Clinical Trial Evaluating the Activity of Zanidatamab for the Treatment of Patients With Solid Tumors With an Alteration of the HER2 Gene.

Inclusion Criteria: 1. Histologically or cytologically confirmed endometrial, colorectal, head \& neck, non-small cell lung cancer (NSCLC), or sarcoma 2. Patient with progressive, unresectable and/or advanced or metastatic disease harboring a locally performed, centrally reviewed HER2-overexpressing (IHC 3+ exclusively) for endometrial, colorectal, head \& neck cancers, or sarcoma or a HER2 activating mutation for NSCLC, determined on tissue (see Section 7.1.2 of the protocol) 3. Age ≥ 18 years at inclusion 4. Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 2 5. Patient who progressed at least after 1 line of therapy, for whom there is no other standard therapeutic option available 6. Patient with a HER2 alteration covered by a standard marketed indication for any HER2 targeting therapy should be included after standard anti-HER2 strategy has been exhausted. 7. Estimated life expectancy \>3 months 8. Measurable disease according to RECIST1.1, whatever the disease location. Tumor lesions located in a previously irradiated area, or in an area subjected to other loco-regional therapy, are considered measurable if progression has been clearly demonstrated in the lesion 9. Adequate bone marrow function: absolute neutrophil count (ANC) ≥1.5 × 10⁹/L, platelet count ≥75 × 10⁹/L, and haemoglobin ≥9 g/dL. Transfusion is allowed with a 2-week washout period before treatment initiation 10. Adequate liver function: total bilirubin level ≤1.5 × the upper limit of normal (ULN) range (total bilirubin ≤3.0 ULN when the patient has documented Gilbert syndrome or liver metastasis), and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels ≤2.5 × ULN (AST and ALT ≤5 ULN when documented tumor liver involvement) 11. Adequate cardiac function: left ventricular ejection fraction (LVEF) ≥ 50% at baseline as determined by either echocardiogram (ECHO) or multigated acquisition (MUGA) scan within 14 days before inclusion 12. Normal prothrombin time (PT) \>70% and partial thromboplastin time (PTT), except for patient who uses anticoagulants 13. Adequate renal function: estimated serum creatinine clearance ≥ 30 mL/min according to the Cockcroft-Gault formula 14. Man, and woman of childbearing potential must agree to use highly effective contraception for the duration of trial participation and as required after completing study treatment (refer to Table 6 in the protocol). Man must also agree to not donate sperm and women must agree to not donate oocytes during the specified period 15. Woman of childbearing potential must have a negative serum pregnancy test performed within 3 days before the date of treatment initiation 16. Availability of a suitable archived FFPE sample of primary or metastatic tumor tissue (archived FFPE is \<2 years old (desirable), maximum 5 years (accepted), buffered formalin fixed only. Fine-needle aspiration (cytology samples) and biopsies from sites of bone metastases are not acceptable) or patient accepts an optional biopsy under study 17. Willing and able to comply with the protocol for the duration of the study including scheduled visits, treatment plan, laboratory tests, specimen sampling for research, and other study procedures 18. Affiliated to a social security system 19. Patient must have signed a written informed consent form prior to any trial specific procedures. When the patient is physically unable to give their written consent, a trusted person of their choice, independent from the investigator or the sponsor, can confirm in signing the patient's consent. Exclusion Criteria: 1. Patient, in the judgment of the investigator, who should be included in another recruiting study assessing an anti-HER2 therapy (including zanidatamab) 2. Patient who received prior treatment with HER2-directed therapy unless marketed for the study cohort indication. 3. Other primary malignancies within 3 years with the exception of adequately treated cone-biopsied in situ carcinoma of the cervix uteri and basal or squamous cell carcinoma of the skin. Cancer survivor, who has undergone potentially curative therapy for a prior malignancy, has no evidence of that disease for 4 years or more and is deemed at negligible risk for recurrence, is eligible for the trial 4. Any autoimmune, connective tissue or inflammatory disorder with pulmonary involvement not related to lung metastases (e.g. rheumatoid arthritis, Sjögren's syndrome, sarcoidosis) 5. Prior pneumonectomy 6. Patient with any condition or any evidence of severe or uncontrolled systemic diseases (e.g. active bleeding diatheses, active infection, or psychiatric illness) which in the investigator's opinion makes it undesirable for the patient to participate in the study or which would jeopardize compliance with the protocol. Screening for chronic conditions is not required for eligibility 7. History of myocardial infarction or unstable angina within 6 months prior to enrolment, troponin levels consistent with myocardial infarction, or clinically significant cardiac disease, such as ventricular arrhythmia requiring therapy, uncontrolled hypertension, or any history of symptomatic congestive heart failure 8. Evidence of spinal cord compression or brain metastases, defined as being clinically active and symptomatic, or requiring therapy with corticosteroids or anticonvulsants to control associated symptoms. Patient with clinically inactive or treated brain metastases who are asymptomatic (i.e. without neurologic signs or symptoms and do not require treatment with corticosteroids or anticonvulsants) may be included in the study. Patient must have a stable neurologic status and no evidence of radiographic progression for at least 2 weeks prior to first zanidatamab dosing 9. Patient with evidence of any leptomeningeal disease. If leptomeningeal disease has been reported radiographically on baseline magnetic resonance imaging (MRI), but is not suspected clinically by the investigator, the subject must be free of neur