DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed pancreatic cancer

  • Metastatic or recurrent disease
• Measurable disease, defined as ≥ 1 lesion that can be accurately measured in ≥ 1 dimension (longest diameter) ≥ 20 mm by conventional techniques or ≥ 10 mm by spiral CT scan
• Must have tumor specimen (paraffin embedded or fresh frozen) available
• No known brain metastases

PATIENT CHARACTERISTICS:

• Zubrod performance status 0-2
• Life expectancy > 3 months
• WBC ≥ 3,000/mm^3
• ANC ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3
• Total bilirubin ≤ 1.5 times upper limit of normal (ULN)
• AST/ALT ≤ 3 times ULN (≤ 5 times ULN for tumor involvement of the liver)
• Creatinine clearance ≥ 50 mL/min OR creatinine ≤ 1.5 times ULN
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No history of allergic reactions attributed to compounds of similar chemical or biological composition to erlotinib hydrochloride or gemcitabine hydrochloride
• No other malignancy within the past 5 years, except carcinoma in situ, adequately treated nonmelanoma skin cancer, or other malignancy treated ≥ 5 years ago with no evidence of recurrence

• No concurrent uncontrolled illness including, but not limited to, the following:

  • Ongoing or active infection
  • Symptomatic congestive heart failure
  • Unstable angina pectoris
  • Cardiac arrhythmia
  • Uncontrolled hypertension
  • Psychiatric illness or social situation that would limit compliance with study requirements
• No HIV positivity

PRIOR CONCURRENT THERAPY:

• More than 6 months since prior adjuvant chemotherapy
• No prior gemcitabine hydrochloride or erlotinib hydrochloride
• No prior chemotherapy for metastatic or recurrent disease
• No other concurrent antineoplastic or antitumor therapy, including chemotherapy, radiotherapy, immunotherapy, or hormonal anticancer therapy
• No other concurrent investigational agents
• No concurrent combination antiretroviral therapy