Investigator-initiated Phase 1/2 Clinical Trial Using Salarius Pharmaceuticals’ Seclidemstat in Combination with Azacitidine to Treat Hematologic Cancers Resumes Patient Enrollment

Additional Ewing Sarcoma Patient in Company’s Phase 1/2 Sarcoma Trial Achieves Partial Response; Objective Response Rate Among First-Relapse Ewing Patients Treated with Seclidemstat, Topotecan and Cyclophosphamide Reaches 60%

HOUSTON, Jan. 03, 2024 (GLOBE NEWSWIRE) — Salarius Pharmaceuticals, Inc. (Nasdaq: SLRX) announces that the hematologic cancer Phase 1/2 clinical trial being conducted at the University of Texas MD Anderson Cancer Center (MDACC or MD Anderson) is now listed as active and recruiting on clinical trials.gov – trial NCT04734990. Salarius also announces that an additional Ewing sarcoma patient treated with seclidemstat, topotecan and cyclophosphamide (TC) has achieved a partial response as demonstrated by at least a 30% decrease in the sum of diameters of the patient’s target lesions, bringing the objective response rate (ORR) in Ewing sarcoma first-relapse patients to 60%, with a 60% disease control rate (DCR).

As reported on August 8, 2023, Salarius retained Canaccord Genuity, LLC to lead a comprehensive review of strategic alternatives focusing on maximizing shareholder value. While these efforts are ongoing, the Company continues to support the continuation of its clinical programs, as appropriate.

In October 2022, the FDA placed the MDACC investigator-initiated trial under a partial clinical hold following a suspected unexpected serious adverse reaction (SUSAR) in the FET-rearranged arm of Salarius’ Phase 1/2 trial with seclidemstat in sarcomas. The SUSAR observed in the FET-rearranged patients has not been observed in patients in the MDACC investigator-initiated trial.

“We are pleased that the FDA has removed the partial clinical hold on the MD Anderson trial with seclidemstat in blood cancers, and we are excited about the prospect of MD Anderson enrolling additional patients and building a broader database of patient data,” said David Arthur, president and chief executive officer of Salarius Pharmaceuticals. “MDACC researchers previously reported what we believe are encouraging interim results, and we look forward to learning what potential benefits patients will experience at higher doses of seclidemstat.”

“We are also pleased to see that patients continuing treatment with seclidemstat and TC continue to improve. With our Food and Drug Administration Type B meeting process completed, we plan to file an amended Ewing protocol focusing on first relapse patients, who we believe will benefit from Seclidemstat and TC combination therapy,“ concluded Mr. Arthur.

Seclidemstat is a novel oral reversible inhibitor of the LSD1 enzyme and has received fast track, orphan drug and rare pediatric disease designations for Ewing sarcoma from the FDA. In addition to the MDACC investigator-initiated clinical trial, seclidemstat has been studied in a company-sponsored Phase 1/2 clinical trial evaluating its use in combination with TC for the treatment of relapsed/refractory Ewing sarcoma.

Researchers at MDACC previously reported interim clinical trial results evaluating seclidemstat in combination with azacitidine for the treatment of myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML) patients who relapsed or progressed after hypomethylating agent therapy. Of eight evaluable patients, four (50%) had an objective response. These researchers reported a 90% probability of survival for 11 months in patients receiving seclidemstat plus azacitidine. Typically, overall survival is four to six months after failing therapy with hypomethylating agents.

The Company-sponsored Ewing sarcoma clinical trial focuses on seclidemstat in combination with TC as a treatment for relapsed and refractory Ewing sarcoma. As of December 2023, a total of 13 relapsed Ewing sarcoma patients, including five patients with first relapse and eight patients with second relapse, were enrolled at seclidemstat doses of 600 mg or 900 mg twice daily in combination with TC chemotherapy.

• The five first-relapse patients demonstrated a 60% ORR and a 60% DCR including a complete response and two partial responses. Among the three patients achieving ORR, the median progression-free survival (mPFS) has not been reached with these patients still having disease control and objectives responses at 17.4, 25.7 and 27.2 months, and increasing, after starting seclidemstat + TC combination treatment.
• The eight second-relapse patients demonstrated a 13% ORR, a 25% DCR and a mPFS of 1.6 months (range: 0.0 months to 10.7 months).
• Together the 13 first- and second-relapse patients demonstrated a mPFS of 8.1 months (range: 2.0 months to 27.2 months). Five patients, or 38%, achieved confirmed disease control and progression has not been observed in any of these patients while on study.

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, Salarius’ 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 being developed for the treatment of non-Hodgkin’s lymphoma. Salarius has received financial support from the National Pediatric Cancer Foundation to advance the Ewing sarcoma program and was a recipient of a Product Development Award from the Cancer Prevention and Research Institute of Texas (CPRIT). For more information, please visit salariuspharma.com or follow Salarius on Twitter and LinkedIn.

Forward-Looking Statements
This press release 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 press release are forward-looking statements. These forward-looking statements may be identified by terms such as “will,” “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: Salarius’ expectations regarding the exploration of strategic alternatives, opportunities to extend Salarius’ resources, the future of the Company’s operations and product candidates; the future of the Company’s preclinical studies and clinical trials and development activities; the advantages of protein degraders including the value of SP-3164 as a cancer treatment; 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. Salarius may not actually achieve the plans, carry out the intentions or meet the expectations or objectives disclosed in these 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: the risk that exploration of strategic alternatives may not result in any definitive transaction or enhance stockholder value and may create a distraction or uncertainty that may adversely affect our operating results, business, or investor perceptions; expectations regarding future costs and expenses; our product candidates being in early stages of development; the uncertainty about the paths of our programs and our ability to evaluate and identify a path forward for those programs, particularly given the constraints we have as a small company with limited financial, personnel and other operating resources (including with respect to the allocation of our limited capital and the sufficiency of our capital in the near term for any path we do select); Salarius’ ability to continue as a going concern; the sufficiency of Salarius’ capital resources; availability of suitable third parties with which to conduct contemplated strategic transactions; whether the Company will be able to pursue a strategic transaction, or whether any transaction, if pursued, will be completed successfully and on attractive terms or at all; whether our cash resources will be sufficient to fund the Company’s foreseeable and unforeseeable operating expenses and capital requirements; changes in the Company’s operating plans that may impact its cash expenditures; the uncertainties inherent in research and development, future clinical data and analysis; the risks associated with reductions in workforce, including reduced morale and attrition of additional employees necessary for the strategic reprioritization; future clinical trial results and the impact of such results on Salarius; that the results of studies and clinical trials may not be predictive of future clinical trial results; 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, 2022, 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 press release speak only as of the date of this press release 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
kgolodetz@lhai.com
212-838-3777