The ratio of CD8 to Treg tumor-infiltrating lymphocytes is associated with response to cisplatin-based neoadjuvant chemotherapy in patients with muscle invasive urothelial carcinoma of the bladder

Abstract

Introduction: Randomized controlled trials of platinum-based neoadjuvant chemotherapy (NAC) for bladder cancer have shown that patients who achieve a pathologic response to NAC exhibit 5 y survival rates of approximately 80-90% while NAC resistant (NR) cases exhibit 5 y survival rates of approximately 30-40%. These findings highlight the need to predict who will benefit from conventional NAC and the need for plausible alternatives.

Methods: The pre-treatment biopsy tissues from a cohort of 41 patients with muscle invasive bladder who were treated with NAC were incorporated in tissue microarray and immunohistochemistry for PD-L1, CD8, and FOXP3 was performed. Percentage of PD-L1 positive tumor cells was measured. Tumor-infiltrating lymphocytes (TIL) densities, along with CD8 and Treg-specific TILs, were measured.

Results: TIL density was strongly correlated with tumor PD-L1 expression, consistent with the mechanism of adaptive immune resistance in bladder cancer. Tumor cell PD-L1 expression was not a significant predictor of response. Neither was the CD8 nor Treg TIL density associated with response. Intriguingly though, the ratio of CD8 to Treg TIL densities was strongly associated with response (p = 0.0003), supporting the hypothesis that the immune system plays a role in the response of bladder cancer to chemotherapy.

Discussion: To our knowledge, this is the first report in bladder cancer showing that the CD8 to Treg TIL density in the pre-treatment tissues is predictive for conventional NAC response. These findings warrant further investigations to both better characterize this association in larger cohorts and begin to elucidate the underlying mechanism(s) of this phenomenon.

Keywords: Biomarkers; bladder cancer; chemotherapy; immunology; neoadjuvant.

Figures

Figure 1.

Spectrum of tumor-infiltrating lymphocytes characterized by MIBC PD-L1 staining. (A) Normalized histograms are shown with the TIL densities (TIL counts per 100 tumors cells) binned into the designated intervals on the x-axes and the sample proportions shown on the y-axes. In each case (overall, CD8, and FOXP3+ TILs) a significant (*Goodman–Kruskal p < 0.01) increase in the amount of TILs is observed with increased MIBC PD-L1 staining. (B) The percentage of cases with MIBC PD-L1 positivity (defined as > 0%) is shown on the x-axes and the per sample CD8/Treg ratio on the y-axes. No statistically significant (NS) association to MIBC PD-L1 expression status was observed.

Figure 2.

Baseline PD-L1 staining in MIBC for patients treated with platinum-based NAC. Representative images of the spectrum of tumor PD-L1 staining across both cNAC responders and resistant MIBC cases are shown. Included in the top left corner of each image is the total counts and row-wise proportions in the cNAC-treated MIBC cohort. No significant different in baseline tumor PD-L1 staining was observed when comparing cNAC responders and resistant cases (Goodman–Kruskal p > 0.05).

Figure 3.

Spectrum of tumor-infiltrating lymphocytes characterized by cNAC response status. (A) Normalized histograms are shown with the TIL densities (TIL counts per 100 tumors cells) binned into the designated intervals on the x-axes and the sample proportions shown on the y-axes. In each case (overall, CD8, and FOXP3+ TILs) no significant (NS, Goodman–Kruskal p > 0.05) difference in the TIL density was observed when comparing cNAC responders and resistant cases. (B) The percentage of cases responsive to cNAC is shown on the x-axis and the per sample CD8/Treg ratio on the y-axes. A striking association is present (*Goodman–Kruskal p = 0.0003), in which a CD8 < Treg TIL composition is strongly associated with cNAC resistance and a CD8 > Treg is better associated with cNAC response.