DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed solid tumor, multiple myeloma, or non-Hodgkin's lymphoma

  • Metastatic or unresectable disease
• Standard curative or palliative measures do not exist OR are no longer effective

• Measurable or non-measurable disease

  • Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques OR ≥ 10 mm by spiral CT scan

  • The following are considered nonmeasurable disease:

    • Bone lesions
    • Ascites
    • Pleural or pericardial effusion
    • Lymphangitis cutis or pulmonis
    • Abdominal masses that are not confirmed and followed by imaging techniques
    • Cystic lesions

• Hepatic or renal function meeting 1 of the following criteria*:

  • Bilirubin normal AND SGOT normal AND creatinine clearance ≥ 60 mL/min (cohort 1)
  • Bilirubin > upper limit of normal (ULN) but ≤ 1.5 times ULN AND/OR SGOT > ULN (cohort 2)
  • Creatinine clearance > 40 mL/min but < 59 mL/min (cohort 3)
  • Bilirubin > 1.5 times ULN but ≤ 3 times ULN AND any SGOT (cohort 4)
  • Creatinine clearance > 20 mL/min but < 39 mL/min (cohort 5)
  • Bilirubin > 3 times ULN but ≤ 10 times ULN AND any SGOT (cohort 6)
  • Creatinine clearance < 20 mL/min (cohort 7)
  • Albumin < 2.5 g/dL AND any bilirubin AND any SGOT (cohort 8)
  • Requires hemodialysis AND any creatinine clearance (cohort 9) NOTE: *Patients meeting criteria for > 1 cohort (e.g., elevated bilirubin AND reduced creatinine clearance) are only eligible for enrollment into cohort 8

• Brain metastases allowed provided all of the following criteria are met:

  • Patient is asymptomatic
  • Disease was previously treated
  • Patient is not currently receiving steroid therapy
  • Disease is radiographically stable for ≥ 2 months

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2

Life expectancy

• Not specified

Hematopoietic

• Absolute granulocyte count ≥ 1,500/mm^3
• Platelet count ≥ 75,000/mm^3
• No evidence of bleeding diathesis

Hepatic

• See Disease Characteristics

• No evidence of biliary obstruction

  • Prior treatment with stents or drains for biliary obstruction allowed provided patient has been observed for ≥ 1 week after treatment AND organ dysfunction has stabilized

Renal

• See Disease Characteristics

• No evidence of renal obstruction

  • Prior treatment with stents or drains for renal obstruction allowed provided patient has been observed for ≥ 1 week after treatment AND organ dysfunction has stabilized

Cardiovascular

• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia
• No uncontrolled hypertension

Gastrointestinal

• No GI disease resulting in an inability to take oral medication
• No requirement for IV alimentation
• No active peptic ulcer disease

Other

• Not pregnant or nursing
• Fertile patients must use effective contraception
• No AIDS
• No ongoing or active infection
• No psychiatric illness or social situation that would preclude study compliance
• No other uncontrolled illness

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas, melphalan, or mitomycin)

Endocrine therapy

• See Disease Characteristics
• No concurrent steroids

Radiotherapy

• At least 4 weeks since prior radiotherapy

Surgery

• At least 4 weeks since prior major surgery
• No prior surgical procedures affecting gastrointestinal (GI) absorption

Other

• No concurrent medications known to cause hepatic or renal toxicity (e.g., antiseizure medications or non-steroidal anti-inflammatory agents)
• No concurrent combination antiretroviral therapy for HIV-positive patients
• No other concurrent investigational agents

• No concurrent therapeutic anticoagulation

  • Prophylactic anticoagulation (i.e., low-dose warfarin) of venous or arterial access devices allowed provided requirements for PT, INR, or PTT are met
• No concurrent cytochrome P450 enzyme-inducing antiepileptic drugs (e.g., phenytoin, carbamazepine, or phenobarbital), rifampin, or Hypericum perforatum (St. John's wort)