お知らせ • Mar 11
Citius Oncology, Inc. Announces Positive Topline Results from Investigator-Initiated Phase 1 Study of LYMPHIR™ in Combination with Pembrolizumab in Relapsed or Refractory Gynecologic Cancers
Citius Oncology, Inc. 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. 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. 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. 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 2026, 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 year. 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. 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. 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. 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. 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 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. 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. 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. 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 initiating LYMPHIR. Advise females of reproductive potential to use effective contraception during treatment with LYMPHIR and for 7 days after the last dose. Based on findings in rats, male fertility may be compromised by treatment with LYMPHIR. The reversibility of the effect on fertility is unknown. Safety and effectiveness of LYMPHIR in pediatric patients have not been established. 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.