Can pembrolizumab be given to a patient with BRAF-negative anaplastic thyroid carcinoma?

Pembrolizumab for BRAF-Negative Anaplastic Thyroid Carcinoma

Yes, pembrolizumab can and should be given to patients with BRAF-negative anaplastic thyroid carcinoma (ATC), preferably in combination with lenvatinib as first-line therapy for metastatic disease. 1

Treatment Algorithm for BRAF-Negative ATC

First-Line Systemic Therapy Options

For patients with metastatic BRAF-negative ATC, the preferred approach is:

Pembrolizumab + Lenvatinib combination 1, 2

• This represents the most effective systemic option based on current guidelines
• NCCN 2025 guidelines specifically recommend immunotherapy (PD-1 inhibitors including pembrolizumab and nivolumab) regardless of tumor mutational burden (TMB) or combined positive score (CPS) 1
• Real-world data demonstrates 36% confirmed overall response rate with median overall survival of 7.7 months and progression-free survival of 6.2 months 3
• Complete responses achieved in 9% of patients, with median duration of response of 16 months 3

Alternative First-Line Options

If pembrolizumab/lenvatinib is not available or tolerated:

Chemotherapy regimens 2:

• Paclitaxel (175 mg/m²) + carboplatin (AUC 5) every 3 weeks
• Doxorubicin (60 mg/m²) + cisplatin (120 mg/m²) every 4 weeks
• Docetaxel (60 mg/m²) + doxorubicin (60 mg/m²) every 3 weeks

Single-agent pembrolizumab is also an option, though less effective than combination therapy 1

Key Evidence Supporting Pembrolizumab Use

PD-L1 Expression Matters

• 96% of BRAF-negative ATC patients have PD-L1 CPS ≥1 3
• Higher PD-L1 expression (≥50%) correlates with better outcomes 4
• Patients with PD-L1 TPS ≥50% showed particularly favorable responses 1

Clinical Efficacy Data

The combination of pembrolizumab + lenvatinib in BRAF wild-type ATC shows:

• 75% objective response rate in both first and second-line settings 4
• Three complete responses documented in recent case series 4
• Durable responses exceeding 12 months in multiple patients 4, 5

Practical Implementation

Dosing

• Pembrolizumab: 200 mg IV every 3 weeks OR 400 mg IV every 6 weeks 3
• Lenvatinib: Median starting dose 16 mg daily (range 10-20 mg based on tolerability) 3
• Start both agents within days of each other (median 0.5 days between initiation) 3

Treatment Duration

• Continue until unacceptable toxicity or disease progression
• Responses can be durable, with some patients maintaining control beyond 30 months 5

Critical Safety Considerations

Common Toxicities Requiring Monitoring

Immune-related adverse events (14% discontinuation rate) 3:

• Pneumonitis (most concerning - associated with poor prognosis) 6
• Colitis (led to pembrolizumab discontinuation in 3 patients) 3

Lenvatinib-specific risks:

• Fistula formation (tracheoesophageal or tracheocutaneous) - occurred in 2/36 patients 3, 7
• This is particularly concerning in patients with locoregional invasion of trachea/esophagus
• Monitor closely but note that some suspected fistulas required no intervention 3

When to Use Caution

• Patients with extensive locoregional invasion (46% of treated patients had radiological suspicion of tracheal/esophageal invasion) 3
• Active autoimmune disease (relative contraindication per FDA label) 8
• Severe hepatic impairment (unknown pharmacokinetics) 8

Neoadjuvant Setting

For locally advanced (stage IVB) BRAF-negative ATC:

• Administer pembrolizumab + lenvatinib for 4-6 weeks before re-staging 7
• If FDG-PET/CT shows tumor regression, proceed to surgical resection 7
• 8/12 patients showed tumor regression with neoadjuvant approach 7
• Continue systemic therapy in adjuvant setting post-surgery 7

Combination with Chemotherapy

Pembrolizumab + chemotherapy (carboplatin/paclitaxel) is an alternative strategy 9, 5:

• Particularly useful when rapid tumor reduction is required
• One case achieved sustained near-complete response lasting >30 months 5
• Consider when pembrolizumab/lenvatinib unavailable or when aggressive cytoreduction needed

Second-Line Options

If progression occurs on pembrolizumab + lenvatinib:

• Clinical trial enrollment (preferred) 2
• Alternative chemotherapy regimens 2
• Single-agent spartalizumab showed 19% ORR but is not superior to standard options 1

Bottom Line

The evidence strongly supports pembrolizumab use in BRAF-negative ATC, with the combination of pembrolizumab + lenvatinib representing the most effective systemic therapy option. This is endorsed by NCCN 2025 guidelines 1 and supported by robust real-world data 3, 4. The key is early initiation, close monitoring for immune-related toxicities (especially pneumonitis), and awareness of fistula risk in patients with locoregional invasion.