DCP-001, the lead cancer vaccine candidate by DCprime, safely elicited a tumor-specific immune response in patients with acute myeloid leukemia (AML), who still showed signs of residual disease despite having entered remission, according to interim data from an ongoing Phase 2 trial.
These findings suggest that DCP-001 has the potential to keep AML under control and enable these patients to remain in remission for long periods of time, the company stated. Additional trial data is expected next year.
“Provided with the right tools, the possibility to prolong remission for a number of patients has wider medical implications and could be transformative for future cancer care,” Jeroen Rovers, MD, PhD, chief medical officer of DCprime, said in a press release.
“The study results will continue to mature over the course of 2021 as we are progressing to treat patients in the higher dose group and aim to have top-line data available in [late] 2021,” he added.
Trial findings were presented by Arjan van de Loosdrecht, MD, PhD, the trial’s lead investigator, in an oral presentation, titled “Conversion from MRD Positive to Negative Status in AML Patients in CR1 after Treatment with an Allogeneic Leukemia-Derived Dendritic Cell Vaccine,” at the 62nd American Society of Hematology Annual Meeting and Exposition, held virtually Dec. 5–8.
DCP-001 is a cell-based vaccine designed to prevent disease relapse in patients with blood cancers who are at a high risk of having their cancer return. The vaccine has been created by converting DCOne, the company’s proprietary leukemic cell line, into mature dendritic cells that are highly immunogenic (able to trigger an immune response) due to their ability to present certain molecules that activate other immune cells.
In an earlier Phase 1 trial, the experimental vaccine was found to be safe and well-tolerated, and capable of triggering robust immune responses.
The safety and efficacy of DCP-001 are currently being investigated in an ongoing Phase 2 trial, called ADVANCE II (NCT03697707). The study aims to enroll up to 20 AML patients who, despite being in remission, still show signs of residual disease (confirmed measurable residual disease, or MRD positivity).
During the study, participants will receive an initial vaccination regimen consisting of four immunizations containing one of two doses — 25×106 (low) or 50×106 (high) cells per vaccination — of DCP-001. This will be followed by two booster vaccinations, each containing 10×106 cells, at 14 and 18 weeks after the start of treatment.
The trial is still recruiting participants in the higher DCP-001 dose group across several European countries; more information can be found here.
The study’s main goals include assessing the safety and tolerability of the two vaccine doses, as well as their ability to trigger an immune response, and their effects on patients’ MRD status. Additional study goals include assessing the vaccine’s ability to elicit an immune response against specific tumor molecules.
Interim data from ADVANCE II presented at the annual meeting showed DCP-001 was not only safe and well-tolerated, but also able to trigger a tumor-specific immune response.
Safety analyses included data from 15 patients, ages 40–76, who were enrolled and dosed in the study so far. These included a group of 10 patients who received the lower dose of DCP-001, as well as the first participants to be treated with the higher dose.
These findings indicated that all vaccinations were well-tolerated, with most immunizations causing local temporary side effects, such as redness, swelling, and warmth, that were considered mild or moderate in severity.
MRD status was assessed in seven patients. From these, two switched from a MRD-positive to a MRD-negative status after receiving the first vaccination regimen (until week 14) and continued showing no signs of residual disease up until week 32. The remaining five patients remained MRD-positive until week 32, despite continuing in clinical remission.
Three patients saw their cancer return and progress before their vaccination regimen was completed and their MRD status was determined. The other five patients have not yet completed their treatment and are still awaiting their first MRD evaluation. However, for the time being, all are in remission.
“The interim results of the study reaffirm that the usage of this novel relapse vaccine is very safe and easy to use in patients,” said van de Loosdrecht, who is also a professor at the Amsterdam University Medical Center. “Initial data on immunological responses seem to indicate that it triggers an immune response, which is also seen in patients through local redness and swelling at the injection site.”
“It is very promising to see that in the small set of patients treated to date we already observed two cases of MRD conversion, making these patients MRD-negative and thus providing hope for durable disease control,” van de Loosdrecht said.
Interim data also included an immune response analysis, which was performed in a subset of five patients, including the two who saw their MRD status shift early on following vaccination.
This analysis showed that in this small group of patients, DCP-001 increased the number of immune T-cells that were primed to attack malignant cancer cells containing a series of tumor-specific molecules. Importantly, this increased number of primed T-cells was observed in nearly all patients, as soon as two days following vaccination.
“The prerequisite for lasting tumor control and prolonged remission is not only to convert patients with minimal residual disease to an MRD-negative state but also to stabilize it,” Erik Manting, PhD, CEO of DCprime, said. “The interim results … indicate that our relapse cancer vaccination strategy can achieve this goal by inducing a tumor-specific immune response and transforming the prognosis for long-term survival in AML.”
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