The present disclosure relates to methods for treating cancer by intrapulmonary administration of a polynucleotide Toll-like receptor 9 agonist. The methods of the present disclosure are suitable for treating primary cancer of the lung, as well as metastatic cancer to the lung and extra pulmonary cancers thereof. Additionally, the present disclosure provides polynucleotide Toll-like receptor 9 agonists with immune stimulatory and toxicity profiles suitable for intrapulmonary administration.