CRANFORD, New Jersey, May 26, 2026
Citius Oncology, Inc. has announced that new Phase 1 clinical study data evaluating LYMPHIR® (denileukin diftitox-cxdl) in combination with KEYTRUDA® (pembrolizumab) will be presented at the prestigious 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. The investigator-initiated study, conducted by researchers at the University of Pittsburgh Medical Center (UPMC), highlights the growing clinical interest in combining targeted immune therapies with checkpoint inhibitors to improve treatment outcomes for patients with difficult-to-treat cancers.
According to the company, the Phase 1 trial demonstrated a 24% objective response rate, an average 21.1-month duration of response among responders, and favorable safety findings in patients with relapsed or refractory gynecologic malignancies. The study evaluated LYMPHIR in combination with pembrolizumab and explored the therapy’s potential role in suppressing immunosuppressive regulatory T-cells (Tregs) to enhance anti-tumor immune responses. The abstract was selected for presentation from more than 8,500 submissions reviewed by the ASCO Scientific Program Committee, underscoring the scientific significance of the findings.
LYMPHIR Combination Therapy Shows Immunotherapy Potential
The open-label, dose-escalation Phase 1 clinical study evaluated escalating doses of LYMPHIR administered intravenously alongside pembrolizumab in patients with recurrent or metastatic solid tumors who had previously received at least one line of therapy. Researchers investigated safety, tolerability, and preliminary anti-cancer activity in relapsed or refractory gynecologic cancers including ovarian and endometrial malignancies.
Citius Oncology stated that the findings suggest LYMPHIR may help augment the efficacy of immune checkpoint inhibitors by temporarily depleting regulatory T-cells, which are known to suppress anti-tumor immune activity within the tumor microenvironment. By reducing Treg-mediated immune suppression, investigators believe the combination may improve the body’s ability to mount a stronger immune response against cancer cells.
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Leonard Mazur, Chairman and Chief Executive Officer of Citius Oncology, stated that the ASCO presentation reflects continued clinical interest in denileukin diftitox-cxdl across multiple tumor types. The company believes the data support further exploration of LYMPHIR beyond its currently approved indication in cutaneous T-cell lymphoma (CTCL).
ASCO Presentation Highlights Expanding Oncology Applications
The ASCO Annual Meeting is widely regarded as one of the world’s most influential oncology conferences, attracting approximately 35,000 cancer specialists, researchers, pharmaceutical companies, and healthcare professionals from around the globe. Selection for presentation at the event is highly competitive and often signals growing scientific and commercial interest in emerging oncology therapies.
The study, led by Dr. Alexander B. Olawaiye at UPMC Magee-Womens Hospital, investigated the combination treatment in patients with advanced gynecologic malignancies where current therapeutic options remain limited. Ovarian and endometrial cancers continue representing significant unmet medical needs, particularly in recurrent or treatment-resistant settings where responses to existing immunotherapies are often modest.
Researchers noted that many gynecologic cancers develop resistance to platinum-based chemotherapy and PD-1 inhibitors over time, creating demand for new immuno-oncology approaches capable of overcoming treatment resistance and improving survival outcomes.
LYMPHIR Expands Presence in Immuno-Oncology Market
LYMPHIR is currently approved by the U.S. Food and Drug Administration (FDA) for the treatment of adults with relapsed or refractory Stage I–III CTCL after at least one prior systemic therapy. The therapy was officially launched in the United States in December 2025 following FDA approval and represents a key commercial product for Citius Oncology’s expanding immuno-oncology portfolio.
The recombinant fusion protein combines an interleukin-2 receptor binding domain with diphtheria toxin fragments, enabling targeted destruction of IL-2 receptor-expressing tumor cells while also depleting immunosuppressive Tregs. Analysts believe the therapy’s dual mechanism of action may create broader opportunities in combination immunotherapy strategies across multiple solid tumor indications.
As oncology companies increasingly focus on precision immunotherapies and combination treatment regimens, the latest Phase 1 findings position LYMPHIR as a potentially important contributor within the rapidly evolving immuno-oncology landscape.
Source: Citius Oncology press release
