NATIONAL HARBOR, MD. – Trial results suggest a personalized vaccination approach is feasible and safe, and the vaccine can produce clinical responses in patients with non–small cell lung cancer (NSCLC).
The neoantigen vaccine produced only grade 1 adverse events, yielded responses in patients with epidermal growth factor receptor (EGFR) mutations, and proved particularly effective in patients who were also receiving an EGFR inhibitor.
“EGFR inhibitors seemed to reduce tumor immunosuppression barriers and may enhance antitumor immune responses before and during immunization, suggesting there may be a potential synergy of EGFR with immunotherapies,”, of University of Texas MD Anderson Cancer Center, Houston, said at the annual meeting of the Society for Immunotherapy of Cancer.
The research began with an elderly patient who had heavily pretreated NSCLC (). Dr. Lizee and colleagues used tumor mutational profiling and human leukocyte antigen (HLA) typing to develop a personalized peptide vaccine for the patient. He received the vaccine along with topical imiquimod and had multiple lung tumor nodules regress. However, the patient also had liver metastasis that remained refractory to treatment, and he ultimately died.
To investigate this treatment approach in a larger group, Dr. Lizee and colleagues began a phase 1b trial of patients with advanced NSCLC (). As with the prior patient, the researchers designed personalized peptide vaccines for the trial subjects based on mutational profiling of 508 cancer-associated genes and high-resolution HLA typing. The peptides were selected based on nonsynonymous somatic tumor–associated mutations with variant allele frequency greater than 0.04 and the highest predicted neoantigen peptide binding to each patient’s HLA class I and II molecules. The vaccines targeted up to eight independent somatic mutations (mean, 3.75 mutations).
In all, 31 patients provided lung tumor biopsies and peripheral blood for mutational and HLA analyses. The researchers designed 27 personalized neoantigen vaccines, and 24 patients were ultimately vaccinated. This translates to a vaccination rate of 77%, which suggests this treatment approach is feasible, Dr. Lizee said.
Of the 24 vaccinated patients, 18 had adenocarcinoma, and 6 had squamous cell carcinoma. All patients had received multiple prior therapies, including surgery, chemotherapy, radiation, and EGFR inhibitors.
Each patient was vaccinated with a personalized mixture of short and long neoantigen peptides (mean, 9.4 peptides) dissolved in isotonic saline. Patients received at least 12 weekly immunizations and had topical imiquimod applied over the injection site for costimulation through toll-like receptor 7. The 16 patients with EGFR mutations were given the option of continuing on an EGFR inhibitor, and 9 patients elected to do so.
Dr. Lizee said this treatment approach was “very safe,” with only grade 1 treatment-related adverse events. The events were fatigue (n = 2), rash (n = 1), and fever (n = 1).
Seven patients achieved a response after vaccination, and one patient achieved a complete response. All seven responders had EGFR mutations, and four of them were receiving an EGFR inhibitor.
The patients on an EGFR inhibitor had significantly better overall survival than that of EGFR-mutated patients who had stopped taking an EGFR inhibitor – 13.8 months and 7.6 months, respectively (P = .038).
Immune profiling revealed that neoantigen-specific T-cell reactivity was associated with clinical responses. The researchers observed EGFR neoantigen-specific T-cell responses in five responders. In three responders, the strongest response was against a peptide encompassing the L858R driver mutation.
The researchers also found evidence of synergy between EGFR inhibitor therapy and the peptide vaccine. EGFR inhibition caused immunomodulatory pathways in EGFR-mutated cancer cells to favor immune-cell infiltration and HLA-mediated antigen presentation.
“Our mechanistic working model is that, in the circulation, the personalized vaccine increased the T-cell frequency,” Dr. Lizee said. “The EGFR inhibitor increased chemokines and antigen presentation at the tumor site, which then attracted those T cells to migrate to the tumor. Then, recognition of the antigen caused interferon gamma [to increase], which caused, potentially, a feed-forward loop by increasing chemokines and antigen presentation further.”
This research is sponsored by Tianjin Beichen Hospital and funded by Tianjin HengJia Biotechnology Development Co. Ltd. Dr. Lizee disclosed a consulting relationship with Tianjin HengJia Biotechnology Development Co. Ltd.
SOURCE: Lizee G et al. SITC 2019. .