On May 26, 2026 Citius Oncology, Inc. ("Citius Oncology") (Nasdaq: CTOR), an oncology‑focused biopharmaceutical company and majority‑owned subsidiary of Citius Pharmaceuticals, Inc. ("Citius Pharma") (Nasdaq: CTXR), reported that University of Pittsburgh Medical Center’s investigator-initiated trial evaluating LYMPHIR (denileukin diftitox-cxdl) in combination with the PD-1 immune checkpoint inhibitor pembrolizumab (KEYTRUDA) has been selected for poster presentation at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting (ASCO) (Free ASCO Whitepaper), taking place May 29 – June 2, 2026, in Chicago, Illinois.
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The abstract, submitted by investigators at the University of Pittsburgh Medical Center, was selected for presentation from more than 8,500 submissions reviewed by the ASCO (Free ASCO Whitepaper) Scientific Program Committee. The full abstract was made available on May 21, 2026, via the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) website.
"We are pleased to see this investigator-sponsored study selected for presentation at ASCO (Free ASCO Whitepaper), reflecting continued clinical interest in denileukin diftitox-cxdl across multiple tumor types," said Leonard Mazur, Chairman and Chief Executive Officer of Citius Oncology. "We look forward to engaging with the clinical oncology community to discuss the encouraging topline Phase 1 data evaluating Treg cell suppression in combination with checkpoint inhibitors."
Abstract Details:
Abstract Number: 2564
Title: Depletion of T-regulatory cells by denileukin diftitox-cxdl (E7777) in combination with pembrolizumab in relapsed/refractory (r/r) gynecologic malignancies: Phase 1 study results
Session Type: Poster Session – Developmental Therapeutics—Immunotherapy
Poster Board: 354
Date and Time: May 30, 2026, 1:30 PM-4:30 PM CDT
The Phase 1 study evaluated the safety, tolerability, and preliminary activity of denileukin diftitox-cxdl in combination with pembrolizumab in patients with relapsed or refractory gynecologic malignancies.
The ASCO (Free ASCO Whitepaper) Annual Meeting is one of the world’s largest and most influential oncology conferences, bringing together an estimated 35,000 oncology professionals from around the globe. The meeting serves as a premier forum for the presentation of cutting-edge cancer research, with abstracts selected through a highly competitive peer-review process.
About the Study
This open‑label, dose‑escalation, investigator‑initiated Phase 1 study (NCT05200559), led by Dr. Alexander B Olawaiye at UPMC Magee‑Women’s Hospital, enrolled patients with recurrent or metastatic solid tumors who had received at least one prior line of therapy. LYMPHIR was administered intravenously on Days 1–3 of each 21‑day cycle at escalating doses (3, 6, 9, and 12 mcg/kg), along with pembrolizumab (200 mg IV) on Day 1. Patients who completed eight cycles of combination therapy were continued on pembrolizumab monotherapy until disease progression.
The use of LYMPHIR in this study was investigational and outside of its FDA-approved indication. The Phase 1 study was not designed or powered to evaluate clinical efficacy, and no conclusions can be drawn regarding comparative effectiveness or long-term outcomes.
About Gynecologic Cancers
Recurrent or metastatic ovarian and endometrial cancers are two of the most common gynecologic malignancies in the United States. Endometrial cancer is the most frequently diagnosed gynecologic cancer, with an estimated 70,000 new endometrial cancer cases expected in the United States in 20261, while ovarian cancer remains the deadliest with approximately 12,700 deaths per year (51.6%) and approximately 20,000 new diagnoses each year in the United States2. These cancers are often detected at advanced stages, and although many patients initially respond to platinum‑based chemotherapy, most experience relapse and develop resistance. Survival rates in the recurrent setting remain poor, and responses to current immunotherapies such as PD‑1 inhibitors are limited, highlighting a significant unmet need for novel treatment approaches. LYMPHIR’s transient depletion of regulatory T‑cells may enhance anti‑tumor immune responses and help overcome immunotherapy resistance in these difficult‑to‑treat tumors.
About LYMPHIR (denileukin diftitox‑cxdl)
LYMPHIR is a targeted immune therapy for relapsed or refractory cutaneous T-cell lymphoma (CTCL) indicated for use in Stage I-III disease after at least one prior systemic therapy. It is a recombinant fusion protein that combines the IL-2 receptor binding domain with diphtheria toxin (DT) fragments. The agent specifically binds to IL-2 receptors on the cell surface, causing diphtheria toxin fragments that have entered cells to inhibit protein synthesis. After uptake into the cell, the DT fragment is cleaved and the free DT fragments inhibit protein synthesis, resulting in cell death. Denileukin diftitox-cxdl demonstrated the ability to deplete immunosuppressive regulatory T lymphocytes (Tregs) and antitumor activity through a direct cytocidal action on IL-2R-expressing tumors.
In 2021, reformulated denileukin diftitox received regulatory approval in Japan for the treatment of relapsed or refractory CTCL and peripheral T-cell lymphoma (PTCL). Subsequently, in 2021, Citius acquired an exclusive license with rights to develop and commercialize reformulated denileukin diftitox in all markets except for India, Japan and certain parts of Asia. LYMPHIR (denileukin diftitox-cxdl) was approved by the FDA and subsequently launched in the U.S. in December 2025.
(Press release, Citius Oncology, MAY 26, 2026, View Source [SID1234666068])