As filed with the Securities and Exchange Commission on July 31, 2025 Registration No. 333-284368 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO. 4 TO FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 SALARIUS PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) (State or other jurisdiction of incorporation or organization) (Primary Standard Industrial Classification Code Number) 2450 Holcombe Blvd. Suite X Houston, TX 77021 713-91 ...

Core Points - Salarius Pharmaceuticals received an extension from Nasdaq to regain compliance with listing rules by late July 2025 and early August 2025 [1][2] - The company is in the process of merging with Decoy Therapeutics, a preclinical biopharmaceutical company focused on peptide conjugate therapeutics [3][4] - The merger is expected to create value through Decoy's innovative pipeline targeting respiratory infectious diseases and GI oncology [4][6] Compliance with Nasdaq - Salarius was notified on April 23, 2025, that it was not compliant with Nasdaq Listing Rule 5550(a)(2) due to a closing bid price below $1.00 per share for 30 consecutive business days [2] - The company also failed to meet the requirement of maintaining at least $2.5 million in stockholders' equity as per Nasdaq Listing Rule 5550(b)(1) [2] - An extension was granted contingent on achieving compliance milestones by early July and early August 2025 [2] Merger with Decoy Therapeutics - The merger agreement was announced on January 13, 2025, and will involve Decoy merging with a wholly owned subsidiary of Salarius [3][11] - The combined company will be named Decoy Therapeutics and will focus on advancing Decoy's peptide conjugate therapeutics and Salarius' SP-3164 [4][11] - Following the merger, Decoy investors are expected to own approximately 92.4% of the merged company, while Salarius stockholders will own about 7.6% [11] Product Pipeline and Development - Decoy plans to advance its lead asset, a pan-coronavirus antiviral, to the FDA for an Investigational New Drug (IND) application within the next 12 months [6] - The company is also working on other antiviral programs and peptide drug conjugates targeting GI cancers [6] - Salarius' seclidemstat is being evaluated in a Phase 1/2 clinical study for myelodysplastic syndrome and chronic myelomonocytic leukemia [7][10] About Decoy Therapeutics - Decoy is leveraging machine learning and AI to design and manufacture peptide conjugate drug candidates targeting unmet medical needs [8] - The company has received funding from various sources, including institutional investors and government programs [8] About Salarius Pharmaceuticals - Salarius is a clinical-stage biopharmaceutical company with two drug candidates focused on cancer treatment [9][10] - The company has received financial support for its lead candidate, seclidemstat, from various organizations [10]