DISEASE CHARACTERISTICS:

• Histologically confirmed solid tumor

  • Metastatic or unresectable disease
  • Standard curative antineoplastic drug therapy does not exist or is no longer effective
• No known brain metastases

PATIENT CHARACTERISTICS:

• ECOG performance status (PS) 0-2 or Karnofsky PS 60-100%
• Life expectancy > 3 months
• WBC ≥ 3,000/mm³
• Absolute neutrophil count ≥ 1,500/mm³
• Platelets ≥ 100,000/mm³
• Bilirubin normal
• AST/ALT ≤ 2.5 times upper limit of normal
• Creatinine normal OR creatinine clearance ≥ 60 mL/min
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No history of allergic reactions to agents of similar chemical or biological composition to E7389 or gemcitabine hydrochloride

• No uncontrolled intercurrent illness including, but not limited to, any of the following:

  • Ongoing or active infection
  • Symptomatic congestive heart failure
  • Unstable angina pectoris
  • Cardiac arrhythmia
  • Psychiatric illness/social situation that would preclude study compliance

PRIOR CONCURRENT THERAPY:

• Recovered from prior therapy

• At least 4 weeks since prior radiation therapy

  • No more than 40% of bone marrow radiated
  • Must have measurable disease outside the radiation field or show disease progression after prior radiation therapy
• At least 4 weeks since prior major surgery
• At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin C)

• No more than 2 prior chemotherapy regimens for advanced or metastatic incurable solid tumors

  • Prior neoadjuvant chemotherapy is not counted towards the 2 prior chemotherapy regimens
• At least 4 weeks since prior biologic therapy or hormonal therapy
• No prior gemcitabine hydrochloride
• No concurrent combination antiretroviral therapy for HIV-positive patients

• No concurrent inhibitors or inducers of CYP3A4

  • Concurrent use of CYP3A4 substrates allowed
• No concurrent prophylactic colony-stimulating factors
• No other concurrent investigational agents
• No other concurrent anticancer therapy (e.g., hormonal therapy, biologic therapy, or targeted therapies)