Erdafitinib Yields 55% Response Rate in FGFR-Altered Advanced Cholangiocarcinoma: Insights from a Pooled Phase 2 Analysis

Introduction: The Targeted Therapy Landscape in Cholangiocarcinoma

Cholangiocarcinoma (CCA), a group of rare but aggressive malignancies arising from the biliary tree, has historically been associated with a poor prognosis and limited therapeutic options beyond first-line gemcitabine-based chemotherapy. However, the advent of precision medicine has shifted the paradigm, particularly for intrahepatic cholangiocarcinoma (iCCA), where approximately 40% of patients harbor actionable genetic alterations. Among the most significant of these are fibroblast growth factor receptor 2 (FGFR2) fusions or rearrangements, which occur in nearly 10-20% of patients with iCCA.

Erdafitinib, a potent oral pan-FGFR tyrosine kinase inhibitor, was initially approved for the treatment of locally advanced or metastatic urothelial carcinoma with susceptible FGFR3 or FGFR2 alterations. Given its broad activity across multiple FGFR isoforms, its efficacy in other FGFR-driven malignancies, specifically CCA, has been a subject of intense investigation. This article explores the findings of a recently published pooled analysis of the RAGNAR and LUC2001 studies, which evaluated erdafitinib in patients with advanced or metastatic CCA harboring FGFR alterations.

Study Design and Patient Population

The pooled analysis integrated data from two distinct phase 2 trials: RAGNAR and LUC2001. RAGNAR was a global, open-label, tumor-agnostic study investigating erdafitinib in patients with advanced solid tumors harboring FGFR alterations who had progressed on at least one prior line of systemic therapy. LUC2001 was an open-label, multicenter phase 2a study specifically focused on Asian patients with advanced solid tumors.

Inclusion Criteria and Treatment Protocol

In total, 78 patients with cholangiocarcinoma were pooled for efficacy and safety analyses (66 from RAGNAR and 12 from LUC2001). All patients had documented FGFR alterations (including fusions, mutations, and amplifications) and had received at least one prior line of therapy. The treatment regimen consisted of oral erdafitinib at a starting dose of 8 mg once daily. Notably, the protocol allowed for pharmacodynamically guided up-titration to 9 mg daily for patients who did not reach target serum phosphate levels and experienced no significant adverse events within the first cycle.

Primary and Secondary Endpoints

The primary efficacy endpoint was the objective response rate (ORR) as assessed by a blinded independent review committee (BIRC). Secondary endpoints included the duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety/tolerability profiles.

Key Findings: Robust Clinical Efficacy

The results of the pooled analysis, published in Clinical Cancer Research, underscore the significant clinical activity of erdafitinib in this patient population. At a median follow-up of 14.7 months, the efficacy data revealed several noteworthy outcomes.

Objective Response and Survival Metrics

The ORR was reported at 55% (95% CI: 43.4–66.4), which is remarkably high for a pretreated population with advanced CCA. The median time to response was rapid, at 1.7 months, suggesting that patients who respond to erdafitinib tend to do so early in the course of treatment.

Survival outcomes were equally encouraging:

• Median Duration of Response (DOR): 6.9 months (95% CI: 4.37–8.61)
• Median Progression-Free Survival (PFS): 8.5 months (95% CI: 6.83–9.72)
• Median Overall Survival (OS): 18.1 months (95% CI: 13.40–24.28)

These results are particularly impressive when compared to historical benchmarks for second-line chemotherapy in CCA, where ORRs typically range from 5% to 10% and median OS rarely exceeds 6 to 9 months.

Safety and Tolerability Profile

The safety profile of erdafitinib in patients with CCA was consistent with the known class effects of FGFR inhibitors. Most treatment-emergent adverse events (TEAEs) were manageable through dose modifications or supportive care.

Common Adverse Events

The most frequently reported TEAEs included:

• Hyperphosphatemia: 83% (a pharmacodynamic effect related to FGFR1 inhibition in the kidneys)
• Stomatitis: 72%
• Diarrhea: 68%
• Dry mouth: 51%
• Palmar-plantar erythrodysesthesia (PPE): 51%

Serious Adverse Events and Discontinuation

Serious TEAEs were reported in 42% of patients. Importantly, while dose interruptions and reductions were common, only 12% of patients discontinued treatment due to TEAEs. This suggests that with proactive monitoring and management—particularly for dermatologic and gastrointestinal toxicities—long-term treatment with erdafitinib is feasible for the majority of patients.

Expert Commentary: Placing Erdafitinib in the Context of Current Care

The efficacy of erdafitinib in this pooled analysis aligns with results seen from other FGFR-targeted agents, such as pemigatinib and futibatinib, which have already received regulatory approvals for FGFR2-fused CCA. However, the ORR of 55% observed with erdafitinib is among the highest reported in this class of drugs for this indication.

Mechanistic Insights

One of the critical considerations in treating FGFR-altered CCA is the development of resistance. Secondary mutations in the FGFR kinase domain (such as the N549H gatekeeper mutation) frequently emerge following treatment with first-generation ATP-competitive inhibitors. While erdafitinib is also an ATP-competitive inhibitor, its high potency and specific binding profile may contribute to the robust responses observed. The inclusion of patients with various types of FGFR alterations (not just fusions) in this analysis also broadens the potential clinical utility of the drug.

Clinical Implications

For clinicians, these findings reinforce the necessity of early comprehensive genomic profiling (CGP) for all patients with advanced cholangiocarcinoma. Identifying FGFR fusions or mutations early in the disease course allows for better sequencing of therapies. Given the 18.1-month median OS, erdafitinib represents a potent option for maintaining disease control and extending life in a population that previously had few effective choices.

Conclusion

The pooled analysis of the RAGNAR and LUC2001 studies confirms that erdafitinib is a highly effective and relatively well-tolerated therapy for patients with FGFR-altered advanced or metastatic cholangiocarcinoma. With an ORR of 55% and a median OS exceeding 18 months, erdafitinib solidifies the role of FGFR inhibition as a cornerstone of precision oncology in biliary tract cancers. Future research will likely focus on combination strategies to overcome resistance and move these targeted therapies into the first-line setting.

References

1. Pant S, Park JO, Su WC, et al. Erdafitinib in Patients with FGFR-altered Advanced or Metastatic Cholangiocarcinoma. Clin Cancer Res. 2025 Dec 29. doi: 10.1158/1078-0432.CCR-25-2264.
2. Abou-Alfa GK, Sahai V, Hollebecque A, et al. Pemigatinib for previously treated, locally advanced or metastatic cholangiocarcinoma: a multicentre, open-label, phase 2 study (FIGHT-202). Lancet Oncol. 2020;21(5):671-684.
3. Goyal L, Meric-Bernstam F, Hollebecque A, et al. Futibatinib in FGFr2-Rearranged Intrahepatic Cholangiocarcinoma. N Engl J Med. 2023;388(3):228-239.