Testing the Addition of An Anti-cancer Drug, M3814 (Peposertib), to the Usual Radiation-Based Treatment (Lutetium Lu 177 Dotatate) for Pancreatic Neuroendocrine Tumors

Patients must have histologically or cytologically confirmed well-differentiated neuroendocrine tumor with positive dotatate scan (gallium 68 or copper 64) (as determined by the site principal investigator \[PI\]) within 6 months before enrollment. Lesions on the dotatate scan (gallium 68 or copper 64) are considered positive if the maximum standard uptake value (SUVmax) is \> 2 times the mean standard uptake value (SUVmean) of normal liver parenchyma. Patients must have the gallium 68 or copper 64 dotatate scans available to send for central review before enrollment

Patients must have measurable progressive disease based on RECIST criteria, version 1.1, evidenced with CT/MRI scans obtained within 12 months before enrollment

Failure of at least one prior systemic cancer treatment with somatostatin analogs

No prior exposure to peptide receptor radionuclide therapy

Age \>= 18 years

Eastern Cooperative Oncology Group (ECOG) performance status =\< 2 (Karnofsky \>= 60%)

White blood cell count \>= 2,000/mcL

Absolute neutrophil count \>= 1,000/mcL

Platelets \>= 75,000/mcL

Hemoglobin \>= 8.0 g/dL

Total bilirubin =\< 1.5 x institutional upper limit of normal (ULN)

Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase \[SGOT\])/alanine aminotransferase (ALT) (serum glutamic pyruvic transaminase \[SGPT\]) =\< 3 x institutional ULN

Alkaline phosphatase =\< 3 x institutional ULN

Glomerular filtration rate (GFR) \>= 50 mL/min/1.73 m\^2 (per the Cockcroft-Gault \[C-G\])

Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial

For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated

Patients with a prior or concurrent malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial

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 2B or better

Patients must have recovered from adverse events of previously administered therapeutic agents to grade 2 or less toxicity according to Common Terminology Criteria for Adverse Events (CTCAE) 5.0

Pregnancy Precaution: Women should avoid pregnancy for seven months after the date of their last treatment with lutetium Lu 177 dotatate. Men should avoid fathering a child for 4 months after the last dose of Lutetium Lu 177 dotatate. It is noteworthy that beta-human chorionic gonadotropin (HCG) may be secreted by a small percentage of neuroendocrine tumor (NET)s, such that, in addition to being a pregnancy marker, it also is a tumor marker. Consequently, NET female patients with positive beta-HCG (\> 5 mIU/mL) at baseline can be eligible to enter the study and receive treatment if pregnancy can be excluded by lack of expected doubling of beta-HCG and negative pelvic ultrasound. Normally, in pregnant subjects beta-HCG doubles every 2 days during the first 4 weeks of pregnancy and every 3.5 days by Weeks 6 to 7. Women of childbearing potential include any female who has experienced menarche and who has not undergone successful surgical sterilization (hysterectomy, bilateral tubal ligation, or bilateral ovariectomy) or is not postmenopausal (defined as amenorrhea \> 12 consecutive months, and for women on hormone replacement therapy, only with a documented plasma follicle-stimulating hormone \[FSH\] level \> 35 mIU/mL). Even women who are using oral, implanted, or injected contraceptive hormones, an intrauterine device (IUD), or barrier methods (diaphragm, condoms, spermicidal) to prevent pregnancy, are practicing abstinence, or where the partner is sterile (e.g., vasectomy) should be considered to be of childbearing potential. Postmenopausal women who have fertilized eggs implanted are also considered to be of childbearing potential. Acceptable methods of contraception may include total abstinence at the discretion of the Investigator in cases where the age, career, lifestyle, or sexual orientation of the patient ensures compliance. Periodic abstinence (e.g., calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. Reliable contraception (hormonal or barrier method of birth control; abstinence) should be maintained throughout the study and for 7 months after study treatment discontinuation, for women, and for 4 months for men. All women of childbearing potential and male partners must use a double-barrier method of birth control or practice continuous abstinence from heterosexual contact throughout the study and for seven months after the end of the last treatment for women, and four months for men

Ability to understand and the willingness to sign a written informed consent document. Participants with impaired decision-making capacity (IDMC) who have a legally-authorized representative (LAR) and/or family member available will also be eligible.

What this study is about