Bortezomib in Treating Patients With Unresectable or Metastatic Gastric Cancer or Gastroesophageal Junction Adenocarcinoma

DISEASE CHARACTERISTICS:

* Histologically or cytologically confirmed unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma

  * Siewert's class II or III disease
* Measurable disease

  * At least 1 unidimensionally measurable lesion at least 20 mm by conventional techniques OR at least 10 mm by spiral CT scan
* No history of known or active brain metastases or primary brain tumors

PATIENT CHARACTERISTICS:

Age

* 18 and over

Performance status

* Karnofsky 60-100% OR
* ECOG 0-2

Life expectancy

* Not specified

Hematopoietic

* WBC at least 3,000/mm\^3
* Absolute neutrophil count at least 1,000/mm\^3
* Platelet count at least 100,000/mm\^3

Hepatic

* Bilirubin no greater than 1.5 mg/dL
* AST and ALT no greater than 3 times upper limit of normal (ULN) (5 times ULN if liver metastases are present)

Renal

* Creatinine no greater than 1.5 mg/dL

Cardiovascular

* No prior cerebrovascular event
* No prior orthostatic hypotension
* No myocardial infarction within the past 6 months
* No peripheral vascular disease requiring surgical management
* No evidence of acute ischemia or significant conduction abnormality by EKG

Other

* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception during and for at least 2 months after study participation
* No evidence of peripheral neuropathy
* No prior allergic reaction attributed to compounds of similar chemical or biological composition to bortezomib
* No other malignancy within the past 3 years except basal cell skin cancer, carcinoma in situ of the cervix, or adequately treated nonmetastatic prostate cancer
* No ongoing or active infection
* No psychiatric illness or social situation that would preclude study participation
* No other concurrent uncontrolled illness that would preclude study participation
* No other medical condition or reason that would preclude study participation

PRIOR CONCURRENT THERAPY:

Biologic therapy

* More than 3 weeks since prior immunotherapy
* No concurrent biological or immunological agents

Chemotherapy

* No more than 1 prior chemotherapy regimen (including adjuvant chemotherapy)
* More than 3 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin)
* No concurrent chemotherapy

Endocrine therapy

* Not specified

Radiotherapy

* More than 3 weeks since prior radiotherapy
* No concurrent radiotherapy

Surgery

* Not specified

Other

* Recovered from all prior therapy
* No other concurrent investigational agents
* No other concurrent anticancer agent or therapy