924P - Claudin-1 (CLDN1) tight junction protein expression delineates distinct immune infiltrates in ascending (A) vs descending (D) subtypes of nasopharyngeal carcinoma: Potential implications for treatment selection

Background

Distinct ascending (A) and descending (D) subtypes of locally advanced (LA-NPC) with divergent prognosis have been recently described. Prior whole transcriptome profiling (RNAseq) of NPC showed that Claudin-1 (CLDN1) overexpression was correlated with restricted immune infiltration. We sought to investigate CLDN1 expression across A and D subtypes of LA-NPC by RNAseq and validate this association on spatial hyperplex immunofluorescence (mIF).

Methods

We performed RNAseq for 68 LA-NPC patients (35A vs 33D), with corresponding mIF analyses on 16 patients (8A vs 8D). Expression analyses of immune genes and deconvolution (CIBERSORT, quanTIseq) to estimate proportions of immune cell (IC) subsets from RNAseq was done. For mIF, sequential stain-image-strip cycles with two antibodies/cycle was done with COMET (Lunaphore Technologies, CH) for 40 markers (including CK, PD-L1, CD3, CD8, CLDN1), with image analysis done using HALO (Indica Labs, US). >50,000 cells/sample were detected, and every cell was scored positive or negative for each marker based on IF intensity.

Results

CLDN1+ was overexpressed in tumor cells in both A+D at both transcriptomic and protein levels with lower immune gene expression and IC fraction in A compared to D. PD-L1 expression by tumor proportion score (TPS) and composite proportion score (CPS) was significantly higher in A compared to D (p<0.001). Within CLDN1 expressing tumor niches, the ratios of CLDN1+ tumor cell to macrophage, CD8, and CD4 T subpopulations were higher in A compared to D subtype (p<0.001) consistent with immune exclusion in the setting of CLDN1 overexpression.

Conclusions

Resolving tumor heterogeneity can improve upon current therapy. The data presented here confirm that A vs D subtypes have distinct IC composition and PD-L1 expression suggesting potential differences in benefit from checkpoint inhibitors. CLDN1 expression presents another layer of heterogeneity that delineates an immune excluded subpopulation within each subtype. CLDN1 antibody-drug conjugates and inhibitors in development may be useful to overcome immune exclusion moving forward for therapy in NPC.

Clinical trial identification

Editorial acknowledgement

Funding

National Medical Research Council Singapore: Clinician Scientist Award (NMRC/CSA-INV/0027/2018, CSAINV20nov-0021), Duke-NUS Medical School: Oncology Academic Program, Goh Foundation Proton Research Program, National Cancer Centre Singapore: NCCS Cancer Fund, Kua Hong Pak Head and Neck Cancer Research Program.

Disclosure

D.W. Lim: Financial Interests, Institutional, Advisory Board: MSD, Roche, Beigene, Daiichi-Sankyo, Janssen; Financial Interests, Institutional, Trial Chair, Grant funding for investigator-sponsored study: Bristol Myers Squibb, Taiho Pharmaceuticals. M.L.K. Chua: Financial Interests, Personal, Invited Speaker: Varian, AstraZeneca, Janssen, BeiGene, MSD, Bayer; Financial Interests, Personal, Member of Board of Directors: Digital Life Line; Financial Interests, Personal, Stocks/Shares: Digital Life Line; Financial Interests, Institutional, Advisory Board: Digital Life Line; Financial Interests, Institutional, Other, Research agreement: Decipher Biosciences; Financial Interests, Institutional, Research Grant, Grant for an IIT: BeiGene; Non-Financial Interests, Leadership Role: Head and Neck Cancer International Group; Non-Financial Interests, Principal Investigator, PI of an IIT partly sponsored by BeiGene: BeiGene; Non-Financial Interests, Member of Board of Directors, Board of Trustees and Chair of Scientific Committee: Alice's Arc; Non-Financial Interests, Leadership Role, Chair of ASCO Asia Pacific Regional Council: ASCO; Non-Financial Interests, Leadership Role, Chair of the ASCO Breakthrough Meeting 2024: ASCO. All other authors have declared no conflicts of interest.