized to 1 year of adjuvant lapatinib (L), trastuzumab (T), L+T, or T→L. All pts with documented treatment start with statins or NBs < 1 year after randomization were considered as MVA inhibitors users. Survival curves, with a median follow-up of 6.9 years, for disease-free survival (DFS), distant relapse-free interval (DRFI), BC-specific survival (BCSS), and overall survival (OS) according to MVA inhibitors use were estimated by the Kaplan Meier method and Log-rank test. All multivariate survival analyses employed a Cox proportional hazards regression model, adjusting for tumor size, nodal status, hormonal receptor (HoR), menopausal status, BMI, timing of chemo, and randomization arm. We considered interactions terms in Cox’s model between MVA inhibitors use and randomization arm, hormonal status, and BMI group. Results: Among the 8381 pts included in this study, 493 and 299 were statins or NBs users, respectively. Table 1 summarizes the significant differences in pts’ characteristics according to MVA inhibitors use ( P <.005). In multivariate survival analyses, only NBs use was associated independently with better BCSS (HR, 0.44; 95% CI, 0.23 - 0.84; P = 0.014). Statin use was not independently associated with prognosis but only in interaction with pts characteristics: worse DFS, BCSS and OS in pts treated with L+T, worse DRFI and OS in pts treated with HoR+ BC (respective interaction P-values <0.05 in the Cox’s model). Conclusions: NBs independently predicted improved BC-specific outcome in pts with HER2+ BC treated with adjuvant anti-HER2 therapy. Statin use was associated with an inferior outcome in pts with HoR+ disease and/or those treated with L+T. Whether this inferior association in statin users may reflect the underlying predisposition factors that can weaken the efficacy of anti-HER2 treatments and whether this effect was observed only in the L+T arm due to the more potent inhibition of the HER2 signaling pathway remain open questions. Further clinical investigations on the impact of MVA inhibitors on the outcome of pts with HER2+ BC are warranted. [Table: see text]

Demographic and laboratory determinants of humoral immune responses and impact of different anti-SARS-CoV-2 vaccine platforms in patients with cancer: A systematic review and meta-analysis

1543

Background: Patients (pts) with cancer have increased mortality from COVID-19 and their vaccination is crucial to prevent severe infection. We aimed to identify demographic and laboratory determinants of humoral immune responses to COVID-19 vaccination in pts with cancer and investigate differences in responses based on the vaccine platform. Methods: We searched for records in PubMed, Embase, and CENTRAL up to 28/09/21, as well as conference proceedings from ASCO and ESMO 2021. We included studies of pts ≥16 yr with a cancer diagnosis, who were vaccinated against SARS-CoV-2. Studies were excluded if ≥10% of the participants had other causes of immunosuppression or baseline anti-SARS-CoV-2 spike protein antibodies (Ab)/previous COVID-19 (PROSPERO ID: CRD42021282338). For this subgroup analysis of studies that reported a proportion of pts with cancer and positive Ab titers at any timepoint following complete vaccination, a random-effects model was used to estimate the humoral response rate (HRR) with 95% confidence intervals (CI). Results: We included 64 records, reporting data from 10,511 cancer pts. The HRR in the overall population and by subgroup are shown in Table. Elder patients with hematologic cancers (59%, CI 47-70%, N = 667) and patients with lymphopenia (50%, CI 25-75%, N = 111) or hypogammaglobulinemia (36%, CI 19-57%, N=226) were the subgroups with lower HRR. Male (77%, CI 69-84%, N = 2,659) and Asian (84%, CI 54-96%, N = 37) pts showed a trend to lower HRR when compared with females and other races, respectively. Pts vaccinated with mRNA vaccine platforms (79%, CI 74-83%, N = 9,404) had numerically higher HRR than those receiving the adenovirus vaccines (28%, CI 19-40%, N = 74). Conclusions: This study highlights demographic and laboratory determinants of weaker immune responses to SARS-CoV-2 vaccination, permitting better identification of more vulnerable pts. Despite the small number of pts included receiving adenovirus vaccines, these data also suggest prioritizing mRNA platform vaccination in pts with cancer. [Table: see text]

DECRESCENDO: De-escalation of adjuvant chemotherapy in patients with HER2+/HR-/node-negative early breast cancer who achieve pCR after neoadjuvant taxane and subcutaneous dual anti-HER2 blockade

TPS621

Background: Human Epidermal growth factor Receptor-2 positive (HER2+) breast cancer (BC) heterogeneity can be captured at the mRNA level by the PAM50 classification. The HER2 “Enriched” (HER2-E) intrinsic subtype is encountered more often in HER2+ Hormone Receptor negative (HR-) tumors compared to HER2+ HR+ tumors and is particularly sensitive to HER2 blockade. HER2+ HR- and HER2-E achieve high pathological complete response (pCR) rates with neoadjuvant chemotherapy (CT) and dual anti-HER2 blockade with trastuzumab and pertuzumab. Additionally, the patients with pCR have improved outcomes. However, standard CT with common drugs such as anthracyclines has significant short and long-term toxicities, including cardiac events and secondary leukemias. Thus, tailoring the neoadjuvant treatment among carefully selected patients in order to reduce toxicity while preserving efficacy is a priority in early HER2-positive BC. Methods: DECRESCENDO is a large, multicentric, single-arm, phase 2 de-escalation study evaluating the efficacy of neoadjuvant CT with paclitaxel 80mg/m2 weekly or docetaxel 75mg/m2 every 3 weeks (Q3W) with pertuzumab and trastuzumab (P+T) 600/600mg fixed-dose combination (FDC) for subcutaneous (SC) injection Q3W for patients with early HER2+, HR- (ER<1% and PR<1%) BC. After surgery, the patients with pCR (defined as Residual Cancer Burden (RCB)=0, per local assessment) will receive 14 additional cycles of P+T FDC SC. Patients with RCB≥1 will receive adjuvant T-DM1 (preceded by anthracycline-based CT if RCB≥2). Eligible patients must be candidates for neoadjuvant treatment, with a tumor between 15 and 50mm, N0, ECOG PS 0-1, with LVEF ≥55%. 1,065 patients will be enrolled in 12 countries. A baseline tumor sample is required to retrospectively assess the intrinsic tumor subtype. The primary objective is to evaluate 3-year recurrence-free survival (RFS) in patients with HER2-E tumors who achieve pCR after neoadjuvant treatment. The key secondary objective is to evaluate 3-year RFS in all patients with pCR. If a 3-year RFS ≥94% with the lower boundary of a 1-sided 95% CI ≥92% is observed in the target group, the study treatment will be considered an acceptable alternative to strategies that include the addition of other chemotherapies such as anthracyclines, alkylating agents and platinum salts. A flexible care sub-study will enroll 121 patients with pCR in Belgium, France, Ireland, Israel and Italy to receive adjuvant P+T FDC SC in a location outside the hospital, such as at home or workplace. The aim is to compare patient preference for administration of P+T FDC SC outside the hospital vs in the hospital. The first patient was enrolled in January 2022. The trial is co-led by the Breast International Group (BIG) and Institut Jules Bordet. Clinical trial information: NCT04675827.

Cardiac safety of dual anti-HER2 blockade with pertuzumab plus trastuzumab (P+T) in the APHINITY trial

510

Background: Trastuzumab (T) increases the incidence of cardiac events (CEs) in patients (pts) with early breast cancer (BC). Dual blockade with P+T improves BC outcomes and is the standard of care for high-risk HER2-positive BC pts following the phase 3 APHINITY trial that evaluated the addition of P or placebo (Pla) to T and chemotherapy (CT). We analyzed the cardiac safety of P+T in APHINITY. Methods: APHINITY eligibility required a left ventricular ejection fraction (LVEF) ≥55% at study entry. LVEF assessment was performed every 3 months (mos) during treatment, every 6 mos up to month 36, and yearly thereafter. Primary CE was defined as heart failure (HF) class III/IV and a significant decrease in LVEF of at least 10 percentage points from baseline and to <50%, or cardiac death. Secondary CE was defined as a confirmed significant decrease in LVEF or CEs confirmed by the cardiac advisory board. Results: The safety analysis population consists of 4,769 pts. With 74 mos median follow-up (FU), CEs were observed in 159 pts (3.3%): 83 (3.5%) in the P+T and 76 (3.2%) in Pla+T arms, respectively. Most CEs occurred during anti-HER2 therapy: 123/159 (77.4%) and were asymptomatic or mildly symptomatic LVEF decrease (133/159; 83.6%) (Table 1). There were 2 cardiac deaths in each arm (0.1%). More CEs occurred in pts receiving an anthracycline-based CT compared to those receiving non-anthracycline CT (139 vs. 20 CEs, respectively). Acute recovery from a CE based on subsequent LVEF values was observed in 127/155 pts (81.9%). Conclusions: Dual blockade with P+T does not increase the risk of CE compared to Pla+T alone. The use of anthracycline-based CT increases the risk of a CE; hence non-anthracycline CT may be considered particularly in pts with other cardiovascular risk factors. Clinical trial information: NCT01358877. [Table: see text]

Outcome of patients with an ultralow risk 70-gene signature in the MINDACT trial

500

Background: Gene signatures have proven successful in identifying patients with a low risk of distant recurrence who could forego chemotherapy (CT) and are currently included in international treatment guidelines for breast cancer. For the 70-gene signature (MammaPrint) an additional threshold was established within the low risk category to identify patients with an ultralow risk of distant recurrence. In independent cohorts, these patients had excellent breast cancer specific survival at 15 years, suggesting that ultralow risk cancers represent indolent disease (Esserman, JAMA Oncol 2017, Delahaye, BC Res Treat 2017). Here we evaluate survival of patients with an ultralow risk 70-gene signature who participated in the randomized phase 3 MINDACT trial (Piccart, Lancet Oncol 2021). Methods: Of the 6,693 patients enrolled in the MINDACT trial (EORTC 10041/BIG 3-04) between 2007-2011, profiling revealed an ultralow risk 70-gene signature in 1,000 patients (15%). We assessed 5- and 8-year distant metastasis free interval (DMFI) and breast cancer specific survival (BCSS) in patients stratified by 70-gene signature result (high, low, ultralow), and within the ultralow risk group stratified by clinical risk. For these exploratory analyses, we used Kaplan-Meier estimates for time to event endpoints and Cox-regression models to calculate hazard ratio’s (HR). Results: Median follow-up was 8.7 years. Among the ultralow risk patients (n = 1,000), 67% were ≥50 years, 81% had tumors < 2cm, 80% were lymph node negative, 96% had grade 1 or 2 tumors and 99% were ER-positive. Systemic therapy was received by 83% of patients (69% endocrine therapy (ET), 14% ET + CT) and 16% received no adjuvant systemic treatment (AST). Survival estimates for all endpoints are shown in the table; 8-year DMFI was 97.0% (95% CI 95.8-98.1) for ultralow risk. The 8-year DMFI in ultralow risk patients who received no AST or ET only was 97.8% (95% CI 95.3-100) and 97.4% (95% CI 96.1-98.7), respectively. The HR for DMFI was 0.66 (95% CI 0.46-0.95) for ultralow vs low risk, after adjusting for tumor and treatment characteristics (preliminary results). Conclusions: In this prospective study, patients with an ultralow risk 70-gene signature have an excellent prognosis with 8-year BCSS above 99% regardless of clinical risk status, and with an 8-year DMFI of 95-98%.[Table: see text]

Assessment of sacituzumab govitecan (SG) in patients with prior neoadjuvant/adjuvant chemotherapy in the phase 3 ASCENT study in metastatic triple-negative breast cancer (mTNBC)

1080

Background: mTNBC is a heterogenous disease with few treatment options and poor outcomes. Pts who recur ≤ 12 mo after completing (neo)adjuvant chemotherapy may represent a subset with more aggressive disease. SG is an antibody-drug conjugate composed of an anti–Trop-2 antibody coupled to the cytotoxic SN-38 payload via a proprietary, hydrolyzable linker. SG received accelerated approval for pts with mTNBC who received ≥ 2 prior therapies for metastatic disease; clinical benefit for SG over treatment of physician's choice (TPC) was confirmed in the phase 3 ASCENT study (NCT02574455) for median progression-free survival (PFS; 5.6 vs 1.7 mo), median overall survival (OS; 12.1 vs 6.7 mo), objective response rate (ORR; 35% vs 5%), clinical benefit rate (CBR; 45% vs 9%), and median duration of response (6.3 vs 3.6 mo). This ASCENT subanalysis of pts with mTNBC who recurred ≤ 12 mo after (neo)adjuvant chemotherapy and then only received 1 line of therapy in the metastatic setting assessed the benefit of SG in this subgroup vs the overall trial population. Methods: In ASCENT, pts with mTNBC refractory/relapsing after ≥ 2 prior chemotherapies were randomized 1:1 to receive SG (10 mg/kg IV on days 1 and 8, every 21 days) or TPC (capecitabine, eribulin, vinorelbine, or gemcitabine). Per protocol, a pt was eligible after only 1 prior regimen in the metastatic setting if their disease recurred within 12 months of completing (neo)adjuvant therapy. Primary endpoint was PFS per RECIST 1.1 by independent review in brain metastases-negative (BMNeg) pts. Efficacy and safety was assessed in a subset of pts who recurred ≤ 12 mo after (neo)adjuvant chemotherapy and then received 1 line of therapy in the metastatic setting. Results: In total, 33 and 32 BMNeg pts with a median age of 49 and 51 yrs received SG and TPC in this subgroup, respectively. In this subgroup, treatment with SG (vs TPC) improved PFS (median 5.7 vs 1.5 mo; HR, 0.41; 95% CI, 0.22-0.76; P = 0.0049) and OS (median 10.9 vs 4.9 mo; HR, 0.51; 95% CI, 0.28-0.91; P = 0.0227). We also observed higher ORR (30% vs 3%) and CBR (42% vs 6%) with a median response duration of 6.7 mo with SG vs not calculable with TPC. The efficacy results from this subgroup are similar to those for SG vs TPC in the overall BMNeg population. The safety profile of SG in pts in this subgroup was consistent with prior reports. There were no treatment-related deaths with SG. Conclusions: Pts with mTNBC who recurred ≤ 12 mo after (neo)adjuvant therapy and then had 1 line of prior therapy in the metastatic setting may represent a subset with more aggressive disease. In this subgroup, pts had superior outcomes with SG vs TPC in the second-line metastatic setting, consistent with the benefit seen in the overall BMNeg population. Studies are ongoing (NeoSTAR, NCT04230109; SASCIA, NCT04595565) to evaluate SG as an earlier-line treatment option for TNBC. Clinical trial information: NCT02574455 .

The prognostic performance of PREDICT+ in patients (pts) with HER2-positive (HER2+) early-stage breast cancer (EBC)

524

Background: PREDICT+ is a widely used, free, online tool based on traditional clinico-pathological features, including HER2, developed to predict individual mortality of EBC pts and to aid clinical decision making for adjuvant therapy. However, its prognostic role in HER2+ EBC pts treated with chemotherapy (CT) and anti-HER2 therapies remains unclear. We aimed to investigate the prognostic performance of PREDICT+ in HER2+ EBC pts enrolled in the ALTTO trial. Methods: ALTTO is a phase III study evaluating adjuvant lapatinib (L) +/- trastuzumab (T) vs. T alone in pts with HER2+ EBC. Pts enrolled in the ALTTO trial and receiving T-based therapy started concurrently with CT were eligible for this analysis. We calculated PREDICT+ estimates using variables extracted from ALTTO database, blinded to pts outcomes. The prognostic performance of PREDICT+ was evaluated by assessing its calibration and discriminatory accuracy. For calibration, median predicted 5-year (5-yr) overall survival (OS) was compared to observed 5-yr OS. For discriminatory accuracy, the area under the receiver-operator characteristic (AUC under the ROC) curve and corresponding 95% confidence intervals (CI) for predicted 5-yr OS were calculated. Subgroup analyses were performed according to type of anti-HER2 therapy, type of CT, age, hormone receptor (HR) status, nodal status and tumor size. Results: This analysis included 2,794 pts. After a median follow-up of 6.0 years (IQR, 5.8-6.7), 182 deaths were observed. Overall, PREDICT+ underestimated 5-yr OS by 6.7% (95% CI, 5.8-7.6): observed 5-year OS was 94.7% vs. predicted 88.0%. The underestimation was consistent across all subgroups (Table). For discriminatory accuracy, AUC under the ROC curve was 73.7% (95%CI 69.7-77.8) in the overall population, ranging between 61.7% and 77.7% across the analysed subgroups. Conclusions: In HER2+ EBC pts enrolled in the ALTTO trial, the PREDICT+ score highly underestimated OS. The low performance of this prognostic tool was consistent across all pts subgroups. PREDICT+ should be used with caution to give prognostic estimation in HER2+ EBC pts treated in the modern era with effective chemotherapy and anti-HER2 targeted therapies.[Table: see text]

ALEXANDRA/IMpassion030: A phase 3 study of standard adjuvant chemotherapy with or without atezolizumab in patients with early-stage triple-negative breast cancer

TPS597

Background: Early stage triple negative breast cancer (TNBC) is associated with a high risk of distant relapse. Because TNBC does not currently have specific targeted agents approved for use in the early setting, it is treated primarily with chemotherapy. TNBC may be more immunogenic than other subtypes of breast cancer. Atezolizumab (an anti–PD-L1 antibody), in combination with nab-paclitaxel has been approved in >70 countries for the treatment of PD-L1-positive unresectable locally advanced or metastatic TNBC based on the results of the randomized phase 3 IMpassion130 trial. The phase 3 IMpassion031 study, evaluating atezolizumab in combination with chemotherapy (nab-paclitaxel followed by doxorubicin and cyclophosphamide) in comparison to placebo plus chemotherapy as neoadjuvant treatment demonstrated a statistically significant and clinically meaningful improvement in pCR in both PD-L1 positive and PD-L1 negative tumors. ALEXANDRA/IMpassion030 is a global, prospective, randomized, open-label, phase 3 trial currently investigating the efficacy, safety and pharmacokinetic profile of adjuvant atezolizumab plus standard anthracycline/taxane adjuvant chemotherapy versus chemotherapy alone in early stage TNBC. Methods: ALEXANDRA/IMpassion030 will randomize 2300 patients with operable stage II-III TNBC, confirmed by central pathology review. Patients are stratified by type of surgery, nodal status, and centrally assessed PD-L1 status. Adjuvant chemotherapy consist of weekly paclitaxel 80 mg/m2 for 12 weeks followed by dose dense anthracycline (epirubicin 90 mg/m2 or doxorubicin 60 mg/m2) and cyclophosphamide 600 mg/m2 for 4 doses every 2 weeks or the same chemotherapy regimen (T-EC/AC) given concomitantly with atezolizumab 840 mg every 2 weeks followed by maintenance atezolizumab 1200 mg every 3 weeks until completion of 1 year of atezolizumab. The primary endpoint is invasive disease-free survival (iDFS) and secondary endpoints include, iDFS in the PD-L1 selected tumour status (IC1/2/3) and node-positive subpopulations, overall survival, safety, patient functioning and health related quality of life (HRQoL). Tumor tissue and blood samples will be collected for biomarker research. The first site was activated on May 4 2018, and approximately 373 sites in 30 countries are currently participating in this trial. This trial is sponsored by F. Hoffmann-La Roche Ltd and conducted in partnership with the Breast International Group, Frontier Science and Technology Research Foundation, Institute Jules Bordet and Alliance Foundation Trials. Clinical trial information: NCT03498716.

Overcoming Barriers to Clinical Trials Cooperation: The Breast International Group Example

Clinical trials cooperation is not a luxury; it is a necessity, now more than ever, first in light of the segmentation of tumors according to their molecular targets-which are being matched to an increasing number of competitive drugs-and second because it is the only chance to maintain academic research centered on addressing patients' needs. In its 21 years of existence, the Breast International Group, an umbrella organization supporting the activities of 54 member groups across six continents, has been confronted with challenges that include (1) keeping trust and motivation within the network; (2) improving the interface between academia and industry; (3) improving patient involvement and trust in clinical trials; and (4) fundraising for noncommercial research. We describe how these challenges have been addressed so far, with the hope of empowering the next generation of clinical investigators.

MINDACT: Long-term results of the large prospective trial testing the 70-gene signature MammaPrint as guidance for adjuvant chemotherapy in breast cancer patients

506

Background: The 70-gene signature MammaPrint has been shown to identify breast cancer patients for whom adjuvant chemotherapy (CT) could be safely omitted even in the presence of unfavorable standard clinical-pathological criteria. The MINDACT primary endpoint at 5 years median follow-up was met in 2016 (Cardoso et al, NEJM 2016) with a distant metastasis free survival (DMFS) rate at 5 years of 94.7% (95% CI: 92.5-96.2) in clinical high (C-High) / genomic low (G-Low) risk patients who received no CT. Longer follow-up is now available. Methods: 6693 patients were enrolled in the prospective phase III randomized MINDACT study (EORTC 10041/BIG3-04) between 2007-2011. We assessed the DMFS rate at 5 years in the primary test (PT) population of C-High / G-Low patients who were randomized to receive no CT (n = 644). As secondary analysis, we evaluated DMFS and overall survival (OS) in the intention to treat (ITT) population of the C-High / G-Low group randomized to CT vs no CT (n = 749 and 748 respectively). Comparisons between CT and no CT groups are low-powered. We used Kaplan-Meier estimates for time to event endpoints and hazard ratios (HR) with 95% CI from cox-regression models adjusted for stratification factors used for the randomization. Results: The median follow-up is 8.7 years, resulting in an updated 5-year DMFS rate for the PT population of C-High / G-Low patients with no CT of 95.1% (95% CI 93.1-96.6). The updated outcomes of the ITT population of C-High / G-Low patients are shown in the table. Further analyses will update the suggested age-dependent effect of CT omission for luminal breast cancer seen at 5 years in pre- versus post-menopausal women as in Tailor-X (Piccart et al, SABCS 2019). Conclusions: The primary DMFS endpoint at 5 years continues to be met in CT untreated C-High / G-Low risk women, confirming MINDACT as a positive de-escalation study. With longer follow-up and in line with the natural history of luminal breast cancer, more distant relapses do occur but the estimated gain of 2.6% for CT administration in C-High / G-Low patients remains small in light of CT harmful effects. The level IA evidence for the clinical utility of the 70-gene signature for adjuvant CT decision making is maintained. Clinical trial information: NCT00433589 . [Table: see text]

Mechanisms of resistance to trastuzumab emtansine (T-DM1) in HER2-positive breast cancer

The HER2-targeted antibody-drug conjugate trastuzumab emtansine (T-DM1) is approved for the treatment of metastatic, HER2-positive breast cancer after prior trastuzumab and taxane therapy, and has also demonstrated efficacy in the adjuvant setting in incomplete responders to neoadjuvant therapy. Despite its objective activity, intrinsic and acquired resistance to T-DM1 remains a major clinical challenge. T-DM1 mediates its activity in a number of ways, encompassing HER2 signalling blockade, Fc-mediated immune response and payload-mediated microtubule poisoning. Resistance mechanisms relating to each of these features have been demonstrated, and we outline the findings of these studies in this review. In our overview of the substantial literature on T-DM1 activity and resistance, we conclude that the T-DM1 resistance mechanisms most strongly supported by the experimental data relate to dysfunctional intracellular metabolism of the construct and subversion of DM1-mediated cell killing. Loss of dependence on signalling initiated by HER2-HER2 homodimers is not substantiated as a resistance mechanism by clinical or experimental studies, and the impact of EGFR expression and tumour immunological status requires further investigation. These findings are instructive with respect to strategies that might overcome T-DM1 resistance, including the use of second-generation anti-HER2 antibody-drug conjugates that deploy alternative linker-payload chemistries.

B-PRECISE-01 Study: A phase Ib trial of MEN1611, a PI3K Inhibitor, combined with trastuzumab ± fulvestrant for the treatment of HER2-positive advanced or metastatic breast cancer

TPS1101

Background: MEN1611 is a potent, selective class I inhibitor of PI3K, a key enzyme in the transduction of various extracellular growth factor signals essential for cell survival and apoptosis. The discovery in human cancers of frequent PIK3CA mutations, that have been linked to a worse outcome in advanced HER2-positive breast cancer, makes PI3K an attractive therapeutic target. Preclinical and clinical evidences support the development of MEN1611 in combination with other agents in the context of solid tumors. Methods: B-PRECISE-01 is an open-label, multicenter, phase Ib dose escalation study in patients with PIK3CA mutant tumors, HER2-positive advanced or metastatic breast cancer which has progressed after at least 2 lines of anti-HER2 based therapy. PIK3CA mutations are assessed centrally by real-time PCR assay in DNA derived from archived tumor samples. MEN1611 will be administered orally BID for continuous 28-day cycles until disease progression, in combination with weekly IV infusions of trastuzumab. In addition, HR-positive postmenopausal patients will also be treated with fulvestrant. After the completion of the dose escalation phase (Step 1), the study will continue in an expansion cohort (Step 2) testing the Recommended Phase 2 dose (RP2D) in a total of 15 patients in each of the treatment groups. The primary study objective is to assess combination safety and select RP2D. Secondary objectives include assessment of pharmacokinetics and pharmacodynamics, preliminary clinical activity of MEN1611 in combination with trastuzumab +/- fulvestrant, and correlation with PIK3CA mutations and other relevant cancer genes mutational status. Adverse events will be graded according to NCI CTCAE v4.03. Responses will be evaluated according to RECIST v1.1. Study variables will be presented by dose-cohort and overall using appropriate descriptive statistics. The enrollment began in July 2018 at European sites and US sites will shortly participate; up to date the first dose cohort level has been achieved. Clinical trial information: NCT03767335.

On-treatment changes in tumor-infiltrating lymphocytes (TIL) during neoadjuvant HER2 therapy (NAT) and clinical outcome

574

Background: Higher quantity of pretreatment TIL (PT) is associated with improved pCR and EFS in HER2+ early breast cancer (BC). The value of on-treatment TIL is unknown. Methods: The NeoALTTO trial randomized 455 women with HER2+ BC to 12 weeks NAT with trastuzumab, lapatinib or combination with paclitaxel, followed by FEC after surgery. In the PAMELA trial 151 women received 18 weeks NAT with lapatinib and trastuzumab (±hormonal therapy). TIL were quantified on PT and on-treatment (W2) biopsies using the published method on H&E slides, and tested for associations with pCR (logistic regression), EFS and OS (Cox models) in univariate (UV) and multivariate (MV) analyses. The likelihood ratio test assessed added prognostic value to clinicopathological (CP) variables. pCR associations were validated in PAMELA. We investigated enrichment of immune cell subsets using previously published RNAseq data from NeoALTTO. Results: In NeoALTTO, PT and W2 TIL were evaluable in 277/455 (61%). We defined two groups: immune-poor (L+F) and immune-enriched (II+P), see Table. Immune-enriched (41%; 134) vs poor (59%; 164) patients had significantly higher pCR rates (40% vs 21%; UV OR 2.24; 95%CI 1.31-3.85; P = .003; MV P = .009), and added significant value to CP + PT TIL for prediction of pCR (P = .003). This was further confirmed in PAMELA (N = 94/151) (26% vs 6%; UV P = .021; MV P = .028). In NeoALTTO, the immune-enriched vs poor patients had significantly improved EFS (5 yr est 85% vs 60%; UV HR 0.31; 95%CI 0.18-0.54; P < .001; MV P < .001) and OS (5 yr est 91% vs 77%; UV HR 0.40; 95%CI 0.20-0.82; P = .012; MV P = 0.026), and provided significant added prognostic value beyond CP + pCR + PT TIL (EFS P < .001) In NeoALTTO PT samples, II vs F patients had enrichment of DCs, NKs and CD8+ including tissue resident memory cells (P = .009) suggesting requirement of key immune subsets. Further validation by IHC is ongoing. Conclusions: On-treatment TIL identifies patients more likely to achieve pCR and have improved EFS in early-stage HER2+ BC, beyond CP + PT TIL. This information could aid future trial design. Clinical trial information: NCT00553358, NCT01973660. [Table: see text]

Autoimmunity and Benefit from Trastuzumab Treatment in Breast Cancer: Results from the HERA Trial

BACKGROUND/AIM

This study sought to determine whether an autoimmune background could identify patients with HER2-positive early breast cancer (EBC) who derive differential benefit from primary adjuvant trastuzumab-based therapy.

PATIENTS AND METHODS

HERA is an international randomized trial of 5,102 women with HER2-positive EBC, who were enrolled to either receive adjuvant trastuzumab or not. In this exploratory analysis, the interaction between autoimmune history and the magnitude of trastuzumab benefit was evaluated.

RESULTS

A total of 5,099 patients were included in the current analysis. Among them, 325 patients (6.4%) had autoimmune disease history, 295 of whom had active disease. Patients were randomly assigned to trastuzumab or no-trastuzumab groups. Similar reductions in the risk of events in patients with and without autoimmune history were observed (interaction p=0.95 for disease-free survival, and p=0.62 for overall survival).

CONCLUSION

No evidence of a differential benefit from trastuzumab in patients with a medical history of autoimmune disease was found.

Association of p27 and Cyclin D1 Expression and Benefit from Adjuvant Trastuzumab Treatment in HER2-Positive Early Breast Cancer: A TransHERA Study

Purpose: To assess the prognostic and predictive value of selected biomarkers involved in cell-cycle regulation or proliferation in patients with HER2-positive early breast cancer.Experimental Design: Protein expression of TOP2A, Ki67, cyclin D1, and p27 was immunohistochemically determined in tissue microarrays of surgical specimens from 862 patients randomized to trastuzumab (1 or 2 years; N = 561) and observation (N = 301) arms of the HERA trial. The primary analysis endpoint was disease-free survival (DFS). Biomarkers were examined as continuous or categorical variables (predefined cutoffs). Interaction terms between biomarkers and treatment were assessed in multivariate Cox models adjusted for variables of clinical interest.Results: A significant interaction was detected between p27 and treatment (adjusted P = 0.0049). Trastuzumab effect was significant in the p27-low subgroup (≤70% p27-positive tumor cells; N = 318). HR _{Comb Trast vs. Obs} 0.44, 95% CI, 0.29-0.65 (P < 0.001). No trastuzumab effect was observed in the p27-high subgroup N = 435; HR _{Comb Trast vs. Obs} 0.97, 95% CI, 0.66-1.44, P = 0.89), indicating that these patients derived little or no benefit from trastuzumab treatment. A prognostic effect of p27 on DFS was observed, with p27-high patients experiencing half the hazard of a DFS event compared with low ones (HR _{p27 High vs. Low} 0.49, 95% CI, 0.32-0.75). TOP2A, Ki67, and cyclin D1, as categorical variables were not predictive, whereas cyclin D1 as continuous variable was predictive of trastuzumab benefit.Conclusions: In TransHERA, patients with HER2-positive early breast cancer with low p27 expression in their tumors benefited from trastuzumab treatment, whereas patients with high p27 expression did not. Clin Cancer Res; 24(13); 3079-86. ©2018 AACR.

Somatic mutation, copy number and transcriptomic profiles of primary and matched metastatic estrogen receptor-positive breast cancers

BACKGROUND

Estrogen receptor-positive (ER+) breast cancers (BCs) constitute the most frequent BC subtype. The molecular landscape of ER+ relapsed disease is not well characterized. In this study, we aimed to describe the genomic evolution between primary (P) and matched metastatic (M) ER+ BCs after failure of adjuvant therapy.

MATERIALS AND METHODS

A total of 182 ER+ metastatic BC patients with long-term follow-up were identified from a single institution. P tumor tissue was available for all patients, with 88 having matched M material. According to the availability of tumor material, samples were characterized using a 120 mutational hotspot qPCR, a 29 gene copy number aberrations (CNA) and a 400 gene expression panels. ESR1 mutations were assayed by droplet digital PCR. Molecular alterations were correlated with overall survival (OS) using the Cox proportional hazards regression models.

RESULTS

The median follow-up was 6.4 years (range 0.5-26.6 years). Genomic analysis of P tumors revealed somatic mutations in PIK3CA, KRAS, AKT1, FGFR3, HRAS and BRAF at frequencies of 41%, 6%, 5%, 2%, 1% and 2%, respectively, and CN amplification of CCND1, ZNF703, FGFR1, RSF1 and PAK1 at 23%, 19%, 17%, 12% and 11%, respectively. Mutations and CN amplifications were largely concordant between P and matched M (>84%). ESR1 mutations were found in 10.8% of the M but none of the P. Thirteen genes, among which ESR1, FOXA1, and HIF1A, showed significant differential expression between P and M. In P, the differential expression of 18 genes, among which IDO1, was significantly associated with OS (FDR < 0.1).

CONCLUSIONS

Despite the large concordance between P and matched M for the evaluated molecular alterations, potential actionable targets such as ESR1 mutations were found only in M. This supports the importance of characterizing the M disease. Other targets we identified, such as HIF1A and IDO1, warrant further investigation in this patient population.

APHINITY trial (BIG 4-11): A randomized comparison of chemotherapy (C) plus trastuzumab (T) plus placebo (Pla) versus chemotherapy plus trastuzumab (T) plus pertuzumab (P) as adjuvant therapy in patients (pts) with HER2-positive early breast cancer (EBC)

LBA500

Background: In previous trials P significantly prolonged progression free and overall survival and increased pCR rates when added to T+C in pts with HER2-positive breast cancer (BC). The APHINITY trial was designed to test whether the addition of P to adjuvant T+C improves pt outcomes. Methods: Pts with adequately excised HER2-positive, pT1-3 EBC were randomly assigned to receive standard adjuvant C plus one year of either T + P or T + Pla. Eligible pts had either node-positive disease, or node-negative disease (pN0) and a tumor size of > 1.0 cm. Pts with pN0, T1b tumors with high risk features were initially eligible. The primary efficacy endpoint was invasive disease-free survival (IDFS); we assumed a 3-year IDFS of 91.8% with P and 89,.2% with Pla. Results: 4805 pts were randomized to C and T plus either P (n = 2400) or Pla (n = 2405). Baseline demographics and tumor characteristics between the arms were well balanced, with 63% and 36% of pts having node-positive and hormone receptor negative EBC respectively. P and Pla treatments were completed in 84.5% and 87.4% of patients, respectively. IDFS events occurred in 171 (7.1%) P pts and 210 (8.7%) Pla pts (hazard ratio (HR) 0.81 (95% CI 0.68-1.00), P = 0.045). Estimates of IDFS at 3 years were 94.1% and 93.2% in the P and Pla arms, respectively. The node-positive cohort had a 3-year IDFS rate of 92.0% for P compared with 90.2% for Pla (HR 0.77 (95% CI 0.62-0.96), P = 0.019). The pN0 cohort had a 3-year IDFS rate of 97.5% for P and 98.4% for Pla; HR = 1.13 (95% CI 0.68-1.86). The safety profile of P was consistent with previous trials. For the primary cardiac endpoint (heart failure or cardiac death) and secondary cardiac endpoint (asymptomatic or mildly symptomatic LVEF decline) rates were low, 0.7% vs 0.3% and 2.7% vs 2.8%, in the P and Pla arms, respectively. Diarrhea grade ≥3 was more frequent with P (9.9% vs 3.7%). Conclusions: The APHINITY trial met its primary endpoint: P significantly improved IDFS in patients with HER2-positive EBC when added to T+C. No new safety signals were identified. Clinical trial information: NCT01358877.

Standard anthracycline-based vs. docetaxel-capecitabine in early breast cancer: Results from the chemotherapy randomization (R-C) of EORTC 10041/ BIG 3-04 MINDACT phase III trial

516

Background: The MINDACT trial demonstrated that 46% of breast cancer patients (pts) at high clinical (C) but low genomic (G) risk based on MammaPrint (70-gene signature), might safely forego adjuvant CT (Cardoso NEJM 2016). A second 1:1 randomization (R-C) was optional in all pts for whom CT was decided, between standard anthracycline-based regimens (AT) and experimental docetaxel 75 mg/m² IV + oral capecitabine 825 mg/m² bid x 14 days (DC), q3wks for 6 cycles after surgery. Methods: MINDACT included 6693 pts, of whom 2895 received CT. C-low/G-low pts were allocated to no CT, C-high/G-high to CT and those with discordant G/C results were randomized to use either G or C risk to decide use of CT. Primary endpoint for R-C was disease-free survival (DFS). Secondary endpoints included OS and safety. Statistical hypothesis: HR-0.76 in favour of DC. Results: A total of 1301 pts (45%), of whom 787 (61%) were C-high/G-high, 351 (27%) C-high/G-low, 137 (11%) C-low/G-high, and 26 (2%) C-low/G-low, were randomized to AT or DC. Main reason for not inclusion in R-C was CT given outside the trial. Compliance rates for R-C were 97% overall. At 5-years median follow-up, DFS was not significantly different between AT (649 pts) and DC (652 pts) [HR = 0.83 (0.60- 1.15, p = 0.263], and OS was similar in both arms (HR 0.91, 95% CI, 0.54- 1.53). For the relevant C-high/G-high group, DFS was also not different (5-years DFS 86.1 vs 88.1%; HR 0.83, 95% CI, 0.58-1.21). Of note, number of events is still small (AT: 30; DC: 27). Commonest adverse events in DC were grade 2 hand/foot syndrome (28.5% vs 3.3%), grade 2 diarrhea (13.7% vs 5.8%) and grade 1 peripheral neuropathy (27.1% vs 11.2%). Grade 2 anemia (14.2% vs 5.1%) and grade 4 neutropenia (24.6% vs 20.5%) were higher in AT. Cardiac events occurred in 9 pts overall, including 1 cardiac failure (AT), while 53 pts developed secondary cancers (AT: 32; DC: 21; leukemia: 2 in AT vs. 1 in DC). Four deaths occurred (AT:1 and DC:3) while on therapy. Conclusions: Docetaxel-capecitabine did not improve DFS or OS, compared with standard anthracycline-based CT, including for the C-high/G-high group. Safety profile of both regimens was as expected. Clinical trial information: NCT00433589.

Survival outcomes of the NeoALTTO study: Updated results of a randomized multicenter phase III neoadjuvant trial

512

Background: In the neoadjuvant NeoALTTO trial dual HER2 blockade with lapatinib (L) plus trastuzumab (T) combined with weekly paclitaxel significantly increased the pathologic complete response rate (pCR) compared with either anti-HER2 agent alone plus paclitaxel. At first analysis pts with pCR had a better event free survival (EFS) and overall survival (OS) after median follow-up of 3.84 yrs. Methods: 455 pts with operable HER2-positive breast cancer were randomized to receive either L (n=154) 1500mg/day, T 4mg/kg loading dose followed by 2mg/kg/wk (n=149) or L 1000mg/day plus T (n=152) for 6 weeks followed by the assigned anti-HER2 treatment combined with paclitaxel weekly x 12. Following surgery pts received 3 cycles fluorouracil, epirubicin and cyclophosphamide q 3 weeks. The assigned anti-HER2 treatment was continued for 34 weeks thereafter. Primary endpoint was pCR (ypT0/is), secondary endpoints were EFS and OS and the association between pCR and OS analyzed by landmark analysis 30 weeks after randomization. Median follow-up was 6.7 years. Results: 6-yrs EFS rate was 67%/ 67%/74% with L/T/TL, respectively (L vs T HR 0.98 [95% CI 0.64–1.51] p=0.93; TL vs T HR 0.81 [95% CI 0.52–1.26] p=0.35). In the hormone receptor negative group 6- yrs EFS rate was 61%/ 63%/74% for the 3 groups, respectively (L vs T HR 1.09 [95% CI 0.61–1.95] p=0.76; TL vs T HR 0.81 [95% CI 0.44–1.51] p=0.52). OS at 6 yrs was 82%/79%/85% for L, T and TL, respectively (L vs T: HR 0.85 [95% CI 0.49-1.46] p=0.56; TL vs T HR 0.72 [95% CI 0.41-1.27] p=0.26). In landmark analyses, pts with a pCR had significantly higher 6-yrs EFS (77% /65%) and OS (89% /77%) compared to those without pCR, both overall and for the hormone receptor negative cohort. Conclusions: The updated results of the NeoALTTO study confirm the sustained survival benefits for pts who achieve a pCR. EFS and OS after 6 yrs did not differ significantly between the 3 treatment groups. The combination of T and L showed numerically higher EFS compared to T, especially in the hormone-receptor negative group. Clinical trial information: NCT00553358. [Table: see text]

Updated results from the phase III ALTTO trial (BIG 2-06; NCCTG (Alliance) N063D) comparing one year of anti-HER2 therapy with lapatinib alone (L), trastuzumab alone (T), their sequence (T→L) or their combination (L+T) in the adjuvant treatment of HER2-positive early breast cancer

502

Background: Pre-specified 5-year analyses of the phase III Adjuvant Lapatinib and/or Trastuzumab Treatment Optimisation (ALTTO) Trial defined in Amendments 11&12. Methods: From June 2007 to July 2011, 8381 patients (pts) were randomised from 946 sites in 44 countries to receive either L+T, T→L, L, or T. In 2011, due to futility the L arm was closed and is not included in this analysis. The primary end point is disease-free survival (DFS). Secondary objectives include treatment comparisons with respect to overall survival (OS), time to recurrence (TTR), time to distant recurrence (TDR), cardiac and overall safety and tolerability. Primary analysis results of the study were published in JCO 2015 34:1034-1042. This updated analysis occurs at a 6.9 yrs median follow up (MFU). Results: All patients have reached 5-years of follow-up. 705 DFS events for L+T vs T have been observed. HR for DFS was 0.86 (95% CI, 0.74-1.00; 6-yr DFS%=85% vs 82%) for L+T vs T and 0.93 (95% CI, 0.81-1.08; 6-yr DFS%=84% vs 82%) for T→L vs. T. The 6-year OS was 93%, 92%, and 91% for L+T, T→L, and T, respectively. HR for OS was 0.86 (95% CI, 0.70-1.06) for L+T vs. T and 0.88 (95% CI, 0.71-1.08) for T→L vs. T. DFS differences for L+T vs. T were slightly higher for the hormone-receptor(ER)-negative [HR 0.80 (95% CI, 0.64-1.00; 6-yr DFS%=84% vs. 80%)] and the sequential chemotherapy [HR 0.83 (95% CI, 0.69-1.00; 6-yr DFS%=83% vs.79%)] subgroups. There were no differences in sites of first DFS events according to treatment arm for CNS, loco-regional, or distant recurrences. There were more AEs related to study treatment (L+T 93% vs T 64%). The incidence of primary cardiac end points was low: 1% for L+T, 0.5% for T→L and 0.9% for T. Conclusions: The HRs for this updated analysis are similar to those from the Primary Analysis and the event rate remains lower than anticipated (705 vs 850 planned). Cardiac toxicity remains low. This analysis suggests that HER2+/ER- tumors may have a different biology than HER2+/ER+ and may benefit more from dual HER2 blockade. Long-term follow up continues. Clinical trial information: NCT00490139.

APHINITY trial (BIG 4-11): A randomized comparison of chemotherapy (C) plus trastuzumab (T) plus placebo (Pla) versus chemotherapy plus trastuzumab (T) plus pertuzumab (P) as adjuvant therapy in patients (pts) with HER2-positive early breast cancer (EBC)

LBA500

The full, final text of this abstract will be available at abstracts.asco.org at 7:30 AM (EDT) on Monday, June 5, 2017, and in the Annual Meeting Proceedings online supplement to the June 20, 2017, issue of the Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Monday edition of ASCO Daily News.

11 years' follow-up of trastuzumab after adjuvant chemotherapy in HER2-positive early breast cancer: final analysis of the HERceptin Adjuvant (HERA) trial

BACKGROUND

Clinical trials have shown that trastuzumab, a recombinant monoclonal antibody against HER2 receptor, significantly improves overall survival and disease-free survival in women with HER2-positive early breast cancer, but long-term follow-up data are needed. We report the results of comparing observation with two durations of trastuzumab treatment at a median follow-up of 11 years, for patients enrolled in the HERA (HERceptin Adjuvant) trial.

METHODS

HERA (BIG 1-01) is an international, multicentre, open-label, phase 3 randomised trial of 5102 women with HER2-positive early breast cancer, who were enrolled from hospitals in 39 countries between Dec 7, 2001, and June 20, 2005. After completion of all primary therapy (including, surgery, chemotherapy, and radiotherapy as indicated), patients were randomly assigned (1:1:1) to receive trastuzumab for 1 year (once at 8 mg/kg of bodyweight intravenously, then 6 mg/kg once every 3 weeks) or for 2 years (with the same dose schedule), or to the observation group. Primary endpoint is disease-free survival, and analyses are in the intention-to-treat population. Hazard ratios (HRs) were estimated from Cox models, and survival curves were estimated by the Kaplan-Meier method. Comparison of 2 years versus 1 year of trastuzumab is based on 366-day landmark analyses. This study is registered with ClinicalTrials.gov (NCT00045032).

FINDINGS

Of the 5102 women randomly assigned in the HERA trial, three patients had no evidence of having provided written informed consent to participate. We followed up the intention-to-treat population of 5099 patients (1697 in observation, 1702 in 1-year trastuzumab, and 1700 in 2-years trastuzumab groups). After a median follow-up of 11 years (IQR 10·09-11·53), random assignment to 1 year of trastuzumab significantly reduced the risk of a disease-free survival event (HR 0·76, 95% CI 0·68-0·86) and death (0·74, 0·64-0·86) compared with observation. 2 years of adjuvant trastuzumab did not improve disease free-survival outcomes compared with 1 year of this drug (HR 1·02, 95% CI 0·89-1·17). Estimates of 10-year disease-free survival were 63% for observation, 69% for 1 year of trastuzumab, and 69% for 2 years of trastuzumab. 884 (52%) patients assigned to the observation group selectively crossed over to receive trastuzumab. Cardiac toxicity remained low in all groups and occurred mostly during the treatment phase. The incidence of secondary cardiac endpoints was 122 (7·3%) in the 2-years trastuzumab group, 74 (4·4%) in the 1-year trastuzumab group, and 15 (0·9%) in the observation group.

INTERPRETATION

1 year of adjuvant trastuzumab after chemotherapy for patients with HER2-positive early breast cancer significantly improves long-term disease-free survival, compared with observation. 2 years of trastuzumab had no additional benefit.

FUNDING

F Hoffmann-La Roche (Roche).

Abstract PD7-01: Can surrogate pathological subtyping replace molecular subtyping? Outcome results from the MINDACT trial

Background

Molecular subgroups within early breast cancer (EBC), such as Luminal A, Luminal B, HER-2+, Basal-like may help to best to identify patients for specific treatment regimens. Controversy exists as to which methodology is best at identifying these molecular subgroups. Immunohistochemistry (IHC) may be used as a surrogate method to stratify patients. Molecular subtyping gene expression based tests, such as BluePrint, measure a greater number of genes than pathological criteria. ER, PgR, HER-2 and Ki67 are measured individually at the protein level, while BluePrint is designed to capture the functional underlying biologic pathway regulated by these receptors.

Methods

The MINDACT trial is an international, prospective, randomized, phase III trial which has proventhe clinical utility of MammaPrint in selecting EBC patients who can safely avoid chemotherapy. Here we present the results of a preplanned MINDACT sub-study to compare outcome based on molecular subtyping (MS) to surrogate pathological subtyping (PS) as endorsed by 2013 St. Gallen Consensus. MS data were obtained by MammaPrint (MP) and BluePrint classifying patients in the following subtypes: Luminal A (MP Low Risk); Luminal B (MP High Risk); HER2-type; and Basal-type. ER, PgR, HER2 and Ki67 protein status were centrally assessed by IHC/FISH. The primary hypothesis was that among PS Luminal patients, patients with HER-2+ or Basal-type tumors by MS would have a decreased DMFS compared to MS Luminal patients. At α=5% with 220 events, the study has 80% power to demonstrate this for HR=2.44.

Results

The table depicts classification of tumors according to PS versus MS for all patients (n=5,806).

PS versus MSMSPSLum ALum BHER-2+BasalTotalLum A24562708132747Lum B106979422861971HER-2 enriched1189531826557TN14107500531Total365711693556255806

Most pronounced differences: MS classified 54% as Luminal A among the Luminal B by PS. MS classified 38% as Luminal (A and B) and 5% as Basal-type among the HER-2+ by PS. MS classified 5% as Luminal (A and B) among the TN cases by PS.

MS identifies 63% of patients as Luminal A, while PS identifies 47%; 5yr DMFS for both methods was ≥ 96.0%.

PS Luminal cancers that were classified as HER-2+ or Basal-type by MS had a lower 5yr DMFS (88.0% for HER-2+ and 90.2% for Basal), albeit non-significant, than those who were also Luminal by MS (95.9%): HR= 1.40, 95% CI = 0.75-2.60.

In PS TN cancers, MS identified 24 out of 500 patients (5%) as Luminal-type with excellent prognosis (5yr DMFS of 100% versus 71.4% for MS HER-2+ or 90.1% for MS Basal-type).

Among the PS Luminal patients, Ki67 cut at 20% identified patients with ki67 low (69%), with 5yr DMFS ≥ 96.0% (better compared to the 14% cut-off).

Conclusions

1) MS was able to re-stratify 16% of patients to a low risk Luminal A-type group with an excellent outcome. 2) Among TN EBC, 5% were classified as Luminal by MS and had an excellent outcome. 3) Albeit limited by low numbers of patients in each subgroup, this study suggest that MS is better correlated with outcome. 4) The observed subtype discrepancies may have an impact on treatment decision making. 5) Centrally assessed Ki67 labeling index of 20% may be the best cut-off for surrogate differentiation between Luminal A and B.

Citation Format: Cardoso F, Slaets L, de Snoo F, Bogaerts J, van 't Veer LJ, Rutgers EJ, Piccart-Gebhart MJ, Stork-Sloots L, Russo L, Dell'Orto P, Viale G. Can surrogate pathological subtyping replace molecular subtyping? Outcome results from the MINDACT trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD7-01.

Role of Troponins I and T and N-Terminal Prohormone of Brain Natriuretic Peptide in Monitoring Cardiac Safety of Patients With Early-Stage Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer Receiving Trastuzumab: A Herceptin Adjuvant Study Cardiac Marker Substudy

Purpose Women receiving trastuzumab with chemotherapy are at risk for trastuzumab-related cardiac dysfunction (TRCD). We explored the prognostic value of cardiac markers (troponins I and T, N-terminal prohormone of brain natriuretic peptide [NT-proBNP]) to predict baseline susceptibility to develop TRCD. We examined whether development of cardiac end points or significant left ventricular ejection fraction (LVEF) drop was associated with markers' increases. Patients and Methods Cardiac marker assessments were coupled with LVEF measurements at different time points for 533 patients from the Herceptin Adjuvant (HERA) study who agreed to participate in this study. Patients with missing marker assessments were excluded, resulting in 452 evaluable patients. A primary cardiac end point was defined as symptomatic congestive heart failure of New York Heart Association class III or IV, confirmed by a cardiologist, and a significant LVEF drop, or death of definite or probable cardiac causes. A secondary cardiac end point was defined as a confirmed significant asymptomatic or mildly symptomatic LVEF drop. Results Elevated baseline troponin I (> 40 ng/L) and T (> 14 ng/L), occurring in 56 of 412 (13.6%) and 101 of 407 (24.8%) patients, respectively, were associated with an increased significant LVEF drop risk (univariate analysis: hazard ratio, 4.52; P < .001 and hazard ratio, 3.57; P < .001, respectively). Few patients had their first elevated troponin value recorded during the study (six patients for troponin I and 25 patients for troponin T). Two patients developed a primary and 31 patients a secondary cardiac end point (recovery rate of 74%, 23 of 31). For NT-proBNP, higher increases from baseline were seen in patients with significant LVEF drop. Conclusion Elevated troponin I or T before trastuzumab is associated with increased risk for TRCD. A similar conclusion for NT-proBNP could not be drawn because of the lack of a well-established elevation threshold; however, higher increases from baseline were seen in patients with TRCD compared with patients without.

Relevance of Tumor-Infiltrating Immune Cell Composition and Functionality for Disease Outcome in Breast Cancer

Background

Not all breast cancer patients benefit from neoadjuvant or adjuvant therapy, resulting in considerable undertreatment or overtreatment. New insights into the role of tumor-infiltrating immune cells suggest that their composition, as well as their functionality, might serve as a biomarker to enable optimal patient selection for current systemic therapies and upcoming treatment options such as immunotherapy.

Methods

We performed several complementary unbiased in silico analyses on gene expression profiles of 7270 unrelated tumor samples of nonmetastatic breast cancer patients with known clinical follow-up. CIBERSORT was used to estimate the fraction of 22 immune cell types to study their relations with pathological complete response (pCR), disease-free survival (DFS), and overall survival (OS). In addition, we used four previously reported immune gene signatures and a CD8+ T-cell exhaustion signature to assess their relationships with breast cancer outcome. Multivariable binary logistic regression and multivariable Cox regression were used to assess the association of immune cell-type fractions and immune signatures with pCR and DFS/OS, respectively.

Results

Increased fraction of regulatory T-cells in human epidermal growth factor receptor 2 (HER2)-positive tumors was associated with a lower pCR rate (odds ratio [OR] = 0.15, 95% confidence interval [CI] = 0.03 to 0.69), as well as shorter DFS (hazard ratio [HR] = 3.13, 95% CI = 1.23 to 7.98) and OS (HR = 7.69, 95% CI = 3.43 to 17.23). A higher fraction of M0 macrophages in estrogen receptor (ER)-positive tumors was associated with worse DFS (HR = 1.66, 95% CI = 1.18 to 2.33) and, in ER-positive/HER2-negative tumors, with worse OS (HR = 1.71, 95% CI = 1.12 to 2.61). Increased fractions of γδ T-cells in all breast cancer patients related to a higher pCR rate (OR = 1.55, 95% CI = 1.01 to 2.38), prolonged DFS (HR = 0.68, 95% CI = 0.48 to 0.98), and, in HER2-positive tumors, with prolonged OS (HR = 0.27, 95% CI = 0.10 to 0.73). A higher fraction of activated mast cells was associated with worse DFS (HR = 5.85, 95% CI = 2.20 to 15.54) and OS (HR = 5.33, 95% CI = 2.04 to 13.91) in HER2-positive tumors. The composition of relevant immune cell types frequently differed per breast cancer subtype. Furthermore, a high CD8+ T-cell exhaustion signature score was associated with shortened DFS in patients with ER-positive tumors regardless of HER2 status (HR = 1.80, 95% CI = 1.07 to 3.04).

Conclusions

The main hypothesis generated in our unbiased in silico approach is that a multitude of immune cells are related to treatment response and outcome in breast cancer.

Tumor-Infiltrating Lymphocytes and Associations With Pathological Complete Response and Event-Free Survival in HER2-Positive Early-Stage Breast Cancer Treated With Lapatinib and Trastuzumab: A Secondary Analysis of the NeoALTTO Trial

IMPORTANCE

The presence of tumor-infiltrating lymphocytes (TILs) is associated with improved outcomes in human epidermal growth factor receptor 2 (HER2)-positive early breast cancer treated with adjuvant trastuzumab and chemotherapy. The prognostic associations in the neoadjuvant setting of other anti-HER2 agents and combinations are unknown.

OBJECTIVE

To determine associations between presence of TILs, pathological complete response (pCR), and event-free survival (EFS) end points in patients with early breast cancer treated with trastuzumab, lapatinib, or the combination.

DESIGN, SETTING, AND PARTICIPANTS

The NeoALTTO trial (Neoadjuvant Lapatinib and/or Trastuzumab Treatment Optimization) randomly assigned 455 women with HER2-positive early-stage breast cancer between January 5, 2008, and May 27, 2010, to 1 of 3 neoadjuvant treatment arms: trastuzumab, lapatinib, or the combination for 6 weeks followed by the addition of weekly paclitaxel for 12 weeks, followed by 3 cycles of fluorouracil, epirubicin, and cyclophosphamide after surgery. The primary end point used in this study was pCR in the breast and lymph nodes, with a secondary end point of EFS. We evaluated levels of percentage of TILs using hematoxylin-eosin-stained core biopsy sections taken at diagnosis (prior to treatment) in a prospectively defined retrospective analysis.

MAIN OUTCOMES AND MEASURES

Levels of TILs were examined for their associations with efficacy end points adjusted for prognostic clinicopathological factors including PIK3CA genotype.

RESULTS

Of the 455 patients, 387 (85.1%) tumor samples were used for the present analysis. The median (interquartile range [IQR]) level of TILs was 12.5% (5.0%-30.0%), with levels lower in hormone receptor-positive (10.0% [5.0%-22.5%]) vs hormone receptor-negative (12.5% [3.0%-35.0%]) samples (P = .02). For the pCR end point, levels of TILs greater than 5% were associated with higher pCR rates independent of treatment group (adjusted odds ratio, 2.60 [95% CI, 1.26-5.39]; P = .01). With a median (IQR) follow-up time of 3.77 (3.50-4.22) years, every 1% increase in TILs was associated with a 3% decrease in the rate of an event (adjusted hazard ratio, 0.97 [95% CI, 0.95-0.99]; P = .002) across all treatment groups.

CONCLUSIONS AND RELEVANCE

The presence of TILs at diagnosis is an independent, positive, prognostic marker in HER2-positive early breast cancer treated with neoadjuvant anti-HER2 agents and chemotherapy for both pCR and EFS end points.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00553358.

Abstract P6-01-04: Breast ultrasound and mammography and response to neoadjuvant lapatinib, trastuzumab and their combination in HER2 positive breast cancer: Results from Neo-ALTTO (BIG 1-06)

Mammography (Mx) and breast ultrasound (US) are the most commonly used diagnostic imaging modalities to estimate primary tumor size at the time of diagnosis. However, there are uncertainties regarding their use in the context of neoadjuvant therapy to predict pathologic complete response (pCR) or event-free survival (EFS). In this study, we sought to determine the value of Mx and US in predicting outcomes in women with HER2-positive breast cancer treated within the Neoadjuvant Lapatinib and/or Trastuzumab Treatment Optimisation (Neo-ALTTO) trial.

METHODS

Neo-ALTTO enrolled 455 women with invasive HER2-positive breast cancer and compared rates of pCR to neoadjuvant lapatinib, trastuzumab, and their combination. Each anti-HER2 therapy was given alone for 6 weeks, followed by 12 weeks of the same therapy plus weekly paclitaxel prior to surgery.

Mx and US were requested at baseline, week 6 and before surgery. Central imaging review was not pre-planned and two independent investigators (SDC and HAA Jr), blinded to assigned treatment and clinical outcomes, reviewed the measurements reported for each imaging modality and assigned the corresponding RECIST category of response. Responders were defined as patients who had either a partial or complete response (CR + PR). We evaluated the association between radiological response at week 6/surgery with both pCR and EFS.

RESULTS

A total of 340 (77%) and 267 (61%) pts had an evaluable US and Mx at weeks 6; and 309 (70%) and 248 (56%) pts had an evaluable US and Mx at the time of surgery. Early response (CR + PR) in the primary tumors was observed after 6 weeks of treatment in 32% pts by Mx and in 43% pts by US. pCR rates were twice as high for early responders than non-responders (week 6: 46% vs 23% by US, p =&lt;0.0001; 41% versus 24% by Mx, p= 0.007). The positive predictive value of US and Mx at surgery were 57% and 53%, respectively; the negative predictive values were 72% and 81%. The results according to hormone receptor status were similar to those in the overall patient population.There was no significant relationship between response at ultrasound and/or at mammography at 6 weeks/surgery and EFS.

CONCLUSION

Our results show that both Mx and US are underused during neo-adjuvant treatment, and further recommendations regarding the use of both imaging modalities should be explored prospectively. US may be used to assess early response to preoperative treatment in patients with HER2 positive breast cancer receiving anti-HER2 therapies, whereas Mx appears to be more useful in detecting residual disease at the time of surgery.

Citation Format: Di Cosimo S, Campbell C, Hazim Jr HA, Curigliano G, Criscitiello C, Crescenzo R, de la Pena L, Piccart-Gebhart MJ, Eidtmann H, Baselga J, de Azambuja E. Breast ultrasound and mammography and response to neoadjuvant lapatinib, trastuzumab and their combination in HER2 positive breast cancer: Results from Neo-ALTTO (BIG 1-06). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-01-04.

Abstract P4-01-01: Circulating tumor cell (CTC) enumeration and HER2 assessment as predictors of breast cancer outcomes in the ALTTO (BIG 2-06, Alliance N063D) Trial

Background: CTCs are associated with clinical outcomes in metastatic breast cancer irrespective of ER/PR/HER2 status. Some data support the prognostic relevance of serial CTC enumeration relative to adjuvant chemotherapy in early stage breast cancer. However, data from a large scale study focused on HER2 directed therapy for HER2+ disease have been lacking. We therefore sought to prospectively evaluate the effect of trastuzumab +/- lapatinib on CTCs and assess the prognostic/predictive value of CTC monitoring in HER2+ early stage breast cancer patients (pts).

Methods: The Adjuvant Lapatinib and/or Trastuzumab Treatment Optimisation (ALTTO; NCT00490139) Trial is an international, randomized, open-label phase III study of two targeted agents for HER2+ breast cancer. From June 2007 to July 2011, 8381 pts were randomised from 946 sites in 44 countries to 1 of 4 arms with sequential or concurrent chemotherapy: (i) 52 wks of trastuzumab (T); (ii) 52 wks of oral lapatinib (L); (iii) 12 or 18 wks of T followed by a washout and then 34 or 38 wks of L; or (iv) 52 wks of L+T. 540 (6%) pts provided optional informed consent and up to 30 mL peripheral blood suitable for CTC analyses at baseline with additional collections at 13 or 19 wks, 52 wks, 18 mos, 24 mos, and recurrence. CTC analyses are being conducted in three laboratories (Mayo Clinic Rochester, n=431; Institut Jules Bordet and University of Munich, n=109). 2-3 x 10 mL CellSave™ samples are pooled and processed at each time point for CTC enumeration and HER2 expression using the immunomagnetic/immunofluorescence assay (CellSearch™). A round-robin concordance project was done between Mayo Clinic Rochester and Institut Jules Bordet before embarking on the primary correlative work.

Results: At baseline, 20% pts had detectable (i.e., ≥1) EpCAM+/CK+/DAPI+/CD45- CTCs, and 16% pts had detectable EpCAM+/CK+/DAPI+/CD45-/HER2+ CTCs. Correlative analyses with clinical outcome are ongoing with plans for completion by Fall 2014.

Conclusions: CTCs were detected in 20% of pts with HER2+ early stage breast cancer. This is similar to the frequency of detection in mixed early stage breast cancer populations relative to ER/PR and HER2 status. Concordance of enumeration and HER2 assessments between the two experienced laboratories, and correlation between disease free survival and CTC findings (from serial samples collected at baseline, during the course of HER2 directed therapy, and at set intervals of follow-up) will be reported.

Citation Format: Minetta C Liu, Brigitte Rack, Amylou C Dueck, David W Hillman, Michael B Campion, Monica M Reinholz, Kevin C Halling, Christos Sotiriou, Françoise Rothé, Marion Maetens, Ghizlane Rouas, Wolfgang Janni, Antonio C Wolff, Lyndsay N Harris, Julie R Gralow, Kathleen I Pritchard, Susan Ellard, Nguyet A Le-Lindqwister, Frances Boyle, Evandro De Azambuja, Martine J Piccart-Gebhart, Michail Ignatiadis, Edith A Perez. Circulating tumor cell (CTC) enumeration and HER2 assessment as predictors of breast cancer outcomes in the ALTTO (BIG 2-06, Alliance N063D) 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 P4-01-01.

Benefit to neoadjuvant anti-human epidermal growth factor receptor 2 (HER2)-targeted therapies in HER2-positive primary breast cancer is independent of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) status

BACKGROUND

Assessment of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) might be an important tool in identifying human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients unlikely to derive benefit from anti-HER2 therapies. However, studies to date have failed to demonstrate its predictive role in any treatment setting.

PATIENTS AND METHODS

Prospectively collected baseline core biopsies from 429 early-stage HER2-positive breast cancer patients treated with trastuzumab, lapatinib, or their combination in the Neo-ALTTO study were stained using two anti-PTEN monoclonal antibodies (CST and DAKO). The association of PTEN status and PI3K pathway activation (defined as either PTEN loss and/or PIK3CA mutation) with total pathological complete response (tpCR) at surgery, event-free survival (EFS), and overall survival (OS) was evaluated.

RESULTS

PTEN loss was observed in 27% and 29% of patients (all arms, n = 361 and n = 363) for CST and DAKO, respectively. PTEN loss was more frequently observed in hormone receptor (HR)-negative (33% and 36% with CST and DAKO, respectively) compared with HR-positive tumours (20% and 22% with CST and DAKO, respectively). No significant differences in tpCR rates were observed according to PTEN status. PI3K pathway activation was found in 47% and 48% of patients (all arms, n = 302 and n = 301) for CST and DAKO, respectively. Similarly, tpCR rates were not significantly different for those with or without PI3K pathway activation. Neither PTEN status nor PI3K pathway activation were predictive of tpCR, EFS, or OS, independently of treatment arm or HR status. High inter-antibody and inter-observer agreements were found (>90%). Modification of scoring variables significantly affected the correlation between PTEN and HR status but not with tpCR.

CONCLUSION

These data show that PTEN status determination is not a useful biomarker to predict resistance to trastuzumab and lapatinib-based therapies. The lack of standardization of PTEN status determination may influence correlations between expression and relevant clinical end points.

CLINICAL TRIALS

This trial is registered with ClinicalTrials.gov: NCT00553358.

Trastuzumab-Associated Cardiac Events at 8 Years of Median Follow-Up in the Herceptin Adjuvant Trial (BIG 1-01)

Purpose

To document the rate and outcome of trastuzumab-associated cardiac dysfunction in patients following 1 or 2 years of adjuvant therapy.

Patients and Methods

The Herceptin Adjuvant (HERA) trial is a three-arm, randomized trial comparing 2 years or 1 year of trastuzumab with observation in 5,102 patients with human epidermal growth factor receptor 2 (HER2) –positive early-stage breast cancer. Cardiac function was closely monitored. Eligible patients had left ventricular ejection fraction (LVEF) ≥ 55% at study entry following neoadjuvant chemotherapy with or without radiotherapy. This 8-year median follow-up analysis considered patients randomly assigned to 2 years or 1 year of trastuzumab or observation.

Results

The as-treated safety population for 2 years of trastuzumab (n = 1,673), 1 year of trastuzumab (n = 1,682), and observation (n = 1,744) is reported. Cardiac adverse events leading to discontinuation of trastuzumab occurred in 9.4% of patients in the 2-year arm and 5.2% of patients in the 1-year arm. Cardiac death, severe congestive heart failure (CHF), and confirmed significant LVEF decrease remained low in all three arms. The incidence of severe CHF (0.8%, 0.8%, and 0.0%, respectively) and confirmed significant LVEF decrease (7.2%, 4.1%, and 0.9%, respectively) was significantly higher in the 2-year and 1-year trastuzumab arms compared with the observation arm. Severe CHF was the same for 2-year and 1-year trastuzumab. Of patients with confirmed LVEF decrease receiving 2-year trastuzumab, 87.5% reached acute recovery. Of patients with confirmed LVEF decrease receiving 1-year trastuzumab, 81.2% reached acute recovery.

Conclusion

Long-term assessment at 8-year median follow-up confirms the low incidence of cardiac events for trastuzumab given sequentially after chemotherapy and radiotherapy, and cardiac events were reversible in the vast majority of patients.

First results from the phase III ALTTO trial (BIG 2-06; NCCTG [Alliance] N063D) comparing one year of anti-HER2 therapy with lapatinib alone (L), trastuzumab alone (T), their sequence (T→L), or their combination (T+L) in the adjuvant treatment of HER2-positive early breast cancer (EBC)

LBA4

Background: Lapatinib (L) is a HER1-HER2 tyrosine kinase inhibitor. The Adjuvant Lapatinib and/or Trastuzumab Treatment Optimisation (ALTTO) Trial is a randomised, phase III trial comparing 3 oral L-containing regimens with T, each given for 1 year. Methods: From June 2007 to July 2011, 8381 patients (pts) were randomised from 946 sites in 44 countries to receive either L+T, T→L, L, or T. Anti-HER2 therapy was initiated after completing all chemotherapy (N=4613), concurrently with a taxane following anthracycline (N=3337), or concurrently with a non-anthracycline, platinum-containing regimen (N=431). The L arm was closed in Aug 2011 for futility and is not presented. The primary endpoint is invasive disease-free survival (DFS). L+T vs. T is tested for superiority and T→L vs. T is tested for non-inferiority at 1.11 margin. P≤0.025 is required for statistical significance. 850 DFS events in the L+T vs. T comparison would provide 80% power to detect a true hazard ratio (HR) of 0.80 with experiment-wide alpha=0.05. The current analysis was planned to occur either after observing these 850 events or at 4.5 yrs median follow up (MFU). Results: Pt and disease characteristics were well balanced. 40% were node-negative and 57% were hormone receptor positive. Only 555 DFS events for the L+T vs. T comparison were observed at 4.5 years MFU. HR for DFS was 0.84 (97.5% CI, 0.70-1.02; P=0.048; 4-yr DFS%=88% vs. 86%) for L+T vs. T and 0.93 (97.5% CI, 0.76-1.13; non-inferiority P=0.044; 4-yr DFS%=87% vs. 86%) for T→L vs. T. Diarrhoea (75% vs. 20%), rash (55% vs. 20%) and hepatobiliary (23% vs. 16%) adverse events were more frequent in L+T vs. T. Primary cardiac endpoints were infrequent (<1%) in all arms. Conclusions: L+T has lower risk of a DFS event compared with T, and T→L appeared non-inferior to T, but neither finding was statistically significant. The first DFS results of dual HER2 blockade in the adjuvant ALTTO at 4.5 years MFU are unexpected considering the effect shown by doubling the pCR rate with L+T vs. T in the NeoALLTO trial. Follow up continues. Clinical trial information: NCT00490139.