Francois Lebel, chief medical officer of Ziopharm Oncology (NASDAQ: ZIOP), plans to step down from his position effective Oct. 26. The Boston cancer drug developer gave no reason for Lebel’s decision to leave the company. In a securities filing, Ziopharm said Lebel gave his notice on Oct. 10. Lebel has been Ziopharm’s chief medical officer since 2015, according to Bloomberg executive profile. In other moves, Ziopharm appointed CEO Laurence Cooper to its board of directors. Ziopharm develops cell and gene therapies to treat cancer.