PBRM1 mutations might render a subtype of biliary tract cancers sensitive to drugs targeting the DNA damage repair system

Understanding homologous recombination repair deficiency in biliary tract cancers: clinical implications and correlation with platinum sensitivity

BACKGROUND

Biliary tract cancers (BTCs) exhibit high mortality rates and significant heterogeneity in both clinical and molecular characteristics. This study aims to molecularly characterize a cohort of patients with BTC, with a specific focus on genomic alterations within homologous recombination repair (HRR) genes in a real-world setting.

PATIENTS AND METHODS

We carried out a retrospective analysis on 256 patients with BTC treated at five Austrian centers and one German comprehensive cancer center between 2016 and 2023 utilizing comprehensive genomic profiling platforms to assess HRR status and its correlation with clinical outcomes after platinum-based chemotherapy.

RESULTS

A total of 67 patients (27.5%) exhibited HRR gene mutations (HRRm), with the most common pathogenic alterations in BAP1 (9%), ARID1A (7.8%), and ATM (6.1%). Time to failure of the first-line strategy (TFS) between patients with HRRm and non-HRRm treated with platinum agents was 7.9 and 6.7 months, respectively [hazard ratio (HR) 0.89; P = 0.49]. The overall survival (OS) estimates at 6, 18, and 24 months were 82%, 45%, and 39% in the HRRm group (median 16.01 months) and 81%, 42%, and 22% in the HRR group (median 15.68 months), respectively (Fleming-Harrington test P = 0.0004; log-rank P = 0.022). Significance did not persist in the multivariate analysis (HR 0.72; 95% confidence interval 0.489-1.059; P = 0.095). An interaction between HRRm status and molecular-informed therapeutic strategies in later lines was noted. In the second-line treatment, OS following an irinotecan-based regimen was comparable to re-exposure to platinum-based agents (12.36 versus 10.13 months; HR 0.92; P = 0.85). No better outcome was noted for patients with HRRm versus patients with non-HRRm with second-line platinum agents (HR 1.45; P = 0.35).

CONCLUSIONS

Patients with HRRm with BTC showed a potential advantage in OS following platinum-based first-line chemotherapy, presumably attributed to enhanced opportunities for targetable coalterations. Further investigation is needed to outline HRR within the scope of BTCs and detail a clinically meaningful sensitivity to platinum agents or targeted approaches with poly (ADP-ribose) polymerase (PARP) inhibitors.

The Genomic, Transcriptomic, and Immunologic Landscape of HRAS Mutations in Solid Tumors

Tipifarnib is the only targeted therapy breakthrough for HRAS-mutant (HRASmt) recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). The molecular profiles of HRASmt cancers are difficult to explore given the low frequency of HRASmt. This study aims to understand the molecular co-alterations, immune profiles, and clinical outcomes of 524 HRASmt solid tumors including urothelial carcinoma (UC), breast cancer (BC), non-small-cell lung cancer (NSCLC), melanoma, and HNSCC. HRASmt was most common in UC (3.0%), followed by HNSCC (2.82%), melanoma (1.05%), BC (0.45%), and NSCLC (0.44%). HRASmt was absent in Her2+ BC regardless of hormone receptor status. HRASmt was more frequently associated with squamous compared to non-squamous NSCLC (60% vs. 40% in HRASwt, p = 0.002). The tumor microenvironment (TME) of HRASmt demonstrated increased M1 macrophages in triple-negative BC (TNBC), HNSCC, squamous NSCLC, and UC; increased M2 macrophages in TNBC; and increased CD8+ T-cells in HNSCC (all p < 0.05). Finally, HRASmt was associated with shorter overall survival in HNSCC (HR: 1.564, CI: 1.16-2.11, p = 0.003) but not in the other cancer types examined. In conclusion, this study provides new insights into the unique molecular profiles of HRASmt tumors that may help to identify new targets and guide future clinical trial design.

Targeting ATR in patients with cancer

Pharmacological inhibition of the ataxia telangiectasia and Rad3-related protein serine/threonine kinase (ATR; also known as FRAP-related protein (FRP1)) has emerged as a promising strategy for cancer treatment that exploits synthetic lethal interactions with proteins involved in DNA damage repair, overcomes resistance to other therapies and enhances antitumour immunity. Multiple novel, potent ATR inhibitors are being tested in clinical trials using biomarker-directed approaches and involving patients across a broad range of solid cancer types; some of these inhibitors have now entered phase III trials. Further insight into the complex interactions of ATR with other DNA replication stress response pathway components and with the immune system is necessary in order to optimally harness the potential of ATR inhibitors in the clinic and achieve hypomorphic targeting of the various ATR functions. Furthermore, a deeper understanding of the diverse range of predictive biomarkers of response to ATR inhibitors and of the intraclass differences between these agents could help to refine trial design and patient selection strategies. Key challenges that remain in the clinical development of ATR inhibitors include the optimization of their therapeutic index and the development of rational combinations with these agents. In this Review, we detail the molecular mechanisms regulated by ATR and their clinical relevance, and discuss the challenges that must be addressed to extend the benefit of ATR inhibitors to a broad population of patients with cancer.

PBRM1 presents a potential ctDNA marker to monitor response to neoadjuvant chemotherapy in cervical cancer

Neoadjuvant chemotherapy (NACT) is a therapeutic option for locally advanced cervical cancer (LACC) patients. This study was aimed to identify potential liquid biopsy biomarkers to monitor the NACT response. Through targeted next-generation sequencing (NGS) analysis of circulating tumor DNA (ctDNA) and tumor tissue DNA (ttDNA) taken from LACC patients undergoing platinum-based NACT, 64 genes with mutations emerge during NACT in the non-responders but none in the responders. Among them, the PBRM1, SETD2, and ROS1 mutations were frequently detected in the ctDNA and ttDNA of the non-responders, and mutant PBRM1 was associated with poorer survival of patients. In vitro, PBRM1 knockdown promoted resistance to cisplatin through boosting STAT3 signaling in cervical cancer cells, while it sensitized tumor cells to poly-ADP-ribose-polymerase inhibitor olaparib. These findings suggest that mutant PBRM1 is a potential ctDNA marker of emerging resistance to NACT and of increased sensitivity to olaparib, which warrants further clinical validation.

New trends in diagnosis and management of gallbladder carcinoma

Gallbladder (GB) carcinoma, although relatively rare, is the most common biliary tree cholangiocarcinoma with aggressiveness and poor prognosis. It is closely associated with cholelithiasis and long-standing large (> 3 cm) gallstones in up to 90% of cases. The other main predisposing factors for GB carcinoma include molecular factors such as mutated genes, GB wall calcification (porcelain) or mainly mucosal microcalcifications, and GB polyps ≥ 1 cm in size. Diagnosis is made by ultrasound, computed tomography (CT), and, more precisely, magnetic resonance imaging (MRI). Preoperative staging is of great importance in decision-making regarding therapeutic management. Preoperative staging is based on MRI findings, the leading technique for liver metastasis imaging, enhanced three-phase CT angiography, or magnetic resonance angiography for major vessel assessment. It is also necessary to use positron emission tomography (PET)-CT or 18F-FDG PET-MRI to more accurately detect metastases and any other occult deposits with active metabolic uptake. Staging laparoscopy may detect dissemination not otherwise found in 20%-28.6% of cases. Multimodality treatment is needed, including surgical resection, targeted therapy by biological agents according to molecular testing gene mapping, chemotherapy, radiation therapy, and immunotherapy. It is of great importance to understand the updated guidelines and current treatment options. The extent of surgical intervention depends on the disease stage, ranging from simple cholecystectomy (T1a) to extended resections and including extended cholecystectomy (T1b), with wide lymph node resection in every case or IV-V segmentectomy (T2), hepatic trisegmentectomy or major hepatectomy accompanied by hepaticojejunostomy Roux-Y, and adjacent organ resection if necessary (T3). Laparoscopic or robotic surgery shows fewer postoperative complications and equivalent oncological outcomes when compared to open surgery, but much attention must be paid to avoiding injuries. In addition to surgery, novel targeted treatment along with immunotherapy and recent improvements in radiotherapy and chemotherapy (neoadjuvant-adjuvant capecitabine, cisplatin, gemcitabine) have yielded promising results even in inoperable cases calling for palliation (T4). Thus, individualized treatment must be applied.

Mesothelin expression correlates with elevated inhibitory immune activity in patients with colorectal cancer

The expression of the protein Mesothelin (MSLN) is highly variable in several malignancies including colorectal cancer (CRC) and high levels are associated with aggressive clinicopathological features and worse patient survival. CRC is both a common and deadly cancer; being the third most common in incidence and second most common cause of cancer related death. While systemic therapy remains the primary therapeutic option for most patients with stage IV (metastatic; m) CRC, their disease eventually becomes treatment refractory, and 85% succumb within 5 years. Microsatellite-stable (MSS) CRC tumors, which affect more than 90% of patients with mCRC, are generally refractory to immunotherapeutic interventions. In our current work, we characterize MSLN levels in CRC, specifically correlating expression with clinical outcomes in relevant CRC subtypes and explore how MSLN expression impacts the status of immune activation and suppression in the peritumoral microenvironment. High MSLN expression is highly prevalent in CMS1 and CMS4 CRC subtypes as well as in mCRC tissue and correlates with higher gene mutation rates across the patient cohorts. Further, MSLN-high patients exhibit increased M1/M2 macrophage infiltration, PD-L1 staining, immune-inhibitory gene expression, enrichment in inflammatory, TGF-β, IL6/JAK/STAT3, IL2/STAT5 signaling pathways and mutation in KRAS and FBXW7. Together, these results suggest MSLN protein is a potential target for antigen-specific therapy and supports investigation into its tumorigenic effects to identify possible therapeutic interventions for patients with high MSLN expressing MSS CRC.

Fibrolamellar hepatocellular carcinoma: a case report and gene analysis

BACKGROUND

Fibrolamellar hepatocellular carcinoma (HCC) (FL-HCC) is rare in Japan. FL-HCC develops in young patients with no history of cirrhosis and tends to manifest lymphatic metastasis with clinical features similar to those of HCC. We present a case of FL-HCC in a young male patient.

CASE PRESENTATION

A 14-year-old male patient underwent abdominal computed tomography (CT) to diagnose appendicitis, wherein a hepatic tumor was detected. Dynamic enhanced CT revealed a 35-mm solid tumor, which contrasted at the early phase of dynamic enhanced study of the right hepatic segments, with occlusion of the right portal vein. We performed right hepatectomy for these lesions. The patient experienced a single lymphatic recurrence on the hepatoduodenal ligament 12 months after the initial surgery. We performed lymphadenectomy for the recurrent tumor. We performed RNA sequencing (RNA-seq) and targeted DNA sequencing of the resected specimens (primary tumor, lymphatic metastasis, and normal liver). RNA-seq detected DNAJB1-PRKACA in both primary and metastatic lesions as previously reported. Furthermore, The Cancer Genome Atlas (TCGA) database was used to compare other gene expressions in this case with those of previously reported cases of FL-HCC and HCC in young patients. Principal component analysis of differentially expressed genes in the top 10% revealed that the gene expression in our case was similar to that of previous FL-HCC cases but was a different cluster from that in HCC cases in young patients. Mutational analysis did not detect any somatic mutations associated with carcinogenesis, including previously reported mutations (Kastenhuber et al. in Proc Natl Acad Sci USA 114: 13076-84, 2017).

CONCLUSION

We encountered a case of FL-HCC, a rare hepatic tumor in an adolescent patient, and evaluated the genetic background. Our findings could contribute to the elucidation of the mechanisms underlying carcinogenesis and progression in patients with FL-HCC and thereby contribute to the development of new therapeutic strategies in the future that may improve patient prognosis.