EXHIBIT 31.3
CERTIFICATION OF PRINCIPAL EXECUTIVE OFFICER
I, Thomas J. Riga, certify that:
| 1. | I have reviewed this Annual Report on Form 10-K/A of Spectrum Pharmaceuticals, Inc.; |
| 2. | Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report; |
Date: May 1, 2023
| /s/ THOMAS J. RIGA |
| Thomas J. Riga |
| President and Chief Executive Officer |
| (Chief Executive Officer) |