Background: In melanoma (mel) patients (pts) treated with immune checkpoint inhibitors, presence of HLA class I (HLA-1) B44 supertype (B44+) correlated with survival (Chowell, Science). B44 preferentially binds negatively charged (neg) peptides and those with glutamic acid (E) at the anchor position. Positively charged (pos) peptides impede binding. In mel, B44 benefit was driven by glycine (G) > E changes. We evaluated the predictive role of HLA-I supertypes in NSCLC as neoepitopes are likely different as tranversions (Tv) predominate in smokers compared to transitions (Ti) in mel. Methods: 58 advanced NSCLC pts treated with pembrolizumab with 3 years follow up and sufficient PBMCs and/or tumor sample had multiplexed paired-end WES with Illumina HiSeq 2000/3000. HLA typing used BWA-ALN and Athlates software; supertype was determined by 2008 criteria (Sidney, BMC Immunol). Overall survival (OS) and progression-free survival (PFS) were compared by supertype using non-parametric log-rank tests. Tumor variant amino acids (vAA) were identified by GATK best practices, and AA charge was derived from standard charts with stop codons considered uncharged (unc). Ti/Tv and charge change analysis used two-proportion z-tests. Statistical analyses were performed with SPSS V24 (Armonk, NY). Results: Of 9 supertypes evaluated, only absence of B44 supertype (B44-) had longer OS [median OS of 14.9 months (m) vs 9.2 m in B44+ (HR 0.55, 95% CI 0.30-0.99, p = 0.048)], driven by B44- smokers [median OS 21.5 m vs 8.5 m in all other pts (HR 0.50, 95% CI 0.26-0.995, p = 0.048)]. PFS and response rate trends were similar to OS. vAA charge changes from unc/pos to neg in 14/384 (3.6%) Tv and 8/192 (4.2%) Ti (NS) and from unc/neg to pos in 48/384 (12.5%) Tv vs 12/192 (6.3%) Ti (p = 0.019). G > E is not possible from Tv. Among pts with evaluated tumors, Ti/Tv, vAA charge, and G > E were as predicted. Conclusions: Like mel, the B44 supertype associates with OS in NSCLC, however with the opposite effect direction, driven by favorable OS in B44- smokers. A potential mechanism for these histology-specific results is the greater likelihood of Tv in smokers that may lead to neoepitopes with characteristics less favorable for presentation on HLA B44.