Intralymphatic administration of liposome-encapsulated drugs to mice: possibility for suppression of the growth of tumor metastases in the lymph nodes.

The antimetastatic effects of two drugs, cis-diamminedichloroplatinum(II) (DDP) and hydrocortisone (liposome-incorporated or free), were studied. The experimental models were regional and distant metastases of hepatoma A and pulmonary adenocarcinoma, which were transplanted into the footpads of A/He mice. Liposomes were prepared from phosphatidylcholine by sonic dispersion. DDP and hydrocortisone were injected sc into the region of the plantar aponeurosis of the foot with the primary tumor. This administration route was considered to be equivalent to the intralymphatic route. Evidence indicated that only liposome-incorporated DDP and hydrocortisone decreased significantly the frequency and growth rate of tumor metastases in the regional lymph nodes. The effect observed was not due to the direct action of the drugs on the primary tumors. When nonencapsulated, these drugs were ineffective. Both liposome-encapsulated and free DDP did not affect distant metastases of pulmonary adenocarcinoma. The intralymphatic administration of liposome-encapsulated antitumor agents is suggested as a method for the prophylactic treatment of tumor metastases in the lymph nodes.