CompletedNCT01380600Updated Jul 8, 2026Results posted

Phase 1b Dose Escalation Study of Intravenous JX-594 in Metastatic, Refractory Colorectal Carcinoma

A Phase 1 interventional study of Recombinant Vaccinia GM-CSF; RAC VAC GM-CSF (JX-594) in Carcinoma, Colorectal, sponsored by Jennerex Biotherapeutics. Completed at 1 site in South Korea. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-08.

Sponsored by Jennerex Biotherapeutics · Phase 1, Interventional, and Treatment

Phase: Phase 1
Study type: Interventional
Enrollment: 15
Allocation: Not applicable
Ages: 18 Years and older
Sex: All

Study summary

The purpose of this pilot safety study is to evaluate the safety and tolerability of JX-594 (Pexa-Vec) administered intravenously every 2 weeks in colorectal carcinoma patients who are refractory to or intolerant of oxaliplatin, irinotecan, and Erbitux treatments.

Read the detailed description

This is a Phase Ib, open-label, dose-escalation study designed to evaluate the safety and tolerability of Pexa-Vec (JX-594), a vaccinia GM-CSF/thymidine kinase-deactivated virus, administered intravenously in patients with advanced/metastatic colorectal carcinoma (CRC) that is refractory to standard therapy. Vaccinia virus, from which Pexa-Vec is derived, shows a natural selectivity toward cancer relative to normal tissues after intravenous (IV) administration.

The study utilizes a sequential dose-escalating design to determine the maximum tolerated dose (MTD) and/or maximum feasible dose (MFD). Patients will receive 4 biweekly treatments of Pexa-Vec administered by IV infusion over 60 minutes on Days 1, 15, 29, and 43. Patients will be sequentially enrolled into one of three dose cohorts:

Cohort 1: 1 × 10\^6 pfu/kg
Cohort 2: 1 × 10\^7 pfu/kg
Cohort 3: 3 × 10\^7 pfu/kg Three patients will be treated at each dose level unless a dose-limiting toxicity (DLT) is observed, at which point the cohort may be expanded. All patients will receive hydration and will be observed in the clinic and/or hospital for a minimum of 24 hours after each infusion.

In addition to safety endpoints, secondary objectives include the evaluation of Pexa-Vec pharmacokinetics (PK), pharmacodynamics, immune response, and preliminary anti-tumoral activity. Tumor response assessments will be conducted using CT or MRI on Days 29 and 57 (±2 days) based on Response Evaluation Criteria in Solid Tumors (RECIST).

Conditions studied

Carcinoma, Colorectal

Browse trials for

Keywords

Vaccinia
Vaccinia Virus
JX-594
Jennerex
Colorectal Carcinoma
Colorectal cancer
Colon Cancer
Rectal Cancer
Pexa-Vec

In context

Colorectal Neoplasms

5,599 studies on the registry are indexed under Colorectal Neoplasms; 1,459 are open to participants now.

This study's enrollment of 15 is below the median of 77 across 4,123 interventional studies indexed under Colorectal Neoplasms.

Browse Colorectal Neoplasms studies →

Lead sponsor

Jennerex Biotherapeutics is the lead sponsor of 11 studies on the registry; none are open to participants now.

Counted across the registry records on this site, refreshed daily.

Who can participate

Ages eligible: 18 Years and older
Sexes eligible: All
Accepts healthy volunteers: No

Inclusion criteria

Histologically-confirmed, advanced/metastatic colorectal carcinoma
Failed both oxaliplatin and irinotecan based regimens for advanced/metastatic disease (if tumor advanced either immediately or within 3 months of the end of treatment)
Resistance to Erbitux: patients with Ras mutations, or for whom Erbitux has failed (if tumor advanced either immediately or within 3 months of the end of treatment, or there is no response to Erbitux therapy due to a lack of expression of EGFR (epidermal growth factor))
Karnofsky Performance Score (KPS) ≥ 70
Age ≥18 years
Laboratory Safety: WBC ≥ 3,500 cells/mm3 and ≤ 50,000 cells/mm3, ANC ≥ 1,500 cells/mm3, Hemoglobin ≥ 10 g/dL (transfusion allowed), Platelet count ≥ 100,000 plts/mm3,Total bilirubin ≤ 1.5 X ULN, INR ≤ 1.5, AST, ALT ≤ 2.5x ULN (in case of liver metastasis: AST,ALT ≤5.0 x ULN)
Serum chemistries within normal limits (WNL) or Grade 1 (excluding alkaline phosphatase) - If patients are diabetic, a fasting glucose must be done and patients must be > 160 mg/dL.
Patients who, if they are sexually active, are willing and able to refrain from sexual activity for 3 weeks following JX-594 administration. Patients who are willing and able to use a permitted contraceptive for 3 months after the final administration of JX-594.

Exclusion criteria

Exclusion Criteria:

Significant immunodeficiency due to underlying illness (e.g. HIV/AIDS) and/or medication (e.g. systemic corticosteroids)
Known myeloproliferative disorders requiring systemic therapy
History of exfoliative skin condition (e.g. eczema or ectopic dermatitis) requiring systemic therapy
History of acquiring opportunistic infections.
Tumor(s) invading a major vascular structure (e.g. carotid artery)
Tumor(s) in location that would potentially result in significant clinical adverse effects if post-treatment tumor swelling were to occur
Clinically uncontrolled and/or rapidly accumulating ascites, pericardial and/or pleural effusions
History of severe or unstable cardiac disease
Current, known CNS malignancy (history of completely resected or irradiated brain metastases by WBRT or stereotactic radiosurgery allowed)
Administered anti-cancer therapy within 4 weeks prior to first treatment (6 weeks in case of mitomycin C or nitrosoureas)
Use of anti-viral, anti-platelet, or anti-coagulation medication [Patients who discontinue such medications within 7 days prior to first treatment may be eligible for this study.] Low dose aspirin (approximately 81 mg) allowed.
Pulse oximetry O2 saturation \<90% Pulse oximetry O2 saturation \<90% at rest
Experienced a severe systemic reaction or side-effect as a result of a previous smallpox vaccination
Pregnant or nursing
Household contact exclusions:
Women who are pregnant or nursing an infant
Children \< 5 years old
People with skin disease (e.g. eczema, atopic dermatitis, and related diseases
Immunocompromised hosts (severe deficiencies in cell-mediated immunity, including AIDS, organ transplant recipients, hematologic malignancies)

Study design

Phase: Phase 1
Primary purpose: Treatment
Allocation: Not applicable
Intervention model: Single group
Masking: None (open label)
Enrollment: 15 participants (actual)

Study arms

Other
single arm; Dose escalation
Dose escalation 1e6 pfu/kg bw, 1e7 pfu/kg bw, 3e7 pfu/kg bw of Recombinant Vaccinia GM-CSF JX-594
Drug: Recombinant Vaccinia GM-CSF; RAC VAC GM-CSF (JX-594)

Interventions

DrugRecombinant Vaccinia GM-CSF; RAC VAC GM-CSF (JX-594)
Intravenous Dose Range: 1x10\^6 pfu/kg, 1x10\^7 pfu/kg, 3x10\^7 pfu/kg Up to 4 intravenous infusions administered over 60 minutes every 2 weeks.
Also known as: JX-594

What researchers measure

Primary outcomes

Number of Participants Experiencing Dose-Limiting Toxicities (DLTs)
A DLT is defined as any of the following treatment-related adverse events: Grade 4 toxicity, Grade 3 hematologic toxicity for \> 5 days, or Grade 3 non-hematologic toxicities persisting for \> 7 days except for flu-like symptoms that respond to standard therapies. The number of participants with DLTs was used to determine the Maximally-Tolerated Dose (MTD) and/or Maximum-Feasible Dose (MFD) of JX-594.
Time frame: Up to Day 57 (assessed through 14 days following the 4th and final biweekly JX-594 infusion, an average of 8 weeks).
Number of Participants With Treatment-Emergent Adverse Events (TEAEs)
Adverse events were collected and assessed to evaluate safety and tolerability. A Treatment-Emergent Adverse Event (TEAE) is defined as an event with a start date on or after the date of the first dose of study treatment, or an event present at baseline that worsened in severity after the first dose.
Time frame: Up to Day 71 (assessed through 28 days following the 4th and final biweekly JX-594 infusion, an average of 10 weeks).

Secondary outcomes

Number of Participants in Each Best Overall Tumor Response Category Based on RECIST
Anti-tumoral response was evaluated using Response Evaluation Criteria in Solid Tumors (RECIST) on CT or MRI. Categories include: Complete Response (CR) = Disappearance of all target lesions; Partial Response (PR) = \>=30% decrease in the sum of the longest diameters of target lesions; Progressive Disease (PD) = \>=20% increase in the sum of the longest diameters of target lesions or appearance of new lesions; Stable Disease (SD) = Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD.
Time frame: Up to Day 57 (Week 8)
Overall Survival (OS)
Overall survival (OS) was defined as the time from the first dose of Pexa-Vec until death from any cause. For patients not known to have died at the time of the analysis, OS was censored on the date they were last known to be alive.
Time frame: From the first dose of Pexa-Vec until death from any cause, assessed up to 24 months

Results

Posted Jul 8, 2026

Participant flow

Patients with metastatic, refractory colorectal carcinoma who had failed both oxaliplatin- and irinotecan-based prior chemotherapy regimens were recruited at a single study site (Samsung Medical Center) in Seoul, Republic of Korea. The recruitment and study conduct took place between September 08, 2010, and October 18, 2012

Participant flow — Overall Study
Milestone	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg
Started	3	3	9
Completed	2	2	7
Not completed	1	1	2

Outcome measures

PrimaryNumber of Participants Experiencing Dose-Limiting Toxicities (DLTs)

A DLT is defined as any of the following treatment-related adverse events: Grade 4 toxicity, Grade 3 hematologic toxicity for \> 5 days, or Grade 3 non-hematologic toxicities persisting for \> 7 days except for flu-like symptoms that respond to standard therapies. The number of participants with DLTs was used to determine the Maximally-Tolerated Dose (MTD) and/or Maximum-Feasible Dose (MFD) of JX-594.

Time frame:: Up to Day 57 (assessed through 14 days following the 4th and final biweekly JX-594 infusion, an average of 8 weeks).
Reported as:: Count of participants · Participants

Number of Participants Experiencing Dose-Limiting Toxicities (DLTs)
Participants	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg
Number of Participants Experiencing Dose-Limiting Toxicities (DLTs)	0	0	0

PrimaryNumber of Participants With Treatment-Emergent Adverse Events (TEAEs)

Adverse events were collected and assessed to evaluate safety and tolerability. A Treatment-Emergent Adverse Event (TEAE) is defined as an event with a start date on or after the date of the first dose of study treatment, or an event present at baseline that worsened in severity after the first dose.

Time frame:: Up to Day 71 (assessed through 28 days following the 4th and final biweekly JX-594 infusion, an average of 10 weeks).
Reported as:: Count of participants · Participants

Number of Participants With Treatment-Emergent Adverse Events (TEAEs)
Participants	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg
Experienced TEAE	3	3	9
Did NOT Experience TEAE	0	0	0

SecondaryNumber of Participants in Each Best Overall Tumor Response Category Based on RECIST

Anti-tumoral response was evaluated using Response Evaluation Criteria in Solid Tumors (RECIST) on CT or MRI. Categories include: Complete Response (CR) = Disappearance of all target lesions; Partial Response (PR) = \>=30% decrease in the sum of the longest diameters of target lesions; Progressive Disease (PD) = \>=20% increase in the sum of the longest diameters of target lesions or appearance of new lesions; Stable Disease (SD) = Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD.

Time frame:: Up to Day 57 (Week 8)
Reported as:: Count of participants · Participants

Number of Participants in Each Best Overall Tumor Response Category Based on RECIST
Participants	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg
Complete Response	0	0	0
Partial Response	0	0	0
Stable Disease	0	2	5
Progressive Disease	2	0	2
No Post-Baseline Assessment	1	1	2

SecondaryOverall Survival (OS)

Overall survival (OS) was defined as the time from the first dose of Pexa-Vec until death from any cause. For patients not known to have died at the time of the analysis, OS was censored on the date they were last known to be alive.

Time frame:: From the first dose of Pexa-Vec until death from any cause, assessed up to 24 months
Reported as:: Median · months

Overall Survival (OS)
months	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg
Overall Survival (OS)	10.4 (10.19 to 10.61)	5.06 (NA to NA)	10.22 (5.06 to 11.43)

Adverse events

Collected over Up to approximately 24 months (from the first dose until study completion). Non-serious events are listed at a 5% frequency threshold.

Adverse event summary by group
Group	Deaths	Serious	Other
Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	2/3 (66.7%)	0/3 (0%)	3/3 (100%)
Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	1/3 (33.3%)	0/3 (0%)	3/3 (100%)
Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg	5/9 (55.6%)	2/9 (22.2%)	9/9 (100%)

Most frequent serious events

Most frequent serious events
Event	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg
Pneumonia necrotisingInfections and infestations	0/3	0/3	1/9
Disease progressionGeneral disorders	0/3	0/3	1/9

Most frequent other events

Showing 10 of 40

Most frequent other events
Event	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg
PyrexiaGeneral disorders	3/3	3/3	8/9
ChillsGeneral disorders	1/3	3/3	9/9
NauseaGastrointestinal disorders	3/3	2/3	4/9
HeadacheNervous system disorders	2/3	3/3	4/9
Rash pustularInfections and infestations	0/3	0/3	7/9
HypotensionVascular disorders	1/3	1/3	4/9
FatigueGeneral disorders	1/3	1/3	1/9
VomitingGastrointestinal disorders	1/3	0/3	3/9
StomatitisGastrointestinal disorders	0/3	1/3	2/9
DiarrhoeaGastrointestinal disorders	1/3	1/3	1/9

Baseline characteristics

The baseline analysis population is based on the Intent-to-Treat (ITT) population, which includes all enrolled patients who received at least one treatment of Pexa-Vec

Age, Continuous
Age, Continuous(Years)	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg	Total
Mean	46 ± 13.45	56.3 ± 10.97	56.7 ± 13.15	54.5 ± 12.69

Sex: Female, Male
Sex: Female, Male(Participants)	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg	Total
Female	2	2	1	5
Male	1	1	8	10

Race (NIH/OMB)
Race (NIH/OMB)(Participants)	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg	Total
American Indian or Alaska Native	0	0	0	0
Asian	3	3	9	15
Native Hawaiian or Other Pacific Islander	0	0	0	0
Black or African American	0	0	0	0
White	0	0	0	0
More than one race	0	0	0	0
Unknown or Not Reported	0	0	0	0

Region of Enrollment
Region of Enrollment(Participants)	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg	Total
South Korea	3	3	9	15

American Joint Committee on Cancer (AJCC) Staging
American Joint Committee on Cancer (AJCC) Staging(Participants)	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg	Total
Stage IVA	2	0	0	2
Stage IVB	1	3	9	13

KRAS Mutational Status
KRAS Mutational Status(Participants)	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg	Total
Wild-type	2	1	8	11
Mutant	1	1	1	3
Not Assessed	0	1	0	1

Received Smallpox Vaccine
Received Smallpox Vaccine(Participants)	Cohort 1: Pexa-Vec 1 × 10^6 Pfu/kg	Cohort 2: Pexa-Vec 1 × 10^7 Pfu/kg	Cohort 3: Pexa-Vec 3 × 10^7 Pfu/kg	Total
Yes	2	1	1	4
No	0	1	2	3
Unknown	1	1	6	8

Study locations

1 site

Samsung Medical Center
Seoul, South Korea

Updates

Tracking since Sep 25, 2026

No changes since tracking began. The registry record was last updated on Jul 8, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗

Registry details

Key details

Study ID: NCT01380600
Lead sponsor: Jennerex Biotherapeutics
Collaborators: Samsung Medical Center
Responsible party: Sponsor
First posted: Jun 27, 2011
Start date: Sep 8, 2010
Primary completion: Oct 18, 2012
Completion: Oct 18, 2012
Results posted: Jul 8, 2026
Last update: Jul 8, 2026

Study contacts

Young Suk Park, MD

principal investigator · Samsung Medical Center

Oversight

Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.

Follow this study

Get an email when the registry record changes — status, dates, results — or when someone posts here.

Discussion

Questions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.

Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.

Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.

Other studies in this condition

Colorectal Neoplasms→

Other studies from this sponsor

Jennerex Biotherapeutics

Start the discussion