Aphton Corporation Reports Positive Final Results in Phase II Trial of G17DT in Combination With Cisplatin and 5-FU in Patients With Advanced Gastric Cancer.

Business Editors/Health/Medical Writers

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MIAMI--(BUSINESS WIRE)--Feb. 5, 2004

Aphton Corporation (Nasdaq:APHT) today announced final results from its Phase II single-arm clinical trial of G17DT in combination therapy with cisplatin and 5-FU in patients with advanced gastric (stomach) cancer.

The Phase II trial enrolled a total of 103 chemotherapy-naive patients with advanced gastric cancer from 42 sites in the United States and Europe. Patients received G17DT in combination with cisplatin and 5-FU. G17DT was given at a dose of 500mcg on weeks 1, 5 and 9 with an additional dose at 6 months. Cisplatin was given at a dose of 100mg/m2 during the first day of each 4-week treatment cycle with 5-FU given at a dose of 1000mg/m2/day during the first five days of each 4-week treatment cycle.

The trial included male and female patients over 18 years of age with histologically confirmed adenocarcinoma of the stomach or esophagogastric junction. All patients were chemotherapy naive with measurable metastatic disease and were not suitable for tumor resection with curative intent. All patients must have had a life expectancy of at least 3 months and a Karnofsky index for performance status (KPS), a measure of general health status, of greater than or equal to 70%. Baseline demographic data and health status of patients recruited in the trial were typical of this disease and consistent with published epidemiological studies.

The primary end-point of the trial as specified by the protocol was tumor response by radiographic assessment. Secondary endpoints included evaluation of progression free survival, overall survival, the relationship of immune responsiveness to G17DT and clinical efficacy and safety and tolerability of G17DT in combination with cisplatin and 5-FU. Further analyses investigated the independence of the immune response to G17DT from other clinical parameters. The following results were obtained on the intent to treat population (ITT):

-- Best overall tumor response rate was 51% (49% partial

responders, 2% complete responder) as measured by RECIST 

criteria. Stable disease was 31% with progressive disease 18%.

Confirmed tumor response rate was 28% (partial 27%, complete

1%) with stable disease 48% (ITT).

-- The one year survival for patients treated with the

combination was approximately 19% (ITT).

-- Median survival for patients treated with the combination was

8.9 months (ITT).

-- Median progression free survival was 5.3 months (ITT).

-- Importantly, patients who generated anti-G17 antibodies (N =

79) lived significantly longer than patients who did not

generate anti-G17 antibodies (N=24). Analysis of the Kaplan

Meier plots showed that G17 responders had a median survival

of 10.0 months compared to 3.3 months for G17 non responders

(p less than 0.0001, log rank).

-- A sub-group analysis based on KPS, ranging from 70-100, showed

that the survival benefit of G17 responders compared to G17

non-responders remained statistically significant (p less than

0.0001, log rank). At each KPS stratum, G17 responders lived

significantly longer than G17 non-responders. This indicates

that the survival benefit of G17 responders compared to

non-responders was not solely a function of health status.

-- At each KPS level among the G17 non-responders there were

anti-DT antibody responders, indicating that many of the G17

non-responders were immunocompetent, providing a separate

indication that survival benefit was not a function of health

status.

-- Baseline laboratory values indicative of health status were

similar in both responder and non responder sub-groups

providing an additional indication that survival benefit was

not a function of health status.

-- The addition of G17DT did not exacerbate the known systemic

toxicity profile of cisplatin and 5-FU.

"Gastric cancer is one of the most devastating and aggressive forms of cancer," said Paul Broome, MD Aphton's VP, European Medical Director. "The results from this trial suggest that G17DT could provide a safe, effective addition to the standard of care, cisplatin and 5-FU, for the significant number of patients worldwide that have this terrible disease. We believe that these data support the addition of G17DT to chemotherapy for the treatment of gastric cancer."

"The data from this trial are quite encouraging for patients who suffer from gastric cancer," stated Jaffer Ajani, M.D., from the MD Anderson Cancer Center. "There is no approved therapy for gastric cancer and current standards of care add only a small clinical benefit at a cost of significant side-effects. The data shown in this trial marks a critical step in adding a safe, targeted biological approach to existing therapies to attack this typically fatal life-threatening disease."

About G17DT

Aphton's anti-gastrin targeted immunotherapy induces in patients antibodies that bind to both gastrin 17 and gly-gastrin 17 and remove them from circulation before they can bind to the cancer cell and initiate cell growth. Gastrin 17 and gly-gastrin 17 are believed to be central growth factors, or the initiating signals, for cell growth, cell proliferation and metastasis, or spread, in pancreatic, gastric (i.e. stomach), esophageal, colorectal and other gastrointestinal (GI) system cancers. This signaling cascade is triggered by gastrin binding to the large numbers of gastrin receptors which appear, de novo, in the great majority of cases, on tumor cell surfaces of the gastrointestinal system. Interrupting this process by immunizing the patient with Aphton's anti-gastrin immunogen is specifically targeted immunotherapy. This specificity of targeting only cancer cells occurs because gastrin is not normally secreted and gastrin receptors are not normally found on cells in the GI system, unless they are malignant, or on the path to malignancy (except for cells involved with normal acid secretion).

Recent findings have shown that inhibiting gastrin inhibits cell growth, proliferation and metastasis, leading to programmed cell death (apoptosis). This tilts the balance from cell growth to cell suicide. Gastrin also stimulates the secretion and expression of other important growth factors and receptors within and on the surfaces of the cancer cells involved in tumor growth. Hence, inhibiting gastrin inhibits all of the foregoing factors that contribute to tumor growth and spread, resulting in tumor cell death. Aphton's anti-gastrin targeted immunotherapy would add a biological dimension to the treatment of gastrointestinal cancers.

About Gastric Cancer

There is only one large, randomized, phase III clinical trial that has been reported in the medical literature with cisplatin plus 5 FU for patients with advanced gastric cancer. In that trial the tumor response rate was 20%, as reported by the European Organization for Research and Treatment of Cancer (EORTC) which conducted the trial. While Aphton's data are not directly comparable to the EORTC study we believe that the results reported by Aphton today do compare favorably with those results.

It is estimated that there are approximately 570,000 patients with gastric cancer in the US, Europe and Japan, alone. The prognosis for the overwhelming majority of these patients is very poor. Patients diagnosed with metastatic disease have five-year survival rates of only about three percent. Surgery and chemotherapy are the primary treatment options currently, but have shown only very limited benefit. Aphton believes that its anti-gastrin targeted immunotherapy approach has the potential to extend patient survival without adding systemic toxicity to the chemotherapy regimen.

Aphton Corporation is a biopharmaceutical company developing products using its innovative targeted immunotherapy technology for neutralizing hormones that participate in gastrointestinal system and reproductive system cancer and non-cancer diseases. Aphton has strategic alliances with Aventis Pasteur for treating gastrointestinal system and other cancers with G17DT in North America and Europe; GlaxoSmithKline for reproductive system cancer and non-cancer diseases worldwide

This press release includes forward looking statements, including statements 1) the Company's belief that the results from this trial demonstrate that G17DT provides a safe, effective addition to the standard of care, cisplatin and 5-FU, for patients with gastric cancer; 2) the Company's belief that the data from this clinical trial supports initiation of worldwide Phase III trials of G17DT; and 3) the Company's belief that its anti-gastrin targeted immunotherapy approach has the potential to extend patient survival without adding toxicity to the chemotherapy regimen. These forward-looking statements may be affected by the risks and uncertainties inherent in the drug development process and in the Company's business. This information is qualified in its entirety by cautionary statements and risk factor disclosure contained in the Company's Securities and Exchange Commission filings, including the Company's report on Form 10-K filed with the Commission on March 31, 2003. The Company wishes to caution readers that certain important factors may have affected and could in the future affect the Company's beliefs and expectations and could cause the actual results to differ materially from those expressed in any forward-looking statement made by or on behalf of the Company. These risk factors include, but are not limited to, (1) any modifications to the data arising in connection with preparing the registration of G17DT; (2) our ability to obtain regulatory approval for G17DT or produce G17DT in commercial quantities and gain commercial acceptance, (3) our ability to fund the registration and commercialization of G17DT; (4) intellectual property risks, (5) the impact of competitive products and pricing, and (6) changing economic conditions. The Company undertakes no obligation to update forward-looking statements to reflect events or circumstances after the date hereof.