A combination of Dynavax Technologies’ immunotherapy SD-101 and Keytruda triggered tumor-fighting responses in a third of patients with an advanced head and neck cancer, a Phase 1b/2 clinical trial showed.
The response rate was double the 15 percent seen in a Phase 3 trial that involved Keytruda alone. SD-101 was also safe, the Phase 1b/2 trial showed. The two trials’ participants had squamous cell carcinoma of the head and neck, or SCCHN.
Dynavax presented the results of the Phase 1b/2 trial (NCT02521870) in a poster session at the annual meeting of the American Association for Cancer Research in Chicago, April 14-18. The presentation was titled “Phase 1b/2, Open-Label, Multicenter Study of Intratumoral SD-101 in Combination With Pembrolizumab in Anti-PD-1 Treatment-Naïve Patients With Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma.”
“Results from our Phase 1b/2 trial of SD-101 in combination with Keytruda are promising in head and neck cancer, a condition for which patients typically have a poor prognosis,” Eddie Gray, the chief executive officer of Dynavax, said in a press release. “This is another tumor type in which SD-101, based on early data, has demonstrated encouraging activity while being well tolerated. As understanding of combination therapy matures, we believe an effective immune-stimulating agonist with an attractive tolerability profile will play a significant role in a wide range of tumors.”
SD-101 is a toll-like receptor 9 (TLR9) agonist delivered directly into tumors, where it activates the immune system.
Dyvanax is evaluating SD-101’s safety and activity in several trials. One of them, the multicenter Phase 1b/2 study, looked at SD-101 in combination with Keytruda in 18 patients with advanced SCCHN who had not received a previous anti-PD-1 therapy.
Keytruda, which is an anti-PD-1 therapy, is designed to prevent cancer cells from hiding from the immune system, improving immune responses.
The combo reduced the size of six patients’ tumors. Four other patients’ disease stopped worsening. The results translated into a response rate of 33 percent.
Importantly, the approach also led to a reduction in non-treated tumors as well. What scientists call the abscopal effect occurs when immune cells from treated tumors, which are primed to attack cancer cells, travel elsewhere in the body to attack cancer there. One patient ended up with no signs of liver tumor after this happened, researchers said.
Patients also tolerated the combo well, with researchers reporting no dose limiting toxicities. A promising finding was that the combo did not lead to more intense or more frequency adverse events than Keytruda alone. The most common events were injection site reactions and flu-like symptoms such as fever, chills and muscle pain.
Researchers also tested the combo in metastatic melanoma. Eighty-six percent of patients continued to respond to it after a median of 18 months, researchers said. The patients also tolerated it well.