HER2+ Early Breast Cancer: From Escalation via Targeted and Post-Neoadjuvant Treatment to De-Escalation

Background

Human epidermal growth factor receptor 2 positive (HER2+, also referred to as ERBB2+) breast cancer is a subtype, historically associated with a particularly poor prognosis. Research into biological and molecular pathomechanisms of breast cancer has resulted in the development and adoption of several therapies targeting HER2. In parallel, various escalation/de-escalation strategies have been examined to further optimize patient outcomes and care.

Summary

In this review, we highlighted the landmark trials in the evolution of treatment and management of HER2+ early breast cancer (eBC).

Key Messages

Continuous research over the last two decades has gradually prolonged survival in patients with early HER2+ eBC. Incorporation of post-neoadjuvant setting into clinical practice improved long-term outcomes in high-risk patients with residual disease after neoadjuvant therapy. In parallel, use of modern anti-HER2 agents may potentially allow omission of chemotherapy without compromising the survival in a significant number of selected patients. Current research focused on exploring the molecular heterogeneity of HER2+ breast cancer resulted in identification of new prognostic and predictive biomarkers which could pave the way toward the development of truly personalized therapy.

Nab-paclitaxel weekly versus dose-dense solvent-based paclitaxel followed by dose-dense epirubicin plus cyclophosphamide in high-risk HR+/HER2- early breast cancer: results from the neoadjuvant part of the WSG-ADAPT-HR+/HER2- trial

BACKGROUND

In high-risk hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) early breast cancer (EBC), nanoparticle albumin-bound (nab)-paclitaxel showed promising efficacy versus solvent-based (sb)-paclitaxel in neoadjuvant trials; however, optimal patient and therapy selection remains a topic of ongoing research. Here, we investigate the potential of Oncotype DX® recurrence score (RS) and endocrine therapy (ET) response (low post-endocrine Ki67) for therapy selection.

PATIENTS AND METHODS

Within the WSG-ADAPT trial (NCT01779206), high-risk HR+/HER2- EBC patients were randomized to (neo)adjuvant 4× sb-paclitaxel 175 mg/m2 q2w or 8× nab-paclitaxel 125 mg/m2 q1w, followed by 4× epirubicin + cyclophosphamide (90 mg + 600 mg) q2w; inclusion criteria: (i) cN0-1, RS 12-25, and post-ET Ki67 >10%; (ii) cN0-1 with RS >25. Patients with cN2-3 or (G3, baseline Ki67 ≥40%, and tumor size >1 cm) were allowed to be included without RS and/or ET response testing. Associations of key factors with pathological complete response (pCR) (primary) and survival (secondary) endpoints were analyzed using statistical mediation and moderation models.

RESULTS

Eight hundred and sixty-four patients received neoadjuvant nab-paclitaxel (n= 437) or sb-paclitaxel (n = 427); nab-paclitaxel was superior for pCR (20.8% versus 12.9%, P = 0.002). pCR was higher for RS >25 versus RS ≤25 (16.0% versus 8.4%, P = 0.021) and for ET non-response versus ET response (15.1% versus 6.0%, P = 0.027); no factors were predictive for the relative efficacy of nab-paclitaxel versus sb-paclitaxel. Patients with pCR had longer distant disease-free survival [dDFS; hazard ratio 0.42, 95% confidence interval (CI) 0.20-0.91, P = 0.024]. Despite favorable prognostic association of RS >25 versus RS ≤25 with pCR (odds ratio 3.11, 95% CI 1.71-5.63, P ≤ 0.001), higher RS was unfavorably associated with dDFS (hazard ratio 1.03, 95% CI 1.01-1.05, P = 0.010).

CONCLUSIONS

In high-risk HR+/HER2- EBC, neoadjuvant nab-paclitaxel q1w appears superior to sb-paclitaxel q2w regarding pCR. Combining RS and ET response assessment appears to select patients with highest pCR rates. The disadvantage of higher RS for dDFS is reduced in patients with pCR. These are the first results from a large neoadjuvant randomized trial supporting the use of RS to help select patients for neoadjuvant chemotherapy in high-risk HR+/HER2- EBC.

Efficacy of Endocrine Therapy Plus Trastuzumab and Pertuzumab vs De-escalated Chemotherapy in Patients with Hormone Receptor-Positive/ERBB2-Positive Early Breast Cancer: The Neoadjuvant WSG-TP-II Randomized Clinical Trial

Importance

Combination of chemotherapy with (dual) ERBB2 blockade is considered standard in hormone receptor (HR)-positive/ERBB2-positive early breast cancer (EBC). Despite some promising data on endocrine therapy (ET) combination with dual ERBB2 blockade in HR-positive/ERBB2-positive BC, to our knowledge, no prospective comparison of neoadjuvant chemotherapy vs ET plus ERBB2 blockade in particular with focus on molecular markers has yet been performed.

Objective

To determine whether neoadjuvant de-escalated chemotherapy is superior to endocrine therapy, both in combination with pertuzumab and trastuzumab, in a highly heterogeneous HR-positive/ERBB2-positive EBC.

Design, Setting, and Participants

This prospective, multicenter, neoadjuvant randomized clinical trial allocated 207 patients with centrally confirmed estrogen receptor-positive and/or progesterone receptor-positive (>1%) HR-positive/ERBB2-positive EBC to 12 weeks of standard ET (n = 100) vs paclitaxel (n = 107) plus trastuzumab and pertuzumab. A total of 186 patients were required to detect a statistically significant difference in pathological complete response (pCR) (assumptions: 19% absolute difference in pCR; power, ≥80%; 1-sided Fisher exact test, 2.5% significance level).

Interventions

Standard ET (aromatase inhibitor or tamoxifen) or paclitaxel, 80 mg/m2, weekly plus trastuzumab and pertuzumab every 21 days.

Main Outcomes and Measures

The primary end point was pCR (ypT0/is, ypN0). Secondary end points included safety, translational research, and health-related quality of life. Omission of further chemotherapy was allowed in patients with pCR. PAM50 analysis was performed on baseline tumor biopsies.

Results

Of the 207 patients included (median [range] age, 53 [25-83] years), 121 (58%) had cT2 to cT4 tumors, and 58 (28%) had clinically node-positive EBC. The pCR rate in the ET plus trastuzumab and pertuzumab arm was 23.7% (95% CI, 15.7%-33.4%) vs 56.4% (95% CI, 46.2%-66.3%) in the paclitaxel plus trastuzumab and pertuzumab arm (odds ratio, 0.24; 95% CI, 0.12-0.46; P < .001). Both immunohistochemical ERBB2 score of 3 or higher and ERBB2-enriched subtype were independent predictors for pCR in both arms. Paclitaxel was superior to ET only in the first through third quartiles but not in the highest ERBB2 quartile by messenger RNA. In contrast with the paclitaxel plus trastuzumab and pertuzumab arm, no decrease in health-related quality of life after 12 weeks was observed in the ET plus trastuzumab and pertuzumab arm.

Conclusions and Relevance

The WSG-TP-II randomized clinical trial is, to our knowledge, the first prospective trial comparing 2 neoadjuvant de-escalation treatments in HR-positive/ERBB2-positive EBC and demonstrated an excellent pCR rate after 12 weeks of paclitaxel plus trastuzumab and pertuzumab that was clearly superior to the pCR rate after ET plus trastuzumab and pertuzumab.

Trial Registration

ClinicalTrials.gov Identifier: NCT03272477.

Molecular Profiling in Early ER + Breast Cancer to Aid Systemic Therapy Decisions

PURPOSE OF REVIEW

Clinical decisions for (neo)adjuvant treatment in early breast cancer (eBC) have been based mostly on clinical factors over the last decades. We have reviewed development and validation of such assays in the HR + /HER2 eBC and discuss possible future directions in this field.

RECENT FINDINGS

Increasing knowledge about the biology of hormone-sensitive eBC, based on the precise and reproducible multigene expression analysis, has led to a significant change in the treatment pathways and reduction of overtreatment in particular by chemotherapy in HR + /HER2 eBC with up to 3 positive lymph nodes based on results from several retrospective-prospective trials used several genomic assays and in particular prospective trials (TAILORx, RxPonder, MINDACT, and ADAPT used OncotypeDX® and Mammaprint®). Precise evaluation of tumor biology together with endocrine responsiveness assessment appears as promising tools for individualized treatment decisions together with clinical factors and menopausal status in early hormone-sensitive/HER2-negative breast cancer.

Abstract P5-02-03: Combined biomarker analysis for prediction of pathological complete response (pCR) after 12 weeks of pembrolizumab + trastuzumab + pertuzumab in HER2-enriched early breast cancer: Keyriched-1 trial

Background In unselected HER2+ early breast cancer (EBC), de-escalated chemotherapy-free neoadjuvant therapy (NAT) with dual HER2-blockade induces pCR rates of only 20%-40%. In order to achieve pCR rates by de-escalated therapy comparable to those achieved by chemotherapy-based regimens, patient selection and more effective chemotherapy-free regimens are thus key. KEYRICHED-1 (NCT03988036), a single-arm phase 2 study, is the first trial to investigate chemotherapy-free NAT with dual HER2 blockade and pembrolizumab in HER2-enriched HER2+ EBC. In a translational subproject, we analyzed gene signatures together with tumor cell proliferation and spatiotemporal immune cell profiling to identify predictive factors for pCR. Methods 48 pre- and postmenopausal patients with newly diagnosed HER2 2+ (ISH positive) or 3+ EBC (stage I-III) and HER2-enriched (HER2-E) subtype by PAM50 were included in the study. All patients received 4 cycles of pembrolizumab (200 mg), trastuzumab biosimilar ABP 980 (loading dose (LD) 8 mg/kg bodyweight (BW), maintenance dose (MD) 6 mg/kg BW), and pertuzumab (LD 840 mg/kg BW, MD 420 mg/kg BW) q21d. Primary objective was pCR (centrally confirmed absence of invasive tumor in breast and lymph nodes: ypT0/is, ypN0). NanoString Breast Cancer 360 panel was performed in baseline biopsies (n=42). ≥30% Ki67 decrease, &lt; 500 invasive tumor cells or no evidence of tumor in week 3 biopsies (on treatment) were classified as early response. sTILs were analyzed at baseline (n=42) and week 3 (n=28). Ongoing analyses include whole exome sequencing and multiplexed immunohistochemistry for expression of PD1, PDL1, CD4, CD8, CD68, and CD20 levels in tumor and stroma at baseline and at week 3. Impact of standardized expression of single genes, signatures, and sTILs on pCR was evaluated with univariable and multivariate logistic regression analyses and summarized with odds ratios (OR) and 95% confidence intervals (95%CI). Results 42 patients with BC360 and sTILs data at baseline were included in the analysis. Median age was 55 years (range: 22-83), 11 patients (31%) had node-positive EBC. At baseline, 28 patients had sTIL levels ≥30% and 14 had sTILs &lt; 30%; the corresponding pCR rates were 57.1% (n=16) and 28.6% (n=4, p=0.108). At week 3 (on treatment), 16 patients had sTIL levels ≥30%, 50% (n=8) had a pCR vs 8.3% in those with &lt; 30% sTILs (one patient out of 12, p=0.039). 37 patients had early response, 54.1% of them (n=20) had a pCR vs 0% in early non-responders (n=5, p=0.049). In univariate analysis, IDO1, ERBB2, IFNγ, cytotoxic cells, cytotoxicity, CD8 T-cells, TIGIT, and tumor inflammation signatures were statistically significantly associated with pCR (OR 2.3-3.6); ERBB2, IDO1, IFNγ and CD8 T-cells remained significant after adjusting for hormone receptor (HR) and central HER2 status (OR 2.2-4.3). 70 single genes were predictive for pCR; none of them remained significant after false discovery rate adjustment (25%). In multivariable analysis for baseline markers including signatures, sTILs, HR and central HER2 status, only ERBB2 (OR 8.7, 95%CI 1.9-39.0, p=0.0046) and cytotoxic cells signatures (OR 4.6, 95%CI 1.6-13.5, p=0.0059) were predictive for pCR. Results of whole exome sequencing, and multiplexed immunohistochemistry analysis of immune cell markers will be presented at the Symposium. Conclusions Biomarker analysis in the unique KEYRICHED-1 cohort revealed that early response at week 3, ERBB2 and immune related signatures as well as on-therapy sTIL levels predict pCR after a chemotherapy-free combination of immunotherapy and dual HER2 blockade in HER2-enriched EBC. These results pave the way for validation in larger de-escalation trials investigating short, chemotherapy-free regimens in selected patients with HER2+ EBC. Funding for this research was provided by MSD Sharp & Dohme GmbH.

Citation Format: Monika Graeser, Sherko Kuemmel, Oleg Gluz, Friedrich Feuerhake, Valery Volk, Daniel Ulbrich-Gebauer, Claudia Biehl, Mattea Reinisch, Athina Kostara9, Iris Scheffen, Kerstin Luedtke-Heckenkamp, Andreas Hartkopf, Felix Hilpert, Angela Kentsch, Carsten Ziske, Reinhard Depenbusch, Michael Braun, Jens-Uwe Blohmer, Christine zu Eulenburg, Matthias Christgen, Ronald Kates, Stephan Bartels, Hans-Heinrich Kreipe, Enrico Pelz, Peter Schmid, Nadia Harbeck. Combined biomarker analysis for prediction of pathological complete response (pCR) after 12 weeks of pembrolizumab + trastuzumab + pertuzumab in HER2-enriched early breast cancer: Keyriched-1 trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-02-03.

De-Escalated Neoadjuvant Trastuzumab-Emtansine With or Without Endocrine Therapy Versus Trastuzumab With Endocrine Therapy in HR+/HER2+ Early Breast Cancer: 5-Year Survival in the WSG-ADAPT-TP Trial

PURPOSE

Neoadjuvant chemotherapy is standard of care in human epidermal growth factor receptor 2-positive (HER2+) early breast cancer (EBC), irrespective of the hormone receptor status. Trastuzumab-emtansine (T-DM1), antibody-drug conjugate, is highly effective in HER2+ EBC; however, no survival data are available for de-escalated antibody-drug conjugate-based neoadjuvant therapy without conventional chemotherapy.

PATIENTS AND METHODS

In the WSG-ADAPT-TP (ClinicalTrials.gov identifier: NCT01779206) phase II trial, 375 centrally reviewed patients with hormone receptor-positive (HR+)/HER2+ EBC (clinical stage I-III) were randomly assigned to 12 weeks of T-DM1 with or without endocrine therapy (ET) or trastuzumab + ET once every 3 weeks (ratio 1:1:1). Adjuvant chemotherapy (ACT) omission was allowed in patients with pathologic complete response (pCR). In this study, we report the secondary survival end points and biomarker analysis. Patients who received at least one dose of study treatment were analyzed. Survival was analyzed using the Kaplan-Meier method, two-sided log-rank statistics, and Cox regression models stratified for nodal and menopausal status. P values < .05 were considered statistically significant.

RESULTS

T-DM1, T-DM1 + ET, and trastuzumab + ET induced similar 5-year invasive disease-free survival (iDFS; 88.9%, 85.3%, 84.6%; P_log-rank = .608) and overall survival rates (97.2%, 96.4%, 96.3%; P_log-rank = .534). Patients with pCR versus non-pCR had improved 5-year iDFS rates (92.7% v 82.7%; hazard ratio, 0.40; 95% CI, 0.18 to 0.85). Among the 117 patients with pCR, 41 did not receive ACT; 5-year iDFS rates were similar in those with (93.0%; 95% CI, 84.0 to 97.0) and without ACT (92.1%; 95% CI, 77.5 to 97.4; P_log-rank = .848). Translational research revealed that tumors with PIK3CA wild type, high immune marker expression, and luminal-A tumors (by PAM50) had an excellent prognosis with de-escalated anti-HER2 therapy.

CONCLUSION

The WSG-ADAPT-TP trial demonstrated that pCR after 12 weeks of chemotherapy-free de-escalated neoadjuvant therapy was associated with excellent survival in HR+/HER2+ EBC without further ACT. Despite higher pCR rates for T-DM1 ± ET versus trastuzumab + ET, all trial arms had similar outcomes because of mandatory standard chemotherapy after non-pCR. WSG-ADAPT-TP demonstrated that such de-escalation trials in HER2+ EBC are feasible and safe for patients. Patient selection on the basis of biomarkers or molecular subtypes may increase the efficacy of systemic chemotherapy-free HER2-targeted approaches.

Impact of RNA Signatures on pCR and Survival after 12-Week Neoadjuvant Pertuzumab plus Trastuzumab with or without Paclitaxel in the WSG-ADAPT HER2+/HR- Trial

PURPOSE

To identify associations of biological signatures and stromal tumor-infiltrating lymphocytes (sTIL) with pathological complete response (pCR; ypT0 ypN0) and survival in the Phase II WSG-ADAPT HER2+/HR- trial (NCT01817452).

EXPERIMENTAL DESIGN

Patients with cT1-cT4c, cN0-3 HER2+/HR- early breast cancer (EBC) were randomized to pertuzumab+trastuzumab (P+T, n = 92) or P+T+paclitaxel (n = 42). Gene expression signatures were analyzed in baseline biopsies using NanoString Breast Cancer 360 panel (n = 117); baseline and on-treatment (week 3) sTIL levels were available in 119 and 76 patients, respectively. Impacts of standardized gene expression signatures on pCR and invasive disease-free survival (iDFS) were estimated by logistic and Cox regression.

RESULTS

In all patients, ERBB2 [OR, 1.70; 95% confidence interval (CI), 1.08-2.67] and estrogen receptor (ER) signaling (OR, 1.72; 95% CI, 1.13-2.61) were favorable, whereas PTEN (OR, 0.57; 95% CI, 0.38-0.87) was unfavorable for pCR. After 60 months median follow-up, 13 invasive events occurred (P+T: n = 11, P+T+paclitaxel: n = 2), none following pCR. Gene signatures related to immune response (IR) and ER signaling were favorable for iDFS, all with similar HR about 0.43-0.55. These patterns were even more prominent in the neoadjuvant chemotherapy-free group, where additionally BRCAness signature was unfavorable (HR, 2.00; 95% CI, 1.04-3.84). IR signatures were strongly intercorrelated. sTILs (baseline/week 3/change) were not associated with pCR or iDFS, though baseline sTILs correlated positively with IR signatures.

CONCLUSIONS

Distinct gene signatures were associated with pCR versus iDFS in HER2+/HR- EBC. The potential role of IR in preventing recurrence suggests that patients with upregulated IR signatures could be candidates for de-escalation concepts in HER2+ EBC.

p53 Expression in Luminal Breast Cancer Correlates With TP53 Mutation and Primary Endocrine Resistance

TP53 mutation is associated with primary endocrine resistance in luminal breast cancer (BC). Nuclear accumulation of p53, as determined by immunohistochemistry (IHC), is a surrogate marker for TP53 mutation. The immunohistochemical p53 index that defines a p53-positive status is not well established. This study determined the optimal p53 index cutoff to identify luminal BCs harboring TP53 mutations. In total, 364 luminal BCs from the West German Study Group ADAPT trial (NCT01779206) were analyzed for TP53 mutations by next-generation sequencing and for p53 expression by IHC (DO-7 antibody). P53 indices were determined by automated image analysis. All tumors were from patients treated with short-term preoperative endocrine therapy (pET; tamoxifen or aromatase inhibitor) before tumor resection. IHC evaluation included needle biopsies before therapy (baseline) and resections specimens after therapy (post-pET). Optimal p53 index cutoffs were defined with Youden statistics. TP53 mutations were detected in 16.3% of BC cases. The median p53 indices were significantly higher in TP53-mutated BCs compared to BCs harboring wild-type TP53 (baseline: 47.0% vs 6.4%, P < .001; post-pET: 50.1% vs 1.1%, P < .001). Short-term pET decreased p53 indices in BCs harboring wild-type TP53 (P < .001) but not in TP53-mutated BCs (P = .102). For baseline biopsies, the optimal p53 index cutoff was ≥34.6% (specificity 0.92, sensitivity 0.63, Youden index 0.54, accuracy: 0.87). For post-pET specimens, the optimal cutoff was ≥25.3% (specificity 0.95, sensitivity 0.65, Youden index 0.60, accuracy: 0.90). Using these cutoffs to define the p53 status, p53-positive BCs were >2-fold more common in pET nonresponders compared to pET responders (baseline: 37/162, 22.8% vs 18/162, 11.1%, P = .007; post-pET: 36/179, 20.1% vs 16/179, 8.9%, P = .004). In summary, IHC for p53 identifies TP53-mutated luminal BCs with high specificity and accuracy. Optimal cutoffs are ≥35% and ≥25% for treatment-naïve and endocrine-pretreated patients, respectively.

De-escalated Neoadjuvant Chemotherapy in Early Triple-Negative Breast Cancer (TNBC): Impact of Molecular Markers and Final Survival Analysis of the WSG-ADAPT-TN Trial

PURPOSE

Although optimal treatment in early triple-negative breast cancer (TNBC) remains unclear, de-escalated chemotherapy appears to be an option in selected patients within this aggressive subtype. Previous studies have identified several pro-immune factors as prognostic markers in TNBC, but their predictive impact regarding different chemotherapy strategies is still controversial.

EXPERIMENTAL DESIGN

ADAPT-TN is a randomized neoadjuvant multicenter phase II trial in early patients with TNBC (n = 336) who were randomized to 12 weeks of nab-paclitaxel 125 mg/m2 + gemcitabine or carboplatin d 1,8 q3w. Omission of further (neo-) adjuvant chemotherapy was allowed only in patients with pathological complete response [pCR, primary endpoint (ypT0/is, ypN0)]. Secondary invasive/distant disease-free and overall survival (i/dDFS, OS) and translational research objectives included quantification of a predictive impact of markers regarding selection for chemotherapy de-escalation, measured by gene expression of 119 genes (including PAM50 subtype) by nCounter platform and stromal tumor-infiltrating lymphocytes (sTIL).

RESULTS

After 60 months of median follow-up, 12-week-pCR was favorably associated (HR, 0.24; P = 0.001) with 5y-iDFS of 90.6% versus 62.8%. No survival advantage of carboplatin use was observed, despite a higher pCR rate [HR, 1.04; 95% confidence interval (CI), 0.68-1.59]. Additional anthracycline-containing chemotherapy was not associated with a significant iDFS advantage in pCR patients (HR, 1.29; 95% CI, 0.41-4.02). Beyond pCR rate, nodal status and high sTILs were independently associated with better iDFS, dDFS, and OS by multivariable analysis.

CONCLUSIONS

Short de-escalated neoadjuvant taxane/platinum-based combination therapy appears to be a promising strategy in early TNBC for using pCR rate as an early decision point for further therapy (de-) escalation together with node-negative status and high sTILs. See related commentary by Sharma, p. 4840.

Impact of stromal tumor-infiltrating lymphocytes (sTILs) on response to neoadjuvant chemotherapy in triple-negative early breast cancer in the WSG-ADAPT TN trial

BACKGROUND

Higher density of stromal tumor-infiltrating lymphocytes (sTILs) at baseline has been associated with increased rates of pathological complete response (pCR) after neoadjuvant chemotherapy (NACT) in triple-negative breast cancer (TNBC). While evidence supports favorable association of pCR with survival in TNBC, an independent impact of sTILs (after adjustment for pCR) on survival is not yet established. Moreover, the impact of sTIL dynamics during NACT on pCR and survival in TNBC is unknown.

METHODS

The randomized WSG-ADAPT TN phase II trial compared efficacy of 12-week nab-paclitaxel with gemcitabine versus carboplatin. This preplanned translational analysis assessed impacts of sTIL measurements at baseline (sTIL-0) and after 3 weeks of chemotherapy (sTIL-3) on pCR and invasive disease-free survival (iDFS). Predictive performance of sTIL-0 and sTIL-3 for pCR was quantified by ROC analysis and logistic regression; Kaplan-Meier estimation and Cox regression (with mediation analysis) were used to determine their impact on iDFS.

RESULTS

For prediction of pCR, the AUC statistics for sTIL-0 and sTIL-3 were 0.60 and 0.63, respectively, in all patients; AUC for sTIL-3 was higher in NP/G. The positive predictive value (PPV) of "lymphocyte-predominant" status (sTIL-0 ≥ 60%) at baseline was 59.3%, though only 13.0% of patients had this status. To predict non-pCR, the cut point sTIL-0 ≤ 10% yielded PPV = 69.5% while addressing 33.8% of patients. Higher sTIL levels (particularly at 3 weeks) were independently and favorably associated with better iDFS, even after adjusting for pCR. For example, the adjusted hazard ratio for 3-week sTILs ≥ 60% (vs. < 60%) was 0.48 [0.23-0.99]. Low cellularity in 3-week biopsies was the strongest individual predictor for pCR (in both therapy arms), but not for iDFS.

CONCLUSION

The independent impact of sTILs on iDFS suggests that favorable immune response can influence key tumor biological processes for long-term survival. The results suggest that the reliability of pCR following neoadjuvant therapy as a surrogate for survival could vary among subgroups in TNBC defined by immune response or other factors. Dynamic measurements of sTILs under NACT could support immune response-guided patient selection for individualized therapy approaches for both very low levels (more effective therapies) and very high levels (de-escalation concepts).

TRIAL REGISTRATION

Clinical trials No: NCT01815242, retrospectively registered January 25, 2013.

Adjuvant dynamic marker-adjusted personalized therapy comparing endocrine therapy plus ribociclib versus chemotherapy in intermediate-risk HR+/HER2- early breast cancer: ADAPTcycle

TPS609

Background: The WSG ADAPT trial program focusses on individualization of (neo)-adjuvant decision-making in EBC in a subtype-specific manner. Clinical feasibility of the WSG ADAPT trial goals - early response assessment and subtype-specific therapy tailoring to those patients (pts) who are most likely to benefit - has recently been confirmed by the 5-years survival data of the ADAPT HR+/HER2- clinical trial. Methods: WSG-ADAPTcycle is a prospective, multi-center, interventional, two-arm, (neo)adjuvant, non-blinded, randomized, controlled phase III trial (NCT04055493) investigating whether treatment with the CDK4/6 inhibitor ribociclib (600mg/day) together with ET is superior to standard-chemotherapy (CT) in intermediate-risk HR+/HER2- EBC. Definition of intermediate-risk is either based on Oncotype DX and endocrine responder status (measured by Ki67-response after 2-4 weeks of induction endocrine therapy (ET)) or on low-intermediate baseline Ki67 and high estrogen receptor (ER)/progesterone receptor (PR)-expression (Dowsett et al. NPJ Breast Cancer 2020). Co-primary endpoints are DFS and dDFS. It is planned to screen 5600 pts and to randomize 1670 pts (1002 to ribociclib + ET; 668 to standard CT followed by ET). Study start was in July 2019 (88 sites, enrollment period 42 months) and until date of submission, 3079 pts have been screened and 811 randomized (490 ribociclib / 321 CT). Pre-/postmenopausal pts with histologically confirmed invasive HR+/HER2- EBC with high clinical risk (cT2-4 or Ki-67 20% or G3 or cN+) are eligible if they fulfil the ADAPT intermediate-risk criteria: Recurrence Score (RS) ≤25 plus several risk factors and poor ET responder, RS >25 and ET-responder in p/cN0-1 pts, or RS ≤25 with c/pN2-3 in ET-responder. Direct randomization of premenopausal patients (irrespective of ET-response) with c/pN0 and RS 16-25 or c/pN1 with RS 0-25 is allowed according to investigator´s decision; however, based on the ADAPT results, ET+ovarian function suppression alone is strongly recommended in ET-responders. Treatment duration is 2 years for the ribociclib + aromatase inhibitor (AI) (premenopausal: AI + GnRH)-arm and 16-24 weeks for the CT-arm; neoadjuvant or adjuvant treatment is allowed. The minimum 5-year follow-up phase includes standard adjuvant ET. ePROs are collected using CANKADO; ECG monitoring is performed using a novel eHealth method. Translational analyses: Tumor tissue will be collected prior to ET, after at least 3 weeks of ET, if residual tumor is diagnosed (neoadjuvant treatment), and at recurrence, to identify potential resistance markers. Exploratory tissue biomarker research will be conducted to assess alterations in molecular markers. In addition, ctDNA/ctRNA from optional blood samples will be assessed for mutations and gene expression relevant for HR+/HER2- EBC. Clinical trial information: NCT04055493.

Inter-observer agreement for the histological diagnosis of invasive lobular breast carcinoma

Invasive lobular breast carcinoma (ILC) is the second most common breast carcinoma (BC) subtype and is mainly driven by loss of E‐cadherin expression. Correct classification of BC as ILC is important for patient treatment. This study assessed the degree of agreement among pathologists for the diagnosis of ILC. Two sets of hormone receptor (HR)‐positive/HER2‐negative BCs were independently reviewed by participating pathologists. In set A (61 cases), participants were provided with hematoxylin/eosin (HE)‐stained sections. In set B (62 cases), participants were provided with HE‐stained sections and E‐cadherin immunohistochemistry (IHC). Tumor characteristics were balanced. Participants classified specimens as non‐lobular BC versus mixed BC versus ILC. Pairwise inter‐observer agreement and agreement with a pre‐defined reference diagnosis were determined with Cohen's kappa statistics. Subtype calls were correlated with molecular features, including CDH1/E‐cadherin mutation status. Thirty‐five pathologists completed both sets, providing 4,305 subtype calls. Pairwise inter‐observer agreement was moderate in set A (median κ = 0.58, interquartile range [IQR]: 0.48–0.66) and substantial in set B (median κ = 0.75, IQR: 0.56–0.86, p < 0.001). Agreement with the reference diagnosis was substantial in set A (median κ = 0.67, IQR: 0.57–0.75) and almost perfect in set B (median κ = 0.86, IQR: 0.73–0.93, p < 0.001). The median frequency of CDH1/E‐cadherin mutations in specimens classified as ILC was 65% in set A (IQR: 56–72%) and 73% in set B (IQR: 65–75%, p < 0.001). Cases with variable subtype calls included E‐cadherin‐positive ILCs harboring CDH1 missense mutations, and E‐cadherin‐negative ILCs with tubular elements and focal P‐cadherin expression. ILCs with trabecular growth pattern were often misclassified as non‐lobular BC in set A but not in set B. In conclusion, subtyping of BC as ILC achieves almost perfect agreement with a pre‐defined reference standard, if assessment is supported by E‐cadherin IHC. CDH1 missense mutations associated with preserved E‐cadherin protein expression, E‐ to P‐cadherin switching in ILC with tubular elements, and trabecular ILC were identified as potential sources of discordant classification.

Abstract PD10-11: Keyriched-1- A prospective, multicenter, open label, neoadjuvant phase ii single arm study with pembrolizumab in combination with dual anti-HER2 blockade with trastuzumab and pertuzumab in early breast cancer patients with molecular HER2-enriched intrinsic subtype

Background: De-escalating strategies seem promising in HER2-positive early breast cancer (EBC) and chemo-free regimens are thus of key interest. Recent data have underlined the role of tumor immunogenicity in response to de-escalated neoadjuvant anti-HER2 therapy. Therefore, the prospective single arm hypothesis-generating phase II KEYRICHED-1 trial (NCT03988036) investigates the pCR-rate in patients with HER2-enriched EBC receiving four cycles of the dual anti-HER2 blockade in combination with the checkpoint inhibitor pembrolizumab. Initial studies with dual antibody-based HER2 blockade alone were able to achieve pCR-rates of 20-40%, which did not quite match the pCR-rates obtained with concurrent chemotherapy. KEYRICHED-1 aims at achieving pCR-rates comparable to standard chemotherapy-containing regimens by incorporating appropriate molecular selection and immune oncology.. Methods: A total of 48 pre- and postmenopausal patients with newly diagnosed HER2 2+ or 3+ EBC (stage I-III) and HER2-enriched (HER2-E) subtype by PAM50 were enrolled in this single-arm study. All patients received four cycles of study treatment with pembrolizumab (200mg), trastuzumab biosimilar (Trazimera®, loading dose 8mg/kg bodyweight (BW), maintenance dose 6mg/kg BW), and pertuzumab (loading dose 840mg/kg BW, maintenance dose 420mg/kg BW) q21d. Primary endpoint was centrally confirmed pCR (ypT0/is, ypN0). The trial was planned as a Simon's two-stage design (null and alternative pCR were 40% and 60%); interim analysis after 16 patients had to show a pCR rate of at least 50% to continue recruitment.. Results: Between 05/2020 and 03/2021, 98 patients were screened. N=52 (55%) had HER2-E subtype, of whom 48 patients entered the treatment phase. Median patient age was 57 years (28-83). 65% had tumors &gt; 2 cm and 30% positive lymph node status. Centrally confirmed pCR-rate in surgical specimens was 46% (95% CI 0.31-0.62) in the 43 patients of the per-protocol-population, and 52% (95%CI 0.37-0.67) in all 46 evaluable patients (local assessment; two pCRs verified only by core biopsy) (p=0.22 and p=0.06 for null hypothesis, respectively). Despite HER2-E subtype, no pCR was observed in the four patients with immunohistochemical (IHC) HER2 2+/ISH-positive status in contrast to 20/39 (51.2%) pCR in IHC HER2 3+ tumors. Centrally confirmed pCR-rate in HR+/HER2+ tumors was 38.5% compared to 58.5% in HR-/HER2+ tumors. No new safety signals were observed.. Conclusions: These are the first results of a neoadjuvant chemotherapy-free 12-week de-escalation anti-HER2-regimen with trastuzumab and pertuzumab in combination with the PD-1 inhibitor pembrolizumab in patients with a HER2-E EBC. In the context of the WSG ADAPT HER2+ de-escalation trials the observed pCR-rates compare favorably in HR+ as well as HR- HER2+ EBC. Moreover, KEYRICHED-1 demonstrates that with appropriate molecular patient selection clinically meaningful pCR-rates in the range of those obtained with longer, more toxic chemotherapy-containing regimens can be achieved.

Citation Format: Sherko Kuemmel, Oleg Gluz, Mattea Reinisch, Athina Kostara, Iris Scheffen, Monika Graeser, Rachel Wuerstlein, Ulrike Nitz, Kerstin Luedtke-Heckenkamp, Andreas Hartkopf, Felix Hilpert, Angela Kentsch, Carsten Ziske, Reinhard Depenbusch, Michael Braun, Jens Blohmer, Christine zu Eulenburg, Matthias Christgen, Stephan Bartels, Hans Kreipe, Enrico Pelz, Peter Schmid, Nadia Harbeck. Keyriched-1- A prospective, multicenter, open label, neoadjuvant phase ii single arm study with pembrolizumab in combination with dual anti-HER2 blockade with trastuzumab and pertuzumab in early breast cancer patients with molecular HER2-enriched intrinsic subtype [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD10-11.

Abstract P2-13-03: KEYRICHED-1 - A prospective, multicenter, open label, neoadjuvant phase II single arm study with pembrolizumab in combination with dual anti-HER2 blockade with trastuzumab and pertuzumab in early breast cancer patients with molecular HER2-enriched intrinsic subtype

Background: De-escalating strategies seem promising inHER2-positive early breast cancer (EBC) and chemo-free regimens are thus of keyinterest. Recent data have underlined the role of tumor immunogenicity inresponse to de-escalated neoadjuvant anti-HER2 therapy. Therefore, theprospective single arm hypothesis-generating phase II KEYRICHED-1 trial (NCT03988036)investigates the pCR rate in patients with HER2-enriched EBC receiving fourcycles of the dual anti-HER2 blockade in combination with the checkpointinhibitor pembrolizumab. Initial studies with dual antibody-based HER2 blockadealone were able to achieve pCR-rates of 20-40%, which did not quite match the pCRrates obtained with concurrent chemotherapy. KEYRICHED-1 aims at achieving pCR-ratescomparable to standard chemotherapy-containing regimens by incorporating appropriatemolecular selection and immune oncology. Methods: A total of 48 pre- and postmenopausal patients with newly diagnosed HER22+ or 3+ EBC (stage I-III) and HER2-enriched (HER2-E) subtype by PAM50 wereenrolled in this single-arm study. All patients received four cycles of studytreatment with pembrolizumab (200mg), trastuzumab biosimilar (Trazimera®,loading dose 8mg/kg bodyweight (BW), maintenance dose 6mg/kg BW), and pertuzumab(loading dose 840mg/kg BW, maintenance dose 420mg/kg BW) q21d . Primaryendpoint was centrally confirmed pCR (ypT0/is, ypN0). The trial was planned asa Simon's two-Stage design (null and alternative pCR were 40% and 60%); interimanalysis after 16 patients had to show a pCR rate of at least 50% to continuerecruitment. Results: Between 05/2020 and 03/2021, 98 patients werescreened. N=52 (55%) had HER2-E subtype,of whom 48 patients entered thetreatment phase. Median patient age was 57 years (28-83). 65% had tumors &gt; 2cm and 30% positive lymph node status. Centrally confirmed pCR rate in surgicalspecimens was 46% (95% CI 0.31-0.62) in the 43 patients of the per protocolpopulation, and 52% (95%CI 0.37-0.67) in all 46 evaluable patients (localassessment; two pCRs verified only by core biopsy) (p=0.22 and p=0.06 for nullhypothesis, respectively). Despite HER2-E subtype, no pCR was observed in the 4patients with immunohistochemical (IHC) HER2 2+/ISH-positive status in contrastto 20/39 (51.2%) pCRs in IHC HER2 3+ tumors. Centrally confirmed pCR rate in HR+/HER2+tumors was38.5% compared to 58.5% in HR-/HER2+ tumors. No new safety signals wereobserved. Conclusions: These are the first results of a neoadjuvant chemotherapy-free12-week de-escalation anti-HER2-regimen with trastuzumab and pertuzumab incombination with the PD-1 inhibitor pembrolizumab in patients with a HER2-E EBC.In the context of the WSG ADAPT HER2+ de-escalation trials the observed pCRrates compare favourably in HR+ as well as HR- HER2 EBC. Moreover, KEYRICHED-1demonstrates that with appropriate molecular patient selection clinicallymeaningful pCR rates in the range of those obtained with longer, more toxicchemotherapy-containing regimens can be achieved.

Citation Format: Sherko Kuemmel, Oleg Gluz, Mattea Reinisch, Athina Kostara, Iris Scheffen, Monika Graeser, Kerstin Luedtke-Heckenkamp, Andreas Hartkopf, Felix Hilpert, Angela Kentsch, Carsten Ziske, Reinhard Depenbusch, Michael Braun, Jens Blohmer, Christine zu Eulenburg, Matthias Christgen, Stephan Bartels, Hans Kreipe, Enrico Pelz, Peter Schmid, Nadia Harbeck. KEYRICHED-1 - A prospective, multicenter, open label, neoadjuvant phase II single arm study with pembrolizumab in combination with dual anti-HER2 blockade with trastuzumab and pertuzumab in early breast cancer patients with molecular HER2-enriched intrinsic subtype [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-03.

ERBB2 mutation is associated with sustained tumor cell proliferation after short-term preoperative endocrine therapy in early lobular breast cancer

Invasive lobular breast cancer (ILC) is a special breast cancer (BC) subtype and is mostly hormone receptor (HR)-positive and ERBB2 non-amplified. Endocrine therapy restrains tumor proliferation and is the mainstay of lobular BC treatment. Mutation of ERBB2 has been associated with recurrent ILC. However, it is unknown whether ERBB2 mutation impacts on the otherwise exquisite responsiveness of early ILC to endocrine therapy. We have recently profiled n = 622 HR-positive early BCs from the ADAPT trial for mutations in candidate genes involved in endocrine resistance, including ERBB2. All patients were treated with short-term preoperative endocrine therapy (pET, tamoxifen or aromatase inhibitors) before tumor resection. Tumor proliferation after endocrine therapy (post-pET Ki67 index) was determined prospectively by standardized central pathology assessment supported by computer-assisted image analysis. Sustained or suppressed proliferation were defined as post-pET Ki67 ≥10% or <10%. Here, we report a subgroup analysis pertaining to ILCs in this cohort. ILCs accounted for 179/622 (28.8%) cases. ILCs were enriched in mutations in CDH1 (124/179, 69.3%, P < 0.0001) and ERBB2 (14/179, 7.8%, P < 0.0001), but showed fewer mutations in TP53 (7/179, 3.9%, P = 0.0048) and GATA3 (11/179, 6.1%, P < 0.0001). Considering all BCs irrespective of subtypes, ERBB2 mutation was not associated with proliferation. In ILCs, however, ERBB2 mutations were 3.5-fold more common in cases with sustained post-pET proliferation compared to cases with suppressed post-pET proliferation (10/75, 13.3% versus 4/104, 3.8%, P = 0.0248). Moreover, ERBB2 mutation was associated with high Oncotype DX recurrence scores (P = 0.0087). In summary, our findings support that ERBB2 mutation influences endocrine responsiveness in early lobular BC.

TP53 mutations are associated with primary endocrine resistance in luminal early breast cancer

Background

Whereas the genomic landscape of endocrine‐resistant breast cancer has been intensely characterized in previously treated cases with local or distant recurrence, comparably little is known about genomic alterations conveying primary non‐responsiveness to endocrine treatment in luminal early breast cancer.

Methods

In this study, 622 estrogen receptor‐expressing breast cancer cases treated with short‐term preoperative endocrine therapy (pET) from the WSG‐ADAPT trial (NCT01779206) were analyzed for genetic alterations associated with impaired endocrine proliferative response (EPR) to 3‐week pET with tamoxifen or aromatase inhibitors. EPR was categorized as optimal (post‐pET Ki67 <10%) versus slightly, moderately, and severely impaired (post‐pET Ki67 10%–19%, 20%–34%, and ≥35%, respectively). Recently described gene mutations frequently found in previously treated advanced breast cancer were analyzed (ARID1A, BRAF, ERBB2, ESR1, GATA3, HRAS, KRAS, NRAS, PIK3CA, and TP53) by next‐generation sequencing. Amplifications of CCND1, FGFR1, ERBB2, and PAK1 were determined by digital PCR or fluorescence in situ hybridization.

Results

ERBB2 amplification (p = 0.0015) and mutations of TP53 (p < 0.0001) were significantly associated with impaired EPR. Impaired EPR in TP53‐mutated breast cancer cases was independent from the Oncotype DX Recurrence Score group and was seen both with tamoxifen‐ and aromatase inhibitor‐based pET (p = 0.0005 each).

Conclusion

We conclude that impaired EPR to pET is suitable to identify cases with primary endocrine resistance in early luminal breast cancer and that TP53‐mutated luminal cancers might not be sufficiently treated by endocrine therapy alone.

Prognostic impact of recurrence score, endocrine response and clinical-pathological factors in high-risk luminal breast cancer: Results from the WSG-ADAPT HR+/HER2- chemotherapy trial

504

Background: In HR+/HER2- N0-1 early BC, postmenopausal patients (pts) with RS™ > 25 and a substantial proportion of premenopausal pts seem to benefit from addition of adjuvant chemotherapy (CT) to endocrine therapy (ET). However, the magnitude of absolute benefit from this treatment intensification seems to depend on clinical-pathological and biological prognostic factors. For the first time, we present outcome from the CT part of the prospective phase III WSG-ADAPT HR+/HER- trial combining both static (RS in baseline core biopsy (CB) and dynamic (Ki67 response) biomarkers to optimize adjuvant therapy in luminal EBC. Methods: Pts with clinically high-risk HR+/HER2- EBC (cT2-4 OR clinically N+ OR G3 OR Ki67>15%) were initially treated by 3 (+/-1) weeks of standard ET (postmenopausal: mostly AI; premenopausal: TAM) before surgery or sequential CB. Pts with cN2-3 or G3/Ki67>40% were randomized directly to the CT trial. pN0-1 pts with RS0-11 OR RS12-25/ET-response (central Ki67postendocrine<10%) received ET alone; the remaining high-risk cohort was randomized to the CT trial: (neo)adjuvant dose-dense CT (4xPaclitaxelà4xEC q2w vs. 8xNab-Paclitaxel q1wà4xEC q2w) followed by ET. Primary endpoint is efficacy comparison of CT schedules for survival; secondary endpoints reported here involve impacts of key prognostic factors on survival. Kaplan-Meier and Cox proportional hazard models were used to estimate survival curves and hazard ratios. For this analysis, subgroups free of selection bias by RS/ET-response were defined. Results: 5625 pts were screened and 4621 (ITT) entered the trial. After 4.9y median follow-up, higher baseline and post-endocrine Ki-67 levels were associated with poorer iDFS (both p < 0.001). In the CT cohort (n = 2331), higher RS, nodal status, and tumor size were generally associated with poorer iDFS. However, iDFS differed between N1 and N0 status only among younger pts (<50 years). In pts with >4 positive LN (n = 390), lower RS was associated with improved iDFS (RS0-11 vs RS > 25: plog-rank= 0.016, 5y-iDFS 90% vs. 64%). In pts with RS > 25 (n = 965), low Ki67postendocrine, N0 status, and c/pT1 status were associated with improved iDFS. In particular, ET-responders had higher 5y-iDFS (84%) than ET-non-responders (77%; plog-rank= 0.040). Younger patients (<50 years old) with N0-1 RS 12-25/ ET-non-responders treated by CT had non-significantly poorer 5-year iDFS (89%) compared to those with ET-response treated by ET only (92%) (plog-rank= 0.249). Conclusion: First results from the prospective high risk cohort from a large prospective phase III ADAPT trial provide evidence for good prognosis in some pts with >4 positive LN and e.g. low RS. Moreover combination of lower post-endocrine Ki-67 and limited tumor burden may be a promising criterion for CT de-escalation strategies even in patients with high RS. Clinical trial information: NCT01779206.

De-escalated neoadjuvant pertuzumab+trastuzumab with or without paclitaxel weekly in HR-/HER2+ early breast cancer: ADAPT-HR-/HER2+ biomarker and survival results

503

Background: Optimal use of de-escalated, particularly chemotherapy(CT)-free, neoadjuvant regimens in HER2+ early breast cancer (EBC) is currently unclear as there are limited survival data so far. In ADAPT-HR-/HER2+, we previously showed an excellent pCR rate of 90% after 12-week neoadjuvant paclitaxel (Pac) +pertuzumab (P) +trastuzumab (T) and a substantial and clinically meaningful pCR rate of 34% after P+T alone in HR-/HER2+ EBC. Here, we present first survival data. Methods: The prospective multicenter WSG-ADAPT-HR-/HER2+ phase II-trial is part of the ADAPT-umbrella protocol. Patients with cT1-cT4c, cN0-3 HR-/HER2+ EBC (n = 134) were randomized to 4 cycles of P+T +/- pac d1,8,15 q3w. All tumors were HR-negative (ER and PR < 1%) and HER2-positive (central lab, i.e., 2+ FISH positive or 3+ by immunohistochemistry. Primary endpoint was pCR (ypT0/is/ypN0); omission of further CT was allowed in pts with pCR. Trial objective was to compare pCR in P+T+pac arm vs. early responders in P+T arm (defined as low cellularity and/or Ki67 decrease >30% after 3 weeks). The trial was stopped early due to the observed pCR superiority in the P+T+pac arm. Secondary endpoints included safety, 5-y (distant)-DFS, OS and translational research. Cox-regression analysis was applied. PAM50 subtype was assessed using the BC360 panel. Results: 134 patients were randomized to P+T (n = 92) or P+T+pac (n = 42). 60% of tumors were cT2-4, 42% clinically node-positive. After a median follow-up of 5 years, no significant differences between study arms were observed regarding DFS, dDFS, and OS; only 13 iDFS events (7 dDFS) were observed in the whole ITT population. pCR (vs. non-pCR) after the 12-week study treatment (irrespective of study arm) was strongly associated with improved iDFS (5y DFS 98.5% vs. 82%, HR = 0.14, 95% CI 0.03-0.64). Of the 69 patients with pCR, 39 (56.5%) received no further CT (P+T arm: n = 9, 29% vs. (P+T+pac arm n = 30, 79%); only 1 distant relapse (1.4%) was observed in these patients. In the CT-free P+T arm, no pCR was observed in patients with low HER2 expression (IHC 1+/2+ and FISH positive) and/or basal-like subtype by PAM50 (n = 17, 19%). In the total study population, low HER2 expression and/or no early response was strongly associated with worse dDFS (p =.029) and iDFS (p =.068). No new safety signals were observed. Conclusions: For the first time, we have shown both excellent pCR and survival in patients treated by de-escalated neoadjuvant CT+P+T irrespective of further CT use in a prospective multicenter study. Investigation of CT-free regimens may need to be focussed on selected patients only (e.g. with high HER2 expression/non-basal-like tumors). In ADAPT HR-/HER2+, early pCR after only 12 weeks of neoadjuvant P+T+pac was strongly associated with improved outcome and may thus serve as a predictive clinical marker for further treatment (de)-escalation. Clinical trial information: NCT01779206.

Early response by MR imaging and ultrasound as predictor of pathologic complete response to 12-week neoadjuvant therapy for different early breast cancer subtypes: Combined analysis from the WSG ADAPT subtrials

We evaluated the role of early response after 3 weeks of neoadjuvant treatment (NAT) assessed by ultrasound (US), magnetic resonance imaging (MRI) and Ki-67 dynamics for prediction of pathologic complete response (pCR) in different early breast cancer subtypes. Patients with HR+/HER2+, HR-/HER2- and HR-/HER2+ tumors enrolled into three neoadjuvant WSG ADAPT subtrials underwent US, MRI and Ki-67 assessment at diagnosis and after 3 weeks of NAT. Early response was defined as complete or partial response (US, MRI) and ≥30% proliferation decrease or <500 invasive tumor cells (Ki-67). Predictive values and area under the receiver operating characteristic (AUC) curves for prediction of pCR (ypT0/is ypN0) after 12-week NAT were calculated. Two hundred twenty-six had MRI and 401 US; 107 underwent both MRI and US. All three methods yielded a similar AUC in HR+/HER2+ (0.66-0.67) and HR-/HER2- tumors (0.53-0.63), while MRI and Ki-67 performed better than US in HR-/HER2+ tumors (0.83 and 0.79 vs 0.56). Adding MRI+/-Ki-67 increased AUC of US in HR-/HER2+ tumors to 0.64 to 0.75. MRI and Ki-67 demonstrated highest sensitivity in HR-/HER2- (0.8-1) and HR-/HER2+ tumors (1, both). Negative predictive value was similar for all methods in HR+/HER2+ (0.71-0.74) and HR-/HER2- tumors (0.85-1), while it was higher for MRI and Ki-67 compared to US in HR-/HER2+ subtype (1 vs 0.5). Early response assessed by US, MRI and Ki-67 is a strong predictor for pCR after 12-week NAT. Strength of pCR prediction varies according to tumor subtype. Adding MRI+/-Ki-67 to US did not improve pCR prediction in majority of our patients.

Immune cell composition and functional marker dynamics from multiplexed immunohistochemistry to predict response to neoadjuvant chemotherapy in the WSG-ADAPT-TN trial

BACKGROUND

The association of early changes in the immune infiltrate during neoadjuvant chemotherapy (NACT) with pathological complete response (pCR) in triple-negative breast cancer (TNBC) remains unexplored.

METHODS

Multiplexed immunohistochemistry was performed in matched tumor biopsies obtained at baseline and after 3 weeks of NACT from 66 patients from the West German Study Group Adjuvant Dynamic Marker-Adjusted Personalized Therapy Trial Optimizing Risk Assessment and Therapy Response Prediction in Early Breast Cancer - Triple Negative Breast Cancer (WSG-ADAPT-TN) trial. Association between CD4, CD8, CD73, T cells, PD1-positive CD4 and CD8 cells, and PDL1 levels in stroma and/or tumor at baseline, week 3 and 3-week change with pCR was evaluated with univariable logistic regression.

RESULTS

Compared with no change in immune cell composition and functional markers, transition from 'cold' to 'hot' (below-median and above-median marker level at baseline, respectively) suggested higher pCR rates for PD1-positive CD4 (tumor: OR=1.55, 95% CI 0.45 to 5.42; stroma: OR=2.65, 95% CI 0.65 to 10.71) and PD1-positive CD8 infiltrates (tumor: OR=1.77, 95% CI 0.60 to 5.20; stroma: OR=1.25, 95% CI 0.41 to 3.84; tumor+stroma: OR=1.62, 95% CI 0.51 to 5.12). No pCR was observed after 'hot-to-cold' transition in PD1-positive CD8 cells. pCR rates appeared lower after hot-to-cold transitions in T cells (tumor: OR=0.26, 95% CI 0.03 to 2.34; stroma: OR=0.35, 95% CI 0.04 to 3.25; tumor+stroma: OR=0.00, 95% CI 0.00 to 1.04) and PD1-positive CD4 cells (tumor: OR=0.60, 95% CI 0.11 to 3.35; stroma: OR=0.22, 95% CI 0.03 to 1.92; tumor+stroma: OR=0.32, 95% CI 0.04 to 2.94). Higher pCR rates collated with 'altered' distribution (levels below-median and above-median in tumor and stroma, respectively) of T cell (OR=3.50, 95% CI 0.84 to 14.56) and PD1-positive CD4 cells (OR=4.50, 95% CI 1.01 to 20.14).

CONCLUSION

Our exploratory findings indicate that comprehensive analysis of early immune infiltrate dynamics complements currently investigated predictive markers for pCR and may have a potential to improve guidance for individualized de-escalation/escalation strategies in TNBC.

Magnetic resonance imaging and ultrasound for prediction of residual tumor size in early breast cancer within the ADAPT subtrials

Background

Prediction of histological tumor size by post-neoadjuvant therapy (NAT) ultrasound and magnetic resonance imaging (MRI) was evaluated in different breast cancer subtypes.

Methods

Imaging was performed after 12-week NAT in patients enrolled into three neoadjuvant WSG ADAPT subtrials. Imaging performance was analyzed for prediction of residual tumor measuring ≤10 mm and summarized using positive (PPV) and negative (NPV) predictive values.

Results

A total of 248 and 588 patients had MRI and ultrasound, respectively. Tumor size was over- or underestimated by < 10 mm in 4.4% and 21.8% of patients by MRI and in 10.2% and 15.8% by ultrasound. Overall, NPV (proportion of correctly predicted tumor size ≤10 mm) of MRI and ultrasound was 0.92 and 0.83; PPV (correctly predicted tumor size > 10 mm) was 0.52 and 0.61. MRI demonstrated a higher NPV and lower PPV than ultrasound in hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-positive and in HR−/HER2+ tumors. Both methods had a comparable NPV and PPV in HR−/HER2− tumors.

Conclusions

In HR+/HER2+ and HR−/HER2+ breast cancer, MRI is less likely than ultrasound to underestimate while ultrasound is associated with a lower risk to overestimate tumor size. These findings may help to select the most optimal imaging approach for planning surgery after NAT.

Trial registration

Clinicaltrials.gov, NCT01815242 (registered on March 21, 2013), NCT01817452 (registered on March 25, 2013), and NCT01779206 (registered on January 30, 2013).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01413-y.

Abstract OT-01-02: Adaptlate -a randomized, controlled, open-label, phase-iii trial on adjuvant dynamic marker - adjusted personalized therapy comparing abemaciclib combined with standard adjuvant endocrine therapy versus standard adjuvant endocrine therapy in (clinical or genomic) high risk, hr+/her2- early breast cancer

Goals: The WSG ADAPT trial program is one of the first new generation trials addressing the issue of individualization of (neo)-adjuvant decision-making in early breast cancer (EBC) in a subtype-specific manner. The first WSG ADAPT umbrella trial (NCT01779206) aimed to establish early predictive molecular surrogate markers for response after a short 3-week induction treatment and to omit chemotherapy in a large cohort of early high risk HR+/HER2- patients. The aim of the ADAPTlate phase-III-trial is to improve adjuvant therapy for patients at high risk for late disease recurrence, who have completed definite locoregional therapy (with or without neoadjuvant or adjuvant chemotherapy) and are under adjuvant endocrine treatment. This high-risk population does not derive optimal benefit from standard ET, often develops secondary resistance against ET and consequently late recurrences. With ADAPTlate, it is planned to evaluate whether patients with high-risk EBC derive additional benefit from adding abemaciclib to ET even 2-6 year after their initial diagnosis. Abemaciclib has been shown to improve outcome in metastatic breast cancer and recently, even in early breast cancer when given as part of primary therapy. Methods: WSG-ADAPTcycle is a prospective, multi-center, interventional, two-arm, non-blinded, randomized, controlled adjuvant phase III trial (NCT not yet assigned). It investigates whether patients with HR+/HER2- EBC identified as high-risk during screening (based on clinical or genomic risk) derive additional benefit from 2 years of the CDK4/6 inhibitor abemaciclib combined with ET compared to ET alone. Starting Q3 2020 (enrollment 36 months, 50 sites), 1250 patients will be screened and 903 randomized in a ratio 3:2 (602 to abemaciclib + ET; 301 to standard ET). Pre-/postmenopausal patients with histologically confirmed invasive HR+/HER2- EBC and 2-6 years after primary diagnosis, with either known high clinical risk (c/pN 2-3 OR high CTS score in pN 0-1 OR non-pCR after neoadjuvant chemotherapy in cN 1 or G3 tumors OR G3 and Ki-67 ≥ 40% in pN 0-1) or known high genomic risk (Oncotype Dx® / RS &gt;25 in c/pN 0, RS &gt;18 in c/pN 1 OR high risk Prosigna®, EPclin® or Mammaprint® in pN 0-1) or intermediate clinical, but unknown genomic risk (luminal B-like (G3 or Ki-67 ≥20%) in c/pN 0-1 AND Oncotype DX® in screening either RS &gt;25 in c/pN 0 or RS &gt;18 in c/p N1) will be eligible. Treatment duration is 2 years for the interventional abemaciclib + ET (premenopausal: AI+GnRH) arm, followed by at least 3-6 years ET alone. Patients in control arm will receive 5-8-years ET at investigator´s choice. ePROs are collected using CANKADO. Primary objective is to demonstrate superiority of invasive disease-free survival (iDFS) of abemaciclib + ET vs. standard ET. Secondary objectives include overall survival (OS), distant disease-free survival (dDFS), occurrence of CNS metastases, quality of life (EORTC QLQ-C30, QLQ-BR23, EQ-5D-5L) and translational research. Translational analyses: Exploratory tissue biomarker research will be conducted to assess alterations in molecular markers (e.g., ESR1, PIK3CA, CCND1, CDKN2A, RB1). In addition, ctDNA/ctRNA from optional blood samples will be assessed for mutations and gene expression relevant for HR+/HER2- EBC using the most appropriate technology at the time of testing. Conclusions: ADAPTlate seeks to evaluate whether enhancing ET with a CDK 4/6 inhibitor is superior to ET alone in patients with clinical or genomic high risk EBC even 2-6 years after their initial diagnosis. Translational research aims at assessing potential mechanisms of resistance to endocrine and/or CDK4/6 targeted therapy.

Citation Format: Oleg Gluz, Tom Degenhardt, Norbert Marschner, Matthias Christgen, Hans Heinrich Kreipe, Ulrike Nitz, Ronald Kates, Timo Schinkoethe, Monika Graeser, Rachel Würstlein, Sherko Kuemmel, Nadia Harbeck, West German Study Group. Adaptlate -a randomized, controlled, open-label, phase-iii trial on adjuvant dynamic marker - adjusted personalized therapy comparing abemaciclib combined with standard adjuvant endocrine therapy versus standard adjuvant endocrine therapy in (clinical or genomic) high risk, hr+/her2- early breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr OT-01-02.

Abstract GS4-03: Neoadjuvant nab-paclitaxel weekly versus dose-dense paclitaxel followed by dose-dense EC in high risk HR+/HER2- early BC by: Results from the neoadjuvant part of ADAPT HR+/HER2- trial

Background: Pathological complete response (pCR) is associated with improved outcome in patients with high-risk HR+/HER2- breast cancer (BC) but the use of (neo)adjuvant chemotherapy in early HR+/HER2- BC remains controversial. Oncotype DX / Recurrence Score (RS) and dynamic Ki67 response after short preoperative endocrine therapy are potentially predictive for pCR. Still, no prospective data are available so far to predict chemotherapy efficacy in this key patient group. Use of dose-dense chemotherapy is associated with improved outcome in meta-analysis, but its use in the neoadjuvant setting is less studied. Furthermore, use of nab-paclitaxel instead of solvent-based paclitaxel has shown promising results in some studies. Here, we present for the first time data from a randomized prospective trial comparing these risk-selection strategies according to RS and Ki67 decrease in high-risk HR+/HER2- BC. Methods: High-risk BC patients [cN0-1 with RS&gt;25 or (RS 12-25 AND (centrally measured) post-endocrine Ki67 &gt;10%] OR [cN2-3 status] OR [G3 AND Ki67&gt;40%] were randomized to (neo)adjuvant 4x paclitaxel175 q2w or 8xnab-paclitaxel 125 mg/m2q1w followed by 4x E90C600 q2w. pCR was defined as no invasive tumor in breast and lymph nodes. Results: 858 patients with available surgery data randomized to neoadjuvant Pac-EC (N=423) or nab-Pac-EC (N=435) were analyzed. Median age was 51 years; median RS was 30 (N=572); 34% had node-positive; 46% (locally) G3 tumors. Baseline characteristics were well balanced between study arms. Patients receiving nab-Pac-EC had higher pCR than those with Pac-EC (20.3% vs. 12.3%, p=.002); patients with RS&lt;25 (about 27%) had a lower pCR rate than those with RS&gt;25 (6.5% vs. 15.8%, p=.003). The association of RS with pCR appeared more pronounced in premenopausal women, but a test of interaction was not significant; RS was about 3 points higher (mean 32.9 vs. 29.8, p&lt;.001) in postmenopausal cases (p=.001). Clinical tumor stage cT2-4 was reported in 65%, with a lower pCR rate than in cT1 tumors (14% vs. 20%, p=.02). RS was moderately correlated (R=.45) with baseline Ki67. In multivariable analysis with tumor stage, RS, Ki67, menopausal status, and ER and PR positivity, higher RS and cT1 stage were favorable for pCR. Excluding RS, higher Ki67 and lower ER (as well as cT1) were favorable. In patients with RS&lt;25, there was no pCR with Pac-EC (0/72 pCR); pCR was almost 20% with RS&gt;25 and nab-Pac-EC. Further details and data including impacts of Ki67 dynamics and additional markers on pCR will be presented at the meeting. Conclusions: Use of neoadjuvant nab-paclitaxel instead of solvent-based paclitaxel appears promising within a short (16-weeks) dose-dense chemotherapy schedule in high-risk HR+/HER2- BC. For the first time, data from a large neoadjuvant randomized trial confirm RS could help to select patients for neoadjuvant chemotherapy in high-risk HR+/HER2- breast cancer (BC).

Citation Format: Sherko Kuemmel, Oleg Gluz, Ulrike Nitz, Michael Braun, Matthias Christgen, Kerstin Luedtke-Heckenkamp, Raquel von Schumann, Maren Darsow, Helmut Forstbauer, Jochem Potenberg, Eva-Maria Grischke, Bahriye Aktas, Claudia Schumacher, Ronald Kates, Monika Graeser, Rachel Wuerstlein, Christoph Uleer, Michael Hauptmann, Steve Shak, Rick Baehner, Hans Kreipe, Nadia Harbeck, West German Study Group. Neoadjuvant nab-paclitaxel weekly versus dose-dense paclitaxel followed by dose-dense EC in high risk HR+/HER2- early BC by: Results from the neoadjuvant part of ADAPT HR+/HER2- trial [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr GS4-03.

Differential impact of prognostic parameters in hormone receptor-positive lobular breast cancer

BACKGROUND

Invasive lobular breast cancer (BC) is the second most common BC subtype. Prognostic parameters (tumor classification, lymph node status, histologic grade, Oncotype DX recurrence score [RS], progesterone receptor status, and Ki67 index) were retrospectively studied in a large, prospective clinical trial encompassing 2585 patients who had hormone receptor-positive early BC (the West German Study Group PlanB trial).

METHODS

BCs were centrally reviewed and classified as lobular (n = 353; 14%) or nonlobular (n = 2232; 86%). The median follow-up was 60 months. Five-year disease-free survival (DFS) estimates were obtained using the Kaplan-Meier method. Prognostic parameters were evaluated using Cox proportional hazard models.

RESULTS

Lobular BC was associated with higher tumor classification, higher lymph node status, lower histologic grade, lower Ki67 index, and low or intermediate RS. The prevalence of high RS (RS range, 26-100) was 3-fold lower in patients who had lobular BC compared with those who had nonlobular BC (8% vs 24%; P < .001). However, 5-year DFS estimates for lobular and nonlobular BC were similar (92.1% and 92.3%, respectively; P = .673). In multivariate analyses, prognostic parameters for DFS in lobular BC included grade 3 (hazard ratio, 5.06; 95% CI, 1.91-13.39) and a pathologic lymph node status (pN) of pN3 (hazard ratio, 12.16; 95% CI, 3.87-38.24), but not RS. By contrast, prognostic parameters in nonlobular BC included grade 3 (hazard ratio, 1.65; 95% CI, 1.11-2.44), pN3 (hazard ratio, 3.68; 95% CI, 1.60-8.46), and high RS (hazard ratio, 2.49; 95% CI, 1.69-3.68).

CONCLUSIONS

Lobular BC is associated with low and intermediate RS, although 5-year DFS is similar to that of nonlobular BC. The effect of the RS in lobular BC appears to be distinct from that in nonlobular BC. For risk assessment, the RS needs to be complemented by clinicopathologic parameters for therapy decision making.

ADAPTcycle: Adjuvant dynamic marker-adjusted personalized therapy (ADAPT) comparing endocrine therapy plus ribociclib versus chemotherapy in intermediate-risk HR+/HER2- early breast cancer (EBC)

TPS601

Background: The WSG ADAPT trial program represents the concept of individualization of (neo)-adjuvant decision-making in EBC in a subtype-specific manner. The first WSG ADAPT umbrella trial aimed to establish early predictive molecular surrogate markers for response after a short 3-week induction treatment. The goals of the WSG ADAPT trial program are early response assessment and subtype-specific therapy tailoring to those patients who are most likely to benefit. Methods: WSG-ADAPTcycle is a prospective, multi-center, interventional, two-arm, open-label, (neo)adjuvant, non-blinded, randomized, controlled phase III trial (NCT04055493). It investigates whether patients (pts.) with HR+/HER2- EBC identified during screening as intermediate risk (based on Oncotype DX and response to 3 weeks of preoperative endocrine therapy [ET]) derive additional benefit from 2 years of the CDK4/6 inhibitor ribociclib combined with ET compared to chemotherapy (CT) (followed by standard ET). Co-primary endpoints are disease-free survival (DFS) and distant DFS. It is planned to screen 5600 pts and to randomize 1670 pts in a 3:2 ratio (ribociclib + ET/CT). Study start was in July 2019 (80 sites, enrollment period 36 months) and until date of submission, 180 pts. have been screened and 40 randomized. Pts with HR+/HER2- EBC with clinically enhanced risk (cT2-4 or Ki67 20% or G3 or cN+) are eligible if they fulfill the ADAPT intermediate-risk group criteria: either Recurrence Score (RS) ≤25 and Ki67postendocrine>10%, RS >25 and Ki67postendocrine<10% in p/cN0-1 pts, or RS ≤25 and Ki67postendocrine<10% in c/pN2-3 pts. Treatment duration is 2 years for the ribociclib + ET (premenopausal: AI + GnRH) arm and 16-24 weeks for the CT arm; treatment is possible either in the neoadjuvant (ET + ribociclib duration 16 – 32 weeks) or adjuvant setting. ePROs are collected using CANKADO; ECG monitoring is performed using a novel cardiology-supported CANKADO-based eHealth method. Translational analyses: Exploratory tissue biomarker research will be conducted to assess alterations in molecular markers. In addition, ctDNA/ctRNA from optional blood samples will be assessed for mutations and gene expression. Conclusions: ADAPTcycle seeks to evaluate whether endocrine-based therapy with ET and a CDK 4/6 inhibitor is superior to CT followed by ET in patients with luminal EBC who may be undertreated with ET alone (based on either lack of endocrine responsiveness or high tumor burden). Clinical trial information: 2018-003749-40 .

De-escalated chemotherapy versus endocrine therapy plus pertuzumab+ trastuzumab for HR+/HER2+ early breast cancer (BC): First efficacy results from the neoadjuvant WSG-TP-II study

515

Background: HR+/HER2+ breast cancer (BC) is a distinct entity associated with better prognosis compared to HR-/HER2+ BC. However, combination of chemotherapy (CT) with (dual) anti-HER2 blockade is standard in HER2+ early BC (EBC), irrespective of HR-status. Despite of some promising data on combination of endocrine therapy (ET) with dual anti-HER2 blockade in EBC and metastatic HR+/HER2+ BC, no prospective comparison of neoadjuvant CT vs. ET + dual HER2-blockade has yet been performed. Methods: In the prospective WSG TP-II phase II-trial (NCT03272477; Sponsor: Palleos GmbH, Wiesbaden, Germany), 207 patients (pts) (257 screened; 40 centers) with centrally confirmed HR+/HER2+ EBC were randomized to 12 weeks of standard ET (n=100) vs. paclitaxel 80 mg/m2 weekly (n=107) +trastuzumab+pertuzumab q3w for all pts. Primary endpoint was pCR (ypT0/is/ypN0). Secondary endpoints include safety, disease-free and overall survival, translational research, and quality of life (QoL). Omission of further CT was allowed in all pts with pCR; dual HER2-blockade was administered in the adjuvant setting in all pts. Results: Baseline characteristics were well balanced between the arms. Median age was 53 years; 58% had cT2-4, 28% had cN+; 43% had G3 tumors. pCR data were available in 198 pts (ET: n=96; Pac: n=102). pCR was observed in 24% (95% CI: 16-34%) with ET+T+P vs. 57% (95% CI:47-67%) with Pac+T+P (OR 0.24, 95% CI: 0-0.46, p<0.001). In multivariable logistic regression analysis and corresponding sensitivity analysis (bootstrap/subsample inclusion frequencies and lasso regression) including study arm, BMI, menopausal, cT, and cN status, histological grade, HER2-status, Ki67, ER, PR as continuous variables, only study arm and HER2 3+ status were significantly associated with pCR. Neoadjuvant treatment was well tolerated in both study arms and completed per protocol in 93/92 (ET+P+T/Pac+P+T) patients. Only 9/13 SAEs (ET+P+T/Pac+P+T) were reported during neoadjuvant therapy. PAM50 and QoL analysis are ongoing. Conclusions: WSG TP-II is the first randomized prospective trial comparing two neoadjuvant de-escalation treatments in HR+/HER2+ EBC. The excellent pCR rate of 57% after only 12 weeks of Pac+P+T was clearly superior to the still promising 24% pCR rate in pts treated by ET+P+T. In both arms, treatment efficacy was most pronounced in HER2 3+ tumors. Survival results need to be awaited before definite recommendations for a de-escalated regimen in HR+/HER2+ EBC can be made. Clinical trial information: 2016-005157-21 .

Association of TILs with clinical parameters, Recurrence Score® results, and prognosis in patients with early HER2-negative breast cancer (BC)-a translational analysis of the prospective WSG PlanB trial

BACKGROUND

The presence of tumor-infiltrating lymphocytes has been associated with prognosis and chemotherapy response, particularly in high-risk breast cancer subtypes. There is limited data so far as to (i) how tumor-infiltrating lymphocyte (TIL) measurements correlate with genomic measurements such as the Oncotype DX Recurrence Score® and (ii) whether the survival impact of TIL measurements varies according to different adjuvant systemic therapies.

METHODS

The WSG PlanB trial compared an anthracycline-free chemotherapy regimen (6x docetaxel/cyclophosphamide, TC) to an anthracycline-taxane sequence (4xEC followed by 4x docetaxel) in patients with intermediate-risk, HER2-negative early breast cancer (EBC). Patients with HR-positive HER2-negative EBC were further stratified to receive endocrine therapy alone vs. chemotherapy followed by endocrine therapy based on Recurrence Score results and nodal status. In this analysis, three independent observers quantified and categorized the presence of TILs among tumor samples from patients in PlanB. TIL measurements were correlated with clinical/pathological parameters and treatment outcome overall and according to the treatment arm.

RESULTS

Disease-free survival (DFS) rates were significantly better (p = .04) in HR-negative patients with high vs. intermediate TIL levels and were higher in low vs. intermediate TIL patients, however with borderline significance only (p = .06). There were no significant differences among TIL categories in HR+ patients. High RS categories, HR-negative status, and high KI67 were independently and significantly associated with high TIL categories. There was no significant impact of TIL category on DFS in patients treated by endocrine therapy only; however, in patients receiving chemotherapy, DFS in the intermediate TIL category was lower than that in the other categories.

CONCLUSION

Although the presence of high TILs is associated with negative prognostic parameters such as high KI67 and HR-negative status among patients with HR-positive HER2-negative EBC, patients with high TILs show a favorable 5-year DFS in both HR-positive/HER2-negative and triple-negative breast cancer.

Abstract P2-16-05: Efficacy of response- and toxicity-guided neoadjuvant chemotherapy in elderly early breast cancer patients: Results of WSG ADAPT elderly sub-trial

Introduction: More than 1/3 of early breast cancers (EBC) are diagnosed in women ≥ 70 years. Although polychemotherapy has been shown to be more effective than monochemotherapy also in these patients, only limited prospective data on efficacy of neoadjuvant therapy are available so far. Here, we present results of the prospective ADAPT Elderly sub-study from the WSG ADAPT umbrella protocol.

Methods: Patients ≥70 years with high-risk HR+/HER2- EBC (i.e. Recurrence Score (RS)&gt;25 or RS 12-25 with post-endocrine Ki67 of &gt;10% or ≥cN2) or HR-/HER2- EBC were treated by 2 cycles of liposomal doxorubicin (Myocet® 60 mg/m2)/cyclophosphamide 600 mg/m2 (MC). In case of clinical response by ultrasound (&gt;50% reduction in the sum of two largest diameters) and no AE grade 3-4, patients received an additional 2 cycles MC, otherwise they were switched to 6 cycles of paclitaxel (80 mg/m2) weekly. A sample size of n=150 was planned to demonstrate non-inferiority of the response- and toxicity-guided regimen vs. 4 cycles MC in responding patients (25% assumed pCR). The study was stopped early due to slow recruitment.

Results: Between 09/2014 and 10/2015, 83 EBC patients from 31 centers were registered; 78 started with therapy (40 HR+/HER2-; 38 HR-/HER2-). Median age was 74 years. 64% had G3 tumors, 66% cT24, and 34% cN+. Median Ki67 was 40%. 75/78 pts underwent stratification after 2 cycles; 1 pt withdrew consent: 45(61%) were responders with no severe toxicities, 29 (39%) non-responders or suffered toxicity grade 3-4. Surgical information is available in 72 patients (43 responder/no toxicity, 29 no response/toxicity groups respectively). pCR was observed in 7 patients in the responder/no toxicity group (i.e. 16% irrespective of HR status) and in n=3 patients in the no response/toxicity group (10%). Updated efficacy and safety data will be presented at the meeting.

Discussion: In one of the largest neoadjuvant chemotherapy-studies specifically for elderly pts with HER2- EBC, we observed a lower than expected pCR rate after 4 cycles of anthracycline-containing neoadjuvant chemotherapy. Taxane-based standard chemotherapy may thus be preferable in this population. Nevertheless, neoadjuvant chemotherapy seems feasible in elderly pts with high-risk HER2- EBC and should further be explored in the context of potential pCR-based (de)escalation strategies.

Citation Format: Sherko Kuemmel, Oleg Gluz, Matthias Christgen, Jochem Potenberg, John Hackmann, Raquel von Schumann, Monika Graeser, Marina Mangold, Rachel Wuerstlein, Ronald Kates, Hans H. Kreipe, Ulrike Nitz, Nadia Harbeck, West German Study Group. Efficacy of response- and toxicity-guided neoadjuvant chemotherapy in elderly early breast cancer patients: Results of WSG ADAPT elderly sub-trial [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-16-05.

Abstract P4-10-05: Predictive value of HER2 expression, early response and tumor infiltrating lymphocytes (TILs) on efficacy of de-escalated pertuzumab+trastuzumab in the neoadjuvant WSG-ADAPT-HER2+/HR- trial

Purpose: Only limited data are available on predictive markers for use of chemotherapy-free, anti-HER2 combinations in HER2-positive early breast cancer (eBC), in particular within the molecularly distinct HER2+/HR- subgroup.

Background: In the ADAPT HER2+/HR- trial, a promising pCR of about 43-45% was found in patients treated by 4 cycles of pertuzumab and trastuzumab with either defined early response (low tumor cellularity or relative Ki-67 decrease ≥30%) or indeterminate early response (e.g. no visible tumor by ultrasound), compared to under 10% in early non-responders. In addition to early response, HER2 protein expression and stromal TIL (s-TIL) dynamics after one cycle of therapy are promising tools for identification of patients with high likelihood of pathological complete response (pCR) after therapy with double anti-HER2 blockade (e.g. by lapatinib+trastuzumab) or T-DM1.

Methods: Patients with cT1-cT4c, cN0-3 early HER2+/HR- BC (n=134) were treated with 4 cycles of P+T +/- paclitaxel d1,8,15 q3w. Primary endpoint of the study was pCR (ypT0/is, ypN0). All tumors were HR-negative (ER and PR&lt;1%) and locally HER2 positive, i.e., 2+ with positive FISH or 3+ by immunohistochemistry (IHC). HR and HER2 status were confirmed by central pathology prior to randomization.

Tumors were classified as “HER2-low” if HER2-1+ or HER2-2+ by either local or central IHC assessment, otherwise “HER2-high”. s-TILs were measured semi-quantitively according to current international consensus in triplicate at baseline and on-treatment (at cycle 2); the median of the three measurements was taken to define the quantities TIL-0 and TIL-3, respectively. “Lymphocyte-dominant subtype” at baseline and cycle 2 were defined as TIL-0≥40% and TIL-3≥40%, respectively.

The present analysis characterizes the predictive impact of early response HER2 protein expression, and s-TILs on pCR under dual anti-HER2 therapy for the first time within a prospective neoadjuvant trial specific to the HER2+/HR- BC subtype.

Results: As previously reported, pCR was 34.4% without chemotherapy and 90.5% with chemotherapy. TIL-0 and TIL-3 were available in n=119/134 and n=103/134 patients, respectively. TIL-0 and TIL-3 were not significantly associated with pCR in the whole cohort or within the T+P arm, either modeled as a continuous variable or in terms of binary variables representing lymphocyte-dominant subtype or defined by the respective population medians.

HER2-high expression was found in 87% of patients. In the T+P arm, pCR was much higher in HER2-high than HER2-low patients (40.3% vs. 0%, p=.003).

In the T+P arm, 24 and 38 of 92 patients were classified as non- and responders, unclassified early response was observed in 30 of 92 patients. pCR in these groups were 8.3% vs. 44.7% vs. 42.9% respectively. Higher baseline TILs were positively associated with early response.

Clinically meaningful pCR of 49% after only 4 cycles of chemotherapy-free P+T was seen in those patients with early response after one cycle of therapy and HER2-high classification, compared to 11.8% in the HER2-high/non-responder group).

Conclusions: At present, a combination of baseline high HER2 expression with low cellularity after one cycle of neoadjuvant therapy – rather than s-TIL determination (at baseline or in response to therapy) – appears to be a simple and feasible tool for identification of candidates for de-escalated treatment in HER2+/HR- disease. Further research on high-precision determination of HER2-high expression (by immunohistochemistry vs. mRNA-based tools) is strongly needed for optimal patient selection for future chemotherapy de-escalation trials.

Citation Format: Oleg Gluz, Cornelia Kolberg-Liedtke, Claudia Biehl, Matthias Christgen, Sherko Kuemmel, Eva-Maria Grischke, Doris Augustin, Michael Braun, Jochem Potenberg, Monika Graeser, Ronald Kates, Rachel Wuerstlein, Friedrich Feuerhake, Ulrike Nitz, Hans Kreipe, Nadia Harbeck, West German Study Group. Predictive value of HER2 expression, early response and tumor infiltrating lymphocytes (TILs) on efficacy of de-escalated pertuzumab+trastuzumab in the neoadjuvant WSG-ADAPT-HER2+/HR- trial [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-10-05.

ADAPTcycle: Adjuvant dynamic marker-adjusted personalized therapy comparing endocrine therapy plus ribociclib versus chemotherapy in intermediate-risk HR+/HER2- early breast cancer

TPS596

Background: WSG (West German Study Group)-ADAPTcycle is a prospective, multi-center, interventional, two-arm, open-label, controlled (neo)adjuvant, non-blinded, randomized phase III trial (EudraCT 2018-003749-40). It investigates whether HR+/HER2- intermediate-risk patients (pts) (about 20 % of HR+/HER2- early breast cancer, EBC) identified during screening (OncotypeDX and 3-week endocrine therapy (ET)) derive additional benefit from 2-years of the CDK4/6 inhibitor ribociclib plus ET compared to chemotherapy (CT) (followed by adjuvant ET). Co-primary endpoints are disease-free and distant disease-free survival. Methods: Starting Q1 2019 (enrollment 36 months, 80 sites), 5600 pts will be screened and 1670 randomized in a 3:2 ratio (1002 to ribociclib + ET; 668 to standard CT followed by ET). Pre-/postmenopausal pts with histologically confirmed invasive HR+/HER2- EBC at clinically enhanced risk (cT2-4 or Ki67 > 20 % or G3 or cN+) are eligible if they fulfill the ADAPT intermediate-risk group criteria: Recurrence Score (RS) ≤ 25 and poor endocrine response or RS > 25 and good endocrine response in p/cN0-1 pts or RS ≤ 25 with good endocrine response in c/pN2-3 pts. Endocrine responsiveness is determined by Ki67 response (drop to ≤ 10 %) after 3-week ET. Treatment duration is 2 years for the ribociclib + ET (premenopausal: AI + GnRH) arm and 16-24 weeks for the CT arm; treatment can be given in the neoadjuvant or adjuvant setting. 5-year follow-up consists of standard adjuvant ET. Patient reported outcomes (ePROs) are collected using CANKADO; ECG monitoring is performed using a novel CANKADO-based methodology. For translational analyses, tumor tissue will be collected at baseline (prior to ET), after 3-weeks ET (+/- 1w). Additional samples are required if residual tumor is diagnosed in case of neoadjuvant treatment and at time of recurrence. Exploratory tissue biomarker research will be conducted to assess alterations of molecular markers (e. g., ESR1, PIK3CA, CCND1, CDKN2A, RB1). Circulating DNA and tumor cells from blood samples will be used to assess mutations, gene expression, etc. Clinical trial information: 2018-003749-40.

Hybrid system calibration for multidimensional magnetic particle imaging

Magnetic particle imaging visualizes the spatial distribution of superparamagnetic nanoparticles. Because of its key features of excellent sensitivity, high temporal and spatial resolution and biocompatibility of the tracer material it can be used in multiple medical imaging applications. The common reconstruction technique for Lissajous-type trajectories uses a system matrix that has to be previously acquired in a time-consuming calibration scan, leading to long downtimes of the scanning device. In this work, the system matrix is determined by a hybrid approach. Using the hybrid system matrix for reconstruction, the calibration downtime of the scanning device can be neglected. Furthermore, the signal to noise ratio of the hybrid system matrix is much higher, since the size of the required nanoparticle sample can be chosen independently of the desired voxel size. As the signal to noise ratio influences the reconstruction process, the resulting images have better resolution and are less affected by artefacts. Additionally, a new approach is introduced to address the background signal in image reconstruction. The common technique of subtraction of the background signal is replaced by extending the system matrix with an entry that represents the background. It is shown that this approach reduces artefacts in the reconstructed images.

Prognostic impact of fascin-1 (FSCN1) in epithelial ovarian cancer

BACKGROUND

Fascin-1 (FSCN1) plays an important role in cancer development and is associated with invasion and metastasis. Therefore, we explored the expression and localization of FSCN1 in epithelial ovarian cancer (EOC).

MATERIALS AND METHODS

Expression analysis was performed by immunohistochemistry of paraffin-embedded tumor samples from 89 patients with EOC. Staining intensity and the percentage of positively stained tumor cells were used to calculate an immunoreactive score of 0-12 (IRS). These results were correlated to clinical and pathological characteristics as well as to patient survival.

RESULTS

Negative (IRS=0), weak (IRS=0-2) and strong (IRS>2) expression of FSCN1 in EOC was found in 5 (5.6%), 30 (33.7%) and 54 (60.7%) tumor samples, respectively. There was a strong correlation of residual postoperative tumor of >1 cm with higher immunoexpression of FSCN1 (p=0.04). Lower FSCN1 expression was associated with significantly poorer overall survival (p=0.02).

CONCLUSION

FSCN1 is frequently expressed in primary EOC. Its prognostic impact and function remains inconclusive and should be further examined in larger trials.

The risk of contralateral breast cancer in patients from BRCA1/2 negative high risk families as compared to patients from BRCA1 or BRCA2 positive families: a retrospective cohort study

Introduction

While it has been reported that the risk of contralateral breast cancer in patients from BRCA1 or BRCA2 positive families is elevated, little is known about contralateral breast cancer risk in patients from high risk families that tested negative for BRCA1/2 mutations.

Methods

A retrospective, multicenter cohort study was performed from 1996 to 2011 and comprised 6,235 women with unilateral breast cancer from 6,230 high risk families that had tested positive for BRCA1 (n = 1,154) or BRCA2 (n = 575) mutations or tested negative (n = 4,501). Cumulative contralateral breast cancer risks were calculated using the Kaplan-Meier product-limit method and were compared between groups using the log-rank test. Cox regression analysis was applied to assess the impact of the age at first breast cancer and the familial history stratified by mutation status.

Results

The cumulative risk of contralateral breast cancer 25 years after first breast cancer was 44.1% (95%CI, 37.6% to 50.6%) for patients from BRCA1 positive families, 33.5% (95%CI, 22.4% to 44.7%) for patients from BRCA2 positive families and 17.2% (95%CI, 14.5% to 19.9%) for patients from families that tested negative for BRCA1/2 mutations. Younger age at first breast cancer was associated with a higher risk of contralateral breast cancer. For women who had their first breast cancer before the age of 40 years, the cumulative risk of contralateral breast cancer after 25 years was 55.1% for BRCA1, 38.4% for BRCA2, and 28.4% for patients from BRCA1/2 negative families. If the first breast cancer was diagnosed at the age of 50 or later, 25-year cumulative risks were 21.6% for BRCA1, 15.5% for BRCA2, and 12.9% for BRCA1/2 negative families.

Conclusions

Contralateral breast cancer risk in patients from high risk families that tested negative for BRCA1/2 mutations is similar to the risk in patients with sporadic breast cancer. Thus, the mutation status should guide decision making for contralateral mastectomy.

A marker of homologous recombination predicts pathologic complete response to neoadjuvant chemotherapy in primary breast cancer

PURPOSE

To assess the prevalence of defective homologous recombination (HR)-based DNA repair in sporadic primary breast cancers, examine the clincopathologic features that correlate with defective HR and the relationship with neoadjuvant chemotherapy response.

EXPERIMENTAL DESIGN

We examined a cohort of 68 patients with sporadic primary breast cancer who received neoadjuvant anthracylcine-based chemotherapy, with core biopsies taken 24 hours after the first cycle of chemotherapy. We assessed RAD51 focus formation, a marker of HR competence, by immunofluorescence in postchemotherapy biopsies along with geminin as a marker of proliferative cells. We assessed the RAD51 score as the proportion of proliferative cells with RAD51 foci.

RESULTS

A low RAD51 score was present in 26% of cases (15/57, 95% CI: 15%-40%). Low RAD51 score correlated with high histologic grade (P = 0.031) and high baseline Ki67 (P = 0.005). Low RAD51 score was more frequent in triple-negative breast cancers than in ER- and/or HER2-positive breast cancer (67% vs. 19% respectively; P = 0.0036). Low RAD51 score was strongly predictive of pathologic complete response (pathCR) to chemotherapy, with 33% low RAD51 score cancers achieving pathCR compared with 3% of other cancers (P = 0.011).

CONCLUSIONS

Our results suggest that defective HR, as indicated by low RAD51 score, may be one of the factors that underlie sensitivity to anthracycline-based chemotherapy. Defective HR is frequent in triple-negative breast cancer, but it is also present in a subset of other subtypes, identifying breast cancers that may benefit from therapies that target defective HR such as PARP inhibitors.

The Value of Breast Ultrasound in BRCA1 and BRCA2 Mutation Carriers

OBJECTIVE: BRCA1/2 mutations carriers face a lifetime risk for breast cancer of 60 to 80%. Typically, tumor incidence is high at young age and tumor growth rates are significantly elevated. On ultrasound investigation the malignancies often mimic fibroadenomas with round shape, circumscribed margins and a homogeneous internal structure leading to a BIRADS 3 classification. On this background we evaluated the efficacy of ultrasound for the early detection of breast cancer in this high risk group.METHODS: Between 01/1997-07/2008 223 BRCA1/2 mutation carriers participated in a breast cancer screening program which included semi-annual ultrasound (US) and annual mammography (MG) and MR imaging (MRI).Screening procedures started from age 25, MG at age 30. As patients consecutively joint the study women underwent 5 (median) screening rounds with a range of 1 to 22 appointments, totaling 1855 rounds of screening. All three imaging modalities were coded according to the American College of Radiology (BI-RADS classification).RESULTS: We detected 15 primary and 14 secondary contralateral BRCA-associated tumors in 27 patients. Age at diagnosis ranged from 29 to 66 years (median 41 years). BI-RADS classification IV and V enabled the detection of 9 (32%) cancers by mammography, 21 (87,5%) by US and 27 (96%) by MRI scan. Specificity added up to 100%. Three (11%) tumors were detected by the semi-annual ultrasound screen and two patients presented with interval carcinomas (16 and 8 mm in diameter) between two screening appointments. Thus, the proportion of interval cancers was 7%.CONCLUSION: Semi-annual sonography as a supplementary examination enabled us to reveal 3 additional invasive cancers (two stage pT1b, one stage pT1c). Due to the specific tumor morphology and the considerably elevated tumor doubling time mutation carriers may benefit from the addition of semi-annual ultrasound as a highly sensitive and cost-effective method.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4004.