Calithera Biosciences Inc. shares surged 15% in premarket trade Wednesday, after the company said it has won fast track designation from the U.S. Food and Drug Administration for a treatment for renal cell carcinoma, or kidney cancer. The South San Francisco, Calif.based biotech said the designation was granted to its CB-839 glutaminase inhibitor in combination with cabozantinib for the treatment of patients with kidney cancer who have received one or two prior lines of therapy, including at least one vascular endothelial growth factor tyrosine kinase inhibitor or the combination of nivolumab and ipilimumab. The treatment is being evaluated in a trial involving 298 patients, with a primary endpoint of progression free survival. The FDA's fast track designation is given to help accelerate the development of drugs aimed at treating life-threatening diseases for which there is no treatment. Calithera shares are down 42% in the last 12 months, while the S&P 500 has gained 16%.