Imugene releases encouraging HER-Vaxx trial results

Imugene Limited (ASX:IMU), a leading clinical stage immuno-oncology company, has today released new data on the Phase lb study of its HER-Vaxx cancer vaccine at the American Association for Cancer Research (AACR) 2019 Annual Meeting in Atlanta, Georgia.

The poster (abstract number 8249) was presented by Professor Ursula Wiedermann from the Medical University Vienna, the lead-inventor of the HER-Vaxx cancer vaccine and member of IMU’s Scientific Advisory Board.

Wiedermann provided the update with a well-known research team at the Medical University Vienna.

Highlights of Professor Wiedermann’s presentation include:

• 11 of 14 patients were evaluable for vaccine-specific immune responses and tumor response assessment
• Of the three evaluable patients treated at the highest dose of 50 micrograms in cohort 3, all showed a partial response with two demonstrating greater than 40 per cent reduction in tumor size from baseline to day 56 (eight weeks)
• Patients in cohort three who received the highest dose of 50 micrograms recorded high antibody levels which correlated with clinical responses and reduction in tumor size
• Higher antibody (HER-2 specific IgG) levels were observed in patients in cohort two who received a 30 microgram dose compared to those in cohort one who received a lower 10 microgram dose, showing clear dose-dependence of HER-2 specific antibody production
• Three of five patients in cohort two displayed moderate or little increase in antibody tests. In contrast, all patients in cohort three who received a 50 microgram dose showed a marked increase of HER-2-specific antibody levels after vaccination
• Of the patients evaluable for best response, one showed complete response, five showed a partial response and four showed a stabilisation of their disease
• Antibodies present in the serum of one cohort three patient at day 56 correlated with strong tumor reduction and showed capacity to inhibit HER-2 phosphorylation, one of the key mechanisms of antibody derived anti-tumor effects
• Moreover, in patients with a marked decrease in tumor size, the percentage of T regulatory cells declined
• The vaccine was well tolerated and safe with antibody responses at the highest dose of 50 micrograms with no significant local or systemic reactions
• No serious adverse events related to administration of HER-Vaxx (IMU-131) were reported. A dose of 50 micrograms was recommended for further evaluation in the Phase II trial, featuring two arms of either HER-Vaxx plus chemotherapy or chemotherapy alone.

IMU Managing Director and CEO Leslie Chong commented on the update, “We are encouraged by the overall positive data from the Phase lb trial which clearly supports our B-cell platform cancer vaccine strategy for treating HER-2 positive gastric cancer.”

The abstract presentation was entitled ‘A Phase lb open label multicentre study with a HER-2/neu peptide vaccine administered with cisplatin and 5-fluorouracil or capecitabine chemotherapy shows safety, immunogenicity and clinical response in patients with a HER-2/neu overexpressing advanced cancer of the stomach’.

It was authored by Professor Wiedermann and researchers at the Medical University of Vienna in Austria and IMU.

More data

In addition, IMU announced that Dr Tanios Bekaii-Saab from the Mayo Clinic also presented new data on the KEY-Vaxx and B-Vaxx cancer vaccine programs at the AACR 2019 Annual Meeting.

The key finding of the KEY-Vaxx presentation demonstrated that it, combined with B-Vaxx, is more effective in reducing tumor growth in a validated mouse model of colon carcinoma versus either the PD-1 monoclonal antibody.

This vaccine combination was found to be safe and did not appear to exhibit toxicity or autoimmunity. IMU is now working to evaluate KEY-Vaxx and its potential efficacy in a range of cancers. Its KEY-Vaxx treatment is a B-cell peptide cancer vaccine designed to treat tumors such as lung cancer, by interfering with the PD-1/PD-L1 binding and interaction, and produce an anti-cancer effect similar to other immune checkpoint inhibitor monoclonal antibodies.

The presentations were entitled 'Development of a novel PD-1 vaccine and in combination with two Chimeric HER-2 peptide vaccine provides synergistic inhibition of tumor growth in a syngeneic Balb/c model challenged with CT26/HER-2 carcinoma cell line' and 'A phase 1 Active Immunotherapy Trial With a Combination of Two Chimeric Human Epidermal Growth Factor Receptor 2 (HER-2) B Cell Peptide Vaccine Emulsified in ISA 720 and Nor-MDP Adjuvant in Patients With Advanced Solid Tumors'.

They were authored by Dr Saab (Mayo Clinic Cancer Center, Phoenix, Arizona) and researchers including Professor Kaumaya at the Ohio State University, Colombus, Ohio (and others).

About IMU

IMU’s HER-Vaxx is a B-cell peptide cancer vaccine designed to treat tumors that over-express the HER-2/neu receptor, such as gastric, breast, ovarian, lung and pancreatic cancers.

The immunotherapy is constructed from several B cell epitopes derived from the extracellular domain of HER-2/neu. It has been shown in pre-clinical studies and now in Phase I studies to stimulate a potent polyclonal antibody response to HER-2/neu, a well-known and validated cancer target.

A Phase II HER-Vaxx study was initiated in March 2019.