Barbara Weber, the Third Rock Ventures partner who has been serving as interim CEO of Tango Therapeutics, is now formally the company’s chief executive. Weber will also continue as a partner at Third Rock, the venture capital firm that incubated the cancer drug developer. Cambridge, MA-based Tango spun out of Third Rock in March, backed by a $55 million Series A investment round. Before joining Third Rock, Weber held senior leadership positions in oncology research at Novartis (NYSE: [[ticker:NVS]]) and GlaxoSmithKline (NYSE: [[ticker:GSK]]).