Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) x QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2019 (Exact name of registrant as specified in its charter) (State or other jurisdiction of (I.R.S. Employer incorporation or organization) Identification No.) Delaware 22-3627252 375 Pheasant Run, Newtown, PA 18940 (Address of principal executive offices) (Zip Code) Regi ...

ý ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2018 Or Use these links to rapidly review the document TABLE OF CONTENTS ONCONOVA THERAPEUTICS, INC. AND SUBSIDIARIES Index to Consolidated Financial Statements Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-K (Mark one) o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition peri ...