Abstract OT2-10-04: Treatment of advanced or metastatic triple-negative breast cancer with adoptive therapy of PD1+ tumor-infiltrating lymphocytes (TILS001 trial)

Background Metastatic triple-negative breast cancer (mTNBC) exhibits a particularly poor clinical outcome, generally with rapid progression and worse overall survival (OS) than other BC subtypes. Among the few therapeutic options, chemotherapy-based combinations are associated with increased toxicity and limited survival benefit, being treatment with sequential single agents, such as paclitaxel considered an appropriate first-line regimen for the metastatic setting for PDL-1 negative patients. Herein, there is an urgent need for clinically active agents for the mTNBC. Adoptive cell transfer (ACT)-based immunotherapy using ex vivo activated and expanded tumor-infiltrating lymphocytes (TILs) has shown promising therapeutic outcomes in some patients with metastatic tumors. The identification, selection, and enrichment of tumor-reactive lymphocytes at the early stages of the ACT generation could enhance their clinical activity. Thus, the selection of reactive T cells, such as PD1-positive (PD1+) TILs, could improve the responses achieved in those settings. TILS001 trial aims to explore the safety, tolerability and efficacy of selected PD1+ T-cell infusion with a previous pre-selection of mRNA PD1-high expression in patients with mTNBC. Study design: TILs001 trial is an open-label, single-arm, multicenter phase I/II prospective study with a two-stage design evaluating treatment with PD1+ TILs infusion in advanced or mTNBC, defined as HER2 negative and Hormonal Receptor < 10%. The study involves three different parts before PD1+TILs treatment. Tumor samples evaluable for PD1 mRNA expression and life expectancy ≥6 months are mandatory for part 1. Patients with high levels of PD1 mRNA, defined by the pre-specified cutoff, candidates for receiving a first-line taxane-based containing regimen and with at least 1 accessible target lesion to generate TILs are eligible for part 2. Finally, once the complete expansion of PD1+TILs is reached, patients will receive the non-myeloablative lymphodepleting chemotherapy regimen followed by PD1+TIL infusion and IL-2 treatment. Allogeneic hematopoietic stem cell transplantation, immune system-related disease or clinically active cerebral metastasis are not allowed. The primary objectives are to evaluate the safety and tolerability of the PD1+ TIL product, as per incidence of grade 3-5 adverse events (AE) or any grade AE that leads to treatment discontinuation and to assess the efficacy of ACT therapy with selected PD1+ TILs in mTNBC in terms of progression-free survival (PFS) at 6 months. The secondary endpoints are clinical benefit rate at 6 months (CBR6), overall response rate, duration of response (DoR), PFS and OS. Further translational research including immunophenotyping, TCR sequencing and mutational analysis will also be performed. The first 3 patients will be included in a safety run-in phase where safety will be evaluated 24h after PD1+/TILs infusion (before IL-2 treatment) and a phase II stage where efficacy will be evaluated, which will include up to 20 patients. Patients will be enrolled in 4 sites in Spain. Recruitment is expected to start by July 2022 and to be completed within 24 months. This study is financially supported by the Asociación Española Contra el Cáncer (GCAEC19010PRAT). NCT05451784

Citation Format: Nuria Chic, Eva Ciruelos, Cristina Saura, Europa-Azucena Gonzalez, Luís Álvarez-Vallina, Juan José Lasarte, Alena Gros, Lorea Villanueva, Jordi Canes, Laura Angelats, Aleix Prat, Tomás Pascual, Marta Santisteban, Manel Juan. Treatment of advanced or metastatic triple-negative breast cancer with adoptive therapy of PD1+ tumor-infiltrating lymphocytes (TILS001 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 OT2-10-04.

Abstract P5-02-44: Efficacy analysis of CDK4/6 inhibitors in combination with endocrine therapy treatment in HR+/HER2- breast cancer according to PAM50 intrinsic subtype: primary results of SOLTI-1801_CDK-PREDICT study

Background: First-line treatment with cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) plus endocrine therapy (ET) has demonstrated efficacy in improving progression-free survival (PFS), overall response rate (ORR) and, more recently, ribociclib was also improve overall survival (OS) in hormone receptor-positive/HER2-negative (HR+/HER2-) advanced breast cancer (aBC). Unfortunately, most patients eventually progress and develop secondary or primary endocrine resistance. To date, no clinical or molecular markers have shown clinical utility in this setting. However, data from retrospective analysis suggest that intrinsic subtypes (IS) are prognostic and predict benefit from CDK4/6i+ET (Finn SABCS 2017, Prat. JCO 2021). Here, we have evaluated the impact of IS in PFS and ORR.

Methods: This study prospectively evaluated patients with HR+/HER2- aBC treated in the first-line setting with CDK4/6i + ET from February 2015 to January 2022 across 5 hospitals in Spain. Tumor biopsies had been performed within 90 days prior the patient started the CDK4/6i + ET. RNA from FFPE tumors was analyzed at the nCounter® (Nanostring Technologies) using a 72 custom gene panel including the PAM50 genes. The primary objective is to correlate the baseline PAM50 IS with PFS. The Kaplan-Meier method and multivariable cox model PFS analyses were performed adjusting for previous endocrine sensitivity, visceral disease, and metastatic onset disease. Secondary objectives were to estimate the ORR based on RECIST1.1 and its association with IS and the development of a prognostic algorithm that includes clinical and genomic data.

Results: From May 2020 to May 2022, 113 patients with PAM50 results who met all eligibility criteria, including sample quality, were included. IS distribution was 42.5% Luminal A, 46.9% luminal B, 7.1% HER2-enriched, 0.9% basal-like and 2.6% Normal-like (89.4% luminal vs 10.6% non-luminal). Baseline patient characteristics are shown in table 1. The median follow-up for PFS was 18.5 m (interquartile range 10.0 – 31.7m). Median PFS for Luminal vs no-luminal subtypes was 26.8 m (95% CI: 18.9 - 43.8 m) and 10.0 m (95% CI: 5.8 - 26.0 m) (adjusted hazard ratio [aHR]= 2.44 95% IC: 1.17 - 5.07). Median PFS by all IS was not reached (NR) for Luminal A (95% CI: 23.0 – NR); 19.5 m luminal B (95% CI: 15.7 - 27.3 m, aHR vs Luminal A= 1.98 95% IC: 1.09 - 3.62), 10.0 m HER2-E (95% CI: 4.4 - NR, aHR vs Luminal A= 2.75 95% IC: 1.05 - 7.18), 12.4 m Normal-like (95% CI: 5.8 - NR, aHR vs Luminal A= 19.35 95% IC: 2.32 - 160.89) and not estimable for basal-like (aHR vs Luminal A= 5.44 95% IC: 1.44 - 20.60). ORR was not significantly higher in Luminal B (55.1%) and HER2-E (57.1%) subtype versus luminal A (46.3%) (p=0.677). OS follow-up is still immature.

Conclusions: We confirmed the independent prognostic value of the PAM50 IS in first-line HR+/HER2- breast cancer treated with CDK4/6i+ET. Further gene expression analysis and development of a prognostic composite score is ongoing and will be presented at the conference.

This project has received a research grant from “Instituto de Salud Carlos III (ISCIII), Ministerio de Economía y Competitividad” (Spain) awarded within the National Research Program with reference PI 18/01408, co-funded with European Union ERDF funds.

Baseline patient characteristics

Citation Format: Pablo Tolosa, Tomás Pascual, Cristina Hernando, Sonia Servitja, Adela Fernández, Fara Brasó-Maristany, Javier Benitez, Laura Lema, Yolanda Ruano, Lucia Parrilla, Ana María Roncero, Rodrigo Sánchez-Bayona, Manuel Alva, Guillermo Villacampa, María Rocío Moreno-Villa, Jordi Canes, Fernando Salvador, Aleix Prat, Eva Ciruelos. Efficacy analysis of CDK4/6 inhibitors in combination with endocrine therapy treatment in HR+/HER2- breast cancer according to PAM50 intrinsic subtype: primary results of SOLTI-1801_CDK-PREDICT study [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 P5-02-44.

HOPE (SOLTI-1903) breast cancer study: real-world, patient-centric, clinical practice study to assess the impact of genomic data on next treatment decision-choice in patients with locally advanced or metastatic breast cancer

Background

Metastatic breast cancer (mBC) causes nearly all BC-related deaths. Next-generation sequencing (NGS) technologies allow for the application of personalized medicine using targeted therapies that could improve patients' outcomes. However, NGS is not routinely used in the clinical practice and its cost induces access-inequity among patients. We hypothesized that promoting active patient participation in the management of their disease offering access to NGS testing and to the subsequent medical interpretation and recommendations provided by a multidisciplinary molecular advisory board (MAB) could contribute to progressively overcome this challenge. We designed HOPE (SOLTI-1903) breast cancer trial, a study where patients voluntarily lead their inclusion through a digital tool (DT). The main objectives of HOPE study are to empower mBC patients, gather real-world data on the use of molecular information in the management of mBC and to generate evidence to assess the clinical utility for healthcare systems.

Trial design

After self-registration through the DT, the study team validates eligibility criteria and assists patients with mBC in the subsequent steps. Patients get access to the information sheet and sign the informed consent form through an advanced digital signature. Afterwards, they provide the most recent (preferably) metastatic archival tumor sample for DNA-sequencing and a blood sample obtained at the time of disease progression for ctDNA analysis. Paired results are reviewed by the MAB, considering patient's medical history. The MAB provides a further interpretation of molecular results and potential treatment recommendations, including ongoing clinical trials and further (germline) genetic testing. Participants self-document their treatment and disease evolution for the next 2 years. Patients are encouraged to involve their physicians in the study. HOPE also includes a patient empowerment program with educational workshops and videos about mBC and precision medicine in oncology. The primary endpoint of the study was to describe the feasibility of a patient-centric precision oncology program in mBC patients when a comprehensive genomic profile is available to decide on a subsequent line of treatment.

Clinical trial registration

www.soltihope.com, identifier NCT04497285.

SOLTI-1904 ACROPOLI TRIAL: efficacy of spartalizumab monotherapy across tumor-types expressing high levels of PD1 mRNA

Improved selection of cancer patients who are most likely to respond to immune checkpoint inhibitors remains an unmet clinical need. Recently, a positive correlation between levels of PD1 mRNA and clinical outcome in response to PD1 blockade across diverse tumor histologies has been confirmed in several datasets. ACROPOLI is a parallel cohort, non-randomized, phase II study that aims to evaluate the efficacy of the anti-PD1 immune checkpoint inhibitor spartalizumab as monotherapy in metastatic patients with solid tumors that express high levels of PD1 (cohort 1; n = 111). An additional cohort of 30 patients with tumors expressing low levels of PD1, where PD1/PD-L1 antibodies in monotherapy are standard treatment, will also be included (cohort 2). Primary end point is overall response rate in cohort 1. Trial registration number: NCT04802876 (ClinicalTrials.gov).

Abstract OT2-19-03: Solti-1801. Analysis of the efficacy of CDK4/6 inhibitors in combination with hormonal treatment in luminal breast cancer in relation to the intrinsic subtype and markers of immunity (CDK-predict)

Introduction. The incorporation of cyclin-dependent kinase inhibitors 4 and 6 (CDK4/6 inhibitors) with endocrine therapy in patients with hormone receptor-positive/HER2-negative (HR+/HER2-) advanced breast cancer has demonstrated its efficacy improving progression-free survival (PFS), overall response rate (ORR) and, more recently, overall survival (OS). However, patients eventually progress due to resistance to treatment. To date, no clinical or molecular markers defining the HR+/HER2- patient population that obtains the greatest benefit from these drugs have been found, apart from estrogen receptor positivity. However, data from multiple retrospective analysis suggest that within HR+/HER2- disease, the non-luminal intrinsic subtypes (20-30% of these patients) have a worse prognosis and may not benefit equally from every CDK4/6 inhibitor (Finn SABCS 2017, Prat. JCO 2021). Furthermore, the prognostic impact of tumor infiltrating lymphocytes (TILs) and gene expression related to the immune response in the context of HR+/HER2- advanced breast cancer have not been deeply investigated. Design. CDK-PREDICT is an observational, non-interventional, multicenter study that will include 114 patients with advanced breast cancer treated in first-line with CDK4/6 inhibitors + hormone therapy. The primary objective is to correlate the baseline intrinsic subtypes (defined by PAM50) with the efficacy (measured as PFS) of CDK4/6 inhibitors + hormone therapy. As secondary objectives, the correlation of the intrinsic subtypes with ORR and with the histopathological characteristics of the tumor will be analyzed. In addition, the expression of immune response and cell cycle genes, as well as the presence of TILs, will be correlated with the intrinsic subtypes and with PFS and ORR. Formalin-fixed paraffin-embedded (FFPE) tumor tissue samples will be hematoxylin and eosin (H&E) stained and percentage of TILs will be determined. RNA will be purified and analyzed at the nCounter (Nanostring Technologies) using a panel of 72 genes including the PAM50 genes and immune genes such as PD1, PDL1, CD8 or CD4. Overall, we aim to develop a predictive score combining clinical, genomic, and immune expression data integrating tumor biology and microenvironment. For inclusion in the study, a metastatic sample taken within 100 days prior to CDK4/6 inhibitors treatment is required. Once this sample has been collected, registered, and assessed for quality, patients will be followed up every 6 months until disease progression, death or withdrawal from the study. As of July 2021, 80 patients have been included at 5 sites in Spain. This study is included within the Biomarker program of SOLTI. Recruitment of this study started in June 2020. Acknowledgements.This project has received a research grant from “Instituto de Salud Carlos III (ISCIII), Ministerio de Economía y Competitividad” (Spain) awarded within the National Research Program with reference PI 18/01408, co-funded with European Union ERDF funds (European Regional Development Fund).

Citation Format: Pablo Tolosa, Tomás Pascual, Cristina Hernando, Sonia Servitja, María Fernández Abad, Fara Brasó-Maristany, Javier Benítez, Laura Lema, Mario Martínez, Yolanda Ruano, Lucía Parrilla, Alejandra Bernardini, Ana María Roncero, Laia Paré, Jordi Canes, Patricia Villagrasa, Fernando Salvador, Aleix Prat, Eva Ciruelos. Solti-1801. Analysis of the efficacy of CDK4/6 inhibitors in combination with hormonal treatment in luminal breast cancer in relation to the intrinsic subtype and markers of immunity (CDK-predict) [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 OT2-19-03.

Abstract P1-18-34: Solti-1507 IPATHER - A phase Ib study of ipatasertib (IPAT) and dual anti-HER2 therapy with pertuzumab and trastuzumab (HP) in patients with HER2-positive (HER2+) advanced breast cancer (ABC) and a PIK3CA mutation (mut): Results from the first safety cohort

Background The combination of HP and a taxane increases progression-free survival (PFS) and overall survival (OS) in patients with HER2+ ABC. PIK3CA mut can occur in 30-35% of HER2+ tumors, independently of hormone receptor (HR) status. In an exploratory analysis from CLEOPATRA, patients with a tumor harboring a PIK3CA mut had a shorter PFS. The AKT inhibitor IPAT blocks the PI3K/AKT pathway and has activity in PI3K/AKT-altered tumors. Patients and Methods IPATHER (NCT04253561) is an open-label, single-arm, phase Ib study to evaluate the safety and preliminary efficacy of IPAT plus HP in patients with HER2+ ABC with a PIK3CA-mut (detected in tissue or plasma ctDNA in a Central Laboratory) who are candidates to receive maintenance HP after taxane discontinuation in the first line setting for a reason different to progressive disease. The primary objective is to characterize the safety and tolerability of IPAT in combination with HP, and to identify a maximum tolerated dose (MTD) and/or recommended phase 2 dose (RP2D). The study has two phases: a dose safety phase and a dose expansion phase. MTD is defined as the highest dose level at which ≤1 of 6 subjects experience a dose-limiting toxicity (DLT) during the first 28 days of treatment. DLT during first 28 days of therapy is defined as grade ≥3 diarrhea lasting more than 72 hours, grade ≥2 diarrhea lasting more than 5 days, and other non-hematologic or hematologic toxicities that are ≥ grade 3 and probably or definitely related to study therapy. Given the low risk for overlapping toxicities, the first cohort of the dose safety phase tested IPAT at 400 mg orally once daily D1-21 q28d and standard dose HP. Dose level -1 and -2 of IPAT were 300 mg and 200 mg in case dose de-escalation was needed. Loperamide was given as prophylaxis for diarrhea. In HR-positive tumors, endocrine therapy could be started after the DLT period. Here, we present the results of the dose safety phase of IPATHER. Results A total of 6 female patients with PI3KCA-mut/HER2+ ABC were included in the first dose safety cohort. Median age was 52 (41-78), most patients had ECOG 0 (66.6%), and 50% were postmenopausal. Five out of six patients (83.3%) had HR-negative tumors and visceral metastases. Patients received a median of 6 treatment cycles (range 4-7) with taxane plus HP. At the time of the data cut-off (28/02/2021), all the patients remained on treatment. Median follow up is 4 months (range 2-12). Treatment was well tolerated with no DLTs or grade 3/4 adverse events (AEs) observed during the DLT period or the rest of treatment period (Table 1). The most common treatment-related AEs were diarrhea (N=5, [83.3%]) and nausea (N=2,[33.3%]), mostly grade 1. There was no dose reduction and diarrhea was controlled with prophylactic loperamide. A partial response (PR) was observed in one patient, and 5 had stable disease. Of note, the addition of IPAT to HP in the patient with a PR deepened the response achieved during the induction phase with chemotherapy plus HP.

Conclusion IPAT 400 mg orally once daily D1-21 q28d in combination with HP is well tolerated and has shown preliminary signs of efficacy. Given the favourable safety profile, the dose expansion phase testing IPAT 400 mg in combination with HP has started and will include 19 additional patients.

Table 1.Adverse Events during treatment period related with study treatment (IPAT and/or HP).Adverse EventN AEsN patientsGrade 1Grade 2% (N=6)Diarrhea55 (83%)5083%Nausea32 (33%)2033Vomiting21 (17%)1017Anemia11 (17%)1033Lymphopenia11 (17%)1033Gastroesophageal reflux11 (17%)0117Dyspepsia11 (17%)1017Hyporexia11 (17%)1017

Citation Format: Mafalda Oliveira, Eva Ciruelos, Serafín Morales, Joaquín Gavilá, Vanesa Quiroga, Estela Vega, Javier Salvador Bofill, Alexandra Cortegoso, Fernando Henao, Pablo Tolosa, Jordi Canes, Patricia Villagrasa, Xavier Gonzalez Farré, Tomás Pascual, Cristina Saura. Solti-1507 IPATHER - A phase Ib study of ipatasertib (IPAT) and dual anti-HER2 therapy with pertuzumab and trastuzumab (HP) in patients with HER2-positive (HER2+) advanced breast cancer (ABC) and a PIK3CA mutation (mut): Results from the first safety cohort [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 P1-18-34.

Abstract PD8-03: Palbociclib and trastuzumab for HER2-positive metastatic breast cancer (SOLTI-1303 PATRICIA): Final results from cohort A and B, prospective, open-label, multicenter phase II study

Background: CDK4/6 inhibition combined with anti-HER2 therapy is currently being explored in HER2-positive (HER2+) breast cancer (BC). Here, we report the final efficacy and genomic analysis of cohort A and B of the PATRICIA phase II trial evaluating palbociclib in combination with trastuzumab in advanced HER2+ BC. Methods: PATRICIA is a prospective, open-label, multicenter phase II trial. Patients had received 2-4 prior lines of anti-HER2-based regimens. Treatment consisted of palbociclib 200 mg daily for 2 weeks and 1 week off plus trastuzumab. The study was based on a Simon two-stage design comprising three cohorts: estrogen receptor (ER)-negative (cohort A), ER-positive (cohort B1), and ER-positive with letrozole (cohort B2). Patients with ER-positive tumors were randomized to cohorts B1 or B2. Primary endpoint was progression-free survival (PFS) rate at 6 months (PFS6). Secondary objectives included PFS, overall survival (OS) and the association of the research-based PAM50 intrinsic subtyping with PFS and OS. PAM50 was performed from FFPE samples using the nCounter platform. For each sample we calculated the PAM50 signature scores (Basal-like, HER2-E, Luminal A and B, Normal-like), CES, ROR-Subtype, ROR-proliferation and the proliferation signature score. Multivariable Cox regression analyses evaluating PAM50 subtypes, age, performance status, treatment line, type of biopsy, and ER status. Results: Seventy-one patients were recruited (n = 15 in cohort A and 28 in each cohort B). Median follow-up was 42.3 months (IQR 34.7-54.8). The PFS6 rate in cohorts A, B1, and B2 was 33.3% (5/15), 42.8% (12/28), and 46.4% (13/28), respectively. Median PFS was 4.2 months (95% CI 0.7-6.7) in cohort A, 6.0 months (95% CI 4.0-10.6) in cohort B1 and 5.1 months (95% CI 3.7-9.1) in cohort B2. Regarding PAM50, 59 (83.1%) tumors samples (42.4% metastasis) were profiled. 49.2% of the tumor samples were identified as HER2-E, followed by Luminal B (22.0%), Luminal A (16.9%), normal-like (10.2%), and Basal-like (1.7%). Luminal disease defined by PAM50 was independently associated with longer PFS compared with non-luminal disease (10.6 vs. 4.2 months median PFS; adjusted hazard ratio [HR] = 0.34; P = 0.007). Median OS was 21.8 months (95% CI 13.8-32.2) in cohort A, 28.0 months (95% CI 14.2-48.8) in cohort B1 and 34.3 months (95% CI 20.6-47.6) in cohort B2. Luminal disease defined by PAM50 was not independently associated with OS compared with non-luminal disease (34.3 vs. 26.1 months; adjusted HR = 0.753; P = 0.365). Among the 9 PAM50 signatures, expression of 3 signatures were found significantly associated with OS: CES (HR = 0.50; p=0.021), Luminal A score (HR=0.33; p=0.022) and ROR-S (HR=1.018; p=0.027). Conclusion: Our analysis shows that the promising PFS previously reported in trastuzumab pretreated ER-positive/HER2+ advanced breast cancer with a PAM50 Luminal A or B subtype were maintained after a median of >3 years of follow-up. A longer OS was seen in patients with luminal tumors, but results were not statistically significant and could have been influenced by the low sample size. Cohort C of PATRICIA is currently randomizing patients with HR-positive/HER2+, PAM50 Luminal A or B tumors to palbociclib and endocrine therapy plus trastuzumab or treatment of physician’s choice (NCT02448420). Acknowledgements: This study is sponsored by SOLTI and financially supported by Pfizer

Citation Format: Eva Ciruelos, Tomás Pascual, Mafalda Oliveira, Santiago Escrivá-de-Romaní, Sonia Pernas, Laia Paré, Barbara Adamo, Eduardo Martínez, Javier Cortés, Antonia Perelló, Maria Galan, Mireia Melé, Pablo Tolosa, Blanca González-Farré, Patricia Galván, Jordi Canes, Paolo Nuciforo, Xavier Gonzalez, Patricia Villagrasa, Aleix Prat. Palbociclib and trastuzumab for HER2-positive metastatic breast cancer (SOLTI-1303 PATRICIA): Final results from cohort A and B, prospective, open-label, multicenter phase II 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 PD8-03.

First Nationwide Molecular Screening Program in Spain for Patients With Advanced Breast Cancer: Results From the AGATA SOLTI-1301 Study

Background

The SOLTI-1301 AGATA study aimed to assess the feasibility of a multi-institutional molecular screening program to better characterize the genomic landscape of advanced breast cancer (ABC) and to facilitate patient access to matched-targeted therapies in Spain.

Methods

DNA sequencing of 74 cancer-related genes was performed using FFPE tumor samples in three different laboratories with three different gene panels. A multidisciplinary advisory board prospectively recommended potential targeted treatments. The primary objective was to determine the success of matching somatic DNA alteration to an experimental drug/drug class.

Results

Between September 2014 and July 2017, 305 patients with ABC from 10 institutions were enrolled. Tumor sequencing was successful in 260 (85.3%) patients. Median age was 54 (29-80); most tumors were hormone receptor-positive/HER2-negative (74%), followed by triple-negative (14.5%) and HER2-positive (11.5%). Ninety-seven (37%) tumor samples analyzed proceeded from metastatic sites. Somatic mutations were identified in 163 (62.7%) patients, mostly in PIK3CA (34%), TP53 (22%), AKT1 (5%), ESR1 (3%), and ERBB2 (3%) genes. Significant enrichment of AKT1 mutation was observed in metastatic versus primary samples (9% vs. 2%; p=0.01). Genome-driven cancer therapy was recommended in 45% (n=116) of successfully screened patients, 11% (n=13) of whom finally received it. Among these patients, 46.2% had a PFS of ≥6 months on matched therapy.

Conclusions

AGATA is the first nationwide molecular screening program carried out in Spain and we proved that implementing molecular data in the management of ABC is feasible. Although these results are promising, only 11% of the patients with genome-driven cancer therapy received it.

Abstract OT-26-04: Solti-1801. Analysis of the efficacy of CDK4/6 inhibitors in combination with hormonal treatment in luminal breast cancer in relation to the intrinsic subtype and markers of immunity (CDK-PREDICT)

Introduction. The incorporation of cyclin-dependent kinase inhibitors 4 and 6 (CDK4/6 inhibitors) with endocrine therapy in patients with advanced hormone receptor-positive (HR+) breast cancer and without overexpression of the HER2 (HER2-) oncogene has demonstrated its efficacy improving progression-free survival (PFS), overall response rate (ORR) and, more recently, overall survival (OS). However, patients eventually progress due to resistance to treatment. To date, no clinical or molecular markers defining the HR +/HER2- patient population that obtains the greatest benefit from these drugs have been found, apart from estrogen receptor positivity. However, there are data from multiple retrospective analysis suggesting that within HR+/ HER2- disease, the non-luminal intrinsic subtypes (20-30% of these patients) have a worse prognosis and may not benefit from CDK4/6 inhibitors. Furthermore, the prognostic impact of tumor infiltrating lymphocytes (TILs) and gene expression related to the immune response in the context of HR + / HER2- advanced breast cancer have not been deeply investigated.

Design. CDK-PREDICT is an observational, non-interventional, multicenter study that will include 114 patients with advanced breast cancer who have received, are receiving or are going to receive endocrine therapy plus a CDK4/6 inhibitor for, at least, 8 weeks as first-line treatment. The primary objective is to correlate the intrinsic subtypes (defined by PAM50) with the efficacy (measured as PFS) of CDK4/6 inhibitors + hormone therapy. As secondary objectives, the correlation of the intrinsic subtypes with ORR and with the histopathological characteristics of the tumor will be analyzed. In addition, the expression of immune response and cell cycle genes, as well as the presence of TILs, will be correlated with the intrinsic subtypes and with PFS and ORR. Overall, we aim to develop a predictive score combining clinical, genomic and immune expression data integrating tumor biology and microenvironment. For inclusion in the study, a metastatic sample taken within 90 days prior to CDK4/6 inhibitors treatment will be required. Once this sample has been collected, registered and assessed for quality, patients will be followed up every 6 months until disease progression, death or withdrawal from the study.

This project has received a research grant from “Instituto de Salud Carlos III (ISCIII), Ministerio de Economía y Competitividad” (Spain) awarded within the National Research Program with reference PI 18/01408, co-funded with European Union ERDF funds (European Regional Development Fund). This study is included within the Biomarker program of SOLTI. Recruitment of this study started in June 2020.

Citation Format: Pablo Tolosa, Tomás Pascual, Cristina Hernando, Sonia Servitja, María Fernández Abad, Rafael Villanueva, Fernando Henao, Javier Benítez, Laura Lema, Mario Martínez, Yolanda Ruano, Lucía Parrilla, Alejandra Bernardini, Ana María Roncero, Laia Paré, Jordi Canes, Fernando Salvador, Patricia Villagrasa, Aleix Prat, Eva Ciruelos. Solti-1801. Analysis of the efficacy of CDK4/6 inhibitors in combination with hormonal treatment in luminal breast cancer in relation to the intrinsic subtype and markers of immunity (CDK-PREDICT) [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-26-04.

Abstract OT-13-06: Solti-1503 PROMETEO: Talimogene laherparepvec (T-VEC) + atezolizumab combination in early breast cancer

Background Residual disease (RD) after standard neoadjuvant chemotherapy (NAC) is composed of drug resistant cells and associates with increased risk of relapse, especially in triple negative, HER2-positive, and highly proliferative Luminal tumors. Immunotherapy combinations can induce of specific anti-tumor immune responses, such as those mediated by T-cells, and which might represent an additional strategy for the control or elimination of residual tumor cells. Preliminary results in melanoma showed that the combination of T-VEC with an anti PD-L1 or anti CTLA4 has greater efficacy than either therapy alone, without additional safety concerns beyond those expected for each agent. The presence of RD after neoadjuvant chemotherapy (NAC) in early BC patients remains an unmet medical need. We hypothesize that combining T-VEC with Atezolizumab may offer clinical benefit in the preoperative setting for early breast cancer (BC) patients with intermediate to high risk of recurrence who present RD after standard NAC. Methods SOLTI-1503 PROMETEO is an open-label, multicenter trial of T-VEC + Atezolizumab in patients with RD after completing standard NAC. Thirty patients with triple negative BC (TNBC) or Luminal B-like/HER2- will be included. RD must be confirmed by core-biopsy and have a diameter ≥ 15 mm measured by magnetic resonance imaging. Adequate organ function and ECOG PS 0-1 are required. T-VEC is administered intratumorally in week 1 (106 plaque-forming units/mL [pfu/mL]), then in week 4 and every 2 weeks thereafter (108 pfu/mL) for 4 injections. Atezolizumab (840 mg) is administered intravenously every 2 weeks for 4 infusions, beginning in week 4. BC surgery will be carried out 1 to 3 weeks after completion of treatment. A protocol amendment was approved, the steering committee of the study decided to change the primary objective of the trial to a more clinical endpoint that is to evaluate the efficacy by the rate of RCB class 0/1 at surgery. Secondary endpoints include rate of pCR, ORR, safety and the increase of mean expression of a gene signature tracking activated CD8 T-cells. The first safety analysis was performed in October 2019. Independent safety date review board considered the trial safe and supported its continuation. To date, 8 patients have been included at 4 sites in Spain. Second safety and efficacy data analysis is planned after 10 patients have completed treatment. If a rate of PD higher than 50% is observed in the first 10 patients, then the trial will be permanently stopped. We expect to achieve 10 patients in July 2020. We thank AMGEN for their provision of Talimogene Laherparepvec and their financial contribution to this clinical study. We thank ROCHE for their provision of Atezolizumab and their financial contribution to this clinical study. Clinical trial identification: NCT03802604

Citation Format: Tomás Pascual, Juan M Cejalvo, Mafalda Oliveira, Maria Vidal, Estela Vega, Sergi Ganau, Ana Julve, Esther Zamora, Ignacio Miranda, Ana Delgado, Begoña Bermejo, Luis de la Cruz-Merino, Manel Juan, Juan M Ferrero-Cafiero, Jordi Canes, Xavier González-Farré, Patricia Villagrasa, Aleix Prat. Solti-1503 PROMETEO: Talimogene laherparepvec (T-VEC) + atezolizumab combination in 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-13-06.

SOLTI-1503 PROMETEO TRIAL: combination of talimogene laherparepvec with atezolizumab in early breast cancer

New treatment strategies such as immune checkpoint inhibitors and oncolytic viruses are opening new possibilities in cancer therapy. Preliminary results in melanoma and other tumors showed that the combination of talimogene laherparepvec with an anti-PD-1/PD-L1 or anti-CTLA4 has greater efficacy than either therapy alone, without additional safety concerns beyond those expected for each agent. The presence of residual cancer after neoadjuvant chemotherapy in early breast cancer patients is an unmet medical need. SOLTI-1503 PROMETEO is a window of opportunity trial, which evaluates the combination of talimogene laherparepvec in combination with atezolizumab in women with operable HER2-negative breast cancer who present residual disease after neoadjuvant chemotherapy. The primary end point is the rate of residual cancer burden 0/1. Clinical Trial Registration: NCT03802604.

Abstract OT2-02-06: Palbociclib in combination with trastuzumab and endocrine therapy (ET) versus treatment of physician's choice (TPC) in metastatic HER2-positive and hormone receptor-positive (HER2+/HR+) breast cancer with PAM50 luminal intrinsic subtype (SOLTI-1303 PATRICIA II): A multi-center, randomized, open-label, phase II trial

Background: Efficacy Interim results from PATRICIA phase II trial in HER2+/HR+ advanced breast cancer (BC) showed that PAM50 luminal disease was associated with larger and clinically meaningful progression-free survival (PFS) following palbociclib, trastuzumab and endocrine therapy compared to PAM50 non-luminal disease (Ciruelos E. et al, SABCS 2018). Based on these preliminary results, PATRICIA II was designed to select patients based on PAM50 and to include a randomization to a control arm. Trial Design: PATRICIA II is a randomized open-label, adaptive design, phase II study. Eligible patients must have centrally confirmed HR+/HER2+ and PAM50 Luminal A or B intrinsic subtype tumors and have received at least 1 (and no more than 4) prior lines of anti-HER2 regimens for locally advanced or metastatic BC, including a taxane and trastuzumab. Patients are randomized 1:1 to receive trastuzumab in combination with palbociclib at a standard dose of 125 mg/day orally 3 weeks on/1 week off and endocrine therapy (cohort C1) or treatment of physician’s choice (TPC): TDM1 or chemotherapy (gemcitabine, vinorelbine, capecitabine, eribulin, paclitaxel or docetaxel) in combination with trastuzumab (cohort C2). ET options are either an aromatase inhibitor, fulvestrant or tamoxifen. Premenopausal patients (pts) must receive ovarian suppression. Stratification factors include number of previous regimens for advanced BC (1-2 vs 3-4) and the presence of visceral disease (yes vs no). The primary objective is to assess whether the combination of palbociclib, trastuzumab and endocrine therapy is superior to TPC in terms of progression-free survival (PFS) in HER2+, PAM50 Luminal patients. The study has an 80% power with two-sided alpha=0.05 to detect a hazard ratio of 0.62 in favor of the palbociclib arm. An adaptive design will be used to compare both treatment arms. An interim analysis (IA) adjusted for multiplicity from O’Brien-Fleming method and an estimation of the conditional power (CP) will be performed at 70% of the events by an Independent Data Monitoring Committee (IDMC). Key secondary objectives are response rate, overall survival, safety, and Quality of Life. Tumor tissue and blood samples will be collected for biomarker analyses. A total of 516 patients will be screened and 232 patients will be recruited. The trial was activated in June 2019 and the recruitment is ongoing in 20 sites in Spain. The study is sponsored by SOLTI and financially supported by Pfizer.

Citation Format: Eva Ciruelos, Patricia Villagrasa, Mafalda Oliveira, Sonia Pernas, Javier Cortes, Silvia Vazquez, Noelia Martínez, Antonia Perello, Begoña Bermejo, Eduardo Martínez, Isabel Garau, Mireia Melé, Alvaro Montaño, Estela Vega, Blanca Cantos, María Jose Echarri, Tomás Pascual, Jordi Canes, Pamela Céliz, Xavier González, Aleix Prat. Palbociclib in combination with trastuzumab and endocrine therapy (ET) versus treatment of physician's choice (TPC) in metastatic HER2-positive and hormone receptor-positive (HER2+/HR+) breast cancer with PAM50 luminal intrinsic subtype (SOLTI-1303 PATRICIA II): A multi-center, randomized, open-label, phase II 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 OT2-02-06.

Abstract OT1-01-01: SOLTI-1503 PROMETEO: Combination of talimogene laherparepvec (T-VEC) with atezolizumab in patients with residual breast cancer after standard neoadjuvant multi-agent chemotherapy

Background: New strategies as immune blockade inhibitors and oncolytic viruses are opening new possibilities in cancer therapy. Preliminary results in melanoma showed that the combination of Talimogene Laherparevec (T-VEC) with an anti PD-L1 or anti CTLA4 has greater efficacy than either therapy alone, without additional safety concerns beyond those expected for each individual agent. The presence of residual cancer after neoadjuvant chemotherapy (NAC) in early breast cancer (BC) patients is an unmet medical need. We hypothesize that combining T-VEC with Atezolizumab may offer clinical benefit in the preoperative setting for early BC patients with intermediate to high risk of recurrence who present residual disease (RD) after standard NAC.

Methods: PROMETEO is an open-label, multicenter trial of T-VEC in combination with Atezolizumab in patients with residual disease after completing standard NAC. 30 patients with triple negative breast cancer (TNBC) or Luminal B-like/Her2- (ER/PR>10% and Ki-67 ≥30% or ER/PR 1-10% and Ki-67 ≥20%) will be included. RD must be confirmed by core-biopsy and have a diameter ≥ 15mm measured by magnetic resonance imaging. Adequate organ function and ECOG PS 0-1 are required. T-VEC is administered intratumorally in week 1 (106 plaque-forming units/mL [pfu/mL]), then in week 4 and every 2 weeks thereafter (108 pfu/mL) for four injections. Atezolizumab (840 mg) is administered intravenously every 2 weeks for four infusions, beginning in week 4. BC surgery will be carried out 1 to 3 weeks after completion of study treatment. Primary objective is to evaluate the effect of T-VEC + Atezolizumab by comparing the expression of a gene signature tracking activated CD8 T-cells between RD at surgery and RD after NAC. We expect a relative increase of ≥20% in the expression of this CD8 T-cell gene signature in 20% of patients or more, defined as the mean expression of PRF1, CD8A, GZMM, CD8B and FLT3LG, between post and pre-treatment samples. Secondary endpoints include pathologic complete response rate and residual cancer burden, objective response rate, and safety. Two safety data reviews - after 4 and 10 patients complete treatment - are planned. A total of 4 sites in Spain are participating in the trial. To date, 4 patients have been included and it is expected to complete the first safety data review in September 2019. The study recruitment is planned to be completed by October 2020.

Clinical trial identification: NCT03802604

Citation Format: Tomás Pascual, Patricia Villagrasa, María J Vidal, Sergi Ganau, Begoña Bermejo, Ana Julve, Esther Zamora, Ignacio Miranda, Estela Vega, Cristina Marquez, Mafalda Oliveira, Juan Miguel Cejalvo, Luis de la Cruz, Manel Juan, Jordi Canes, Xavier Gonzalez, Aleix Prat. SOLTI-1503 PROMETEO: Combination of talimogene laherparepvec (T-VEC) with atezolizumab in patients with residual breast cancer after standard neoadjuvant multi-agent chemotherapy [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 OT1-01-01.

Oral metronomic vinorelbine combined with endocrine therapy in hormone receptor-positive HER2-negative breast cancer: SOLTI-1501 VENTANA window of opportunity trial

Background

The biological effect of oral metronomic vinorelbine (mVNB) alone or in combination with endocrine therapy in patients with hormone receptor-positive (HR+)/HER2-negative breast cancer has been scarcely addressed.

Methods

Postmenopausal women with untreated stage I–III HR+/HER2-negative breast cancer were randomized (1:1:1) to receive 3 weeks of letrozole (LTZ) 2.5 mg/day, oral mVNB 50 mg 3 days/week, or the combination. The primary objective was to evaluate, within PAM50 Luminal A/B disease, if the anti-proliferative effect of LTZ+mVNB was superior to monotherapy. An anti-proliferative effect was defined as the mean relative decrease of the PAM50 11-gene proliferation score in combination arm vs. both monotherapy arms. Secondary objectives included the evaluation of a comprehensive panel of breast cancer-related genes and safety. An unplanned analysis of stromal tumor-infiltrating lymphocytes (sTILs) was also performed. PAM50 analyses were performed using the nCounter®-based Breast Cancer 360™ gene panel, which includes 752 genes and 32 signatures.

Results

Sixty-one patients were randomized, and 54 paired samples (89%) were analyzed. The main patient characteristics were mean age of 67, mean tumor size of 1.7 cm, mean Ki67 of 14.3%, stage I (55.7%), and grades 1–2 (90%). Most baseline samples were PAM50 Luminal A (74.1%) or B (22.2%). The anti-proliferative effect of 3 weeks of LTZ+mVNB (− 73.2%) was superior to both monotherapy arms combined (− 49.9%; p = 0.001) and mVNB (− 19.1%; p < 0.001). The anti-proliferative effect of LTZ+mVNB (− 73.2%) was numerically higher compared to LTZ (− 65.7%) but did not reach statistical significance (p = 0.328). LTZ+mVNB induced high expression of immune-related genes and gene signatures, including CD8 T cell signature and PDL1 gene and low expression of ER-regulated genes (e.g., progesterone receptor) and cell cycle-related and DNA repair genes. In tumors with ≤ 10% sTILs at baseline, a statistically significant increase in sTILs was observed following LTZ (paired analysis p = 0.049) and LTZ+mVNB (p = 0.012). Grade 3 adverse events occurred in 3.4% of the cases.

Conclusions

Short-term mVNB is well-tolerated and presents anti-proliferative activity alone and in combination with LTZ. The high expression of immune-related biological processes and sTILs observed with the combination opens the possibility of studying this combination with immunotherapy. Further investigation comparing these biological results with other metronomic schedules or drug combinations is warranted.

Trial registration

NCT02802748, registered 16 June 2016.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s13058-019-1195-z.

Abstract P6-18-02: Primary and secondary results of the first nationwide molecular screening program in Spain for patients with advanced breast cancer (AGATA SOLTI-1301 study)

Background: Metastatic breast cancer is the second leading cause of death among women globally. A better understanding of tumor biology, and the availability of high-throughput technologies, have enabled the emergence of precision medicine bringing new expectations and giving rise to molecular screening programs (MSP). SOLTI, as a collaborative Spanish network, designed AGATA, the first multi-institutional MSP ever implemented in this country. Here, we report both the primary and some of the secondary results of the pilot study.

Methods: A total of 10 sites within SOLTI network in Spain participated. DNA-sequencing of 56 cancer related genes was performed using FFPE tumor samples (primary or metastatic). Each clinical case was reviewed by a multidisciplinary advisory board (MAB), which recommended, in a prospective manner, potential experimental treatments, mainly in the context of clinical trials. The primary objective was to determine the success rate of matching a DNA alteration to an experimental drug or drug class. Secondary objectives included a comprehensive molecular characterization of tumor samples by PAM50 subtyping and quantification of protein expression levels by MASS-SPEC (70 proteins panel).

Results: 305 patients (pts) were screened from September 2014 to July 2017 and 260 (85.3%) were finally evaluated by the MAB. Pts characteristics were: mean age 54 years (29-80), ER+/HER2- (n=192; 74%), HER2+ (n=30; 11.5%) and TNBC (n=38; 14.5%). 163 primary tumors and 97 metastatic samples were profiled. Regarding the primary objective, 116 pts (45%) presented at least one mutation (range 1-6) that could be matched to a drug or drug class. Of these, 13 pts (11.2%) received therapy matched to their molecular profile according to the MAB recommendation and their follow-up is still on-going. No mutation was detected in 97 (37%) pts (WT), and 47 patients (18.1%) presented a mutation but no match was possible. The most common mutations were PIK3CA (34%), TP53 (22%), AKT1 (5%), ESR1 (3%) and ERBB2 (3%). Intrinsic subtype distribution in 177 samples was as follows: 34% Luminal A (n=60); 21% Luminal B (n=36); 13% HER2E (n=22); 19% Basal-like (n=34) and 13% Normal-like (n=23). Compared to primary tumors (n=110), the proportion of HER2-enriched disease in metastatic tumors (n=63) was significantly higher (6% vs 20%; p=0.005). Protein expression analysis was performed in 146 samples (94 primary and 57 metastasis). In 19 cases (13%), the outlier expression of some targetable proteins (FGFR1 [n=4, 2.7%], IGF1R [n=4, 2.7%], EGFR [n=1, 0.7%], CEACAM5 [n=6, 4.1%], IDO1 [n=2, 1.37%], TROP2 [n=2, 1.37%]) were identified. Of note, HER2 overexpression (&gt;740 amol/μg) was observed in 4 HER2- cases. Finally, among WT tumors, 21% presented a potential drug-matched protein target.

Conclusions: Nationwide molecular screening in Spain is feasible. Nearly half of patients had tumors with mutation(s), mostly PIK3CA, that could be matched to a potential drug or drug class. PAM50 profile might be helpful to navigate towards a therapeutic decision making, although the MAB could not make any targeted-driven recommendation yet with this data. More clinical evidence is needed to use MASS-SPEC as a diagnostic tool.

Citation Format: Pernas S, Villagrasa P, Nuciforo PG, Vivancos A, Scaltriti M, Rodón J, Burgués O, Canes J, Dueñas M, Cecchi F, Vidal M, Lluch A, Perelló A, Llombart A, Dorca J, Montaño A, Oliveira M, Ribas G, Rapado I, Paré L, Prat A, Ciruelos E. Primary and secondary results of the first nationwide molecular screening program in Spain for patients with advanced breast cancer (AGATA SOLTI-1301 study) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-02.

Abstract P5-11-04: Anti-proliferative effect of oral metronomic vinorelbine (mVNB) in PAM50 Luminal/HER2-negative early breast cancer (SOLTI-1501 VENTANA): A randomized, three-arm, window-of-opportunity study

BACKGROUND: The anti-proliferative effect of mVNB alone or in combination with endocrine therapy in patients with hormone receptor-positive/HER2- breast cancer (BC) has been scarcely addressed.

METHODS: Postmenopausal women with untreated stage I-III BC were randomized (1:1:1) to receive 3 weeks of letrozole (LTZ) 2.5mg/day, oral mVNB 50mg 3 days/week or the combination. The 1ary objective was to evaluate, within PAM50 Luminal A/B disease, if the anti-proliferative effect of mVNB+LTZ was superior to monotherapy. An anti-proliferative effect was defined as the mean relative decrease of the PAM50 11-gene Proliferation Score in each arm. 2ary objectives included safety and the comparison of the anti-proliferative effect between arms. An unplanned analysis of stromal tumor infiltrating lymphocytes (sTILs) was performed. PAM50 analyses were performed using the nCounter®-based Breast Cancer 360TM panel. Changes in the expression of 790 genes/signatures tracking multiple biological processes from tumor cells and the microenvironment were evaluated within each arm using paired (surgery vs. baseline) univariate analyses. P-values were corrected for multiple comparisons using false discovery rate (FDR).

RESULTS: A total of 61 patients were randomized and 54 paired samples (89%) were analyzed. Main patient characteristics were mean age 67, mean tumor size 1.7 cm, stage I (55.7%) and grade 1-2 (90%). Grade 3 toxicities occurred in 3.3% of cases. Baseline samples were Luminal A (72.3%) or B (27.7%). The anti-proliferative effect of mVNB+LTZ (-73.2%) was superior to both monotherapy arms combined (-49.9%; p=0.001) and mVNB (-19.1%; p&lt;0.001). The anti-proliferative effect of mVNB+LTZ (-73.2%) was higher compared to LTZ (-65.7%) but did not reach statistical significance (p=0.328). Across the mVNB+LTZ, LTZ and VNB arms, 413 (52.3%), 403 (51.0%) and 21 (2.6%) genes/signatures were found differentially expressed (FDR&lt;5%) between baseline and surgery samples. Compared to mVNB+LTZ baseline samples, surgical samples showed higher expression of AP-1 transcription factor subunits FOS and JUN, inflammatory chemokines (e.g. CCL4 and IL6), stromal-related genes (e.g. CAV1 and stroma signature) and immune infiltration (e.g. CD8 T-cell signature) and lower expression of proliferation-related genes (e.g. MKI67 and UBE2C), estrogen receptor-signaling and Risk of Recurrence. Of the 413 genes found differentially expressed in surgical samples compared to baseline samples in the mVNB+LTZ arm, 108 (26.2%) were not found in the LTZ arm. Among them, high expression of LAG3, CD24, CD84 and CCR5. Under the microscope, sTILs (≥10% at week 3) were observed in 6.6% (mVNB), 15% (LTZ) and 26% (mVNB+LTZ) of the cases. In tumors with ≤10% TILs at baseline, an increase in TILs was observed following LTZ (p=0.049) and mVNB+LTZ (p=0.012).

CONCLUSIONS: mVNB is well-tolerated and presents antiproliferative activity alone and in combination with LTZ. The increase of activated CD8 T-cells or TILs observed with LTZ+mVNB opens the possibility of studying combinations with immunotherapy. Further investigation comparing these biological results with other metronomic schedules or combinations is warranted.

Citation Format: Prat A, Adamo B, Pascual T, Perez Fidalgo JA, Blanch S, Martínez N, Gomez Pardo P, Lopez Gonzalez A, Murillo Jaso L, Amillano K, Vidal M, Paré L, Canes J, Galvan P, Gonzalez Farre B, Ortega Cebrián V, Gonzalez X, Bellet Ezquerra M, Villagrasa P, Ciruelos E. Anti-proliferative effect of oral metronomic vinorelbine (mVNB) in PAM50 Luminal/HER2-negative early breast cancer (SOLTI-1501 VENTANA): A randomized, three-arm, window-of-opportunity study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-11-04.

Dynamics and dispensability of variant-specific histone H1 Lys-26/Ser-27 and Thr-165 post-translational modifications

In mammals, the linker histone H1, involved in DNA packaging into chromatin, is represented by a family of variants. H1 tails undergo post-translational modifications (PTMs) that can be detected by mass spectrometry. We developed antibodies to analyze several of these as yet unexplored PTMs including the combination of H1.4 K26 acetylation or trimethylation and S27 phosphorylation. H1.2-T165 phosphorylation was detected at S and G2/M phases of the cell cycle and was dispensable for chromatin binding and cell proliferation; while the H1.4-K26 residue was essential for proper cell cycle progression. We conclude that histone H1 PTMs are dynamic over the cell cycle and that the recognition of modified lysines may be affected by phosphorylation of adjacent residues.