Evaluating the Addition of the Immunotherapy Drug Atezolizumab to Standard Chemotherapy Treatment for Advanced or Metastatic Neuroendocrine Carcinomas That Originate Outside the Lung

Study Purpose

This phase II/III trial compares the effect of immunotherapy with atezolizumab in combination with standard chemotherapy with a platinum drug (cisplatin or carboplatin) and etoposide versus standard therapy alone for the treatment of poorly differentiated extrapulmonary (originated outside the lung) neuroendocrine cancer that may have spread from where it first started to nearby tissue, lymph nodes, or distant parts of the body (advanced) or that has spread from where it first started (primary site) to other places in the body (metastatic). The other aim of this trial is to compare using atezolizumab just at the beginning of treatment versus continuing it beyond the initial treatment. Immunotherapy with monoclonal antibodies, such as atezolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Cisplatin and carboplatin are in a class of medications known as platinum-containing compounds that work by killing, stopping or slowing the growth of cancer cells. Etoposide is in a class of medications known as podophyllotoxin derivatives. It blocks a certain enzyme needed for cell division and DNA repair, and it may kill cancer cells. Giving atezolizumab in combination with a platinum drug (cisplatin or carboplatin) and etoposide may work better in treating patients with poorly differentiated extrapulmonary neuroendocrine cancer compared to standard therapy with a platinum drug (cisplatin or carboplatin) and etoposide alone.

Recruitment Criteria

Accepts Healthy Volunteers Healthy volunteers are participants who do not have a disease or condition, or related conditions or symptoms	No
Study Type An interventional clinical study is where participants are assigned to receive one or more interventions (or no intervention) so that researchers can evaluate the effects of the interventions on biomedical or health-related outcomes. An observational clinical study is where participants identified as belonging to study groups are assessed for biomedical or health outcomes. Searching Both is inclusive of interventional and observational studies.	Interventional
Eligible Ages	18 Years and Over
Gender	All

More Inclusion & Exclusion Criteria

Inclusion Criteria:

- Participants must have histologically-confirmed (local site pathological confirmation sufficient) extrapulmonary poorly differentiated, neuroendocrine carcinoma (NEC) - Participants must have disease that is unresectable or metastatic and not eligible for definitive therapy as deemed per the treating investigator.

- Participants must have radiologically evaluable disease, measurable or non-measurable, per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria.

All measurable and non-measurable lesions must be assessed by CT scan with IV contrast of the chest/abdomen/and pelvis (or CT chest without contrast and MRI abdomen/pelvis with gadolinium contrast, if contraindication to CT iodinated contrast) within 28 days prior to registration. While may be used for routine clinical evaluation, PET scans and bone scans alone are not acceptable for disease assessment while participating in this study. All known sites of disease must be assessed and documented on the Baseline Tumor Assessment Form.

- Participants must have brain MRI (or CT head with contrast if there is contraindication to MRI brain) if clinically indicated within 28 days prior to registration.

Note: Brain imaging is not required in participants without known and/or clinical concern for brain metastases. Participants with asymptomatic central nervous system (CNS) metastases are eligible if one or more of the following apply:

- Participants who have received treatment for brain metastases must have: - No evidence of radiological progression (by MRI brain or CT head with contrast if there is contraindication to MRI brain) within 28 days prior to registration.

- Discontinued all corticosteroids at least 14 days prior to registration.

- Participants with treatment-naive brain lesions must have: - No lesion measuring > 2.0 cm in size in any axis.

- MRI brain or CT head with contrast (if there is contraindication to MRI brain) demonstrating no evidence for mass effect, edema, or other impending neurological compromise within 28 days prior to registration.

- No evidence of radiological progression (by MRI brain or CT head with contrast if there is contraindication to MRI brain) within 28 days prior to registration.

- No need for > 2 mg of dexamethasone (or equivalent of > 10 mg prednisone) per day at time of registration.

- Participants must not have symptomatic central nervous system (CNS) metastases.

- Participants must not have known or suspected leptomeningeal disease.

- Participants with prior history of non-metastatic (localized/locally advanced disease) extrapulmonary poorly differentiated NEC may have had prior platinum-based therapy +/- radiation +/- surgery provided that all therapy was completed >= 6 months prior to registration.

- Participants must discontinue denosumab prior to study registration and plan to replace with a bisphosphonate while on the study.

- Participants must not have had prior treatment for advanced or metastatic NEC EXCEPT one cycle of platinum (carboplatin/cisplatin) + etoposide is allowed prior to registration.

Other chemotherapy regimens are not allowed. For participants with prostate or urothelial NEC, prior chemotherapy for the non-NEC component (e.g. adenocarcinoma or urothelial) is allowed as long as such therapy was completed >= 24 weeks prior to registration and participants have recovered from all prior toxicities to =< grade 1.

- Participants must not have had prior treatment with an anti-PD-1, anti-PD-L1, anti-PD-L2, CD137 agonists, anti-CTLA-4 agent, or any other immune checkpoint inhibitors for any neuroendocrine neoplasm.

Immune checkpoint inhibitors given for other cancer indications are allowed provided last therapy was given at least 12 months prior to study registration.

- Participants must not have received treatment with systemic immunostimulatory agents including, but not limited to, interferon and interleukin2 [IL-2] within 4 weeks or 5 half-lives of the drug (whichever is longer) prior to registration.

- Participants must not have had history of known severe allergy, anaphylactic, or other hypersensitivity reactions to chimeric or humanized antibodies, including to Chinese hamster ovary cell products or to any component of the atezolizumab formulation, cisplatin, carboplatin, or etoposide.

- Participants must not be on active systemic therapy for another cancer with the exception of hormonal therapy including androgen deprivation therapy (e.g., gonadotropin-releasing hormone [GnRH] agonists or antagonists), which can be continued while participants are receiving protocol therapy.

Use of enzalutamide or apalutamide is permitted after completion of chemotherapy and must be held during chemotherapy for participants receiving prior to enrollment. Use of darolutamide is permitted during chemotherapy. Glucocorticoid-containing regimens, including abiraterone, are not permitted.

- Participants must be >= 18 years of age.

- Participants must have a Zubrod performance status of =< 2 within 28 days prior to registration.

- Participants must have a complete medical history and physical exam within 28 days prior to registration.

- Absolute neutrophil count (ANC) >= 1.5 x 10^9 /L (obtained within 14 days prior to registration.