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Local administration of CpG-B prolongs RFS in early-stage melanoma
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Patients with stage I or stage II melanoma who received the immune system-boosting agent CpG-B appeared less likely to experience disease recurrence than patients who received placebo, according to study results presented at the CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference in New York.
CpG-B (Pfizer) — a reagent that resembles bacterial DNA — activates an immune response, causing it to attack the melanoma cells, according to Tanja D. de Gruijl, PhD, professor and head of the immunotherapy lab in the department of medical oncology at VU University Medical and Cancer Center in Amsterdam.
Tanja D. de Gruijl
“Even though stage I and stage II melanomas can be removed surgically, in a considerable proportion of patients cells from the tumor have already spread and eventually lead to tumor recurrence,” de Gruijl said in a press release. “We set out to investigate whether intradermal injection of the immune-stimulatory compound CpG-B around the site of surgical removal of the primary tumor could boost patients’ anti-melanoma immune responses and provide local and systemic protection against early metastatic events that could otherwise lead to tumor recurrence.”
The analysis included data from two randomized, controlled phase 2 trials composed of 52 patients with stage I or stage II melanoma. Researchers assigned the patients an intradermal injection of CpG-B or saline directly adjacent to the excision site of the primary melanoma tumor. The injections were administered 7 days and 2 days before a second surgical excision and sentinel lymph node biopsy.
After a median follow-up of 76.5 months, only two of the 30 patients (6.7%) assigned CpG-B had disease recurrence compared with nine of 22 patients (40.9%) assigned placebo.
“The apparent clinical effect was much stronger than we had anticipated and underlines the powerful ability of the immune system, provided it is properly activated, to control melanoma,” de Gruijl said in the release.
Disease-specific survival rates were 77.2% in the placebo arm compared with 93.3% in the CpG-B arm.
After pathologically examining the sentinel lymph nodes, researchers detected a difference in the proportion of pathologically stage III patients in each arm. A significantly smaller proportion of patients in the CpG-B group positive sentinel lymph nodes than patients in the control arm (10% vs. 36.4%; P = .037).
There were some limitations with this study, including that the data were derived from two phase 2 trials with low enrollment and that different doses of CpG-B were used in each of the trials.
This would mean a large, randomized, phase 3 trial would be necessary to validate these findings, and de Gruijl said that her team is already in the planning stages for such a trial. – by Anthony SanFilippo
Reference:
de Gruijl TD, et al. Abstract A050. Presented at: CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference; Sept. 16-19, 2015; New York.
Disclosure: The study was funded by the Fritz Ahlqvist Foundation. Pfizer provided CpG-B for the trial. de Gruijl reported no relevant financial disclosures. HemOnc Today was unable to obtain a list of the other researchers’ relevant financial disclosures at the time of reporting.