The primary objective of this study is to ascertain whether there is evidence of longer survival relative to the control arm for three comparisons: 600 mg OGX-427 Arm to control Arm; 1000 mg OGX-427 Arm to control Arm; and pooled 600 mg and 1000 mg OGX-427 Arms to control Arm.

Following 3 loading doses, participants receive chemotherapy and study drug on a 21-day cycle during the Treatment Period (Chemotherapy Period) until disease progression, completion of 6 cycles, toxicity or voluntary participant withdrawal. Participants who do not have documented disease progression and have completed a minimum of four cycles of chemotherapy continue to receive weekly Study Drug maintenance therapy during the Maintenance Period until disease progression or the participant fulfills one of the other reasons for withdrawal from protocol treatment, unless they have been discontinued from protocol treatment for unacceptable toxicity related to study drug. All participants have an End of Treatment (EOT) visit when they are withdrawn from all study treatment (chemotherapy and maintenance). All participants are followed until documented disease progression. Once disease progression is documented, participants enter a Survival Follow-up Period during which data are collected regarding further cancer therapy, secondary malignancy, and survival status.

Inclusion Criteria:

1. Age ≥ 18 years at the time of consent

2. Histologically documented metastatic or locally inoperable advanced transitional cell carcinoma (TCC) of the urinary tract (bladder, urethra, ureter and renal pelvis) (T4b, N2, N3 or M1 disease) NOTE: Certain mixed histologies that are predominately (≥ 50%) TCC are eligible: squamous, adenocarcinoma, and undifferentiated. Mixed undifferentiated histology requires immunohistochemistry (IHC) consistent with a TCC origin. Mixed small-cell histologies are excluded

3. Measurable disease defined as at least one target lesion that has not been irradiated and can be accurately measured in at least one dimension by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria

4. No prior systemic chemotherapy with the following exceptions:

   • Prior use of radiosensitizing single agent therapy is allowed
   • Prior neoadjuvant and adjuvant chemotherapy may be allowed

5. Minimum of 21 days since prior major surgery or radiation therapy

6. Karnofsky performance status ≥ 70%

7. Required laboratory values at baseline:

   • absolute neutrophil count (ANC) ≥ 1.5 x 10^9 cells/L
   • platelet count ≥ 125 x 10^9/L
   • calculated creatinine clearance ≥ 60 mL/minute
   • bilirubin ≤ 1.5 x upper limit of normal (ULN; ≤ 2.5 x ULN if secondary to Gilbert's disease)
   • aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3.0 x ULN

8. If of child-bearing potential, willing to use contraceptives

9. Willing to give written informed consent

Exclusion Criteria:

1. A candidate for potential curative surgery or radiotherapy
2. Intravesical therapy within the last 3 months
3. Documented brain metastasis or carcinomatous meningitis, treated or untreated. NOTE: Brain imaging is not required unless the patient has symptoms or physical signs of central nervous system (CNS) disease.
4. Peripheral neuropathy ≥ Grade 2
5. Known serious hypersensitivity to gemcitabine, cisplatin or carboplatin
6. Current serious, uncontrolled medical condition such as congestive heart failure, angina, hypertension, arrhythmia, diabetes mellitus, infection, etc. or any condition such as a psychiatric illness which in the opinion of the investigator would make the patient unacceptable for the protocol
7. Cerebrovascular accident, myocardial infarction or pulmonary embolus within 6 months of randomization
8. Active second malignancy (except non-melanomatous skin cancer): active secondary malignancy is defined as a current need for cancer therapy or a high possibility (> 30%) of recurrence during the study
9. Pregnant or nursing (must have a negative serum or urine pregnancy test within 72 hours prior to randomization)
10. Participating in a concurrent clinical trial of an experimental drug, vaccine or device. Participation in an observational study is allowed