Dataset Information

Phase 1 study of safety, tolerability and immunogenicity of the human telomerase (hTERT)-encoded DNA plasmids INO-1400 and INO-1401 with or without IL-12 DNA plasmid INO-9012 in adult patients with solid tumors.

ABSTRACT:

Background

Human telomerase reverse transcriptase (hTERT) is frequently classified as a 'universal' tumor associated antigen due to its expression in a vast number of cancers. We evaluated plasmid DNA-encoded hTERT as an immunotherapy across nine cancer types.

Methods

A phase 1 clinical trial was conducted in adult patients with no evidence of disease following definitive surgery and standard therapy, who were at high risk of relapse. Plasmid DNA encoding one of two hTERT variants (INO-1400 or INO-1401) with or without plasmid DNA encoding interleukin 12 (IL-12) (INO-9012) was delivered intramuscularly concurrent with the application of the CELLECTRA constant-current electroporation device 4 times across 12 weeks. Safety assessments and immune monitoring against native (germline, non-mutated, non-plasmid matched) hTERT antigen were performed. The largest cohort of patients enrolled had pancreatic cancer, allowing for additional targeted assessments for this tumor type.

Results

Of the 93 enrolled patients who received at least one dose, 88 had at least one adverse event; the majority were grade 1 or 2, related to injection site. At 18 months, 54.8% (51/93) patients were disease-free, with median disease-free survival (DFS) not reached by end of study. For patients with pancreatic cancer, the median DFS was 9 months, with 41.4% of these patients remaining disease-free at 18 months. hTERT immunotherapy induced a de novo cellular immune response or enhanced pre-existing cellular responses to native hTERT in 96% (88/92) of patients with various cancer types. Treatment with INO-1400/INO-1401±INO-9012 drove hTERT-specific IFN-γ production, generated hTERT-specific CD4+ and CD8+ T cells expressing the activation marker CD38, and induced hTERT-specific activated CD8 +CTLs as defined by cells expressing perforin and granzymes. The addition of plasmid IL-12 adjuvant elicited higher magnitudes of cellular responses including IFN-γ production, activated CD4+ and CD8+ T cells, and activated CD8+CTLs. In a subset analysis of pancreatic cancer patients, the presence of immunotherapy-induced activated CD8+ T cells expressing PD-1, granzymes and perforin correlated with survival.

Conclusions

Plasmid DNA-encoded hTERT/IL-12 DNA immunotherapy was well-tolerated, immune responses were noted across all tumor types, and a specific CD8+ phenotype increased by the immunotherapy was significantly correlated with survival in patients with pancreatic cancer.

SUBMITTER: Vonderheide RH

PROVIDER: S-EPMC8261871 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Human telomerase reverse transcriptase (hTERT) is an antigen that may represent a target for a novel anti-cancer strategy. A pilot, phase I study tested the safety and feasibility of a prime-boost immunization regimen based on V935, an adenoviral type 6 vector vaccine expressing a modified version of hTERT, administered alone or in combination with V934, a DNA plasmid that also expresses the same antigen and is delivered using the electroporation injection technique. METHODS:Treatments: Group #1 received two doses (low-dose: 0.5?×?109 vg, and high-dose: 0.5?×?1011 vg) of V935 followed by a 4-week observation period. Group #2 received three doses of V934-electroporation and two doses of V935 following a 4-week observation period. Doses were low-dose V934 (0.25 mg of plasmid) with low-dose V935 (0.5?×?109 vg); high-dose V934 (2.5 mg of plasmid) with high-dose V935 (0.5?×?1011 vg). Group #3 received five doses of V934-EP and two doses of V935: V934 was administered IM every 2 weeks for five doses. Following a 4-week observation period, V935 was administered IM every 2 weeks for two doses followed by a 4-week observation period. One (1) dose level was tested in treatment group #3: high-dose V934 (2.5 mg of plasmid), in combination with high-dose V935 (0.5?×?1011 vg). Immunogenicity was measured by ELISPOT assay and three pools of peptides encompassing the sequence of hTERT. RESULTS:In total, 37 patients affected by solid tumors (prostate cancer in 38%) were enrolled. The safety profile of different regimens was good and comparable across groups, with no severe adverse events, dose-limiting toxicities or treatment discontinuations. As expected, the most common adverse events were local reactions. A significant increase in ELISPOT responses against hTERT peptide pool 2 was observed (p?<?0.01), while no evidence of boosting was observed for peptide pools 1 and 3. This was also evident for group #1 and #2 separately. In patients with prostate cancer, there was a significant increase in ELISPOT response against hTERT peptide pool 2 following immunization (p?<?0.01), regardless of previous therapy, immunosuppressing agents, or adenoviral type 6 titers at screening. CONCLUSION:Our results suggest the safety and feasibility of V934/V935 hTERT vaccination in cancer patients with solid tumors Trial Registration Name of the registry: ClinicalTrial.gov Trial registration number: NCT00753415 Date of registration: 16 September 2008 Retrospectively registered URL of trial registry record: https://clinicaltrials.gov/ct2/results?cond=&term=NCT00753415&cntry=&state=&city=&dist=.

Project description:BackgroundTelomerase is a reverse transcriptase that maintains the telomeres of linear chromosomes and preserves genomic integrity. The core components are a catalytic protein subunit, the telomerase reverse transcriptase (TERT), and an RNA subunit, the telomerase RNA (TR). Telomerase is unique in its ability to catalyze processive DNA synthesis, which is facilitated by telomere-specific DNA-binding domains in TERT called anchor sites. A conserved glutamine residue in the TERT N-terminus is important for anchor site interactions in lower eukaryotes. The significance of this residue in higher eukaryotes, however, has not been investigated.Methodology/principal findingsTo understand the significance of this residue in higher eukaryotes, we performed site-directed mutagenesis on human TERT (hTERT) Q169 to create neutral (Q169A), conservative (Q169N), and non-conservative (Q169D) mutant proteins. We show that these mutations severely compromise telomerase activity in vitro and in vivo. The functional defects are not due to abrogated interactions with hTR or telomeric ssDNA. However, substitution of hTERT Q169 dramatically impaired the ability of telomerase to incorporate nucleotides at the second position of the template. Furthermore, Q169 mutagenesis altered the relative strength of hTERT-telomeric ssDNA interactions, which identifies Q169 as a novel residue in hTERT required for optimal primer binding. Proteolysis experiments indicate that Q169 substitution alters the protease-sensitivity of the hTERT N-terminus, indicating that a conformational change in this region of hTERT is likely critical for catalytic function.Conclusions/significanceWe provide the first detailed evidence regarding the biochemical and cellular roles of an evolutionarily-conserved Gln residue in higher eukaryotes. Collectively, our results indicate that Q169 is needed to maintain the hTERT N-terminus in a conformation that is necessary for optimal enzyme-primer interactions and nucleotide incorporation. We show that Q169 is critical for the structure and function of human telomerase, thereby identifying a novel residue in hTERT that may be amenable to therapeutic intervention.