A Study of IMU-131 (HER-Vaxx) in Combination With Chemotherapy or Pembrolizumab in Patients With Metastatic HER2/Neu Over-Expressing Gastric Cancer (nextHERIZON)

Phase 2

Terminated

• Conditions: Gastric Cancer; Stomach Adenocarcinoma; Stomach Cancer; Gastric Adenocarcinoma; Cancer of Stomach; Gastroesophageal Junction Adenocarcinoma
• Interventions: Biological: IMU-131; Drug: Ramucirumab plus Paclitaxel; Biological: Pembrolizumab

• Registration Number: NCT05311176
• Lead Sponsor: Imugene Limited

Brief Summary

This is a Phase 2, signal generating, open-label, 2-Arm, non-randomized study, in patients with metastatic HER2/neu over-expressing gastric cancer or gastroesophageal adenocarcinomas.

Detailed Description

It is hypothesized that the introduction of HER-Vaxx after 1L treatment in patients that have progressed under trastuzumab may overcome potential resistance against trastuzumab in combination with chemotherapy and can be continued after chemotherapy is terminated. Based on pre-clinical data HER-Vaxx may also synergize with pembrolizumab and therefore serve as a potentially better tolerated and chemotherapy-free treatment opportunity in metastatic patients that progressed under their previous therapy.

The study is designed to generate safety data and efficacy signals to support further development of HER-Vaxx in ≥2L mGC/GEJ cancer after progression with trastuzumab.

The study includes two treatment arms that will be analyzed independently using a 2-Stage design:

* Arm 1: HER-Vaxx in combination with chemotherapy (ramucirumab plus paclitaxel)

* Arm 2: HER-Vaxx in combination with pembrolizumab.

All patients must have received trastuzumab and progressed after 1L to be eligible for enrolment. Patients who have received an immune checkpoint inhibitor (ICI) previously will exclusively be enrolled in Arm 1 (HER-Vaxx + chemotherapy). Patients who are naïve to ICI treatment will exclusively be enrolled into Arm 2 (HER-Vaxx + pembrolizumab).

Study Timeline

• Study First Submitted: 2022-03-08
• Study First Submitted QC: 2022-03-27
• Study First Posted: 2022-04-05
• Study Start: 2022-08-17
• Status Verified: 2024-02
• Primary Completion: 2024-04-04
• Study Completion: 2024-04-04
• Results First Submitted: 2025-03-31
• Results First Submitted QC: 2025-04-25
• Last Update Submitted: 2025-04-25
• Results First Posted: 2025-05-11
• Last Update Posted: 2025-05-11

Recruitment & Eligibility

• Status: TERMINATED
• Sex: All
• Target Recruitment: 7

Inclusion Criteria

1. Age ≥ 18 years with confirmed diagnosis of advanced or metastatic HER2/neu overexpressing gastric or GEJ adenocarcinoma;
2. Progressed on or after trastuzumab therapy;
3. Eastern Cooperative Oncology Group (ECOG) performance status 0-1;
4. Life expectancy of a minimum of 3 months;
5. At least one measurable lesion as defined by RECIST 1.1 criteria and assessed by the local investigator;
6. HER2/neu overexpression assessed using post-progression fresh or archival tissue, or post-progression pathology report;
7. Adequate left ventricular ejection function at baseline, defined as left ventricular ejection fraction (LVEF) > 50% by echocardiogram or Multi Gated Acquisition (MUGA) scan;
8. Adequate hematologic, liver and renal function;
9. A female patient of childbearing potential must agree to use a highly effective method of contraception throughout the study and for at least 120 days after the last dose of assigned treatment.

Exclusion Criteria

1. Previous malignant disease (other than primary malignancy) within the last 5 years, except basal or squamous cell carcinoma of the skin or cervical carcinoma in situ;
2. Concurrent active malignancy except for adequately controlled limited basal cell carcinoma of the skin;
3. Systemic chemotherapy or major surgery within 28 days before starting study treatment and recovered from all adverse events ≤ Grade 1 or baseline with possible exceptions for neuropathy and endocrine-related AEs;
4. Received prior radiotherapy within 2 weeks of start of study treatment and recovered from all radiation-related toxicities and not require corticosteroids; or history of radiation pneumonitis.
5. Previous treatment with trastuzumab-deruxtecan or any other anti-HER2 therapy (except trastuzumab);
6. Clinically significant cardiovascular disease, or other diseases that in the Investigator's opinion may influence the patient's tolerance to study treatment;
7. Pleural effusion or ascites requiring more than weekly drainage;
8. Prior organ transplantation, including allogenic stem-cell transplantation;
9. Chronic immunosuppressive therapy within 7 days prior the first dose of study drug;
10. Active, known, or suspected autoimmune disease;
11. History of (non-infectious) pneumonitis / interstitial lung disease that required steroids or has current pneumonitis / interstitial lung disease;
12. Positivity for human immunodeficiency virus (HIV) (HIV 1/2 antibodies) or active hepatitis B (HBsAg reactive) or active hepatitis C (HCV ribonucleic acid [RNA] qualitative) infection;
13. Current participation or has participated in a study of an investigational agent or has used an investigational device within 4 weeks prior to the first dose of study treatment;
14. Any vaccination within 30 days prior to starting study treatment;
15. Pregnant or lactating females;
16. Arm 2 only: Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 agent;
17. Arm 2 only: Has received prior therapy with an ICI or with an agent directed to another stimulatory or co-inhibitory T-cell receptor (e.g., CTLA-4, OX 40, CD137) and was discontinued from treatment due to a grade 3 or higher adverse event.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Arm 1: HER-Vaxx in combination with chemotherapy (ramucirumab plus paclitaxel)	Ramucirumab plus Paclitaxel	Patients who have received an immune checkpoint inhibitor (ICI) previously will exclusively be enrolled in Arm 1 treated with HER-Vaxx (IM) in combination with chemotherapy (ramucirumab plus paclitaxel)
Arm 1: HER-Vaxx in combination with chemotherapy (ramucirumab plus paclitaxel)	IMU-131	Patients who have received an immune checkpoint inhibitor (ICI) previously will exclusively be enrolled in Arm 1 treated with HER-Vaxx (IM) in combination with chemotherapy (ramucirumab plus paclitaxel)
Arm 2: HER-Vaxx in combination with pembrolizumab	Pembrolizumab	Arm 2 will investigate the combination of HER-Vaxx plus pembrolizumab in patients who are naïve to ICI treatment including patients who have had chemotherapy only treatment after progression on trastuzumab. As the combination treatment has not been investigated, Arm 2 is planned to initiate with a safety run-in phase.
Arm 2: HER-Vaxx in combination with pembrolizumab	IMU-131	Arm 2 will investigate the combination of HER-Vaxx plus pembrolizumab in patients who are naïve to ICI treatment including patients who have had chemotherapy only treatment after progression on trastuzumab. As the combination treatment has not been investigated, Arm 2 is planned to initiate with a safety run-in phase.

Primary Outcome Measures

Name	Time	Method
Number of Participants With Treatment-emergent Adverse Events (TEAEs)	First dose of study drug up to approximately 1.5 years	An AE was defined as any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. A summary of other non-serious AEs and all serious AEs, regardless of causality is located in the Reported AE section.
Number of Participants With Immune-related Adverse Events (irAEs)	First dose of study drug up to approximately 1.5 years	irAEs were monitored throughout the study as per National Comprehensive Cancer Network® (NCCN) guidelines. irAEs were defined as any Grade ≥3 event that did not resolve to Grade 1 (or baseline) within 7 days from the onset of the event, or any Grade ≥3 organ toxicity involving major organ systems that persisted for greater than 72 hours.
Number of Participants With Objective Response	Up to approximately 6 months	Objective response was defined as the number of participants achieving a confirmed best overall response of complete response (CR) or partial response (PR) according to Response Evaluation Criteria for Solid Tumors, Version 1.1 (RECIST v1.1).; * CR: Disappearance of all target lesions.; * PR: At least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters.

Secondary Outcome Measures

Name	Time	Method
Overall Survival (OS)	Up to approximately 6 months	Overall Survival (OS) was defined as the time from first dose of study drug to death due from any cause.
Progression Free Survival (PFS)	Up to approximately 6 months	PFS was defined as the time from first dose of study drug to first documentation of progressive disease (PD) based on RECIST 1.1, or to death from any cause.; PD: At least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study.
Duration of Response (DoR)	Up to approximately 6 months	DoR was measured from earliest CR or PR until first documentation of PD based on RECIST 1.1 or death due to any cause.

Trial Locations

Locations (7)

National Taiwan University Hospital; 🇨🇳 Taipei, Taiwan

Kaohsiung Medical University Hospital; 🇨🇳 Kaohsiung City, Taiwan

National Cheng Kung University Hospital; 🇨🇳 Tainan City, Taiwan

Southern Medical Day Care Centre; 🇦🇺 Wollongong, New South Wales, Australia

The Queen Elizabeth Hospital; 🇦🇺 Woodville South, South Australia, Australia

Taipei Veterans General Hospital; 🇨🇳 Taipei, Taiwan

Chang Gung Memorial Hospital, Linkou; 🇨🇳 Taoyuan City, Taiwan