Summary

This phase II trial compares tuvusertib in combination with avelumab to tuvusertib alone to determine whether the combination therapy will lengthen the time before the cancer starts getting worse in patients with Merkel cell cancer that has not responded to previous treatment (refractory). Tuvusertib is a drug that inhibits an enzyme called ataxia telangiectasia and Rad3 related (ATR) kinase, which is an enzyme that plays a role in repair of damaged deoxyribonucleic acid (DNA) as well as tumor cell replication and survival. It may lead to tumor cell death by inhibiting ATR kinase activity. Immunotherapy with monoclonal antibodies, such as avelumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving tuvusertib in combination with avelumab may lengthen the time before Merkel cell cancer starts getting worse compared to giving avelumab alone.

Objectives

PRIMARY OBJECTIVE:
I. To compare the potential efficacy, using progression free survival (PFS), of ATR inhibition alone to ATR inhibition plus anti-PD-(L)1 therapy through a randomized clinical trial for patients with advanced Merkel cell carcinoma (MCC) who have progressed on anti-PD(L)1 therapy.

SECONDARY OBJECTIVES:
I. To compare the clinical activity of ATR inhibition alone to that in combination with avelumab through a randomized clinical trial for patients with advanced MCC that has progressed after PD-1 pathway blockade.
II. To identify gene expression-based immunologic (replication stress / neuroendocrine [NE] differentiation) signatures predictive of response to ATR inhibition in advanced immunotherapy-refractory MCC tumors through ribonucleic acid sequencing (RNAseq).

EXPLORATORY OBJECTIVES:
I. To examine the association of various biomarkers with the clinical activity of ATR inhibition alone or in combination with PD-(L)1 pathway blockade.

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM 1: Patients receive tuvusertib orally (PO) once daily (QD) on days 1-14 of each cycle. Cycles repeat every 21 days in the absence of disease progression or unacceptable toxicity. Patients also undergo computed tomography (CT), positron emission tomography (PET)/CT, or magnetic resonance imaging (MRI), biopsy, and collection of blood and stool/rectal swabs at screening and on study. Patients with documented progression may cross over to Arm 2.

ARM 2: Patients receive tuvusertib PO QD on days 1-14 of each cycle and avelumab intravenously (IV) over 60 minutes on day 1 of each cycle. Cycles repeat every 21 days in the absence of disease progression or unacceptable toxicity. Patients also undergo CT, PET/CT, or MRI, biopsy, and collection of blood and stool at screening and on study.

After completion of study treatment, patients are followed up at 30 days and then every 6 months for 2 years.

Eligibility

1. Patients must have a history of pathologically confirmed locally advanced/unresectable Merkel cell carcinoma or metastatic Merkel cell carcinoma
2. Patients must have evaluable disease per Response Evaluation Criteria in Solid Tumors (RECIST) version (v)1.1
3. Patients must have had prior treatment with anti-PD-1 or anti-PD-L-1 antibody (e.g., pembrolizumab, avelumab, etc.) and have experienced progressive disease during treatment or within 120 days from the last dose of anti-PD-(L)1 therapy. Anti-PD-(L)1 therapy administered in combination with other agent(s) including ipilimumab is also allowed as prior therapy, if patients experienced progressive disease during treatment or within 120 days from the last dose of anti-PD-(L)1 therapy
4. Age >= 18 years. Because no dosing or adverse event data are currently available on the use of M1774 in combination with avelumab in patients < 18 years of age, children are excluded from this study
5. Eastern Cooperative Oncology Group (ECOG) performance status =< 2 (Karnofsky >= 60%)
6. Absolute neutrophil count >= 1,000/mcL
7. Platelets >= 100,000/mcL
8. Total bilirubin =< institutional upper limit of normal (ULN) or = 1.5 x ULN for subjects with Gilbert’s disease
9. Aspartate aminotransferase (AST)(serum glutamic-oxaloacetic transaminase [SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) =< 3 x institutional ULN
10. Creatinine =< institutional ULN
11. Estimated glomerular filtration rate (eGFR) >= 60 mL/min/1.73 m^2
12. Hemoglobin >= 9.0 g/dL
13. Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial
14. For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated
15. Patients with a history of hepatitis C virus (HCV) infection must have been treated and cured. For patients with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load
16. Patients with treated brain metastases are eligible if follow-up brain imaging during screening shows no evidence of progressive brain metastases and it has been at least 4 weeks since central nervous system (CNS) directed therapy
17. 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
18. 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
19. The effects of M1774 on the developing human fetus are unknown. For this reason and because ATR inhibitor agents as well as other therapeutic agents used in this trial are known to be teratogenic, women of child-bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and, for the duration of study participation, and 6 months after completion of M1774 and avelumab administration. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 3 months after completion of M1774 and avelumab administration
20. Ability to understand and the willingness to sign a written informed consent document. Legally authorized representatives may sign and give informed consent on behalf of study participants

Treatment Sites in Georgia