Making a product

In 1997, Srivastava prepared doses of an hsp from mouse tumors. When given back to the donor mice, the hsp (with peptides still attached) reduced by ten-fold the number of metastases – the new growths derived from a large tumor. If the large mass was removed first, otherwise untreated mice died of micrometastases, but additional hsp treatment resulted in symptom-free survival in 80% of the mice.

Before Antigenics could start treating people they needed an efficient means of producing a personalized therapy. In the current procedure, a patient’s tumor sample is rushed by courier to Antigenics, where it is passed, in a ten-hour procedure, through a blender, a centrifuge, and two fractionating columns. The final preparation of hsps and associated peptides is 80-95% pure. This preparation is then administered to the patient over the following weeks.

From tumor to treatment.

Immunizing with such a poorly defined set of peptides raises concerns about reproducibility. "That has regulatory implications," says Biomira’s Longenecker. "Big pharma won’t touch that." Srivastava says that regulatory agencies "have not encountered a procedure like this but they have been extremely helpful and cooperative. They have been extremely understanding about the novelty of it."

continue...

Vaccinating against cancer