Integrated Phosphoproteomics for Identifying Substrates of Human Protein Kinase A (PRKACA) and Its Oncogenic Mutant DNAJB1-PRKACA.

The DNAJB1-PRKACA fusion is the signature genetic event of fibrolamellar hepatocellular carcinoma (FL-HCC), a rare but lethal liver cancer that primarily affects adolescents and young adults. A deletion fuses the first exon of the HSP40 gene (DNAJB1), with exons 2-10 of protein kinase A (PRKACA), producing the chimeric kinase DNAJB1-PKAca (J-PKAca). The HSP40 portion's scaffolding/chaperone function has been implicated in redirecting substrate recognition to upregulate oncogenic pathways, but the direct substrates of this fusion are not fully known. We integrated cell-based and in vitro phosphoproteomics to identify substrates targeted directly by PKA and J-PKAca, comparing phosphoproteome profiles from cells with in vitro rephosphorylation of peptides and proteins from lysates using recombinant enzymes. We identified a subset of phosphorylation sites in both cell-based and in vitro experiments, as well as altered pathways and proteins consistent with observations from related studies. We also treated cells with PKA inhibitors that function by two different mechanisms (rpcAMPs and PKI) and examined phosphoproteome profiles, finding some substrates that persisted in the presence of inhibitors and revealing differences between WT and chimera. Overall, these results provide potential insights into J-PKAca's oncogenic activity in a complex cellular system and may provide candidate targets for therapeutic follow-up.

Clinical features and surgical outcomes of fibrolamellar hepatocellular carcinoma: retrospective analysis of a single-center experience.

BACKGROUND: Clinicopathological features and surgical outcomes of patients with fibrolamellar hepatocellular carcinoma (FL-HCC) are underreported. The aim of this study is to describe clinical characteristics and surgical outcomes for patients with this rare tumor to raise awareness among clinicians and surgeons. METHODS: Retrospective review of records of a tertiary referral center and specialized liver unit was performed. Out of 3623 patients who underwent liver resection, 366 patients received surgical treatment for HCC; of them, eight (2.2%) had FL-HCC and were resected between October 2001 and December 2018. RESULTS: Eight patients (3 males and 5 females) with FL-HCC (median age 26 years) underwent primary surgical treatment. All patients presented with unspecific symptoms or were diagnosed as incidental finding. No patient had cirrhosis or other underlying liver diseases. Coincidentally, three patients (37.5%) had a thromboembolic event prior to admission. The majority of patients had BCLC stage C and UICC stage IIIB/IVA; four patients (50%) presented with lymph node metastases. The median follow-up period was 33.5 months. The 1-year survival was 71.4%, and 3-year survival was 57.1%. Median survival was at 36.4 months. Five patients (62.5%) developed recurrent disease after a median disease-free survival of 9 months. Two patients (25.0%) received re-resection. CONCLUSION: FL-HCC is a rare differential diagnosis of liver masses in young patients. Since the prognosis is limited, patients with incidental liver tumors or lesions with suspicious features in an otherwise healthy liver should be presented at a specialized hepatobiliary unit. Thromboembolism might be an early paraneoplastic symptom and needs to be elucidated further in the context of FL-HCC.

FusionVAC22_01: a phase I clinical trial evaluating a DNAJB1-PRKACA fusion transcript-based peptide vaccine combined with immune checkpoint inhibition for fibrolamellar hepatocellular carcinoma and other tumor entities carrying the oncogenic driver fusion.

The DNAJB1-PRKACA fusion transcript was identified as the oncogenic driver of tumor pathogenesis in fibrolamellar hepatocellular carcinoma (FL-HCC), also known as fibrolamellar carcinoma (FLC), as well as in other tumor entities, thus representing a broad target for novel treatment in multiple cancer entities. FL-HCC is a rare primary liver tumor with a 5-year survival rate of only 45%, which typically affects young patients with no underlying primary liver disease. Surgical resection is the only curative treatment option if no metastases are present at diagnosis. There is no standard of care for systemic therapy. Peptide-based vaccines represent a low side-effect approach relying on specific immune recognition of tumor-associated human leucocyte antigen (HLA) presented peptides. The induction (priming) of tumor-specific T-cell responses against neoepitopes derived from gene fusion transcripts by peptide-vaccination combined with expansion of the immune response and optimization of immune function within the tumor microenvironment achieved by immune-checkpoint-inhibition (ICI) has the potential to improve response rates and durability of responses in malignant diseases. The phase I clinical trial FusionVAC22_01 will enroll patients with FL-HCC or other cancer entities carrying the DNAJB1-PRKACA fusion transcript that are locally advanced or metastatic. Two doses of the DNAJB1-PRKACA fusion-based neoepitope vaccine Fusion-VAC-XS15 will be applied subcutaneously (s.c.) with a 4-week interval in combination with the anti-programmed cell death-ligand 1 (PD-L1) antibody atezolizumab starting at day 15 after the first vaccination. Anti-PD-L1 will be applied every 4 weeks until end of the 54-week treatment phase or until disease progression or other reason for study termination. Thereafter, patients will enter a 6 months follow-up period. The clinical trial reported here was approved by the Ethics Committee II of the University of Heidelberg (Medical faculty of Mannheim) and the Paul-Ehrlich-Institute (P-00540). Clinical trial results will be published in peer-reviewed journals. Trial registration numbers: EU CT Number: 2022-502869-17-01 and ClinicalTrials.gov Registry (NCT05937295).

Case Report of Fibrolamellar Hepatocellular Carcinoma in A 15-Year-old Male.

Background: A rare form of hepatocellular cancer is called fibrolamellar hepatocellular carcinoma (FL-HCC) which occurs mostly in young adults who are medically free, regardless of their gender. It usually presents with abdominal pain with right upper quadrant palpable mass, nausea, and weight loss associated with higher Alpha-Fetoprotein (AFP) in some cases. Objective: We report a case of a 15-year-old male patient who was diagnosed with (FL-HCC), successfully treated with surgical resection and is currently free of relapses. Case presentation: A 15-year-old male patient with no previous medical or surgical history, presented with recurrent vomiting for two months, weight loss, and loss of appetite. Patient presented with normal systemic examination except for abdominal examination which revealed a generalized distended abdomen with mild tenderness in the right upper quadrant with the presence of hepatomegaly. Laboratory and radiological investigation showed high level of (AFP). CT and liver MRI showed large right hepatic lobe lesion then TRU-CUT needle biopsy was performed which showed Fibrolamellar hepatocellular carcinoma and patient underwent surgical resection with no postoperative complication followed by multiple cycle of chemotherapy and no signs of relapse with 3 year follow up. Conclusion: Fibrolamellar hepatocellular carcinoma is rear type hepatocellular carcinoma which occurs mostly in young adults who are medically free with vague symptom and to diagnose it need high index of suspicion and variers Laboratory and radiological investigation including biopsy. However, it can be treated successfully by surgical resection followed by chemotherapy in selected cases if diagnosis in timely manner.