technique was developed to isolate these tumor infiltrating 
lymphocytes. Tumor infiltrating lymphocytes (TIL) can be grown 
by culturing single cell suspensions from tumors in a medium 
containing IL-2. In 2-3 weeks, a pure culture of lymphocytes 
derived from the original suspension remains, having outgrown the 
tumor cells. 
Dr. Rosenberg noted that in experiments published in Science 
utilizing an experimental animal model, the therapeutic 
properties of such TIL were 100 times more potent than LAK cells 
and were shown to produce a 100% reduction in metastases. These 
results became the basis for considering trials in humans. 
Experiments were then undertaken to grow TIL from patients with 
metastatic cancer. It was found that they could be grown from 
virtually any kind of tumor, and that they had a unique 
reactivity with the patient's cancer but not with the patient's 
normal cells. At the same time, these TIL had no reactivity with 
other patient's cancers. The experiments showed that TIL from a 
patient lysed his tumor efficiently but did not lyse his 
fibroblasts, B cells, normal lymphoid cell lines or any other 
allogeneic tumor, representing the best evidence available to 
date that patients with growing cancers do mount immunologic 
reactions against their own tumors. 
With this background, the FDA granted permission to begin a trial 
with TIL, a report of which has been submitted for publication to 
The New England Journal of Medicine and will probably appear 
soon. Dr. Rosenberg summarized the results by stating that of 
the first 20 melanoma patients treated, 15 of whom had not 
previously received TIL therapy, there was a 50 percent reduction 
in tumor mass in 9 of the first 15 patients, and one patient had 
experienced a complete regression. The majority of these 
patients had only received a single course of therapy, but 
multiple course therapy has been approved recently by the FDA. 
Dr. Rosenberg said that 5 patients who had previously failed 
treatment with LAK cells were treated in an effort to gain 
information about TIL potency and 2 of these patients had good 
objective regressions, an indication of increased efficiency of 
this approach. 
Dr. Rosenberg presented individual case information on three 
patients and summarized that the experiments show that it is 
possible to utilize the immune system to mediate regression of 
growing cancers, but that the treatment is not perfect in view of 
the fact that less than half of patients respond. Further, there 
are toxicities associated with the treatment and much more must 
be learned about its mechanisms of action. One major goal is to 
identify correlates between classes of lymphoid cells that cause 
regression and their in vivo activities. Further information 
concerning long-term survival of human TIL is also needed. 
Dr. Rosenberg also noted that there was no existing technique 
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