Senhwa Biosciences Reports Positive Phase 1 Data of CX-5461 in Patients With Advanced Solid Tumors at 2019 SABCS

Evidence of human efficacy observed in patients with specific biomarkers and refractory to standard treatments including platinum and other chemotherapeutics

G-quadruplex stabilizers are a novel class of therapy that accelerate double-stranded DNA (dsDNA) breaks

Recommended Phase 2 dose (RP2D) was determined

TAIPEI and SAN DIEGO, Dec. 13, 2019 /PRNewswire/ — Senhwa Biosciences Inc. (TPEx: 6492), a clinical stage biopharmaceutical company focused on next generation DNA Damage Response (DDR) therapeutics for the treatment of cancer, today announced positive results from its Phase 1 trial of CX-5461. CX-5461 is the company’s First-in-Class G-quadruplex stabilizer. The patients enrolled in the study all presented with advanced solid tumors, with no other available treatment options.

In 2016, CX-5461 was awarded a Stand Up to Cancer Dream Team Grant. Phase 1 clinical findings were featured within a spotlighted presentation at the annual 2019 San Antonio Breast Cancer Symposium (SABCS) by Senhwa’s clinical partner, Canadian Cancer Trials Group (CCTG).

"CX-5461 has demonstrated clinically meaningful and durable benefits in patients with specific tumor biomarkers that are also resistant to platinum and other chemotherapeutics. The Phase 1 study has validated CX-5461 as a G-quadruplex stabilizer within a novel class of therapy that accelerates dsDNA breaks and has proven human efficacy across certain tumor types," said Dr. Tai-Sen Soong, CEO of Senhwa Biosciences. The clinical results exhibited that CX-5461 has the potential to rescue cancer patients who have developed resistance to platinum and other chemotherapeutics. Additional clinical trials are being planned to further confirm the efficacy seen.

The Phase 1 dose escalation portion of the CX-5461 trial was designed to determine Recommended Phase 2 Dose (RP2D), as well as evaluate preliminary anti-tumor activity of a single agent (CX-5461), in patients with metastatic and recurrent solid tumors. 41 patients enrolled in the study, due to the fact that all available treatments had failed to treat their malignancies, and 40 of those patients had been treated with different dose levels of CX-5461.

As of the November 25th, 2019 data cutoff, the study findings showed:

  • 32 of 41 patients enrolled were evaluable patients, the median age was 53 (range 25-73).
  • Of the evaluable patients, 24 had attempted 3 or more prior treatment regimens for their disease.
  • In this heavily pre-treated Phase 1 population, responses were seen with CX-5461 within the dose range of 100mg/m2 to 650mg/m2.
  • Patients presented with a range of solid tumors, including metastatic breast cancer (47.5%), Ovary (17.5%), Pancreas (7.5%), Non-small-cell Lung Cancer (5%) and others (22.5%)

Preliminary Safety Analysis:

  • CX-5461 was well tolerated:
    – Treatment-related Adverse Events (AEs ≥20%) were photosensitivity of the skin (58%); eye disorders (including Photosensitivity 20%); nausea (70%); headache (25%); fatigue (73%).
    – No Dose Limited Toxicities (DLTs) observed to date. There were 6 treatment-related non-DLT grade 3 photosensitivity events.
    – The RP2D was determined to be 475mg/m2 on days 1, 8 and 15 of a 4-week cycle.
  • UV avoidance and protection measures were successful in mitigating risks associated with photo toxicity.

Preliminary Efficacy Analysis:

  • As of the data cutoff, 32 patients were evaluable for response. In terms of best response, 4 patients (3 breast cancer, 1 ovary) had a confirmed Partial Response with an additional 4 patients had durable Stable Disease.
  • Heavily pre-treated (including platinum resistant) patients with specific biomarkers showed significant tumor shrinkage and maintained significant treatment duration in the trial. The maximum duration was 16 cycles, with 28 days per cycle.
  • G-quadruplex stabilizers are a novel class of therapy that has demonstrated accelerated dsDNA breaks.

About CX-5461

CX-5461 is designed to stabilize DNA G-quadruplexes of cancer cells and leads to disruption of the cell’s replication fork. While acting in concert with HR (Homologous Recombination) pathway deficiency, such as BRCA1/2 mutations, replication forks stall and cause DNA breaks, resulting in cancer cell death. CX-5461 in combination with HRD (Homologous Recombination Deficiency) tumors may be exploited through a synthetic lethality approach, targeting DNA repair defects in HRD tumors.

About Senhwa

Senhwa Biosciences, Inc. (TPEx: 6492), is a leading clinical stage company focused on developing First-in-Class, Next-Generation DNA Damage Response therapeutics for patients with unmet medical needs in oncology. Headquartered in Taiwan, with a vital operational base in San Diego, California, the Senhwa Team is well positioned to oversee the development of their compounds.

Development is currently focused on two lead products Silmitasertib and CX-5461, both with novel mechanisms of action and for multiple indications. Clinical trials are ongoing in Australia, Canada, United States, Korea and Taiwan.

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Source: Senhwa Biosciences Reports Positive Phase 1 Data of CX-5461 in Patients With Advanced Solid Tumors at 2019 SABCS