Abstract OT-35-01: Solti-1507 A phase ib study of ipatasertib and anti-her2 therapy in her2-positive advanced breast cancer with pik3ca mutation (ipather)

Background The combination of trastuzumab, pertuzumab (HP) and a taxane increases progression-free survival (PFS) and overall survival (OS) in patients with HER2-positive (HER2+) advanced breast cancer (BC). PIK3CA mutations 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 mutation (mut) had a shorter PFS. The AKT inhibitor ipatasertib (IPAT) blocks the PI3K/AKT pathway and has activity in PI3K/AKT-altered tumors. We hypothesize that ipatasertib + HP is safe and can be beneficial in patients with PIK3CAmut HER2+ BC. Trial design This is an open-label, single arm, phase Ib study to evaluate the safety and preliminary efficacy of IPAT plus HP (+/- endocrine therapy [ET]) in patients with PIK3CA mut HER2+ BC. Key inclusion criteria include the presence of locally advanced/unresectable or metastatic HER2+ BC with a PIK3CA mut (detected in tissue or plasma ctDNA); candidates to receive maintenance HP (+/- ET) after taxane discontinuation in first line setting for a reason different to progressive disease; male and female (pre and postmenopausal status); adequate performance status (ECOG 0-1); and adequate bone marrow, cardiac and hepatic function. Key exclusion criteria include: active or progressive brain metastases; diabetes mellitus requiring insulin, and prior exposure to an AKT inhibitor. The primary endpoint is to define the maximum tolerated dose (MTD) and the recommended phase 2 dose of the combination. 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. Grade ≥3 diarrhea for more than 72 hours or Grade ≥2 diarrhea for more than 5 days are considered DLTs amongst others. Secondary endpoints include objective response rate, duration of response, clinical benefit rate and PFS. Exploratory objectives include identification of molecular biomarkers of response to treatment both in ctDNA (Amplicon-seq) and tumor tissue (Breast Cancer 360 panel), as well as to characterize the pharmacokinetics of study drugs. Given the low risk for overlapping toxicities, full doses of IPAT (400mg orally once daily D1-21 q28d) and standard dose HP will be used in the first cohort. Dose reductions of IPAT (300mg and 200mg) are allowed if the full dose exceeds MTD. Loperamide is given as prophylaxis for diarrhea. In HR-positive tumors, ET may be started after the DLT period. Approximately 25 evaluable patients in a given dose level will be required to assess the safety of the combination of IPAT plus HP. Patients are currently being screened for PIK3CA mutations at 7 sites in Spain. The first patient was enrolled in March 2020 and the recruitment is ongoing. This study is sponsored by SOLTI and financially supported by Roche. For further information on this trial, visit ClinicalTrials.gov (NCT04253561)

Citation Format: Mafalda Oliveira, Patricia Villagrasa, Eva Ciruelos, Joaquín Gavilá, Alexandra Cortegoso, Fernando Henao, Estela Vega, Javier S. Bofill, Vanesa Quiroga, Laura García-Estevez, Serafín Morales, Pablo Tolosa, Pamela Céliz, Xavier Gonzalez Farré, Cristina Saura. Solti-1507 A phase ib study of ipatasertib and anti-her2 therapy in her2-positive advanced breast cancer with pik3ca mutation (ipather) [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-35-01.

Phase 2 study of buparlisib (BKM120), a pan-class I PI3K inhibitor, in patients with metastatic triple-negative breast cancer

BACKGROUND

Treatment options for triple-negative breast cancer remain limited. Activation of the PI3K pathway via loss of PTEN and/or INPP4B is common. Buparlisib is an orally bioavailable, pan-class I PI3K inhibitor. We evaluated the safety and efficacy of buparlisib in patients with metastatic triple-negative breast cancer.

METHODS

This was a single-arm phase 2 study enrolling patients with triple-negative metastatic breast cancer. Patients were treated with buparlisib at a starting dose of 100 mg daily. The primary endpoint was clinical benefit, defined as confirmed complete response (CR), partial response (PR), or stable disease (SD) for ≥ 4 months, per RECIST 1.1. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and toxicity. A subset of patients underwent pre- and on-treatment tumor tissue biopsies for correlative studies.

RESULTS

Fifty patients were enrolled. Median number of cycles was 2 (range 1-10). The clinical benefit rate was 12% (6 patients, all SD ≥ 4 months). Median PFS was 1.8 months (95% confidence interval [CI] 1.6-2.3). Median OS was 11.2 months (95% CI 6.2-25). The most frequent adverse events were fatigue (58% all grades, 8% grade 3), nausea (34% all grades, none grade 3), hyperglycemia (34% all grades, 4% grade 3), and anorexia (30% all grades, 2% grade 3). Eighteen percent of patients experienced depression (12% grade 1, 6% grade 2) and anxiety (10% grade 1, 8% grade 2). Alterations in PIK3CA/AKT1/PTEN were present in 6/27 patients with available targeted DNA sequencing (MSK-IMPACT), 3 of whom achieved SD as best overall response though none with clinical benefit ≥ 4 months. Of five patients with paired baseline and on-treatment biopsies, reverse phase protein arrays (RPPA) analysis demonstrated reduction of S6 phosphorylation in 2 of 3 patients who achieved SD, and in none of the patients with progressive disease.

CONCLUSIONS

Buparlisib was associated with prolonged SD in a very small subset of patients with triple-negative breast cancer; however, no confirmed objective responses were observed. Downmodulation of key nodes in the PI3K pathway was observed in patients who achieved SD. PI3K pathway inhibition alone may be insufficient as a therapeutic strategy for triple-negative breast cancer.

TRIAL REGISTRATION

NCT01790932 . Registered on 13 February 2013; NCT01629615 . Registered on 27 June 2012.

Abstract P2-11-01: Immune response following neoadjuvant ribociclib plus letrozole versus chemotherapy in PAM50 Luminal B early breast cancer: A correlative analysis of the SOLTI-1402 CORALLEEN phase 2 randomized trial

Background: CDK4/6 inhibitors increase tumor immunogenicity in preclinical models of breast cancer and several trials combining CDK4/6 inhibitors and anti-PD1/PDL1 therapies are underway. However, immune response data in tumor samples from patients (pts) treated with CDK4/6 inhibitors are scarce. Here, we present exploratory results of the CORALLEEN trial, which evaluated the efficacy of ribociclib and endocrine therapy in patients with high-risk Luminal B disease (Gavilá et al. submitted to SABCS 2019). Methods: CORALLEEN is a randomized exploratory study in postmenopausal women with operable stage I-III breast cancer, hormone receptor positive (HR+)/HER2-negative and Luminal B by Prosigna®. Pts were randomized 1:1 to receive either 6 cycles of ribociclib (600mg; 3-weeks-on/1-week-off) plus daily letrozole (R+L) or chemotherapy (CHT): 4 cycles of AC followed by 12 doses of weekly paclitaxel. The primary endpoint is the rate of PAM50 Risk of Relapse (ROR)-low disease at surgery in each arm. Baseline and surgical specimens were also collected for stromal tumor infiltrating lymphocyte (TIL) determination and gene expression analysis. Expression of 770 genes and 31 biological signatures were determined using the Breast360TM panel (nCounter). In order to identify genes whose expression correlated with TIL, a significance of microarrays (SAM) quantitative analysis was used with a false discovery rate (FDR) <5%. Finally, interaction tests between each variable and tumor ROR response (i.e. relative decrease in ROR score) according to type of therapy were explored in logistic regression models. Results: From July-2017 to Nov-2018, 198 pts were screened and 106 (54%) pts with Luminal B disease were recruited. baseline characteristics were: mean age 64, mean tumor size 3.8 cm, N+ (39%), mean Ki67 33.2%; 86.8% of pts were ROR-high. A total of 95 pts (90%) were included in this analysis (46 pts in the CHT arm and 49 in the R+L arm). At baseline, 21.7% and 32.7% of pts in the CHT and R+L arms had ≥10% of TILs, respectively. Compared to baseline, no significant change patterns in TILs expression were observed. In the CHT arm, 32.6%, 28.3 % and 39.1% of tumors increased, decreased or did not show any change in TILs. In the R+L arm, 30.6%, 44.9% and 24.5% of tumors increased, decreased or did not show any change in TILs. At surgery, 15.2% of pts in the CHT arm and 26.5% of pts in the R+L arm had ≥10% of TILs. Moreover, 5 of the 13 pts (38.5%) with ≥10% of TILs at surgery following R+L had TILs < 10% at baseline. In both arms, high expression of immune-related genes and signatures tracking CD8 T-cells (i.e. CD8A, PD1, LAG3 and CD8T-cell signature) were found associated with high TILs (FDR<5%). when immune response was evaluated based on tumor ROR response (as a continuous variable), high TILs at surgery were associated with better response to CHT but not to R+L (interaction P=0.03). In the CHT arm, mean % of TILs at surgery in low and high ROR responders (defined as <50% or ≥50% relative decrease in ROR score) were 4.2% and 11.2%, respectively. In the R+L arm, mean % of TILs at surgery in low and high ROR responders were 16.2% and 6.1%, respectively. Similar results were found with genes/signatures such as CD8A mRNA (interaction P=0.03), CD8 T-cell signature (interaction P=0.04), Tumor Inflammation Signature (interaction P=0.04) and GZMA mRNA (Granzyme A, interaction P=0.02). Conclusions: An increase in TILs following 24-weeks of R+L occurs in ~30% of pts with high-risk Luminal B tumors, regardless of tumor ROR response. These findings suggest that immune checkpoint blockade might be an interesting strategy to explore in patients with a low ROR response after R+L.

Citation Format: Nuria Chic, Blanca González Farré, Laia Paré, Tomás Pascual, Cristina Saura, Cristina Hernando, Montserrat Muñoz, Pedro Fernandez, Patricia Galván, Xavier González Farré, Mafalda Oliveira, Miguel Gil Gil, Pamela Céliz, Eva Ciruelos, Patricia Villagrasa, Joaquín Gavilá, Aleix Prat. Immune response following neoadjuvant ribociclib plus letrozole versus chemotherapy in PAM50 Luminal B early breast cancer: A correlative analysis of the SOLTI-1402 CORALLEEN phase 2 randomized trial [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-11-01.

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 GS2-06: Primary results of SOLTI-1402/CORALLEEN phase 2 trial of neoadjuvant ribociclib plus letrozole versus chemotherapy in PAM50 Luminal B early breast cancer: An open-label, multicenter, two-arm, randomized study

Background: Different approaches for treatment de-escalation are being investigated; however, the current ongoing phase III adjuvant trials with CDK4/6 inhibitors are not addressing the question if these drugs can replace multi-agent chemotherapy in high-risk early breast cancer. Here, we present the primary results of the CORALLEEN phase 2 trial, which evaluates the efficacy of ribociclib plus endocrine therapy (ET) as neoadjuvant treatment in patients with high-risk Luminal B disease. Methods: CORALLEEN is a parallel, multicenter, two-arm, randomized exploratory study in postmenopausal women with primary operable hormone receptor-positive (HR+)/HER2-negative breast cancer, Luminal B by Prosigna®. Other eligibility criteria include stage I-III operable breast cancer and ECOG 0-1. Patients were randomized 1:1 to receive either six 28-days cycles of ribociclib (600mg; 3-weeks-on/1-week-off) plus daily letrozole (2.5mg) or chemotherapy (CT): 4 cycles of AC (doxorubicin 60 mg/m2 and cyclophosphamide 600 mg/m2 every 21 days) followed by weekly paclitaxel (80 mg/m2) during 12 weeks. Baseline, Day 15 on-treatment, and surgical specimens were collected for molecular characterization and evaluation of response. The primary endpoint is the rate of PAM50 Risk of Relapse (ROR)-low disease at surgery in each arm. PAM50 ROR score integrates gene expression data, tumor size, and nodal status to define a low-risk group in the adjuvant setting (i.e. >90% distant relapse-free survival at 10 years). ROR-low was defined using the standard cutpoints as <40 points if pathologically node-negative (at surgery) and <15 points if 1-3 positive nodes (at surgery). The trial was designed to estimate the rate of ROR-low disease at surgery in each arm without a formal comparison. A total of 47 evaluable patients per arm and an expected ROR-low rate of 25%, would allow a precision of the estimate between 11.5% and 12.4%. Secondary endpoints included safety, intrinsic subtype at surgery, residual cancer burden (RCB), and Preoperative Endocrine Prognostic Index (PEPI). Results: From July 2017 to November 2018, 198 patients were screened with Prosigna® across 21 sites in Spain. From these, 106 (54%) patients with Luminal B disease were recruited, and 96 (90.6%) completed treatment as planned. Main baseline patient characteristics were similar between both treatment arms: mean age 64, mean tumor size 3.8 cm, N+ 39%, mean Ki67 33.2%, and mean ROR score 72.9 (86.8% were ROR-high). A total of 101 (95.3%) surgical samples were analyzed. ROR-low rates at surgery in the ribociclib+ET and CT arms were 48% (95%CI 33.7-62.6) and 47.1% (95%CI 32.9-61.5), respectively. Intrinsic subtype conversion to Luminal A at surgery occurred in 88% of patients in the ribociclib+ET arm and in 84.3% in the CT arm. The rates of RCB0/1 and PEPI 0 in the ribociclib+ET arm were 8% (95%CI 2.2-19.2) and 24% (95%CI 13.1-38.2), respectively. The rates of RCB0/1 and PEPI 0 in the CT arm were 11.8% (95%CI 4.4-23.9) and 17.6% (95%CI 8.4-30.9). Grade 3-4 toxicities were observed in 54.9% of the patients in the ribociclib+ET arm and 69.2% in the CT arm. Additional correlative molecular analyses will be presented. Conclusions: Neoadjuvant ribociclib and letrozole in high-risk Luminal B breast cancer achieves similar rates of ROR-low disease at surgery as multi-agent chemotherapy. Future studies in high-risk early breast cancer evaluating the survival outcomes and quality of life of this combination in the absence of cytotoxic therapy are justified.

Citation Format: Joaquín Gavilá, Cristina Saura, Tomás Pascual, Cristina Hernando, Montserrat Muñoz, Laia Paré, Blanca González Farré, Pedro Fernandez, Patricia Galván, Xavier González Farré, Mafalda Oliveira, Miguel Gil Gil, Miriam Arumi, Neus Ferrer Tur, Alvaro Montaño, Yan Izarzugaza, Antonio Llombart Cussac, Raquel Bratos, Santiago González, Eduardo Martínez, Sergio Hoyos, Beatriz Rojas, Juan Antonio Virizuela, Vanesa Ortega, Rafael López, Pamela Céliz, Eva Ciruelos, Patricia Villagrasa, Aleix Prat. Primary results of SOLTI-1402/CORALLEEN phase 2 trial of neoadjuvant ribociclib plus letrozole versus chemotherapy in PAM50 Luminal B early breast cancer: An open-label, multicenter, two-arm, randomized 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 GS2-06.

Palbociclib and ribociclib in breast cancer: consensus workshop on the management of concomitant medication

Drug–drug interactions are of significant concern in clinical practice in oncology, particularly in patients receiving Cyclin-dependent kinase (CDK) 4/6 inhibitors, which are typically exposed to long-term regimens. This article presents the highlights from the ‘First Workshop on Pharmacology and Management of CDK4/6 Inhibitors: Consensus about Concomitant Medications’. The article is structured into two modules. The educational module includes background information regarding drug metabolism, corrected QT (QTc) interval abnormalities, management of psychotropic drugs and a comprehensive review of selected adverse effects of palbociclib and ribociclib. The collaborative module presents the conclusions of the five working groups, each of which comprised five experts from different fields. From these conclusions positive lists of drugs for treating common comorbid conditions that can be safely administered concomitantly with palbociclib and/or ribociclib were developed.