Sarcomatoid renal cell carcinoma (sRCC) is a rare and aggressive form of RCC in which the cells in the tumours look like the cells of a sarcoma (cancer of connective tissue such as muscles, nerves, fat, blood vessels etc.). Patients with metastatic RCC with sarcomatoid features are difficult to treat and do not respond well to anti-angiogenic targeted therapy, such as sunitinib and pazopanib. This real world study looked at 66 patients with sarcomatoid RCC who were treated with cabozantinib as a second-line or third-line treatment.
Most patients had been treated with sunitinib or pazopanib as their first-line treatment and the majority of patients had intermediate or poor risk disease. Patients were followed for an average of 24 months. Partial responses were seen in 15 patients (44%) and stable disease in 10 patients (29%) when cabozantinib was given as a second-line treatment. When cabozantinib was given as a third-line treatment, 15 patients (47%) had partial responses and 11 patients had stable diseases (34%). Nearly half of all patients (47%) responded to treatment with a reduction in the size of their cancer.
The average time to when the drugs stopped working and the cancer started growing again (progression-free survival) was 7.59 months, while the average survival time was 9.11 months. Female patients, patient with bone metastases and patients in poor health faired poorly.
In conclusion, cabozantinib shows promise for the treatment of sarcomatoid RCC, although there was improved benefit in males and in patients without bone metastases, which differs from previous studies with cabozantinib. These findings need further investigation.