⁃ A. Confirmed diagnosis of an ALK-positive malignancy using an analytically validated method.

⁃ B. Women of childbearing potential are eligible, provided that they meet the following criteria:

• Have a negative serum or urine pregnancy test before enrolment and;

• Agree to use one form of highly effective birth control method such as:

⁃ I. combined (oestrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation \[oral, intravaginal or transdermal\] II. progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable or implantable) III. intrauterine device (IUD) IV. intrauterine hormone-releasing system (IUS) V. bilateral tubal occlusion VI. vasectomised partner VII. sexual abstinence

⁃ Effective from the first administration of alectinib, throughout the trial and for three months after the last administration of alectinib.

⁃ C. Male patients with partners who are women of childbearing potential are eligible provided that they agree to the following, from first administration of alectinib, throughout the trial and for three months after the last administration of alectinib:

• Agree to take measures not to father children by using a barrier method of contraception (condom plus spermicide) or sexual abstinence.

• Non-vasectomised male patients with partners who are women of childbearing potential must also be willing to ensure that their partner uses a highly effective method of contraception, as in criterion B, above.

• Male patients with pregnant or lactating partners must be advised to use barrier method contraception (e.g. condom) to prevent drug exposure of the foetus or neonate.

⁃ All male patients must refrain from donating sperm for the same period.

⁃ D. Patients must be able and willing to undergo a fresh tissue biopsy.

⁃ E. Paediatric patients (patients aged \<18 years) must have a body weight ≥40kg.

⁃ F. ADULT PATIENTS (≥18 years): Adequate organ function as per haematological and biochemical indices within the ranges shown below. These measurements should be performed to confirm the patient's eligibility.

⁃ Haemoglobin (Hb): ≥90 g/L (transfusion allowed)

⁃ Absolute neutrophil count (ANC): ≥1.5 × 10\^9/L (no granulocyte colony-stimulating factor \[GCSF\] support in preceding 72 hours)

⁃ Platelet count: ≥100×10\^9/L (unsupported for 72 hours)

⁃ Bilirubin: \<1.5 × upper limit of normal (ULN) or ≤2.5 × ULN if raised due to metastases

⁃ Alanine aminotransferase (ALT) and aspartate aminotransferase (AST): ≤2.5 × ULN or ≤5 × ULN if raised due to metastases

⁃ Coagulation - prothrombin (PT) (or international normalized ratio \[INR\]) and activated partial thromboplastin clotting time (aPTT): ≤1.5 × lower limit of normal (LLN)/ULN (unless patient is on anticoagulants e.g. warfarin \[INR should be stable and within indicated therapeutic range\], or direct oral anticoagulants \[DOAC\])

⁃ Estimated glomerular filtration rate (eGFR): eGFR: ≥30 mL/min (uncorrected value)

⁃ G. PAEDIATRIC PATIENTS (\<18 years): Adequate organ function as per haematological and biochemical indices within the ranges shown below. These measurements should be performed to confirm the patient's eligibility

⁃ Hb: ≥80 g/L (transfusion allowed)

⁃ ANC: ≥1.0×10\^9/L (no GCSF support in preceding 72 hours)

⁃ Platelet count: ≥75×10\^9/L (unsupported for 72 hrs)

⁃ Bilirubin: ≤1.5 × ULN for age or ≤2.5 × ULN if raised due to metastases

⁃ ALT and AST: ≤3.0 × ULN or ≤5 × ULN if raised due to metastases

⁃ Coagulation - PT or INR and aPTT: For patients not receiving therapeutic anticoagulation: INR and aPTT ≤1.5 × ULN for age. For patients receiving therapeutic anticoagulation: stable anticoagulant regimen, e.g. warfarin (INR should be stable and within indicated therapeutic range) or DOAC.

⁃ eGFR: ≥60 mL/min/1.73m\^2