RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. It is not yet known whether gemcitabine plus CI-994 is more effective than gemcitabine alone for non-small cell lung cancer.

PURPOSE: Randomized phase III trial to compare the effectiveness of gemcitabine with or without CI-994 in treating patients who have advanced non-small cell lung cancer.

OBJECTIVES: I. Determine the efficacy and safety of gemcitabine with or without CI-994 in patients with advanced non-small cell lung cancer.

OUTLINE: This is a randomized, double blind, placebo controlled, multicenter study. Patients are stratified according to performance status and are randomized to one of two treatment arms. Arm I: Patients receive CI-994 orally on days 1-21 and gemcitabine IV over 30 minutes on days 1, 8, and 15. Arm II: Patients receive placebo capsules orally on days 1-21 and gemcitabine as in arm I. Treatment repeats every 28 days as long as medically appropriate (absence of disease progression or unacceptable toxicity).

PROJECTED ACCRUAL: A total of 176 patients will be accrued for this study.

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed recurrent, locally advanced, or metastatic, unresectable non-small cell lung cancer Failed or relapsed after one prior platinum containing regimen (cisplatin or carboplatin) as first line therapy Prior brain metastases allowed if resection and/or radiotherapy completed, no worsening of CNS symptoms, and at least 1 month since prior corticosteroids

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 70-100% Life expectancy: Greater than 12 weeks Hematopoietic: Absolute neutrophil count at least 2,000/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) AST or ALT no greater than 3 times ULN (no greater than 5 times ULN in patients with liver metastases) Renal: Creatinine clearance at least 50 mL/min Other: Able to swallow intact study capsules No active infection No life threatening illness (other than tumor) No prior malignancy within the past 5 years except well controlled nonmelanomatous skin cancer Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy No more than one prior regimen of chemotherapy No prior gemcitabine No prior CI-994 At least 4 weeks since prior maintenance or consolidation therapy (e.g., matrix metalloprotein inhibitors) Endocrine therapy: See Disease Characteristics Radiotherapy: See Disease Characteristics At least 4 weeks since prior radiotherapy to primary site Surgery: Not specified