Poster Presentation 38th Lorne Cancer Conference 2026

B Cells and Tertiary Lymphoid Structures as Predictors of Prostate Cancer Outcomes (#136)

Jessica Da Gama Duarte 1 2 , Luke T Quigley 1 2 , Leire Moya 3 , Louise Jackett 4 , Andrew Weickhardt 5 , Jyotsna Batra 3 , Andreas Behren 5 6
  1. Department of Cancer Medicine, School of Translational Medicine, Monash University, Melbourne, VIC, Australia
  2. Olivia Newton-John Cancer Research Institute, School of Cancer Medicine, La Trobe University, Heidelberg, VIC, Australia
  3. Translational Research Institute, Queensland University of Technology, Buranda, VIC, Australia
  4. Department of Anatomical Pathology, Austin Health, Melbourne, Australia, Melbourne, Victoria
  5. Olivia Newton-John Cancer Research Institute, and School of Cancer Medicine, La Trobe University, Heidelberg, Victoria, Australia, Heidelberg, Victoria, Australia
  6. Department of Medicine, University of Melbourne, Melbourne, VIC, Australia

Prostate cancer remains one of the most prevalent cancers detected in males, but adequate

prognostic biomarkers that can distinguish between indolent and aggressive disease are currently

lacking. An inflamed tumour microenvironment can lead to the development of tertiary lymphoid

structures (TLS), which can mount adaptive effector and memory immune responses than can

inform patient outcomes. In functional TLS, B cells can undergo dynamic tumour antigen-driven

development into antibody-secreting cells (ASCs).

In this study, we aimed to develop in-house Opal™

-TSA multiplex immunohistochemistry panels

to adequately identify B cells, ASCs, and TLS, as well as characterise TLS based on their maturity.

We then used these panels to investigate their prognostic value in a prostate cancer cohort of 64

low- and high-grade individuals, using treatment naïve prostatectomy tissue sections.

We successfully developed two in-house mIHC panels, including a B cell and TLS panel. ASCs

were more commonly seen surrounding tumour areas (n=57/64 in peritumoural regions vs.

n=44/63 in intratumoural regions, chi-square p-value=0.0024). Interestingly, a third of specimens

lacked tumour-infiltrating ASCs (31%, n=20/64). ASCs were more abundant in patients with high-

grade disease when located in both intratumoural (64% low-grade vs. 79% high-grade, chi-square

p-value=0.0188) and peritumoural regions (87% low-grade vs. 100% high-grade, chi-square p-

value=0.0001). It was evident that most relapse patients contained abundant intratumoural ASCs

(70% of relapse vs. 26% of non-relapse patients, chi-square p-value=0.0248). When investigating

TLS, these were detected in most patient samples (73%, n=47/64), in both proximal and distal

tumour areas. TLS were mostly mature (92%, n=43/47), and often surrounded by ASCs. Mature

TLS were more abundantly seen in relapse patients (100% relapse vs. 90% non-relapse; chi-

square p-value=0.0012).

In conclusion, B cells and TLS in the tumour microenvironment of prostate cancer patients can

be used to distinguish between low- and high-grade disease and to predict the likelihood of

disease relapse.