• Histologically confirmed invasive carcinoma of the bladder with pure, or any component of, small cell or high grade neuroendocrine features with or without urothelial cancer - localized ≥ cT1-T4aN1

⁃ A formalin-fixed paraffin-embedded (FFPE) tumor specimen in a paraffin block (preferred) or at least 15 slides containing unstained, freshly cut, serial sections should be submitted along with an associated pathology report prior to study enrollment. If less than 15 slides are available, the patient may still be eligible for the study, after Principal Investigator confirmation has been obtained.

⁃ If archival tumor tissue is unavailable or is determined to be unsuitable for required testing, tumor tissue must be obtained from a biopsy performed at screening.

• Medically fit to undergo chemotherapy, immunotherapy and cystectomy

• 18 years old at time of consent

• ECOG performance status of 0 or 1

• Adequate hematologic and end organ function, defined by the following laboratory results obtained within 14 days prior to randomization:

• ANC ≥ 1500 cells/μL without granulocyte colony-stimulating factor support

• Lymphocyte count ≥ 500/μL

• Platelet count ≥ 100,000/μL without transfusion

• Hemoglobin ≥ 9.0 g/dL -patients may be transfused to meet this criterion.

• INR or aPTT ≤ 1.5 × upper limit of normal (ULN) This applies only to patients who are not receiving therapeutic anticoagulation; patients receiving therapeutic anticoagulation should be on a stable dose.

• AST, ALT, and alkaline phosphatase ≤ 2.5 × ULN

• Serum bilirubin ≤ 1.5 × ULN Patients with known Gilbert disease who have serum bilirubin level ≤3 × ULN may be enrolled.

• Serum albumin \>= 25 g/L (2.5 g/dL)

• Negative HIV test at screening (with the following exception: patients with a positive HIV test at screening are eligible provided they are stable on anti-retroviral therapy, have a CD4 count \>= 200/µL, and have an undetectable viral load)

• Negative hepatitis B surface antigen (HBsAg) test at screening

• Negative total hepatitis B core antibody (HBcAb) test at screening, or positive total HBcAb test followed by a negative hepatitis B virus (HBV) DNA test at screening The HBV DNA test will be performed only for patients who have a negative HBsAg test and a positive total HBcAb test.

• Creatinine clearance \>30. Patients receiving cisplatin must have creatinine clearance \>50

• For women of childbearing potential (WOCBP): agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive methods, and agreement to refrain from donating eggs, as defined below:

• Women must remain abstinent or use contraceptive methods with a failure rate of \<1% per year during the treatment period and for 5 months after the final dose of atezolizumab and for 30 days after the final dose of cisplatin/ carboplatin and etoposide. Women must refrain from donating eggs during this same period.

• A woman is considered to be of childbearing potential if she is postmenarchal, has not reached a postmenopausal state (\>= 12 continuous months of amenorrhea with no identified cause other than menopause), and has not undergone surgical sterilization (removal of ovaries and/or uterus). The definition of childbearing potential may be adapted for alignment with local guidelines or requirements.

• Examples of contraceptive methods with a failure rate of \< 1% per year include bilateral tubal ligation, male sterilization, hormonal contraceptives that inhibit ovulation, hormone-releasing intrauterine devices, and copper intrauterine devices.

⁃ The reliability of sexual abstinence should be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the patient. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or postovulation methods) and withdrawal are not adequate methods of contraception.

• For men: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive measures, and agreement to refrain from donating sperm, as defined below:

• With a female partner of childbearing potential who is not pregnant, or a pregnant female partner men who are not surgically sterile must remain abstinent or use a condom plus an additional contraceptive method that together result in a failure rate of \< 1% per year during the treatment period and for 8 months after the final dose of atezolizumab and 120 days after the final dose of etoposide. Men must refrain from donating sperm during this same period.

• The reliability of sexual abstinence should be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the patient. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or postovulation methods) and withdrawal are not adequate methods of contraception.

• Patients who give a written informed consent obtained according to local guidelines

• Patients who received mineralocorticoids (e.g., fludrocortisone), corticosteroids for chronic obstructive pulmonary disease (COPD) or asthma, or low-dose corticosteroids for orthostatic hypotension or adrenal insufficiency are eligible for the study.