%0 Journal Article %A Carlos Gomez-Roca %A Philippe Cassier %A Dmitriy Zamarin %A Jean-Pascal Machiels %A Jose Luis Perez Gracia %A F Stephen Hodi %A Alvaro Taus %A Maria Martinez Garcia %A Valentina Boni %A Joseph P Eder %A Navid Hafez %A Ryan Sullivan %A David Mcdermott %A Stephane Champiat %A Sandrine Aspeslagh %A Catherine Terret %A Anna-Maria Jegg %A Wolfgang Jacob %A Michael A Cannarile %A Carola Ries %A Konstanty Korski %A Francesca Michielin %A Randolph Christen %A Galina Babitzki %A Carl Watson %A Georgina Meneses-Lorente %A Martin Weisser %A Dominik Rüttinger %A Jean-Pierre Delord %A Aurelien Marabelle %T Anti-CSF-1R emactuzumab in combination with anti-PD-L1 atezolizumab in advanced solid tumor patients naïve or experienced for immune checkpoint blockade %D 2022 %R 10.1136/jitc-2021-004076 %J Journal for ImmunoTherapy of Cancer %P e004076 %V 10 %N 5 %X Background This phase 1b study (NCT02323191) evaluated the safety, antitumor activity, pharmacokinetics, and pharmacodynamics of colony-stimulating factor-1 receptor-blocking monoclonal antibody (mAb) emactuzumab in combination with the programmed cell death-1 ligand (PD-L1)-blocking mAb atezolizumab in patients with advanced solid tumors naïve or experienced for immune checkpoint blockers (ICBs).Methods Emactuzumab (500–1350 mg flat) and atezolizumab (1200 mg flat) were administered intravenously every 3 weeks. Dose escalation of emactuzumab was conducted using the 3+3 design up to the maximum tolerated dose (MTD) or optimal biological dose (OBD). Extension cohorts to evaluate pharmacodynamics and clinical activity were conducted in metastatic ICB-naive urothelial bladder cancer (UBC) and ICB-pretreated melanoma (MEL), non-small cell lung cancer (NSCLC) and UBC patients.Results Overall, 221 patients were treated. No MTD was reached and the OBD was determined at 1000 mg of emactuzumab in combination with 1200 mg of atezolizumab. Grade ≥3 treatment-related adverse events occurred in 25 (11.3%) patients of which fatigue and rash were the most common (14 patients (6.3%) each). The confirmed objective response rate (ORR) was 9.8% for ICB-naïve UBC, 12.5% for ICB-experienced NSCLC, 8.3% for ICB-experienced UBC and 5.6% for ICB-experienced MEL patients, respectively. Tumor biopsy analyses demonstrated increased activated CD8 +tumor infiltrating T lymphocytes (TILs) associated with clinical benefit in ICB-naïve UBC patients and less tumor-associated macrophage (TAM) reduction in ICB-experienced compared with ICB-naïve patients.Conclusion Emactuzumab in combination with atezolizumab demonstrated a manageable safety profile with increased fatigue and skin rash over usual atezolizumab monotherapy. A considerable ORR was particularly seen in ICB-experienced NSCLC patients. Increase ofCD8 +TILs under therapy appeared to be associated with persistence of a TAM subpopulation.All data relevant to the study are included in the article or uploaded as online supplemental information. %U https://jitc.bmj.com/content/jitc/10/5/e004076.full.pdf