What is the role of immunotherapy in the treatment of locally advanced, unresectable gallbladder cancer?

Role of Immunotherapy in Locally Advanced Gallbladder Cancer

For locally advanced, unresectable gallbladder cancer, immunotherapy combined with chemotherapy is now the standard first-line treatment, specifically durvalumab plus gemcitabine-cisplatin, which has demonstrated superior outcomes and is FDA-approved for this indication 1.

First-Line Treatment Approach

The treatment landscape for locally advanced gallbladder cancer has fundamentally shifted with the integration of immunotherapy:

• Preferred regimen: Durvalumab (PD-L1 inhibitor) combined with gemcitabine and cisplatin is the recommended first-line systemic therapy 1
• This combination is FDA-approved and represents a Category 1 recommendation in NCCN guidelines 1
• The TOPAZ-1 trial established this as standard of care, showing meaningful improvements in survival outcomes 2, 3
• Alternative option: Pembrolizumab (PD-1 inhibitor) combined with gemcitabine and cisplatin is also approved based on the KEYNOTE-966 trial 2

Biomarker-Directed Immunotherapy

Beyond first-line treatment, specific molecular features can guide immunotherapy selection:

High Priority Testing

All patients with locally advanced gallbladder cancer should undergo molecular profiling for:

• MSI-H/dMMR status (microsatellite instability-high/mismatch repair deficiency) 1
• TMB-H status (tumor mutational burden-high) 1
• Testing should occur before or during first-line therapy 4

MSI-H/dMMR Tumors

• Anti-PD-1 monotherapy (pembrolizumab or nivolumab) is highly effective 1, 4
• This applies to patients who have not received prior checkpoint inhibitor therapy
• Response rates are substantially higher than in unselected populations

TMB-H Tumors

• Nivolumab plus ipilimumab combination shows meaningful activity 1
• For tissue TMB-high tumors: ORR 38.6%, median OS 15.0 months, median PFS 5.7 months
• Recommended as Category 2B for first-line or subsequent-line therapy in TMB-H disease
• Treatment-related adverse events occur in approximately 29-37% of patients

Subsequent-Line Immunotherapy

For patients with disease progression after first-line therapy who have not received prior checkpoint inhibitors:

• Nivolumab monotherapy is a Category 2B option 1
• In unselected biliary tract cancer patients: ORR 22% (investigator-assessed) or 11% (independent review), median OS 14.2 months
• Consider for patients with no satisfactory alternative treatment options
• Nivolumab subcutaneous formulation (with hyaluronidase) may substitute for IV administration

Conversion Therapy Strategy

A critical and emerging role for immunotherapy is enabling conversion from unresectable to resectable disease:

• Multiple case reports demonstrate successful R0 resections after immunochemotherapy 5, 6, 7, 8
• Typical approach: 8-9 cycles of chemotherapy plus immunotherapy (durvalumab or pembrolizumab) followed by surgical reassessment 6, 7
• Near-complete or complete pathological responses have been documented 6, 8
• This represents a paradigm shift from purely palliative to potentially curative intent

Practical algorithm for conversion therapy:

1. Initiate durvalumab + gemcitabine-cisplatin for locally advanced unresectable disease
2. Restage with cross-sectional imaging after 4-6 cycles
3. If substantial tumor regression occurs (partial response or better), obtain multidisciplinary surgical evaluation
4. Consider diagnostic laparoscopy to exclude peritoneal disease before proceeding with resection 6
5. If R0 resection achieved, continue adjuvant immunochemotherapy to complete planned cycles

Important Caveats

PD-L1 testing is NOT recommended for treatment selection in gallbladder cancer 1. While PD-L1 positive tumors show higher response rates, PD-L1 negative disease can still respond to immunotherapy, and the overall response rates are too low to justify exclusion based on PD-L1 status alone.

Avoid checkpoint inhibitors in patients who:

• Have already received prior checkpoint inhibitor therapy (limited benefit from re-challenge)
• Have active autoimmune disease requiring systemic immunosuppression
• Have severe baseline immune-related conditions

For patients with compromised performance status who cannot tolerate platinum-based regimens, gemcitabine monotherapy is preferred over immunotherapy combinations 4.

The integration of immunotherapy has transformed locally advanced gallbladder cancer from a uniformly fatal diagnosis to one where meaningful disease control, quality of life improvement, and even potential cure through conversion surgery are achievable goals 2, 6.