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

Alterations in the HER2 gene are involved in the development of cancer. These abnormalities are found at highly variable rates (from approximately 2% to 60%) in cancers of the lung, breast, stomach, bile ducts, salivary glands, colon, endometrium, uterus, bladder, bones, blood, etc. Zanidatamab is an anti-cancer drug that acts on cells with alterations in the HER2 gene. It is used in Europe to treat people with bile duct cancer. However, in various clinical trials, zanidatamab has shown promising activity in a few patients with different cancers that have a HER2 gene alteration. This treatment could therefore be effective in several types of cancer once this gene alteration is detected. The primary objective is to evaluate the efficacy of zanidatamab in patients with cancer in one of the following locations: endometrium, colorectal, head and neck, sarcoma or lung cancer. Efficacy will be measured by the number of patients in whom a reduction in tumour size was observed. All patients included in the study will receive zanidatamab by intravenous infusion every 3 weeks. Treatment will continue as long as there is a benefit (stabilisation or regression of the disease). During treatment, participants will visit the hospital regularly for medical consultations to: * assess and treat potential adverse effects of zanidatamab. A dose reduction may be applied to improve tolerance. * monitor disease progression using scans and/or MRI, performed every 6 weeks for the first 18 months of treatment and then every 12 weeks. After treatment is stopped (due to intolerance or disease progression), patients will be monitored according to hospital practices until the end of the trial, i.e. for 1 to 4 years, depending on when they were included in the clinical trial.