Complete Response To Tislelizumab In A Muscle-Invasive Urothelial Carcinoma After Surgery Associated With Tumor Mutational Burden High: A Case Report

Muscle-invasive urothelial carcinoma (MIUC) is a highly aggressive urothelial carcinoma. Radical cystectomy (RC) is standard of treatment, but still more than 50% patients with cancer invading the muscularis propria or involving the regional lymph nodes will have metastatic recurrence. In CheckMate274 study, programmed cell death-1 (PD-1) inhibitor nivolumab as adjuvant treatment has shown effective for patients with MIUC. Tislelizumab is an anti-human PD-1 monoclonal IgG4 antibody which was specifically engineered to minimize FcɣR macrophage binding to abrogate antibody-dependent phagocytosis. But there is no report of tislelizumab as adjuvant treatment in MIUC currently. Here, we report a case of MIUC in a patient with PD-L1-negative, microsatellite stable (MSS), high tumor mutational burden (TMB-H) obtained complete response (CR) receiving tislelizumab therapy after surgery. Progression-free survival (PFS) exceeded 6 months since tislelizumab treatment. To our knowledge, this is the first reported case of MIUC patient with PD-L1-negative, MSS and TMB-H who responded well to tislelizumab as adjuvant treatment. However, we still need more studies to assess the efficacy of tislelizumab as adjuvant treatment in MIUC and to confirm that TMB is a predicted biomarker of tislelizumab for efficacy.

The Role of Recombinant AAV in Precise Genome Editing

The replication-defective, non-pathogenic, nearly ubiquitous single-stranded adeno-associated viruses (AAVs) have gained importance since their discovery about 50 years ago. Their unique life cycle and virus-cell interactions have led to the development of recombinant AAVs as ideal genetic medicine tools that have evolved into effective commercialized gene therapies. A distinctive property of AAVs is their ability to edit the genome precisely. In contrast to all current genome editing platforms, AAV exclusively utilizes the high-fidelity homologous recombination (HR) pathway and does not require exogenous nucleases for prior cleavage of genomic DNA. Together, this leads to a highly precise editing outcome that preserves genomic integrity without incorporation of indel mutations or viral sequences at the target site while also obviating the possibility of off-target genotoxicity. The stem cell-derived AAV (AAVHSCs) were found to mediate precise and efficient HR with high on-target accuracy and at high efficiencies. AAVHSC editing occurs efficiently in post-mitotic cells and tissues in vivo. Additionally, AAV also has the advantage of an intrinsic delivery mechanism. Thus, this distinctive genome editing platform holds tremendous promise for the correction of disease-associated mutations without adding to the mutational burden. This review will focus on the unique properties of direct AAV-mediated genome editing and their potential mechanisms of action.

Secretory Autophagy Forges a Therapy Resistant Microenvironment in Melanoma

Melanoma is the most aggressive skin cancer characterized by high mutational burden and large heterogeneity. Cancer cells are surrounded by a complex environment, critical to tumor establishment and progression. Thus, tumor-associated stromal components can sustain tumor demands or impair cancer cell progression. One way to manage such processes is through the regulation of autophagy, both in stromal and tumor cells. Autophagy is a catabolic mechanism that provides nutrients and energy, and it eliminates damaged organelles by degradation and recycling of cellular elements. Besides this primary function, autophagy plays multiple roles in the tumor microenvironment capable of affecting cell fate. Evidence demonstrates the existence of novel branches in the autophagy system related to cytoplasmic constituent’s secretion. Hence, autophagy-dependent secretion assembles a tangled network of signaling that potentially contributes to metabolism reprogramming, immune regulation, and tumor progression. Here, we summarize the current awareness regarding secretory autophagy and the intersection with exosome biogenesis and release in melanoma and their role in tumor resistance. In addition, we present and discuss data from public databases concerning autophagy and exosome-related genes as important mediators of melanoma behavior. Finally, we will present the main challenges in the field and strategies to translate most of the pre-clinical findings to clinical practice.

Primary Hepatoid Adenocarcinoma of Gallbladder With MB21D2/GALNT12/ARID2 Mutations: A Case Report

BackgroundPrimary hepatoid adenocarcinoma of the gallbladder is a relatively rare type of extrahepatic adenocarcinoma. The genetic changes involved in this type of adenocarcinoma were unexplained so far. We reported a rare case of primary hepatoid adenocarcinoma of gallbladder with Mab-21 domain containing 2 (MB21D2), polypeptide N-acetylgalactosaminyltransferase 12 (GALNT12), and AT-rich interaction domain 2 (ARID2) mutations, which was confirmed after surgical resection pathologically.Case SummaryA 69-year-old female with distention of hypogastrium and constipation received enema treatment, but ineffectively. No abnormalities were found on relevant physical examination. Then, the CT and MRI demonstrated a 3.3–4-cm soft tissue mass shadow in the neck of the gallbladder. The primary lesions consisted of two components: high-grade intraepithelial neoplasia of glands and hepatoid glands microscopically after laparoscope cholecystectomy. Immunohistochemical staining showed the sameness and difference of the two areas. Furthermore, tumor mutational burden (TMB) shows that the MB21D2, GALNT12, and ARID2 genes were mutated.ConclusionThis is the first report of primary hepatoid adenocarcinoma of the gallbladder with MB21D2, GALNT12, and ARID2 mutations. This will provide a theoretical basis for genetic changes in rare tumors.

Intraventricular Meningiomas: Clinical-Pathological and Genetic Features of a Monocentric Series

Intraventricular meningiomas (IVMs) are rare (0.5–5%) and usually low-grade (90% grade I) brain neoplasms. Their recurrence rate is lower than that of extra-axial meningiomas, but their surgical resection can be burdened with life-threatening complications, which represent the major cause of the reported 4% mortality. The aim of this study is to characterize the molecular portrait of IVMs to identify potential therapeutic targets. For this, we explored mutations and copy number variations (CNV) of 409 cancer-related genes and tumor mutational burden (TMB) of six cases, using next-generation sequencing. Five IVMs were grade I and one was grade II; none recurred, in spite of partial surgical resection in one case. NF2 mutation was the only recurring alteration and was present in three of the six IVMs, in association with SMARCB1 mutation in one case. None of the cases was hypermutated (TMB > 10 mutations/Mb). NF2-mutant progressing or recurring IVMs could potentially be treated with targeted therapies applied to other NF2-mutant tumors, as an alternative to surgery or radiosurgery, while in view of their low TMB they are unlikely candidates to immune check-point inhibition.