A group of investigators at Penn are holding out hope that a new type of personalized tumor vaccine may break the crippling run of failures that blighted the first wave of cancer vaccines.
In a trial among 25 advanced ovarian cancer patients, researchers took autologous dendritic cells — a type of messenger cells that present antigen material to T cells — and pulsed them to whole-tumor cell lysate also from the patients. The patients then received a dose of these tumor-exposed dendritic cells every three weeks, up to six months. Almost half of the patients who could be evaluated showed a good response to the vaccine, as indicated by a big increase in the number of T cells specifically reactive to tumor material. The difference in 2-year overall survival rates between the “responder” patients and “non-responders”: 100% versus 25%.
With this approach, the team from University of Pennsylvania and the Lausanne branch of the Ludwig Institute for Cancer Research says the vaccine is primed with the unique set of mutations in an individual tumor. Given its exposure to the whole tumor, it can stimulate immune response against not just one but “hundreds or thousands” of tumor-associated targets. It is also tumor-specific, meaning the vaccine-induced T cells would be less likely to attack healthy cells.
To be sure, the study was designed primarily to assess safety and feasibility. But seeing that a patient who started with stage 4 ovarian cancer (and five prior courses of chemotherapy) remained disease-free for five years after two years of dosing, the investigators think it can prove an effective approach to fighting cancer, especially when paired up with other immunotherapies.
“This vaccine appears to be safe for patients, and elicits a broad anti-tumor immunity — we think it warrants further testing in larger clinical trials,” said lead author Janos Tanyi in a statement about the study, published in Science Translational Medicine.
Biotech after biotech has bitten the dust in pursuit of cancer vaccines using shared antigens, from Bavarian Nordic and Aduro to Sellas and Argos, which flopped badly despite deploying a personalized approach.
Yet that hasn’t stopped developers from trying.
Moderna and BioNTech are the better known players in the second wave of cancer vaccines, with enormous piles of cash for their mRNA programs. As of December 2017, the Cancer Research Institute counted 344 human studies in progress for cancer vaccines.
Patient segmentation, manufacturing and cost will likely remain key hurdles for success in this field. But this kind of early results is exactly what keeps companies hopeful.
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