Promising phase 2 results for HER-Vaxx in gastric cancer

HER-Vaxx added to standard-of-care chemotherapy was associated with an improved overall survival compared with chemotherapy alone in patients with HER2-overexpressing advanced or metastatic gastric/gastroesophageal junction (GEJ) adenocarcinoma. The current phase 2 HERIZON study did not reveal an increase in adverse events with the addition of HER-Vaxx to chemotherapy.

“HER-Vaxx is a B-cell immunotherapy, designed to target tumours that overexpress the HER2/neu receptor,” outlined Dr Tanuj Chawla (Tata Medical Center, India). This novel agent showed promising efficacy data in a phase 1b study [1]. The phase 2, multicentre HERIZON study (NCT02795988) randomised 36 newly diagnosed patients with stage III or IV gastric or GEJ adenocarcinoma 1:1 to 6 cycles of standard-of-care chemotherapy or to chemotherapy plus 50 μg HER-vaxx, administered at days 1 and 15 of cycle 1, day 15 of cycle 2 and 4, and then every 9 weeks until disease progression occurred [2]. Dr Chawla added that the HERIZON study was performed in countries where trastuzumab was not available. The overall survival (OS) was the primary endpoint of this trial.

The safety outcomes showed comparable safety profiles for the 2 treatment regimens, with over grade 3 treatment-emergent adverse events (TEAEs) occurring in 42% of the patients in each arm. Moreover, the treatment discontinuation rate due to TEAEs appeared to be higher in the control arm than in the experimental arm (24% vs 11%).

The OS was significantly improved in patients who were randomised to the HER-Vaxx arm (median OS 14.0 vs 8.3 months; HR 0.56; 80% CI 0.35–0.90; one-sided P=0.054, see Figure). Also, the duration of response appeared to be longer in the HER-Vaxx arm, with 30 weeks, compared with 19 weeks in the control arm. Finally, persistent HER2-specific antibodies were associated with HER-Vaxx administration and correlated with clinical responses.

Figure: Overall survival benefit when HER-vaxx is added to chemotherapy [2]

“With no added toxicity of HER-Vaxx to standard-of-care chemotherapy and promising efficacy data, the current phase 2 study supports further exploration of HER-Vaxx in patients with gastric or GEJ adenocarcinoma,” decided Dr Chawla. The results have initiated the nextHERIZON study (NCT05311176), which further investigates the potential of HER-Vaxx in the gastric cancer population.

1. Wiedermann U, et al. Clin Cancer Res. 2021;27(13):3649–3660.
2. Maglakelidze M, 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. Abstract 289, ASCO GI 2023, 19–21 January, San Francisco, CA, USA.

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Posted on 17 March, 202316 March, 2023