Salarius Pharmaceuticals Presents SP-3164 Data Demonstrating Activity in Preclinical Lymphoma Models at the American Society of Hematology Annual Meeting

Significant single-agent activity in diffuse large B-cell lymphoma (DLBCL) cell models and in mouse model showed superiority to lenalidomide (Revlimid^®)

Synergistic activity with rituximab in DLBCL mouse model resulted in complete regressions and was superior to the approved regimen, lenalidomide and rituximab

Company planning to submit IND and begin a Phase 1 trial in 2023

HOUSTON, Dec. 13, 2022 (GLOBE NEWSWIRE) — Salarius Pharmaceuticals, Inc. (NASDAQ: SLRX), a clinical-stage biopharmaceutical company using protein inhibition and protein degradation to develop cancer therapies for patients in need of new treatment options, announces that yesterday Daniela Santiesteban, Ph.D., Salarius’ director of targeted protein degradation development, presented positive SP-3164 preclinical data at the 64^th American Society of Hematology (ASH) Annual Meeting and Exposition underway in New Orleans and virtually.

SP-3164 is an oral, next-generation molecular glue that uses deuterium to stabilize the preferred (S)-enantiomer of avadomide and thereby prevents interconversion into the unwanted (R)-enantiomer of avadomide. Avadomide is an extensively studied clinical compound that has demonstrated encouraging single-agent and combination-therapy efficacy in non-Hodgkin’s lymphomas (NHL) and other hematologic malignancies. In addition, published DLBCL avadomide clinical data showed patients with an identifiable gene signature had clinically meaningful improvements in overall response rates, suggesting that Salarius may be able to select patients more likely to respond to SP-3164 treatment. This, along with the data presented at ASH showing compelling SP-3164 activity in lymphoma models, supports SP-3164’s potential in NHL for the clinical trial planned for 2023.

The poster – titled “SP-3164, a Novel Cereblon-Binding Protein Degrader, Shows Activity in Preclinical Lymphoma Models” – demonstrated that in lymphoma cells, SP-3164 interacts with the cereblon component of a CRL4 E3 ligase, inducing recruitment and subsequent degradation of the hematological transcription factors Ikaros and Aiolos, which play a critical role in regulating B and T cell development. Like other Ikaros and Aiolos degraders such as lenalidomide and avadomide, SP-3164 demonstrates compelling activity in NHL and may have potential safety and efficacy advantages over other molecular glues.

Data highlights included in the poster, available here, include:

• SP-3164 induced rapid and efficient Ikaros degradation compared to other studied molecular glues
• SP-3164 exhibited antiproliferative effects across several NHL cell lines
• SP-3164 pharmacokinetics showed exclusive exposure to the preferred (S)-enantiomer
• SP-3164 demonstrated single-agent activity in DLBCL mouse model and superiority to lenalidomide (Revlimid^®)
• SP-3164 resulted in complete regressions in 50% of mice when treated in combination with rituximab in a DLBCL mouse model and performed significantly better than the approved regimen of lenalidomide (Revlimid^®) and rituximab

“Having our research selected for a presentation at the prestigious ASH conference provides further visibility into what we believe is compelling preclinical data being generated with SP-3164,” said David Arthur, president and chief executive officer of Salarius Pharmaceuticals. “We plan to begin a Phase 1 dose-escalation study with SP-3164 in hematological cancers next year and have already completed the FDA pre-Investigational New Drug (IND) meeting process. We continue to believe SP-3164 will be the first stabilized preferred enantiomer molecular glue to enter clinical development, with the potential to build upon a $16 billion market established with first-generation molecular glues.”

About Salarius Pharmaceuticals
Salarius Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company developing therapies for patients with cancer in need of new treatment options. Salarius’ product portfolio includes seclidemstat, the company’s lead candidate, which is being studied as a potential treatment for pediatric cancers, sarcomas and other cancers with limited treatment options, and SP-3164, an oral small molecule protein degrader. Seclidemstat is currently in a Phase 1/2 clinical trial for relapsed/refractory Ewing sarcoma and certain additional sarcomas that share a similar biology. This trial is currently on a partial clinical hold and is not enrolling new patients. Seclidemstat has received fast track, orphan drug and rare pediatric disease designations for Ewing sarcoma from the U.S. Food and Drug Administration. Salarius is also exploring seclidemstat’s potential in several cancers with high unmet medical need, with an investigator-initiated Phase 1/2 clinical study in hematologic cancers at MD Anderson Cancer Center. This trial is currently on a voluntary pause and is not enrolling new patients. Salarius has received financial support from the National Pediatric Cancer Foundation to advance the Ewing program and was a recipient of a Product Development Award from the Cancer Prevention and Research Institute of Texas (CPRIT). SP-3164 is currently in IND-enabling studies and anticipated to enter the clinic in 2023. For more information, please visit salariuspharma.com or follow Salarius on Twitter and LinkedIn.

Forward-Looking Statements
This letter contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. All statements, other than statements of historical facts, included in this letter are forward-looking statements. These forward-looking statements may be identified by terms such as “believe,” “developing,” “expect,” “may,” “progress,” “potential,” “could,” “look forward,” “encouraging,” “might,” “should,” and similar terms or expressions or the negative thereof. Examples of such statements include, but are not limited to, statements relating to the following: the future of the company’s Phase 1/2 trial of seclidemstat as a treatment for Ewing sarcoma and FET-rearranged sarcomas following the recently announced suspected unexpected severe adverse reaction (SUSAR) event and resulting partial clinical hold by the U.S. Food and Drug Administration (FDA); impact that the addition of new clinical sites will have on the development of Salarius’ product candidates; the timing of Salarius’ IND submissions to the FDA and subsequent timing for initiating clinical trials; interim data related to Salarius’ clinical trials, including the timing of when such data is available and made public; Salarius’ growth strategy; the value of seclidemstat as a treatment for Ewing sarcoma, Ewing-related sarcomas, and other cancers and its ability to improve the life of patients; expanding the scope of Salarius’ research and focus to high unmet need patient populations; milestones of Salarius’ current and future clinical trials, including the timing of data readouts. Salarius may not actually achieve the plans, carry out the intentions or meet the expectations or objectives disclosed in the forward-looking statements. You should not place undue reliance on these forward-looking statements. These statements are subject to risks and uncertainties which could cause actual results and performance to differ materially from those discussed in the forward-looking statements. These risks and uncertainties include, but are not limited to, the following: FDA may impose additional restrictions on the company’s Phase 1/2 trial of seclidemstat as a treatment for Ewing sarcoma and FET-rearranged sarcomas following the SUSAR, including a partial or full clinical hold; Salarius’ ability to resume enrollment in the clinical trial following its review of the available data surrounding the SUSAR; the sufficiency of Salarius’ capital resources; the ability of, and need for, Salarius to raise additional capital to meet Salarius’ business operational needs and to achieve its business objectives and strategy; future clinical trial results and impact of results on Salarius; that the results of studies and clinical trials may not be predictive of future clinical trial results; risks related to the drug development and the regulatory approval process; the competitive landscape and other industry-related risks; and other risks described in Salarius’ filings with the Securities and Exchange Commission, including its Annual Report on Form 10-K for the fiscal year ended December 31, 2021, as revised or supplemented by its Quarterly Reports on Form 10-Q and other documents filed with the SEC. The forward-looking statements contained in this letter speak only as of the date of this letter and are based on management’s assumptions and estimates as of such date. Salarius disclaims any intent or obligation to update these forward-looking statements to reflect events or circumstances that exist after the date on which they were made.

CONTACT:

LHA Investor Relations
Kim Sutton Golodetz
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