ERBB3 and neoplasm: ERBB3 alterations were associated with high microsatellite instability (MSI-H: 10.6% vs. 4.5%, P < 0.001), along with elevated tumor mutational burden [TMB; median 4.4 vs. 3.5 mutations per Mb (Mut/Mb), P < 0.001] and TMB-H (≥10 Mut/Mb: 25.1% vs. 11.3%; ≥20 Mut/Mb: 15.9% vs. 5.2%, P < 0.001 for both comparisons).