Five of the eight patients did see their melanoma recur. In two cases, Ott said, the recurrences happened early, and the patients were given drugs called checkpoint inhibitors.
Checkpoint inhibitors, like the cancer vaccine, fall under the umbrella of “immunotherapy” — treatments that enlist the immune system to help destroy tumor cells.
The drugs work by removing the “brakes” from T cells’ ability to respond to tumor cells. And they are already a standard part of care for melanoma patients like those in this study.
When the two study patients with early recurrences started on checkpoint inhibitors, they quickly responded, showing a complete resolution of their tumors. According to Ott, that suggests the vaccine might have worked in concert with the checkpoint inhibitors, generating a T cell response that the medications then freed up.
The only way to know whether the vaccine improves patients’ outlook, however, is through a clinical trial, said Dr. Ahmad Tarhini, a melanoma specialist and researcher who was not involved in the study.
That, he explained, would mean randomly assigning melanoma patients to either have the vaccine added to standard treatment with checkpoint inhibitors, or have standard treatment alone.
Based on these patients, the vaccine by itself might not be enough to prevent melanoma recurrences, said Tarhini, a senior member of the departments of cutaneous oncology and immunology at Moffitt Cancer Center in Tampa, Fla.
That said, Tarhini called the current findings an important step forward in creating customized cancer vaccines.
“As a proof-of-principle, this is successful,” Tarhini said. “The vaccine can induce a durable immune system response that is well-tolerated.”
In theory, Ott said, personalized vaccines could be used for a range of cancers. NeoVax is being studied as an additional therapy for other cancers, including later-stage ovarian and kidney cancers.
If the approach eventually proves to keep cancer recurrences at bay, Ott noted, there will be real-world issues — namely, the time and money it takes to create personalized vaccines.
Dana-Farber, the primary site for the NeoVax research, says it holds “a proprietary and financial interest in the personalized neoantigen vaccine.”