This is a study for people with advanced cancer for whom previous treatment was not successful. Adults aged 18 and over with advanced cancer with HER2 alterations can join the study. The purpose of this study is to find out whether a medicine called zongertinib helps people with advanced cancers with HER2 alterations. HER2 alterations can cause cancer. Zongertinib inhibits HER2.

Participants are put into groups based on the type of advanced cancer they have, the type of HER2 alterations they have, and the dose of zongertinib they receive. Depending on the group they are in, participants take 1 of 2 different doses of zongertinib each day. Participants can continue the treatment as long as they benefit from it and can tolerate it.

Participants visit the study site regularly. During many of the visits, the doctors check the size of the tumour and whether it has spread to other parts of the body. During all the visits, the doctors check participants' health and take note of any unwanted effects.

inclusion criteria:

• Signed and dated written informed consent in accordance with International Council for Harmonisation-Good Clinical Practice (ICH-GCP) and local legislation prior to admission to the trial.

• Patients ≥18 years old or over the legal age of consent in countries where that is greater than 18 years at the time of signature of the Informed consent form (ICF).

• Documented (previously established by local testing) Human epidermal growth factor receptor 2 (HER2) status of:

  • HER2 amplification
  • Known activating HER2 mutations

• Availability and willingness to provide a sample of archival formalin-fixed paraffin embedded (FFPE) tumour tissue material

• Patient with histologically or cytologically confirmed locally advanced unresectable or metastatic solid tumour who has had at least one prior line of therapy for metastatic disease. In the opinion of the Investigator, patients must be unlikely to tolerate or derive clinically meaningful benefit from further standard of care therapy known to prolong survival.

Further inclusion criteria apply.

exclusion criteria:

• Diagnosis of HER2 mutant Non-small cell lung cancer (NSCLC)

• Previous or concomitant malignancies other than the 1 treated in this trial within the previous 3 years except:

  • effectively treated non-melanoma skin cancers
  • effectively treated carcinoma in situ of the cervix
  • effectively treated ductal carcinoma in situ of the breast
  • localised prostate cancer on watchful waiting or active surveillance
  • other effectively treated malignancy that is considered cured by local treatment.

• Patients who must or wish to continue the intake of restricted medications or any drug considered likely to interfere with the safe conduct of the trial

• Not completely recovered from major surgery (major according to the investigator's assessment) performed prior to screening or planned within 6 months after screening, e.g. hip replacement Further exclusion criteria apply.

Once the criteria in section 'time frame' are fulfilled, researchers can use the following link hhttps://www.clinicalstudies.boehringer-ingelheim.com/msw/datasharing to request access to the clinical study documents regarding this study, and upon a signed "Document Sharing Agreement". Furthermore, researchers can request access to the clinical study data, for this and other listed studies, after the submission of a research proposal and according to the terms outlined in the website.

One year after the approval has been granted by major Regulatory Authorities and after the primary manuscript has been accepted for publication, or after termination of the development program.

For study documents -upon signing of a 'Document Sharing Agreement'.For study data -1. after the submission and approval of the research proposal (checks will be performed by the sponsor and/or the independent review panel, including checking that the planned analysis does not compete with sponsor's publication plan); 2. and upon signing of a legal agreement.