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Purpose: We previously detected promising efficacy of neoadjuvant nintedanib (a multityrosine kinase inhibitor, TKI) in early HER2-negative breast cancer. In a preclinical study, we monitored stromal hypoxia with 18F-fluoromisonidazole-positron emission tomography (18F-FMISO-PET); we found that reoxygenation of tumors (or lack of it) during a window-of-opportunity (WoO) treatment with TKIs correlated with the benefit (or lack of it) from TKI-plus-chemotherapy combinations. We studied the predictive role of 18F-FMISO-PET for the TKI nintedanib in the neoadjuvant setting in a phase II WoO randomized trial.Experimental Design: Patients were randomized to a 14-day WoO of nintedanib preceded and followed by an 18F-FMISO-PET, followed by nintedanib plus weekly paclitaxel (Arm A) or an 18F-FMISO-PET followed by weekly paclitaxel (Arm B) before surgery. The endpoint was residual cancer burden (RCB). The objective was to detect the patients with no response (RCB-III) on the basis of the baseline or evolutive 18F-FMISO-PET values/changes.Results: One-hundred and thirty HER2-negative patients were randomized. Seventeen (27.9%), 34 (55.7%), and 8 (13.1%) patients had an RCB of III, II, and I/0, respectively, in Arm A. In this arm, baseline hypoxic tumors had a 4.4-fold higher chance of experiencing RCB = 3 (P = 0.036) compared with baseline normoxic tumors. Nintedanib WoO induced tumor reoxygenation in 24.5% of the patients; those not reoxygenating showed a trend toward higher chance of experiencing RCB-III (6.4-fold; P = 0.09). In Arm B, 18F-FMISO-PET lacked predictive/prognostic value.Conclusions: Baseline hypoxic tumors (measured with 18F-FMISO-PET) do not benefit from neoadjuvant nintedanib. Clin Cancer Res; 23(6); 1432–41. ©2016 AACR.

Supplementary Data from Novel Inhibitors of Fatty Acid Synthase with Anticancer Activity

Figure S1 legend

Hypoxic volumes

Purpose: Fatty acid synthase (FASN) is overexpressed in human breast carcinoma. The natural polyphenol (−)-epigallocatechin-3-gallate blocks in vitro FASN activity and leads to apoptosis in breast cancer cells without any effects on carnitine palmitoyltransferase-1 (CPT-1) activity, and in vivo, does not decrease body weight. We synthesized a panel of new polyphenolic compounds and tested their effects on breast cancer models.Experimental Design: We evaluated the in vitro effects of the compounds on breast cancer cell growth (SK-Br3, MCF-7, and MDA-MB-231), apoptosis [as assessed by cleavage of poly(ADP-ribose) polymerase], cell signaling (HER2, ERK1/2, and AKT), and fatty acid metabolism enzymes (FASN and CPT-1). In vivo, we have evaluated their antitumor activity and their effect on body weight in a mice model of BT474 breast cancer cells.Results: Two compounds potently inhibited FASN activity and showed high cytotoxicity. Moreover, the compounds induced apoptosis and caused a marked decrease in the active forms of HER2, AKT, and ERK1/2 proteins. Interestingly, the compounds did not stimulate CPT-1 activity in vitro. We show evidence that one of the FASN inhibitors blocked the growth of BT474 breast cancer xenografts and did not induce weight loss in vivo.Conclusions: The synthesized polyphenolic compounds represent a novel class of FASN inhibitors, with in vitro and in vivo anticancer activity, that do not exhibit cross-activation of β-oxidation and do not induce weight loss in animals. One of the compounds blocked the growth of breast cancer xenografts. These FASN inhibitors may represent new agents for breast cancer treatment. (Clin Cancer Res 2009;15(24):7608–15)

Background: Novel effective and safe therapies are required for advanced TNBC after progression to standard-of-care first line treatment with anti-PD-1/L1 + chemotherapy. We have found that the most aggressive TNBC variants are driven by a heterogeneous set of genetic aberrations that converge in the increased activity of 6 kinases: KIT, PNKP, PRKCE, P70S6K, ERK and CDK6 (Nat Commun; 9:3501-18). Although the inhibition of each kinase in monotherapy yielded little efficacy in preclinical models, the combinations targeting pairs of the former kinases led to therapeutic synergy in most cases. The combined inhibition of CDK6 and ERK led to 5-fold increase in overall survival in preclinical TNBC models (PDXs and spontaneous murine cancer models). The greatest activity was observed in models with increased activity of either CDK6 or ERK. Thus, we aimed to test the safety and preliminary efficacy of combined ERK and CDK6 inhibition with binimetinib and palbociclib in women with advanced TNBC with hyperactivation of ERK and/or CDK6. The combination has been preliminary tested in lung cancer, where a phase I dose-escalation trial established the RP2D in binimetinib 45 mg/BID plus Palbociclib 125 mg daily 21/7. Trial design: Single-arm, prospective, multicentric, open-label, phase IB/II trial with intra-patient dose-escalation. Patients candidate for pre-screening will have determined the activity of ERK and CDK6 with an in-house developed assay and acquisition algorithm at the central lab. Those testing positive for either marker will undergo full screening. Patients will start treatment with continuous oral binimetinib at 45 mg/BID and palbociclib 100 mg/day from days 1 to 21, in 28-day cycles. Patients experiencing ≤ grade 1 tolerable side effects as the greatest toxicity will be allowed to escalate to palbociclib to 125 in cycle 2. Fresh biopsies will be harvested at baseline and disease progression, in order to establish patient-derived organoids (PDOs) and perform WES. PBMCs will be harvested at baseline, +24 hours, and at the beginning of cycle 2, to study changes in the immunophenotype. RECIST 1.1 and NCI CTC AE V 5.0 criteria will be used for assessing disease control (q8 weeks) and toxicity. Eligibility criteria: Pre-screening: Women >18 year old diagnosed of advanced, non-curable TNBC; 2) who have received a minimum of 1 treatment line including immunotherapy; 3) no more than 2 treatment lines for advanced disease; 4) Adequate organ function and recovery from previous toxicity to < tolerable G2. Full screening: 5) Demonstration of hyper-activation of CDK6 and/or ERK in the tumor sample; 6) PD to the previous treatment regimen within the last 28 days. Specific aims: Primary: 1) To determine the progression-free survival time of the combination of binimetinib and palbociclib in TNBC patients with hyperactivation of ERK and/or CDK6 in second/third line 2) To assess the safety and tolerability of the former combination Secondary: 1) 6-month PFS rate, response rate, and overall survival of the combination 2) To study biomarkers of sensitivity and primary and acquired resistance to the combination taking advantage of PDOs 3) To determine the immunodynamics of the combination. Statistical methods: The null hypothesis is that the median PFS time for second/third line TNBC with best physician’s choice is 1.7 months (NEJM; 384:1529-41, 2021). With alpha and beta errors of 0.05 and 0.2, the minimum number of patients to demonstrate a 30% improvement in PFS to 2.5 months is 25. Preliminary data suggest that approximately 40% of the patients show hyper-activation of CDK6 and/or ERK; thus, and assuming a methodological failure of 10%, the minimum number of patients to screen is 69. Present accrual/target accrual: 27 screened of 69 planed; 11 accrued of 25 planned Citation Format: Luis Manso, Alfonso Cortes, Juan M Cejalvo, Serafin Morales, Jose A García Saenz, Ramon Colomer, Rodrigo Sanchez-Bayona, Jorge Silva, Juan A Guerra, Diego Malon, Silvana Mouron, Eduardo Caleiras, Miguel Quintela-Fandino. Phase IB/II trial of palbociclib and binimetinib in advanced triple-negative breast cancer with hyperactivation of ERK and/or CDK4/6 [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 OT2-19-08.

The recent identification of rearrangements of neurotrophic tyrosine receptor kinase (NTRK) genes and the development of specific fusion protein inhibitors, such as larotrectinib and entrectinib, have revolutionized the diagnostic and clinical management of patients presenting with tumours with these alterations. Tumours that harbour NTRK fusions are found in both adults and children and are either rare tumours with common NTRK fusions that may be diagnostic, or more common tumours with rare NTRK fusions. To assess the currently available evidence, 3key Spanish medical societies (the Spanish Society of Medical Oncology (SEOM), the Spanish Society of Pathology (SEAP) and the Spanish Society of Paediatric Haematology and Oncology (SEHOP) have brought together a group of experts to develop a consensus document that includes guidelines on the diagnostic, clinical and therapeutic aspects of NTRK-fusion tumours. It also discusses the challenges related to the routine detection of these genetic alterations in a mostly public health care system.

Objectives Systemic inflammatory response and survival has not been evaluated as a predictive factor of chemotherapy in metastatic pancreatic cancer. The aim of this study was to evaluate the prognostic and predictive value of a baseline Systemic Inflammation Response Index (SIRI) in metastatic pancreatic cancer. Methods Retrospective study of 164 metastatic pancreatic cancer patients. Associations between overall survival (OS), progression free survival (PFS), chemotherapy and SIRI were analyzed. SIRI is defined by neutrophil x monocyte/lymphocyte 109/L. Results Median age 66 years. 22 (13%) received mFOLFIRINOX, 59 (36%) gemcitabine + nab-paclitaxel, 40 (24%) gemcitabine, 13 (8%) other regimens and 30 (18%) had not received treatment. Patients with SIRI Conclusion An elevated SIRI (≥2.3 × 109/L) was an independent prognostic factor for patients with metastatic pancreatic cancer, warranting prospective evaluation.

Background: Intravenous pertuzumab (P IV) + trastuzumab (H IV) + chemotherapy (CT) improves outcomes in patients (pts) with HER2-positive breast cancer, compared with H + CT.A new subcutaneous (SC) formulation, for the first time combining two monoclonal antibodies, P + H, with recombinant human hyaluronidase in one vial, was developed. This ready-to-use fixed-dose combination (PH FDC) is administered subcutaneously into the thigh over 5-8 minutes. The dose of H SC was confirmed in the phase III HannaH trial (NCT00950300) and the dose of P SC was established in a phase Ib study (NCT02738970). We report the first results from FeDeriCa (NCT03493854), which was designed to assess the pharmacokinetics, efficacy, and safety of this novel SC PH FDC compared with H IV + P IV in pts with HER2-positive early breast cancer in the neoadjuvant-adjuvant setting. Methods: Pts with centrally confirmed HER2-positive invasive breast cancer (tumor >2 cm, or node-positive disease; Stage II-IIIC) were randomized 1:1 to receive 8 cycles of CT in the neoadjuvant setting with H IV (loading dose 8 mg/kg, maintenance 6 mg/kg) + P IV (loading dose 840 mg, maintenance 420 mg) (Arm A) or CT per Arm A + PH FDC (loading dose 1200 mg P SC/600 mg H SC, maintenance 600 mg each; Arm B) administered q3w during cycles 5-8. CT was investigator’s choice of either 4 cycles of dose-dense doxorubicin + cyclophosphamide q2w → 4 cycles of weekly paclitaxel (total: 12 weeks), or 4 cycles of doxorubicin + cyclophosphamide q3w → 4 cycles of docetaxel q3w. Post-surgery, pts continued anti-HER2 treatment per randomization to complete 18 cycles. The primary objective was noninferiority (NI) of the pre-dose cycle 8 P serum trough concentration (Ctrough) within the PH FDC versus P IV (NI margin for the lower bound of the 90% confidence interval [CI] of the geometric mean ratio [GMR]: ≥0.8). Key secondary objectives were NI of pre-dose cycle 8 H Ctrough within the PH FDC versus H IV, total pathologic complete response in the breast and axilla (ypT0/is, ypN0; tpCR), and safety (primary cardiac events were defined as heart failure [New York Heart Association III + IV] with significant left ventricular ejection fraction [LVEF] decline; cardiac death. Secondary cardiac events were defined as LVEF decline ≥10% from baseline to below 50% and confirmed LVEF decline). Results: Five-hundred pts were randomized (252 to Arm A, 248 to Arm B - ITT and safety populations) from 06/14/18-12/24/18 at 122 sites. At clinical cutoff (07/04/19), 242 pts (96.0%) in Arm A and 234 (94.4%) in Arm B completed the neoadjuvant treatment phase. Baseline pt demographics and disease characteristics were well balanced between arms.The study met its primary endpoint: P GMR was 1.22 (90% CI 1.14-1.31) with the lower limit of the 90% CI being above the prespecified NI margin of 0.8. H GMR was 1.33 (90% CI 1.24-1.43), meeting the NI criteria. tpCR rates were comparable between arms (59.5%; 95% CI 53.2-65.6 in Arm A and 59.7%; 95% CI 53.3-65.8 in Arm B) and were similar to other P + H + CT trials. Overall safety, including cardiac safety, was comparable between arms (Table). Safety was as expected for P + H + CT trials. Conclusions: SC PH FDC demonstrated noninferior pre-dose cycle 8 P + H Ctrough to that of P IV + H IV, with comparable efficacy and safety. PH FDC offers a faster and simpler method of P + H administration for HER2-positive breast cancer. Pts, %Arm A n = 252Arm B n = 248Any AE in >50% of pts99.6100Alopecia70.277.0Nausea60.358.9Diarrhea55.258.5Grade ≥352.848.8Serious17.916.1CardiacPrimary00.8Secondary3.61.6Asymptomatic LVEF decline needing treatment/discontinuation4.02.0Death0.4*0.4** Unrelated to HER2 treatment Citation Format: Antoinette R Tan, Seock-Ah Im, Andre Mattar, Ramon Colomer, Daniil Stroyakovskii, Zbigniew Nowecki, Michelino De Laurentiis, Jean-Yves Pierga, Kyung Hae Jung, Christian Schem, Sarah Heeson, Mahesh Shivhare, Whitney P. Kirschbrown, Eleonora Restuccia, Tanja Badovinac Crnjevic, Christian Jackisch. Subcutaneous administration of the fixed-dose combination of trastuzumab and pertuzumab in combination with chemotherapy in HER2-positive early breast cancer: Primary analysis of the phase III, multicenter, randomized, open-label, two-arm FeDeriCa 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 PD4-07.

BackgroundNeoadjuvant treatment is increasingly one of the preferred therapeutic options for early breast cancer and may have some unique outcomes, such as identifying predictive and prognostic factors of response or increasing the knowledge of individual tumor biology.DesignA panel of experts from different specialties reviewed published clinical studies on the neoadjuvant management of breast cancer. Recommendations were made that emphasized the clinical multidisciplinary management and the investigational leverage in early breast cancer.ResultsNeoadjuvant therapy has equivalent efficacy to adjuvant therapy, and it has some additional benefits that include increasing breast conservation, assessing tumor response, establishing prognosis based on the pathological response, and providing a “second opportunity” for nonresponding patients. Achieving pathological complete remission because of neoadjuvant therapy has been correlated with long-term clinical benefit, particularly in HER2-positive and triple-negative breast cancer. In addition, the neoadjuvant setting is a powerful model for the development of new drugs and the identification of prognostic markers. Finally, neoadjuvant therapy has proven to be cost-effective by reducing nondrug costs, avoiding radical surgery, and reducing hospital stays when compared with other treatment approaches.ConclusionNeoadjuvant therapy has clinical benefits in early breast cancer and provides in vivo information of individual breast cancer biology while allowing the investigation of new treatment approaches. Access to neoadjuvant therapy should be an option available to all patients with breast cancer through multidisciplinary tumor management.

Background Nivolumab is an anti-cancer monoclonal antibody that inhibits PD1 and modulates T-cell response. It has been shown to significantly improve survival in several types of cancer, but clinical trials have also reported an increased risk of developing immune-related adverse events (IRAEs). Endocrine IRAEs may be particularly relevant. Objective To comprehensively evaluate the clinical presentation of endocrine IRAEs in patients with lung cancer treated with nivolumab. Potential risk factors are analyzed, and strategies for IRAE management are proposed. Methods Forty consecutive patients treated with nivolumab for advanced non-small cell lung cancer (NSCLC) were studied, paying particular attention to development of endocrine IRAEs (thyroid, hypophyseal, adrenal, or pancreatic) and clinical outcome. Results Thyroid function changes were found in 9 patients (22.5%), of which six developed hypothyroidism and three had hyperthyroidism after a median of 3.8 and 2.3 cycles of nivolumab respectively. Only one patient had thyroid-related symptoms. Thyroid autoimmunity was negative in all cases. Hyperthyroid patients showed no uptake in iodine scintigraphy, and their hormone values returned to normal in less than six months. Nivolumab was discontinued for toxicity in one patient. One patient with hyperthyroidism also developed autoimmune diabetes, and one patient with hypothyroidism also had hypogonadism. After a median follow-up of 7.6 months, 25 patients (62.5%) showed response to nivolumab. Univariate and multivariate analyses showed no differences between patients who developed thyroid changes and those who did not. Conclusions Thyroid changes after treatment with nivolumab are common and warrant active laboratory monitoring. The underlying mechanisms and their relevance deserve further research.

Background: The COVID-19 pandemic has emerged as the most important international health problem of the last decades. This study explores the psychopathological implications that Covid-19 has caused on cancer patients during the first wave of the pandemic in Spain. Methods: In this prospective study, we included cancer patients in active treatment from March to June 2020. A 24-question semi-structured questionnaire was designed to measure baseline demographic, clinical and Covid-19 exposure characteristics. Mental health was assessed using the validated Hospital Anxiety and Depression Scale. A descriptive and analytical univariate analysis of the variables studied was performed. Results have been compared with baseline emotional distress rates from historical cohorts in cancer patients. Results: 104 cancer patients were included;a 52.8% of emotional distress, 42.3% of anxiety and 58.6% of depression were detected. 51% of patients expressed higher concern about cancer diagnosis vs COVID-19 infection. Tumor type, stage, type of oncologic treatment or rescheduling of cancer therapy were not related with higher levels of psychological symptomatology. Patients with previous consumption of psychotropic drugs and those who adopted additional infection prevention measures because they considered themselves at risk of having a more aggressive COVID-19 disease had higher levels of emotional distress (p=0.008;p=0.003), anxiety (p=0.026;p=0.004) and depression (p=0.013;p=0.008). Emotional distress was higher in patients whose financial status had worsened (p=0.002). Anxiety rates were higher among patients who often used relaxing therapies (p=0.011) and those who were frequently exposed to media (p=0.05). Depression rates were higher among patients with lower educational level (p=0.032), in those whose economic situation had worsened (p=0.003), and those who relied on Religion or Faith (p=0.029). Conclusions: High rates of emotional distress have been detected during the first wave of the Covid-19 pandemic among cancer patients in active treatment, however, not higher than expected in this population. The cancer disease itself continues to be the main factor of concern for cancer patients, above and beyond the distress generated by Covid-19 pandemic. Legal entity responsible for the study: Hospital Universitario De La Princesa, Medical Oncology Department. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations, Background FGFR1 amplification, but not overexpression, has been related to adverse prognosis in hormone-positive breast cancer (HRPBC). Whether FGFR1 overexpression and amplification are correlated, what is their distribution among luminal A or B HRPBC, and if there is a potential different prognostic role for amplification and overexpression are currently unknown features. The role of FGFR1 inhibitors in HRPBC is also unclear. Methods FGFR1 amplification (FISH) and overexpression (RNAscope) were investigated in a N = 251 HRPBC patients cohort and the METABRIC cohort; effects on survival and FISH-RNAscope concordance were determined. We generated hormonal deprivation resistant (LTED-R) and FGFR1-overexpressing cell line variants of the ER+ MCF7 and T47-D and the ER+, FGFR1-amplified HCC1428 cell lines. The role of ER, CDK4/6, and/or FGFR1 blockade alone or in combinations in Rb phosphorylation, cell cycle, and survival were studied. Results FGFR1 overexpression and amplification was non-concordant in > 20% of the patients, but both were associated to a similar relapse risk (~ 2.5-fold; P, MQF is a recipient of the following grants: AES - PI16/00354 and AES – PI19/00454 funded by the ISCIII (Instituto de Salud Carlos III, Ministry of Science and Innovation, Spain) and co-funded by the European Regional Development Fund (ERDF); 2017/BMD3733 - Call for Coordinated Research Groups from Madrid Region - Madrid Regional Government - ERDF funds. RC and MJB are co-recipients of an AES – PI17/01865 grant funded by the ISCIII and co-funded by the European Regional Development Fund (ERDF). RC is a recipient of funding PIE15/00068, PI20/01458, and PT17/0017/0007 by the ISCIII. This study was partially funded by Bayer Inc. CRIS Contra el Cancer Foundation contributed with a generous donation to this study

Fatty-acid(FA)-synthase(FASN) is a druggable lipogenic oncoprotein whose blockade causes metabolic disruption. Whether drug-induced metabolic perturbation is essential for anticancer drug-action, or is just a secondary-maybe even a defence response-is still unclear. To address this, SKOV3 and OVCAR3 ovarian cancer(OC) cell lines with clear cell and serous histology, two main OC subtypes, were exposed to FASN-inhibitor G28UCM. Growth-inhibition was compared with treatment-induced cell-metabolomes, lipidomes, proteomes and kinomes. SKOV3 and OVCAR3 were equally sensitive to low-dose G28UCM, but SKOV3 was more resistant than OVCAR3 to higher concentrations. Metabolite levels generally decreased upon treatment, but individual acylcarnitines, glycerophospholipids, sphingolipids, amino-acids, biogenic amines, and monosaccharides reacted differently. Drug-induced effects on central-carbon-metabolism and oxidative-phosphorylation (OXPHOS) were essentially different in the two cell lines, since drug-naïve SKOV3 are known to prefer glycolysis, while OVCAR3 favour OXPHOS. Moreover, drug-dependent increase of desaturases and polyunsaturated-fatty-acids (PUFAs) were more pronounced in SKOV3 and appear to correlate with G28UCM-tolerance. In contrast, expression and phosphorylation of proteins that control apoptosis, FA synthesis and membrane-related processes (beta-oxidation, membrane-maintenance, transport, translation, signalling and stress-response) were concordantly affected. Overall, membrane-disruption and second-messenger-silencing were crucial for anticancer drug-action, while metabolic-rewiring was only secondary and may support high-dose-FASN-inhibitor-tolerance. These findings may guide future anti-metabolic cancer intervention. The authors would like to thank Kratos/Shimadzu (Manchester, UK) for providing the MALDI-MS instrumentation used in this study and Dr. Steven Pelech (Kinexus Bioinformatics Corp, Vancouver, BC, Canada) for initial instruction in antibody microarray kinomic analysis. This work was financially supported by the Medical Scientific Fund of the Mayor of the City of Vienna, by the ‘Initiative Krebsforschung’ of the Medical University of Vienna, and by the Herzfelder Familienstiftung, Vienna, Austria. Sí

Summary Background A subcutaneous formulation of pertuzumab and trastuzumab with recombinant human hyaluronidase in one ready-to-use, fixed-dose combination vial (pertuzumab, trastuzumab, and hyaluronidase-zzxf) was approved by the US Food and Drug Administration (FDA) on June 29, 2020. We report the primary analysis of the FeDeriCa study, which was designed to assess the pharmacokinetics, efficacy, and safety of the fixed-dose subcutaneous formulation compared to intravenous pertuzumab plus trastuzumab in patients with HER2-positive early breast cancer in the neoadjuvant–adjuvant setting. Methods FeDeriCa, a randomised, open-label, international, multicentre, non-inferiority, phase 3 study, was done across 106 sites in 19 countries. Patients aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0 or 1, HER2-positive, operable, locally advanced, or inflammatory stage II–IIIC breast cancer, and a left ventricular ejection fraction of 55% or more were randomly assigned (1:1), using a voice-based or web-based response system, to receive intravenous pertuzumab (840 mg loading dose, followed by 420 mg maintenance doses) plus intravenous trastuzumab (8 mg/kg loading dose, followed by 6 mg/kg maintenance doses) or the fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection (1200 mg pertuzumab plus 600 mg trastuzumab loading dose in 15 mL, followed by 600 mg pertuzumab plus 600 mg trastuzumab maintenance doses in 10 mL), both administered every 3 weeks with neoadjuvant chemotherapy. Patients were stratified by hormone receptor status, clinical stage, and chemotherapy regimen. The investigator selected one of the two protocol-approved standard chemotherapy regimens before randomisation. Four cycles of HER2-targeted therapy were administered concurrently with the taxane. After surgery, patients continued the HER2-targeted therapy to receive an additional 14 cycles (total of 18). The primary endpoint was non-inferiority of the cycle 7 pertuzumab serum trough concentration (Ctrough; ie, cycle 8 predose pertuzumab concentration) within the fixed-dose combination for subcutaneous injection versus intravenous pertuzumab plus trastuzumab in the per-protocol pharmacokinetic population (all enrolled patients who adhered to prespecified criteria for pharmacokinetic assessment). Non-inferiority was concluded if the lower bound of the 90% CI of the geometric mean ratio was 0·8 or higher. The safety population included all patients who received at least one dose of study medication, including chemotherapy or HER2-targeted therapy. Enrolment, neoadjuvant therapy, and surgery have been completed; adjuvant treatment and follow-up are ongoing. The trial is registered with ClinicalTrials.gov, NCT03493854. Findings Between June 14, 2018, and Dec 24, 2018, 252 patients were randomly assigned to the intravenous infusion group and 248 to the fixed-dose combination group. The geometric mean ratio of pertuzumab serum Ctrough subcutaneous to serum Ctrough intravenous was 1·22 (90% CI 1·14–1·31). The most common grade 3–4 adverse events occurring during neoadjuvant treatment with HER2-targeted therapy plus chemotherapy in 5% or more of patients were neutropenia (34 [13%] of 252 patients in the intravenous infusion group vs 35 [14%] of 248 patients in the fixed-dose combination group), decreased neutrophil count (31 [12%] vs 27 [11%]), febrile neutropenia (14 [6%] vs 16 [6%]), diarrhoea (12 [5%] vs 17 [7%]), and decreased white blood cell count (18 [7%] vs nine [4%]). At least one treatment-related serious adverse event was reported in 25 (10%) patients in the intravenous infusion group and 26 (10%) patients in the fixed-dose combination group. One patient in each treatment group had an adverse event that led to death (urosepsis in the intravenous infusion group and acute myocardial infarction in the fixed-dose combination group); neither death was related to HER2-targeted therapy. Interpretation The study met its primary endpoint: the fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection provides non-inferior cycle 7 pertuzumab serum Ctrough concentrations to intravenous pertuzumab plus trastuzumab in the neoadjuvant setting with comparable total pathological complete response rates, supporting the FDA approval. Safety was similar between treatment groups, and in line with other pertuzumab, trastuzumab, and chemotherapy trials. Follow-up is ongoing for long-term outcomes, including efficacy and long-term safety. Funding F Hoffmann-La Roche and Genentech.

© The Author(s)., [Background]: Preclinical research suggests that the efficacy of immune checkpoint inhibitors in breast cancer can be enhanced by combining them with antiangiogenics, particularly in a sequential fashion. We sought to explore the efficacy and biomarkers of combining the anti-PD-L1 durvalumab plus the antiangiogenic bevacizumab after bevacizumab monotherapy for advanced HER2-negative breast cancer. [Methods]: Patients had advanced HER2-negative disease that progressed while receiving single-agent bevacizumab maintenance as a part of a previous chemotherapy plus bevacizumab regimen. Treatment consisted of bi-weekly durvalumab plus bevacizumab (10 mg/kg each i.v.). Peripheral-blood mononuclear cells (PBMCs) were obtained before the first durvalumab dose and every 4 weeks and immunophenotyped by flow-cytometry. A fresh pre-durvalumab tumor biopsy was obtained; gene-expression studies and immunohistochemical staining to assess vascular normalization and characterize the immune infiltrate were conducted. Patients were classified as “non-progressors” if they had clinical benefit (SD/PR/CR) at 4 months. The co-primary endpoints were the changes in the percentage T cell subpopulations in PBMCs in progressors versus non-progressors, and PFS/OS time. [Results]: Twenty-six patients were accrued. Median PFS and OS were 3.5 and 11 months; a trend for a longer OS was detected for the hormone-positive subset (19.8 versus 7.4 months in triple-negatives; P = 0.11). Clinical benefit rate at 2 and 4 months was 60% and 44%, respectively, without significant differences between hormone-positive and triple-negative (P = 0.73). Non-progressors’ tumors displayed vascular normalization features as a result of previous bevacizumab, compared with generally abnormal patterns observed in progressors. Non-progressors also showed increased T-effector and T-memory signatures and decreased TREG signatures in gene expression studies in baseline—post-bevacizumab—tumors compared with progressors. Notably, analysis of PBMC populations before durvalumab treatment was concordant with the findings in tumor samples and showed a decreased percentage of circulating TREGs in non-progressors. [Conclusions]: This study reporting on sequential bevacizumab+durvalumab in breast cancer showed encouraging activity in a heavily pre-treated cohort. The correlative studies agree with the preclinical rationale supporting an immunopriming effect exerted by antiangiogenic treatment, probably by reducing TREGs cells both systemically and in tumor tissue. The magnitude of this benefit should be addressed in a randomized setting., MQF is a recipient of the following grants: AES - PI16/00354 funded by the ISCIII and co-funded by the European Regional Development Fund (ERDF) and B2017/BMD3733 (Immunothercan-CM) - Call for Coordinated Research Groups from Madrid Region - Madrid Regional Government - ERDF funds. SM is a recipient of the following grants: Spanish Ministerio de Economía y Competitividad (MINECO) (SAF2017-83732-R; AEI/FEDER, EU) and co-funded by Comunidad de Madrid (B2017/BMD3733; Immunothercan-CM). RC is a recipient RC is a recipient of the ISCIII grants PIE15/00068 and PI17/01865.

Immunotherapy is an effective treatment in advanced cancer, although predictors of response are limited. We studied whether excess weight influences the efficacy outcomes of immunotherapy. We have also evaluated the combined prognostic effect of excess weight and immune-related adverse events (irAEs). Efficacy of anti-PD-1 treatment was evaluated with both objective radiological response (ORR) rate and progression-free survival (PFS), and toxicity with irAEs. We studied the association between excess weight and ORR, PFS or irAEs. 132 patients diagnosed with advanced cancer were included. Median body mass index (BMI) was 24.9 kg/m2. 64 patients had normal weight (BMI, This study was funded in part by the project Discovery, Validation and Implementation of Biomarkers for Precision Oncology [PIE15/00068], and the project FIS PI17/01865 from the Instituto de Salud Carlos III, Ministerio de Economia y Competitividad, awarded to RC, and the projects [JR 17/00007 and PI17/008], awarded to NRL.

Upregulation of fatty acid synthase (FASN) is a common event in cancer, although its mechanistic and potential therapeutic roles are not completely understood. In this study, we establish a key role of FASN during transformation. FASN is required for eliciting the anaplerotic shift of the Krebs cycle observed in cancer cells. However, its main role is to consume acetyl-CoA, which unlocks isocitrate dehydrogenase (IDH)-dependent reductive carboxylation, producing the reductive power necessary to quench reactive oxygen species (ROS) originated during the switch from two-dimensional (2D) to three-dimensional (3D) growth (a necessary hallmark of cancer). Upregulation of FASN elicits the 2D-to-3D switch; however, FASN's synthetic product palmitate is dispensable for this process since cells satisfy their fatty acid requirements from the media. In vivo, genetic deletion or pharmacologic inhibition of FASN before oncogenic activation prevents tumor development and invasive growth. These results render FASN as a potential target for cancer prevention studies., M.Q.F. is a recipient of the following grants: FIS PI13/00430 and FIS PI16/00354 funded by the Instituto de Salud Carlos III (ISCIII) and co-funded by the European Regional Development Fund (ERDF) and AECC Scientific Foundation (Beca de Retorno 2010). R.C. is a recipient of the following grants: FIS PI11/00832 and FIS PI14/00726 funded by the Instituto de Salud Carlos III (ISCIII) and co-funded by the European Regional Development Fund (ERDF), II14/00009 and PIE15/00068 from the Ministerio de Sanidad, Spain. N.S.C. is a recipient of an NIH grant (5R35CA197532). O.Y.T. is a recipient of the grants BFU2014-57466 from the Ministerio de Economía y Competitividad (MINECO). J.P.B. is funded by MINECO (SAF2016-78114-R), Instituto de Salud Carlos III (RD12/0043/0021), Junta de Castilla y León (Escalera de Excelencia CLU-2017-03), Ayudas Equipos Investigación Biomedicina 2017 Fundación BBVA, and Fundación Ramón Areces. This study was partially supported by the generous donations from Fundación CRIS Contra el Cáncer and AVON Spain. We thank Drs. Erwin Wagner and Nabil Djouder for their critical review of the paper.

This consensus statement is a joint initiative of the Spanish Society of Pathology (SEAP) and the Spanish Society of Medical Oncology (SEOM). It revises and updates the recommendations for the use of biomarkers in the diagnosis and treatment of breast cancer. The group of experts recommends that, in all cases of breast cancer, the histologic grade and the alpha-estrogen receptor (ER), progesterone receptor, Ki-67 and HER2 status should be determined, in order to assist prognosis and establish therapeutic options, including hormone therapy, chemotherapy and anti-HER2 therapy. One of the four available genetic prognostic platforms (MammaPrint ® , Oncotype DX ® , Prosigna ® or EndoPredict ® ) may be used in node-negative ER-positive patients to establish a prognostic category and decide, together with the patient, whether adjuvant treatment be limited to hormonal therapy. Newer technologies, including next generation sequencing, liquid biopsy, tumour infiltrating lymphocytes or PD-1 determination, are still investigational.

This consensus statement revises and updates the recommendations for biomarkers use in the diagnosis and treatment of breast cancer, and is a joint initiative of the Spanish Society of Medical Oncology and the Spanish Society of Pathology. This expert group recommends determining in all cases of breast cancer the histologic grade and the alpha-estrogen receptor (ER), progesterone receptor, Ki-67 and HER2 status, in order to assist prognosis and establish therapeutic options, including hormone therapy, chemotherapy and anti-HER2 therapy. One of the four available genetic prognostic platforms (MammaPrint®, Oncotype DX®, Prosigna® or EndoPredict®) may be used in node-negative ER-positive patients to establish a prognostic category and decide with the patient whether adjuvant treatment may be limited to hormonal therapy. Newer technologies including next-generation sequencing, liquid biopsy, tumour-infiltrating lymphocytes or PD-1 determination are at this point investigational.

The landscape of HER2+ metastatic breast cancer (mBC) treatment is changing due to the availability of new anti-HER2 drugs. The purpose of this study was to assess the current treatment patterns and sequences used in HER2+ mBC in the real-world setting. Secondary objectives were to describe the factors that influence the decision to prescribe a first and second-line antitumour treatment. Retrospective chart review of 3068 cases in Spain, Italy, the Netherlands and the UK. First and second-line treatments and regimens are consistent with the clinical guidelines, especially for recently initiated treatments. Age and performance status (PS) of patients impact treatment patterns: younger patients received more innovative treatments than elderly patients. In addition, while most patients received a first antitumor treatment, the rate of patients who continue to subsequent lines of therapy is low (55% transitioning from 1st to 2nd line; 58% from 2nd to 3rd line). Age and PS are key factors in the decision to prescribe further antitumor treatment. Fewer HER2+ mBC patients than expected receive a second and third line therapy. Guidelines should make specific recommendations for older patients or those with a poor PS.

Purpose: We previously detected promising efficacy of neoadjuvant nintedanib (a multityrosine kinase inhibitor, TKI) in early HER2-negative breast cancer. In a preclinical study, we monitored stromal hypoxia with 18F-fluoromisonidazole-positron emission tomography (18F-FMISO-PET); we found that reoxygenation of tumors (or lack of it) during a window-of-opportunity (WoO) treatment with TKIs correlated with the benefit (or lack of it) from TKI-plus-chemotherapy combinations. We studied the predictive role of 18F-FMISO-PET for the TKI nintedanib in the neoadjuvant setting in a phase II WoO randomized trial. Experimental Design: Patients were randomized to a 14-day WoO of nintedanib preceded and followed by an 18F-FMISO-PET, followed by nintedanib plus weekly paclitaxel (Arm A) or an 18F-FMISO-PET followed by weekly paclitaxel (Arm B) before surgery. The endpoint was residual cancer burden (RCB). The objective was to detect the patients with no response (RCB-III) on the basis of the baseline or evolutive 18F-FMISO-PET values/changes. Results: One-hundred and thirty HER2-negative patients were randomized. Seventeen (27.9%), 34 (55.7%), and 8 (13.1%) patients had an RCB of III, II, and I/0, respectively, in Arm A. In this arm, baseline hypoxic tumors had a 4.4-fold higher chance of experiencing RCB = 3 (P = 0.036) compared with baseline normoxic tumors. Nintedanib WoO induced tumor reoxygenation in 24.5% of the patients; those not reoxygenating showed a trend toward higher chance of experiencing RCB-III (6.4-fold; P = 0.09). In Arm B, 18F-FMISO-PET lacked predictive/prognostic value. Conclusions: Baseline hypoxic tumors (measured with 18F-FMISO-PET) do not benefit from neoadjuvant nintedanib. Clin Cancer Res; 23(6); 1432–41. ©2016 AACR.

OBJECTIVES: The purpose of this study was to describe the economic impact of recurrences (locoregional or unresectable/metastatic recurrences [MR]) in patients with HER2+ breast cancer (BC) in Spain. METHODS: A Delphi panel of 15 Spanish oncologists was carried out to define the clinical management (patients' flow and healthcare resources use) of locoregional recurrences (LR) and unresectable or MR in patients with HER2+ BC. Healthcare resources included medication, medical visits, lab and imaging tests, hospitalizations, surgery, adverse events management and treatment of specific metastases (e.g. bone metastases). Additionally, loss of productivity was also estimated. Local unit costs where used in combination with healthcare resources and workdays lost to estimate both the direct and indirect costs of LR and MR in HER2+ BC patients. A deterministic sensitivity analysis was performed to explore the robustness and assess the critical variables of the study. RESULTS: The estimated distribution of recurrences in HER2+ BC patients was: 90% of MR, 7% of LR and 3% of LR followed by an MR. With respect to MRs, 31% of cases were estimated to receive up to 5 lines of treatment whilst 5% received no treatment (10%, 20% and 21% would receive 2, 3 and 4 treatment lines, respectively, with a median of 3 lines). Treatment regimens including trastuzumab were the most frequently used (in combination with pertuzumab and taxane in 1L, and with other combinations in 4&5L). In 3L, the most common treatment regimen was lapatinib-capecitabine. Total costs, including medical and indirect costs were €235,138, being the direct costs more than 88.7% (€208,682). Both direct and total costs were higher in patients being treated with a higher number of treatment lines, with figures ranging from €38,511 (1L) to €308,869 (5L) and €50,908 (1L) and €358,000 (5L) respectively. CONCLUSIONS: HER2+ BC patients with a MR were estimated to receive a median of 3 treatment lines and almost one third receives 5 treatment lines. The direct and indirect costs of recurrences are high, with a calculated average total cost of €235,138. Using targeted therapies in earlier stages of HER2+ BC that achieve a reduction of recurrences would achieve significant cost savings in Spain. Citation Format: Colomer R, Ciruelos E, De la Haba J, Martín M, De Salas-Cansado M, Muñoz-Molina B, Albanell J. Estimating costs of relapsing HER2+ breast cancer in Spain [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-12-05.

OBJECTIVES: Given the increase resource constriction of the healthcare systems, efficiency analyses are become more frequent to give additional information to help decision makers in the adoption of new interventions that have already proved clinical value. The use of a neoadjuvant chemotherapy regimen including pertuzumab, trastuzumab and docetaxel (PTD) has demonstrated to improve pathological complete response (pCR) in patients with HER2+ breast cancer (BC). The objective of this study was to estimate the cost-effectiveness of PTD vs. TD in Spain. METHODS: Clinical outcomes from the NeoSphere trial were combined with local data regarding the use of resources associated to patients' follow-up and management of recurrences in a Markov model. Markov models are commonly used to represent the evolution of cancer patients, the effect on clinical outcomes and costs of alternative treatment strategies. In this study, patients with HER2+ BC were modeled through six different health states (event-free, locoregional-relapse, remission, metastatic-relapse [1L], metastatic-relapse [2L], and death) in two cohorts receiving PTD or TD. Long-term effects were estimated by fitting a log-logistic distribution (other techniques were also explored) to event free survival (EFS) data from the NeoSphere study (prevention of 5% relapses at 5 years) combined with utility estimates from the literature. Other transition probabilities as well as unit costs were also obtained from the literature and validated by a 15-oncologists Delphi panel, as well as the estimation of the patients follow-up and recurrences costs. The effectiveness was expressed in terms of quality adjusted life years (QALY) and the analysis was performed from the perspective of the Spanish National Healthcare System (NHS) over a lifetime horizon (a 3% annual discount rate was used for both costs and effects). Deterministic and probabilistic sensitivity analyses (PSA) were performed to assess the robustness of the model results and the influence of different input parameters. RESULTS: PTD was associated to higher effectiveness than PT (14.007 and 13.447 QALY respectively) and lower lifetime costs (€141.070 € and €148.299 € respectively). PTD was also a dominant option over PT when pathological complete response results from the NeoSphere study were combined with EFS data from the CTNeoBC analysis to estimate long-term results. Both the deterministic and probabilistic sensitivity analyses confirmed the robustness of the results, showing that PTD was a dominant option in more than 90% simulations in the PSA. CONCLUSIONS: Beyond the better long-term health outcomes, the combination of PTD would also result in lower lifetime costs for the Spanish NHS, showing that adding pertuzumab is a dominant strategy in HER2+ BC patients receiving neoadjuvant therapy. Citation Format: Abanell J, Ciruelos E, De la Haba J, Martín M, Muñoz-Molina B, De Salas-Cansado M, Colomer R. Cost-effectiveness analysis of adding neoadjuvant chemotherapy with pertuzumab, in patients with HER2+ breast cancer in Spain [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-12-02.

// Renate Wagner 1, 2 , Gerald Stubiger 2, 3, 4 , Daniel Veigel 1, 2 , Michael Wuczkowski 3, 4 , Peter Lanzerstorfer 5 , Julian Weghuber 5 , Emmanouil Karteris 6 , Karin Nowikovsky 1, 2 , Nastasia Wilfinger-Lutz 1, 2 , Christian F. Singer 7 , Ramon Colomer 8 , Bellinda Benhamu 9 , Maria Luz Lopez-Rodriguez 9 , Peter Valent 2, 10, 11 , Thomas W. Grunt 1, 2, 11 1 Division of Oncology, Department of Medicine I, Medical University Vienna, Vienna, Austria 2 Comprehensive Cancer Center, Medical University Vienna, Vienna, Austria 3 Department of Biomedical Imaging and Image-guided Therapy, Medical University Vienna, Vienna, Austria 4 Center for Biomarker Research in Medicine, Graz, Austria 5 University of Applied Sciences Upper Austria, School of Engineering and Environmental Sciences, Wels, Austria 6 Department of Biosciences, School of Health Sciences and Social Care, Brunel University London, Uxbridge, UK 7 Department of Obstetrics/Gynecology, Medical University Vienna, Vienna, Austria 8 Department of Medical Oncology, Hospital Universitario La Princesa and Spanish National Cancer Research Center (CNIO), Clinical Research Program, Madrid, Spain 9 Departamento de Quimica Organica I, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Madrid, Spain 10 Division of Hematology and Hemostaseology, Department of Medicine I, Medical University Vienna, Vienna, Austria 11 Ludwig Boltzmann Cluster Oncology, Medical University Vienna, Vienna, Austria Correspondence to: Thomas W. Grunt, email: thomas.grunt@meduniwien.ac.at Keywords: AMPK, fatty acid synthase (FASN), lipids, mTORC1, REDD1 Received: February 24, 2016 Accepted: December 24, 2016 Published: January 10, 2017 ABSTRACT Receptor-PI3K-mTORC1 signaling and fatty acid synthase (FASN)-regulated lipid biosynthesis harbor numerous drug targets and are molecularly connected. We hypothesize that unraveling the mechanisms of pathway cross-talk will be useful for designing novel co-targeting strategies for ovarian cancer (OC). The impact of receptor-PI3K-mTORC1 onto FASN is already well-characterized. However, reverse actions–from FASN towards receptor-PI3K-mTORC1–are still elusive. We show that FASN-blockade impairs receptor-PI3K-mTORC1 signaling at multiple levels. Thin-layer chromatography and MALDI-MS/MS reveals that FASN-inhibitors (C75, G28UCM) augment polyunsaturated fatty acids and diminish signaling lipids diacylglycerol (DAG) and phosphatidylinositol 3,4,5-trisphosphate (PIP3) in OC cells (SKOV3, OVCAR-3, A2780, HOC-7). Western blotting and micropatterning demonstrate that FASN-blockers impair phosphorylation/expression of EGF-receptor/ERBB/HER and decrease GRB2–EGF-receptor recruitment leading to PI3K-AKT suppression. FASN-inhibitors activate stress response-genes HIF-1α-REDD1 (RTP801/DIG2/DDIT4) and AMPKα causing mTORC1- and S6-repression. We conclude that FASN-inhibitor-mediated blockade of receptor-PI3K-mTORC1 occurs due to a number of distinct but cooperating processes. Moreover, decrease of PI3K-mTORC1 abolishes cross-repression of MEK-ERK causing ERK activation. Consequently, the MEK-inhibitor selumetinib/AZD6244, in contrast to the PI3K/mTOR-inhibitor dactolisib/NVP-BEZ235, increases growth inhibition when given together with a FASN-blocker. We are the first to provide deep insight on how FASN-inhibition blocks ERBB-PI3K-mTORC1 activity at multiple molecular levels. Moreover, our data encourage therapeutic approaches using FASN-antagonists together with MEK-ERK-inhibitors.

One proposed mechanism through which antiangiogenics exert their effect in epithelial malignancies is by improving the status of the aberrant vascular network and secondarily facilitating the delivery of concurrently administrated cytotoxic agents. During this process, known as vascular normalization, the oxygenation of the tumor is usually improved. Many mechanisms of resistance have been proposed to evade the action of this drug class elicited through this mechanism of action. However, a less explored mechanism of action is vascular choking, as increased hypoxia is thought to be associated with the inevitable progression of certain tumor-promotion features. Here we review the available evidence regarding decreased blood flow as a mechanism of action of antiangiogenics at the preclinical and clinical level. Similar to vascular normalization, there are also escape mechanisms against chronic hypoxia generated by treatment with antiangiogenics. Among other compensatory responses, chronic hypoxia is related with the upregulation of lipidic anabolism. Therefore, we focus on how fatty acid synthase, a key player in this response, can be targeted to delay acquired resistance against antiangiogenics, including experimental data from our group. This effect seems to be specific to those cases in which the antiangiogenic treatment induces a hypoxic response, but not in models where the antiangiogenic agent induced normalizing effects. Whether antiangiogenics induce vascular normalization or a hypoxic environment seems to be tractable with a noninvasive PET-tracer: 18F-fluoromisonidazole PET.

The combined use of a FGFR1 blocker and aromatase inhibitors is appealing for treating breast cancer patients with FGFR1 amplification. However, no pharmacodynamic studies have addressed the effects of this combined target modulation. We conducted a phase 0/I clinical trial in an adjuvant setting, with the goal of obtaining pharmacodynamic proof of the effects of combined aromatase and FGFR1 inhibition and to establish the RP2D for nintedanib combined with letrozole. Patients and methods: Women with early-stage luminal breast cancer were eligible for enrollment in the study. Dose level 1 was nintedanib (150 mg/bid) plus letrozole (2.5 mg/day) administered for a single 28-day cycle (DLT assessment period), followed by a classic 3 + 3 schedule. FGF23 and 17-B-estradiol levels were determined on days 0 and 15; pharmacokinetic parameters were assessed on days 1 and 28. Patients were allowed to continue treatment for 6 cycles. The primary study endpoint was a demonstration of FGFR1 modulation (defined as a 25% increase in the plasma FGF23 level). Results: A total of 19 patients were enrolled in the study (10 in the expansion cohort following dose escalation). At the RP2D (nintedanib 200 mg/bid plus letrozole 2.5 mg/day), we observed a 55% mean increase in the plasma FGF23 level, and 81.2% of the patients had no detectable level of 17-B-estradiol in their plasma (87.5% of the patients treated with letrozole alone). Nintedanib and letrozole displayed a pharmacokinetic interaction that led to three- and twofold increases in their respective plasma concentrations. Most G3 toxic events (5 out of 6: 2 diarrhea and 3 hypertransaminasemia) occurred subsequent to the DLT assessment period. Conclusion: Combined treatment with nintedanib (200 mg/bid) plus letrozole (2.5 mg/day) effectively suppressed FGFR1 and aromatase activity, and these respective doses can be used as starting doses in any subsequent trials. However, drug-drug interactions may produce tolerability issues when these drugs are co-administered for an extended time period (e.g., 6 months). Patients enrolled in future trials with these drugs should be carefully monitored for their FGF23 levels and signs of toxicity, and those findings should guide individualized treatment decisions, MQF is a recipient of the following grants: AES - PI16/00354 funded by the ISCIII and co-funded by the European Regional Development Fund (ERDF) and B2017/BMD3733 - Call for Coordinated Research Groups from Madrid Region - Madrid Regional Government - ERDF funds. RC is a recipient of the following grants: AES PI17/01865 and PIE15/00068 by the ISCIII and co-funded by the European Regional Development Fund (ERDF). This study was partially funded by Boehringer-Ingelheim. CRIS Contra el Cancer Foundation contributed with a generous donation to this study