Inclusion criteria

          -  Histologically or cytologically confirmed diagnosis of an advanced, unresectable
             and/or metastatic malignant solid tumor and indication for treatment

          -  Patient must have exhausted established treatment options known to prolong survival
             for the malignant disease, or is not eligible for established treatment options.

          -  Medically fit and willing to undergo all mandatory trial procedures.

          -  At least one tumor lesion which is suitable for injection (Screening/initial
             administration), appropriate for the allocated treatment arm, and measurable.

          -  At least 1 discrete lesion, in addition to the lesion proposed for injection, which is
             amenable to biopsy and is not located in the brain, mediastinum or pancreas.

          -  Adequate organ function or bone marrow reserve

          -  Further inclusion criteria apply

        Exclusion criteria:

          -  Any investigational or antitumour treatment (including antibodies targeting Programmed
             Cell Death-1 (PD1) - or programmed Death-Ligand 1 (PDL1)) within 4 weeks or 5
             half-life periods (whichever is shorter) prior to the initial administration of BI
             1387446 or BI 754091.

          -  Persistent toxicity from previous treatments (including Immune-related Adverse Events
             (irAEs)) that has not resolved to ≤ Grade 1, except for alopecia, xerostomia, and
             immunotherapy related endocrinopathies which may be included if clinically stable on
             hormone supplements or antidiabetic drugs as per Investigator judgement

          -  History or evidence of active, non-treatment related autoimmune disease, except for
             endocrinopathies which may be included if clinically stable on hormone supplements or
             antidiabetic drugs.

          -  History or evidence of pneumonitis related to prior immunotherapy

          -  Immunosuppressive corticosteroid doses (>10 mg prednisone daily or equivalent) within
             2 weeks prior to the first dose of BI 1387446 or BI 754091.

          -  The tumor at the projected injection site has a high risk for local complications,
             e.g. bleeding related to encasement/infiltration of major blood vessels or contact
             with liver capsule, compression of vital structures in case of swelling of injected
             lesion, in the opinion of the Investigator.

          -  Active infection requiring systemic therapy at the start of treatment in the trial,
             including active viral hepatitis infection or active tuberculosis infection.

          -  Cardiac insufficiency New York Heart Association (NYHA) III or IV

          -  Left ventricular ejection fraction < 50% measured by echocardiography or Multigated
             Acquisition (MUGA) scan

          -  Mean resting corrected QT interval (QTc) >470 msec

          -  Arm C: Patients on therapeutic doses of anticoagulants.

          -  Further exclusion criteria apply