Updated project metadata. Treatment of glioblastoma with anti-CSF-1R immunotherapy, radiotherapy, or surgical tumor resection were found to all induce a fibrotic response to treatment, which was highly associated with tumor recurrence. To investigate the drivers of fibrotic treatment response we performed multi-omic analysis of the glioblastoma microenvironment following treatment with anti-CSF-1R immunotherapy. Studies consisted of mass spectrometry proteomic analysis, single cell transcriptomics, and high-dimensional spatial analysis. These data identified a protective spatial niche that supported tumor cell survival following treatment, ultimately leading to tumor recurrence. Therapeutic inhibition of fibrotic treatment response blocked the formation of this niche, and significantly improved survival in anti-CSF-1R preclinical trials