Full Press Release Details
Citius Oncology Highlights Phase 1 Data in an
Investigator-Initiated Study of LYMPHIR (denileukin diftitox-cxdl) in Combination with Pembrolizumab in Recurrent or Refractory
Gynecologic Malignancies
Investigator-initiated study data presented
May 30, 2026, at the American Society of Clinical Oncology (ASCO) Annual Meeting demonstrated durable responses and manageable tolerability
in heavily pre-treated patients
20.5 months of median progression-free survival
observed among 48% of efficacy-evaluable patients achieving clinical benefit (10 of 21)
Responses were observed in patients previously
treated with immune checkpoint inhibitors, including a 33% objective response rate in patients with relapsed or refractory endometrial
CRANFORD, N.J., June 1, 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), today highlighted Phase 1 clinical data presented
May 30, 2026, at the American Society of Clinical Oncology (ASCO) Annual Meeting evaluating LYMPHIR (denileukin diftitox-cxdl) in combination
with pembrolizumab in patients with recurrent or refractory gynecologic malignancies. The poster presentation (Abstract #2564) was presented
by investigators from the University of Pittsburgh Medical Center (UPMC) Magee-Womens Hospital.
"LYMPHIR's ability to transiently
deplete immunosuppressive regulatory T-cells may help address immune resistance in the tumor microenvironment and enhance the effect of
checkpoint inhibitors. The encouraging clinical signals and tolerability profile observed in this study support continued clinical evaluation
of this "chemo-free" immunomodulatory approach, especially in tumors where resistance to checkpoint inhibitors remains a significant
challenge," said Dr. Myron S. Czuczman, Chief Medical Officer of Citius Oncology.
The open-label Phase 1 study evaluated LYMPHIR
in combination with pembrolizumab in 25 heavily pre-treated patients (21 evaluable for efficacy) with recurrent or metastatic solid tumors,
primarily gynecologic malignancies. Enrolled patients had received a median of five prior therapies, and more than half had previously
received anti-PD-1 or PD-L1 therapy.
Key Efficacy and Safety findings presented
Dr. Alexander Olawaiye, a professor and one of
the gynecologic cancer researchers at UPMC Magee-Womens Hospital and lead investigator of the study, added, "Patients with recurrent
gynecologic malignancies who progress following immunotherapy often have limited treatment options. The clinical activity observed with
denileukin diftitox-cxdl plus pembrolizumab, including durable responses and prolonged disease control in heavily pre-treated patients,
is notable. Given the lack of effective salvage treatments for these patients, especially those that have failed prior immune-checkpoint
inhibition, the novel combination of LYMPHIR plus pembrolizumab provides a potential viable therapeutic option. Importantly, the safety
profile observed was manageable in this heavily pre-treated population, supporting continued evaluation in larger studies."
Ongoing translational studies are evaluating the
impact of the combination on regulatory T-cells, immune effector cells, and the tumor microenvironment to help identify potential biomarkers
in order to optimize future development strategies. A Phase 2 expansion study is being planned to further evaluate the combination in
gynecologic cancers, including less heavily pre-treated and prior immunotherapy-exposed patient populations.
This open-label, dose-escalation, investigator-initiated
Phase 1 study (NCT05200559), led by Dr. Alexander B Olawaiye at UPMC Magee-Womens Hospital, enrolled 25 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. Citius Oncology
provided study drug and financial support to the investigator-initiated study; the study was designed, conducted, and analyzed by the
Important note on investigational use: The use
of LYMPHIR in this study was investigational and outside of its FDA-approved indication of relapsed or refractory Stage I-III cutaneous
T-cell lymphoma. LYMPHIR is not approved by the FDA for the treatment of gynecologic malignancies or any solid tumor, and the safety and
efficacy of LYMPHIR in this setting have not been established. This 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. Early-stage clinical data may not be predictive
of results from larger or later-stage studies.
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 in combination with anti-PD-1 checkpoint inhibition may potentially enhance host 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-associated anti-tumor activity is achieved via a direct cytocidal action on IL-2R-expressing tumors and depletion of host
immunosuppressive regulatory T lymphocytes (Tregs).
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.
About Citius Oncology, Inc.
Citius Oncology, Inc. (Nasdaq: CTOR) is a platform
to develop and commercialize novel targeted oncology therapies. In December 2025, Citius Oncology launched LYMPHIR, approved by the FDA
for the treatment of adults with relapsed or refractory Stage I-III CTCL who had had at least one prior systemic therapy. Management
estimates the initial CTCL market for LYMPHIR currently exceeds $400 million, is growing, and is underserved by existing therapies. Robust
intellectual property protections that span orphan drug designation, complex technology, trade secrets and pending patents for immuno-oncology
use as a combination therapy with checkpoint inhibitors would further support Citius Oncology's competitive positioning. For more
information, please visit www.citiusonc.com.
Forward-Looking Statements
This press release may contain "forward-looking
statements" within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934.
Such statements are made based on our expectations and beliefs concerning future events impacting Citius Oncology. You can identify these
statements by the fact that they use words such as "will," "anticipate," "estimate," "expect,"
"plan," "should," and "may" and other words and terms of similar meaning or use of future dates. Forward-looking
statements are based on management's current expectations and are subject to risks and uncertainties that could negatively affect our
business, operating results, financial condition and stock price. Factors that could cause actual results to differ materially from those
currently anticipated are: our need for substantial additional funds and our ability to raise additional money to fund our operations
for at least the next 12 months as a going concern; our ability to successfully commercialize LYMPHIR and establish a sustainable revenue
stream; our ability to regain compliance with Nasdaq's continued listing standards; our ability to obtain, perform under and maintain
third party agreements and relationships, including obtaining a new bulk drug substance supplier; risks relating to the results of research
and development activities, including those from our existing and any new pipeline assets; early-stage clinical data may not be predictive
of results from larger or later-stage studies; our ability to secure and maintain strategic partnerships and expand international access
to LYMPHIR; the estimated markets for LYMPHIR and our product candidates and the acceptance thereof by any market; our ability to use
the latest technology to support our commercialization efforts for LYMPHIR; physician and patient acceptance of LYMPHIR in a competitive
treatment landscape; our reliance on third-party logistics providers, distributors, and specialty pharmacies to support commercial operations;
our ability to educate providers and payers, secure adequate reimbursement, and maintain uninterrupted product supply; post-marketing
requirements and ongoing regulatory compliance related to LYMPHIR; the ability of LYMPHIR and our product candidates to impact the quality
of life of our target patient populations; our ability to procure cGMP commercial-scale supply; risks related to our growth strategy;