Phase I Trial of CArbonic Anhydrase Inhibition in Combination with Radiochemotherapy or Radioimmunotherapy in Small Cell Lung Carcinoma

Inclusion Criteria:

• Age > or = 18 years,

• Performance Status 0 to 2,

• Patient with an histologically non-metastatic localized (or extensive SCLCsub-group) Small cell lung cancer,

• Patient who must start radiotherapy treatment combined with chemotherapy withplatinum and etoposide (localized SCLC sub-group) or Patient who received 4 cyclesof chemoimmunotherapy with platinum salts, etoposide and immunotherapy (atezolizumabor durvalumab) as the first treatment (extensive SCLC sub-group) Note: The decisionof the Multidisciplinary Consultation Team must be notified in the patient's medicalfile,

• Evaluation lesion according to the criteria RECIST 1.1 and / or according to thecriteria PERCIST 1.0,

• Women of childbearing potential must have a negative serum pregnancy test within 72hours of the first administration of the study treatment,

• If the patient is a woman of childbearing potential, she must be surgically sterileor agree to use two adequate methods of contraception throughout the duration of thestudy until 1 month after the last administration of the study treatment. Subjectsof childbearing potential are those who have not been surgically sterilized or havenot been free from menses for > 1 year, Note: Abstinence is acceptable if it is thepatient's usual and preferred form of contraception,

• If the male patient has one or more female partners of childbearing age, he / shemust agree to use an adequate method of contraception, starting at the firstadministration of the study treatment up to 1 month after the last administration ofthe treatment. of the study, Note: Abstinence is acceptable if it is the patient'susual and preferred form of contraception,

• Patient willing and able to provide written informed consent/assent for the trial,

• Patient affiliated with a health insurance system.

Exclusion Criteria:

• Patient with metastatic disease,

• History of thoracic irradiation or near / in the thoracic irradiation field,

• Patient who refuses to participate in the study or unable to agree,

• Contraindication to thoracic radiotherapy treatment: congestive heart failureunbalanced (ejection fraction <30%, clinical signs), severe respiratory failure:

• COPD grade IV according to the GOLD classification,

• Some GOLD III COPD and any patient with a respiratory defect defined as: oxygendependence and / or FEV1 <40% normal and / or, DLCO <40% predictive value and /or vital capacity <40% predictive value,

• Contraindication to acetazolamide: hypersensitivity to acetazolamide, severehepatic, renal or adrenal insufficiency, sulfonamide intolerance, history of renalcolic, allergy to wheat other than celiac disease,

• Patient currently receiving one or more treatments described in section 6.9 of theprotocol,

• History of cancer, with the exception of cancers in complete remission for more than 5 years, completely resected basal cell carcinoma of the skin or squamous cellcarcinoma of the skin that has undergone potentially curative therapy or in situcervical cancer,

• People particularly vulnerable as defined in Articles L.1121-5 to -8 of the FrenchHealthcare Code, including: person deprived of freedom by an administrative orjudicial decision, adult being the object of a legal protection measure or outside astate to express their consent, pregnant or breastfeeding women