Expression of p53 Protein Associates with Anti-PD-L1 Treatment Response on Human-Derived Xenograft Model of GATA3/CR5/6-Negative Recurrent Nonmuscular Invasive Bladder Urothelial Carcinoma

Background: The possible involvement of p53 signaling, FGFR3 expression, and FGFR3 mutation rates in the prediction of the NMIBC anti-PD-L1 treatment response needs to be clarified. The main aim of our study was to explore predictive value of p53 expression, FGFR3 expression, and its gene mutation status for the therapeutic success of anti-PD-L1 treatment in the patient-derived murine model of recurrent high-PD-L1(+) GATA3(-)/CR5/6(-) high-grade and low-grade NMIBC. Methods: twenty lines of patient-derived xenografts (PDXs) of relapsed high-PD-L1(+) double-negative NMIBC were developed, of which 10 lines represented high-grade tumors and the other ones—low-grade bladder cancer. Acceptors of each grade-related branch received specific anti-PD-L1 antibodies. Animals’ survival, tumor-doubling time, and remote metastasis were followed during the post-interventional period. PD-L1, GATA3, CR5/6, and p53 protein expressions in engrafted tumors were assessed by immunohistochemistry. The FGFR3 expression and FGFR3 mutations in codons 248 and 249 were detected by real-time polymerase chain reaction. Results: The expression of p53 protein is an independent factor affecting the animals’ survival time [HR = 0.036, p = 0.031] of anti-PD-L1-treated mice with low-grade high-PD-L1(+) double-negative NMIBC PDX. The FGFR3 expression and FGFR3 mutation rate have no impact on the anti-PD-L1 treatment response in the interventional groups. Conclusions: p53 expression may be considered as a prognostic factor for the anti-PD-L1 treatment efficacy of low-grade high-PD-L1-positive GATA3(-)/CR5/6(-)-relapsed noninvasive bladder cancer.

Case Report: Anlotinib Combined With Sintilimab as Third-Line Treatment in a Metastatic Urothelial Bladder Carcinoma Patient With FGFR3 Mutation

We report on a case of metastatic urothelial bladder carcinoma (mUBC) treated with anlotinib combined with sintilimab. A 69-year-old male was diagnosed with non-muscle invasive bladder cancer (NMIBC). He received transurethral resection of bladder tumor (TURBT) and intravesical gemcitabine chemotherapy. After the patients’ cancer progressed to mUBC, cisplatin-based chemotherapy (gemcitabine combined with cisplatin, GC) was performed to this patient as first line therapy for four cycles. However, the disease progressed again within 6 months. Local radiotherapy was performed on the metastatic lesions, and after radiotherapy, the patient received anti-PD-1 antibody (sintilimab 200 mg, q3w)combined with Albumin-bound (Nab)-paclitaxel (100 mg, qw) as the second-line therapy, but the patient’s cancer was still observed to be progressing. Molecular characterization confirmed the presence of FGFR3 mutations in the patient. Anlotinib was recommended to this patient. After the patient was fully informed and he was aware of off-label use of the drug, then, Nab-paclitaxel was replaced by anlotinib (10 mg D1–14, q3w) and sintilimab infusions were maintained for every 3 weeks. Partial response (PR) was observed through imaging examinations and stable disease (SD) was observed for more than 11 months; the patient’s quality of life also improved. This case suggested that anlotinib combined with sintilimab may be a safe and effective choice in the treatment of mUBC in patients with FGFR3 mutations.

Acute Myelogenous Leukemia Associated with MLL-SEPT6 Rearrangement and TRAF3, FGFR3 Mutation: A Pediatric Case Report and Review of the Literature

The MLL gene is a site of frequent rearrangement in acute leukemia with multiple fusion partners, but MLL-SEPT6 rearrangement is rare in clinical leukemia practice, and only 13 cases have been reported. We describe the case of an acute myelogenous leukemia child with MLL-SEPT6 rearrangement whose age of onset and accompanying gene mutations differs from previous reports. Considering the poor prognosis of leukemia children with MLL-SEPT6 rearrangement and the unsatisfactory results of existing treatments, the study of this case may provide new theories for diagnosis and treatment of MLL-SEPT6-associated childhood acute leukemia.

Bladder Cancer Tissue-Based Biomarkers

This review aims to provide a practical update regarding the current role of tissue-based biomarkers in bladder cancer. Their prognostic and predictive role both in non-muscle-invasive (NMIBC) and in muscle-invasive disease (MIBC) has been reviewed with particular focus to their use in clinical practice. In summary, the literature on the prediction of disease recurrence in NMIBC is inconclusive, and there is little information on prediction of response to intravesical bacillus Calmette-Guerin (BCG). Concerning disease progression, external prospective validation studies suggest that FGFR3 mutation status and gene signatures may improve models that are based only on clinicopathologic information. In MIBC, tissue-based biomarkers are increasingly important, since they may predict the response to systemic chemotherapy and immunotherapy. In particular, the advent of molecular characterization promises to revolutionize the paradigm of decision-making in the treatment of MIBC. Molecular subtyping has been shown to improve the prediction of pathological stage at RC and to predict the response to systemic chemotherapy and immunotherapy. However, external and prospective validations are warranted to confirm these preliminary findings. Several different tissue-based biomarkers such as PD-1/PD-L1 expression, tumor mutational burden, and the analysis of tumor microenvironment, may in future play a role in selecting patients for systemic immunotherapy. However, to date, no pretreatment recommendations can be definitively made on the basis of any molecular predictors. In conclusion, despite the potential of tissue-based biomarkers, their use in bladder cancer should be limited to experimental settings.

MSK-ACCESS for the detection of fibroblast growth factor receptor-3 (FGFR3) mutations in plasma cell-free (cf)DNA of metastatic urothelial carcinoma (mUC) patients (pts) pre- and on erdafitinib (erda) therapy.

e17034 Background: The pan-FGFR inhibitor erda was recently FDA-approved for pretreated mUC pts harboring FGFR2/3 alterations. We explored concordance of FGFR3 mutation profiles between the primary tumor and cfDNA using the MSK-ACCESS platform. We also correlated changes in FGFR3 cfDNA mutant allele fraction (MAF) with response to drug. Methods: Plasma samples were collected from mUC pts started on erda at baseline, on treatment (tx), and at progression. Demographic and clinical characteristics were obtained. Baseline tumors were sequenced with MSK-IMPACT (ref) and plasma samples were sequenced using MSK-ACCESS, a cfDNA platform that sequences 129 genes using unique molecular indexes to generate > 15,000x coverage and detection of somatic mutations down to 0.1% MAF. Results: Between 08/2019-1/2020, 11 pts received erda 8mg daily. Of these, 3 pts increased dose to 9mg daily based on phosphorus level, 4 required dose reductions and 6 dose interruptions. In 5 pts, erda was discontinued for disease progression. FGFR3 S249C was the most frequent alteration detected (64%) followed by Y373C (18%), R248C and S371C (both 9%). Pre-treatment plasma FGFR3 profiles were concordant with tissue in 91% (10/11) of pts and additional FGFR3 mutations were detected in 3 cases (27%, Table), including 1 pt with an FGFR3-TACC3 fusion and hotspot mutations only in cfDNA. In 2 responding pts, the mutant allele was undetectable on erda. Conclusions: A high degree of concordance between primary tumor and cfDNA FGFR3 mutation detection was observed. FGFR3 mutations exclusive to cfDNA were found in a subset of pts. Further pt accrual and follow-up are ongoing to assess for correlations between erda response and tx-related changes in cfDNA MAF, and to assess whether cfDNA can identify resistance mechanisms. [Table: see text]

Pure Large Nested Variant of Urothelial Carcinoma (LNUC) Is the Prototype of an FGFR3 Mutated Aggressive Urothelial Carcinoma with Luminal-Papillary Phenotype

Since 2016, large nested urothelial carcinoma (LNUC) has been included within the WHO classification of urothelial tumors. Limited reports with mainly small case series have confirmed the malignant behavior of LNUC despite its bland morphological appearance. We evaluated, for the first time, markers for new immunooncological or targeted therapies including FGFR3 mutational status and PD-L1 status, the frequency of TERT-promoter mutations and the molecular subtype in a cohort of 25 LNUC using SNaPshot analysis and immunohistochemistry. Of the 25 cases, 17 were pure LNUC, with 13 showing an additional exophytic papillary/papillary-like component. Seven mixed LNUCs presented areas of classical nested variant urothelial carcinoma (NVUC) and one showed a component of conventional urothelial carcinoma. Of the 17 evaluable pure LNUCs, 16 were FGFR3-mutated with identical mutations in their concomitant papillary/papillary-like components. An FGFR3 mutation was found in 1/7 evaluable mixed LNUCs combined with NVUC. TERT-promoter mutations were detected in 86.7% pure and 83.3% mixed tumors. Immunohistochemistry revealed a luminal phenotype; PD-L1 was negative in the majority of tumor cells and tumor-associated immune cells. Pure LNUC is a prime example of a luminal, FGFR3-mutated, mostly PD-L1-negative tumor. In contrast, FGFR3 mutations seem to be rare in mixed LNUC, which may indicate a different pathway of tumor development.

A novel ultra-sensitive urine based FGFR3 mutation assay for diagnosis and recurrence detection of non-muscle-invasive bladder cancer (NMIBC) – Design of the Urodiag® Kit

Background We have recently developed a highly accurate urine-based test, named Urodiag ® , associating FGFR3 mutation and DNA methylation assays for recurrence surveillance in patients with low-, intermediate-, and high-risk NMIBC. Previously, the detection of four FGFR3 mutations (G372C, R248C, S249C and Y375C) required the amplification steps and the PCR products were analyzed by capillary electrophoresis (Allele Specific-PCR, AS-PCR), which was expensive and time-consuming. Here, we present the development a novel ultra-sensitive multiplex PCR assay as called “Mutated Allele Specific Oligonucleotide-PCR (MASO-PCR)”, generating cost-effective, simple, fast and clinically applicable assay for the detection of FGFR3 mutations in voided urine. Methods Comparative clinical performances of MASO-PCR and AS-PCR technologies were performed from 263 urine DNA samples (87 FGFR3 mutated and 176 FGFR3 wild type). In the development of Urodiag ® Kit, we studied the stability and reproducibility of each all-in-one PCR master mix (single reaction mixture including all the necessary PCR components) for MASO-PCR and QM-MSPCR (Quantitative Multiplex Methylation-Specific PCR to co-amplify SEPTIN9, HS3ST2 and SLIT2 methylated genes) assays. Results Complete concordance (100%) was observed between the MASO-PCR and AS-PCR results. Each PCR master mix displayed excellent reproducibility and stability after 12 months of storage at -20°C, with intra-assay standard deviations lower than 0.3 Ct and coefficient of variations (CV) lower than 1%. The limit of detection (LoD) of MASO-PCR was 5% mutant detection in a 95% of wild-type background. The limit of quantification (LoQ) of QM-MSPCR was 10 pg of bisulfite-converted DNA. Conclusions We developed and clinically validated the MASO-PCR assay, generating cost-effective, simple, fast and clinically applicable assay for the detection of FGFR3 mutations in urine. We also designed the Urodiag ® Kit, which includes the MASO-PCR and QM-MSPCR assays. Adapted to routine clinical laboratory (simplicity, accuracy), the kit will be a great help to urologists for recurrence surveillance in patients at low-, intermediate- and high-risk NMIBC. Reducing the number of unnecessary cystoscopies, it will have extremely beneficial effects for patients (painless) and for the healthcare systems (low cost).