GRACE: A Phase 1/2a Study of VTRU200 in Relapsed/Refractory AML, High-risk MDS, DLBCL Post CART Failure and Advanced Solid Tumors

Relapsed or refractory (R/R) acute myeloid leukemia (AML), higher-risk myelodysplastic syndromes (HR-MDS), and diffuse large B-cell lymphoma (DLBCL) after chimeric antigen receptor (CAR) T-cell therapy remain associated with poor clinical outcomes despite recent therapeutic advances. Although targeted therapies and immunotherapies have improved outcomes for some patients, treatment failure frequently occurs because of disease heterogeneity, antigen loss, immune escape, and treatment resistance. Therefore, novel therapeutic approaches capable of recognizing shared cancer-associated features across genetically diverse tumors are needed.

VTRU200 is a first-in-class, investigational trispecific T-cell engager (TCE) designed to redirect endogenous T cells toward malignant cells through simultaneous binding of CD3 on T cells and two stress-associated tumor surface markers: aberrant high-mannose glycans and phosphatidylserine (PS). These glycan and lipid structures are enriched on many malignant cells and cells within the tumor microenvironment as a consequence of altered glycosylation, metabolic stress, oxidative stress, endoplasmic reticulum stress, impaired membrane asymmetry, rapid proliferation, and resistance to therapy. In contrast, these targets are minimally exposed on most normal healthy tissues, providing the rationale for selective tumor targeting.

Preclinical studies demonstrated that VTRU200 binds tumor cells expressing these stress-associated surface markers and mediates potent T-cell activation and cytotoxicity across multiple AML models. In nonclinical studies, VTRU200 exhibited antitumor activity in vitro and in vivo, demonstrated minimal cytokine release relative to conventional CD3-engaging therapies, showed no detectable binding to normal human peripheral blood leukocytes or hematopoietic stem and progenitor cells, and did not bind an FDA-recommended panel of normal human or cynomolgus monkey tissues. Repeat-dose animal studies demonstrated a favorable therapeutic window supporting clinical evaluation.

This is a first-in-human, multicenter, open-label Phase 1/2a study evaluating the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity, and preliminary antitumor activity of VTRU200 administered by intravenous infusion.

The Phase 1 dose-escalation portion will determine the maximum tolerated dose (MTD), if reached, and identify the recommended Phase 2 dose (RP2D). Dose escalation will begin with an accelerated titration design using sentinel participants at the lowest dose levels, followed by a Bayesian Optimal Interval (BOIN) design after evidence of acceptable safety. Escalation decisions will be based on predefined safety criteria and review by the Safety Review Committee.

Following determination of the RP2D, the Phase 2a dose-expansion portion will further characterize the safety profile and evaluate preliminary clinical activity in disease-specific cohorts. Adult participants with R/R AML and HR-MDS will constitute the primary efficacy population, with additional exploratory cohorts enrolling participants with DLBCL following CAR T-cell therapy failure. Adolescent and pediatric participants with AML may be enrolled after establishment of an acceptable safety profile and appropriate adult exposure.

Safety evaluations will include monitoring of adverse events, serious adverse events, infusion-related reactions, immune-mediated toxicities including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), clinical laboratory testing, vital signs, electrocardiograms, physical examinations, and concomitant medications.

PK assessments will characterize serum concentrations of VTRU200, while immunogenicity assessments will evaluate anti-drug antibodies (ADA). PD analyses will assess biomarkers of immune activation, cytokine responses, target engagement, and changes within peripheral blood and bone marrow, where applicable.

Preliminary antitumor activity will be evaluated using disease-specific response criteria, including the European LeukemiaNet (ELN) recommendations for AML, International Working Group (IWG) criteria for HR-MDS, and Lugano Classification criteria for DLBCL. Additional efficacy endpoints include measurable residual disease (MRD), duration of response, progression-free survival, overall survival, and other clinically relevant measures of disease control.

This study is designed primarily to establish the safety profile, appropriate dose, and biologic activity of VTRU200 while providing an initial assessment of its clinical activity in patients with relapsed or refractory hematologic malignancies for whom effective treatment options remain limited.

Inclusion criteria

• 1. Adults (≥18 years) with

I. Pathologically confirmed acute myeloid leukemia (AML) according to WHO 2022 criteria. Relapsed or refractory AML, defined as either:

• Refractory AML: Failure to achieve CR, CRh, or CRi after at least 2 courses of intensive induction therapy.
• Relapsed AML: Recurrence after prior CR, CRh, or CRi, documented by one or more of the following: Bone marrow blasts >5% by morphologic assessment; persistent reappearance of blasts in peripheral blood by morphologic assessment II. HR-MDS: Pathologically confirmed myelodysplastic syndrome (MDS) according to WHO 2022 criteria, with high-risk disease defined as IPSS-R high-risk or very high-risk (score >4.5). Ineligible for allogeneic hematopoietic stem cell transplantation.

III. DLBCL post-CAR T: histologically confirmed DLBCL per WHO 2022 criteria and relapsed or refractory disease after prior CART therapy. Qualifying post-CAR T treatment failure must be documented at least 1 month after CAR T infusion and include no metabolic response, first metabolic progressive disease, or first relapse after prior response. Prior CART infusion must have occurred at least 1 month before screening. Participants must not be in partial metabolic response or complete metabolic response at screening and must have measurable disease on PET/CT (preferred) or CT/MRI, defined as at least 1 nodal lesion >1.5 cm or at least 1 extranodal lesion >1.0 cm; if PET is used, lesions must be FDG-avid and consistent with active lymphoma IV. Advanced solid tumors 2. Children (6 months-11 years) and adolescents (12-17 years) with R/R-AML.

• Children and adolescent refractory AML: Bone marrow contains 1% blasts by multiparametic flow cytometry (MFC) at the end of 2 cycles of induction therapy
• Children and adolescent relapsed AML: A single bone marrow sample showing 5% leukemic blasts by MFC, fluorescence in situ hybridization (FISH) testing or other molecular method, or a single bone marrow sample with at least two tests showing 1% blasts such as by MFC, karyotypic abnormality with at least one metaphase similar or identical to diagnosis, FISH abnormality identical to one present at diagnosis (above level of sensitivity of specific FISH probe) or polymerase chain reaction (PCR) or next generation sequencing (NGS)-based demonstration of leukemogenic lesion (e.g., fusion, mutation) identical to diagnosis and is quantifiably 1% 3. Eastern Cooperative Oncology Group (ECOG) performance status 0-2 or Karnofsky Performance Score (KPS) ≥50% 4. Adequate organ function: I. Hepatic: Serum AST/ALT ≤2.5×ULN and total bilirubin ≤1.5×ULN (≤3×ULN if Gilbert's syndrome) II. Renal: Serum creatinine ≤1.5×ULN; Calculated CrCl: ≥40 mL/min (Cockcroft-Gault [adults]; Schwartz formula [adolescents]; apply if serum creatinine is borderline) III. Cardiac: ejection fraction ≥ 50% and no evidence of pericardial effusion as determined by ECHO IV. Hematologic: WBC count must be ≤20 × 10⁹/L prior to the first dose of study treatment and before each dose in Cycle 1; patients with WBC >20 × 10⁹/L may receive cytoreduction with hydroxyurea (up to 4 g/day) and/or leukapheresis per protocol to achieve this threshold, with hydroxyurea held ≥12-24 hours before each study treatment dose 5. Females of childbearing potential must have a negative serum or urine pregnancy test 6. Adults: written informed consent. Adolescents: written patient assent plus parental/guardian informed consent.

• Prior treatment with an investigational agent is permitted provided that at least 5 half-lives have elapsed and all treatment-related toxicities have resolved to Grade ≤1 (except alopecia). Prior T-cell engaging, checkpoint inhibitor, or cellular therapies require a minimum washout of 8 weeks.

Exclusion criteria

• 1. Active central nervous system (CNS) disease requiring treatment. 2. Uncontrolled or clinically significant baseline neurologic disorder (e.g., uncontrolled seizures or severe cognitive impairment/delirium), significant psychiatric illness or active substance abuse.

• Uncontrolled infections including persistent bacteremia/fungemia despite appropriate therapy, progressive invasive fungal infection, or uncontrolled viral infection with end-organ disease. Active tuberculosis.

• Concurrent malignancy requiring active systemic therapy. 5. Cytotoxic chemotherapy within 14 days prior to first dose. Targeted anti-leukemic therapy within 7-14 days prior to first dose. Radiotherapy within 14 days prior to first dose (except limited-field palliative radiotherapy). Prior CD3-engaging therapy.

• T-cell depleting therapy (ATG, alemtuzumab, or equivalent) within 6 months prior to enrollment 7. Severe uncontrolled cardiovascular disease (e.g., NYHA class III/IV heart failure, unstable angina or MI within 6 months, uncontrolled arrhythmia). Severe uncontrolled pulmonary disease (e.g., requiring high-flow oxygen or ventilatory support).

• Systemic corticosteroids >10 mg/day prednisone equivalent within 7 days prior to first dose.

• Active autoimmune disease requiring systemic immunosuppression within the past 12 months.

• Prior allogeneic transplant within 3 months or active graft-versus-host disease (GVHD).

• Primary immunodeficiency (congenital immunodeficiency disorder requiring ongoing medical management).

• Known HIV infection. Hepatitis B: HBsAg positive (chronic HBV infection). Hepatitis C: anti-HCV positive (HCV exposure).

• Pregnant or breastfeeding 14. Known congenital or acquired bleeding disorder, including hemophilia A/B or von Willebrand disease, or other clinically significant coagulopathy 15. History of severe allergic reaction to immunotherapy