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# Regulatory Review Period Determined for Zydelig
- URL: https://www.fdaweb.com/regulatory-review-period-determined-for-zydelig/
- Published: 2018-02-23T12:00:00.000Z
- Updated: 2026-09-14T23:25:03.000Z
- Author: David McFarland
- Tags: FDA Policy/General, #legacy-id-D5140834

*Federal Register* notice: FDA has determined for patent extension purposes that the regulatory review period for ICOS Corp.'s Zydelig (idelalisib) is 2,247 days. Of this time, 2,017 days occurred during the testing phase and 230 days during the approval phase. Zydelig is indicated for treating patients with relapsed chronic lymphocytic leukemia in combination with rituximab, in patients for whom rituximab alone would be considered appropriate therapy due to other co-morbidities. To view the notice, click [here](https://www.gpo.gov/fdsys/pkg/FR-2018-02-23/pdf/2018-03701.pdf?ref=fdaweb.com).