Genentech Warns Against Use of Avastin in Combination With Pfizer’s Sutent

Genentech is recommending that its cancer agent Avastin not be used in combination with Pfizer’s kinase inhibitor Sutent after several cases of microangiopathic hemolytic anemia (MAHA) were observed during an investigator-sponsored study.

The FDA recently issued a MedWatch report to oncologists regarding the potential safety problem, and Genentech issued a “dear healthcare professional” letter alerting physicians.

The trial was a Phase I dose-escalation study testing the drugs against renal cell carcinoma. It included 25 patients who were given a fixed dose of Avastin (bevacizumab) and escalating doses of Sutent (sunitinib malate). Of the 12 patients who received the highest Sutent doses, five had laboratory findings consistent with MAHA, according to Genentech.

“Two of these cases were considered severe with evidence of thrombocytopenia, anemia, reticulocytosis, reductions in serum haptoglobin, schistocytes on peripheral smear, modest increases in serum creatinine levels, and severe hypertension, reversible posterior leukoencephalopathy syndrome (RPLS) and proteinuria,” Genentech says in the letter.

“The findings in these two cases were reversible within three weeks upon discontinuation of both drugs without additional intervention,” the company adds.