Tumors were minced with micro-dissecting scissors at 4°C in DMEM containing collagenase (1mg/mL, Sigma-Aldrich) and DNase (150 U/mL, Sigma) and incubated at 37°C for 45 minutes with intermittent agitation. Tissues were filtered through a 70-um nylon strainer (Corning). Cells were then incubated in ACK lysing buffer (Life Technologies) for 5 minutes, washed with DMEM and filtered through a 40-um strainer and dead cells were removed by magnetic bead sorting per the manufacturer's protocol (Miltenyi). Next-generation sequencing libraries were prepared using the 10x Genomics Chromium Single Cell 3' Reagent kit v3.1 per manufacturer's instructions. Libraries were uniquely indexed using the Chromium dual Index Kit, pooled, and sequenced on an Illumina NovaSeq 6000 sequencer in a paired-end, dual indexing run.