This is a Phase 1 study to evaluate the safety, tolerability, and pharmacokinetics of DS-6051b in Japanese subjects with advanced solid malignant tumors harboring either a ROS1 or NTRK fusion gene.

This study is single arm study with DS-6051b in approximately 9 subjects with advanced solid malignant tumors harboring either a ROS1 or NTRK fusion gene. Safety and tolerability, pharmacokinetics (PK), maximum tolerated dose/recommended phase 2 dose (MTD/RP2D) and preliminary efficacy of DS-6051b will be evaluated.

Inclusion Criteria:

• Advanced solid malignant tumors that are refractory to standard therapy or for which no standard therapy is available.
• An Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-1.

Exclusion Criteria:

• Previously had or currently has any of the following diseases:

Cardiac failure (NYHA Functional Classification ≥ Class III), myocardial infarction, cerebral infarction, unstable angina, arrhythmia requiring treatment, coronary/peripheral artery disease, pulmonary thrombosis, uncontrolled deep vein thrombosis, clinically severe thromboembolic event, or autoimmune disease requiring treatment.

• Previously had or currently has clinically severe pulmonary disease (eg, interstitial pneumonia, pneumonitis, pulmonary fibrosis, radiation pneumonia).
• Severe or uncontrolled concomitant disease.
• Clinically active brain metastases or central nervous system tumor requiring steroid or anticonvulsant treatment.

De-identified individual participant data (IPD) and applicable supporting clinical trial documents may be available upon request at https://vivli.org/. In cases where clinical trial data and supporting documents are provided pursuant to our company policies and procedures, Daiichi Sankyo will continue to protect the privacy of our clinical trial participants. Details on data sharing criteria and the procedure for requesting access can be found at this web address: https://vivli.org/ourmember/daiichi-sankyo/

Studies for which the medicine and indication have received European Union (EU) and United States (US), and/or Japan (JP) marketing approval on or after 01 January 2014 or by the US or EU or JP Health Authorities when regulatory submissions in all regions are not planned and after the primary study results have been accepted for publication.

Formal request from qualified scientific and medical researchers on IPD and clinical study documents from clinical trials supporting products submitted and licensed in the United States, the European Union and/or Japan from 01 January 2014 and beyond for the purpose of conducting legitimate research. This must be consistent with the principle of safeguarding study participants' privacy and consistent with provision of informed consent.