Oncothyreon Marches On With ‘Son of Stimuvax’ Cancer Vaccine
Many on Wall Street who follow Seattle-based Oncothyreon know it as the developer of Stimuvax, a product designed to stimulate the immune system to fight cancer cells. But what fewer realize is that Oncothyreon (NASDAQ: ONTY) has long envisioned a product that could trump its original Stimuvax, and it has only recently gotten the money to put this idea to the test in clinical trials.
The idea for a “son of Stimuvax” is a big part of the reason why investors recently poured $54 million into the company after what was interpreted as bad news for its lead product candidate. There are some very interesting scientific and business reasons why Oncothyreon wants to test the second-generation product, called ONT-10. It is attached to a more potent immune-boosting compound than the original, and the new drug is designed to stimulate a sort of two-pronged immune response, instead of just the T-cell reaction sparked by the original.
Both of these product candidates aim for a marker known as MUC1 that is found on a wide variety of tumor cells—including those in common malignancies of the lung, breast, ovarian, prostate, and other cancers. So if Oncothyreon can gather data that says the second-generation product offers important advantages to patients, it could be quite lucrative. That’s because not only could the product be useful for many cancer patients, but Oncothyreon owns the full commercial rights to ONT-10, and doesn’t have to split the profits with a partner, like it does on Stimuvax with Germany’s Merck KGaA.
“If Stimuvax works, we might decide to take ONT-10 all the way through on our own. We own it. We could have the follow-on product to ourselves,” says Oncothyreon CEO Bob Kirkman.
The differences between the two products could end up providing some fascinating scientific answers about what matters in the development of drugs that stimulate the immune system to fight cancer, which are sometimes called therapeutic cancer vaccines.
A little science is required to see to the differences between the two products. Stimuvax has two key components. The first is a 25-amino acid peptide segment of the MUC1 protein, which doesn’t have any sugars attached. The second piece is an immune-boosting compound known as an adjuvant—in this case a natural product from GlaxoSmithKline called MPL that is derived in bacterial cells. The combination of the MUC1 marker, known as an antigen, and the MPL adjuvant is supposed to trigger the immune system’s T-cells to recognize cancer cells as foreign invaders worthy of attack, like a flu virus.
ONT-10 also has two components, which are quite different. The backbone of the product is a longer, 43-amino acid snippet of MUC1, which does have short sugar molecules attached—which Kirkman says is thought to more closely resemble how MUC1 appears on cancer cells. Then, to make sure the immune system gets the hint, Oncothyreon has attached its own synthetic adjuvant compound that is thought to elicit a more potent immune reaction than MPL. By making those changes, Oncothyreon is hoping to trigger a broader immune system attack against cancer cells, by mobilizing both antibodies and T-cells, Kirkman says.
Olja Finn, the chair of the Department of Immunology at the University of Pittsburgh School of Medicine, said she’s encouraged by the changes the company has made to the second-generation product. She says MUC1 remains a great target for developing cancer vaccines, and she was originally “very excited” by Oncothyreon’s mid-stage clinical trial experience, which suggested that Stimuvax might be able to help extend the lives of people with Stage IIIb lung cancer.
But while Finn says she was happy to see that program advance to the final phase of clinical trials—now being conducted by Merck KGaA—she says many of her academic peers “lamented the fact that Stimuvax did not have a strong adjuvant to increase its performance in the Phase III setting.” Now that ONT-10 has been engineered to use a more potent, synthetic adjuvant or immune-boosting compound, and the rest of the drug has been engineered to more closely mimic the MUC1 peptide that appears on cancerous cells, she says it ought to spark a more robust immune reaction than the original product.
“This modification of the peptide, plus a strong adjuvant should be an improvement over Stimuvax,” Finn says. “A direct comparison in a two-arm randomized Phase II will be needed to confirm that in people.”
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