1944P - MAGE-A4 and NY-ESO-1 expression analysed in a synovial sarcoma tissue micro-array

Background

T-cell based therapies are currently explored in clinical trials (NCT04044768, NCT01343043) in patients with synovial sarcoma (SySa). These therapies are targeting cancer testis antigens like Melanoma-Associated Antigen 4 (MAGE-A4) or New York Esophageal Squamous Cell Carcinoma-1 (NY-ESO-1). We explored the molecular epidemiology of these targets using a tissue micro-array (TMA) from clinical SySa samples.

Methods

We created a TMA consisting of 323 cores from 108 clinical samples (≥2 cores/sample) from archival, paraffin-embedded material originating from 91 individual donors. A sarcoma reference pathologist verified the diagnosis of SySa in the donor sample. Most samples (62%) were collected from the primary tumour, 22% and 16% originated from a metastasis or local recurrence. Slides were stained with MAGE-A4 antibody (#82491, dilution 1:100, Cell Signaling) and NY-ESO-1 antibody (clone E978, dilution 1:200, Sigma), during an overnight incubation. Normal human testis tissue was used as a positive control. Expression of each core was scored as an H-score, defined as: (% stained cells at 0 intensity) × 0 + (% stained cells at 1+ intensity) × 1 + (% stained cells at 2+ intensity) × 2 + (% stained cells at 3+ intensity) × 3. The average of the H-scores from the cores corresponding to the same tumour sample was used for subsequent analyses. Expression of the target was defined as an average H-score ≥ 1 and high expression was defined as an average H-score > 100. Kruskal-Wallis test was used for the statistical analyses.

Results

Expression of NY-ESO-1 and MAGE-A4 was found in 50.9% (55/108) and 68.5% (74/108) of TMA samples. High expression was noticed in 20/108 samples (18.5%) for NY-ESO-1 and in 25/108 samples (23.1%) for MAGE-A4. In 77.8% of the samples there is at least one of these cancer testis antigens expressed. There was no correlation between the expression level and disease status at the sampling moment, nor with clinical outcome of the patient. Additionally, there was no correlation between the expression level and the size of the original tumour.

Conclusions

MAGE-A4 and NY-ESO-1 are expressed in a clinically relevant proportion of SySa cases represented in our TMA, this supports the utility of these antigens as targets for novel cell-based therapies in this disease.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.