This phase III trial compares the effect of bevacizumab in combination with carboplatin, paclitaxel and pembrolizumab to the usual treatments of carboplatin and paclitaxel with or without pembrolizumab in treating patients with stage III, IVA or IVB mismatch repair protein proficient (pMMR) and TP53 mutated endometrial 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 come back after a period of improvement (recurrent). Bevacizumab is in a class of medications called antiangiogenic agents. It works by stopping the formation of blood vessels that bring oxygen and nutrients to tumor. This may slow the growth and spread of tumor. Carboplatin is in a class of medications known as platinum-containing compounds. Carboplatin works by killing, stopping or slowing the growth of tumor cells. Paclitaxel is in a class of medications called antimicrotubule agents. It stops tumor cells from growing and dividing and may kill them. Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the tumor, and may interfere with the ability of tumor cells to grow and spread. Adding bevacizumab to the combination of carboplatin, paclitaxel and pembrolizumab may be more effective than the usual treatment combinations of carboplatin and paclitaxel with or without pembrolizumab in treating patients with advanced or recurrent pMMR and TP53 mutated endometrial cancer.

PRIMARY OBJECTIVE:

I. To demonstrate that bevacizumab, an anti-VEGF antibody therapy, (or an anti-VEGF antibody biosimilar) in combination with carboplatin, paclitaxel, and pembrolizumab is superior to carboplatin, paclitaxel, and pembrolizumab (the control arm) or carboplatin, paclitaxel, and bevacizumab in prolonging progression-free survival (PFS) in patients with pMMR, TP53 mutated advanced stage (III or IV) or recurrent endometrial cancer.

SECONDARY OBJECTIVES:

I. To demonstrate that bevacizumab in combination with carboplatin, paclitaxel, and pembrolizumab is superior to carboplatin, paclitaxel, and pembrolizumab or carboplatin, paclitaxel, and bevacizumab in prolonging overall survival (OS) in patients with pMMR, TP53 mutated advanced stage (III or IV) or recurrent endometrial cancer.

II. To examine the impact of the addition of bevacizumab in combination with carboplatin and paclitaxel or with carboplatin, paclitaxel, and pembrolizumab on PFS and OS based on type of p53 immunohistochemistry (IHC) aberrancy (over expression/cytoplasmic expression versus null [complete absence of staining]) and mutation type.

III. To evaluate toxicity on treatment with bevacizumab when combined with carboplatin, paclitaxel, and/or pembrolizumab as assessed by Common Terminology Criteria for Adverse Events (CTCAE) version (v.)5.0.

IV. To explore the anti-tumor activity in each treatment arm as assessed by objective response rate in the subset of patients with measurable disease by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1.

OUTLINE: Patients are randomized to 1 of 3 arms.

ARM 1 (REFERENCE ARM): Patients receive paclitaxel intravenously (IV) over 3 hours, carboplatin IV and pembrolizumab IV over 30 minutes on day 1 of each cycle. Cycles repeat every 3 weeks for up to 6-10 cycles in the absence of disease progression or unacceptable toxicity. Starting 3 weeks after last combination phase cycle, patients may continue to receive maintenance pembrolizumab IV over 30 minutes on day 1 of each cycle. Cycles repeat every 6 weeks for up to an additional14 cycles. Additionally, patients undergo urine and blood sample collection and computed tomography (CT) or magnetic resonance imaging (MRI) throughout the study.

ARM 2 (EXPERIMENTAL TRIPLET ARM): Patients receive paclitaxel IV over 3 hours, carboplatin IV, and bevacizumab IV or anti-VEGF antibody biosimilar on day 1 of each cycle. Cycles repeat every 3 weeks for up to 6-10 cycles in the absence of disease progression or unacceptable toxicity. Starting 3 weeks after last combination phase cycle, patients may continue to receive maintenance bevacizumab IV on day 1 of each cycle. Treatment repeats every 3 weeks for up to an additional 28 doses. Additionally, patients undergo urine and blood sample collection and CT or MRI throughout the study.

ARM 3 (EXPERIMENTAL QUADRUPLET ARM): Patients receive paclitaxel IV over 3 hours, carboplatin IV, pembrolizumab IV over 30 minutes, and bevacizumab IV or anti-VEGF antibody biosimilar on day 1 of each cycle. Cycles repeat every 3 weeks for up to 6-10 cycles in the absence of disease progression or unacceptable toxicity. Starting 3 weeks after last combination phase cycle, patients may continue to receive maintenance pembrolizumab IV over 30 minutes every 6 weeks for up to an additional 14 cycles and bevacizumab IV every 3 weeks for up to an additional 28 doses. Additionally, patients undergo urine and blood sample collection and CT or MRI throughout the study.

After completion of study treatment, patients are followed every 3 months for 2 years then every 6 months for up to 3 years.

Inclusion Criteria:

• Documentation of disease:

  • Stage III and stage IVA endometrial cancers (with measurable disease),
  • Stage IVB endometrial cancer (with or without measurable disease), or
  • Recurrent endometrial cancer (with or without measurable disease)

• In patients with measurable disease, lesions will be defined and monitored by RECIST 1.1. Measurable disease (RECIST 1.1) is defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded). Each lesion must be ≥ 10 mm when measured by CT or MRI. Lymph nodes must be ≥ 15 mm in short axis when measured by CT or MRI

• Histologic confirmation of the original primary tumor is required (submission of pathology report[s] is required). Patients with the following histologic types are eligible: endometrioid, serous, dedifferentiated/undifferentiated, clear cell, mixed epithelial, carcinosarcoma, adenocarcinoma not otherwise specified (N.O.S.)

• Patients must have:

  • Tumoral mismatch repair proficient (pMMR) disease as assessed by immunohistochemistry (IHC) AND
  • P53 IHC with aberrant staining pattern (aberrant p53 expression is consistent with mutant TP53). TP53 mutation by next-generation sequencing will also be accepted

• A pathology report demonstrating results of institutional MMR IHC and p53 IHC and/or TP53 by next-generation sequencing

• Patients may have received:

  • NO prior chemotherapy for treatment of endometrial cancer OR
  • Prior adjuvant chemotherapy (e.g., paclitaxel/carboplatin alone or as a component of concurrent chemotherapy and radiation therapy [with or without cisplatin]) provided adjuvant chemotherapy was completed ≥ 12 months prior to registration

• Patients may have received prior radiation therapy for treatment of endometrial cancer. Prior radiation therapy may have included pelvic radiation therapy, extended field pelvic/para-aortic radiation therapy, intravaginal brachytherapy, and/or palliative radiation therapy. All radiation therapy must be completed at least 4 weeks prior to registration. For patients with recent radiation, they must have RECIST-evaluable disease outside of the radiation field and have recovered their marrow function

• Patients may have received prior hormonal (endocrine) therapy. All hormonal (endocrine) therapy must have been completed at least 1 week prior to registration

• NO prior pembrolizumab (or other anti-PD1, anti-PDL1 or anti-CTLA4 therapy) or bevacizumab (or other antiangiogenic therapy)

• Interval or cytoreductive surgery, after start of treatment on this trial, and prior to documentation of disease progression, is NOT permitted

• Patients with treated brain metastases are eligible if follow-up brain imaging after central nervous system (CNS)-directed therapy shows no evidence of disease progression. Patients with brain metastases must have follow up imaging demonstrating no evidence of disease progression and that the disease is stable off of steroids

• Age ≥ 18

• Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 2

• Not pregnant and not nursing

• Absolute neutrophil count (ANC) ≥ 1,500 cells/mm^3

• Platelets ≥ 100,000 cells/mm^3

• Hemoglobin ≥ 8 g/dl

• Creatinine clearance (CrCl) of ≥ 30 mL/min by the Cockcroft-Gault formula

• Total bilirubin ≤ 1.5 x institutional upper limit of normal (ULN) (patients with known Gilbert's disease who have bilirubin level ≤ 3 x institutional ULN may be enrolled)

• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3 x institutional ULN

• Patients with known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, should have a clinical risk assessment of cardiac function using the New York Heart Association Functional Classification. To be eligible for this trial, patients should be class II or better

• No active infection requiring parenteral antibiotics

• No current evidence of intra-abdominal abscess, abdominal/pelvic fistula (not diverted), gastrointestinal perforation, gastrointestinal (GI) obstruction, and/or need for drainage nasogastric or gastrostomy tube

• No clinically significant bleeding within 28 days prior to registration

• No uncontrolled hypertension, defined as systolic ≥ 160 mm Hg or diastolic ≥ 100 mm Hg

• No major surgery within 28 days of initiation of bevacizumab

• No active autoimmune disease or history of autoimmune disease that might recur, which may affect vital organ function or require immune suppressive treatment including corticosteroids. This includes, but is not limited to, patients with a history of immune related neurologic disease, multiple sclerosis, autoimmune (demyelinating) neuropathy, Guillain-Barre syndrome, myasthenia gravis; systemic autoimmune disease such as systemic lupus erythematosus (SLE), connective tissue diseases, scleroderma, inflammatory bowel disease (IBD), Crohn's, ulcerative colitis, hepatitis; and patients with a history of toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome, or phospholipid syndrome because of the risk of recurrence or exacerbation of disease

  • Patients with vitiligo, endocrine deficiencies including type I diabetes mellitus, thyroiditis managed with replacement hormones including physiologic corticosteroids are eligible
  • Topical or inhaled steroids are allowed
  • Patients with rheumatoid arthritis and other arthropathies, Sjogren's syndrome and psoriasis controlled with topical medication and patients with positive serology, such as antinuclear antibodies (ANA), and anti-thyroid antibodies should be evaluated with the presence of target organ involvement and potential need for systemic treatment but should otherwise be eligible

• No history of (non-infectious) pneumonitis that required steroids, or current pneumonitis

• No history of stem cell or solid organ transplant

• No history of allergic reaction to the study agent(s) or compounds of similar chemical or biologic composition to the study agent(s) (or any of its excipients)

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