Immunotherapy opens a new journey of bladder cancer diagnosis PD-L1 accurate interpretation is essential.

As the most common malignant tumor of urinary system, urothelial carcinoma (UC) is heterogeneous, and different histological subtypes have different pathological and molecular characteristics. The effect of traditional chemotherapy is limited, and patients are easy to relapse and metastasize, and the overall prognosis is poor [1].with more and more immunotherapeutic drugs, represented by PD-1 / PD-L1 immune checkpoint inhibitors, have been approved for the treatment of advanced or metastatic UC, breaking the bottleneck of diagnosis and treatment of UC for many years, and providing the possibility of long-term survival for UC patients.recently, Professor Zheng Yulong and Professor Teng Xiaodong, Department of Pathology, Department of oncology, First Affiliated Hospital of Medical College of Zhejiang University, shared online the new progress of immunotherapy for UC and the application and interpretation criteria of PD-L1 (sp263) detection in UC.chairman of the meeting, Professor Liu Yanhui, Department of Pathology, Guangdong Provincial People's Hospital, pointed out: "in recent years, immune checkpoint inhibitors have made positive progress in the treatment of UC and other tumors, providing more choices for clinical diagnosis and treatment, but also putting forward new requirements for pathological diagnosis.how to establish a unified and standardized PD-L1 detection system and interpretation criteria, to help clinical accurately assess the PD-L1 expression level of patients, so as to screen out potential immunotherapy beneficiaries has become a major topic for pathologists."the high expression of PD-L1 may become an important reference standard for primary and secondary immunotherapy of UC. At present, the risk of recurrence is still a challenge for non muscle invasive UC, with nearly 30% to 70% of superficial recurrence risk and 1% to 30% of disease progression to muscle invasive disease within 5 years [2].due to potential renal insufficiency, poor functional status or complications, up to 50% of patients with advanced UC should not be treated with cisplatin [2]."UC is easy to relapse in the early stage. Nearly half of the patients are intolerant to the first-line platinum drugs, and almost all patients will have disease progression. However, the second-line chemotherapy has no exciting survival improvement, which leads to the long-term systemic treatment dilemma of UC."Professor Zheng Yulong said," the emergence of immunotherapy has broken this dilemma and significantly improved the survival benefits of UC patients.it is worth noting that a number of clinical studies have shown that patients with high expression of PD-L1 show better efficacy in immunotherapy."a multicenter phase I / II open clinical study of durvalumab monotherapy for locally advanced or metastatic UC The results showed that the objective response rate (ORR) of PD-L1 high expression group was 27.6%, while that of PD-L1 low expression group was only 5.1%; the orr of PD-L1 high expression group was 27.4%, and that of PD-L1 low expression group was only 4.1%.[3] javelin bladder, a multicenter phase III randomized open trial of avelumab, was presented at the annual meeting of the American Society of Clinical Oncology (ASCO 2020) Among all patients with locally advanced or metastatic UC without progression to first-line platinum therapy, the median overall survival (OS) and progression free survival (PFS) of patients receiving avelumab maintenance therapy combined with best support therapy (BSC) were significantly better than those receiving only BSC. Among them, the patients with high expression of PD-L1 were more beneficial.[4] in addition, a number of clinical studies on neoadjuvant immunotherapy have been carried out in patients with muscle invasive bladder cancer (MIBC), and the expression level of PD-L1 shows a significant correlation with neoadjuvant drug response [5], which can be used as one of the markers for predicting the efficacy of MIBC.dutreneo published in ASCO 2020 The study found that the tumor was divided into two types according to tumor inflammation index (TIS), namely, cold and hot types. However, the expression level of PD-L1 could predict the efficacy of durvalumab combined with tremelimumab. The pT0 of patients with high expression of PD-L1 could reach 57.1%, while the patients with low expression of PD-L1 were only 14.3%.[6] Professor Zheng Yulong said: "the systematic treatment of UC is showing a multi-faceted development trend.among them, PD-1 / PD-L1 inhibitors have become one of the standard second-line treatments for locally advanced or metastatic UC.in recent years, the clinical data of immunotherapy combined with other drugs is also increasing, which indicates that it has the potential to become a new standard of first-line treatment. due to the high degree of malignancy and heterogeneity of UC, the same treatment strategy may not be applicable to all patients. Therefore, it is very important to select the appropriate benefit population through biomarker concomitant diagnosis to ensure the clinical treatment efficiency. "to establish a standardized PD-L1 detection and interpretation system to ensure the maximum benefit of UC patients. Research shows that the detection of PD-L1 expression level in tumor microenvironment can provide important reference information for immunotherapy targeting PD-1 / PD-L1 signal. the above-mentioned study 1108, javelin bladder 100 and dutreneo studies all used the Ventana PD-L1 (sp263) detection system. PD-L1 expression ≥ 25% on tumor cells (TC) or immune cells (IC) was used as the evaluation criteria for PD-L1 high expression, so as to screen out patients who can obtain the best clinical results. recently, Ventana PD-L1 (sp263) detection, which was approved based on clinical prospective studies based on Chinese data, became the first concomitant diagnosis of UC immunotherapy in China. Its detection system covers benchmark ultra automatic immunohistochemistry (IHC) staining platform, sp263 antibody, OptiView detection reagent and sp263 scoring algorithm. "concomitant diagnosis is a test that must be carried out when the patient receives the corresponding drug treatment. "Professor Teng Xiaodong pointed out," with the accompanying diagnosis of PD-L1 (sp263), pathologists need to establish corresponding standardized detection system, including laboratory quality control evaluation, interpretation standards, etc., to ensure the smooth development of UC immunotherapy in China. "PD-L1 (sp263) detection is suitable for formalin fixed, paraffin embedded (FFPE) UC tissues. After staining with benchmark automatic staining platform, the expression of PD-L1 protein in TC and tumor related IC was evaluated, and the proportion of tumor related IC in tumor area (ICP) was also evaluated. any staining or no staining results must be determined on the basis of histological morphology and control tissue evaluation, and evaluated by trained pathologists in combination with the patient's clinical history and other diagnostic test results. figure: PD-L1 (sp263) is used as the standard for the diagnosis of UC. It should be noted that TC staining is usually manifested as peri annular membrane staining. Any intensity or pattern of membrane staining, partial or complete peripheral membrane staining (as long as the tumor cell membrane is outlined) should be included in the TC score, but cytoplasmic staining is not included in the evaluation. figure: UC PD-L1 (sp263) staining: TC positive rate ≥ 25%, IC staining showed weak to strong cell membrane and / or weak cytoplasmic staining, showing punctate staining. IC includes lymphocytes, macrophages, dendritic cells, neutrophils, plasma cells and histiocytes. figure: UC PD-L1 (sp263) staining: positive rate of tumor related IC ≥ 25%, Professor Teng Xiaodong shared some difficult cases that may appear in UC tissue interpretation, and gave solutions: 1. Weak TC membrane staining and weak TC plasma staining: observe and distinguish through higher power field of vision; figure: observe and evaluate through high power field of vision; 2. Overlap of strong TC staining and IC staining: H & amp; should be used; 2; E-staining was used to confirm the presence of IC infiltrating the tumor, and the pattern of PD-L1 staining and nuclear morphology were used to confirm whether IC (punctate staining, small homogeneous nuclei) or TC (linear membrane staining, large irregular nuclei) staining were used; 3. PD-L1 staining cases close to the critical value: the whole tumor area was evaluated by high-power vision, and discussed with experienced colleagues if necessary; 4. Multiple tissue components Results: the composition of UC samples produced by transurethral resection (turb) is complex. Multiple tissue fragments scattered on the slide may be accompanied by varying amounts of necrosis, crush / burn artifacts, live TC and / or tumor related IC. at this time, it is necessary to estimate the staining percentage of each tissue segment, and then obtain the overall average value; 5. Endogenous pigments are confused with IC and TC: sometimes, endogenous substances (such as melanin or hemosiderin) may mask and interfere with the interpretation of PD-L1 staining. the comparison between negative control slide and PD-L1 staining slide can help distinguish biomarker staining from endogenous substance, and non-specific staining can also be seen on PD-L1 stained slide in necrotic area. Professor Teng Xiaodong concluded: "PD-L1 expression in UC patients is highly heterogeneous. Weak TC membrane staining, overlapping of strong TC staining and IC staining, and PD-L1 staining at the boundary may occur in the film reading, which brings great challenges to the interpretation of the results. Pathologists should make full use of laboratory equipment, carefully distinguish different tissues, and accumulate reading experience to accurately detect and interpret UC To provide reliable basis for clinical decision-making. [1] braicu C, cojocneanu Petric R, Chira s, et al. Int j nanomedicine. 2015; 10:791-800. [2] Karthik V giridhar, et al. Mayo Clin proc. 2017 Oct; 92 (10) 1564-1582. [3] Bowles T, et al. JAMA Oncol. 2017 SEP 14; 3(9):e172411. [4]ASCO 2020: JAVELIN Bladder 100 Phase III Results: Maintenance Avelumab + Best Supportive Case vs BSC Alone After Platinum-Based First-Line Chemotherapy in Advanced Urothelial Carcinoma[5]Li R, Spiess PE, Gilbert SM, Necchi A. Eur Urol. 2019; 76(1) 4-6.[6]ASCO 2020: DUTRENEO Trial: A Randomized Phase II Trial of DUrvalumab and TREmelimumab Versus Chemotherapy as a NEOadjuvant Approach to Muscle-Invasive Urothelial Bladder Cancer Patients Prospectively Selected by an Interferon-Gamma Immu