On May 20, 2021 Salarius Pharmaceuticals, Inc. (Nasdaq: SLRX), a clinical-stage biopharmaceutical company developing potential new medicines for patients with pediatric cancers, solid tumors, and other cancers, reported the publication by the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) of three abstracts accepted for poster presentations during the ASCO (Free ASCO Whitepaper) 2021 Annual Meeting (Press release, Salarius Pharmaceuticals, MAY 20, 2021, View Source [SID1234580429]). ASCO (Free ASCO Whitepaper) 2021 will take place June 4-8, 2021 via a virtual platform.

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Salarius submitted three abstracts disclosing clinical research involving its lead drug candidate, seclidemstat. Details on the presentations can be found below. Key findings include data showing that seclidemstat has a manageable safety profile with no significant hematological toxicities, which can be a limitation for other LSD1 inhibitors. In addition, seclidemstat showed proof-of-concept preliminary drug activity in relapsed/refractory Ewing sarcoma and other advanced cancer patients, including FET-rearranged sarcomas, at or below the recommended phase 2 dose (RP2D), which was established to be 900 mg BID.

"We are excited to have the opportunity to present clinical data regarding safety, dosing, and initial efficacy signals for seclidemstat during ASCO (Free ASCO Whitepaper) 2021," said David Arthur, President and Chief Executive of Salarius Pharmaceuticals. "For the first time, we will report full data and the recommended Phase 2 dose from the recently completed dose-escalation stage of our Phase 1/2 clinical trial in Ewing sarcoma. We will also discuss in more detail the preliminary drug activity data observed in FET-rearranged sarcoma patients from our Advanced Solid Tumor (AST) trial that supports our continued development of seclidemstat as single-agent therapy in select sarcomas."

The full abstracts are available on ASCO (Free ASCO Whitepaper)’s 2021 Meeting Library. Details from the Salarius abstracts are as follows:

Abstract #11514: Phase 1 trial of seclidemstat (SP-2577) in patients with relapsed/refractory Ewing sarcoma
Session Type & Title: Poster Discussion Session, Sarcoma
Presenting Author: Damon R. Reed, M.D., H. Lee Moffitt Cancer Center & Research Institute, Tampa, Florida.
Date & Time: June 4, 2021, 9 a.m. ET
Key Information & Findings: Seclidemstat has a manageable safety profile with proof-of-concept preliminary activity in heavily pretreated patients with relapsed or refractory Ewing sarcoma.

900 mg BID established as the RP2D
A patient dosed at 600 mg BID achieved a reduction in target lesions after 58 days (cycle 2) with further tumor shrinkage after 112 days (cycle 4) and 168 days (cycle 6) for a maximum 76% tumor shrinkage; Coincident new non-target lesion appearance at end of cycle 2
Two additional patients dosed at 600 mg BID and 900 mg BID had overall stable disease
No treatment-related deaths; The most common (>5%) Grade 3 treatment-related adverse events (TRAEs) were vomiting (15%), abdominal pain (11%), and hypokalemia (11%); One patient with Grade 3 pancreatitis reported elevated lipase, a Grade 4 adverse event (AE); No significant hematological TRAES (Grade 3 occurred in <5% of patients)
Abstract #3073: Preliminary efficacy from an ongoing phase 1 dose escalation study of seclidemstat (SP-2577) in patients (pts) with advanced solid tumors (AST)
Session Type & Title: Poster Session, Developmental Therapeutics—Molecularly Targeted Agents and Tumor Biology
Presenting Author: Sant P. Chawla, M.D., Sarcoma Oncology Research Center, Santa Monica, California
Date & Time: Friday, June 4, 2021, 9 a.m. ET
Key Information & Findings: Seclidemstat has shown activity among advanced sarcoma patients with a manageable safety profile. Dose escalation is ongoing and preliminary clinical data supports further exploration in FET-translocated sarcomas as single agent and in combination therapy. Safety data will be presented after completion of Phase 1 dose-escalation.

As of December 30, 2020, 19 patients were enrolled in AST trial, including patients with prostate ovarian, pancreatic, renal, cervical and breast cancer, as well as sarcomas; Patients received a median of four prior systemic treatments
13 patients were evaluable for response after 58 days of treatment (cycle 2); 7 patients had best response of stable disease (SD) with median time to progression (TTP) of 4.3 months, including 3 patients with advanced FET-rearranged sarcomas
All 7 patients were dosed at 300 mg BID or 600 mg BID
The most common Grade 3 TRAEs were gastrointestinal-related and included diarrhea (5.3%) and abdominal pain (5.3%)
No treatment-related deaths and no Grade 4 TRAEs have been reported
Abstract #TPS11577: Phase 1 expansion trial of the LSD1 inhibitor seclidemstat (SP-2577) with and without topotecan and cyclophosphamide (TC) in patients (pts) with relapsed or refractory Ewing sarcoma (ES) and select sarcomas
Session Type & Title: Poster Session, Sarcoma
Presenting Author: Damon Reed, M.D., H. Lee Moffitt Cancer Center & Research Institute, Tampa, Florida.
Date & Time: June 4, 2021, 9 a.m. ET
Key Information: This is an ongoing dose-expansion study assessing seclidemstat at the RP2D (900 mg BID) in two cohorts: a single-agent expansion in select sarcoma patients and a safety lead-in dose escalation and expansion of seclidemstat in combination with topotecan and cyclophosphamide (TC) in Ewing sarcoma patients.

The sarcoma cohort will enroll patients with myxoid liposarcoma or other select sarcomas with FET family translocations, including desmoplastic small round cell tumor (DSRCT); The trial will allow patients treated with one to three prior lines of therapy
The Ewing sarcoma cohort will allow patients treated with up to two prior lines of therapy
Primary objective is safety and tolerability, and secondary objective is efficacy
Recruiting patients across eight U.S. locations
This year, ASCO (Free ASCO Whitepaper) received and reviewed more than 5,400 abstracts for the 2021 Annual Meeting, the world’s largest gathering of physicians, biopharmaceutical companies, researchers, and investors to discuss cancer research and therapeutics. Information about the Annual Meeting may be accessed at View Source