Abstract 305P
Background
Gall bladder cancers (GBCs) are highly aggressive tumors often diagnosed at an advanced stage with poor prognosis, and post-treatment outcomes with systemic chemotherapy are dismal. Understanding the molecular characterisation of GBCs may help alter the dismal outcomes with targeted therapeutics. 15-20% of GBCs have HER2/neu amplification or protein overexpression and have worse survival when compared to HER2/neu-negative disease. Data in regards to the efficacy of HER2/neu-targeted therapy in gall bladder cancers are sparse.
Methods
This was an observational study in treatmentnaive metastatic GBC's with HER2/neu positivity (defined by IHC 3+ or IHC 2+ and FISH amplified). Patients were given gemcitabine (1000 mg/m2 IV) + cisplatin (25mg/m2) on day 1 and day 8 X q 3 weeks with trastuzumab. Trastuzumab was given at a initial loading dose of 8mg/kg followed by 6mg/kg x q 3weeks until disease progression or unacceptable toxicity.
Results
From May 2022 to January 2023, 58 patients were screened for HER2/neu status. Amongst them 14 (24.13%) were found to have HER2-positive status. HER2/neu was detected by IHC in 6 (43%) and by FISH in 8 (57%) patients. These 14 patients received chemotherapy with trastuzumab. At a median follow up of 13.33 months, median PFS and OS was 7.24 months (95% CI: 5.67-8.80) and 8.90 months (95% CI: 7.03-9.86), respectively. Partial response was observed in 8 (57%) patients, 2 (14%) patients had stable disease, resulting in a disease control rate of 71%. Common grade 3 or 4 chemotherapy-related adverse events included, neutropenia (14%), thrombocytopenia (8%) and anemia (7%).
Conclusions
Addition of anti-HER2-directed therapy can better the dismal prognosis of HER2-positive metastatic carcinoma of gall bladder. This study has demonstrated achievement of OS and PFS on a par with HER2-negative subgroup with the addition of trastuzumab. HER2/neu-directed therapy is a promising avenue for appropriate patients of carcinoma gall bladder and should be explored further in randomised control trials.
Legal entity responsible for the study
R. Chhabra.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.