Predicting Response to Neoadjuvant Chemotherapy in Muscle-invasive Bladder Cancer

Bladder cancer (BC) is the 10th most commonly diagnosed cancer worldwide and the second most common cancer among Egyptian males. The mainstay of treatment of muscle-invasive BC( MIBC) is neoadjuvant chemotherapy (NAC) followed by radical cystectomy (RC) or bladder preservation(BP) using maximal transurethral resection of the bladder tumor followed by chemoradiation. The rationale to use NAC before RC or BP is to eradicate micro-metastasis and to downstage the primary tumor. The 5-year cancer-specific survival for responders to NAC is 90%, in contrast to 30-40% for those not obtaining an objective response. Drawbacks of NAC are disappointing delay of surgery in non-responders and the potential toxicity. So, predictors of response to NAC are necessary to identify patients who may achieve pathologic complete response and will benefit from BP, and the others who may not respond to NAC and spare them NAC toxicity and RC delay. Tumor microenvironment (TME), including neutrophil extracellular traps (NETs), and CD8+ T lymphocytes is a promising predictor of response to NAC in MIBC. NETs are reticulated DNA structures decorated with various protein substances (e.g., histones, myeloperoxidase, neutrophil elastase).NETs are involved in tumor growth, metastasis, and treatment resistance. Moreover, NETs can inhibit T cell responses, thereby promoting tumor growth. On the other hand, immune cells that are present in the TME play a major role in slowing down tumor progression. CD8+T lymphocytes play a central role in immune-mediated control of cancer . Also, they have been found to be a prognostic tool for advanced BC.

Formalin fixed paraffin embedded tissue specimen of the baseline TUR of MIBC will be obtained from pathology laboratory, Pathology Department, Assiut University. * Histological diagnosis of H\&E stained sections will be confirmed. * Immunohistochemical staining for Citrullinated histone H3 (H3Cit) antibody as a hallmark of NETs, and CD8 antibody to quantity density of NETs and CD8 expression, then calculate NETs/CD8 ratio. * Baseline clinicopathological features of MIBC patients who received neoadjuvant chemotherapy will be collected from patients' records. * Correlation between NETs expression, CD8 expression, NETs/CD8 ratio, and the baseline clinicopathological features with the response to neoadjuvant chemotherapy. * develop a risk score based on the significant predictors of response to identify patients who may achieve pathologic complete response and will benefit from BP, and the others who may not respond to NAC and spare them NAC toxicity and RC delay.