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Oxxon Therapeutics Inc.' Hi-8(TM) MEL Therapeutic Vaccine Demonstrates Potential For Treatment Of Advanced Metastatic Melanoma

6/6/2006 11:27:21 AM

ATLANTA and OXFORD, England, June 6 /PRNewswire/ -- Oxxon Therapeutics today presents data from its Phase II clinical study of its novel Hi-8(TM) MEL therapeutic vaccine in patients with advanced non-resectable melanoma, at the 42nd Annual Meeting of the American Society of Clinical Oncology (ASCO) in Atlanta, GA.

The Phase II dose-escalation study has met its clinical endpoints, demonstrating that immunisation with Oxxon's Hi-8(TM) MEL therapeutic vaccine is well tolerated at all doses and shows clinical benefit in HLA-A2 positive patients.

The study found that patients receiving any dose of Hi-8TM MEL who developed a CD8+ response specific to Melan-A (one of seven melanoma-specific epitopes used in the Hi-8(TM) MEL treatment) in the first 16 weeks had a median survival of 86 weeks compared to 37 weeks for immunological non-responders (p<0.001). For control purposes a cohort of comparable patients that were HLA-A2 negative and received standard care were followed and had a median survival of 42 weeks.

Furthermore, high doses of Hi-8TM MEL induced melanoma-specific CD8+ T-cell responses in 91% of patients so treated, as measured by tetramer staining. Importantly, higher boosting doses were associated with an increase in the magnitude and duration of responses and the proportion of patients showing such an immune response.

Tumour responses were seen in nearly 20% of patients (including one partial response lasting more than 12 months and seven cases with stable disease lasting more than six months). Seven out of the eight patients showing a tumour response (87%) had generated a melanoma-specific CD8+ T-cell response following treatment with Hi-8(TM) MEL. Two of these patients have seen no disease progression for 18 months and 26 months, respectively, following treatment and continue to receive Hi-8(TM) MEL boost immunisations.

Prof. Robert Hawkins of The Christie Hospital, Manchester, UK, who presented the data, said, "Development of an effective therapeutic vaccine for patients with advanced melanoma is an important undertaking. A vaccine that improved survival in these patients would add a critical new treatment to our armamentarium. The data from this trial are very encouraging and I look forward to new studies that may confirm the results from the trial we are reporting today."

Dr Joerg Schneider, Vice President and Director of Research at Oxxon, said, "These data provide a strong indication of the potential of our Hi-8(TM) MEL therapeutic vaccine as a treatment for advanced metastatic melanoma. Our next step is to discuss with regulators the design of further clinical trials to confirm the encouraging results presented at ASCO and to provide a path towards product registration."

John Berriman, Executive Deputy Chairman of Oxxon, added, "These results, following so closely behind the positive Phase II data we recently presented on our Hi-8(TM) HBV treatment for Hepatitis B, further support the value of our Hi-8(TM) PrimeBoost(TM) proprietary platform across a number of therapeutic indications."

The Study Design and Further Results

Hi-8(TM) MEL for the treatment of melanoma is a two-step procedure: the first step involves the administration of a plasmid DNA vaccine expressing seven epitopes derived from five melanoma antigens (Melan-A, MAGE-1, MAGE-3, NY-ESO-1 & tyrosinase), which primes a population of cytotoxic CD8+ T cells; the second step significantly amplifies the CD8+ T-cell response through the administration of a viral vector (MVA) expressing the same epitopes as the plasmid DNA prime. This highly expanded population of antigen-specific CD8+ T-lymphocytes is anticipated to suppress tumour growth.

This Phase II clinical study was a dose-escalation study evaluating increasing doses (5x10 (to the power of 7) to 1x10 (to the power of 9) pfu) and two regimens (six or nine weeks) of Hi-8(TM) MEL therapeutic vaccine in 41 HLA-A2 positive, stage III/IV melanoma patients with non- resectable disease.

Immunisations were administered every three weeks for six or nine weeks initially with continued MVA boosting for patients without evidence of tumour progression at weeks 16 and 24. Epitope-specific CD8+ T-cell responses were assessed pre- and post-immunisation at eight-week intervals until disease progression using IFN-gamma ELISPOT and tetramer assays. Tumour responses were assessed using the RECIST criteria at eight-week intervals until disease progression and overall survival was determined.

Overall survival was also determined for 23 HLA-A2 negative patients that were not eligible for inclusion in the study and received standard of care for comparison.

In addition to those results outlined above, other important results from the trial include:

- Median survival for patients receiving Hi-8TM MEL was 51 weeks compared to 26 weeks for patients that received the MVA component alone (p=0.024)

- Patients receiving MVA alone failed to show strong immune responses, failed to generate any tumour response and median survival (26 weeks) was less than that for patients receiving standard care (42 weeks).

- 71% of patients receiving Hi-8TM MEL followed by additional MVA boosts at 16 weeks and 24 weeks showed a continued Melan-A specific immune response despite a dose related anti-MVA antibody response.

The trial was conducted at seven outpatient study centres in the UK and Germany.

For further information and to download the poster, please visit

About Oxxon Therapeutics

Oxxon Therapeutics (Oxxon), based in Oxford, UK, is advancing the next generation of innovative immunotherapeutics to treat patients with chronic infectious diseases and cancer. To date, the Company has built a pipeline through its proprietary Hi-8(TM) PrimeBoost(TM) platform, an approach that allows rapid development of products that selectively stimulate and enhance a potent protective cellular response in the patient. The Company has development programmes in hepatitis, melanoma and HIV, two of which have just completed early Phase II clinical trials. In addition, the Company is leveraging its enabling platform through partnerships with companies and academic collaborations.

Oxxon Therapeutics

CONTACT: John Berriman, Executive Deputy Chairman; Dr Joerg Schneider,Vice President/Director of Research, +44-1865-398100, MarkSwallow PhD, Citigate Dewe Rogerson, +44-207-638-9571,

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