ASLAN001 in Patients With Advanced or Metastatic Cholangiocarcinoma Who Progressed on at Least 1 Line of Systemic Therapy

Cholangiocarcinoma (CCA) is a malignancy arising from the biliary epithelium characterized by poor prognosis and poor response to current treatments. Emerging at any portion of the biliary tree, it includes a group of tumours with epidemiologic, morphologic, biologic, and clinical heterogeneity. Despite recent medical advances, the long-term outcomes and recurrence rates for CCA are poor. The 5-year survival rate following surgical resection is 11-40%. Tumour recurrence rates are as high as 50-65%, with a median time to recurrence between 12-43 months.

In the United States, the incidence and mortality of CCA have increased over the last 30 years without clear underlying etiological reasons. The only curative therapy is surgical; however this is not an option for many patients given the stage of the disease at presentation and metastasis. While improvements in diagnostic modalities and neoadjuvant chemotherapy have allowed for detection at earlier stages and greater survival rates, the prognosis is still unfavorable. Therapies that can decrease tumour growth, improve resection outcomes, increase survival rates, and decrease recurrence would make a great impact on the quality of life of CCA patients and are urgently needed.

Currently, the Food and Drug Administration (FDA)-approved agents used in unresectable CCA include gemcitabine, capecitabine, cisplatin, oxaliplatin, fluoropyrimidines (including 5-fluorouracil), or a combination of these. However, none are FDA-approved primarily for use in CCA specifically. Gemcitabine and cisplatin combination therapy, along with fluoropyrimidine-based or other gemcitabine-based regimens are part of the guidelines for unresectable cancer per the National Comprehensive Cancer Network. To date, the most effective chemotherapy regimen is administration of gemcitabine with cisplatin or oxaliplatin, which have now become the standard of care for systemic therapy. Even this most efficacious treatment has been found to only modestly increase overall survival (11.7 months vs 8.3 months for patients receiving gemcitabine alone) and progression-free survival (8.4 vs 6.5 months). Standard treatment as second-line chemotherapy for CCA is unclear as there is no significant evidence for specific therapy which indicates that further chemotherapy beyond progression on first-line chemotherapy improves survival.

CCA involves mutations in members of the ErbB family, including EGFR and HER2 mutations. EGFR is overexpressed in both intrahepatic and extrahepatic CCA (30.8% and 20.9%, respectively) and is an independent prognostic factor in intrahepatic cases, per Yang et al 2014. While this study found overexpression of HER2 exclusively in extrahepatic samples (and only in 4.5% of these), previous studies have implicated this protein in both extra- and intrahepatic tumours. Settakorn et al (2005) showed HER2 expression is correlated with high histological grade in intrahepatic CCA. Kim et al. (2007) found HER2 (gene and protein levels) are overexpressed in approximately 30% of extrahepatic CCA patients and is a prognostic factor for survival in those with lymph node metastasis.

EGFR, HER2, and HER4 are single-pass transmembrane glycoprotein receptors, members of the type I receptor tyrosine kinase family. Upon ligand binding, their activation induces the homo- or heterodimerization and subsequent phosphorylation of intracellular tyrosines, which lead to both cell proliferation and survival and therefore cancer development and progression. EGFR and HER2 inhibitors have both demonstrated clinical efficacy in cancer treatment. The simultaneous inhibition of both represents a new therapeutic approach for broadly targeting different tumour types that may be more effective than selective inhibition of each receptor.

Varlitinib, also known as ASLAN001 is a potent, orally active inhibitor of the receptor tyrosine kinases epidermal growth factor (EGFR) and human epidermal growth factor receptors 2 and 4 (HER2, HER4). In cell-based assays, varlitinib has been shown to potently inhibit the phosphorylation of EGFR, HER2, and HER4 in a dose-dependent manner. In cell lines overexpressing HER2, varlitinib also inhibited the phosphorylation of the HER2 downstream effector AKT.

ASLAN hypothesises that varlitinib will inhibit EGFR, HER2, HER4 as their mutations results in CCA, thus in turn inhibiting the growth of cancerous cells and development/progression. ASLAN believes that varlitinib is a compound that may be beneficial to patients with cancer by simultaneous inhibition of these receptors.