Dissecting the clinicopathologic, genomic, and immunophenotypic correlates of KRASG12D-mutated non-small-cell lung cancer

Abstract

Background: Allele-specific KRAS inhibitors are an emerging class of cancer therapies. KRAS-mutant (KRAS^MUT) non-small-cell lung cancers (NSCLCs) exhibit heterogeneous outcomes, driven by differences in underlying biology shaped by co-mutations. In contrast to KRAS^G12C NSCLC, KRAS^G12D NSCLC is associated with low/never-smoking status and is largely uncharacterized.

Patients and methods: Clinicopathologic and genomic information were collected from patients with NSCLCs harboring a KRAS mutation at the Dana-Farber Cancer Institute (DFCI), Memorial Sloan Kettering Cancer Center, MD Anderson Cancer Center, and Imperial College of London. Multiplexed immunofluorescence for CK7, programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), Foxp3, and CD8 was carried out on a subset of samples with available tissue at the DFCI. Clinical outcomes to PD-(L)1 inhibition ± chemotherapy were analyzed according to KRAS mutation subtype.

Results: Of 2327 patients with KRAS-mutated (KRAS^MUT) NSCLC, 15% (n = 354) harbored KRAS^G12D. Compared to KRAS^non-G12D NSCLC, KRAS^G12D NSCLC had a lower pack-year (py) smoking history (median 22.5 py versus 30.0 py, P < 0.0001) and was enriched in never smokers (22% versus 5%, P < 0.0001). KRAS^G12D had lower PD-L1 tumor proportion score (TPS) (median 1% versus 5%, P < 0.01) and lower tumor mutation burden (TMB) compared to KRAS^non-G12D (median 8.4 versus 9.9 mt/Mb, P < 0.0001). Of the samples which underwent multiplexed immunofluorescence, KRAS^G12D had lower intratumoral and total CD8⁺PD1⁺ T cells (P < 0.05). Among 850 patients with advanced KRAS^MUT NSCLC who received PD-(L)1-based therapies, KRAS^G12D was associated with a worse objective response rate (ORR) (15.8% versus 28.4%, P = 0.03), progression-free survival (PFS) [hazard ratio (HR) 1.51, 95% confidence interval (CI) 1.45-2.00, P = 0.003], and overall survival (OS; HR 1.45, 1.05-1.99, P = 0.02) to PD-(L)1 inhibition alone but not to chemo-immunotherapy combinations [ORR 30.6% versus 35.7%, P = 0.51; PFS HR 1.28 (95%CI 0.92-1.77), P = 0.13; OS HR 1.36 (95%CI 0.95-1.96), P = 0.09] compared to KRAS^non-G12D.

Conclusions: KRAS^G12D lung cancers harbor distinct clinical, genomic, and immunologic features compared to other KRAS-mutated lung cancers and worse outcomes to PD-(L)1 blockade. Drug development for KRAS^G12D lung cancers will have to take these differences into account.

Keywords: G12D; KRAS; NSCLC; PD-(L)1 blockade.

Figure 1.. Study cohorts and baseline clinicopathologic features of KRAS G12D and KRAS non-G12D NSCLC.

(A) The cohorts of patients included in this study. (B) The distribution of the most common KRAS mutations identified among NSCLCs at the DFCI, MSKCC, MDACC, and Imperial College (n = 2327). (C) Lollipop plot of the most common KRAS mutations identified at participating institutions (n = 2327). (D) The distribution of pack-years across the most common KRAS subtypes. (E) Distribution of metastatic sites in stage IV KRAS^G12D (n = 125) and KRAS^non-G12D (n = 781) NSCLCs in the DFCI cohort. (F) PD-L1 TPS in KRAS^G12D NSCLC and KRAS^non-G12D NSCLC. DFCI, Dana-Farber Cancer Institute; MDACC, MD Anderson Cancer Center; MSKCC, Memorial Sloan Kettering Cancer Center; NSCLC, non-small-cell lung cancer; PD-L1, programmed death-ligand 1; TPS, tumor proportion score.

Figure 2.. Genomic profile of KRAS G12D NSCLC.

(A) Oncoprint of the top 20 genes altered in KRAS^G12D NSCLC. (B) Tumor mutational burden (TMB) in KRAS^G12D and KRAS^non-G12D NSCLC. (C) Volcano plot showing oncogenic gene mutations-enriched KRAS^G12D versus KRAS^non-G12D NSCLC. (D) Prevalence of oncogenic mutations significantly enriched in KRAS^G12D versus KRAS^non-G12D NSCLC. NSCLC, non-small-cell lung cancer.

Figure 3.. Immunophenotypic characteristics of KRAS G12D NSCLC.

(A, B) Representative multiplex immunofluorescence of a KRAS^G12D and a KRAS^non-G12D (in this case, KRAS^G12C) NSCLC sample. Each image shown represents 925 μm × 693 μm from a single 20× region of interest. See Methods for additional details. (C) CD8⁺ T cells (D) PD-1⁺ cells, and (E) CD8⁺PD-1⁺ T cells in KRAS^G12D NSCLC (N = 24) versus KRAS^non-G12D NSCLC (N = 116). (F) Proportion of PD-L1⁺ tumor, non-tumor, and total cells in NSCLCs with KRAS^G12D versus KRAS^non-G12D mutations. Tumor–stroma interface (TSI) CD8⁺, PD-1⁺, and CD8⁺PD-1⁺ cells were examined in 16 KRAS^G12D and 68 KRAS^non-G12D samples in which TSI was included in the biopsy. NSCLC, non-small-cell lung cancer; PD-1, programmed cell death protein 1; PD-L1, programmed death-ligand 1.

Figure 4.. PD-L1 expression and TMB levels according to smoking status among KRAS G12D NSCLCs.

(A) Proportion of NSCLC samples with a PD-L1 TPS of <1%, 1%–49%, and ≥50%, in KRAS^{G12D,light-sm} (<10 pack-years smoking) and KRAS^{G12D,heavy-sm} (≥30 pack-years smoking) subsets. (B) TMB in KRAS^{G12D,light-sm} and KRAS^{G12D,heavy-sm} NSCLCs. NSCLC, non-small-cell lung cancer; PD-L1, programmed death-ligand 1; TMB, tumor mutational burden; TPS, tumor proportion score.

Figure 5.. Clinical outcomes to PD-(L)1 ± chemotherapy in patients with KRAS G12D versus KRAS non-G12D NSCLC.

(A) Objective response rate, (B) progression-free survival, and (C) overall survival to PD-(L)1 blockade monotherapy in patients with advanced KRAS^G12D NSCLC versus KRAS^non-G12D NSCLC. (D) Objective response rate, (E) progression-free survival, and (F) overall survival to PD-(L)1 blockade therapy in combination with chemotherapy in advanced KRAS^G12D NSCLC versus KRAS^non-G12D NSCLC. HR, hazard ratio; NSCLC, non-small-cell lung cancer; PD-L1, programmed death-ligand 1; PFS, progression-free survival; OS, overall survival.