Dostarlimab, Cisplatin and Etoposide in Combination With Radiotherapy in Sandwich Sequence for Small Cell Neuroendocrine Cervical Carcinoma

Inclusion Criteria:

1. Female participants who are 20-70 years of age on the day of signing informedconsent with histologically confirmed diagnosis of Previously untreated SCNECCIB2-IV or IB1 with LVSI or IVB with oligometastasis (only in one distant organ notmore than 2 nodules which can be encompassed by RT) will be enrolled in this study.

*A female participant is eligible to participate if she is not pregnant (seeAppendix 3), not breastfeeding, and at least one of the following conditionsapplies:

1. Not a woman of childbearing potential (WOCBP) as defined in Appendix 3 OR

2. A WOCBP who agrees to participate this trial should be informed that after theprotocol treatment the ovarian function and child-bearing potential will bepermanently lost and she has to follow the contraceptive guidance in Appendix 3after enrollment through neoadjuvant chemoimmuntherapy period till externalbeam radiotherapy (EBRT) commences.

3. Have provided archival tumor tissue sample or newly obtained biopsy of a tumorlesion not previously irradiated. Formalin-fixed, paraffin embedded (FFPE) tissueblocks are preferred to slides. Newly obtained biopsies are preferred to archivaltissue. At least 5 punch biopsiesdof 3mm in diameter.

4. Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.Evaluation of ECOG is to be performed within 7 days prior to the first dose of studyintervention.

Exclusion Criteria:

1. A WOCBP who has a positive urine pregnancy test within 72 hours prior to allocation.If the urine test is positive or cannot be confirmed as negative, a serum pregnancytest will be required. Note: in the event that 72 hours have elapsed between the screening pregnancy testand the first dose of study treatment, another pregnancy test (urine or serum) mustbe performed and must be negative in order for subject to start receiving studymedication.

2. Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti PD L2 agent orwith an agent directed to another stimulatory or co-inhibitory T-cell receptor (eg,CTLA-4, OX 40, CD137).

3. Has received prior systemic anti-cancer therapy for SCNECC including investigationalagents prior to enrollment.

4. Has received prior pelvic radiotherapy.

5. Has received radical surgery for cervical cancer.

6. Has received a live vaccine or live-attenuated vaccine within 30 days prior to thefirst dose of study drug. Administration of killed vaccines is allowed.

7. Is currently participating in or has participated in a study of an investigationalagent or has used an investigational device within 4 weeks prior to the first doseof study intervention.

8. Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form ofimmunosuppressive therapy within 7 days prior to the first dose of study drug.

9. Has a known additional malignancy that is progressing or has required activetreatment within the past 3 years. Participants with basal cell carcinoma of theskin, squamous cell carcinoma of the skin or carcinoma in situ (eg, breastcarcinoma, cervical cancer in situ) that have undergone potentially curative therapyare not excluded.

10. Has known active CNS metastases and/or carcinomatous meningitis. Participants withpreviously treated brain metastases may participate provided they are radiologicallystable, i.e. without evidence of progression for at least 4 weeks by repeat imaging (note that the repeat imaging should be performed during study screening),clinically stable and without requirement of steroid treatment for at least 14 daysprior to first dose of study intervention.

11. Has severe hypersensitivity (≥Grade 3) to dostarlimab and/or any of its excipients.

12. Participant has an active autoimmune disease that has required systemic treatment inthe past 2 years (i.e., with use of disease-modifying agents, corticosteroids, orimmunosuppressive drugs). Replacement therapy (e.g., thyroxine, insulin, orphysiologic corticosteroid replacement therapy for adrenal or pituitaryinsufficiency) is not considered a form of systemic treatment.

13. Has a history of (non-infectious) pneumonitis/interstitial lung disease thatrequired steroids or has current pneumonitis/interstitial lung disease.

14. Has an active infection requiring systemic therapy.

15. Has a known history of Human Immunodeficiency Virus (HIV) infection. Note: No HIVtesting is required unless mandated by local health authority.

16. Has a known history of untreated Hepatitis B (defined as Hepatitis B surface antigen [HBsAg] reactive) or known active Hepatitis C virus infection (for those withanti-HCV+, patients who ever HCV RNA positive should undergo 8-12 weeks directacting agents (DAA) treatment and confirmed with HCV cure, defined as HCV RNAnegative at week 12 post end-of-treatment). Note: Testing for Hepatitis B andHepatitis C is required but the patient is eligible if well controlled.

17. Has a history or current evidence of any condition, therapy, or laboratoryabnormality that might confound the results of the study, interfere with theparticipant's participation for the full duration of the study, or is not in thebest interest of the participant to participate, in the opinion of the treatinginvestigator.

18. Allergy: Participant cannot have history of severe allergic and/or anaphylacticreactions to chimeric, human or humanized antibodies or fusion proteins, sensitivityto any of the study treatments or components thereof, or a history of drug or otherallergy that contraindicates their participation.

19. Has had an allogenic tissue/solid organ transplant.

20. Participant has received a live vaccine within 30 days of planned start of studytherapy. COVID-19 vaccines that do not contain live viruses are allowed. Note: mRNAand adenoviral-based COVID-19 vaccines are considered non-live.

21. Participant has cirrhosis or current unstable liver or biliary disease perinvestigator assessment defined by the presence of ascites, encephalopathy,coagulopathy, hypoalbuminemia, esophageal/gastric varices, or persistent jaundice.

Note: Stable non-cirrhotic chronic liver disease (including Gilbert's syndrome or asymptomatic gallstones) is acceptable if participant otherwise meets entry criteria.