Palbociclib Rechallenge for Hormone Receptor-Positive/HER-Negative Advanced Breast Cancer: Findings from the Phase II BioPER Trial

PURPOSE

To assess the efficacy and exploratory biomarkers of continuing palbociclib plus endocrine therapy (ET) beyond progression on prior palbociclib-based regimen in patients with hormone receptor-positive/HER2-negative (HR+/HER2-) advanced breast cancer (ABC).

PATIENTS AND METHODS

The multicenter, open-label, phase II BioPER trial included women who had experienced a progressive disease (PD) after having achieved clinical benefit on the immediately prior palbociclib plus ET regimen. Palbociclib (125 mg, 100 mg, or 75 mg daily orally for 3 weeks and 1 week off as per prior palbociclib-based regimen) plus ET of physician's choice were administered in 4-week cycles until PD or unacceptable toxicity. Coprimary endpoints were clinical benefit rate (CBR) and percentage of tumors with baseline loss of retinoblastoma (Rb) protein expression. Additional endpoints included safety and biomarker analysis.

RESULTS

Among 33 patients enrolled, CBR was 34.4% [95% confidence interval (CI), 18.6-53.2; P < 0.001] and 13.0% of tumors (95% CI, 5.2-27.5) showed loss of Rb protein expression, meeting both coprimary endpoints. Median progression-free survival was 2.6 months (95% CI, 1.8-6.7). No new safety signals were reported. A signature that included baseline mediators of therapeutic resistance to palbociclib and ET (low Rb score, high cyclin E1 score, ESR1 mutation) was independently associated with shorter median progression-free survival (HR, 22.0; 95% CI, 1.71-282.9; P = 0.018).

CONCLUSIONS

Maintaining palbociclib after progression on prior palbociclib-based regimen seems to be a reasonable, investigational approach for selected patients. A composite biomarker signature predicts a subset of patients who may not derive a greater benefit from palbociclib rechallenge, warranting further validation in larger randomized controlled trials.

Role of germline variants in the metastasis of breast carcinomas

Most cancer-related deaths in breast cancer patients are associated with metastasis, a multistep, intricate process that requires the cooperation of tumour cells, tumour microenvironment and metastasis target tissues. It is accepted that metastasis does not depend on the tumour characteristics but the host’s genetic makeup. However, there has been limited success in determining the germline genetic variants that influence metastasis development, mainly because of the limitations of traditional genome-wide association studies to detect the relevant genetic polymorphisms underlying complex phenotypes. In this work, we leveraged the extreme discordant phenotypes approach and the epistasis networks to analyse the genotypes of 97 breast cancer patients. We found that the host’s genetic makeup facilitates metastases by the dysregulation of gene expression that can promote the dispersion of metastatic seeds and help establish the metastatic niche—providing a congenial soil for the metastatic seeds.

Abstract P2-07-08: Identification of UGT2B15 as a potential biomarker in response to neoadjuvant therapy in HER2+ breast cancer

INTRODUCTION. In response to neoadjuvant therapy, pathological complete response (pCR; lack of residual disease in breast and lymph nodes), has been proposed as a prognostic marker for long-term clinical outcomes, such as disease-free (DFS) and overall survival (OS), in human epidermal growth factor receptor 2 (HER2)-positive and triple-negative breast cancer. In clinical practice, recognizing those patients likely to achieve such responses proves challenging to the oncologist, making the identification of new useful biomarkers vital. Here, we searched for potential biomarkers that anticipate pCR to neoadjuvant therapy in HER2-positive, hormone receptor-negative breast cancer tissue samples. METHODS. Patients with early and locally advanced breast cancer, diagnose as HER2-positive, hormone receptor-negative by immunohistochemistry (IHC) at the time of neoadjuvant treatment were included. All samples were collected from biobank at Hospital Universitario Virgen del Rocio. We defined two groups: responder (R) and non-responder (nR) and analyzed 18 samples in the discovery cohort (10 R vs 8 nR) and 12 samples in the validation cohort (6 R vs 6 nR).The RNA for the study was extracted from tissue fixed in formaldehyde and paraffin embedded. The extraction of the RNA was carried out using the commercial kit RecoverAll Total Nucleic Acid Isolation Kit from Ambion (Applied Biosystems). RNA was quantified by Qubit RNA HS Assay Kit (Molecular Probes). Before hybridization, RNA for the discovery cohort was amplified using GeneChip WT Pico Kit (Applied Biosystems).We analyzed transcript expression using ClariomD array. Differential expression between the two groups was analyzed using in-house R scripts (version 3.5.1). Data were corrected and normalized using Robust Multi-array Average method. Expression was summarized at gene level using the corresponding annotation for ClariomD BrainArray. Gene validation was performed by qPCR using TaqMan Gene Expression Assay (Applied Biosystem). RESULTS. Considering a fold change ≥ 2 and an adjusted p-value &lt;0.05 as statistically significant, we found 53 differentially expressed transcripts: 51 downregulated transcripts (lower expression in R) and 2 upregulated transcripts (higher expression in R). The RNA was annotated as non-coding RNAs in over 25% of the cases. The distribution of such molecules was as followed: 8 long non-coding RNAs (56%); 3 non-coding RNAs (22%) and 3 pseudo-genes (22%). Regarding protein coding transcripts, gene ontology analysis revealed an enrichment of terms associated to metabolic processes and response to toxic substance.As expected, ERBB2, which encodes for HER2, appeared at the top of the list with a patent upregulation of expression in the responder group when compared with non-responder patients. To validate the data, we used qPCR and ERBB2 expression as a positive control of the results (p-value=0.0380). Our data showed a significant downregulation of UDP-glucuronosyltransferase 2B15 (UGT2B15; p-value= 0.0173), which encodes a glycosyltransferase, involved in the metabolism and elimination of toxic compounds. CONCLUSIONS. The ability to predict which patients will benefit from neoadjuvant therapy and achieve a pCR would allow for improved patient stratification and more personalized medicine. Here, we identified a set of transcript differentially expressed (FC&gt;2; adjusted p-value&lt;0.05) in patients that achieve pCR (R) when compared with tissue samples with residual disease (nR). We usedERBB2 expression as a positive control to validate the data and show that UGT2B15 is consistently upregulated in non-responder patients. Further work is needed to elucidate UGT2B15 role, but it is worth mentioning that an increased rate of glucuronidation has been associated with a loss of potency for the target drugs.

Citation Format: Ana Gil-Torralvo, Marta Benavent, Maria A Dominguez-Cejudo, Alejandro Falcon, Begoña Vieites, Sonia Molina-Pinela, Manuel Ruiz, Álvaro Montaño, Rosario Gónzalez, Julia Martínez, Juan de la Haba, Antonio Rodríguez, Maria I Queipo, Begoña Jímenez, Javier Salvador-Bofill. Identification of UGT2B15 as a potential biomarker in response to neoadjuvant therapy in HER2+ breast cancer [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 P2-07-08.

Abstract PD4-06: Trastuzumab deruxtecan in patients with HER2[+] or HER2-low-expressing advanced breast cancer and central nervous system involvement: Preliminary results from the DEBBRAH phase 2 study

Background: Approximately 30% to 40% of patients (pts) with HER2[+] advanced breast cancer (ABC) will develop brain metastases (BM) during the course of their disease. Trastuzumab deruxtecan (T-DXd; DS-8201) is an antibody-drug conjugate containing an anti-HER2 antibody, a cleavable tetrapeptide-based linker, and a topoisomerase I inhibitor payload. In the phase 2 DESTINY-Breast01 trial, T-DXd showed efficacy in the subgroup of HER2[+] ABC pts with stable BM at baseline. DEBBRAH is assessing the efficacy and safety of T-DXd in HER2[+] and HER2-low-expressing ABC pts with a history of BM and/or leptomeningeal carcinomatosis (LMC). Here, we report primary results from cohorts A and C. Methods: This is an ongoing, multicenter, open-label, 5-cohort, non-comparative, phase 2 study across 18 hospitals in 2 countries. A total of 39 pts aged ≥18 years with pretreated HER2[+] or HER2-low-expressing ABC with stable, progressing, or untreated BM and/or LMC are being enrolled in 5 cohorts: (A) HER2[+] ABC with non-progressing BM after radiotherapy and/or surgery; (B) HER2[+] or HER2-low-expressing ABC with asymptomatic untreated BM; (C) HER2[+] ABC with progressing BM after local treatment; (D) HER2-low-expressing ABC with progressing BM after local treatment; (E) HER2[+] or HER2-low-expressing ABC with LMC. In cohorts A and C, pts must have received prior taxane and ≥1 HER2-targeted therapy for ABC. Pts received 5.4 mg/kg T-DXd intravenously on day 1 of a 21-day cycle until disease progression, unacceptable toxicity, or consent withdrawal. The primary endpoint for cohort A is 16-week progression-free survival (PFS) per local assessment using RANO-BM for central nervous system (CNS) lesions and RECIST v.1.1 for extracranial lesions (H0: 5%); for cohort C, CNS overall response rate (ORR; H0: 10%). A single-arm binomial design is used for cohorts A and C. A futility interim analysis has been planned in cohort A after accrual of 4 pts. Sample size was planned to attain an 80% power at nominal level of one-sided α of 0.05 in each cohort. Results: Between Jun 29, 2020, and Feb 18, 2021, 26 pts were allocated in the study. Enrollment is complete in cohorts A (n=8 pts) and C (n=9 pts), and ongoing in the remaining cohorts. At data cutoff (May 21, 2021), median follow-up for the cohort A was 5.5 months (IQR 4.4-6.9) and 6.2 months (IQR 5.1-6.4) for the cohort C. In the cohort A, 6 (75.0%) of 8 pts were alive without disease progression at 16 weeks, reaching the primary endpoint (p&lt;0.01). In the cohort C, the CNS ORR was 55.6% (5 pts with partial response), also meeting the primary endpoint (p&lt;0.01). At the time of this analysis, 75.0% of pts of the cohort A and 55.6% of the cohort C remained on therapy. The most frequent adverse events of any grade in 26 pts who received at least 1 dose of T-DXd were fatigue (11 [42.3%]; 3.8% of grade 3), nausea (10 [38.5%]), a decreased neutrophil count (9 [34.6%]; 11.5% of grade 3), and anemia (6 [23.1%]). Treatment-related serious adverse events occurred in 1 (3.8%) of 26 pts due to grade 1 pneumonitis. No treatment-related deaths were reported. Conclusions: T-DXd demonstrated preliminary efficacy with manageable toxicity in pretreated pts with HER2[+] ABC with stable and progressing BM after local treatment. Further investigation is required in larger cohorts to validate these findings. The assessment of the T-DXd antitumor activity in cohorts B, D, and E is currently ongoing.

Citation Format: Marta Vaz Batista, Patricia Cortez, Manuel Ruiz, Juan Miguel Cejalvo, Juan de la Haba, Laia Garrigós, Fabricio Racca, Sonia Servitja, Salvador Blanch, Iris Teruel, José Manuel Pérez-García, María Gion, Monica Nave, Antonio Llombart-Cussac, Miguel Sampayo-Cordero, Andrea Malfettone, Javier Cortes, Sofia Braga. Trastuzumab deruxtecan in patients with HER2[+] or HER2-low-expressing advanced breast cancer and central nervous system involvement: Preliminary results from the DEBBRAH phase 2 study [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 PD4-06.

Abstract PS10-27: A phase II proof-of-concept study of palbociclib (P) rechallenge in patients (pts) with hormone receptor (HR)[+]/HER2[-] metastatic breast cancer (MBC) and clinical benefit to prior P-based treatment (BIOPER)

Background: The addition of a cyclin-dependent kinase 4-6 inhibitor (CDK4/6i) to letrozole or fulvestrant significantly improves progression-free survival (PFS) and overall survival (OS) in HR[+]/HER2[-] MBC pts. At present, the optimal endocrine treatment (ET) after progression on a CDK4/6i remains unknown. However, preliminary findings revealed drivers of adaptive resistance more frequently related to ET than to CDK4/6i. BIOPER explored the efficacy and safety of continuing the same CDK4/6i in combination with a different ET agent beyond progression on prior P-based regimen in HR[+]/HER2[-] MBC and assessed predictive biomarkers to identify those pts who are more likely to benefit from this strategy. Methods: BIOPER (NCT03184090) is a multicenter, non-controlled, phase II trial. Eligible pts included pre- and post-menopausal women aged ≥18 years with HR[+]/HER2[-] MBC that showed a confirmed progressive disease (PD) after having achieved clinical benefit (response or stable disease ≥24 weeks) on immediately prior P plus ET-based regimen. Up to two prior ET lines and not more than one line of prior chemotherapy for MBC were allowed. Pts received P (oral, 75/100/125 mg/day 3 weeks on/1 week off) combined with ET of physician’s choice (including tamoxifen, exemestane, fulvestrant, anastrozole, or letrozole) until PD or unacceptable toxicity. Co-primary endpoints were clinical benefit rate (CBR) -in terms of complete or partial response [PR] and stable disease lasting ≥24 weeks as per RECIST 1.1 (H0: CBR≤5% versus H1: CBR≥20%)- and tumor molecular alterations in the cyclin D-CDK 4/6-retinoblastoma pathway detected at baseline as markers of resistance and sensitivity to P rechallenge. Secondary endpoints included investigator-assessed PFS, objective response rate (ORR), OS, and safety using the Common Terminology Criteria for Adverse Events (AEs) 4.03. Results: Between June 15, 2017 and April 25, 2019, a total of 33 pts from 21 centers in 2 countries were enrolled. Among the 33 pts who were included in the safety set, 1 patient who did not achieve clinical benefit on prior P-based regimen was excluded from the efficacy analysis (n=32). The median age was 59.5 years (range 42-80 years) and all pts were post-menopausal. A total of 25 (78.1%) pts had visceral disease (56.3% of whom with liver metastases), 16 (50%) had ECOG 0, and 19 (59.4%) presented ≥3 metastatic sites. Of 32 pts, 15 (46.9%) received letrozole, 14 (43.8%) received fulvestrant, and 3 (9.4%) exemestane. The median PFS for the prior P-based regimen was 13.8 months (mo) (95% confidence interval [CI] 5.6-47.1 mo). The median number of prior ET and chemotherapy lines for MBC was 2 (range 1-4). By the data cutoff date, 26 PFS events occurred, 5 pts were still on treatment, and 1 patient discontinued treatment because of investigator’s decision. The CBR was 34.4% (95% CI 18.6-53.2%) reaching the prespecified primary endpoint. The ORR was 3.1% (95% CI 0.1-16.2%) with 1 patient with PR. The median PFS was 2.6 mo (95% CI 1.8-5.5 mo). With a median follow-up of 11.8 mo, the OS data were immature with a total of 8 deaths (25%). The incidence of all grade (G) and G 3 or 4 (G3-4) AEs were 90.9% and 48.5%, respectively. The most common G3-4 AEs were neutropenia (42.4%) and leukopenia (6.1%). No discontinuations due to AEs and treatment-related deaths occurred. A comprehensive molecular tumor profiling will be presented during the symposium. Conclusions: Prolonging CDK4/6 blockade beyond progression on prior P-based treatment achieved the prespecified clinical benefit among pts with HR[+]/HER2[-] MBC. This strategy is currently being evaluated in the randomized phase II PALMIRA trial. Further research is ongoing to identify patient subgroups who could benefit from this treatment strategy.

Citation Format: Antonio Llombart-Cussac, Javier Cortés, Beatriz Bellosillo Paricio, Miguel Gil Gil, Giuseppe Curigliano, José Manuel Pérez-García, Laura Comerma Blesa, Manuel Ruíz Borrego, Enrique Espinosa, Lourdes Calvo, Begoña Bermejo, Meritxell Bellet, Federico Rojo Todo, Juan de la Haba, Vanesa Quiroga, Alessandro Minisini, Ana Santaballa, Miguel Sampayo, Andrea Malfettone, Joan Albanell. A phase II proof-of-concept study of palbociclib (P) rechallenge in patients (pts) with hormone receptor (HR)[+]/HER2[-] metastatic breast cancer (MBC) and clinical benefit to prior P-based treatment (BIOPER) [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 PS10-27.

Abstract P4-10-28: Identification of a specific epigenetic signature in patients showing secondary hypertension upon anti-VEGF treatment from the GEICAM/2011-04 (BRECOL) study

BACKGROUND The appearance of secondary hypertension (HTN) is one of the most common side effects of anti-angiogenic agents since it emerges in over 50% of the patients with these therapies. Independently of tumor type, in most clinical trials it was possible to observe a positive association between secondary HTN and better clinical outcome, including Progression Free Survival (PFS) and Overall Survival (OS). Preeclampsia is one of the biological models that better resembles the anti-VEGF/VEGFR action of these therapies. DNA methylation is one of the epigenetic mechanisms potentially related to variation in susceptibility to gestational HTN. The objective of our study is to define a specific epigenetic signature that could predict secondary HTN to anti-angiogenic treatment in patients that received bevacizumab in combination with chemotherapy (CT) from the BRECOL study. METHODS Patients (n=113) from BRECOL study (NCT01733628) received bevacizumab in combination with oxaliplatin or irinotecan + fluoropyrimidines for metastatic colorectal cancer (n=49), and with paclitaxel or capecitabine for metastatic breast cancer (n=64). Blood pressure (BP) was recorded with a Holter measurement (24 hours registration starting 2 hours after treatment administration). A methylation analysis was carried out on DNA obtained from pretreatment peripheral blood samples in 32 patients (28%) distributed in 4 experimental groups (8 patients / each) and classified according to their HTN history and to their BP variation upon bevacizumab plus CT: • Group A: patients with HTN history and with BP increase • Group B: patients with HTN history and with no BP increase • Group C: patients without HTN history and with BP increase • Group D: patients without HTN history and with no BP increase Analysis was realized with the “Infinium Human Methylation EPIC BeadChip” array (Illumina®) on bisulfite-converted DNA and differentially methylated sites were identified with the LIMMA (“Linear Models for Microarray Analysis”) bioinformatics tool (Bioconductor®). RESULTS Upon analysis of 850000 different methylation sites distributed all over the genome, we identified 27 (18 localized in the coding regions of the genes: FMNL2, METTL3, ACOT6, SCARNA20, PREX1, DNAI2, RAET1G, KCNJ8, GDF7, SYNPO2, CUGBP1, FRMD8, MKL2, HIF1A, TMEM177, UTP23, PXK and TNPO1; 9 localized in intergenic regions) that are differentially methylated in patients that showed secondary HTN to bevacizumab plus CT, independently of HTN history (Groups A + C vs. B + D). Based on Principal Components (PC) analysis, we defined a methylation score predictive of elevated BP. First PC (PC1) explains the 83.2% of the variability of the 27 identified methylation sites and allows to distinguish between patients that do and do not show secondary HTN. CONCLUSIONS High BP upon anti-angiogenic treatment is associated to specific DNA methylation profiles. We identified an epigenetic methylation signature putative predictive of secondary HTN to bevacizumab treatment in metastatic breast and colorectal cancer.

Citation Format: Juan de la Haba, Teresa Morales-Ruiz, Pilar García-Alfonso, Jose Ponce Lorenzo, Lourdes Calvo, Antonio Antón, Raul Marquez, Pedro Sánchez-Rovira, Ana Santaballa, Eva Ciruelos, María Victoria García-Ortiz, Teresa Roldán-Arjona, Jesús Herranz, Massimo Chiesa, Rosalía Caballero, Javier Gallego, Álvaro Rodríguez-Lescure. Identification of a specific epigenetic signature in patients showing secondary hypertension upon anti-VEGF treatment from the GEICAM/2011-04 (BRECOL) study [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 P4-10-28.

Survival impact of primary tumor resection in de novo metastatic breast cancer patients (GEICAM/El Alamo Registry)

The debate about surgical resection of primary tumor (PT) in de novo metastatic breast cancer (MBC) patients persists. We explored this approach's outcomes in patients included in a retrospective registry, named El Álamo, of breast cancer patients diagnosed in Spain (1990-2001). In this analysis we only included de novo MBC patients, 1415 of whom met the study's criteria. Descriptive, Kaplan-Meier and Cox regression analyses were carried out. Median age was 63.1 years, 49.2% of patients had single-organ metastasis (skin/soft tissue [16.3%], bone [33.8%], or viscera [48.3%]). PT surgery (S) was performed in 44.5% of the cases. S-group patients were younger, had smaller tumors, higher prevalence of bone and oligometastatic disease, and lower prevalence of visceral involvement. With a median follow-up of 23.3 months, overall survival (OS) was 39.6 versus 22.4 months (HR = 0.59, p < 0.0001) in the S- and non-S groups, respectively. The S-group OS benefit remained statistically and clinically significant regardless of metastatic location, histological type, histological grade, hormone receptor status and tumor size. PT surgery (versus no surgery) was associated with an OS benefit suggesting that loco-regional PT control may be considered in selected MBC patients. Data from randomized controlled trials are of utmost importance to confirm these results.

Phase III Trial of Adjuvant Capecitabine After Standard Neo-/Adjuvant Chemotherapy in Patients With Early Triple-Negative Breast Cancer (GEICAM/2003-11_CIBOMA/2004-01)

PURPOSE

Operable triple-negative breast cancers (TNBCs) have a higher risk of relapse than non-TNBCs with standard therapy. The GEICAM/2003-11_CIBOMA/2004-01 trial explored extended adjuvant capecitabine after completion of standard chemotherapy in patients with early TNBC.

PATIENTS AND METHODS

Eligible patients were those with operable, node-positive—or node negative with tumor 1 cm or greater—TNBC, with prior anthracycline- and/or taxane-containing chemotherapy. After central confirmation of TNBC status by immunohistochemistry, patients were randomly assigned to either capecitabine or observation. Stratification factors included institution, prior taxane-based therapy, involved axillary lymph nodes, and centrally determined phenotype (basal v nonbasal, according to cytokeratins 5/6 and/or epidermal growth factor receptor positivity by immunohistochemistry). The primary objective was to compare disease-free survival (DFS) between both arms.

RESULTS

Eight hundred seventy-six patients were randomly assigned to capecitabine (n = 448) or observation (n = 428). Median age was 49 years, 55.9% were lymph node negative, 73.9% had a basal phenotype, and 67.5% received previous anthracyclines plus taxanes. Median length of follow-up was 7.3 years. DFS was not significantly prolonged with capecitabine versus observation [hazard ratio (HR), 0.82; 95% CI, 0.63 to 1.06; P = .136]. In a preplanned subgroup analysis, nonbasal patients seemed to derive benefit from the addition of capecitabine with a DFS HR of 0.53 versus 0.94 in those with basal phenotype (interaction test P = .0694) and an HR for overall survival of 0.42 versus 1.23 in basal phenotype (interaction test P = .0052). Tolerance of capecitabine was as expected, with 75.2% of patients completing the planned 8 cycles.

CONCLUSION

This study failed to show a statistically significant increase in DFS by adding extended capecitabine to standard chemotherapy in patients with early TNBC. In a preplanned subset analysis, patients with nonbasal phenotype seemed to obtain benefit with capecitabine, although this will require additional validation.

Abstract CT219: Neoadjuvant letrozole and palbociclib in stage II-IIIB HR[+]/HER2[-] breast cancer with Oncotype DX Recurrence Score® (RS) 18-25 or 26-100. Analysis of RS changes at surgery (DxCARTES trial)

BACKGROUND: The combination of a CDK4/6 inhibitor (palbociclib, abemaciclib, or ribociclib) with an aromatase inhibitor (AI) significantly reduces Ki67 compared to single-agent AI in the neoadjuvant setting, but the rates of pathological complete response (pCR) or residual cancer burden (RCB) 0-I remain modest. Despite this inadequate pathological downstaging, to date, there is no data about the efficacy of this treatment in terms of molecular downstaging detected by a more refined genomic signature than Ki67, such as the Oncotype DX Breast Recurrence Score® (RS) test. The aim of this trial is to validate the ability of neoadjuvant palbociclib plus letrozole to modify two initial intermediate or high RS tumor cohorts.

TRIAL DESIGN: This is an international, multicenter, open-label, non-comparative, phase II trial. Main selection criteria include: (1) Pre- or post-menopausal women with treatment-naïve, centrally assessed, HR-positive/HER2-negative, Ki67 ≥ 20%, and stage II-IIIB breast cancer; (2) Pre-treatment RS result ≥ 18; (3) Patients agree to collect tissue samples at screening, at Cycle 1 Day 14 of treatment, and at surgery. Patients will be allocated, according to the pre-treatment RS result, either to Cohort A (RS 18-25) or Cohort B (RS 26-100) and will receive treatment with palbociclib (125 mg QD, 3/1 schedule) in combination with letrozole (2.5 mg QD, every 28-day cycle), ± LHRH analogs if pre-menopausal status, for 24 weeks. Definitive breast surgery will be performed within 7 days after completion of 6 treatment cycles. The primary objective of the study is to explore the ability of palbociclib in combination with letrozole to induce global molecular changes, measured by either the post-treatment RS result at surgery, or pCR. Secondary objectives include: (1) Concordance rate among post-treatment RS result and RCB, Ki67, and preoperative endocrine prognostic index (PEPI) score; (2) Overall response rate; (3) Safety-related outcome as per Common Terminology Criteria for Adverse Events v. 5.0. Patients will be accrued in a Simon’s two-stage design trial: optimal design in Cohort A and minimax design in Cohort B. With a unilateral type one error (alpha) set at 0.025 and a 0.8 power (type two error beta = 0.2), the required number of evaluable patients are 28. Considering a drop-out rate no lower than 10%, a sample size of 33 patients in each cohort will be needed. First Patient First Visit: Expected on April 2019.

Citation Format: Antonio Llombart Cussac, José Pérez-García, Ángel Guerrero, Begoña Bermejo, Miguel Gil, Vicente Carañana, Serafín Morales, Juan de la Haba, María Fernández, Emilio Alba, Ander Urruticoechea, Lourdes Calvo, Mireia Margeli, Antonio Antón, Manuel Ruíz Borrego, Joan Albanell, Pedro Sánchez Rovira, Meritxell Bellet, Sofia Braga, Passos Coelho, Miguel Abreu, Javier Cortés. Neoadjuvant letrozole and palbociclib in stage II-IIIB HR[+]/HER2[-] breast cancer with Oncotype DX Recurrence Score® (RS) 18-25 or 26-100. Analysis of RS changes at surgery (DxCARTES trial) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT219.

Triple negative breast cancer subtypes and pathologic complete response rate to neoadjuvant chemotherapy

Triple negative breast cancer (TNBC) is a heterogeneous disease with distinct molecular subtypes that differentially respond to chemotherapy and targeted agents. The purpose of this study is to explore the clinical relevance of Lehmann TNBC subtypes by identifying any differences in response to neoadjuvant chemotherapy among them. We determined Lehmann subtypes by gene expression profiling in paraffined pre-treatment tumor biopsies from 125 TNBC patients treated with neoadjuvant anthracyclines and/or taxanes +/- carboplatin. We explored the clinicopathological characteristics of Lehmann subtypes and their association with the pathologic complete response (pCR) to different treatments. The global pCR rate was 37%, and it was unevenly distributed within Lehmann’s subtypes. Basal-like 1 (BL1) tumors exhibited the highest pCR to carboplatin containing regimens (80% vs 23%, p=0.027) and were the most proliferative (Ki-67>50% of 88.2% vs. 63.7%, p=0.02). Luminal-androgen receptor (LAR) patients achieved the lowest pCR to all treatments (14.3% vs 42.7%, p=0.045 when excluding mesenchymal stem-like (MSL) samples) and were the group with the lowest proliferation (Ki-67≤50% of 71% vs 27%, p=0.002). In our cohort, only tumors with LAR phenotype presented non-basal-like intrinsic subtypes (HER2-enriched and luminal A). TNBC patients present tumors with a high genetic diversity ranging from highly proliferative tumors, likely responsive to platinum-based therapies, to a subset of chemoresistant tumors with low proliferation and luminal characteristics.

Limitations in predicting PAM50 intrinsic subtype and risk of relapse score with Ki67 in estrogen receptor-positive HER2-negative breast cancer

PAM50/Prosigna gene expression-based assay identifies three categorical risk of relapse groups (ROR-low, ROR-intermediate and ROR-high) in post-menopausal patients with estrogen receptor estrogen receptor-positive (ER+)/ HER2-negative (HER2-) early breast cancer. Low risk patients might not need adjuvant chemotherapy since their risk of distant relapse at 10-years is below 10% with endocrine therapy only. In this study, 517 consecutive patients with ER+/HER2- and node-negative disease were evaluated for Ki67 and Prosigna. Most of Luminal A tumors (65.6%) and ROR-low tumors (70.9%) had low Ki67 values (0-10%); however, the percentage of patients with ROR-medium or ROR-high disease within the Ki67 0-10% group was 42.7% (with tumor sizes ≤2 cm) and 33.9% (with tumor sizes > 2 cm). Finally, we found that the optimal Ki67 cutoff for identifying Luminal A or ROR-low tumors was 14%. Ki67 as a surrogate biomarker in identifying Prosigna low-risk outcome patients or Luminal A disease in the clinical setting is unreliable. In the absence of a well-validated prognostic gene expression-based assay, the optimal Ki67 cutoff for identifying low-risk outcome patients or Luminal A disease remains at 14%.

Nab-Paclitaxel in Metastatic Breast Cancer: Defining the Best Patient Profile

Around 40% of patients with breast cancer will present with a recurrence of the disease. Chemotherapy is recommended for patients with recurrent hormone-independent or hormone-refractory breast cancer and almost all patients with metastatic breast cancer (MBC) receive chemotherapy during their medical history. Nanoparticle albuminbound (nab)-paclitaxel is a solvent-free, 130-nanometer particle formulation of paclitaxel. Nab-paclitaxel can be administered to all patients for whom the treatment choice is a taxane. In this review, 6 patient profiles for which nabpaclitaxel may be particularly useful are described and analyzed: (i) as first-line treatment of MBC, (ii) as second-line treatment of MBC after oral chemotherapy, (iii) after a standard taxane, (iv) as third-line treatment after a standard taxane and oral chemotherapy, (v) for patients with HER2-positive MBC and (vi) for patients with intolerance to standard taxanes. Nab-paclitaxel is a rational treatment choice for patients with MBC in different settings, as well as for those with prior exposure to a standard taxane.

Abstract P5-19-21: TRASTYVERE study: A retrospective analysis of HER2-positive metastatic breast cancer (MBC) patients treated in Spain with lapatinib (L) plus trastuzumab (T)

Background: Vertical dual blockade with L and T in heavily pretreated HER2+ MBC patients has shown consistent survival gain in a phase III trial (Blackwell KL et al. 2012), justifying an EMA approval for the hormone-negative subgroup. However, there is very limited information about the futility of the combination in clinical practice, mostly in patients progressing also on prior L regimens.

Methods: We conducted a retrospective analysis among patients treated in Spain by compassionate uses for the combination of T-L. The study was approved by the regulatory authorities and ethics committees from the 14 participating centers. Major inclusion criteria were (1) HER2+ MBC; (2) progression on at least one prior line of T for advanced disease; and (3) T-L treatment started between JAN/2005 and DEC/2012. Concomitant endocrine therapy for HR+ patients as well as prior exposure to L was allowed. Chemotherapy combinations were excluded. A total of 111 patients were predefined for the primary outcome: clinical benefit rate (CBR). Secondary endpoints included time to progression (TTP), overall survival (OS) and toxicity. 114 women were included and externally monitored.

Results: The median age was 60 years (34 - 89); 64% HR+; 77% visceral disease; 32% CNS disease (37 patients); 47% with ≥3 organs involved. Mean number of prior T lines 4 (range 0-13); 64% previously treated with L. A total of 40 patients (35%) achieved a CBR (95%CI 26–44%); 6 CR, 19 PR and 15 SD lasting &gt;24 weeks. The median time to progression was 3.8 months (95%CI 3.3–5.1) and the median overall survival 21.6 months (95%CI 17.1–27.3). CBR, median TTP and median OS achieved in patients with CNS disease were 32.4% (95%CI 17.3–47.5%), 3.6 (95%CI 2.8–5.9) and 15.4 (95%CI 10.9–27.3) months, respectively.

The CBR was independent of L treatment (41.5% L naïve vs. 31.5% L pretreated, p=0.285) and HR status (39% HR- vs. 32.9% HR+, p=0.509). Patients with &lt;3 metastatic sites showed higher CBR than patients with ≥3 (45 vs. 24.1%, respectively, p=0.019). No significant trends were observed in any pre-specified condition for TTP and OS. Grade 3/4 toxicities were reported in 20 patients (17.5%). Only 2 patients report asymptomatic cardiac toxicities.

Conclusions: The combination of T-L seems safe and active in heavily pretreated patients. The combination remains active among patients progressing on prior L. Future research may focus on the ability of endocrine therapy to increase activity among HER2+/HR+ patients.

REFERENCES:

1 Blackwell KL, Burstein HJ, Storniolo AM, et al: Overall survival benefit with lapatinib in combination with trastuzumab for patients with human epidermal growth factor receptor 2-positive metastatic breast cancer: final results from the EGF104900 Study. J Clin Oncol 2012;30(21):2585-2592.

Citation Format: Joaquin Gavilá, Begoña Bermejo, Álvaro Rodríguez-Lescure, Juan Lao Romera, Luis Manso, Joan Brunet, Eva Muñoz, Marta Santisteban, César A Rodríguez, Ana Santaballa, Juan de la Haba, Pedro Sánchez-Rovira, Manuel Ruiz-Borrego, Jose Ángel García-Saenz, Javier Cortés, Antonio Llombart. TRASTYVERE study: A retrospective analysis of HER2-positive metastatic breast cancer (MBC) patients treated in Spain with lapatinib (L) plus trastuzumab (T) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-19-21.

Abstract OT1-1-05: Phase III study of palbociclib in combination with exemestane vs. capecitabine, in hormonal receptor (HR) positive/HER2 negative metastatic breast cancer (MBC) patients with resistance to non-steroidal aromatase inhibitors (NSAI): PEARL study (GEICAM/2013-02_CECOG/BC.1.3.006)

Background: Endocrine therapy (ET) is the cornerstone treatment for HR–positive, HER2-negative breast cancer (BC) patients. AIs have become the treatment of choice in postmenopausal patients. The high response rates with ET in these patients are partially undermined by the resistance developed by most of them over time. On early disease recurrence/progression to AIs, the treatment options include other AI, estrogen-receptor antagonists or chemotherapy (being capecitabine one of the best options). Preclinical data suggest that ER+/HER2- BC are dependent on cyclin-dependent kinases 4/6 (CDK4/6) function; the inhibition of this target may be effective in delaying/reverting endocrine resistance. Palbociclib is an oral novel CDK4/6 inhibitor that seems to be synergistic with ET in preclinical and clinical studies.

Trial Design: This is an international (6 countries) randomized phase III study. Patients are randomized 1:1 to exemestane (25 mg daily) plus palbociclib (125 mg daily x3 weeks every 4 weeks) vs. capecitabine (1,250 mg/m2 twice daily x2 weeks every 3 weeks). Postmenopausal patients with HR+/HER2- MBC are eligible if resistant to previous NSAI (letrozole or anastrozole) defined as: recurrence while on or within 12 months after the end of adjuvant treatment or progression while on or within 1 month after the end of treatment for MBC. Previous chemotherapy is permitted either in the (neo)adjuvant setting and/or as first line for MBC. Patients must have measurable disease according to RECIST 1.1 or lytic bone lesions in the absence of measurable disease. The primary objective is Progression-Free Survival (PFS); secondary objectives are overall survival, response rate, clinical benefit rate, response duration, safety, quality of life and biomarker’s defined changes. The study will recruit 348 patients to detect a difference of 2.75 months in the median PFS (from 6 to 8.75 months; hazard ratio= 0.686), with a power of 80% and a 5% two sided significance level. The study started recruitment in March 2014 and 14 patients have been included so far (ClinTrials.gov reference NCT02028507).

Citation Format: Miguel Martín, Semir Beslija, Eva Carrasco, Zsuzanna Kahan, Ma José Escudero, Istvan Lang, Begoña Bermejo, Moshe Inbar, José Ignacio Chacón, Dan Jinga, José Ángel García-Saenz, Juan de la Haba, Serafín Morales, Miguel Gil, Laura Murillo, Antonio Antón, Manuel Ruiz-Borrego, Christoph Zielinski, Günther Steger, Bella Nisenbaum. Phase III study of palbociclib in combination with exemestane vs. capecitabine, in hormonal receptor (HR) positive/HER2 negative metastatic breast cancer (MBC) patients with resistance to non-steroidal aromatase inhibitors (NSAI): PEARL study (GEICAM/2013-02_CECOG/BC.1.3.006) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr OT1-1-05.

Practical prognostic index for patients with metastatic recurrent breast cancer: retrospective analysis of 2,322 patients from the GEICAM Spanish El Alamo Register

Women with recurrent metastatic breast cancer from a Spanish hospital registry (El Alamo, GEICAM) were analyzed in order to identify the most helpful prognostic factors to predict survival and to ultimately construct a practical prognostic index. The inclusion criteria covered women patients diagnosed with operable invasive breast cancer who had metastatic recurrence between 1990 and 1997 in GEICAM hospitals. Patients with stage IV breast cancer at initial diagnosis or with isolated loco-regional recurrence were excluded from this analysis. Data from 2,322 patients with recurrent breast cancer after primary treatment (surgery, radiation and systemic adjuvant treatment) were used to construct the prognostic index. The prognostic index score for each individual patient was calculated by totalling up the scores of each independent variable. The maximum score obtainable was 26.1. Nine-hundred and sixty-two patients who had complete data for all the variables were used in the computation of the prognostic index score. We were able to stratify them into three prognostic groups based on the prognostic index score: 322 patients in the good risk group (score < or =13.5), 308 patients in the intermediate risk group (score 13.51-15.60) and 332 patients in the poor risk group (score > or =15.61). The median survivals for these groups were 3.69, 2.27 and 1.02 years, respectively (P < 0.0001). In conclusion, risk scores are extraordinarily valuable tools, highly recommendable in the clinical practice.

A phase II study of weekly vinorelbine and trastuzumab in patients with HER2-positive metastatic breast cancer

BACKGROUND

Trastuzumab combined with cytotoxic agents presents encouraging results in metastatic breast cancer (MBC), but cardiac toxicity limits some combinations. The synergism shown with trastuzumab and the favorable tolerability profile of vinorelbine provided the rationale for investigating this combination.

PATIENTS AND METHODS

Patients with HER2-positive MBC who had received <2 lines of chemotherapy for metastatic disease were included. Vinorelbine (25 mg/m2 on day 2, then weekly on day 1) and trastuzumab (4 mg/kg on day 1, then 2 mg/kg weekly) were administered for a maximum of 6 cycles (1 cycle=3 weeks).

RESULTS

A total of 52 patients were enrolled. The median age was 50 years (range, 26-79 years). Ninety percent of the patients had received adjuvant chemotherapy, 42% received a first line of chemotherapy for MBC, and 69% had disease at visceral sites. The overall response rate was 58% (95% CI, 43%-71%). The median time to progression and overall survival were 7 months (95% CI, 5-9 months) and 26 months (95% CI, 20-32 months), respectively. Grade 4 neutropenia was present in 3 courses; neutropenic fever was not reported. The main grade 3 nonhematologic toxicities were asthenia, neuropathy, diarrhea, alopecia, and nausea/vomiting. No patients experienced serious cardiac toxicity.

CONCLUSION

These results confirm that weekly vinorelbine/trastuzumab is an active and safe regimen in patients with HER2-positive MBC with an unfavorable prognosis.