Understanding RET Fusion in Lung Cancer

RET (Rearranged During Transfection) fusion mutations occur in approximately 1-2% of non-small cell lung cancers (NSCLC). While relatively rare, RET+ patients have access to highly effective targeted therapies with RET inhibitors, particularly selpercatinib and pralsetinib, showing impressive clinical outcomes.

1-2%

of NSCLC patients

RET Fusion

Rare, highly actionable

2 FDA-approved

RET inhibitors

60%+ response

With RET-targeted therapy

RET Fusion Partners and Variants

RET fuses with several partner genes, with KIF5B-RET and CCDC6-RET being the most common. Each fusion variant has slightly different characteristics, but all respond to RET-selective inhibitors:

KIF5B-RET (~40%)

Most common RET fusion partner in lung cancer, responsive to both selpercatinib and pralsetinib.

CCDC6-RET (~20%)

Second most common, shows excellent response to RET-selective inhibitors.

Other Partners (~40%)

NCOA4-RET, TRIM24-RET, TRIM33-RET, and other rare fusion partners with good drug sensitivity.

Treatment Pathways for RET+ NSCLC

First-Line Therapy

Selpercatinib (Retevmo) - FDA approved for RET+ NSCLC
Pralsetinib (Gavreto) - Alternative RET inhibitor
Response rates 60%+ in clinical trials
Excellent side effect profile

Post-First-Line RET Inhibitor

Switching between selpercatinib and pralsetinib
Next-generation RET inhibitors in development
Chemotherapy + immunotherapy combinations
Trials targeting resistance mechanisms

CNS Activity & Brain Metastases

Selpercatinib and pralsetinib cross blood-brain barrier
Effective for untreated brain metastases
Often avoids need for separate CNS radiation
Leptomeningeal disease management

Resistance Management

Secondary RET mutations can emerge
Next-generation RET inhibitors for mutations
Combination approaches in development
Alternative signaling pathway inhibition

Frequently Asked Questions

How is RET fusion detected in lung cancer? +

RET fusions are best detected using next-generation sequencing (NGS) with RNA component or targeted fusion panel testing. Standard DNA-based NGS can miss some RET fusions, so RNA-based testing is recommended. FISH testing can also detect RET rearrangements in some cases. Make sure your testing includes comprehensive fusion detection to identify RET if present.

What is the difference between selpercatinib and pralsetinib? +

Both selpercatinib (Retevmo) and pralsetinib (Gavreto) are RET-selective inhibitors with similar effectiveness. Selpercatinib was the first to gain FDA approval for RET+ NSCLC and has extensive clinical data. Pralsetinib is an alternative option. Both have good CNS penetration and comparable response rates. Your oncologist will help choose based on individual factors and tolerance.

Can RET inhibitors treat brain metastases? +

Yes, both selpercatinib and pralsetinib have good blood-brain barrier penetration and can effectively treat brain metastases without separate CNS-directed therapy. This is a significant advantage for RET+ patients with asymptomatic brain metastases, allowing for systemic monotherapy. This has transformed treatment approach for RET+ patients with CNS involvement.

What is the prognosis for RET+ lung cancer patients? +

RET+ patients treated with selpercatinib or pralsetinib have favorable outcomes compared to historical chemotherapy results. Response rates exceed 60%, with median progression-free survival often exceeding 12-16 months. Early identification and treatment with appropriate RET inhibitors significantly improves prognosis compared to standard chemotherapy approaches.

RET Fusion Lung Cancer