TAIPEI, Aug. 6, 2026 /PRNewswire/ — Senhwa Biosciences, Inc. (TPEx: 6492) today announced that the Taiwan Food and Drug Administration (TFDA) has cleared the Company’s multicenter Phase 1b/2a clinical trial evaluating its investigational drug pidnarulex (CX-5461) in combination with a marketed PD-1 immune checkpoint inhibitor. The TFDA clearance follows clearance by the U.S. Food and Drug Administration (FDA) in June 2026, enabling the study to proceed in both Taiwan and the United States. This marks an important step in the development of CX-5461 from a DNA-targeting drug candidate into a potential immuno-oncology combination platform.

The Phase 1b/2a study is designed to assess the safety, tolerability, and preliminary antitumor activity of the combination in patients with advanced solid tumors. The study will enroll patients with pancreatic cancer, colorectal cancer, and melanoma, including patients whose disease has developed resistance to prior immune checkpoint inhibitor therapy—settings in which effective treatment options remain limited.

PD-1 and PD-L1 immune checkpoint inhibitors have transformed cancer care over the past decade. However, a substantial proportion of patients either do not respond initially or eventually develop resistance. In many so-called immune-cold tumors, limited immune-cell infiltration, insufficient antigen presentation, and an immunosuppressive tumor microenvironment can prevent the immune system from mounting an effective response, even when the PD-1 pathway is blocked. Overcoming these barriers and extending the reach of existing checkpoint therapies have therefore become central priorities in immuno-oncology research.

Pidnarulex (CX-5461) is Senhwa’s first-in-class investigational agent designed to induce DNA replication stress and DNA damage responses in cancer cells. Emerging research suggests that these mechanisms may not only directly impair tumor-cell survival but also promote immunogenic cell death, activate innate immune signaling, and increase immune activity within the tumor microenvironment. These potential effects provide the scientific rationale for evaluating whether CX-5461 can sensitize tumors to PD-1 blockade.

The study will investigate whether CX-5461 can favorably alter the tumor immune microenvironment, increase immune-cell infiltration and antigen presentation, and make immune-cold tumors more recognizable and vulnerable to immune attack. In patients whose disease has become resistant to immune checkpoint inhibition, the study will also explore whether the combination can restore antitumor immune activity. These potential effects remain clinical hypotheses and have not yet been established in patients.

The clinical program also reflects a broader shift across the biopharmaceutical industry. As immune checkpoint inhibitors become established backbones of cancer treatment, research and business development are increasingly focused on complementary agents that may broaden or deepen responses to existing PD-1 therapies, particularly in immune-cold and treatment-resistant tumors. Under Senhwa’s collaboration model, a global pharmaceutical company is supplying the marketed PD-1 inhibitor, while Senhwa leads the global and regulatory activities for the study.

Advancing a first-in-human combination study with a marketed immunotherapy, in collaboration with an experienced global pharmaceutical company, provides an internationally aligned framework for evaluating CX-5461 as a potential combination partner. Together with regulatory clearance in both the United States and Taiwan, the collaboration may increase the global visibility of CX-5461 and support future clinical development and partnering opportunities.

The strategic significance of the trial extends beyond a single combination regimen. If clinical data support the safety, immune-sensitizing activity, and preliminary efficacy of CX-5461, the asset could potentially be evaluated with additional PD-1 or PD-L1 therapies, in other tumor types, and alongside modalities such as antibody-drug conjugates, radiotherapy, and photodynamic therapy. This could position CX-5461 as a platform asset with potential applications across multiple cancers, products, and treatment modalities.

Senhwa will continue to advance study activation and patient enrollment and will use emerging safety, pharmacologic, efficacy, and biomarker data to identify the patient populations and development strategies most likely to benefit. The Company cautions that this is an early-stage clinical trial primarily intended to evaluate safety, tolerability, and preliminary efficacy. Whether CX-5461 can improve responses to PD-1 therapy, remodel the tumor immune microenvironment, or help overcome acquired resistance must be established through clinical data.

About Senhwa Biosciences

Senhwa Biosciences, Inc. is a Taiwan-based biotechnology company developing novel oncology therapeutics for cancers with significant unmet medical needs. Its pipeline includes CX-5461 and CX-4945, which are being evaluated in solid tumors and hematologic malignancies through international clinical and research collaborations. For more information, visit www.senhwabio.com.

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