Clonal Neoantigen: Emerging "Mechanism-based" Biomarker of Immunotherapy Response.

Clonal mutations represent the initiating molecular defects related to cellular transition of a normal phenotype to a malignant phenotype. Molecular genomic assessment utilizing next generation and whole exome sequencing is now being increasingly applied to biomarker determination to refine the use of targeted immune therapies. Case examples followed by retrospective study assessment have convincingly demonstrated clonal neoantigens provide a relevant predictor of response to checkpoint inhibition. A meta-analysis, by Litchfield et al., of over 1000 cancer patients from 12 landmark trials demonstrated no clinical benefit to checkpoint inhibitor (CPI) therapy in correlation to high subclonal tumor mutational burden (TMB), whereas high clonal TMB was found to be significantly correlated with better overall survival (p = 0.000000029). We discuss the mechanism of clonal vs. subclonal neoantigen targeting relationship to homologous recombination proficient (HRP) profile, evidence of preclinical and clinical benefit related to clonal neoantigens, and review a novel developing therapy called Vigil®, designed to expand the clonal neoantigen targeting effector cell populations. Vigil® is an autologous cellular immunotherapy which is designed to carry the full set of personal clonal neoantigens. Phase 2b results demonstrate a durable recurrence-free survival (RFS) and overall survival (OS) advantage for Vigil® in a subset ovarian cancer population with an HRP cancer profile.

Pilot Study of Recurrent Ewing's Sarcoma Management with Vigil/Temozolomide/Irinotecan and Assessment of Circulating Tumor (ct) DNA.

PURPOSE: Treatment options for recurrent or refractory Ewing's sarcoma (ES) are limited. Vigil is a novel autologous tumor cell therapy expressing bi-shRNA furin/GMCSF plasmid, which previously demonstrated monotherapy activity in advanced ES. Herein we report safety and evidence of benefit to Vigil for ES as potential treatment. PATIENTS AND METHODS: In this pilot trial, eligible patients with recurrent or refractory ES who failed initial standard-of-care therapy received treatment with temozolomide (TEM) 100 mg/m2/day oral and irinotecan (IRI) 50 mg/m2/day oral, Days 1 to 5, in combination with Vigil (1 × 106-107 cells/mL/day intradermal, Day 15), every 21 days (Vigil/TEM/IRI). Objective response rate (ORR) by RECIST v1.1, progression-free survival (PFS), and overall survival (OS) were assessed. Circulating tumor (ct) DNA analysis was done by patient-specific droplet digital PCR on baseline and serially collected on-treatment samples. RESULTS: Eight of 10 enrolled patients were evaluable for safety and efficacy (mean age 24.6; 12.6-46.1 years old); 2 did not receive Vigil. Seven of 8 patients previously received TEM/IRI. No Vigil-related adverse events were reported. Common ≥Grade 3 chemotherapy-related toxicity included neutropenia (50%) and thrombocytopenia (38%). We observed two partial response patients by RECIST; both showed histologic complete response without additional cancer therapy. Median PFS was 8.2 months (95% confidence interval, 4.3-NA). Five patients showed stable disease or better for ≥6 months. Patient-specific EWS/FLI1 ctDNA was detectable in all 8 evaluable patients at baseline. Changes in ctDNA levels corresponded to changes in disease burden. CONCLUSIONS: Results demonstrated safety of combination Vigil/TEM/IRI.

ENTPD1/CD39 as a predictive marker of treatment response to gemogenovatucel-T as maintenance therapy in newly diagnosed ovarian cancer.

Background: Broadened use of predictive molecular and phenotypic profiling amongst oncologists has facilitated optimal integration of targeted- and immuno-therapeutics into clinical care. However, the use of predictive immunomarkers in ovarian cancer (OC) has not consistently translated into clinical benefit. Vigil (gemogenovatucel-T) is a novel plasmid engineered autologous tumor cell immunotherapy designed to knock down the tumor suppressor cytokines, TGFß1 and TGFß2, augment local immune function via increased GMCSF expression and enhance presentation of clonal neoantigen epitopes. Methods: All patients enrolled in the VITAL trial (NCT02346747) of maintenance Vigil vs. placebo as front-line therapy with homologous recombination proficient (HRP) stage IIIB-IV newly diagnosed ovarian cancer underwent NanoString gene expression analysis. Tissue was obtained from surgically resected ovarian tumor tissue following surgical debulking. A statistical algorithm was used to analyze the NanoString gene expression data. Results: Using the NanoString Statistical Algorithm (NSA), we identify high expression of ENTPD1/CD39 (which functions as the rate-limiting step in the production of the immune suppressor adenosine from ATP to ADP) as a presumptive predictor of response to Vigil versus placebo regardless of HRP status on the basis of relapse free survival (median not achieved vs 8.1 months, p = 0.00007) and overall survival (median not achieved vs 41.4 months, p = 0.013) extension. Conclusion: NSA should be considered for application to investigational targeted therapies in order to identify populations most likely to benefit from treatment, in preparation for efficacy conclusive trials.

Treatment options are limited in patients with advanced stage ovarian cancer. Treatments that stimulate the immune system to target the cancer are sometimes effective, however determining which patients will have benefit has been difficult. It is therefore important to develop new markers to predict which patients will respond to therapy. In this study, we looked at the levels of a large number of genes in tumors from patients treated with Vigil (gemogenovatucel-T), a treatment that modifies patient's own tumor cells to activate the immune system. We demonstrate that high expression of a gene named ENTPD1/CD39 predicts a positive response to Vigil therapy. This finding could help clinicians to determine which patients might benefit from Vigil treatment and therefore might guide decisions on who should receive this treatment.

Pilot Study of Combination Gemogenovatucel-T (Vigil) and Durvalumab in Women With Relapsed BRCA-wt Triple-Negative Breast or Ovarian Cancer.

Background: Gemogenovatucel-T (Vigil) is a triple-function autologous tumor cell immunotherapy which expresses granulocyte-macrophage colony-stimulating factor and decreases expression of furin and downstream TGF-ß1 and TGF-ß2. Vigil has suggested survival benefit in frontline maintenance ovarian cancer patients who are BRCA-wt. In addition, Vigil demonstrates relapse-free and overall survival advantage in homologous recombination-proficient patients with OC. Further evidence of clinical benefit and safety has been demonstrated in combination with atezolizumab. Methods: In this pilot study (NCT02725489), the concurrent combination of the programmed death-ligand 1 (PD-L1) inhibitor durvalumab and Vigil was explored in advanced BRCA-wt relapsed triple-negative breast cancer (TNBC) patients and stage III-IV recurrent/refractory OC patients. Patients received the combination regimen of Vigil (1 × 10e6-10e7 cells/dose intradermally, up to 12 doses) and durvalumab (1500 mg/dose intravenous infusion, up to 12 months) once every 4 weeks. The primary objective was to evaluate safety of this combination. The study included 13 BRCA-wt patients (TNBC, n = 8; OC, n = 5). Results: The most common treatment-emergent adverse events (⩾20%) in all patients included injection-site reaction (92.3%), myalgia (38.5%), bruise at injection site (23.1%), and pruritus (23.1%). Three grade 3 treatment-related adverse events were observed and related to durvalumab. There were no grade 4/5 treatment-related adverse events. Median progression-free survival was 7.1 months and the median overall survival was not reached. Prolonged progression-free survival was improved in patients with PD-L1+ tumors (n = 8, hazard ratio = 0.304, 95% confidence interval, 0.0593-1.56, 1-sided P = .04715) compared with those with PD-L1- tumors. Conclusions: Vigil plus durvalumab was well tolerated and showed promising clinical activity in advanced BRCA-wt TNBC and stage III-IV recurrent/refractory OC patients.

Network based analysis identifies TP53m-BRCA1/2wt-homologous recombination proficient (HRP) population with enhanced susceptibility to Vigil immunotherapy.

Thus far immunotherapy has had limited impact on ovarian cancer. Vigil (a novel DNA-based multifunctional immune-therapeutic) has shown clinical benefit to prolong relapse-free survival (RFS) and overall survival (OS) in the BRCA wild type and HRP populations. We further analyzed molecular signals related to sensitivity of Vigil treatment. Tissue from patients enrolled in the randomized double-blind trial of Vigil vs. placebo as maintenance in frontline management of advanced resectable ovarian cancer underwent DNA polymorphism analysis. Data was generated from a 981 gene panel to determine the tumor mutation burden and classify variants using Ingenuity Variant Analysis software (Qiagen) or NIH ClinVar. Only variants classified as pathogenic or likely pathogenic were included. STRING application (version 1.5.1) was used to create a protein-protein interaction network. Topological distance and probability of co-mutation were used to calculated the C-score and cumulative C-score (cumC-score). Kaplan-Meier analysis was used to determine the relationship between gene pairs with a high cumC-score and clinical parameters. Improved relapse free survival in Vigil treated patients was found for the TP53m-BRCAwt-HRP group compared to placebo (21.1 months versus 5.6 months p = 0.0013). Analysis of tumor mutation burden did not reveal statistical benefit in patients receiving Vigil versus placebo. Results suggest a subset of ovarian cancer patients with enhanced susceptibility to Vigil immunotherapy. The hypothesis-generating data presented invites a validation study of Vigil in target identified populations, and supports clinical consideration of STRING-generated network application to biomarker characterization with other cancer patients targeted with Vigil.

Proof of principle study of sequential combination atezolizumab and Vigil in relapsed ovarian cancer.

Vigil® is a personalized vaccine that enhances tumor neoantigen expression. We investigated for the first time safety and efficacy of Vigil in combination with atezolizumab in relapsed ovarian cancer (OC) patients. This is a randomized, Phase 1 study of Vigil, an autologous tumor tissue transfected vaccine encoding for GMCSF and bi-shRNA-furin thereby creating enhanced immune activation and TGFß expression control. Part 1 is a safety assessment of Vigil (1 × 10e7 cells/mL/21 days) plus atezolizumab (1200 mg/21 days). Part 2 is a randomized study of Vigil first (Vigil-1st) or atezolizumab first (Atezo-1st) for two cycles followed by the combination of both agents. The primary endpoint of the study was the determination of safety. Twenty-four patients were enrolled in the study; three patients to Part 1 and 21 to Part 2. Patients in Part 1 completed combination therapy without dose-limiting toxicity justifying expansion to Part 2. Twenty-one patients were randomized (1:1) to Part 2 to Vigil-1st (n = 11) or Atezo-1st (n = 10). Grade 3/4 treatment-related adverse events of Atezo-1st vs. Vigil-1st were 17.2% vs. 5.1%. Median overall survival (OS) was not reached (NR) (Vigil-1st) vs. 10.8 months (Atezo-1st) (hazard ratio [HR] 0.33). The exploratory subset analysis of BRCAwt suggested improved OS benefit [NR in Vigil-1st vs. 5.2 months in Atezo-1st, HR 0.16, p 0.027]. The Vigil-1st combination therapy with atezolizumab was safe and results in support continued investigation in BRCAwt patients.

Gemogenovatucel-T (Vigil) maintenance immunotherapy: 3-year survival benefit in homologous recombination proficient (HRP) ovarian cancer.

OBJECTIVE: Previously, Vigil demonstrated clinical benefit to prolong relapse free and overall survival in the BRCA wild-type (BRCA-wt), homologous recombination proficient (HRP) patient population. Here we provide long term follow up of 3 years in the HRP patient population enrolled in the Phase 2b VITAL study. METHODS: HRP patients treated with Vigil (n = 25) or placebo (n = 20) who were enrolled in the Phase 2b, double-blind, placebo-controlled (VITAL study, NCT02346747) were followed for safety, OS and RFS. OS and RFS from time of randomization (immediately prior to maintenance therapy) and from debulking tissue procurement time points were analyzed by Kaplan-Meier (KM) and restricted mean survival time (RMST) analysis. RESULTS: OS for Vigil treated patients at 3 years has not yet reached median OS time point (95% CI 41.6 months to not achieved) compared to 26.9 (95% CI 17.4 months to not achieved) in placebo treated patients (HR 0.417 p = 0.020). Three year RFS also showed benefit to Vigil (stratified HR 0.405, p = 0.011) and no long term toxicity to Vigil was observed. Three year OS for Vigil of 70% vs. 40% for placebo from time of randomization was observed (p = 0.019). RMST analysis was also significant for OS (45.7 vs. 32.8 months, p = 0.008) and RFS (p = 0.025). CONCLUSION: In conclusion, results suggest durable activity of Vigil on RFS and OS and support further evaluation of Vigil in HRP ovarian cancer.

Case Report: Marked Survival Advantage of Two Colorectal Cancer Patients with Liver Metastases Treated with Vigil and FOLFOX-6.

Colorectal cancer is the third most diagnosed cancer in the United States. Five-year survival rates remain low and many patients will develop liver metastasis. Vigil is an immunotherapy manufactured from autologous tumor cells and transfected ex vivo with a plasmid that encodes the GM-CSF gene and bifunctional shRNA construct to knockdown furin. Here, we report two patients with colorectal cancer and resectable liver metastasis entered into a clinical trial involving Vigil in combination with standard of care modified FOLFOX-6 chemotherapy. The first dose of Vigil was given two weeks before the modified FOLFOX-6 regimen. Vigil treatment continued until Vigil supply was exhausted. Both patients exhibited remarkable response to combination therapy, demonstrating no evidence of disease recurrence for over eight years. Additionally, both patients demonstrated systemic immune response to Vigil therapy as tested by ELISPOT.

Long-Term Follow-Up of Gemogenovatucel-T (Vigil) Survival and Molecular Signals of Immune Response in Recurrent Ovarian Cancer.

AIM: To determine the relationship between gene expression profile (GEP) and overall survival (OS) by NanoString following treatment with Vigil. PATIENTS AND METHODS: Recurrent ovarian cancer patients (n = 21) enrolled in prior clinical trials. RESULTS: GEP stratified by TISHIGH vs. TISLOW demonstrated OS benefit (NR vs. 5.8 months HR 0.23; p = 0.0379), and in particular, MHC-II elevated baseline expression was correlated with OS advantage (p = 0.038). Moreover, 1-year OS was 75% in TISHIGH patients vs. 25% in TISLOW (p = 0.03795). OS was also correlated with positive γ-IFN ELISPOT response, 36.8 vs. 23.0 months (HR 0.19, p = 0.0098). CONCLUSION: Vigil demonstrates OS benefit in correlation with TISHIGH score, elevated MHC-II expression and positive γ-IFN ELISPOT in recurrent ovarian cancer patients.

Corrigendum to "Long-term follow-up of Phase 2A trial results involving advanced ovarian cancer patients treated with Vigil® in frontline maintenance" [Gynecol. Oncol. Rep. 34 (2020) 100648].

[This corrects the article DOI: 10.1016/j.gore.2020.100648.].

Gemogenovatucel-T (Vigil) immunotherapy demonstrates clinical benefit in homologous recombination proficient (HRP) ovarian cancer.

OBJECTIVE: Recently, Vigil showed significant clinical benefit with improvement in relapse free (RFS) and overall survival (OS) in pre-planned subgroup analysis in stage III/IV newly diagnosed ovarian cancer patients with BRCA wild type (BRCA-wt) molecular profile. Here we analyze homologous recombination (HR) status of patients enrolled in the Phase 2b VITAL study and determine clinical benefit of Vigil in HR proficient (P) patients. METHODS: Patients were previously enrolled in a Phase 2b, double-blind, placebo-controlled trial. All were in complete response with Stage III/IV high grade serious, endometroid or clear cell ovarian cancer. HR status was determined using MyChoice®CDx score (<42 = HRP) (Myriad Genetics, Inc., UT). Post-hoc analyses were carried out using Kaplan Meier and restricted mean survival time (RMST) analysis to evaluate RFS and OS based on HR deficiency (D) status. RESULTS: RFS was improved with Vigil (n = 25) in HRP patients compared to placebo (n = 20) (HR = 0.386; 90% CI 0.199-0.750; p = 0.007), results were verified by RMST (p = 0.017). Similarly, OS benefit was observed in Vigil group compared to placebo (HR = 0.342; 90% CI 0.141-0.832; p = 0.019). Results with OS were also verified with RMST (p = 0.008). CONCLUSION: Vigil exhibited clinical benefit in HRP molecular profile patients.

Gemogenovatucel-T (Vigil) immunotherapy as maintenance in frontline stage III/IV ovarian cancer (VITAL): a randomised, double-blind, placebo-controlled, phase 2b trial.

BACKGROUND: Gemogenovatucel-T is an autologous tumour cell vaccine manufactured from harvested tumour tissue, which specifically reduces expression of furin and downstream TGF-ß1 and TGF-ß2. The aim of this study was to determine the safety and efficacy of gemogenovatucel-T in front-line ovarian cancer maintenance. METHODS: This randomised, double-blind, placebo-controlled, phase 2b trial involved 25 hospitals in the USA. Women aged 18 years and older with stage III/IV high-grade serous, endometrioid, or clear cell ovarian cancer in clinical complete response after a combination of surgery and five to eight cycles of chemotherapy involving carboplatin and paclitaxel, and an Eastern Cooperative Oncology Group status of 0 or 1 were eligible for inclusion in the study. Patients were randomly assigned (1:1) to gemogenovatucel-T or placebo by an independent third party interactive response system after successful screening using randomly permuted block sizes of two and four and stratified by extent of surgical cytoreduction and neoadjuvant versus adjuvant chemotherapy. Gemogenovatucel-T (1 × 107 cells per injection) or placebo was administered intradermally (one per month) for a minimum of four and up to 12 doses. Patients, investigators, and clinical staff were masked to patient allocation until after statistical analysis. The primary endpoint was recurrence-free survival, analysed in the per-protocol population. All patients who received at least one dose of gemogenovatucel-T were included in the safety analysis. The study is registered with ClinicalTrials.gov, NCT02346747. FINDINGS: Between Feb 11, 2015, and March 2, 2017, 310 patients consented to the study at 22 sites. 217 were excluded. 91 patients received gemogenovatucel-T (n=47) or placebo (n=44) and were analysed for safety and efficacy. The median follow-up from first dose of gemogenovatucel-T was 40·0 months (IQR 35·0-44·8) and from first dose of placebo was 39·8 months (35·5-44·6). Recurrence-free survival was 11·5 months (95% CI 7·5-not reached) for patients assigned to gemogenovatucel-T versus 8·4 months (7·9-15·5) for patients assigned to placebo (HR 0·69, 90% CI 0·44-1·07; one-sided p=0·078). Gemogenovatucel-T resulted in no grade 3 or 4 toxic effects. Two patients in the placebo group had five grade 3 toxic events, including arthralgia, bone pain, generalised muscle weakness, syncope, and dyspnea. Seven patients (four in the placebo group and three in the gemogenovatucel-T group) had 11 serious adverse events. No treatment-related deaths were reported in either of the groups. INTERPRETATION: Front-line use of gemogenovatucel-T immunotherapy as maintenance was well tolerated but the primary endpoint was not met. Further investigation of gemogenovatucel-T in patients stratified by BRCA mutation status is warranted. FUNDING: Gradalis.

Phase II study of Vigil® DNA engineered immunotherapy as maintenance in advanced stage ovarian cancer.

OBJECTIVES: The majority of women with Stage III/IV ovarian cancer who achieve clinical complete response with frontline standard of care will relapse within 2years. Vigil immunotherapy, a GMCSF/bi-shRNA furin DNA engineered autologous tumor cell (EATC) product, demonstrated safety and induction of circulating activated T-cells against autologous tumor in Phase I trial Senzer et al. (2012, 2013) . Our objectives for this study include evaluation of safety, immune response and recurrence free survival (RFS). METHODS: This is a Phase II crossover trial of Vigil (1.0×107 cells/intradermal injection/month for 4 to 12 doses) in Stage III/IV ovarian cancer patients achieving cCR (normal imaging, CA-125≤35units/ml, physical exam, and no symptoms suggestive of the presence of active disease) following primary surgical debulking and carboplatin/paclitaxel adjuvant or neoadjuvant chemotherapy. Patients received Vigil or standard of care during the maintenance period. RESULTS: Forty-two patients were entered into trial, 31 received Vigil and 11 received standard of care. No≥Grade 3 toxicity related to product was observed. A marked induction of circulating activated T-cell population was observed against individual, pre-processed autologous tumor in the Vigil arm as compared to pre-Vigil baseline using IFNγ ELISPOT response (30/31 negative ELISPOT pre Vigil to 31/31 positive ELISPOT post Vigil, median 134 spots). Moreover, in correlation with ELISPOT response, RFS from time of procurement was improved (mean 826days/median 604days in the Vigil arm from mean 481days/median 377days in the control arm, p=0.033). CONCLUSION: In conjunction with the demonstrated safety, the high rate of induction of T-cell activation and correlation with improvement in RFS justify further Phase II/III assessment of Vigil.