DISEASE CHARACTERISTICS:

• Histologically proven metastatic pancreatic cancer with overexpression of HER2/neu
• Patients in whom there is inadequate tissue to evaluate for HER2/neu overexpression but who have elevated serum HER2/neu antigen levels are eligible

• Radiographically measurable disease

  • May have metastatic disease in which primary lesion is measurable but metastatic lesions are not measurable
  • Ascites is not measurable

PATIENT CHARACTERISTICS:

Age:

• Over 18

Performance status:

• ECOG 0-2

Life expectancy:

• Not specified

Hematopoietic:

• Granulocyte count at least 1,500/mm3
• Platelet count at least 100,000/mm3

Hepatic:

• Bilirubin no greater than 3.0 mg/dL

  • Greater than 3 times normal if increase in bilirubin is due to biliary obstruction from tumor as long as biliary system is stented or bypassed and bilirubin, SGOT, or SGPT is stable or decreasing

• SGOT no greater than 3 times normal

  • No greater than 5 times normal if liver metastases present OR
  • Greater than 5 times normal if increase in SGOT or SGPT is due to biliary obstruction from tumor as long as biliary system is stented or bypassed and biliary SGOT or SGPT is stable or decreasing

Renal:

• Creatinine no greater than 2.0 mg/dL

Cardiovascular:

• No unstable angina
• No prior congestive heart failure
• No prior myocardial infarction
• LVEF at least 45% by MUGA or echocardiogram

Other:

• Not pregnant
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No prior trastuzumab
• No concurrent growth factors

Chemotherapy:

• No prior anthracyclines
• No prior gemcitabine except prior low dose (no greater than 300 mg/m2/week) gemcitabine with radiotherapy
• At least 6 months since prior adjuvant therapy
• More than 2 weeks since other prior chemotherapy
• No other concurrent cytotoxic chemotherapy

Endocrine therapy:

• Not specified

Radiotherapy:

• See Chemotherapy
• More than 2 weeks since prior radiotherapy
• No concurrent radiotherapy

Surgery:

• Not specified

Other:

• No other concurrent investigational agents