SAN ANTONIO, TX — Researchers reported positive results today for phase IIb testing of a vaccine for high-risk melanoma patients.

John William Myers, MD, of the San Antonio Military Medical Center presented the interim results at the 2018 American Society of Clinical Oncology Annual Meeting in Chicago.1

Myers led a high-profile team of researchers who have developed an autologous tumor lysate, particle loaded, dendritic cell (TLPLDC) vaccine. Previous studies have shown the vaccine produced objective tumor response in metastatic patients and that it is safe and immunogenic. Today’s presentation discussed outcomes from a trial of the TLPLDC vaccine in stage III and IV melanoma patients.

All 120 patients in the study had previously undergone definitive surgery and received standard of care therapies. Patients receiving the vaccine were an average of eight years older than those receiving placebo, 65 vs 57 years. Both groups had three times as many patients with stage III disease as with stage IV. The groups had no other significant differences in treatment, demographics or clinical characteristics.

The researchers randomized the participants to receive the vaccine (83) or placebo (37) within three months of the conclusion of standard of care treatment. Patients received the vaccine or placebo through six intradermal inoculations administered at initiation and one, two, six, 12 and 18 months later.

The researchers had followed the patients for an average follow up of 12. 6 months at the time of the interim analysis. Follow up is planned for two years. For this report, they evaluated outcomes based on both the intent to treat population and a per treatment basis which excluded recurrences that occurred during the first six months of the vaccine series.

The intent to treat analysis showed no difference in recurrence rates, which were 56.6% for those who received the vaccine and 54.1% for those who received placebo. Outcomes in the per treatment analysis, however, were more promising. Looking at recurrence rates after the first six months, the vaccine group had a rate of 29.6% compared to 43.3% for those in the placebo group.

Patients experienced no serious adverse events and no immune-related adverse events. While 33% had some adverse event, 98.6% of them were grade 1 or 2.

Based on the results, the researchers concluded that the TLPLDC vaccine is safe for patients and is associated with minimal toxicity. Among patients who completed the first three inoculations in the vaccine series, “there is a strong trend toward fewer recurrences,” the study team wrote.

The researchers will perform a second analysis to determine disease free survival at two years, but they said that current results provide support for a phase III trial.

1Myers JW, Clifton GT, Hale DF, et al. Interim analysis of a prospective, randomized, double blind, placebo controlled, phase IIb trial of the TLPLDC vaccine to prevent recurrence in resected stage III or IV melanoma patients. J Clin Oncol 36, 2018 (suppl; abstr 9525).