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Pepinemab in Treating Younger Patients With Recurrent, Relapsed, or Refractory Solid Tumors

A Phase 1/2 Study of VX15/2503 in Children, Adolescents, or Young Adults With Recurrent or Relapsed Solid Tumors

Status
Completed
Phases
Phase 1Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT03320330
Enrollment
26
Registered
2017-10-25
Start date
2018-01-31
Completion date
2024-06-30
Last updated
2024-07-15

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Recurrent Malignant Solid Neoplasm, Recurrent Osteosarcoma, Refractory Malignant Solid Neoplasm, Refractory Osteosarcoma

Brief summary

This phase I/II trial studies the side effects and best dose of pepinemab and to see how well it works in treating younger patients with solid tumors that have come back after treatment, or do not respond to treatment. Immunotherapy with monoclonal antibodies, such as pepinemab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread.

Detailed description

PRIMARY OBJECTIVES: I. To estimate the maximum tolerated dose (MTD) and/or recommended phase 2 dose of pepinemab (VX15/2503) administered as an intravenous infusion every 14 days to children with recurrent or refractory solid tumors. (Part A) II. To define and describe the toxicities of VX15/2503 administered on this schedule. (Parts A-B) III. To characterize the pharmacokinetics of VX15/2503 in children with recurrent or refractory cancer. (Parts A-B) IV. To preliminarily define the antitumor activity of VX15/2503 for the treatment of relapsed or refractory osteosarcoma. (Part B) V. To determine if VX15/2503 either improves the disease control rate at 4 months in patients with recurrent measurable osteosarcoma or produces an objective response rate in patients with relapsed or refractory osteosarcoma. (Part B) SECONDARY OBJECTIVES: I. To assess the pharmacodynamics of VX15/2503 through VX15/2503 saturation of T-lymphocytes. II. To assess the immunogenicity of VX15/2503 in pediatric patients with recurrent or refractory cancer. EXPLORATORY OBJECTIVES: I. To evaluate potential biomarkers of VX15/2503 sensitivity including SEMA4D, PlexinB1, and other markers of immune cell infiltration in archival tumor tissues. OUTLINE: This is a phase I, dose-escalation study followed by a phase II study. Patients receive pepinemab intravenously (IV) over 60 minutes on days 1 and 15. Treatment repeats every 28 days for 13 cycles in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up periodically.

Interventions

OTHERLaboratory Biomarker Analysis

Correlative studies

BIOLOGICALPepinemab

Given IV

OTHERPharmacological Study

Correlative studies

Sponsors

National Cancer Institute (NCI)
CollaboratorNIH
Children's Oncology Group
Lead SponsorNETWORK

Study design

Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
12 Months to 30 Years
Healthy volunteers
No

Inclusion criteria

* Part A: Patients with recurrent or refractory solid tumors are eligible, excluding central nervous system (CNS) tumors; patients must have had histologic verification of malignancy at original diagnosis or relapse * Part B: Patients with recurrent or refractory osteosarcoma are eligible; patients must have had histologic verification of malignancy at original diagnosis or relapse * Part A: Patients must have either measurable or evaluable disease * Part B: Patients must have measurable disease * Patient's current disease state must be one for which there is no known curative therapy or therapy proven to prolong survival with an acceptable quality of life * Karnofsky \>= 50% for patients \> 16 years of age and Lansky \>= 50 for patients =\< 16 years of age; patients who are unable to walk because of paralysis, but who are up in a wheelchair, will be considered ambulatory for the purpose of assessing the performance score * Patients must have fully recovered from the acute toxic effects of all prior anti-cancer therapy and must meet the following minimum duration from prior anti-cancer directed therapy prior to enrollment; if after the required timeframe, the numerical eligibility criteria are met, e.g. blood count criteria, the patient is considered to have recovered adequately * Cytotoxic chemotherapy or other anti-cancer agents known to be myelosuppressive * \>= 21 days after the last dose of cytotoxic or myelosuppressive chemotherapy (42 days if prior nitrosourea) * Anti-cancer agents not known to be myelosuppressive (e.g. not associated with reduced platelet or absolute neutrophil count \[ANC\] counts): \>= 7 days after the last dose of agent * Antibodies: \>= 21 days must have elapsed from infusion of last dose of antibody, and toxicity related to prior antibody therapy must be recovered to grade =\< 1 * Corticosteroids: If used to modify immune adverse events related to prior therapy, \>= 14 days must have elapsed since last dose of corticosteroid * Hematopoietic growth factors: \>= 14 days after the last dose of a long-acting growth factor (e.g. pegfilgrastim) or 7 days for short-acting growth factor; for agents that have known adverse events occurring beyond 7 days after administration, this period must be extended beyond the time during which adverse events are known to occur; the duration of this interval must be discussed with the study chair and the study-assigned research coordinator * Interleukins, interferons and cytokines (other than hematopoietic growth factors): \>= 21 days after the completion of interleukins, interferon or cytokines (other than hematopoietic growth factors) * Stem cell Infusions (with or without total body irradiation \[TBI\]): * Allogeneic (non-autologous) bone marrow or stem cell transplant, or any stem cell infusion including donor lymphocyte infusion (DLI) or boost infusion: \>= 84 days after infusion and no evidence of graft versus host disease (GVHD) * Autologous stem cell infusion including boost infusion: \>= 42 days * Cellular Therapy: \>= 42 days after the completion of any type of cellular therapy (e.g. modified T cells, natural killer \[NK\] cells, dendritic cells, etc.) * Radiation Therapy (XRT)/External Beam Irradiation including Protons: \>= 14 days after local XRT; \>= 150 days after TBI, craniospinal XRT or if radiation to \>= 50% of the pelvis; \>= 42 days if other substantial bone marrow (BM) radiation * Radiopharmaceutical therapy (e.g., radiolabeled antibody, 131I-MIBG): \>= 42 days after systemically administered radiopharmaceutical therapy * Patients must not have received prior exposure to VX15/2503 * Peripheral absolute neutrophil count (ANC) \>= 1000/mm\^3 * Platelet count \>= 100,000/mm\^3 (transfusion independent, defined as not receiving platelet transfusions for at least 7 days prior to enrollment) * Hemoglobin \>= 8.0 g/dL at baseline (may receive red blood cell \[RBC\] transfusions) * Patients with known bone marrow metastatic disease will be eligible for study provided they meet the blood counts above (may receive transfusions provided they are not known to be refractory to red cell or platelet transfusions); these patients will not be evaluable for hematologic toxicity; at least 5 of every cohort of 6 patients must be evaluable for hematologic toxicity for the dose-escalation part of the study; if dose-limiting hematologic toxicity is observed, all subsequent patients enrolled must be evaluable for hematologic toxicity * Creatinine clearance or radioisotope glomerular filtration rate (GFR) \>= 70 ml/min/1.73 m\^2 or * A serum creatinine based on age/gender as follows: * Age: 1 to \< 2 years; Male: 0.6 mg/dL; Female: 0.6 mg/dL * Age: 2 to \< 6 years; Male: 0.8 mg/dL; Female: 0.8 mg/dL * Age: 6 to \< 10 years; Male: 1 mg/dL; Female: 1 mg/dL * Age: 10 to \< 13 years; Male: 1.2 mg/dL; Female: 1.2 mg/dL * Age: 13 to \< 16 years; Male: 1.5 mg/dL; Female: 1.4 mg/dL * Age: \>= 16 years; Male: 1.7 mg/dL; Female: 1.4 mg/dL * Bilirubin (sum of conjugated + unconjugated) =\< 1.5 x upper limit of normal (ULN) for age * Alanine aminotransferase (ALT) serum glutamic pyruvic transaminase (SGPT) =\< 135 U/L; for the purpose of this study, the ULN for ALT is 45 U/L * Serum albumin \>= 2 g/dL * No clinical indications such as evidence of dyspnea at rest, or exercise intolerance due to pulmonary insufficiency * If clinical indications, pulse oximetry \> 94% on room air * All patients and/or their parents or legally authorized representatives must sign a written informed consent; assent, when appropriate, will be obtained according to institutional guidelines * Tissue blocks or slides must be sent; if tissue blocks or slides are unavailable, the study chair must be notified prior to enrollment

Exclusion criteria

* Pregnant or breast-feeding women will not be entered on this study; pregnancy tests must be obtained in girls who are post-menarchal; males or females of reproductive potential may not participate unless they have agreed to use two effective methods of birth control, including a medically accepted barrier or contraceptive method (e.g., male or female condom) for the duration of the study; abstinence is an acceptable method of birth control * Patients receiving systemic corticosteroids who have not been on a stable or decreasing dose of corticosteroid for at least 7 days prior to enrollment are not eligible; if used to modify immune adverse events related to prior therapy, \>= 14 days must have elapsed since last dose of systemic corticosteroid; Note: patients who are using topical or inhaled corticosteroids are eligible * Patients who are currently receiving another investigational drug are not eligible * Patients who are currently receiving other anti-cancer agents are not eligible (except leukemia patients receiving hydroxyurea, which may be continued until 24 hours prior to start of protocol therapy) * Patients who are receiving cyclosporine, tacrolimus or other agents to prevent graft-versus-host disease post bone marrow transplant are not eligible for this trial * Patients who have an uncontrolled infection are not eligible * Patients who have received a prior solid organ transplantation are not eligible * Patients who in the opinion of the investigator may not be able to comply with the safety monitoring requirements of the study are not eligible

Design outcomes

Primary

MeasureTime frameDescription
Response (Complete Response or Partial Response) (Part B)Up to 168 daysPer Response Evaluation Criteria In Solid Tumors Criteria (RECIST v1.1) for target lesions and assessed by MRI: Complete Response (CR), Disappearance of all target lesions; Partial Response (PR), \>=30% decrease in the sum of the longest diameter of target lesions; Stable Disease (SD), no new lesions detected and \<20% increase in sum of smallest diameters of lesions; Disease Control Rate = CR + PR + SD
Area Under Curve (AUC)Prior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+Mean and standard deviation for the area under the drug concentration over time curve by dose level and study part.
ClearancePrior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+Mean and standard deviation for the rate of elimination of the drug by dose level and study part.
Disease Control Rate (Part A)Up to 4 monthsPer Response Evaluation Criteria In Solid Tumors Criteria (RECIST v1.1) for target lesions and assessed by MRI: Complete Response (CR), Disappearance of all target lesions; Partial Response (PR), \>=30% decrease in the sum of the longest diameter of target lesions; Stable Disease (SD), no new lesions detected and \<20% increase in sum of smallest diameters of lesions; Disease Control Rate = CR + PR + SD
Number of Participants With Dose Limiting ToxicitiesUp to 28 daysFrequency (%) of patients with dose limiting toxicities by dose level and study part.
Patients Who Had Grade 3 or Above Toxicities With the Three Attributions, 'DEFINITE', 'POSSIBLE','PROBABLE'Up to 28 daysFrequency of patients experiencing at least grade 3 toxicity according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 by dose level and study part.
Half-lifePrior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+Mean and standard deviation for the time required for the serum concentration to fall to 50% of its starting dose by dose level and study part.
Time to Maximum Concentration (T Max)Prior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+Mean and standard deviation for the time at which the maximum (peak) serum concentration occurs by dose level and study part.
Maximum Concentration (C Max)Prior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+Mean and standard deviation for the maximum (peak) serum concentration by dose level and study part.

Secondary

MeasureTime frameDescription
Total Soluble SEMA4DUp to 28 daysMean and standard deviation of blood and serum samples evaluated for total soluble SEMA4D through a qualified enzyme-linked immunosorbent assay (ELISA) assay.
Immunogenicity of PepinemabUp to 3 yearsMean and standard deviation of immunogenicity assessed in serum through a qualified ELISA.
T-lymphocyte SaturationUp to 28 daysMean and standard deviation for blood samples that will be evaluated for T-lymphocyte saturation by VX15/2503 utilizing a validated flow-cytometry based assay on cycle 1 day 28 (prior to cycle 2 day 1).

Countries

United States

Participant flow

Recruitment details

A Phase I/II Study of VX15/2503 in Children, Adolescents, or Young Adults with Recurrent or Relapsed Solid Tumors. This trial studies the side effects and best dose of pepinemab to see how well it works in treating younger patients that have come back after treatment, or do not respond to treatment. Immunotherapy with monoclonal antibodies, such as pepinemab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread.

Pre-assignment details

Part A (phase 1) portion of the study was to determine if Dose Level 1 (DL1), 20mg/kg pepinemab, was the Maximum Tolerated Dose (MTD)/Recommended Phase 2 Dose (RP2D). There were no dose levels above DL1. However, there was a possible lower dose level of 10mg/kg pepinemab if DL1 was too toxic. Since were no patients with dose-limiting toxicities, all patients in Part A PK (Expansion) and Part B (phase 2) received 20mg/kg pepinemab

Participants by arm

ArmCount
Part A
Patients must be ≥ 12 months and ≤ 21 years of age, recurrent or refractory solid tumors are eligible, excluding CNS tumors.
6
Part A PK
Patients must be ≥ 12 months and ≤ 21 years of age, recurrent or refractory solid tumors are eligible, excluding CNS tumors.
6
Part B
Patients must be ≥ 12 months and ≤ 21 years of age, recurrent or refractory solid tumors are eligible, excluding CNS tumors.
14
Total26

Withdrawals & dropouts

PeriodReasonFG000FG001FG002
Overall StudyLack of Efficacy5514
Overall StudyPhysician Decision100

Baseline characteristics

CharacteristicTotalPart A PKPart BPart A
Age, Categorical
<=18 years
16 Participants6 Participants6 Participants4 Participants
Age, Categorical
>=65 years
0 Participants0 Participants0 Participants0 Participants
Age, Categorical
Between 18 and 65 years
10 Participants0 Participants8 Participants2 Participants
Age, Continuous15.2 Year
STANDARD_DEVIATION 7
7.7 Year
STANDARD_DEVIATION 4.2
17.4 Year
STANDARD_DEVIATION 7.1
17.5 Year
STANDARD_DEVIATION 2.3
Ethnicity (NIH/OMB)
Hispanic or Latino
6 Participants1 Participants4 Participants1 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
17 Participants4 Participants8 Participants5 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
3 Participants1 Participants2 Participants0 Participants
Race (NIH/OMB)
American Indian or Alaska Native
0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Asian
1 Participants1 Participants0 Participants0 Participants
Race (NIH/OMB)
Black or African American
3 Participants1 Participants2 Participants0 Participants
Race (NIH/OMB)
More than one race
0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
0 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Unknown or Not Reported
10 Participants1 Participants5 Participants4 Participants
Race (NIH/OMB)
White
12 Participants3 Participants7 Participants2 Participants
Sex: Female, Male
Female
12 Participants2 Participants8 Participants2 Participants
Sex: Female, Male
Male
14 Participants4 Participants6 Participants4 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
EG002
affected / at risk
deaths
Total, all-cause mortality
1 / 60 / 63 / 14
other
Total, other adverse events
6 / 66 / 614 / 14
serious
Total, serious adverse events
4 / 64 / 610 / 14

Outcome results

Primary

Area Under Curve (AUC)

Mean and standard deviation for the area under the drug concentration over time curve by dose level and study part.

Time frame: Prior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+

Population: All toxicity evaluable patients

ArmMeasureValue (MEAN)Dispersion
Part A: 20 mg/kg (Phase 1)Area Under Curve (AUC)46913 hr*ug/mlStandard Deviation 29902
Part A PK: 20 mg/kg (Expansion)Area Under Curve (AUC)41328 hr*ug/mlStandard Deviation 9251
Part B: 20 mg/kg (Phase 2)Area Under Curve (AUC)36811 hr*ug/mlStandard Deviation 17641
Primary

Clearance

Mean and standard deviation for the rate of elimination of the drug by dose level and study part.

Time frame: Prior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+

Population: All toxicity evaluable patients

ArmMeasureValue (MEAN)Dispersion
Part A: 20 mg/kg (Phase 1)Clearance40.03 ml/hrStandard Deviation 34.9
Part A PK: 20 mg/kg (Expansion)Clearance13.4 ml/hrStandard Deviation 4.6
Part B: 20 mg/kg (Phase 2)Clearance33.2 ml/hrStandard Deviation 25.3
Primary

Disease Control Rate (Part A)

Per Response Evaluation Criteria In Solid Tumors Criteria (RECIST v1.1) for target lesions and assessed by MRI: Complete Response (CR), Disappearance of all target lesions; Partial Response (PR), \>=30% decrease in the sum of the longest diameter of target lesions; Stable Disease (SD), no new lesions detected and \<20% increase in sum of smallest diameters of lesions; Disease Control Rate = CR + PR + SD

Time frame: Up to 4 months

ArmMeasureValue (NUMBER)
Part A: 20 mg/kg (Phase 1)Disease Control Rate (Part A)0 participants
Part A PK: 20 mg/kg (Expansion)Disease Control Rate (Part A)0 participants
Primary

Half-life

Mean and standard deviation for the time required for the serum concentration to fall to 50% of its starting dose by dose level and study part.

Time frame: Prior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+

Population: all toxicity evaluable patients

ArmMeasureValue (MEAN)Dispersion
Part A: 20 mg/kg (Phase 1)Half-life281 hoursStandard Deviation 176
Part A PK: 20 mg/kg (Expansion)Half-life221 hoursStandard Deviation 48
Part B: 20 mg/kg (Phase 2)Half-life162 hoursStandard Deviation 64
Primary

Maximum Concentration (C Max)

Mean and standard deviation for the maximum (peak) serum concentration by dose level and study part.

Time frame: Prior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+

Population: All toxicity evaluable patients

ArmMeasureValue (MEAN)Dispersion
Part A: 20 mg/kg (Phase 1)Maximum Concentration (C Max)175 ug/mlStandard Deviation 78
Part A PK: 20 mg/kg (Expansion)Maximum Concentration (C Max)203 ug/mlStandard Deviation 85
Part B: 20 mg/kg (Phase 2)Maximum Concentration (C Max)168 ug/mlStandard Deviation 75
Primary

Number of Participants With Dose Limiting Toxicities

Frequency (%) of patients with dose limiting toxicities by dose level and study part.

Time frame: Up to 28 days

Population: The patients who had DLT in dose escalation course.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Part A: 20 mg/kg (Phase 1)Number of Participants With Dose Limiting Toxicities0 Participants
Part A PK: 20 mg/kg (Expansion)Number of Participants With Dose Limiting Toxicities0 Participants
Part B: 20 mg/kg (Phase 2)Number of Participants With Dose Limiting Toxicities1 Participants
Primary

Patients Who Had Grade 3 or Above Toxicities With the Three Attributions, 'DEFINITE', 'POSSIBLE','PROBABLE'

Frequency of patients experiencing at least grade 3 toxicity according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 by dose level and study part.

Time frame: Up to 28 days

Population: Part A and B Patients

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Part A: 20 mg/kg (Phase 1)Patients Who Had Grade 3 or Above Toxicities With the Three Attributions, 'DEFINITE', 'POSSIBLE','PROBABLE'0 Participants
Part A PK: 20 mg/kg (Expansion)Patients Who Had Grade 3 or Above Toxicities With the Three Attributions, 'DEFINITE', 'POSSIBLE','PROBABLE'1 Participants
Part B: 20 mg/kg (Phase 2)Patients Who Had Grade 3 or Above Toxicities With the Three Attributions, 'DEFINITE', 'POSSIBLE','PROBABLE'3 Participants
Primary

Response (Complete Response or Partial Response) (Part B)

Per Response Evaluation Criteria In Solid Tumors Criteria (RECIST v1.1) for target lesions and assessed by MRI: Complete Response (CR), Disappearance of all target lesions; Partial Response (PR), \>=30% decrease in the sum of the longest diameter of target lesions; Stable Disease (SD), no new lesions detected and \<20% increase in sum of smallest diameters of lesions; Disease Control Rate = CR + PR + SD

Time frame: Up to 168 days

ArmMeasureValue (NUMBER)
Part A: 20 mg/kg (Phase 1)Response (Complete Response or Partial Response) (Part B)0 participants
Primary

Time to Maximum Concentration (T Max)

Mean and standard deviation for the time at which the maximum (peak) serum concentration occurs by dose level and study part.

Time frame: Prior to, at the end of, and 2 hours after infusion on day 1 of cycles 1-2; days 4 & 8 of cycle 1; prior to and the end of infusion on day 15 of cycle 1; prior to start of infusion on day 15 of cycle 2; prior to start of infusion on day 1 of cycles 3+

Population: All toxicity evaluable patients

ArmMeasureValue (MEAN)Dispersion
Part A: 20 mg/kg (Phase 1)Time to Maximum Concentration (T Max)1.9 hoursStandard Deviation 1.1
Part A PK: 20 mg/kg (Expansion)Time to Maximum Concentration (T Max)1.7 hoursStandard Deviation 1
Part B: 20 mg/kg (Phase 2)Time to Maximum Concentration (T Max)1.7 hoursStandard Deviation 0.9
Secondary

Immunogenicity of Pepinemab

Mean and standard deviation of immunogenicity assessed in serum through a qualified ELISA.

Time frame: Up to 3 years

Population: The planned assays for ADA were unable to generate interpretable results due to limitations of the assay which resulted in higher levels of false positive results. These samples were re-run and only one confirmed positive result out of 81 samples, which was considered to be a true positive ADA. Even this one confirmed positive result had a negative titer, which further signifies a possible false positive or very low-level ADA. Therefore, results were determined to be unreliable and invalid.

Secondary

T-lymphocyte Saturation

Mean and standard deviation for blood samples that will be evaluated for T-lymphocyte saturation by VX15/2503 utilizing a validated flow-cytometry based assay on cycle 1 day 28 (prior to cycle 2 day 1).

Time frame: Up to 28 days

Population: All Eligible Patients

ArmMeasureValue (MEAN)Dispersion
Part A: 20 mg/kg (Phase 1)T-lymphocyte Saturation98.06 percent of T-lymphocyte SaturationStandard Deviation 3.15
Part A PK: 20 mg/kg (Expansion)T-lymphocyte Saturation99.05 percent of T-lymphocyte SaturationStandard Deviation 1.69
Part B: 20 mg/kg (Phase 2)T-lymphocyte Saturation92.99 percent of T-lymphocyte SaturationStandard Deviation 13.79
Secondary

Total Soluble SEMA4D

Mean and standard deviation of blood and serum samples evaluated for total soluble SEMA4D through a qualified enzyme-linked immunosorbent assay (ELISA) assay.

Time frame: Up to 28 days

Population: All eligible patients

ArmMeasureValue (MEAN)Dispersion
Part A: 20 mg/kg (Phase 1)Total Soluble SEMA4D25170.43 pg/mLStandard Deviation 5906.46
Part A PK: 20 mg/kg (Expansion)Total Soluble SEMA4D19757.09 pg/mLStandard Deviation 4680.32
Part B: 20 mg/kg (Phase 2)Total Soluble SEMA4D25986.81 pg/mLStandard Deviation 7665.71

Source: ClinicalTrials.gov · Data processed: Feb 22, 2026