Evidence of Resistance to Tumor Graft in Early Stages of Induced Oncolysis,

Summary Eight to sixteen successive intratumoral injections at two to three day intervals of material extracted from fresh tumor tissue by means of alcohol, resulted in complete recovery from tumor growth of seventy of the tumor bearing rats treated in this manner. All of the treated rats (100%) implanted with a challenge graft after they had received six intratumoral injections of an alcoholic extract of tumor tissue, had by this time developed sufficient tumor resistance to protect them from the growth of the second graft of tumor tissue, and seventy per cent of the treated rats challenged after they had received four intratumoral injections also showed evidence of tumor resistance. One to two months after the challenge grafts had failed to grow, the rats were again engrafted with viable tumor tissue. These grafts also failed to grow, showing that the hosts had developed tumor immunity.