Inducing Fibrosis and Immune Checkpoint Blockade

MMTV-NeuT mice [36 (link)] were obtained from Jackson Labs (FVB-Tg(MMTV-Erbb2)NK1Mul/J) [37 (link)] and FAT-ATTAC mice on a C57BL/6 background were kindly provided by Dr. Philipp Scherer, University of Texas Southwestern [38 (link), 39 (link)]. FAT-ATTAC mice were crossed into the FVB strain and subsequently with MMTV-NeuT mice to produce NeuT/ATTAC mice as previously described [21 (link)]. In brief, NeuT/ATTAC mice at 6 weeks of age were injected i.p. triweekly with 0.4 mg/kg AP20187 throughout tumor development to induce fibrosis [21 (link)]. At 8 weeks of age, mice were injected i.p. twice weekly with 100 μg of the anti-PD-1 monoclonal antibody (mAb) or a matching isotype-specific IgG mAb for four months. This dose achieved a plasma level of 36 ± 3.6 μg/ml (mean ± S.E., N = 21), suggesting even distribution in total blood volume (unpublished results). All treatments and tumor measurements were carried out by Carlos Benitez and Maria Idalia Cruz under the auspices of the Animal Shared Resource.