Talazoparib versus chemotherapy in patients with germline BRCA1/2-mutated HER2-negative advanced breast cancer: final overall survival results from the EMBRACA trial

BACKGROUND

In EMBRACA, talazoparib prolonged progression-free survival versus chemotherapy (hazard ratio [HR] 0.542 [95% confidence interval (CI) 0.413-0.711]; P < 0.0001) and improved patient-reported outcomes (PRO) in germline BRCA1/2 (gBRCA1/2)-mutated advanced breast cancer (ABC). We report final overall survival (OS).

PATIENTS AND METHODS

This randomized phase III trial enrolled patients with gBRCA1/2-mutated HER2-negative ABC. Patients received talazoparib or physician's choice of chemotherapy. OS was analyzed using stratified HR and log-rank test and prespecified rank-preserving structural failure time model to account for subsequent treatments.

RESULTS

A total of 431 patients were entered in a randomized study (287 talazoparib/144 chemotherapy) with 412 patients treated (286 talazoparib/126 chemotherapy). By 30 September 2019, 216 deaths (75.3%) occurred for talazoparib and 108 (75.0%) chemotherapy; median follow-up was 44.9 and 36.8 months, respectively. HR for OS with talazoparib versus chemotherapy was 0.848 (95% CI 0.670-1.073; P = 0.17); median (95% CI) 19.3 months (16.6-22.5 months) versus 19.5 months (17.4-22.4 months). Kaplan-Meier survival percentages (95% CI) for talazoparib versus chemotherapy: month 12, 71% (66% to 76%)/74% (66% to 81%); month 24, 42% (36% to 47%)/38% (30% to 47%); month 36, 27% (22% to 33%)/21% (14% to 29%). Most patients received subsequent treatments: for talazoparib and chemotherapy, 46.3%/41.7% received platinum and 4.5%/32.6% received a poly(ADP-ribose) polymerase (PARP) inhibitor, respectively. Adjusting for subsequent PARP and/or platinum use, HR for OS was 0.756 (95% bootstrap CI 0.503-1.029). Grade 3-4 adverse events occurred in 69.6% (talazoparib) and 64.3% (chemotherapy) patients, consistent with previous reports. Extended follow-up showed significant overall improvement and delay in time to definitive clinically meaningful deterioration in global health status/quality of life and breast symptoms favoring talazoparib versus chemotherapy (P < 0.01 for all), consistent with initial analyses.

CONCLUSIONS

In gBRCA1/2-mutated HER2-negative ABC, talazoparib did not significantly improve OS over chemotherapy; subsequent treatments may have impacted analysis. Safety was consistent with previous observations. PRO continued to favor talazoparib.

Abstract PD3-11: HER2/ERBB2 status in “HER2 equivocal” breast cancers by FISH and ASCO-CAP guidelines: False-positives due to heterozygous deletions of alternative control loci

Background. The ASCO-CAP guidelines for HER2 testing by fluorescence in situ hybridization (FISH) have a category, referred to as “equivocal” (average HER2 copies per tumor cell &gt;4-6 with HER2/CEP17 ratio &lt;2·0), which is neither “HER2-positive” nor “HER2-negative”. Approximately 4% - 12% of invasive breast cancers are “HER2-equivocal” based on FISH. Cancers in this category may be resolved as “negative” or “positive” by FISH alternative control probes (2013/2014 guidelines) or HER2 immunohistochemistry (IHC) (2018 update). Our objectives were to evaluate the following hypotheses: 1.) Genetic loci used as alternative controls show heterozygous deletion in a substantial proportion of breast cancers; 2.) Use of these loci for assessment of HER2 by FISH leads to false-positives; 3.) HER2 FISH false-positive breast cancer patients have outcomes that do not differ from clinical outcomes for HER2-negative breast cancer patients; and 4.) HER2-equivocal breast cancers seldom show HER2 protein overexpression (IHC 3+).

Methods. We retrospectively assessed the use of chromosome 17 p-arm and q-arm alternative control genomic sites (TP53, D17S122, SMS, RARA, TOP2A), as recommended by the 2013/2014 ASCO-CAP guidelines, in patients whose data were available through the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC)(N=1980) or whose tissues were available from the BCIRG-005 clinical trial (N=3298). We used either FDA-approved HER2 IHC (HercepTest) or laboratory-developed HER2 (10H8) IHC assays to assess HER2 protein expression.

Results. Using METABRIC we found heterozygous deletions, particularly in specific p-arm sites, were common in both HER2-amplified and HER2-not-amplified breast cancers. Use of alternative control probes from these regions to assess HER2 by FISH in “HER2 equivocal” as well as HER2-not-amplified breast cancers resulted in high rates of false-positive ratios (HER2-to-alternative control ratio &gt;2·0) due to heterozygous deletions of control p-arm genomic sites used as ratio denominators. Misclassifications of HER2 status was observed not only in breast cancers with ASCO-CAP “equivocal” status but also in breast cancers with an average of &lt;4·0 HER2 copies per tumor cell. These deletions were also identified by FISH. IHC demonstrated &lt;1% of FISH “HER2-equivocal” breast cancers in BCIRG-005 had IHC3+ immunostaining, consistent with HER2-not-amplified status. Clinical outcomes of “HER2-equivocal” breast cancer patients with HER2-to-alternative control ratio &gt;2·0 did not differ significantly from clinical outcomes of those with HER2-to-alternative control ratio&lt;2·0.

Conclusion. Using chromosome 17 p-arm alternative controls, as recommended by 2013/2014 ASCO-CAP guidelines, instead of CEP17 for resolution of “HER2 equivocal” cases, is problematic due to frequent heterozygous deletions of these loci in breast cancers. The indiscriminate use of alternative control probes to calculate a HER2 FISH ratio in “HER2-equivocal” breast cancers leads to false-positive interpretations of HER2 status resulting from unrecognized heterozygous deletions in one or more of these alternative control genomic sites and incorrect HER2 ratio determinations.

Citation Format: Press MF, Seoane JA, Curtis C, Quinaux E, Guzman R, Sauter G, Eiermann W, Mackey JR, Robert N, Pienkowski T, Crown J, Martin M, Valero V, Bee V, Ma Y, Villalobos I, Slamon DJ. HER2/ERBB2 status in “HER2 equivocal” breast cancers by FISH and ASCO-CAP guidelines: False-positives due to heterozygous deletions of alternative control loci [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD3-11.

Abstract OT2-01-13: A phase 3, open-label, randomized, 2-arm international study of the oral dual PARP inhibitor talazoparib in germline BRCA mutation subjects with locally advanced and/or metastatic breast cancer (EMBRACA)

Background: Cancer cells with deleterious mutations in breast cancer susceptibility genes 1 and 2 (BRCA1/2) are deficient in the DNA double-strand break repair mechanism, rendering them highly dependent on the single-strand break repair pathway, regulated by poly(ADP-ribose) polymerase (PARP). Inhibition of PARP results in synthetic lethality in cells with a BRCA1/2 mutation because of accumulation of irreparable DNA damage; PARP inhibitors have the potential to be selectively toxic for BRCA-mutated cells. In addition to catalytic inhibition, it has been shown that some PARP inhibitors induce PARP trapping at sites of DNA damage. The capacity to trap PARP-DNA complexes varies widely across different PARP inhibitors and is not correlated with PARP catalytic inhibition. Preclinical models have shown trapping PARP on DNA is more potent at inducing cancer cell death than enzymatic inhibition of PARP alone. Talazoparib is a dual-mechanism PARP inhibitor that both inhibits the PARP enzyme and effectively traps PARP on DNA, preventing DNA damage repair and resulting in cell death in BRCA1/2-mutated cells. In preclinical studies, talazoparib at nanomolar concentrations showed the highest efficiency at trapping PARP-DNA complexes relative to other PARP inhibitors. In a previous phase 1/2 clinical study, talazoparib as monotherapy (1 mg once daily) resulted in a 50% response rate and an 86% clinical benefit rate at 24 weeks in 14 patients with a germline BRCA1/2 mutation and advanced breast cancer (aBC).

Methods: This open-label, randomized, 2-arm, international phase 3 trial (EMBRACA)

compares the efficacy and safety of talazoparib with protocol-specific physician's choice (capecitabine, eribulin, gemcitabine or vinorelbine) in patients with aBC. The primary objective is progression-free survival by central imaging. Secondary objectives are objective response rate, overall survival, safety and pharmacokinetics of talazoparib. Exploratory objectives include health-related quality of life measurements and biomarker research in blood and tumor samples that may permit characterization of mechanisms involved in tumor sensitivity and resistance to talazoparib. Key patient eligibility criteria include aged ≥18 years with histologically/cytologically confirmed breast cancer; locally advanced and/or metastatic disease appropriate for systemic single-agent cytotoxic chemotherapy; deleterious or pathogenic germline BRCA1/2 mutations by central laboratory; ≤3 prior cytotoxic chemotherapy regimens for advanced disease (prior platinum is allowed provided patients did not relapse within 6 months in the adjuvant setting or did not progress on platinum therapy); prior treatment with a taxane and/or anthracycline unless medically contraindicated; and ECOG performance status ≤2. Patients (N=429) will be randomized 2:1 to receive either talazoparib capsules (1 mg/day, 21-day cycles) or physician's choice treatment. This trial is currently enrolling patients from the USA, Europe, Israel, Ukraine, Russia, Korea, Australia, Taiwan and Brazil (NCT01945775).

This study is funded by Medivation, Inc.

Citation Format: Litton J, Ettl J, Hurvitz SA, Mina LA, Rugo HS, Lee K-H, Yerushalmi R, Woodward N, Goncalves A, Moreno F, Roche H, Im Y-H, Martin M, Bhattacharya S, Peterson A, Hannah A, Eiermann W, Blum J. A phase 3, open-label, randomized, 2-arm international study of the oral dual PARP inhibitor talazoparib in germline BRCA mutation subjects with locally advanced and/or metastatic breast cancer (EMBRACA) [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 OT2-01-13.

Long-term outcomes after adjuvant treatment of sequential versus combination docetaxel with doxorubicin and cyclophosphamide in node-positive breast cancer: BCIRG-005 randomized trial

BACKGROUND

The optimal regimen for adjuvant breast cancer chemotherapy is undefined. We compared sequential to concurrent combination of doxorubicin and cyclophosphamide with docetaxel chemotherapy in women with node-positive non-metastatic breast cancer. We report the final, 10-year analysis of disease-free survival (DFS), overall survival (OS), and long-term safety.

PATIENTS AND METHODS

A total of 3298 women with HER2 nonamplified breast cancer were randomized to doxorubicin and cyclophosphamide every 3 weeks for four cycles followed by docetaxel (AC → T) every 3 weeks for four cycles or docetaxel, doxorubicin, and cyclophosphamide (TAC) every 3 weeks for six cycles. The patients received standard radiotherapy and endocrine therapy and were followed up for 10 years with annual clinical evaluation and mammography.

RESULTS

The 10-year DFS rates were 66.5% in the AC → T arm and 66.3% in the TAC arm (P = 0.749). OS was 79.9% in the AC → T arm and 78.9% in the TAC arm (P = 0.506). TAC was associated with higher rates of febrile neutropenia, although G-CSF primary prophylaxis greatly reduced this risk. AC → T was associated with a higher rate of myalgia, hand-foot syndrome, fluid retention, and sensory neuropathy.

CONCLUSION

This 10-year analysis of the BCIRG-005 trial confirmed that the efficacy of TAC was not superior to AC → T in women with node-positive early breast cancer. The toxicity profiles differ between arms and were consistent with previous reports. The TAC regimen with G-CSF support provides shorter adjuvant treatment duration with less toxicity.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT00312208.

Abstract S6-03: Anastrozole versus tamoxifen for the prevention of loco-regional and contralateral breast cancer in postmenopausal women with locally excised ductal carcinoma in-situ (IBIS-II DCIS)

Background: Third generation aromatase inhibitors are a more effective treatment option than tamoxifen for hormone receptor positive invasive breast cancer in postmenopausal women. However, it is not known whether anastrozole is more effective than tamoxifen in preventing the recurrence of breast cancer in women with hormone receptor (HR) positive ductal carcinoma in situ (DCIS). Here, we compare the efficacy of anastrozole versus tamoxifen in postmenopausal women with HR positive DCIS.

Methods: A multi-centre randomised placebo-controlled trial of 1mg/day anastrozole (oral) vs. 20mg/day tamoxifen (oral) for five years was conducted in 2980 postmenopausal women with locally excised HR positive DCIS. The primary endpoint was to determine if anastrozole is at least as effective as tamoxifen in loco-regional control and prevention of contralateral disease. Secondary endpoints included breast cancer mortality, other cancers, cardiovascular disease, fractures, adverse events and non-breast cancer deaths. All analyses were done on an intention-to-treat basis and Cox proportional hazard were used to compute hazard ratios and corresponding confidence intervals for recurrence.

Results: Between 2003 and 2012, a total of 2980 postmenopausal women were recruited into the IBIS-II DCIS trial. 1471 women were randomly assigned to receive anastrozole and 1509 women tamoxifen. Median follow-up for this first analysis is 6.8 years and 131 breast cancer recurrences have been recorded. Median age was 60.3 years (56.1-64.6), median BMI was 26.7 (23.6-30.7), and 45.6% of women had used hormone replacement therapy (HRT) before joining the trial. Of the 131 women with recurrent disease, 77 had a loco-regional recurrence and 51 reported contralateral disease. A total of 61 deaths were recorded. We will present a comprehensive analysis of the efficacy of anastrozole and tamoxifen for preventing loco-regional/contralateral breast cancer and major adverse events by intention to treat (ITT).

Conclusions: To follow.

Citation Format: Cuzick J, Forbes JF, Sestak I, Howell A, Bonanni B, Bundred N, Levy C, von Minckwitz G, Eiermann W, Neven P, Stierer M, Holcombe C, Coleman RE, Jones LJ, Ellis I. Anastrozole versus tamoxifen for the prevention of loco-regional and contralateral breast cancer in postmenopausal women with locally excised ductal carcinoma in-situ (IBIS-II DCIS). [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 S6-03.

Abstract P1-13-04: Higher rate of severe toxicities in obese patients receiving dose-dense chemotherapy according to unadjusted body mass index – Results of the prospectively randomized GAIN study

Background: In routine clinical practice chemotherapy (CT) doses are frequently capped at a body surface area (BSA) of 2.0 m2 or adjusted to an ideal weight (i.e. [body length in cm - 10%] + 40% [current weight-ideal weight]) for obese patients (BMI&gt;30 according to WHO) due to safety reasons. There are no data on CT dosing within intense dose-dense regimen for obese patients. Therefore, a retrospective analysis of the GAIN study population has been conducted.

Methods: Between August 2004 and July 2008 a total of 3023 patients were enrolled in the GAIN study, a randomized phase III adjuvant trial, comparing two types of dose-dense regimen. Patients were randomized to intense dose-dense ETC (Epirubicin 150 mg/m2, Paclitaxel 225 mg/m2, Cyclophosphamide 2500-2000 mg/m2, i.v. q15 for 3 cycles) or EC followed by T plus capecitabine (X) (EC-TX) (E 112.5 mg/m2 + C 600 mg/m2, i.v. q15 for 4 cycles followed by T 67.5 mg/m2 i.v. q8 for 10 weeks + X: 2000 mg/m2 p. o. day 1-14, q22 for 4 cycles). An adjustment of CT dose to an ideal weight for obese patients was implemented by a protocol amendment. Yet some patients received a dose adjustment by capping at 2.0 m2. We retrospectively evaluated a total of 543 patients with a BMI&gt;30. Data on BSA and dose adjustment were collected from case report forms. Toxicities were compared between patients who received CT according to an unadjusted or adjusted BSA using the 2-sided exact test of Fisher. Disease-free survival (DFS) and overall survival (OS) were calculated using the Kaplan-Meier method and the log-rank test.

Results: Overall, 18.0% (n=543) of patients in the GAIN study were obese: 30.9% (n=168) of them received CT according to an unadjusted BSA. For the remainder BSA was adjusted to ideal weight or was capped at 2.0 m2 (69.1%; n=375). A total of 14.5% (n=24) of obese patients receiving full dose of chemotherapy vs 6.4% (n=24) of obese patients with an adjusted BSA experienced febrile neutropenia (p=0.005) and 9.6% (n=16) vs 2.9% (n=11) high grade thrombopenia (p=0.002). Overall, 16.7% (n=28) vs 10.1% (n=38) had a thromboembolic event (p=0.034), which was high grade in 12.5% (n=21) vs 6.4% (n=24), respectively (p=0.027) and 3.0% (n=5) vs 0.3% (n=1) experienced high grade hot flushes (p=0.012). The only significant differences in favor of the non-adjusted group were for dizziness (4.2% [n=7] vs 10.7% [n=40]; p=0.013), diarrhea (18.5% [n=31] vs 26.9% [n=101]; p=0.039) and an increase in serum creatinine (6.8% [n=11] vs 14.0% [n=52]; p=0.019). No differences in DFS and OS were observed between the two groups (5year DFS 81.9% [CI 74.9%-87.2%] vs 80.8% [76.3%-84.6%]; p=0.850; 5year OS 86.4% [79.9%-90.9%] vs 88.3% [84.4%-91.3%]; p=0.491).

Conclusion: This analysis of patients treated with a dose-dense regimen showed that obese patients who received CT according to their real BSA have a higher risk of severe toxicities, in particular of febrile neutropenia, high grade thrombopenia and high grade thromboembolic events. Therefore, a dose adjustment of intense dose-dense CT should be performed for obese patients to avoid life-threatening complications.

Citation Format: Furlanetto J, Eiermann W, Marmé F, Reimer T, Reinisch M, Schmatloch S, Stickeler E, Thomssen C, Untch M, Denkert C, von Minckwitz G, Nekljudova V, Loibl S, Möbus V. Higher rate of severe toxicities in obese patients receiving dose-dense chemotherapy according to unadjusted body mass index – Results of the prospectively randomized GAIN study. [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 P1-13-04.

Abstract P6-03-09: Genetic polymorphism and correlation with treatment induced cardiotoxicity and prognosis in HER2 amplified early breast cancer patients

Introduction: Small studies have indicated a possible correlation between a HER2 gene polymorphism at codon 655 and trastuzumab-associated cardiotoxicity. Association between a synonymous coding variant rs7853758 within the SLC28A3 gene and anthracycline induced cardiotoxicity has also been reported. This study aimed to validate these correlations and assess for any relationship with prognosis.

Methods: Genomic DNA was isolated from 666 patients enrolled in a large trial of adjuvant chemotherapy in HER2 amplified early breast cancer (BCIRG 006). Genotyping was conducted using Sequenom MassARRAY System for HER2 G-&gt;A polymorphism at amino acid codon 655 (rs1136201) and variant rs7853758 (L461L) within the SLC28A3 gene.

Results: Of the 666 patients analyzed, 216 patients were treated with anthracycline based therapy, 226 with trastuzumab based therapy, and 224 with regimens containing both an anthracycline and trastuzumab. Compared with the overall results of the BCIRG006 study (N=3,222), in the subset of patients genotyped in this analysis, a less robust improvement in disease free survival (DFS) was observed for the trastuzumab arms than control arm (HR, 0.821). When stratified for prognostic features, the hazard ratio in favor of trastuzumab was consistent with that of the overall study (HR, 0.674). Samples from 662 patients were successfully genotyped for rs1136201. Of these, 424 (64%) were AA, 30 (4.5%) were GG, 208 (31%) were AG genotype. Samples from 665 patients were successfully genotyped for rs7853758. Of these, 19 (3%) were AA, 475 (71%) were GG, and 171 (26%) were AG genotype. There was no correlation seen between mean left ventricular ejection fraction (LVEF) and HER2 genotype at codon 655 in patients treated with trastuzumab. Of patients tested for the HER2 polymorphism, cardiac dysfunction [defined as &gt; 10% decline in LVEF or clinical congestive heart failure (CHF)] developed in 16% of patients with AA, 17% of patients with GG and 20% of patients with AG. There was also no correlation between mean LVEF and variant rs7853758 in patients treated with anthracyclines. The percentage of patients who developed cardiac dysfunction was 13%, 17% and 21% in AA, GG, and AG genotypes respectively. No correlation between disease free survival and any of the genotypes was seen.

Conclusion: In the largest analysis to date to evaluate for relationship between cardiac toxicity and HER2 polymorphism, we did not find a correlation with rs1136201 HER2 polymorphism and trastuzumab induced cardiac toxicity. Our study also did not show a correlation between variant rs7853758 (L461L) and anthracycline induced cardiotoxicity. Neither polymorphism correlated with prognosis.

Citation Format: Peddi PF, Hurvitz SA, Fasching PA, Wang L, Cunningham J, Weinshilboum RM, Liu D, Quinaux E, Fourmanoir H, Robert NJ, Valero V, Crown J, Falkson C, Brufsky A, Pienkowski T, Eiermann W, Martin M, Bee V, Slamon DJ. Genetic polymorphism and correlation with treatment induced cardiotoxicity and prognosis in HER2 amplified early breast cancer patients. [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 P6-03-09.

Statistical controversies in clinical research: statistical significance-too much of a good thing …

The use and interpretation of P values is a matter of debate in applied research. We argue that P values are useful as a pragmatic guide to interpret the results of a clinical trial, not as a strict binary boundary that separates real treatment effects from lack thereof. We illustrate our point using the result of BOLERO-1, a randomized, double-blind trial evaluating the efficacy and safety of adding everolimus to trastuzumab and paclitaxel as first-line therapy for HER2+ advanced breast cancer. In this trial, the benefit of everolimus was seen only in the predefined subset of patients with hormone receptor-negative breast cancer at baseline (progression-free survival hazard ratio = 0.66, P = 0.0049). A strict interpretation of this finding, based on complex 'alpha splitting' rules to assess statistical significance, led to the conclusion that the benefit of everolimus was not statistically significant either overall or in the subset. We contend that this interpretation does not do justice to the data, and we argue that the benefit of everolimus in hormone receptor-negative breast cancer is both statistically compelling and clinically relevant.

Zoledronic acid combined with adjuvant endocrine therapy of tamoxifen versus anastrozol plus ovarian function suppression in premenopausal early breast cancer: final analysis of the Austrian Breast and Colorectal Cancer Study Group Trial 12

BACKGROUND

Zoledronic acid (ZOL) plus adjuvant endocrine therapy significantly improved disease-free survival (DFS) at 48- and 62-month follow-up in the ABCSG-12 trial. We present efficacy results of a final additional analysis after 94.4 months.

PATIENTS AND METHODS

Patients were premenopausal women who had undergone primary surgery for stage I/II estrogen-receptor-positive and/or progesterone-receptor-positive breast cancer with <10 positive lymph nodes, and were scheduled for standard goserelin therapy. All 1803 patients received goserelin (3.6 mg every 28 days) and were randomized to tamoxifen (20 mg/days) or anastrozole (1 mg/days), both with or without ZOL (4 mg every 6 months) for 3 years. The primary end point was DFS; recurrence-free survival and overall survival (OS) were secondary end points.

RESULTS

After 94.4-month median follow-up (range, 0-114 months), relative risks of disease progression [hazard ratio (HR) = 0.77; 95% confidence interval (CI) 0.60-0.99; P = 0.042] and of death (HR = 0.66; 95% CI 0.43-1.02; P = 0.064) are still reduced by ZOL although no longer significant at the predefined significance level. Overall, 251 DFS events and 86 deaths were reported. Absolute risk reductions with ZOL were 3.4% for DFS and 2.2% for OS. There was no DFS difference between tamoxifen alone versus anastrozole alone, but there was a pronounced higher risk of death for anastrozole-treated patients (HR = 1.63; 95% CI 1.05-1.45; P = 0.030). Treatments were generally well tolerated, with no reports of renal failure or osteonecrosis of the jaw.

CONCLUSION

These final results from ABCSG 12 suggest that twice-yearly ZOL enhances the efficacy of adjuvant endocrine treatment, and this benefit is maintained long-term.

CLINICALTRIALSGOV

NCT00295646 (http://www.clinicaltrials.gov/ct2/results?term=00295646).

Ki67 levels as predictive and prognostic parameters in pretherapeutic breast cancer core biopsies: a translational investigation in the neoadjuvant GeparTrio trial

BACKGROUND

The proliferation marker Ki67 has been suggested as a promising cancer biomarker. As Ki67 needs an exact quantification, this marker is a prototype of a new generation of tissue-based biomarkers. In this study, we have systematically evaluated different cut points for Ki67 using three different clinical end points in a large neoadjuvant study cohort.

PATIENTS AND METHODS

We have evaluated pretherapeutic Ki67 levels by immunohistochemistry in 1166 breast cancer core biopsies from the neoadjuvant GeparTrio trial. We used the standardized cutoff-finder algorithm for three end points [response to neoadjuvant chemotherapy (pCR), disease-free (DFS) and overall-survival (OS)]. The analyses were stratified for hormone receptor (HR) and HER2 status by molecular subtype radar diagrams (MSRDs).

RESULTS

A wide range of Ki67 cut points between 3%-94% (for pCR), 6%-46% (for DFS) and 4%-58% (for OS) were significant. The three groups of Ki67 ≤ 15% versus 15.1%-35% versus >35% had pCR-rates of 4.2%, 12.8%, and 29.0% (P < 0.0005), this effect was also present in six of eight molecular subtypes. In MSRD, Ki67 was significantly linked to prognosis in uni- and multivariate analysis in the complete cohort and in HR-positive, but not triple-negative tumors.

CONCLUSIONS

Ki67 is a significant predictive and prognostic marker over a wide range of cut points suggesting that data-derived cut point optimization might not be possible. Ki67 could be used as a continuous marker; in addition, the scientific community could define standardized cut points for Ki67. Our analysis explains the variability observed for Ki67 cut points in previous studies; however, this should not be seen as weakness, but as strength of this marker. MSRDs are an easy new approach for visualization of biomarker effects on outcome across molecular subtypes in breast cancer. The experience with Ki67 could provide important information regarding the development and implementation of other quantitative biomarkers.

Using the 21-gene assay to guide adjuvant chemotherapy decision-making in early-stage breast cancer: a cost-effectiveness evaluation in the German setting

OBJECTIVE

The 21-gene assay (Oncotype DX Breast Cancer Test (Genomic Health Inc., Redwood City, CA)) is a well validated test that predicts the likelihood of adjuvant chemotherapy benefit and the 10-year risk of distant recurrence in patients with ER+, HER2- early-stage breast cancer. The aim of this analysis was to evaluate the cost-effectiveness of using the assay to inform adjuvant chemotherapy decisions in Germany.

METHODS

A Markov model was developed to make long-term projections of distant recurrence, survival, quality-adjusted life expectancy, and direct costs for patients with ER+, HER2-, node-negative, or up to 3 node-positive early-stage breast cancer. Scenarios using conventional diagnostic procedures or the 21-gene assay to inform treatment recommendations for adjuvant chemotherapy were modeled based on a prospective, multi-center trial in 366 patients. Transition probabilities and risk adjustment were based on published landmark trials. Costs (2011 Euros (€)) were estimated from a sick fund perspective based on resource use in patients receiving chemotherapy. Future costs and clinical benefits were discounted at 3% annually.

RESULTS

The 21-gene assay was projected to increase mean life expectancy by 0.06 years and quality-adjusted life expectancy by 0.06 quality-adjusted life years (QALYs) compared with current clinical practice over a 30-year time horizon. Clinical benefits were driven by optimized allocation of adjuvant chemotherapy. Costs from a healthcare payer perspective were lower with the 21-gene assay by ∼€561 vs standard of care. Probabilistic sensitivity analysis indicated that there was an 87% probability that the 21-gene assay would be dominant (cost and life saving) to standard of care.

LIMITATIONS

Country-specific data on the risk of distant recurrence and quality-of-life were not available.

CONCLUSIONS

Guiding decision-making on adjuvant chemotherapy using the 21-gene assay was projected to improve survival, quality-adjusted life expectancy, and be cost saving vs the current standard of care women with ER+, HER2- early-stage breast cancer.

Abstract PD06-01: Automated computational Ki67 scoring in the GeparTrio breast cancer study cohort

Background: Scoring proliferation through Ki67-immunohistochemistry is an important component in predicting therapy response to chemotherapy in breast cancer patients. Therefore, an accurate and standardized Ki67-scoring is pivotal both in routine diagnostics and larger multi-center studies aiming at improving present or establishing new cut-off values for existing or novel therapy regimens. However, recent studies have cast some doubt on the reliability of “visual” Ki67 scoring by pathologists, especially within the lower - yet clinically important - proliferation range. Here, we present and apply a novel automated image analysis approach for Ki67-quantification in breast cancer tissue.

Methods: We perform automated Ki67-scoring in 1219 breast cancer patients from the GeparTrio study cohort using a novel image analysis approach that avoids detection biases due to morphological variability by using a generic minimum-model approach. The method is capable of tumor-stroma-separation and may be used to process large data sets fully unsupervised in batch mode while allowing for efficient visual checks of the results. We compare these results with a different in-house-developed subtiling-based automated quantification method and moreover, gauge our approach with manual scoring performed by pathologists.

Results: The results show deviations of 10% (automated method 1 vs. manual), 9% (automated method 2 vs. manual) and 3% (automated method 1 vs. automated method 2) on average. The Ki67 scores show Pearson correlations between automated and manual scoring of r&gt;0.8 (p &lt; 0.001) for both automated methods and r&gt;0.95 (p &lt; 0.001) between the two tested automated methods.

Conclusion: Because of the methodological differences of the presented techniques our results suggest a high robustness of the automated methods that at the same time show a good agreement with manual Ki67 scoring. Our approach therefore offers an automated and standardized means of Ki67 quantification applicable in routine diagnostics as well as larger clinical study settings, such as in the GeparTrio cohort shown here.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD06-01.

Abstract S4-5: Ki67 levels in pretherapeutic core biopsies as predictive and prognostic parameters in the neoadjuvant GeparTrio trial

Background: Ki67 has been suggested as a marker for definition of luminal A and luminal B tumors by the 2011 St. Gallen consensus panel. However, the cutoffs for Ki67 are still under debate. In particular, it is not clear if one single cutoff is useful for prognostic and predictive information in the different molecular subtypes. It is an advantage of the neoadjuvant approach that predictive and prognostic outcome measurements can be separated in the same cohort. In this study, we evaluated a large cohort of core biopsies from the neoadjuvant GeparTrio trial to investigate the impact of pretherapeutic Ki67 levels as a predictive marker for response to neoadjuvant chemotherapy as well as a prognostic marker for progression-free and overall survival. The analysis was stratified for hormone-receptor positive and negative tumors as well as HER2 status.

Methods: A total of 1166 pretherapeutic core biopsies from the neoadjuvant Gepartrio trial were evaluated for Ki67 by immunohistochemistry, a total of 200 cells were counted in each sample. Ki67 cutoffs were evaluated using web-based software Cutoff Finder (http://molpath.charite.de/cutoff/). The details of the GeparTrio study design have been described before (von Minckwitz, JNCI 2008). We compared pCR rate as well as the overall and disease free survival in the complete cohort as well as subgroups of patients based on hormone receptor and HER2 expression.

Results: Using Ki67 as a continuous parameter, a wide range of cutoffs between 10% and 80% for Ki67 were predictive for pCR. For DFS and OS, a wide range of cutoffs between 10% and 45% was significant. For further analysis, the three groups of Ki67 0–15% vs. Ki67 15.1%–35% vs. Ki67 &gt;35 were defined and were compared for different outcome parameters. The pCR rates in these three groups of Ki67 expression were 4.2%, 12.9% and 29.0% (p &lt; 0.0005). For DFS and OS, the groups were significantly linked to prognosis in univariate and multivariate analysis. A detailed subgroup analysis was performed showing that Ki67 was significantly predictive for pCR in all molecular subgroups. However, in subgroup survival analysis, Ki67 was prognostic in luminal, but not in triple-negative tumors.

Conclusion: Ki67 is a valid predictive and prognostic marker in breast cancer. This marker is significant over a wide range of different cutoffs, which explains the different results of Ki67 cutoffs in different previous studies. Therefore, the variability observed in different studies evaluating Ki67 might reflect A) the wide range of valid cutoffs B) the different clinical endpoints of the studies and C) the different contribution of the molecular subtypes in the study cohorts. Based on our results we suggest three subgroups for Ki67 (0–15% vs. 15.1–35 vs. &gt;35%) as a reasonable approach for further standardization of this marker.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr S4-5.

The 21-gene recurrence score assay impacts adjuvant therapy recommendations for ER-positive, node-negative and node-positive early breast cancer resulting in a risk-adapted change in chemotherapy use

Background

We carried out a prospective clinical study to evaluate the impact of the Recurrence Score (RS) on treatment decisions in early breast cancer (EBC).

Patients and methods

A total of 379 eligible women with estrogen receptor positive (ER+), HER2-negative EBC and 0–3 positive lymph nodes were enrolled. Treatment recommendations, patients' decisional conflict, physicians' confidence before and after knowledge of the RS and actual treatment data were recorded.

Results

Of the 366 assessable patients 244 were node negative (N0) and 122 node positive (N+). Treatment recommendations changed in 33% of all patients (N0 30%, N+ 39%). In 38% of all patients (N0 39%, N+ 37%) with an initial recommendation for chemoendocrine therapy, the post-RS recommendation changed to endocrine therapy, in 25% (N0 22%, N+ 39%) with an initial recommendation for endocrine therapy only to combined chemoendocrine therapy, respectively. A patients' decisional conflict score improved by 6% (P = 0.028) and physicians' confidence increased in 45% (P < 0.001) of all cases. Overall, 33% (N0 29%, N+ 38%) of fewer patients actually received chemotherapy as compared with patients recommended chemotherapy pre-test. Using the test was cost-saving versus current clinical practice.

Conclusion

RS-guided chemotherapy decision-making resulted in a substantial modification of adjuvant chemotherapy usage in node-negative and node-positive ER+ EBC.

Phase IB study of the EpCAM antibody adecatumumab combined with docetaxel in patients with EpCAM-positive relapsed or refractory advanced-stage breast cancer

BACKGROUND

Targeted therapy options in HER2-negative breast cancer are limited. This open-label, multicenter phase IB dose-escalation trial was conducted to determine safety, tolerability, and antitumor activity of a combination of docetaxel (Taxotere) and increasing doses of adecatumumab, a human IgG1 antibody targeting epithelial cell adhesion molecule (EpCAM), in EpCAM-positive relapsed or primary refractory advanced-stage breast cancer.

PATIENTS AND METHODS

Patients pretreated with up to four prior chemotherapy regimens received increasing adecatumumab doses either every 3 weeks (q3w) or weekly (qw) combined with docetaxel (100 mg/m(2) q3w). Primary end points were safety and tolerability. Antitumor activity was evaluated according to RECIST. Clinical benefit was defined as complete or partial response or stable disease for ≥24 weeks.

RESULTS

Thirty-one evaluable patients were treated. Most adverse events were mild to moderate in severity. Neutropenia, leukocytopenia, lymphopenia, and diarrhea (dose-limiting) were the most frequent toxic effects. Maximum tolerated doses of adecatumumab given in combination with docetaxel were 550 mg/m(2) q3w and 360 mg/m(2) qw. Clinical benefit was observed in 44% of patients treated with q3w adecatumumab and docetaxel, increasing to 63% in patients with high EpCAM-expressing tumors.

CONCLUSION

Combination therapy of adecatumumab and docetaxel is safe, feasible, and potentially active in heavily pretreated advanced-stage breast cancer.

Prognostic and predictive impact of Ki-67 before and after neoadjuvant chemotherapy on PCR and survival: Results of the GeparTrio trial

1023

Background: We previously reported as a result of the GeparTrio phase III trial that response-guided neoadjuvant chemotherapy (CT) with TACx8 or TAC/NX, compared to TACx6, can improve survival especially in hormone-receptor (HR)-positive tumors. As this benefit could not be predicted by pathological complete response (pCR), better surrogate response markers are warranted. Methods: 2072 patients with operable or locally advanced breast cancer were treated with 2 cycles TAC before interim response assessment. Responders were randomized to additional TACx4 or TACx6 and non-responders to TACx4 or NXx4. We centrally measured Ki-67 in1165 pre-CT core biopsies and in 676 post-CT surgical samples. Counting patients with a pCR as having 0% Ki-67, 757 pre-/ post-CT pairs were available. Ki-67 percentage levels were grouped to low (0-15%), moderate (15.01-35%), and high (35.01-100%) according to cut-point finding analysis in a training and validation cohort. Results: pCR rates were 4.2%, 12.9%, and 29.0% in tumors with low, moderate, and high pre-CT Ki-67 levels (p<0.0001). Pre-CT Ki-67 levels significantly predicted disease-free survival (DFS) (log rank p<0.0001) overall, in the HR+ (p<0.0001), but not in the HR- (p=0.5) subgroup. Post-CT Ki-67 levels correlated with DFS (p<0.0001). Patients with low post-CT Ki-67 levels showed comparable outcome to patients with pCR. Patients with increased Ki-67 levels from before to after CT showed an impaired outcome compared to patients with stable or decreased Ki-67 levels (p<0.0001). However, post-CT Ki-67 levels appeared to have more prognostic relevance than Ki-67 changes. Low post-CT Ki-67 levels were not more frequent after response-guided treatments (response-guided vs conventional: p=0.153; TACx6 vs TACx8: p=0.335; TACx6 vs TAC/NX: p=0.420). Similar negative results were found for HR+ and HR- subgroups. Conclusions: Pre-CT Ki-67 levels are predictive for pCR and prognostic for DFS. Post-CT Ki-67 levels and changes between pre-and post-CT-Ki-67 levels are prognostic for DFS. As neither could predict different treatment effects on DFS, Ki67 cannot replace pCR as a surrogate marker for outcome after neo-adjuvant CT.

PD07-05: Local Recurrence Risk in 6377 Patients with Early Breast Cancer Receiving Neoadjuvant Anthracycline-Taxane +/− Trastuzumab Containing Chemotherapy

Background: Locoregional recurrence (LRR; defined according to Hudis C, JCO 2007) risk after neoadjuvant systemic treatment is considered as a possible hazard of this treatment approach. However, few data exist on the incidence and risk factors for LRR after anthracycline-taxane+/−trastuzumab (AT+/−H) containing neoadjuvant treatment. We analyzed individual data of 7 prospective neoadjuvant trials conducted by the German Breast Group and the AGO Breast Group.

Patients (Pts) and methods: 6377 Pts with operable or locally advanced, non-metastatic breast cancer were analyzed (for details see von Minckwitz G et al, BCRT 2010). Postsurgical radiotherapy was indicated after breast conservation for all patients and after mastectomy for patients with cT3/4 or cN+ disease. Endocrine treatment was given to ER− and/or PgR-positive patients. 485 LRR were observed during a median follow up of 46.2 (0-127) months.

Results: LRR was similar for patients treated by tumorectomy (7.2% of N=1123), segmentectomy (6.8% of N=1121), quadrantectomy (7% of 557), or breast conservation (BCT) (not otherwise specified) (7.7% of N=819), but higher in patients treated by mastectomy (ME) (12.1% of N=1670) (p&lt;0.001). Rate of breast conservation decreased by increasing initial tumor size (cT1(N=198): 77.7%, cT2(N=3675): 78.1%, cT3(N=795): 49.4%, cT4a-c(N=348): 35.9%, cT4d(N=235):19.1%). LRR in patients treated by BCT or ME were 9.1% vs 9.1% for cT1 (p=0.9); 6.9% vs. 9.8% for cT2 (p=0.001); 9.7% vs 14.2% for cT3 (p=0.04); 3.2% vs. 11.7% for cT4a-c (p=0.004; and 22.2% vs 18.9% for cT4d (p=0.4). LRR increased with surgical yT-stage from 4.7% for ypT0 (N=990), 11.8% for ypTis (N=340), 9.1% for ypT1 (N=1555), 8.2% for ypT2 (N=926), 13.8% for ypT3 (N=232), 20% ypT4a-c (N=80), to 31.2% for ypT4d (N=16) (p&lt;0.001). Comparable results were obtained for cN and ypN stages. Patients with a pathological complete response (pCR = ypT0 ypN0) showed a lower LRR of 3.7% compared to patients not achieving a pCR (3.7% vs 9.9% (HR 0.36 p&lt;0.001). Patients with a pCR showed low LRR in all intrinsic subtypes except Luminal B/HER2+ -like tumors (Luminal A-like tumors (N=105; 3.8%), Luminal B/HER2− -like (N=40; 0%), Luminal B/Her2+ -like (N=124; 8.1%), HER2+(non-luminal)-like (N=158; 1.9%), triple-negative (N=276; 2.5%) (p=0.016). Patients without a pCR showed an excessive LRR for HER2+(non-luminal) and triple-negative tumors (Luminal A-like tumors (N=1498; 5.1%), Luminal B/HER2− -like (N=304; 11.9%), Luminal B/HER2+ -like (N=602; 8.5%), HER2+(non-luminal)-like (N=367; 18%) and triple-negative (N=276; 17.8%) (p&lt;0.001). cT, cN, ypN, intrinsic subtype, but not ypT stage and type of surgery were independent predictors of LRR for patients without pCR in a Cox regression model. None of these factors except Luminal B/HER2+ (p=0.012) were significant in patients with pCR.

Conclusions: LRR in this large pooled analysis after AT+/−H containing neoadjuvant treatment appears to be low, especially in all patients with a pCR except Luminal B/HER2+ disease. In patients without a pCR low cT, cN, ypN and Luminal tumor type predict a low LRR. Other stages and subtypes without pCR should be carefully followed up irrespective of type of surgery.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD07-05.

P4-08-03: Serum Autoantibodies to Breast Cancer Associated Antigens Reflect Tumor Biology: An Opportunity for Early Detection & Prevention?

Autoantibodies (AABs) are produced as an immune response to abnormal ('non-self') cancer antigens. Previous studies have reported that AABs can be measured in the blood long before cancers are presently diagnosed, e.g., up to 4 years before screening mammography identified breast cancers and up to 5 years before screening CT detected lung cancers. EarlyCDT™-Lung is currently available as an aid to early detection of lung cancer in high risk patients and measures a panel of seven AABs to general cancer antigens and also lung cancer (LC) specific antigens. These AABs have previously been reported to be associated with the two main types of LC i.e., non-small cell and small cell LC. This study looked at AABs to 4 general cancer antigens to evaluate whether their levels reflected different biology in primary breast tumors.

Methods

770 patients presented with primary breast cancer to three centers (Nottingham, UK n=323; Munich, Germany n=320; Oklahoma, USA n=127); the median ages and ranges were 61 (26-82), 61 (20-88) & 65 (54-84) years, respectively. All had serum samples taken post-diagnosis and pre-treatment. The tumors were well characterized for histological grade, estrogen receptor (ER), progesterone receptor (PgR) and HER2 status. Serum samples were tested for AABs to four generic cancer antigens(Ags) (p53, SOX2, NY-ESO-1 and Annexin1) originally included as part of Oncimmune's EarlyCDT™-Lung assay. The AABs were measured by ELISA on the Oncimmune platform, and the EarlyCDT™-Lung cutoffs were used to determine positivity.

Results

131/770 (17%) of primary breast cancers showed elevated AAB levels to one or more of the limited panel of four generic antigens. Positivity for each AAB was correlated with histological grade, ER, PgR and HER2 status. The results, which were similar for each of the three centres, were combined, and the results are shown in Table 1 below.

Triple negative breast cancer: proposals for a pragmatic definition and implications for patient management and trial design

In trials in triple negative breast cancer (TNBC), oestrogen and progesterone receptor negativity should be defined as < 1% positive cells. Negativity is a ratio of <2 between Her2 gene copy number and centromere of chromosome 17 or a copy number of 4 or less. In routine practice, immunohistochemistry is acceptable given stringent quality assurance. Triple negativity emerging after neoadjuvant treatment differs from primary TN and such patients should not enter TNBC trials. Patients relapsing with TN metastases should be eligible even if their primary was positive. Rare TN subtypes such as apocrine, adenoid-cystic and low-grade metaplastic tumours should be excluded. TN and basal-like (BL) signatures overlap but are not equivalent. Since the significance of basal cytokeratin or EGFR overexpression is not known and we lack validated assays, these features should not be used to subclassify TN tumours. Tissue collection in trials is mandatory so the effect on outcome of different tumour phenotypes and BRCA mutation can be explored. No prospective studies have established that TN tumours have particular sensitivity or resistance to any specific chemotherapy agent or radiation. TNBC patients should be treated according to tumour and clinical characteristics.

Surgery following neoadjuvant therapy in patients with HER2-positive locally advanced or inflammatory breast cancer participating in the NeOAdjuvant Herceptin (NOAH) study

AIM

To describe surgical outcomes in patients with HER2-positive locally advanced (LABC) or inflammatory breast cancer (IBC) participating in the NeOAdjuvant Herceptin (NOAH) study (ISRCTN86043495).

PATIENTS AND METHODS

A total of 235 patients with HER2-positive disease were randomized to neoadjuvant trastuzumab plus chemotherapy (doxorubicin plus paclitaxel, followed by paclitaxel, followed by cyclophosphamide, methotrexate and fluorouracil) or neoadjuvant chemotherapy alone. Of these patients, 228 received their allocated treatment (115 received trastuzumab plus chemotherapy and 113 received chemotherapy alone) and were potentially eligible for surgery. Mastectomy was required for all patients with IBC and was recommended for all patients with LABC. However, breast-conserving therapy could be considered for patients with peripheral neoplasms measuring ≤ 4 cm in diameter at diagnosis, with a favorable ratio of tumor to breast volume, or at the patient's request if there had been a good response to treatment.

RESULTS

As previously reported, the addition of trastuzumab to neoadjuvant chemotherapy improved the overall, complete and pathological complete response to therapy and significantly improved event-free survival (the primary endpoint of the study). Trastuzumab also enabled more patients to have breast conserving surgery (BCS) (23% versus 13% respectively) without an apparent detrimental effect on local disease control (no patient treated with trastuzumab plus chemotherapy had experienced a local recurrence after BCS at the time of analysis).

CONCLUSIONS

Although this was not an aim of the trial, neoadjuvant trastuzumab given concurrently with chemotherapy enabled 23% of patients with HER2-positive LABC/IBC to avoid mastectomy (including a small number of patients with IBC).

Abstract P3-10-24: Fibroblast Growth Factor Receptor 1 Amplification and Overexpression in Breast Cancer Tissue Microarrays Using Chromogenic In Situ Hybridization and Immunohistochemistry

Fibroblast growth factor receptors 1 (FGFR1) belongs to a subfamily of receptor tyrosine kinases (RTKs), which are involved in proliferation and apoptosis. FGFR1 amplification and mRNA overexpression occurs in ∼10% of breast cancers and has been associated with poor outcome. However, studies assessing FGFR1 amplification and protein overexpression in a large collection of breast tumors are lacking. In this prospective, we examined a series of primary breast cancers samples derived from the BCIRG trials assembled into 15 tissue microarrays. FGFR1 gene amplification was studied using chromogenic in situ hybridization (CISH) and evaluated with respect to association with level of protein expression and clinicopathological parameters. FGFR1 gene amplification was significantly associated with high protein levels as determined by immunohistochemistry (P&lt;0.0001, 3294 pts with available matched CISH and IHC records). Overall, the incidence of FGFR1 amplification found was 9.7% (160 out of 1646 pts. with available clinicopathological records) without a statistically significant difference between Her2- (78 out 720 pts., 11%) and Her2+ (82 out of 926 pts., 9%) cancers. In both cohorts, the hormone receptor-positive (ER+/PR+) cancers showed statistically significant higher levels of FGFR1 amplification compared to hormone receptor-negative tumors. In the analysis of the association of FGFR1 and the presence of PIK3CA mutations, the incidence of FGFR1 amplificationwas greatly reduced in mutant vs. wt PI3KCA tumors. In these cohorts, a clear relationship between FGFR1 amplification status and clinical outcome was not detected. Data from this large study confirms recently reported incidences of FGFR1 amplification in breast cancer and shows for the first time an association between FGFR1 gene amplification and protein overexpression. Moreover, the lower incidence of FGFR1 amplification in PIK3CA mutated cancers suggests that these are largely exclusive molecular events that could benefit from different targeted therapies.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-24.

Abstract PD06-01: A Single Treatment with Targeted Intraoperative Radiotherapy (TARGIT) Is Similar to Several Weeks of External Beam Radiotherapy (EBRT) with Respect to Efficacy and Safety, and Has Obvious Advantages to the Patient and the Economy

Background: After breast-conserving surgery, 90% of local recurrences occur within the index quadrant despite the presence of multicentric cancers elsewhere in the breast. Thus, restriction of radiation therapy to the tumour bed during surgery might be adequate for selected patients. Materials and methods: Having safely piloted the new technique of single-dose targeted intraoperative radiotherapy (TARGIT) with Intrabeam, we launched the TARGIT-A trial on March 24, 2000. In this prospective, randomised, non-inferiority trial, women aged 45 years or older with invasive ductal breast carcinoma undergoing breast-conserving surgery were enrolled to compare TARGIT with whole breast external beam radiotherapy (EBRT). The primary outcome was local recurrence in the conserved breast with a predefined absolute non-inferiority margin of 2-5%. Analysis was by intention-to-treat.

Results: 1113 patients were randomly allocated to TARGIT and 1119 were allocated to EBRT. The Kaplan-Meier estimate of local recurrence in the conserved breast at 4 years was 1-20% (95% CI 0-53-2-71) in the TARGIT and 0-95% (0.39-2-31) in the EBRT group (difference between groups 0.25%, −1.04 to 1.54; p=0.41). The frequency of any complications and major toxicity (TARGIT 3.3% vs. EBRT 3.9% p=0·44) was similar. Radiotherapy toxicity was lower in the TARGIT group (0.5% vs. 2.1%, p=0.002). 14% of patients who received TARGIT also received EBRT as per the protocol, i.e., the remaining 86% patients could safely avoid 3-6 weeks of daily radiotherapy treatments and its obvious associated costs in economic and human terms.

Discussion: For selected patients with early breast cancer, a single-dose targeted intraoperative radiotherapy should be considered as an alternative to whole breast EBRT delivered over several weeks. It could save time, effort, and money for the patient and the healthcare system, which is particularly relevant in the present times of healthcare reform. NB the main trial results have been presented in ASCO 2010 and published in the Lancet Online First.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD06-01.

Safety and efficacy of targeted intraoperative radiotherapy (TARGIT) for early breast cancer: First report of a randomized controlled trial at 10-years maximum follow-up

LBA517

Background: After breast conserving surgery, 90% of local recurrences (LR) occur within the index quadrant. Hence, restricting the radiation therapy to the immediate area around the tumour bed after removal of the primary tumour may be adequate (Vaidya JS, et al. Br Cancer.1996;74:820-4)

Methods: Having safely piloted a new technique of partial breast irradiation (Vaidya JS, Baum M, Tobias JS et al Ann Oncol 2001;12:1075-80) we launched the TARGIT-A trial in March 2000 comparing TARGIT vs. standard whole breast external beam radiotherapy (EBRT) after breast conserving surgery in patients ≥45 years with invasive duct carcinoma. LR was the primary outcome measure (core protocol: www.thelancet.com/protocol-reviews/99PRT-47 ). Trial accrual from 31 international centers is complete (n=2232), with 80% power to detect a difference in relapse rate of 2.5% - the non-inferiority margin.

Results: Median age was 63 (IQR 57-69), median tumor size 13mm (IQR 9-18mm), lymph nodes 17%+ve. Median follow-up is 24.6 months (max 10 years). Wound breakdown or delayed healing were reported in 28 of the TARGIT group and 20 in the EBRT group (p=0.24). RTOG grade 3 toxicity (nil grade 4) was seen in 6 vs. 21 (p=0.004) respectively. Overall local toxicity was equivalent (34/1092 TARGIT v. 41/1096 EBRT, p=0.42). The Kaplan-Meier estimate of LR in the breast, was 0.31% (CI 0.08-1.26) for TARGIT versus 0.29% for EBRT (CI 0.07-1.16) at 24 months.

Conclusions: In the TARGIT group, the radiotherapy toxicity was significantly lower than in the EBRT group, while the increase in wound complications was not statistically significant. This analysis suggests that at a median follow-up of 24 months the local control with TARGIT is comparable to EBRT. Longer term follow-up is essential and accrual in similar studies is encouraged.

[Table: see text]

PI3 Kinase Pathway Analysis in Tissue Microarrays Using Laser Capture Microdissection and Immunohistochemistry

Background. During the performance of the BCIRG trials primary patient tumor samples were obtained from paraffin blocks and assembled into 15 tissue microarrays, including 3000 samples from trial 005 (adjuvant taxol in Her2- node positive patients), 2200 in 006 (adjuvant herceptin in Her2+ high risk patients) and 300 in 007 (addition of platinum in Her2+ first line therapy). This array set was prepared prospectively, in anticipation of molecular epidemiologic studies of a variety of targets in relation to outcome. In order to address the potentially important role of the PIK3CA pathway in modulating outcome in different clinical situations we assessed components of the PIK3CA pathway by various methods.Methods. We analysed the expression of PTEN, Cyclin D1, p53 and Stathmin by immunohistochemistry using standard methods. All markers were scored by histoscore. Phospho S6 240 and phospho Akt 473 were assessed simultaneously by quantum dot immunofluorescence using automated image capture and segmentation. PIK3CA mutations were evaluated using SnaPshot analysis of laser captured TMA spots in a subset of approximately 2000 samples.Results. In the samples analyzed PIK3CA mutation had an incidence of 23%, with 9% being mutations in exon 9 and 13% in exon 20, with 0.5% being mutant in both exons. Initial analysis of the results prior to outcome analysis indicated that Stathmin expression, while being a robust marker with good dynamic range, did not appear to correlate with PTEN loss by IHC or with PIK3CA mutation.Conclusions. PIK3CA mutational analysis is feasible from TMA cores and gives mutation incidences similar to the published literature for archival material. Relationships of markers with outcome will be presented.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4043.

Safety and antitumor activity of 3-weekly anti-EpCAM antibody adecatumumab (MT201) in combination with docetaxel for patients with metastatic breast cancer: Results of a multicenter phase Ib trial

1009

Background: The fully human IgG1 antibody adecatumumab (MT201) binds to the epithelial cell adhesion molecule (EpCAM), which is expressed in over 90% of breast cancers and has been associated with poor prognosis. Data from a previous phase II study in metastatic breast cancer (MBC) indicated that single agent MT201 could prolong progression-free survival in a subset of patients with high EpCAM expression. This study tested safety and tolerability of MT201 treatment in combination with standard docetaxel. Methods: Relapsed or primary refractory, EpCAM-positive MBC patients were treated with docetaxel (100 mg/m2 q21d) in combination with MT201 (dose levels 180 mg/m2, and 550 mg/m2 q21d). A loading dose of 100 mg/m2 and 300 mg/m2, respectively, was administered on day 1 and 7. Patients were grouped into high- and low-level EpCAM expression. Primary objectives were safety and tolerability; anti-tumor activity according to RECIST was a secondary objective. Results: A total of 22 patients with a median of 3 prior chemotherapy lines were enrolled. Most frequent grade 3/4 adverse events (AE) in all patients were leucopenia (90%), neutropenia (77%), lymphopenia (68%), and diarrhea (23%). No evidence for aggravation of grade 3/4 toxicities typically associated with docetaxel was found. The dose level 550 mg/m2 q21d has been determined as MTD in combination with 100 mg/m2 q21d docetaxel. The overall response rate (CR/PR; RECIST) and clinical benefit rate (CR/PR and SD>24wks) in all evaluable patients was 24% and 41%, respectively. Patients with high EpCAM expression showed a response rate of 43%, whereas patients with low EpCAM expression had a response rate of 10%. Median time-to-progression (TTP) in all evaluable patients was 165 days. Conclusions: Combining MT201 with docetaxel for the treatment of MBC appears to be safe and feasible. The DLT of this combination were short and manageable episodes of grade 3 diarrhea. The response rate and TTP observed in this heavily pre-treated population is encouraging and warrant further development of MT201/chemotherapy combinations in patients with tumors of high EpCAM target level.

[Table: see text]