Combining HER-Vaxx with standard chemotherapy improves survival in patients with HER2-overexpressing, advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma, according to results from the HERIZON trial.

HER-Vaxx was associated with a nearly 6-month improvement in overall survival (OS), study investigator Tanuj Chawla, MD, of Tata Medical Centre in Kolkata, India, reported at the 2023 ASCO Gastrointestinal Cancers Symposium.

HER-Vaxx is a B-cell immunotherapy designed to treat tumors that overexpress the HER2-neu receptor. Dr Chawla and colleagues tested HER-Vaxx in combination with standard chemotherapy in the phase 2 HERIZON trial ( Identifier: NCT02795988).

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The trial included 36 patients with HER2-overexpressing metastatic or advanced gastric/GEJ adenocarcinoma who were naïve to HER2 therapy. The patients were randomly assigned to receive standard chemotherapy alone (n=17) or with HER-Vaxx (n=19). 

HER-Vaxx was given at 50 µg by intramuscular injection on days 1 and 15 of the first cycle, day 15 of cycles 2 and 4, and then every 9 weeks until disease progression. Chemotherapy was given every 3 weeks for 6 cycles. It consisted of oxaliplatin plus capecitabine, cisplatin plus fluorouracil, or cisplatin plus capecitabine.

Six patients in each arm went on to receive subsequent treatment. There were 5 patients who received trastuzumab (3 in the HER-Vaxx arm and 2 in the chemotherapy-alone arm).

The median OS was 14.0 months in the HER-Vaxx arm and 8.3 months in the chemotherapy-alone arm (hazard ratio, 0.558; 2-sided 80% CI, 0.349-0.895; P =.054). 

The median progression-free survival was 6.93 months in the HER-Vaxx arm and 6.01 months in the chemotherapy-alone arm.

There were 7 responses in each arm. The only complete response occurred in the HER-Vaxx arm. The median duration of response was longer in the HER-Vaxx arm than in the chemotherapy-alone arm — 30 weeks and 19 weeks, respectively.

There was no additive toxicity with HER-Vaxx, Dr Chawla noted. The rate of grade 3 or higher treatment-emergent adverse events (AEs) was 42% in both arms. 

The rate of treatment-related AEs was 84% in the HER-Vaxx arm and 77% in the chemotherapy-alone arm. There was 1 fatal AE in each arm — a case of COVID-19 in the HER-Vaxx arm and a case of respiratory failure in the chemotherapy-alone arm. 

Dr Chawla said the researchers are exploring alternative HER-Vaxx doses in an extension study. They are also testing HER-Vaxx in combination with pembrolizumab or ramucirumab plus paclitaxel in a phase 2 study ( Identifier: NCT05311176). 

Disclosures: The HERIZON study was supported by Imugene Limited. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Maglakelidze M, Ryspayeva DE, Andric Z, et al. HERIZON: A phase 2 study of HER-Vaxx (IMU-131), a HER2-targeting peptide vaccine, plus standard of care chemotherapy in patients with HER2-overexpressing metastatic or advanced gastric/GEJ adenocarcinoma— Overall survival analysis. ASCO GI 2023. January 19-21, 2023. Abstract 289.