Contemporary Tailored Oncology Treatment of Biliary Tract Cancers

KRAS Allelic Variants in Biliary Tract Cancers

Importance

Biliary tract cancers (BTCs) contain several actionable molecular alterations, including FGFR2, IDH1, ERBB2 (formerly HER2), and KRAS. KRAS allelic variants are found in 20% to 30% of BTCs, and multiple KRAS inhibitors are currently under clinical investigation.

Objectives

To describe the genomic landscape, co-sequence variations, immunophenotype, genomic ancestry, and survival outcomes of KRAS-mutated BTCs and to calculate the median overall survival (mOS) for the most common allelic variants.

Design, Setting, and Participants

This retrospective, multicenter, pooled cohort study obtained clinical and next-generation sequencing data from multiple databases between January 1, 2017, and December 31, 2022. These databases included Princess Margaret Cancer Centre, MD Anderson Cancer Center, Foundation Medicine, American Association for Cancer Research Project GENIE, and cBioPortal for Cancer Genomics. The cohort comprised patients with BTCs who underwent genomic testing.

Main Outcome and Measure

The main outcome was mOS, defined as date of diagnosis to date of death, which was measured in months.

Results

A total of 7457 patients (n = 3773 males [50.6%]; mean [SD] age, 63 [5] years) with BTCs and genomic testing were included. Of these patients, 5813 had clinical outcome data available, in whom 1000 KRAS-mutated BTCs were identified. KRAS allelic variants were highly prevalent in perihilar cholangiocarcinoma (28.6%) and extrahepatic cholangiocarcinoma (36.1%). Thirty-six KRAS allelic variants were identified, and the prevalence rates in descending order were G12D (41%), G12V (23%), and Q61H (8%). The variant G12D had the highest mOS of 25.1 (95% CI, 22.0-33.0) months compared with 22.8 (95% CI, 19.6-31.4) months for Q61H and 17.8 (95% CI, 16.3-23.1) months for G12V variants. The majority of KRAS-mutated BTCs (98.9%) were not microsatellite instability-high and had low tumor mutational burden (ranging from a median [IQR] of 1.2 (1.2-2.5) to a mean [SD] of 3.3 [1.3]). Immune profiling through RNA sequencing of KRAS and NRAS-mutated samples showed a pattern toward a more immune-inflamed microenvironment with higher M1 macrophage activation (0.16 vs 0.12; P = .047) and interferon-γ expression compared with wild-type tumors. The G12D variant remained the most common KRAS allelic variant in all patient ancestries. Patients with admixed American ancestry had the highest proportion of G12D variant (45.0%).

Conclusions and Relevance

This cohort study found that KRAS allelic variants were relatively common and may be potentially actionable genomic alterations in patients with BTCs, especially perihilar cholangiocarcinoma and extrahepatic cholangiocarcinoma. The findings add to the growing data on genomic and immune landscapes of KRAS allelic variants in BTCs and are potentially of value to the planning of specific therapies for this heterogeneous patient group.

Immune Checkpoint Inhibitors for Advanced Biliary Tract Cancer

BTC is a rare and aggressive cancer disease bearing an overall dismal prognosis with only finite therapy options. Only combination chemotherapy regimens achieve disease control which is often only short-lived since the tumor tissue exhibits a high resistance to chemotherapy. The emergence of immune checkpoint inhibitors in recent years has significantly improved the survival of cancer patients and thus, has been integrated in the therapeutic management of several solid tumors, including melanoma, colorectal carcinoma (CRC), hepatocellular carcinoma (HCC), triple-negative breast cancer (TNBC), non-small-cell lung cancer (NSCLC). Investigation of the tumor biology of BTC and results of preliminary studies have shown that BTC may also be amenable to immunomodulation. In this review, we seek to give a comprehensive overview about the role, potential and clinical significance of ICPI in the management of BTC.

Molecular Targets and Emerging Therapies for Advanced Gallbladder Cancer

Biliary tract cancers (BTCs), for their low incidence, have been often considered together. Gallbladder cancer (GBC) is the most common biliary tract malignancy, characterized by late diagnosis and poor prognosis, and although it is considered a rare tumor in western countries, other areas of the world show considerable incidence rates. In 2010, results from the large phase III ABC-02 clinical trial on GBC identified the gemcitabine and cisplatin combination as the most effective first-line regimen for both GBC and other BTCs. Since then, various systemic therapies have proven active in BTCs in both first- and second-line settings. Molecular profiling has highlighted important genetic differences between GBC and other BTCs, opening new ways for targeted therapy in advanced disease where standard chemotherapies show marginal benefit. Genome-wide data analysis have shown that GBC molecular landscape offer possible strategies for precision medicine approaches, and a better molecular understanding of the GBC is needed to better stratify patients for treatment. In this review, we discuss the molecular targetable agents for GBC, including the results that emerged by clinical trials exploring new treatment strategies.

Development of Possible Next Line of Systemic Therapies for Gemcitabine-Resistant Biliary Tract Cancers: A Perspective from Clinical Trials

Biliary tract cancer (BTC) compromises a heterogenous group of tumors with poor prognoses. Curative surgery remains the first choice for localized disease; however, most BTC patients have had unresectable or metastatic disease. The gold standard therapy for these patients is chemotherapy with gemcitabine and cisplatin. There are no consensus guidelines for standard treatment in a second-line setting, although the data of the ABC-06 trial showed a slight survival benefit from oxaliplatin and 5-fluorouracil combination chemotherapy. Recent progress in comprehensive genomic profiling for advanced BTC (ABTC) has helped to clarify tumorigenesis and facilitate the coming era of precision medicine. Generally, targeted agents fail to show significant clinical benefits in unselected populations. Only fibroblast growth factor receptor 2 (FGFR2) fusion and isocitrate dehydrogenase (IDH)- and BRAF mutation-enriched populations have survival benefits from the corresponding inhibitors. Several interesting targeted agents for monotherapies or combination therapies with other compounds are currently ongoing or recruiting. Here, we review the published data from clinical trials of second-line therapies after the failure of gemcitabine-based chemotherapy in ABTC. The results were stratified by different genetic alternations, as well as by chemotherapy, targeted therapy and immunotherapy.