Imugene Limited’s (ASX:IMU) (OTCMKTS:IUGNF) ongoing randomised Phase 2 study of HER-Vaxx in Her-2/Neu overexpressing advanced metastatic gastric/GEJ cancer shows positive overall survival (OS) with a Hazard Ratio of 0.418.
The median OS for patients receiving HER-Vaxx plus chemotherapy was 14.2 months, compared to 8.8 months in patients treated with chemotherapy alone.
Phase 2 data represent a clinical proof-of-concept signal for HER-Vaxx when added to chemotherapy and indicate that B-cell activating immunotherapy vaccines can induce clinically active antibody responses.
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Imugene managing director and chief executive director Mrs Leslie Chong said: “I am delighted to report that we have achieved this significant milestone for patients with advanced gastric cancer.
“I am excited that the interim analysis favoured the survival outcome for HER-Vaxx and the IDMC suggested to shorten the study by lowering the number of patients.
“This data represents a clinical proof-of-concept for HER-Vaxx and supports our B-cell activating immunotherapy platform.
“I look forward to updating the market as the data matures.”
No safety concerns
HER-Vaxx Phase 2 interim analysis safety and efficacy data were reviewed at the Independent Data Monitoring Committee (IDMC) meeting.
As a result of the review, the IDMC reported no safety concerns and viewed this preliminary data as strongly in favour of a HER-Vaxx survival effect.
The IDMC provided guidance that it is scientifically and ethically appropriate to reduce the overall number of patients required to complete the study, given the strong signal observed in the data.
Twice as many patients survived
The interim analysis results from the clinical proof-of-concept study, which was designed with a specified 1-sided false positive probability of 0.10, showed twice as many patients survived on the HER-Vaxx plus SOC chemotherapy treatment arm compared to the SOC chemotherapy control arm.
This translated into an overall survival HR of 0.418 (80% 2-sided CI: 0.186, 0.942) with a statistically significant 1-sided p-value of 0.083.
There was no difference in safety events between the two treatment arms, suggesting that HER-Vaxx does not add toxicity to SOC chemotherapy.
The longest HER-Vaxx treated patient remains on therapy and progression-free 16.3 months after dosing.
Historical data from the ToGA Phase 3 study, which examined the effect of Herceptin plus chemotherapy versus chemotherapy alone in advanced gastric cancer, had an overall survival HR of 0.74 for the intent-to-treat analysis of the same patient population of HER2 overexpressing patients included in the HER-Vaxx Phase 2 study.
Details of Phase 2 study
The Phase 2 HER-Vaxx study is designed to measure the efficacy, safety and immune response in 68 patients with metastatic gastric cancer overexpressing the HER-2 protein.
The study is randomised into two arms of either HER-Vaxx plus standard-of-care chemotherapy or standard-of-care chemotherapy alone.
The primary endpoint is overall survival and secondary endpoint will be progression-free survival. Safety, tolerability and immune response will also be measured.
The Phase 2 trial is being conducted at multiple sites across Eastern Europe and India where clinicians have difficulty accessing approved antibody treatments such as Herceptinâ and Perjetaâ marketed by Swiss multinational Roche Holding AG (OTCMKTS:RHHBY).
There is also a high prevalence of gastric cancer in the countries selected.