PUMA BIOTECHNOLOGY, INC.

Evaluation of Disclosure Controls and Procedures

In designing and evaluating the disclosure controls and procedures, management recognized that any controls and procedures, no matter how well designed and operated, can only provide reasonable assurance of achieving the desired control objectives and in reaching a reasonable level of assurance, management was necessarily required to apply its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

Under the supervision and with the participation of our management, including our Chief Executive Officer and Chief Financial Officer, we have evaluated the effectiveness of our disclosure controls and procedures (as defined under Exchange Act Rules 13a-15(e) and 15d-15(e)) as of September 30, 2026. Based on that evaluation, our Chief Executive Officer and Chief Financial Officer have concluded that, as of September 30, 2026, our disclosure controls and procedures were not effective because of the material weakness in internal control over financial reporting described below.

Notwithstanding the existence of this material weakness, management has concluded that our condensed consolidated financial statements included in this Quarterly Report on Form 10-Q present fairly, in all material respects, our financial position, results of operations and cash flows in accordance with U.S. GAAP for each of the periods presented.

Identification of a Material Weakness in Internal Control Over Financial Reporting

During the quarter ended September 30, 2026, management identified a material weakness in our internal control over financial reporting. A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting such that there is a reasonable possibility that a material misstatement of our annual or interim financial statements would not be prevented or detected on a timely basis.

In connection with the implementation of our new Enterprise Resource Planning (ERP) system which was implemented on January 1, 2026, certain Information Technology General Controls (ITGCs) related to user access and program change management did not effectively operate. The material weakness resulted from not having a complete risk assessment process related to the systems development life cycle to identify and timely respond to the risks related to privileged access, user control monitoring and segregation of duties in the affected IT environment, as well as adequate training of personnel related to the ERP implementation and this gave rise to a material weakness in internal control over financial reporting. Specifically:

Manual controls that rely on system-generated data or reports from the affected IT environment or process level automated controls in the affected IT environment were ineffective because they could have been adversely impacted. These control deficiencies identified did not result in misstatements to our annual or interim financial statements; however, the aggregated control deficiencies created a reasonable possibility that a material misstatement of our annual or interim financial statements would not be prevented or detected on a timely basis. As a result, management concluded that a material weakness existed.

Prior-Period Existence and Impact

Following the identification of this material weakness during the quarter ended September 30, 2026, management performed a retrospective evaluation of relevant accounting control activities. Based on this evaluation, management determined that this material weakness also existed as of June 30, 2026, although it was not identified during the prior quarter.

Management has evaluated the impact of this material weakness on our previously issued unaudited condensed consolidated financial statements for the quarterly period ended June 30, 2026, included in our Quarterly Report on Form 10-Q filed on August 6, 2026. Management performed extensive compensating procedures, review of journal entries, access and IT changes during the period when the privileged access and lack of change management monitoring occurred, and concluded that the material weakness did not result in any material misstatements, and no restatement of previously issued financial statements is required.

Management’s Remediation Plan

Under the oversight of the Audit Committee, management is actively engaged in developing and implementing a rigorous plan to remediate the material weakness. Our remediation efforts include the following actions:

We believe these measures will remediate the material weakness. However, the material weakness will not be considered officially remediated until the newly designed controls operate effectively for a sufficient period of time, and management has tested and concluded that they were operating effectively.

Changes in Internal Control Over Financial Reporting

Other than the ongoing deployment, stabilization, and initial post-go-live configurations of our new corporate ERP application suite, there were no changes in our internal control over financial reporting during the quarter ended September 30, 2026, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.