On December 8, 2025 The Menarini Group ("Menarini"), a leading international pharmaceutical and diagnostics company, and Stemline Therapeutics, Inc. ("Stemline"), a wholly-owned subsidiary of the Menarini Group, focused on bringing transformational oncology treatments to cancer patients, reported it will present updated meaningful median progression-free survival (mPFS) efficacy results from two combination regimens of the Phase 2 ELEVATE study in patients with estrogen receptor-positive (ER+), HER2-negative (HER2-) locally advanced or metastatic breast cancer (mBC). The ELEVATE study was designed to evaluate the safety and efficacy of oral-oral combination treatment options to overcome different resistance mechanisms observed in ER+/HER2- mBC with the goal of improving patient outcomes. These data will be presented at the 2025 San Antonio Breast Cancer Symposium (SABCS), December 9-12.

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"The encouraging progression-free survival data increase our confidence in the role elacestrant could play as an endocrine therapy backbone in the combination setting," said Virginia Kaklamani, MD, DSc, Professor of Medicine in the Division of Hematology/Oncology at UT Health San Antonio, and Leader of the Breast Cancer Program at UT Health San Antonio MD Anderson Cancer Center. "The safety profile of elacestrant in combination with everolimus or abemaciclib is consistent with the known safety profiles of each drug. No new safety signals have been observed."

The ELEVATE data to be presented at SABCS demonstrate that elacestrant in combination with everolimus or with abemaciclib shows a consistent PFS benefit, irrespective of ESR1 mutation status in patients with ER+/HER2- mBC, who experience disease progression on endocrine therapy (ET), with or without prior exposure to CDK4/6 inhibitors. These updated results also show that the safety of the combinations are consistent with the known safety profiles of each targeted therapy plus standard of care endocrine therapy.

Phase 2 mPFS in months (95% CI) in all patients and subgroups

Patient Population

Elacestrant 345 mg QD

+ Everolimus 7.5mg QD

(n=50)

Elacestrant 345 mg QD

+ Abemaciclib 150 mg BID

(n=60)

All patients

8.3 [4.0 – 10.2]

14.3 [7.3-16.6]

Visceral disease

7.7 [3.8 – 9.4]

14.3 [7.4-16.6]

No prior fulvestrant

8.3 [4.2 – 12.9]

14.8 [8.7-NR]

No primary endocrine resistance

8.3 [4.0-12.9]

14.3 [7.3-16.6]

ESR1mut

8.7 [3.5 – 12.9]

*

ESR1wt

9.0 [4.2 – 12.7]

*

PIK3CAmut

8.3 [3.6 – 10.2]

*

PIK3CAwt

9.6 [5.6 – NR]

*

*Maturity not reached for PFS (95% CI) for genomic subgroups (ESR1 / PIK3CA) in the elacestrant + abemaciclib cohort.

"The extensive evidence for elacestrant spans the monotherapy setting in our pivotal EMERALD study, now backed by two recent real-world data publications[1], [2], and in its growing potential in combination regimens, as highlighted by the data presented at SABCS," said Elcin Barker Ergun, CEO of the Menarini Group. "We remain deeply committed to fully exploring elacestrant’s potential benefit across multiple ongoing trials in both early stage and metastatic breast cancer."

Additionally, other elacestrant updates will be presented at SABCS, investigating its potential across the spectrum of breast cancer:

Presentation Title: Elacestrant in combination with everolimus or abemaciclib in patients with ER+/HER2-locally advanced or metastatic breast cancer (mBC): phase 2 results from ELEVATE, an open-label, umbrella study
Abstract Number: 1255
Presentation Date & Time: Thursday, December 11, 2025, 1:00 – 2:00 PM
Location: Hemisfair1-2
Presenting Author: Hope S. Rugo

Presentation Title: Elacestrant alone or in combination with triptorelin in premenopausal women with ER+/HER2-early breast cancer: primary analysis from the phase 2 SOLTI-2104-PremiÈRe trial
Abstract Number: 1123
Presentation Date & Time: Friday, December 12, 2025, 7:30 – 7:33 AM
Location: 301 ABC
Presenting Author: Mertixell Bellet

Presentation Title: ELEGANT: Elacestrant Versus Standard Endocrine Therapy (ET) in Women and Men With Node-positive, Estrogen Receptor-positive (ER+), HER2-negative (HER2-), Early Breast Cancer (eBC) With High Risk of Recurrence in a Global, Multicenter, Randomized, Open-label Phase 3 Study.
Abstract Number: 1276
Presentation Date & Time: Thursday, December 11, 2025, 12:30 – 2:00 PM
Location: Henry B. Convention Center
Presenting Author: Aditya Bardia

Presentation Title: The ADELA study: A Double-blind, Placebo-controlled, Randomized Phase 3 Trial of Elacestrant (ELA)+ Everolimus (EVE) Versus ELA + Placebo (PBO) in ER+/HER2-Advanced Breast Cancer (aBC) Patients with ESR1-mutated Tumors Progressing on Endocrine Therapy (ET) + CDK4/6i
Abstract Number: 1141
Presentation Date & Time: Wednesday, December 10, 2025, 12:30 – 2:00 PM
Location: Henry B. Convention Center
Presenting Author: Antonio Llombart-Cussac

Presentation Title: ERADICATE: A phase Ib/II study of elacestrant plus trastuzumab deruxtecan in patients with CDK4/6 inhibitor and endocrine-resistant HR+/HER2-low or HER2-ultralow metastatic breast cancer
Abstract Number: 2119
Presentation Date & Time: Friday, December 12, 2025, 12:30 – 2:00 PM
Location: Henry B. Convention Center
Presenting Author: Sara L. Sammons

Presentation Title: Hormonal receptor (HR)-positive HER2 negative breast cancer patients treated with preoperative Elacestrant and PULSAR adaptive radiotherapy: a phase II study (HELP Trial)
Abstract Number: 1071
Presentation Date & Time: Friday, December 12, 2025, 12:30 – 2:00 PM
Location: Henry B. Convention Center
Presenting Author: Luca Visani

About The Elacestrant Clinical Development Program

Elacestrant is also being investigated in several company-sponsored clinical trials in metastatic breast cancer disease, alone or in combination with other therapies. ELEVATE (NCT05563220) is a phase 1b/2 clinical trial evaluating the safety and efficacy of elacestrant combined with alpelisib, everolimus, capivasertib, palbociclib, ribociclib or abemaciclib. ELECTRA (NCT05386108) is an open-label phase 1b/2, multicenter study evaluating elacestrant in combination with abemaciclib in patients with ER+, HER2- breast cancer. The phase 2 portion evaluates this treatment regimen in patients with brain metastases. ELCIN (NCT05596409) is a phase 2 trial evaluating the efficacy of elacestrant in patients with ER+, HER2- advanced/metastatic breast cancer who received one or two prior hormonal therapies and no prior CDK4/6 inhibitors in the metastatic setting. ADELA (NCT06382948) is a phase 3 randomized, double-blinded trial evaluating elacestrant in combination with everolimus in patients with ER+, HER2- mBC with ESR1-mut tumors. Elacestrant is also being evaluated in additional investigator-led trials, in trials conducted in collaboration with other companies, in metastatic breast cancer as well as in early disease.

About ORSERDU (elacestrant)
U.S. Indication: ORSERDU (elacestrant), 345 mg tablets, is indicated for the treatment of postmenopausal women or adult men with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, ESR1-mutated advanced or metastatic breast cancer with disease progression following at least one line of endocrine therapy.

Full prescribing information for the U.S. can be found at www.orserdu.com.

Important Safety Information
Warning and Precautions

Dyslipidemia: Hypercholesterolemia and hypertriglyceridemia occurred in patients taking ORSERDU at an incidence of 30% and 27%, respectively. The incidence of Grade 3 and 4 hypercholesterolemia and hypertriglyceridemia were 0.9% and 2.2%, respectively. Monitor lipid profile prior to starting and periodically while taking ORSERDU.

Embryo-Fetal Toxicity: Based on findings in animals and its mechanism of action, ORSERDU can cause fetal harm when administered to a pregnant woman. Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with ORSERDU and for 1 week after the last dose. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with ORSERDU and for 1 week after the final dose.

Adverse Reactions

Serious adverse reactions occurred in 12% of patients who received ORSERDU. Serious adverse reactions in >1% of patients who received ORSERDU were musculoskeletal pain (1.7%) and nausea (1.3%). Fatal adverse reactions occurred in 1.7% of patients who received ORSERDU, including cardiac arrest, septic shock, diverticulitis, and unknown cause (one patient each).
The most common adverse reactions (>10%), including laboratory abnormalities, of ORSERDU were musculoskeletal pain (41%), nausea (35%), increased cholesterol (30%), increased AST (29%), increased triglycerides (27%), fatigue (26%), decreased hemoglobin (26%), vomiting (19%), increased ALT (17%), decreased sodium (16%), increased creatinine (16%), decreased appetite(15%), diarrhea(13%), headache (12%), constipation (12%), abdominal pain (11%), hot flush (11%), and dyspepsia (10%).

Drug interactions

Concomitant use with CYP3A4 Inducers and/or inhibitors: Avoid concomitant use of strong or moderate CYP3A4 inhibitors with ORSERDU. Avoid concomitant use of strong or moderate CYP3A4 inducers with ORSERDU.

Use in specific populations

Lactation: Advise lactating women to not breastfeed during treatment with ORSERDU and for 1 week after the last dose.
Hepatic Impairment: Avoid use of ORSERDU in patients with severe hepatic impairment (Child-Pugh C). Reduce the dose of ORSERDU in patients with moderate hepatic impairment (Child-Pugh B).
The safety and effectiveness of ORSERDU in pediatric patients have not been established.

To report SUSPECTED ADVERSE REACTIONS, contact Stemline Therapeutics, Inc. at 1-877-332-7961 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

(Press release, Menarini, DEC 8, 2025, View Source;metastatic-breast-cancer-mbc-at-the-2025-san-antonio-breast-cancer-symposium-302635656.html [SID1234661281])

On December 8, 2025 Oncoinvent, a clinical stage, radiopharmaceutical company developing innovative treatments for solid cancers, reported the publication of 12-month data from its Phase 1 study of patients with platinum-sensitive recurrent ovarian cancer and peritoneal carcinomatosis. The results from the first patients have been published in the respected peer-reviewed journal Gynecologic Oncology, under the title: "First experience with intraperitoneal 224Ra-labeled microparticles after cytoreductive surgery in patients with peritoneal recurrence of platinum-sensitive epithelial ovarian cancer."

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"We are proud to announce that our article has been published in Gynecologic Oncology. This recognition underscores the importance of our research and validates our ongoing efforts. As our phase 2 study progresses in patients with peritoneal metastasis from ovarian cancer, we remain fully committed to advancing new treatment options to address this urgent medical need," said Kari Myren, Chief Medical Officer at Oncoinvent.

The primary objectives of the phase 1 study were to evaluate the safety and tolerability of the alpha emitting therapy using 224Ra-labeled microparticles (Radspherin) and to determine the recommended dose for subsequent clinical development. Initial experiences indicate that all dose levels were well tolerated, no dose limiting toxicity was observed during dose escalation and the highest dose of 7 MBq was selected as the recommended dose for the expansion phase. Alongside the now published 12-month data, Oncoinvent has also released topline 24-month follow-up data for the phase 1 study in ovarian cancer patients.

A randomized controlled phase 2 study is ongoing to evaluate the efficacy and safety of Radspherin in patients with peritoneal metastasis from ovarian cancer. The primary aim is to compare progression-free survival (PFS) between two groups: those who receive Radspherin following complete surgical resection after pre-operative chemotherapy, and those treated with pre-operative chemotherapy and surgery alone. Further details can be found at clinicaltrials.gov.

(Press release, Oncoinvent, DEC 8, 2025, https://www.oncoinvent.com/press-release/oncoinvent-announces-publication-of-phase-1-study-results-for-radspherin-in-ovarian-cancer-in-gynecologic-oncology/ [SID1234661280])

On December 8, 2025 Immutep Limited (ASX: IMM; NASDAQ: IMMP) ("Immutep" or "the Company"), a late-stage immunotherapy company targeting cancer and autoimmune diseases and Dr. Reddy’s Laboratories Ltd., (BSE: 500124 | NSE: DRREDDY | NYSE: RDY | NSEIFSC: DRREDDY, and along with its subsidiaries, hereafter referred to as "Dr. Reddy’s"), reported that their respective wholly-owned subsidiaries, Immutep SAS and Dr. Reddy’s Laboratories SA, have entered into a strategic collaboration and exclusive licensing agreement for the development and commercialisation of Eftilagimod Alfa (efti) in all countries outside North America, Europe, Japan, and Greater China.

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Efti is Immutep’s first-in-class novel immunotherapy that directly activates the immune system to fight cancer, which is under evaluation in TACTI-004 (KEYNOTE-F91), a registrational Phase III trial for the first-line therapy of advanced or metastatic non-small cell lung cancer. Efti is also being investigated in other indications including head & neck cancer, breast cancer, and soft tissue sarcoma.

The terms of the licensing agreement provide Immutep with significant milestones and preserves its ability to capture material future upside in the licensed markets as efti advances commercially. Further, Immutep holds the global manufacturing rights to the product across all markets and will supply the product to Dr. Reddy’s in the licensed markets, while Immutep retains all rights to the product in the key pharmaceutical markets, including North America, Europe, and Japan.

Additionally, as per the agreement, Immutep will receive from Dr. Reddy’s an upfront payment of USD 20 million (~AUD 30.2 million). It is also eligible to receive potential regulatory development and commercial milestone payments of up to USD 349.5 million (~AUD 528.4 million), plus double-digit royalties on commercial sales in these markets.

"This collaboration marks our continuous efforts to deliver first-in-class and innovative therapies for cancer treatment. Efti is a novel immunotherapy with the potential to set a new standard of care in combination with pembrolizumab (Keytruda) and chemotherapy as first-line therapy for non-small cell lung cancer. Its broad potential extends to other major cancers across multiple stages of disease. Through this agreement, we look forward to leveraging our expertise and strong market access to advance the development and commercialization of this promising cancer therapy in the licensed markets," stated M.V. Ramana, CEO – Branded Markets (India & Emerging Markets), Dr. Reddy’s.

"This agreement with Dr. Reddy’s marks a significant milestone for Immutep and further validates the potential of efti. Dr. Reddy’s proven capabilities and reach in the licensed markets make them an ideal partner to maximise the impact of our innovation and serve a large number of patients across the globe. Additionally, this partnership allows us to capture significant value for efti in the licensed markets, while retaining full rights in key markets such as North America, Europe, and Japan, and ensures we remain very well-positioned for future value creation," said Marc Voigt, CEO of Immutep.

About Eftilagimod Alfa (Efti):

Efti is a first-in-class soluble LAG-3 protein and MHC Class II agonist delivered subcutaneously that uniquely activates antigen-presenting cells or APCs (e.g., dendritic cells, monocytes) via major histocompatibility complex (MHC) class II ligands. As an MHC Class II agonist, its activation of APCs engages the adaptive and innate immune system to initiate a broad anti-cancer immune response. This includes priming and activating cytotoxic T cells as well as generating important co-stimulatory signals & cytokines that further boost the immune system’s ability to combat cancer.

Efti is under evaluation for a variety of solid tumours including non-small cell lung cancer (NSCLC) in a pivotal Phase III trial called TACTI-004 (KEYNOTE-F91), as well as head and neck squamous cell carcinoma (HNSCC), soft tissue sarcoma, and breast cancer. Its favourable safety profile enables various combinations like with anti-PD-[L]1 immunotherapy, radiotherapy, and/or chemotherapy. This has been demonstrated across early-stage trials in NSCLC and HNSCC, which have laid the foundation for the larger randomized clinical trial in NSCLC. Efti has received Fast Track designation in first line HNSCC and in first line NSCLC from the United States Food and Drug Administration (FDA).

(Press release, Immutep, DEC 8, 2025, View Source [SID1234661279])

On December 8, 2025 Autolus Therapeutics plc (Nasdaq: AUTL), an early commercial-stage biopharmaceutical company developing, manufacturing and delivering next-generation programmed T cell therapies, reported presentation of preliminary data from the ongoing Phase 1 CARLYSLE trial in patients with severe refractory systemic lupus erythematosus (srSLE) in an oral presentation at the American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting.

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Dr. Matthias Will, Chief Development Officer of Autolus, said: "Patients with srSLE have limited remaining treatment options and represent a difficult to treat population with a critical unmet need. Data reported from the CARLYSLE trial show an encouraging high rate of DORIS responses and a deep reset in the B cell compartment induced by obe-cel, suggesting the possibility for an immune reset. Based on this positive initial experience with obe-cel in the CARLSYLE trial we have initiated the LUMINA trial, a Phase 2 trial in lupus nephritis with registrational intent."

Abstract 302
Title: Obecabtagene autoleucel (obe-cel), a CD19-targeting chimeric antigen receptor (CAR) T-cell therapy, in patients with severe, refractory systemic lupus erythematosus (SLE) in the Phase I CARLYSLE study: initial safety, preliminary efficacy, pharmacokinetics, and biomarker results
Session Name: Cellular Immunotherapies: Early Phase Clinical Trials and Toxicities: Emerging CAR-T Cell Therapies for Acute Leukemias and Autoimmune Diseases
Session Date and Time: December 8, 2025; 11:30 – 11:45am ET
Session Room: Orange County Convention Center; Valencia Room W415D
Publication Number: 815
Presenting Author: Claire Roddie, MD, PhD, FRCPath, Associate Professor Haematology and Honorary Consultant Haematologist, Cancer Institute, University College London (UCL)

Summary: Updated Phase 1 data with longer follow-up, and data in patients who received both 50×106 (50M) and 100×106 (100M) CAR T-cells were presented. Nine adult patients were infused with obe-cel, including six at the 50M dose and three at the 100M dose.

Obe-cel was well tolerated in all patients. No dose limiting toxicities (DLTs) or cases of immune effector cell-associated neurotoxicity syndrome (ICANS) were observed at the 50M dose. Grade one cytokine release syndrome (CRS) was observed in three patients at the 50M dose and three patients at the 100M dose. Hypertension was observed in five patients at the 50M dose, with three of those patients having pre-existing history of hypertension. A case of transient Grade three liver toxicity was observed in one patient of the 100M cohort.

At the 50M dose, three patients (50%) achieved CRR and five patients (83%) achieved DORIS with a median onset of 5.1 months (range: 4.9–8.9), without evidence of new disease activity at a median of 12 months of follow up (range: 8.5–16.3). All non-renal manifestations of the disease resolved by month four. Urinary protein creatinine (UPC) ratio levels decreased over time, demonstrating significant decline or absence of disease activity. Data show high peak expansion and deep B cell aplasia consistent with known obe-cel characteristics in oncology indications. Peak expansion was reached at a median of 10 days (range: 9–13). The median time to loss of CAR T-cell persistence based on Kaplan-Meier analysis was 3.0 months. The B-cell reconstitution profiles suggest that obe-cel may induce a reset of pathologic autoimmunity.

Emerging data in the 100M cohort is consistent with the 50M adult cohort, and evaluation is ongoing.

Data support progressing obe-cel as a treatment for srSLE and 50M has been selected as the recommended Phase 2 dose. Autolus has aligned with U.S. Food and Drug Administration (FDA) on a Phase 2 trial design in LN and potential registrational path to approval. The LUMINA trial is now enrolling.

Dr. Christian Itin, Autolus Chief Executive Officer, said: "Obe-cel’s safety profile is based on a robust database spanning several clinical trials in B-ALL and B-NHL indications. Data presented today now also show the ability to induce deep depletion of B-cell lineages in patients with srSLE. Obe-cel successfully underwent the regulatory approval process with the FDA, EMA and MHRA in adult r/r B-ALL and launched commercially in the US and UK in 2025. Building on this strong foundation of clinical data, and demonstrated commercial and manufacturing capabilities, we believe Autolus is well positioned for a successful and efficient path into the autoimmune setting."

(Press release, Autolus, DEC 8, 2025, View Source [SID1234661278])

On December 8, 2025 Autolus Therapeutics plc (Nasdaq: AUTL), an early commercial-stage biopharmaceutical company developing, manufacturing and delivering next-generation programmed T cell therapies, reported presentation of preliminary data from the CATULUS Phase 1 trial of obe-cel in pediatric relapsed or refractory (r/r) B-ALL patients, as well as further insights from the registrational FELIX study in adult r/r B-ALL, at the American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting.

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Dr. Matthias Will, Chief Development Officer of Autolus, said: "Pediatric patients with r/r B-ALL have a poor prognosis, particularly those who relapse early. We were pleased to share the first data from the Phase 1 CATULUS trial showing obe-cel can produce high remission rates in this pediatric patient population, including in patients with high-risk relapse and patients with primary CNS relapse. Consistent with our experience in the adult population, data show low rates of severe CRS and ICANS. We are now advancing into the Phase 2 portion of the study in line with our commitment to address the significant unmet need for new treatment options for pediatric patients with r/r ALL."

Dr. Will continued, "Insights from post-hoc analyses from our FELIX pivotal trial in r/r adult B-ALL explored various factors that may help to predict long-term patient outcomes. Specifically, investigators showed that detection of obe-cel in the blood three months post-treatment may be a predictor for long-term outcomes. They also identified characteristics of the product’s cell phenotype as additional factors for treatment outcomes."

He concluded, "In addition to Autolus’ presentations, we were highly encouraged by data from the real-world experience of the ROCCA consortium evaluating CAR T therapy for r/r adult ALL patients. These real world data mirror obe-cel’s safety profile observed in the pivotal FELIX trial with low single digits rates of CRS and ICANS as one of the differentiating characteristics of the therapy."

Abstract 740 – Poster presentation
Title: Treatment of pediatric patients (pts) with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) with obecabtagene autoleucel (obe-cel), a CD19-directed chimeric antigen receptor (CAR) T-cell therapy: preliminary findings from the Phase Ib/II CATULUS trial
Session Name: Acute Lymphoblastic Leukemias: Therapies Excluding Allogeneic Transplantation: Poster II
Session Date and Time: December 7, 2025; 6:00 – 8:00pm ET
Session Room: Orange County Convention Center; West Halls B3-B4
Publication Number: 3337
Presenting Author: Sara Ghorashian, Consultant Haematologist at Great Ormand Street Hospital for Children (GOSH) and Honorary Associate Professor at UCL

Summary: CATULUS is a single-arm, open-label, multi-center study enrolling high-risk patients under age 18 with r/r B-ALL that is primary refractory, in high-risk first relapse, or in second or later relapse. The safety profile of obe-cel in pediatric patients was consistent with that previously reported in adults, with low rates of high-grade CRS and ICANS (both 8.7%). The ORR was high at 95.5% (n=21), with 90.9% (n=20) achieving complete response (CR). Twenty patients were in ongoing remission at data cut-off with a median follow-up of 8.8 months. These preliminary findings support further exploration of obe-cel in pediatric R/R B-ALL and planning for the Phase II expansion is underway.

Abstract 4060 – Poster presentation
Title: Chimeric antigen receptor (CAR) T-cell persistence at Month 3 predicts clinical outcomes in adult patients with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) treated with obecabtagene autoleucel (obe-cel)
Session Name: Acute Lymphoblastic Leukemias: Therapies Excluding Allogeneic Transplantation: Poster III
Session Date and Time: December 8, 2025; 6:00 – 8:00pm ET
Session Room: Orange County Convention Center; West Halls B3-B4
Publication Number: 5118
Presenting Author: Claire Roddie, MD, PhD, FRCPath, Associate Professor Haematology and Honorary Consultant Haematologist, Cancer Institute, University College London (UCL)

Summary: Of 99 patients who achieved remission (CR/CRi) in the FELIX study, 79 (79.8%) had ongoing remission at month three following obe-cel infusion and comprised the subgroup of interest for the analyses. At month three post infusion, 60/79 patients (75.9%) had ongoing CAR T-cell persistence, while 19/79 patients (24.1%) had loss of persistence. In patients who remained in remission beyond month three, including those with deep MRD-negative remission and no post obe-cel SCT, ongoing CAR T-cell persistence at month three, measured by droplet digital PCR (ddPCR), was associated with longer event-free survival (EFS) and overall survival (OS) compared with loss of persistence. These results suggest that persistence status at month three may be a marker for predicting long-term outcomes following obe-cel treatment in patients with r/r B-ALL.

Abstract 4031 – Poster presentation
Title: Evaluation of commercially available chimeric antigen receptor (CAR) detection reagents for monitoring of CAR T-cell (CAR T) expansion and persistence in patients (pts) treated with obecabtagene autoleucel (obe-cel)
Session Name: Cellular Immunotherapies: Early Phase Clinical Trials and Toxicities: Poster I
Session Date and Time: December 6, 2025; 5:30 – 7:30pm ET
Session Room: Orange County Convention Center; West Halls B3-B4
Publication Number: 2367
Presenting Author: Rehan Hussain, Translational Medicine Senior Scientist

Summary: Measuring obe-cel expansion and persistence using flow cytometry (FC) is feasible with commercially available antibodies that directly target regions of the CAR construct, such as the G4S linker. These reagents show high correlation with anti-idiotype antibodies and provide a reliable method for tracking CAR expression in patients. Use of the G4S binder enabled tracking of CAR T expansion kinetics and phenotypic profiles in patients with different disease burdens. Reagents based on the CD19 protein, commonly used in other CAR T therapies, are unsuitable for obe-cel due to the unique features of the CAT19 binder, which limits effective detection.

Abstract 4429 – Oral presentation
Title: Impact of chimeric antigen receptor (CAR) product cell phenotypes on clinical outcomes following treatment with obecabtagene autoleucel (obe-cel)
Session Name: Acute Lymphoblastic Leukemias: Biomarkers, Molecular Markers, and Measurable Residual Disease in Diagnosis and Prognosis: Prognostic Genetic and Therapeutic Response Factors in Adult and Pediatric B-ALL
Session Date and Time: December 6, 2025; 10:00 – 10:15am ET
Session Room: Orange County Convention Center; W224CDGH
Publication Number: 33
Presenting Author: Benjamin Simpson, Ph.D., Bioinformatics & Data Management Principal Scientist, Autolus Therapeutics

Summary: Clinical data show the potential for obe-cel to produce long-term outcomes. This analysis details certain product features potentially affecting clinical outcomes, including how drug product phenotypes correlate with treatment outcomes following infusion with obe-cel. A higher percentage of central memory cells (Tcm) in the drug product samples was an independent predictor of positive clinical outcomes, including overall survival (OS), following obe-cel infusion. While the T-cell phenotype composition in the leukapheresis product (LP) was weakly correlated with that in the drug product, CD25+ HLADR+ CD4+ cells in the LP independently predicted less favorable clinical outcomes. However, other factors (e.g. tumor characteristics) are also likely to affect outcomes; therefore, further investigations are needed to better understand and predict favorable clinical outcomes, and to potentially guide studies of additional cell manipulations during CAR T-cell manufacturing.

(Press release, Autolus, DEC 8, 2025, View Source [SID1234661277])