Fibrolamellar carcinoma (FLC) is a rare, lethal, early-onset liver cancer with a critical need for new therapeutics. The primary driver in FLC is the fusion oncoprotein, DNAJ-PKAc, which remains challenging to target therapeutically. It is critical, therefore, to expand understanding of the FLC molecular landscape to identify druggable pathways/targets. Here, we perform the most comprehensive integrative proteo-metabolomic analysis of FLC. We also conduct nutrient manipulation, respirometry analyses, as well as key loss-of-function assays in FLC tumor tissue slices from patients. We propose a model of cellular energetics in FLC pointing to proline anabolism being mediated by ornithine aminotransferase hyperactivity and ornithine transcarbamylase hypoactivity with serine and glutamine catabolism fueling the process. We highlight FLC\'s potential dependency on voltage-dependent anion channel (VDAC), a mitochondrial gatekeeper for anions including pyruvate. The metabolic rewiring in FLC that we propose in our model, with an emphasis on mitochondria, can be exploited for therapeutic vulnerabilities.

UNASSIGNED: Fibrolamellar carcinoma (FLC) is a rare, difficult-to-treat liver cancer primarily affecting pediatric and adolescent patients, and for which precision medicine approaches have historically not been possible. The DNAJB1-PRKACA gene fusion was identified as a driver of FLC pathogenesis. We aimed to assess whether FLC tumors maintain dependency on this gene fusion and determine if PRKACA is a viable therapeutic target.
UNASSIGNED: FLC patient-derived xenograft (PDX) shRNA cell lines were implanted subcutaneously into female NOD-SCID mice and tumors were allowed to develop prior to randomization to doxycycline (to induce knockdown) or control groups. Tumor development was assessed every 2 days. To assess the effect of treatment with novel selective PRKACA small molecule kinase inhibitors, BLU0588 and BLU2864, FLC PDX tumor cells were implanted subcutaneously into NOD-SCID mice and tumors allowed to develop. Mice were randomized to treatment (BLU0588 and BLU2864, orally, once daily) or control groups and tumor size determined as previously.
UNASSIGNED: Knockdown of DNAJB1-PRKACA reversed a FLC-specific gene signature and reduced PDX tumor growth in mice compared to the control group. Furthermore, FLC PDX tumor growth was significantly reduced with BLU0588 and BLU2864 treatment vs control (P = .003 and P = .0005, respectively).
UNASSIGNED: We demonstrated, using an inducible knockdown and small molecule approaches, that FLC PDX tumors were dependent upon DNAJB1-PRKACA fusion activity. In addition, this study serves as a proof-of-concept that PRKACA is a viable therapeutic target for FLC and warrants further investigation.

An 11-year-old boy presented with vomiting and abdominal pain. Ultrasonography and blood tests revealed no abnormalities. He was diagnosed with viral gastroenteritis; however, the following morning, he was found dead in bed. Postmortem examination revealed that a 1,900 mL hemorrhage with strong coagulation from the diaphragm was the cause of death. He had no traumatic episodes, injuries, or a medical history of hemorrhagic diathesis. The presence of a fibrin-like clot indicated coagulation activation; however, most criteria for disseminated intravascular coagulation were not observed. Fibrolamellar carcinoma, a rare hepatocellular carcinoma, was found; however, liver disorder was not estimated based on the pathological findings. In conclusion, the mechanism of hemorrhage could not be explained. Although we were unable to identify the cause of the hemorrhage, we could not completely rule out the possibility that fibrolamellar carcinoma had an unknown influence on the hemorrhage. Given the limited number of studies on fibrolamellar carcinoma, we present a case of a boy with undiagnosed fibrolamellar carcinoma who died due to severe hemorrhage.

Fibrolamellar carcinoma is a rare liver tumor, with most cases arising in people younger than 40 years of age. We present a case series of five patients with histological confirmation of fibrolamellar carcinoma who had liver resection as the primary treatment. The median age of diagnosis was 24 years with nonspecific clinical manifestations in otherwise healthy patients. Alpha-fetoprotein levels were widely variable. Patients had classical imaging, macroscopic, and microscopic findings. Most of our patients underwent a hemihepatectomy and 60% recurred after the first year.

Fibrolamellar carcinoma (FLC) is a liver tumor with a high mortality burden and few treatment options. A promising therapeutic vulnerability in FLC is its driver mutation, a conserved DNAJB1-PRKACA gene fusion that could be an ideal target neoantigen for immunotherapy. In this study, we aim to define endogenous CD8 T cell responses to this fusion in FLC patients and evaluate fusion-specific T cell receptors (TCRs) for use in cellular immunotherapies. We observe that fusion-specific CD8 T cells are rare and that FLC patient TCR repertoires lack large clusters of related TCR sequences characteristic of potent antigen-specific responses, potentially explaining why endogenous immune responses are insufficient to clear FLC tumors. Nevertheless, we define two functional fusion-specific TCRs, one of which has strong anti-tumor activity in vivo. Together, our results provide insights into the fragmented nature of neoantigen-specific repertoires in humans and indicate routes for clinical development of successful immunotherapies for FLC.

UNASSIGNED: Fibrolamellar hepatocellular carcinoma (FLHCC) is a rare primary liver malignancy often diagnosed at advanced stages. While there are limited data on the efficacy of specific agents, we aim to report outcomes of patients treated with systemic therapies and explore prognostic factors.
UNASSIGNED: Medical records of patients treated between 2010 and 2022 were reviewed. Treatments were defined after multidisciplinary assessment. Descriptive statistics were used for baseline demographics. Time-to-event outcomes were estimated using the Kaplan-Meier method, compared by log-rank and adjusted by a regression model. Radiomic features (including size, shape, and texture) of the primary lesion were extracted and dimensionality reduced. An unsupervised Gaussian Mixture Model (GMM) clustering was performed, and survival was compared between clusters.
UNASSIGNED: We identified 23 patients: 12 males, with a median age of 23.6 years. At diagnosis, 82.6% had metastases, most frequently to the lungs (39.1%), lymph nodes (39.1%), and peritoneum (21.7%). Patients received a median of three lines (1-8) of treatment, including different regimens. Sorafenib (39.1%), capecitabine (30.4%), and capecitabine/interferon (13%) were the most used first-line regimens. The median time-to-failure was 3.8 months (95% CI: 3.2-8.7). Capecitabine + interferon (42.1%) and platinum combinations (39.1%) were the most used second-line regimens, with a time-to-failure of 3.5 months (95% CI: 1.5-11.6). Median overall survival was 26.7 months (95% CI: 15.1-40.4). A high baseline neutrophil-to-lymphocyte ratio (NLR) was associated with worse survival (p=0.02). Radiomic features identified three clusters, with one cluster (n=6) having better survival (40.4 vs 22.6 months, p=0.039). Tumor sphericity in the arterial phase was the most relevant characteristic associated with a better prognosis (accuracy=0.93).
UNASSIGNED: FLHCC has unique features compared to conventional HCC, including young onset, gender balance, and absence of hepatopathy. Systemic therapies can provide encouraging survival, but lack of uniformity precludes defining a preferable regimen. Radiomics and NLR were suggested to correlate with prognosis and warrant further validation.

The alternative lengthening of telomeres (ALT) phenotype is characterized by ultra-bright telomeres on fluorescence in situ hybridization (FISH) and is a marker of a unique mechanism of telomere maintenance in tumors. ALT does not occur in normal tissues. ALT has been described in hepatocellular carcinoma (5-10%) and in primary hepatic angiosarcomas (75%). To study the frequency of ALT in other primary hepatic tumors, a wide range of primary hepatic neoplasms were retrieved. The tumors included the following: intrahepatic and hilar cholangiocarcinomas (N = 110), hepatic adenomas (N = 35), hepatocellular carcinomas (N = 30), fibrolamellar carcinomas (n = 11), combined cholangiocarcinoma-hepatocellular carcinomas (N = 8), carcinosarcoma (N = 10), hepatoblastomas (N = 5), hemangiomas (N = 4), angiosarcomas (N = 8), epithelioid hemangioendotheliomas (N = 10), calcified nested stromal epithelial tumor (N = 2), embryonal sarcoma (N = 2), rhabdoid tumor (N = 1), bile duct adenoma (N = 1), and angiomyolipoma (N = 1). For epithelial tumors, ALT-FISH was positive in one carcinosarcoma (10% of cases), one cholangiocarcinoma (1% of cases), and one combined hepatocellular carcinoma-cholangiocarcinoma (13% of cases). In the hepatocellular carcinoma component of both the carcinosarcoma and the combined hepatocellular carcinoma-cholangiocarcinoma, the tumor cells showed patchy marked nuclear pleomorphism akin to that described previously for chromophobe hepatocellular carcinoma, which are typically ALT FISH positive. The ALT-positive cholangiocarcinoma also showed patchy, striking nuclear pleomorphism. For soft tissue tumors, ALT was positive in two angiosarcomas (N = 2; 25% of cases). In summary, this study shows that ALT-FISH is positive in rare carcinosarcomas, cholangiocarcinomas, and combined cholangiocarcinoma-hepatocellular carcinoma. ALT is not a significant mechanism of telomere maintenance in hepatocellular adenomas or fibrolamellar carcinomas and was negative in all other tested primary hepatic neoplasms. ALT-FISH is also positive in a subset of primary hepatic angiosarcomas.

Fibrolamellar carcinoma (FLC) is a rare primary liver tumor affecting predominantly younger and otherwise healthy patients. Typically, FLC presents with advanced disease due to the paucity of typical symptoms and no history of underlying liver disease. Depending on tumor characteristics and the patient\'s general condition, surgical treatment is the most promising treatment modality. Aggressive resection and liver transplantation have been utilized and are presently indispensable curative treatment options. Under certain circumstances surgical resection is also possible for metachronous metastases or local recurrence. Recent tumor biology discoveries have contributed to improved diagnostic specificity and systemic treatment options.

Fibrolamellar carcinoma (FLC) is a rare variant of hepatocellular carcinoma (HCC), comprising 1%-9% of all HCCs. FLC is a poorly understood malignancy, which seems to be more prevalent in young patients with no underlying liver diseases. The term \"fibrolamellar\" is derived from thick fibrous collagen bands surrounding the tumor cells. Unlike HCC, cirrhosis and viral hepatitis infection are not predisposing to FLC, and it is not associated with elevations in serum alpha-fetoprotein. FLC patients often present with vague abdominal pain, nausea, malaise, and weight loss. Most cases present are at an advanced stage at the time of initial diagnosis. However, curative treatment options can still be offered to up to 70% of patients. Surgery (resection/liver transplantation) is the mainstay of treatment and the only potentially curative option. FLCs have been less chemo-responsive than the conventional HCC, however, in advanced cases, multimodality treatments can be effective. Recent advances in molecular studies of FLC have found a unique DNAJB1-PRKACA fusion transcript in most of the cases studied. The review aims to describe clinical characteristics, diagnostic methods, and therapeutic modalities for this rare tumor to raise awareness among clinicians and surgeons.

BACKGROUND: Fibrolamellar carcinoma (FLC) is a rare liver cancer that predominantly affects younger patients without a history of liver disease. Surgical resection is the cornerstone of therapy and represents the best potentially curative treatment option. Modest objective responses with cytotoxic chemotherapy alone or combined with immune checkpoint inhibitors (ICIs) have been reported; however, there are no established systemic therapy regimens for unresectable or metastatic FLC.
METHODS: We report a case of a 23-year-old woman with FLC who presented with a 11.5 × 8.3 cm left liver mass and subsequently underwent resection as initial therapy. Molecular analysis of her surgical tissue revealed a DNAJB1-PRKACA fusion gene. The patient developed biopsy-proven recurrent FLC with multiple liver lesions but without any distant metastatic disease only 3 months after initial resection. In light of emerging data, the patient was treated with a novel triple therapy regimen including 5-fluorouracil (5-FU), interferon (IFN) alfa-2b, and nivolumab. Partial radiographic response was achieved after 4 treatments and complete response was achieved after 12 cycles with the combination. The patient received 2 more doses of 5-FU/IFN alfa-2b without nivolumab and underwent orthotopic liver transplantation (OLT) 6 months after the last dose of ICI. Pathological examination of the explanted liver remarkably confirmed pathologic complete response. She remains recurrence-free and is on active surveillance.
CONCLUSIONS: For patients with unresectable/recurrent FLC with no distant disease, the combination of 5-FU, IFN alfa-2b, and nivolumab could be an effective systemic therapy option. The use of this chemoimmunotherapy regimen to downstage FLC prior to OLT may be worth investigating further.