In a phase 1b/2 study, the B-lymphocyte-stimulating HER2 vaccine IMU-131 was found to be safe and provide clinical benefit for patients with HER2 overexpressing gastric or gastroesophageal cancer, compared to the standard-of-care chemotherapy.

Results from this study were presented on Thursday, January 19, 2023, at the American Society of Clinical Oncologists Gastrointestinal Cancers Symposium in San Francisco, CA, by Tanuj Chawla, MD, Tata Medical Center, Kolkata, West Bengal, India.

In phase 1b of this study, the safety and tolerability of IMU-131 was determined, as well as the recommended phase 2 dose of IMU-131 in combination with chemotherapy for this patient population. Phase 2 was a dose expansion study, further characterizing safety and the clinical activity of IMU-131 plus chemotherapy, compared with chemotherapy alone.

In the open-label phase 2 study, 36 patients with HER2 overexpressing gastric or gastroesophageal junction adenocarcinoma were randomized to receive either IMU-131 plus the standard of care chemotherapy (n = 19), or standard-of-care chemotherapy alone (n = 17). Both groups received chemotherapy (oxaliplatin plus capecitabine) on day 0 and then every 21 days for a maximum of 6 cycles or until disease progression, while the IMU-131 arm also received a 50 micrograms dose of IMU-131 on days 0, 14, 35, 77, and then every 63 days until disease progression. The primary end point was overall survival (OS).

In the IMU-131 arm, the median OS was 13.9 months, compared to 8.3 months in the chemotherapy alone arm (hazard ratio [HR] 0.580; 80% 2-sided confidence interval [CI], 0.362 to 0.927; P = .066). This resulted in a 42% survival benefit for patients treated with IMU-131 plus chemotherapy compared to those treated with chemotherapy alone. The median duration of response was 30 weeks in the IMU-131 arm and 19 weeks in the chemotherapy alone arm. There was no difference in safety, indicating that IMU-131 does not add any toxicity to the standard-of-care chemotherapy.

First author Marina Maglakelidze, MD, Petre Shotadze Tbilisi Medical Academy, Georgia, and coauthors concluded, IMU-131 “induced persistent HER2-specific antibodies which correlated with clinical response,” adding the data from this trial “demonstrate that in patients with HER2-overexpressing gastric/GEJ cancer active HER2-immunication with [IMU-131] is safe and provides relevant clinical benefit over standard-of-care chemotherapy.”

Source:

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. Presented at 2023 ASCO Gastrointestinal Cancers Symposium; January 19-21, 2023; San Francisco, CA. Abstract 289.