Lung cancer treated with targeted therapy: rare blood vessel inflammation as a side effect

What happened, in summary

A never-smoking woman in her early 70s with treated rheumatoid arthritis developed a persistent cough. CT and biopsy showed lung adenocarcinoma with a BRAF V600E mutation. The disease involved the pleura and was classified as Stage IV, cT4N3M1a.

She began targeted treatment with dabrafenib and trametinib. The doses had to be reduced because she developed a low white-blood-cell count and a skin rash. Despite these side effects, the lung cancer responded very well, and imaging showed a complete response.

About 6 months after targeted treatment began, follow-up CT showed new thickening and inflammation around the thoracic aorta. She did not have the usual symptoms of giant-cell arteritis, but the imaging pattern and blood-test changes supported large-vessel vasculitis. The timing raised concern that the inflammation had been triggered by the BRAF and MEK inhibitors.

Prednisolone and methotrexate were started to control the vasculitis. After the risks were discussed with her respiratory and rheumatology teams, she wished to continue dabrafenib and trametinib. The drugs were therefore continued at reduced doses with close monitoring while the vasculitis was treated. Three months later, the aortic inflammation had clearly improved. By 6 months, the steroid dose had been tapered, the vasculitis had not returned, and the lung cancer continued to show a maintained partial response. She remained on targeted treatment with both conditions under control.

Regular CT follow-up monitored both the aorta and the lung tumors while she stayed on reduced-dose targeted therapy. This allowed the treatment-related inflammation and cancer response to be assessed together. No vasculitis recurrence was seen during the steroid taper.