Citius Oncology (CTOR) reports positive Phase 1 LYMPHIR combo results in gynecologic cancers
Rhea-AI Filing Summary
Citius Oncology, Inc. reported positive topline results from an investigator-initiated Phase 1 trial of LYMPHIR™ (denileukin diftitox-cxdl) combined with pembrolizumab (KEYTRUDA®) in patients with recurrent or refractory gynecologic cancers, including ovarian and endometrial malignancies.
Among 25 evaluable patients, no unexpected safety signals or serious immune-related adverse events were seen at any dose level. In 21 evaluable patients, the trial showed a 24% objective response rate and a 48% clinical benefit rate, defined as complete or partial response or stable disease for at least six months. Full safety and efficacy data are planned for presentation at an international cancer conference.
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Insights
Early Phase 1 data suggest activity and tolerability for LYMPHIR plus pembrolizumab in hard‑to‑treat gynecologic cancers.
The Phase 1, dose‑escalation study of LYMPHIR with pembrolizumab in relapsed or refractory gynecologic cancers reported no unexpected safety signals or serious immune-related adverse events across 25 evaluable patients. This is important because these patients are heavily pretreated and often have limited options.
Among 21 evaluable patients, the combination showed a 24% objective response rate and a 48% clinical benefit rate, defined to include durable stable disease of six months or longer. Investigators emphasized the encouraging efficacy signal in a setting where immuno-oncology agents historically have had limited impact, while noting that this Phase 1 trial was not designed or powered to assess comparative effectiveness or long-term outcomes.
The study also helped establish a recommended LYMPHIR dose for potential Phase 2 testing. Detailed safety and efficacy data are expected to be presented at an international cancer conference later in
UNITED STATES
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Washington, D.C. 20549
FORM
CURRENT REPORT
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Item 8.01 Other Events.
On March 10, 2026, we issued a press release announcing positive topline results from a completed investigator-initiated Phase 1 clinical trial conducted by University of Pittsburgh investigators. This study evaluated the direct T-regulatory (Treg) cell depletion activity of LYMPHIR™ (denileukin diftitox-cxdl) in combination with the PD-1 immune checkpoint inhibitor pembrolizumab (KEYTRUDA®) in patients with recurrent or refractory gynecologic cancers, including ovarian and endometrial malignancies. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.
Item 9.01. Financial Statements and Exhibits.
(d) Exhibits
| Exhibit No. | Description | |
| 99.1 | Press release, dated March 10, 2026. | |
| 104 | Cover Page Interactive Data File, formatted in Inline Extensible Business Reporting Language (iXBRL). |
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SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
| CITIUS ONCOLOGY, INC. | |
| Date: March 10, 2026 | /s/ Leonard Mazur |
| Leonard Mazur | |
| Chairman and Chief Executive Officer |
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Exhibit 99.1
Citius Oncology Announces Positive Topline Results from Investigator-Initiated Phase 1 Study of LYMPHIR™ in Combination with Pembrolizumab in Relapsed or Refractory Gynecologic Cancers
Study data from patients with relapsed or refractory gynecologic cancers signals the potential of LYMPHIR to augment immune checkpoint inhibitor efficacy
Topline data of University of Pittsburgh-led trial to be presented at an upcoming international cancer conference later this year
CRANFORD, N.J., March 10, 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 announced positive topline results from a completed investigator-initiated Phase 1 clinical trial conducted by University of Pittsburgh investigators. This study evaluated the direct T-regulatory (Treg) cell depletion activity of LYMPHIR™ (denileukin diftitox-cxdl) in combination with the PD-1 immune checkpoint inhibitor pembrolizumab (KEYTRUDA®) in patients with recurrent or refractory gynecologic cancers, including ovarian and endometrial malignancies.
Patients with relapsed or refractory gynecological cancer have poor prognoses and very limited treatment options. This dose-escalation Phase 1 non-chemotherapy based clinical study aimed to establish a recommended dose of LYMPHIR in combination with pembrolizumab for a Phase 2 study. In 25 evaluable patients, no unexpected safety signals or serious immune-related adverse events were observed at any dose level.
“We are encouraged by the favorable safety profile and sustained disease control observed in this heavily pretreated patient population. Evidence from the study suggests augmented anti-tumor activity when LYMPHIR is combined with KEYTRUDA and warrants further exploration in Phase 2 settings,” stated Dr. Myron Czuczman, Executive Vice President and Chief Medical Officer of Citius Oncology and Citius Pharma.
The trial explored efficacy and demonstrated a 24 % objective response rate (ORR) and a 48 % clinical benefit rate (CBR, defined as complete response, partial response and/or stable disease for six months or greater) among 21 evaluable patients. Full safety and clinical efficacy results are expected to be presented at an international cancer conference later this year.
“The efficacy signal shown by this combination is incredibly exciting considering the minimal impact immuno-oncology has made in ovarian cancer thus far. If these findings are confirmed in subsequent studies, we may have a transformational therapy on our hands,” said Dr. Alexander Olawaiye, principal investigator of the study.
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 cases expected in 20261, while ovarian cancer remains the deadliest with approximately 12,700 deaths per year (51.6% 5 year survival) and approximately 20,000 new diagnoses each year2. 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, 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 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.
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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 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: 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 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; the estimated markets for LYMPHIR and our product candidates and the acceptance thereof by any market; our ability to secure strategic partnerships and expand international access to LYMPHIR; our ability to maintain Nasdaq’s continued listing standards; 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; our ability to obtain, perform under and maintain financing and strategic agreements and relationships; market and other conditions; risks related to our growth strategy; patent and intellectual property matters; government regulation; as well as other risks described in our Securities and Exchange Commission (“SEC”) filings. These risks have been and may be further impacted by any future public health risks. Accordingly, these forward-looking statements do not constitute guarantees of future performance, and you are cautioned not to place undue reliance on these forward-looking statements. Risks regarding our business are described in detail in our SEC filings which are available on the SEC’s website at www.sec.gov, including in Citius Oncology’s Annual Report on Form 10-K for the year ended September 30, 2025, filed with the SEC on December 23, 2025. These forward-looking statements speak only as of the date hereof, and we expressly disclaim any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in our expectations or any changes in events, conditions or circumstances on which any such statement is based, except as required by law.
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REFERENCES:
| 1. | American Cancer Society. Cancer Facts & Figures 2026 (projected). Atlanta: American Cancer Society; 2026. https://www.cancer.org/cancer/types/endometrial-cancer/about/key-statistics.html |
| 2. | National Cancer Institute. Surveillance, Epidemiology, and End Results Program (SEER). Cancer Stat Facts: Uterine and Ovarian Cancer. https://seer.cancer.gov/statfacts/html/ovary.html |
KEYTRUDA® is a registered trademark of Merck & Co., Inc.
LYMPHIR™ (denileukin diftitox-cxdl)
INDICATION
LYMPHIR is an IL2-receptor-directed cytotoxin indicated for the treatment of adult patients with r/r Stage I-III cutaneous T-cell lymphoma (CTCL) after at least one prior systemic therapy.
IMPORTANT SAFETY INFORMATION
BOXED WARNING: CAPILLARY LEAK SYNDROME
Capillary leak syndrome (CLS), including life-threatening or fatal reactions, can occur in patients receiving LYMPHIR. Monitor patients for signs and symptoms of CLS during treatment. Withhold LYMPHIR until CLS resolves, or permanently discontinue based on severity.
WARNINGS AND PRECAUTIONS
Capillary Leak Syndrome
LYMPHIR can cause capillary leak syndrome (CLS), including life-threatening or fatal reactions. CLS was defined in the clinical trials as the occurrence of at least 2 of the following symptoms at any time during LYMPHIR therapy: hypotension, edema, and serum albumin <3 g/dL. These symptoms were not required to occur simultaneously to be characterized as capillary leak syndrome.
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As defined, CLS occurred in 27% of patients in the pooled population across 3 clinical trials, including 8% with Grade 3. There was one (0.8%) fatal occurrence of CLS. Of the patients with CLS, 22% had recurrence. The majority of CLS events (81%) occurred within the first 2 cycles of treatment. The median time to onset from Cycle 1, Day 1 was 6.5 days (range: 1 to 77), the median duration of CLS was 14 days (range: 2 to 40), and 75% of patients had resolution. The most common symptoms included edema, hypoalbuminemia, and hypotension. Pleural effusion, pericardial effusion, and dehydration also occurred.
Regularly assess patients for weight gain, new onset or worsening of edema, dyspnea, and hypotension (including orthostatic changes). Monitor serum albumin levels prior to the initiation of each cycle of therapy and more often as clinically indicated.
Withhold, reduce dose, or permanently discontinue based on severity. If LYMPHIR is withheld, resume LYMPHIR following resolution of CLS and when serum albumin is greater than or equal to 3 g/dL.
Visual Impairment
LYMPHIR can cause serious visual impairment, including changes in visual acuity and color vision. In the pooled population across 3 clinical trials, visual impairment occurred in 9%, with Grade 1 in 8% and Grade 2 in 1%. The most commonly reported symptom was blurred vision. Of the patients with visual impairment, 67% had resolution of their visual impairment.
Perform baseline ophthalmic examination and monitor as clinically indicated. If patients experience symptoms of visual impairment, such as changes in visual acuity, changes in color vision, or blurred vision, refer for ophthalmologic evaluation.
Withhold LYMPHIR until visual impairment resolves or permanently discontinue based on severity.
Infusion-Related Reactions
LYMPHIR can cause serious infusion-related reactions. Infusion-related reactions were reported in 69% of patients in the pooled population across 3 clinical trials of patients who received LYMPHIR, with Grade 3 infusion-related reactions in 3.4%. Eighty-three percent of infusion-related reactions occurred in Cycles 1 and 2. The most common symptoms included nausea, fatigue, chills, musculoskeletal pain, vomiting, fever, and arthralgia.
Premedicate patients for the first three cycles prior to starting a LYMPHIR infusion. Monitor patients frequently during infusion. For Grade 2 or higher infusion reactions, premedicate at least 30 minutes prior to each subsequent infusion with a systemic steroid for at least 3 cycles.
Interrupt or discontinue LYMPHIR based on severity. Institute appropriate medical management.
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Hepatotoxicity
LYMPHIR can cause hepatotoxicity. In the pooled safety population, elevated ALT occurred in 70% of patients, with Grade 3 ALT occurring in 22%; elevated AST occurred in 64% of patients, with Grade 3 AST elevation occurring in 9%. For Grade 3 events, median time to onset was 8 days (range: 1 to 15 days); median time to resolution was 15 days (range: 7 to 50 days); all cases of Grade 3 ALT or AST elevations resolved. Elevated total bilirubin occurred in 5% of patients, with Grade 3 occurring in 0.9%.
Monitor liver enzymes and bilirubin at baseline and during treatment as clinically indicated. Withhold, reduce dose, or permanently discontinue LYMPHIR based on severity.
Embryo-Fetal Toxicity
Based on its mechanism of action, LYMPHIR can cause fetal harm when administered to a pregnant woman. Verify the pregnancy status of females of reproductive potential prior to the initiation of LYMPHIR. Advise pregnant women of the potential risk to the fetus. Advise females of reproductive potential to use effective contraception during treatment and for 7 days following the last dose of LYMPHIR.
ADVERSE REACTIONS
The most common adverse reactions (≥20%), including laboratory abnormalities, are increased transaminases, albumin decreased, nausea, edema, hemoglobin decreased, fatigue, musculoskeletal pain, rash, chills, constipation, pyrexia, and capillary leak syndrome.
USE IN SPECIFIC POPULATIONS
Pregnancy
Risk Summary
Based on its mechanism of action, LYMPHIR can cause fetal harm when administered to a pregnant woman. There are no available data on the use of LYMPHIR in pregnant women to evaluate for a drug-associated risk. No animal reproductive and developmental toxicity studies have been conducted with denileukin diftitox.
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Denileukin diftitox-cxdl causes depletion of regulatory T lymphocytes (Treg), immune activation, and capillary leak syndrome, compromising pregnancy maintenance. Advise pregnant women of the potential risk to a fetus.
In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies are 2-4% and 15-20%, respectively.
Lactation
Risk Summary
No data are available regarding the presence of denileukin diftitox-cxdl in human milk, the effects on the breastfed child, or on milk production. Because of the potential for serious adverse reactions in breastfed children, advise women not to breastfeed during treatment with LYMPHIR and for 7 days after the last dose.
Females and Males of Reproductive Potential
Based on its mechanism of action, LYMPHIR can cause fetal harm when administered to a pregnant woman.
Pregnancy Testing
Verify the pregnancy status of females of reproductive potential prior to initiating LYMPHIR.
Contraception
Females
Advise females of reproductive potential to use effective contraception during treatment with LYMPHIR and for 7 days after the last dose.
Infertility
Males
Based on findings in rats, male fertility may be compromised by treatment with LYMPHIR. The reversibility of the effect on fertility is unknown.
Pediatric Use
Safety and effectiveness of LYMPHIR in pediatric patients have not been established.
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Geriatric Use
Of the 69 patients with Stage I-III r/r CTCL who received LYMPHIR, 34 patients (49%) were 65 years of age and older and 10 patients (14%) were 75 years of age and older. Clinical studies of LYMPHIR did not include sufficient numbers of patients 65 years of age and older to determine whether they respond differently from younger adult patients.
You may report side effects to the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. You may also report side effects to Citius Oncology at 1-844-459-6744.
Please read Important Safety Information and full Prescribing Information, including Boxed WARNING, for LYMPHIR.
Investor Contact:
Ilanit Allen
ir@citiuspharma.com
908-967-6677 x113
Media Contact:
STiR-communications
Greg Salsburg
Greg@STiR-communications.com
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FAQ
What did Citius Oncology (CTOR) announce about its Phase 1 LYMPHIR trial?
Citius Oncology announced positive topline results from an investigator-initiated Phase 1 trial of LYMPHIR plus pembrolizumab in relapsed or refractory gynecologic cancers, reporting encouraging safety findings and signs of anti-tumor activity in a heavily pretreated patient population.
What efficacy results were reported for LYMPHIR plus pembrolizumab in the CTOR study?
The Phase 1 trial showed a 24% objective response rate and a 48% clinical benefit rate among 21 evaluable patients. Clinical benefit included complete or partial responses and stable disease lasting at least six months, indicating a meaningful disease control signal in this difficult setting.
What safety profile was observed in Citius Oncology’s Phase 1 gynecologic cancer trial?
In 25 evaluable patients, investigators reported no unexpected safety signals and no serious immune-related adverse events at any LYMPHIR dose level combined with pembrolizumab. This suggests the combination was generally manageable in a heavily pretreated population with limited treatment options.
How might the LYMPHIR and pembrolizumab data affect future studies for CTOR?
The Phase 1 study was designed to identify a recommended LYMPHIR dose for Phase 2 use with pembrolizumab. Investigators indicated that the safety profile and observed efficacy signal support further exploration of the combination in larger, later-stage trials to better define outcomes.
When will more detailed LYMPHIR Phase 1 data from Citius Oncology be presented?
Citius Oncology stated that full safety and clinical efficacy results from the investigator-initiated Phase 1 trial are expected to be presented at an international cancer conference later in 2026, providing a more comprehensive view of response durability and tolerability.
What unmet need is Citius Oncology targeting with LYMPHIR in gynecologic cancers?
The company highlighted that recurrent or refractory ovarian and endometrial cancers have poor prognoses and limited effective treatments. Responses to existing immunotherapies are often modest, so LYMPHIR’s T-regulatory cell depletion mechanism aims to enhance anti-tumor immunity in these challenging tumors.
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