New use for npr-a agonist

A drug combining (A) a natriuretic peptide receptor GC-A agonist, with, as (B) an anti-malignant tumor agent, a compound having anti-microtubule action, or a PD-1 pathway inhibitor [(B')]. By administering the drug at least 5 days before administering the (B) anti-malignant tumor agent, the natriuretic peptide receptor GC-A agonist effect is exhibited, and the (B) anti-malignant tumor agent can effectively reach the inside of the tumor cells via the bloodstream, thereby making the drug useful as an anti-malignant tumor treatment drug having a strong effect.