Immunotherapy Weekly
Publisher: CW Henderson
Issue: December 11, 2002
Page: 3

Melanoma
T-cell clones shrink tumors

2002 DEC 11 - (NewsRx.com) -- A preliminary clinical trial suggests
that armies of T cells generated in the lab can be injected into
patients to halt the spread of cancerous tumors.

The study, conducted by Dr. Cassian Yee, a researcher at the Fred
Hutchinson Cancer Research Center, involved 10 people diagnosed with
advanced melanoma. For each patient immune system cells able to
identify and target melanoma were extracted and cloned. The cloned
cells were expanded in the lab and reinjected into the patient. The
results of the study showed that in five patients tumors stopped
growing for up to one year and in three of the patients the tumors
appeared to shrink.

"While we did not expect to cure the cancers, the technique appears
to benefit patients by curbing the spread of their tumors," said Yee.

One strategy for treating cancer is to sensitize the immune system to
the presence of tumors so it can attack the cancerous cells.
Vaccinating patients with proteins present on the cancerous cells
could kick the immune system into action. Instead of relying on the
immune system to manufacture a defense, however, Cassian Yee and
colleagues tried supplying ready-made soldiers. In the lab, the
authors grew T cells, those cells that destroy invaders or aberrant
cells. To insure that the T cells found their target, the authors
trained them on their quarry, stimulating the cells with a protein
found on metastatic melanoma cells.

The authors then injected these designer T cells into 10 patients
over the course of 12 weeks. The results, reported in the Proceedings
of the National Academy of Sciences USA article #6000, indicate that
the T cells clones were able to home in on the tumors, which
regressed slightly or stabilized in 8 of the 10 patients, for an
average period of 11 months. In addition to T cells, the injections
contained IL-2, a chemical that stimulates the T cells to replicate,
resupplying the troops.

Although IL-2 can be toxic in high doses, the patients showed little
reaction to the low dose of IL-2 used (Yee C, Thompson JA, Byrd SR,
et al., Adoptive T cell therapy using antigen-specific CD8+ T cell
clones for the treatment of patients with metastic melanoma: in vivo
persistence, migration and antitumor effect of transferred T cells.
Proc Natl Acad Sci USA, November 11, 2002 (online)).