A Study Comparing Savolitinib Plus Osimertinib vs Savolitinib Plus Placebo in Patients With EGFRm+ and MET Amplified Advanced NSCLC

Inclusion Criteria: * Patients must be ≥ 18 years of age at the time of signing the informed consent (≥ 20 years of age in Japan). All genders are permitted * Histologically or cytologically confirmed locally advanced or metastatic EGFRm+ NSCLC harbouring an EGFR mutation known to be associated with EGFR TKI sensitivity and that is permitted in the osimertinib national label (such as exon 19 deletion and/or L858R), which is not amenable to curative therapy. * Documented radiologic PD following treatment with osimertinib (osimertinib does not need to be the most recent therapy). * Have MET amplification as determined by central MET FISH testing on tumour specimen collected following progression on prior osimertinib treatment. * At least measurable target lesion * Patients must have received at least one but no more than 3 prior lines of therapy (including investigational therapy) in the locally advanced/metastatic setting. * Adequate haematological, liver and renal function * Eastern Cooperative Oncology Group/WHO performance status of 0 or 1 with no deterioration over the previous 2 weeks and a minimum life expectancy of 12 weeks. * Females of childbearing potential should be willing to use adequate contraceptive measures, should not be breastfeeding, and must have a negative pregnancy test. * Male patients with a female partner of childbearing potential should be willing to use barrier contraception during the study and for 6 months following discontinuation of study intervention. Patients should refrain from donating sperm from the start of dosing until 6 months after discontinuing study intervention. Exclusion Criteria: * Unresolved toxicities from any prior therapy greater than CTCAE Grade 1 at the time of starting study intervention with the exception of alopecia, haemoglobin ≥ 9 g/dL and Grade 2, prior platinum therapy related neuropathy. * As judged by the investigator, active gastrointestinal disease or other condition that will interfere significantly with the absorption, distribution, metabolism, or excretion of oral therapy. * Any of the following cardiac diseases currently or within the last 6 months: * Unstable angina pectoris * Congestive heart failure (NYHA Grade ≥ 2) * Acute myocardial infarction * Stroke or transient ischemic attack * Uncontrolled hypertension (BP ≥ 150/95 mmHg despite medical therapy). * Mean resting corrected QT interval (QTcF) \> 470 msec for women and \> 450 msec for men at Screening, obtained from 3 ECGs using the screening clinic ECG machine derived QTcF value. * Any factors that may increase the risk of QTcF prolongation or risk of arrhythmic events * Any clinically important abnormalities in rhythm, conduction or morphology of resting ECGs. * Acute coronary syndrome * Wide field radiotherapy (including therapeutic radioisotopes such as strontium 89) administered ≤ 28 days or limited field radiation for palliation ≤ 7 days prior to starting study intervention or has not recovered from side effects of such therapy. * Major surgical procedures ≤ 28 days of beginning study intervention or minor surgical procedures ≤ 7 days. No waiting is required following port-a-cath placement. * As judged by the Investigator, any evidence of severe or uncontrolled systemic diseases, including renal transplant or active bleeding diatheses, which in the investigator's opinion makes it undesirable for the patient to enter the study or which would jeopardise compliance with the CSP. * Active HBV (positive HBsAg result) or HCV. Viral testing is not required for assessment of eligibility for the study. * Known serious active infection including, but not limited to, tuberculosis, or HIV (positive HIV 1/2 antibodies). Testing is not required for assessment of eligibility for the study. * Presence of other active cancers, or history of treatment for invasive cancer, within the last 5 years. Patients with Stage I cancer who have received definitive local treatment at least 3 years previously, and are considered unlikely to recur are eligible. All patients with previously treated in situ carcinoma (ie, non-invasive) are eligible, as are patients with history of non-melanoma skin cancer. * Spinal cord compression or brain metastases unless asymptomatic, stable and not requiring steroids for at least 2 weeks prior to start of study intervention. * Past medical history of ILD, drug-induced ILD, radiation pneumonitis, which required steroid treatment, or any evidence of clinically active ILD. * Prior or current treatment with a 3rd generation EGFR-TKI other than osimertinib. * Prior or current treatment with savolitinib or another MET inhibitor (for example, foretinib, crizotinib, cabozantinib, onartuzumab, capmatinib). * Patients who have received ≥ 4 lines of systemic therapy for NSCLC * Any cytotoxic chemotherapy, investigational agents or other anti cancer drugs for the treatment of advanced NSCLC from a previous treatment regimen or clinical study within 14 days prior to the first dose of study intervention with the exception of monotherapy osimertinib which may continue uninterrupted during screening. * Patients currently receiving (or unable to stop use prior to receiving the first dose of study intervention) medications or herbal supplements known to be strong inducers of CYP3A4 or strong inhibitors of CYP1A2, or CYP3A4 substrates which have a narrow therapeutic range within 2 weeks of the first dose of study intervention (3 weeks for St John's Wort) will be excluded. All patients must try to avoid concomitant use of any medications, herbal supplements and/or ingestion of foods with known inducer effects on CYP3A4 during the study and for 3 months later the last dose intake. * Participation in another clinical study with a cytotoxic, investigational product, or other anti cancer drug for the treatment of advanced NSCLC if received study intervention from that study within 14 days of the first dose of study intervention. * Known hypersensitivity to the active or inactive excipients of osimertinib or savolitinib or drugs with a similar chemical structure or class.