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Abstract
Background MEDI5395 is a recombinant attenuated Newcastle disease virus engineered to express a human granulocyte-macrophage colony-stimulating factor transgene. Preclinically, MEDI5395 demonstrated broad oncolytic activity, augmented by concomitant programmed cell death-1/programmed cell death ligand-1 (PD-L1) axis blockade. Durvalumab is an anti-PD-L1 immune checkpoint inhibitor approved for the treatment of various solid tumors. We describe the results of the first-in-human study combining intravenous MEDI5395 with durvalumab in patients with advanced solid tumors.
Methods This phase I, open-label, multicenter, dose-escalation, dose-expansion study recruited adult patients with advanced solid tumors, who had relapsed or were refractory or intolerant to ≥1 prior line of standard treatment. MEDI5395 was administered intravenously as six doses over 15–18 days. The dose-escalation phase assessed four-dose levels (108, 109, 1010, 1011 focus forming units (FFU)) of MEDI5395, with sequential or delayed durvalumab. Durvalumab 1500 mg was administered intravenously every 4 weeks up to 2 years. The dose-expansion phase was not initiated. The primary objectives were to evaluate safety and tolerability, dose-limiting toxicities (DLTs) and the dose and schedule of MEDI5395 plus durvalumab administration. Secondary objectives included the assessment of the efficacy, pharmacokinetics, pharmacodynamics, and immunogenicity of MEDI5395.
Results 39 patients were treated with MEDI5395; 36 patients also received durvalumab. All 39 patients experienced ≥1 treatment-emergent adverse event (TEAE), most commonly fatigue (61.5%), nausea (53.8%) and chills (51.3%). Grade 3–4 TEAEs occurred in 27 (69.2%) patients; these were deemed MEDI5395-related in 12 (30.8%) patients. Two patients experienced a DLT, and the maximum tolerated dose of MEDI5395 with sequential and delayed durvalumab at study termination was 1011 and 1010 FFU, respectively. Four patients (10.3%) achieved a partial response (PR). Patients with PR or stable disease tended to have higher baseline PD-L1 and CD8+ levels in their tumor tissue. A tendency to dose-dependent pharmacokinetics of the viral genome was observed in whole blood and a tendency to dose-dependent viral shedding was observed in saliva and urine. Neutralizing antibodies were observed in all patients but did not appear to impact efficacy negatively.
Conclusion This study demonstrates the feasibility, safety and preliminary efficacy of MEDI5395 with durvalumab in patients with advanced solid tumors.
Trial registration number NCT03889275
- Pharmacokinetics - PK
- Immune Checkpoint Inhibitor
- Oncolytic virus
Data availability statement
Data are available upon reasonable request. Data underlying the findings described in this manuscript may be obtained in accordance with AstraZeneca’s data sharing policy described at: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure. Data for studies directly listed on Vivli can be requested through Vivli at www.vivli.org. Data for studies not listed on Vivli could be requested through Vivli at https://vivli.org/members/enquiries-about-studies-not-listed-on-the-vivli-platform/. The AstraZeneca Vivli member page is also available outlining further details: https://vivli.org/ourmember/astrazeneca/.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See http://creativecommons.org/licenses/by-nc/4.0/.
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WHAT IS ALREADY KNOWN ON THIS TOPIC
Preclinical studies and early clinical results have demonstrated the potential of oncolytic viruses (OV) to synergize with immune checkpoint inhibitors, such as durvalumab, to overcome resistance to immune checkpoint blockade. Further, a systemically administered OV, such as MEDI5395, may overcome the limitations experienced with intratumorally administered OVs.
WHAT THIS STUDY ADDS
This first-in-human phase I clinical study demonstrated the safety, tolerability and preliminary efficacy of combining MEDI5395 with durvalumab in patients with advanced solid tumors, with proof-of-concept that MEDI5395 could be detected within the tumor after systemic administration.
HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY
Combination therapy with a systemically administered OV and durvalumab is a feasible treatment option for patients with advanced solid tumors; however, further clinical trials are required to confirm these findings.
Background
Programmed cell death-1 (PD-1) is an immune checkpoint receptor that is expressed on the surface of activated T cells, B cells and other immune cells.1 Programmed cell death ligand-1 (PD-L1) is a surface glycoprotein expressed by specific tumor cells (TC), either constitutively or after exposure to interferon-gamma (IFN-γ), as a mechanism of immune evasion.2 3 When PD-1 and PD-L1 engage, T-cell function is suppressed, which reduces or impairs the function of immune cells that infiltrate the tumor and weakens tumor immunogenicity.4 5 Immune checkpoint inhibitors (ICI) that target the PD-1/PD-L1 axis overcome tumor-mediated immune suppression, leading to antitumor immune responses and prolonged survival in multiple cancer types including advanced melanoma, renal cell carcinoma (RCC) and non-small-cell lung cancer (NSCLC).6–11 Biomarkers of response to PD-1/PD-L1 blockade include cluster of differentiation 8 (CD8)+ T-cell density,12 PD-L1 expression,13 IFN-γ gene expression profile,14 increased tumor mutation burden15 16 and peripheral expansion of CD8+ effector T cells.17 18 However, most patients fail to respond to anti-PD-1/PD-L1 ICIs, and multiple mechanisms detailing primary, adaptive and acquired resistance to ICI have been described including downregulation of major histocompatibility complex and tumor-associated antigens (TAA).19 20 Durvalumab is an anti-PD-L1 ICI approved by the US Food and Drug Administration as monotherapy or in combination with other agents for use in patients with several indications: unresectable locally advanced or metastatic NSCLC; extensive-stage small cell lung cancer; locally advanced or metastatic biliary tract cancer; and unresectable hepatocellular carcinoma.6
Oncolytic viruses (OV) have demonstrated the ability to stimulate immune responses against TAA, augment TAA expression in tumors, and enhance existing responses by targeting suppressive mechanisms.21 OVs can preferentially replicate in TC, self-amplify, and activate antitumor immune responses via both the innate and adaptive immune pathways, through activation of antigen-presenting cells and T-cell mediated antitumor immunity, respectively.22 In addition, genetic modification of OVs to encode immunomodulatory transgenes can enhance oncolytic activity.22 Talimogene laherparepvec (T-VEC) is a genetically modified herpes simplex virus type 1 (HSV-1) OV, designed to selectively replicate in tumors and produce granulocyte-macrophage colony-stimulating factor (GM-CSF) to enhance antigen release and presentation, and improve systemic antitumor immune responses.23 Intralesional administration of T-VEC improved objective response rates (ORR) compared with subcutaneously administered GM-CSF in patients with advanced melanoma.24
Preclinical and early clinical studies with OVs highlight their potential to synergize with ICIs to overcome resistance to immune checkpoint blockade.25–32 While the addition of a PD-1 blockade to T-VEC demonstrated a high ORR and increased immunogenicity and IFN-γ gene expression in a small proof-of-concept trial,30 this combination failed to improve progression-free survival or overall survival versus PD-1 blockade alone in a randomized, double-blinded, placebo-controlled phase III study.33 A second intratumoral HSV-1 OV expressing GM-CSF (RP1) in combination with nivolumab reported 33% ORR in a phase I/II trial in patients with cutaneous melanoma who had progressed on prior anti-PD-L1 therapy,34 prompting the development of a confirmatory phase III trial.35 One limitation in the development of intratumoral agents is the requirement for accessible lesion(s) suitable for injection. We hypothesized that a systemically administered OV would overcome the limitations experienced by prior intratumorally administered OVs.
MEDI5395 is a recombinant attenuated Newcastle disease virus (NDV) engineered to express a human GM-CSF transgene and designed for systemic administration.36 37 Preclinically, MEDI5395 demonstrated broad oncolytic activity and immune-modulatory properties in a variety of human and murine cell lines, and in human xenograft tumor models and murine syngeneic models.36 37 The antitumor effects of MEDI5395 were augmented by concomitant blockade of the PD-1/PD-L1 axis.37 Here, we describe the results from the first-in-human, phase I study of intravenously administered MEDI5395 in combination with the PD-L1 inhibitor durvalumab in patients with advanced solid tumors, including safety, preliminary efficacy, pharmacokinetics, pharmacodynamics, immunogenicity, viral shedding, and biomarker assessment.
Methods
Study design and treatment
This was a phase I, first-in-human, open-label, multicenter study to assess the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of MEDI5395 in combination with sequential and delayed durvalumab schedules in patients with selected advanced solid tumors. The study was registered with relevant institutional review boards and full details of each are included in the declarations section. In the context of studies using attenuated NDV OVs, given that seropositivity against NDV is typically minimal and the anti-NDV human response can be potent in humans,38 we sought to study a lower initial dose followed by higher doses of MEDI5395, and also evaluated both sequential (complete MEDI5395 schedule, followed by durvalumab) and delayed (initial MEDI5395 priming schedule, followed by durvalumab) dosing regimens. The study comprised of dose-escalation and dose-expansion phases (online supplemental figure 1); however, the dose-expansion phase was not initiated. Herein, we present the results of the dose-escalation portion of the study, which assessed four dose levels (108, 109, 1010, and 1011 focus-forming units (FFU)) of MEDI5395 with either sequential (Cohorts 1A to 4A) or delayed (Cohorts 1B to 4B) durvalumab. Dose escalation followed the modified toxicity probability interval algorithm for escalation.39 Dose-escalation decisions were made when 3–12 patients had been enrolled and had provided on-treatment biopsies. Additional patients (up to 18 per cohort) could be enrolled to further characterize a particular dose level; for these additional patients, paired pretreatment and on-treatment biopsies were mandated. Delayed dosing of MEDI5395 with durvalumab in Cohort 1B (online supplemental figure 1) began once Cohort 2A was cleared by the dose-escalation committee (DEC). Initiation of dosing in subsequent delayed dosing cohorts was contingent on DEC clearance of both the prior delayed dose level and the same dose level cohort in the sequential regimen.
Supplemental material
MEDI5395 was administered intravenously as six doses over 15–18 days (with ≥3 days between each of the first three doses and ≥2 days between each subsequent dose). Initially, each participant received the planned dose level of MEDI5395 for all doses. However, a desensitization regimen could be implemented to mitigate the risk of infusion-related reactions (IRR) following the first dose. 40 41 A 1-step, 1-log desensitization regimen was implemented on DEC recommendation after October 2020 for participants treated at 1010 FFU such that the first dose was administered at 109 FFU and the planned dose level (1010 FFU) was given for doses 2 to 6. For patients treated at the 1011 FFU dose level, the DEC endorsed a 1-step, 2-log desensitization regimen (first dose administered at 109 FFU and the planned dose level (1011 FFU) given for doses 2 to 6) or a 2-step, 2-log desensitization regimen (first dose administered at 109 FFU, second dose at 1010 FFU, and the planned dose level (1011 FFU) for doses 3 to 6).
Durvalumab 1500 mg was administered intravenously every 4 weeks for a maximum of 2 years or until radiologically confirmed disease progression, clinical deterioration, withdrawal of consent, or unacceptable toxicity. In the sequential regimen, the first dose of durvalumab was administered 14–21 days after the last dose of MEDI5395. In the delayed dosing regimen, the first dose of durvalumab was given on the same day as the third dose of MEDI5395 and administered ≥1 hour after the end of MEDI5395 administration. Patients benefiting from durvalumab at the data cut-off date were permitted to enter the continued durvalumab treatment period for up to a maximum of 2 years.
Patients
Patients ≥18 years of age with histologically confirmed select advanced solid tumors (triple-negative breast cancer, colorectal cancer, hepatocellular carcinoma, head and neck squamous cell carcinoma, RCC, NSCLC, or melanoma) were eligible. Eligible patients had to have relapsed on, or were refractory or intolerant to, ≥1 prior line of standard treatment in the recurrent or metastatic setting. Patients were also required to have measurable disease defined by Response Evaluation Criteria In Solid Tumors V.1.1 (RECIST V.1.1) and adequate performance status (Eastern Cooperative Oncology Group performance score of 0–1). To more objectively select patients with preserved performance status for enrollment into a phase I trial of a novel NDV, we limited enrollment to patients with adequate performance status using an established immunotherapy-specific prognostic score (GRIm-Score, score 0–1) based on screening laboratory values.42 Further inclusion criteria and key exclusion criteria are detailed in the online supplemental methods.
Objectives
The primary objective was to assess safety and tolerability, describe the dose-limiting toxicities (DLT), and determine the dose and schedule of administration of MEDI5395 in combination with durvalumab. Secondary objectives were to evaluate the preliminary efficacy of MEDI5395 administered at different dose levels in combination with durvalumab, and to determine the pharmacokinetics (viral genome copies in blood and GM-CSF plasma concentrations), pharmacodynamics (CD8+ T-cell infiltration and PD-L1 expression in tumors pre-dosing and post-dosing) and immunogenicity of MEDI5395. Exploratory objectives included assessment of MEDI5395 viral shedding, determination of the immunogenicity of GM-CSF and durvalumab, and biomarker assessments.
Assessments and statistical analyses
Safety and efficacy analyses were performed in the as-treated population, which included all participants who received ≥1 dose of any drug. Adverse events (AE) and laboratory anomalies were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events V.5.0. Further details regarding safety assessments are provided in the online supplemental methods. ORR, disease control rate (DCR), time to response (TTR), and duration of response (DoR) were based on RECIST V.1.1. For ORR and DCR, 95% CIs were calculated using the exact probability method. TTR and DoR were evaluated using the Kaplan-Meier method. Planned evaluation of progression-free survival and overall survival did not occur due to the early termination of the study for non-safety-related reasons.
For pharmacokinetic assessments, results from reverse transcription-quantitative PCR (RT-qPCR) to determine genome copies of MEDI5395 in whole blood and immunoassay to determine GM-CSF protein concentrations in plasma (Meso Scale Diagnostics, Rockville, Maryland, USA) were summarized by dose cohort along with descriptive statistics. Viral infectivity was determined by a cell-based fluorescent-focus assay43 for selected whole blood samples that had detectable MEDI5395 genome copies.
For pharmacodynamic assessments, immune activation in the tumor microenvironment was assessed by measuring changes in CD8+ T-cell infiltration and PD-L1 expression in the tumor pre-dosing and post-dosing with MEDI5395 using matched pairs of tumor specimens obtained at screening and on-treatment (at MEDI5395 dose 4). CD8+ cells within the designated tumor area were reported as cell density (number of positive cells per mm2). PD-L1 expression was evaluated as an estimated percentage of positivity in TC (score). The differences in CD8+ T-cell infiltration and PD-L1 expression at baseline grouped by best overall response were calculated using the Wilcoxon signed-rank test. The statistical significance was set at 0.05. Data was analyzed and plotted using R V.4.3.1.
Immunogenicity of MEDI5395 was assessed by summarizing the number and percentage of participants who developed detectable anti-MEDI5395 neutralizing antibodies (nAb). nAbs were measured by a cell-based NDV neutralization assay and reported as log2IC50. IC50 (50% inhibitory concentration) was determined as the reciprocal of the serum dilution that resulted in 50% virus neutralization.
Viral shedding in saliva and urine was assessed by measuring genome copies of MEDI5395 pre-MEDI5395 and post-MEDI5395 administration using RT-qPCR assay. For samples with detectable MEDI5395 genome copies (shedding samples), viral infectivity was then determined to evaluate whether a live virus was being shed. The percentage of participants with detectable MEDI5395 virus in urine and saliva was summarized by dose cohort. RT-qPCR was used to detect MEDI5395 genome in tumor biopsies.
Plasma cell-free DNA samples were analyzed using next-generation sequencing assays (Guardant Health, GuardantOMNI 500-gene panel). Genomic alterations were identified using Guardant Health’s pipeline as previously described.44 45 Gene expression levels were detected using RNA sequencing and the Wilcoxon test was used to compare gene expression levels (log-transformed transcripts per million) between time points (pretreatment vs post-treatment) (see online supplemental methods for further details). Change in maximum variant allele frequency was calculated for each sample from baseline using only somatic variants. A reduction of 50% was considered a potentially meaningful measurement of tumor shedding.
Results
Patients
Of the 60 patients who consented to the study across two UK sites and eight US sites, 21 were screen failures (n=15 did not meet inclusion/exclusion criteria; n=4 withdrew consent; n=2 other), while 39 were assigned to and received treatment with MEDI5395. At study entry, the 39 enrolled patients had a median age of 63.0 years and 69.2% were men. Most patients (38/39; 97.4%) had stage IV disease, and over half (22/39; 56.4%) had received ≥4 prior lines of standard therapy (median prior number of treatments 4 (range 1–8)). 29 patients (29/39; 74.4%) had received prior ICIs, most commonly pembrolizumab (15/39; 38.5%) or nivolumab (13/39; 33.3%) (online supplemental table 1). 34 patients (34/39; 87.2%) completed all six doses of MEDI5395 prior to the date of data cut-off (November, 2021). Five patients (5/39; 12.8%) discontinued MEDI5395, due to the patient’s decision (3/39; 7.7%), an AE (MEDI5395-related Grade 3 fatigue in Cohort 1B; 1/39; 2.6%), and the investigator’s decision (1/39; 2.6%).
39 patients were allocated to treatment with durvalumab. Three patients (3/39; 7.7%) discontinued MEDI5395 prior to commencing treatment with durvalumab. 36 patients (36/39; 92.3%) received treatment with durvalumab, including two who discontinued MEDI5395. All 36 of these patients discontinued durvalumab treatment, due to progressive disease in 27/36 (75.0%) patients, patient choice in 2/36 (5.6%) patients, death (unrelated to study drug) in 1/36 (2.8%) patients, and other in 6/36 (16.7%) patients (defined as entering the continued treatment period, in which patients continued to receive durvalumab after leaving the original study).
All 39 (100%) patients discontinued the study by the data cut-off date, due to death (14/39; 35.9%), patient decision (3/39; 7.7%), loss to follow-up (2/39; 5.1%) or other (20/39; (51.3%), including 14/39 (35.9%) who were in survival follow-up and 6/39 (15.4%) who entered the continued treatment period at the time the study ended).
Safety and tolerability
Among the 39 evaluable patients, the mean duration of MEDI5395 exposure was 17.7 days (SD 4.3 days) and the mean number of MEDI5395 administrations was 5.4 (SD 1.3). Among the 36 patients who received durvalumab, 21/36 (58.3%) received durvalumab for ≥2 months and 3/36 (8.3%) received durvalumab for ≥6 months. The median number of durvalumab cycles was 3 (range 1–13).
All 39 patients experienced at least one treatment-emergent AE (TEAE), with 35/39 (89.7%) and 8/39 (20.5%) patients experiencing a TEAE that was considered related to MEDI5395 or durvalumab, respectively. The most common TEAEs were fatigue (24/39; 61.5%), nausea (21/39; 53.8%), and chills (20/39; 51.3%) (online supplemental table 2). Of interest, MEDI5395-related IRRs were observed in 8/39 (20.5%) patients (including one instance of Grade 3 IRR) and MEDI5395-related hepatotoxicity events were aspartate aminotransferase increased in 3/39 (7.7%) patients, alanine aminotransferase increased in 2/39 (5.1%) patients, blood alkaline phosphatase increased in 1/39 (2.6%) patients, and gamma-glutamyltransferase increased in 1/39 (2.6%) patients (Grade 3). Grade 3–4 TEAEs were reported in 27/39 patients (69.2%); these were considered related to MEDI5395 in 12/39 patients (30.8%). Treatment-emergent serious AEs (SAEs) occurred in 16/39 patients (41.0%); 3/39 (7.7%) patients experienced an SAE that was considered related to MEDI5395. No durvalumab-related SAEs were reported. MEDI5395-related SAEs included exacerbation of Grade 3 chronic obstructive pulmonary disease (n=1) in Cohort 2A, Grade 3 IRR (n=1) in Cohort 3A, and Grade 1 atrial fibrillation (n=1) in Cohort 3B. No Grade 5 TEAEs were reported.
Two patients experienced a DLT during the 28-day DLT-evaluation period. One patient had MEDI5395-related Grade 3 fatigue 1 day after the first dose (Cohort 1B), which did not resolve to Grade ≤2 within 5 days after administration and led to permanent discontinuation of MEDI5395. The second patient developed MEDI5395-related Grade 3 neutropenia on the day of the second dose and 2 days after the fifth dose of MEDI5395 (Cohort 3A), leading to the third and sixth doses of MEDI5395 being omitted. For both neutropenia events, the AE resolved after 8 days and 6 days, respectively. The maximum tolerated dose of MEDI5395 at the time of study termination was 1011 FFU (with 2 log desensitization for the first dose) with sequential durvalumab with 2 log desensitization for the first dose and 1010 FFU dose (with 1 log desensitization for the first dose) with delayed durvalumab.
Preliminary efficacy
Tumor response is summarized in online supplemental table 3 and figure 1. The ORR was 10.3% (4/39; 95% CI 2.9%, 24.2%) and the DCR was 30.8% (12/39; 95% CI 17.0%, 47.6%). Four patients (4/39; 10.3%) achieved a partial response (PR), including one patient in Cohort 1A with NSCLC, two patients in Cohort 3A backfill with NSCLC and head and neck squamous cell carcinoma (HNSCC), respectively, and one patient in Cohort 3B with HNSCC. Three of the four patients achieving PR had received prior anti-PD-1 ICIs (nivolumab or pembrolizumab), while the remaining patient had received chemotherapy (online supplemental table 4). There was no evidence of a MEDI5395 dose response, as illustrated in figure 1. The median TTR in patients with an objective response was 1.7 months (95% CI 1.1, not calculated); DoR ranged from 1.9 to 5.6 months (data not shown).
Percentage change from baseline in target lesion sum of diameters by cohort (as-treated population). EOT, end of treatment.
Pharmacokinetics
Whole blood viral genome concentrations of MEDI5395 for the DLT evaluation period are presented by dose cohort (online supplemental figure 2A) and at 120 days (online supplemental figure 2B) after administration of the first MEDI5395 dose. A tendency to dose-dependent pharmacokinetics of the viral genome was observed in whole blood. Approximately 67% (6/9) of patients treated with MEDI5395 108 FFU had detectable viral genome peripherally, while all participants treated with MEDI5395 109 FFU and above had detectable viral genome peripherally. Viral genome levels in whole blood were generally detected in samples collected from the end of the first infusion, increased after each subsequent dose, and remained detectable for the whole extensive sampling schedule from the first dose through to 7 days after dose 6. In general, quantifiable samples were observed in subsequent cycles for up to approximately 30 days after the last MEDI5395 dose (online supplemental figure 2). Exposure to the MEDI5395 viral genome lasted approximately 13–51 days and increased with increasing dose levels. Following repeat administration of MEDI5395, the median time to maximum observed concentration (tmax) for MEDI5395 was observed between the second and sixth dose (between 3.1 and 15.1 days after the first dose) (online supplemental table 5). Cumulative peak exposure (maximum observed concentration from the administration of the first dose of MEDI5395 through 168 hours after the sixth dose) and extent of exposure (area under the concentration time curve from 0 to the last quantifiable concentration) increased with increasing dose level over the tested range. Cumulative exposure was comparable for both sequential and delayed dose cohorts (online supplemental table 5). No infectious titer was found in tested whole blood samples.
Detectable plasma GM-CSF was reported for only seven samples from five patients, all of whom were treated at dose levels of 1010 or 1011 FFU. Concentration levels up to 6.4 pg/mL were observed at the end of infusion from the second dose administration (data not shown); and baseline values for plasma GM-CSF were below the lowest limit of quantification (2.15 pg/mL).
Pharmacodynamics
Evaluable pretreatment and on-treatment samples for pharmacodynamic evaluation were available for 20 patients from all dose cohorts except Cohort 1A, including 15 patients from the sequential and five patients from the delayed cohorts. Although seven patients showed a ≥50% increase in CD8+ cell density and five patients showed a ≥50% increase in PD-L1 expression, there was no clear trend regarding the change in PD-L1 expression or in tumorous CD8+ cell density, in the overall population by response status, dose level or histology (figure 2A). However, tumors from patients with disease control (tumor response of stable disease or PR) had significantly greater PD-L1 expression and tumorous CD8+T cells at baseline than those who experienced disease progression (figure 2B).
CD8+ cell density and PD-L1 expression in pretreatment (screening) versus on-treatment (dose 4) tumor biopsies (A), and pretreatment CD8+ cell density and PD-L1 expression by BOR (B). In (A), solid lines depict a ≥50% change in CD8+ cell density and PD-L1 expression from baseline, whereas dotted lines represent any change lower than 50%. In (B), **p<0.01. Horizontal bar denotes the median; boxes range from 25th to 75th percentile; whiskers extend to the lowest and highest values. BOR, best overall response; CD8, cluster of differentiation 8; NE, not evaluable; PD, progressive disease; PD-L1, programmed cell death-ligand 1; PR, partial response; SD, stable disease.
Immunogenicity
Baseline nAb data were available for all 39 patients. Seven (17.9%) patients were positive for MEDI5395 nAbs at baseline; however, these patients had a very low median titer of 4.0 log2IC50, which was close to the lower limit of quantification (3.32 log2IC50) and may be due to non-specific inhibition from individual serum samples (online supplemental table 6). Post-baseline nAb data were available for 38 patients (one patient in Cohort 3A backfill had no post-baseline data). nAbs were induced in all 38 patients with a median maximum titer of 10.0 log2IC50 (range 6.0–13.0). The post-baseline titers were comparable between patients who were nAb positive (n=7) or negative (n=31) at baseline, with a median maximum titer of 11.0 log2IC50 (range 9–13) and 10.0 log2IC50 (6.0–13.0), respectively. All patients were persistently positive (defined as nAb-positive at ≥2 post-baseline assessments with ≥16 weeks between the first and last assessment or positive at the last post-baseline assessment), maintaining a high level of nAbs up to 90 days post last MEDI5395 dose. Of the four patients who achieved a PR, one was nAb-positive and three were nAb-negative at baseline. All four patients developed high nAb titers above the baseline value, which were comparable to the post-baseline titers observed across the overall population.
Viral shedding
A tendency to dose-dependent viral shedding was observed in saliva and urine (online supplemental figure 3). Approximately 44% of patients treated with MEDI5395 108 FFU had at least one detectable viral genome sample, while at least 80% of patients treated with MEDI5395 109 or 1010 FFU, and all patients treated at the MEDI5395 1011 FFU had detectable viral genome. Following repeat administration of MEDI5395, the median tmax was generally observed between the first and fourth dose (between 0.1 and 9.2 days after the first dose). For viral shedding in saliva, viral genome was immediately detected at the end of the infusion of MEDI5395. Levels of viral genome tended to increase to a similar peak level after each dose and generally fell below the detectable level within 24 hours after the last dose. Viral genome levels in saliva were detected over a span of approximately 8–17 days and increased with increasing dose level. Infectious titers were found in one patient each in Cohorts 3A backfill and 1B and were in the range of 3.81–4.06 log10 FFU/mL.
Following treatment with MEDI5395 108 FFU, no patients had detectable viral genome in their urine. Approximately 70% of participants treated with MEDI5395 109 or 1010 FFU, and all patients treated at 1011 FFU, had detectable viral genome in their urine. Following repeat administrations of MEDI5395, the median tmax was observed after the sixth dose (between 17.0 and 24.4 days after the first dose). Overall, viral genome was detected in fewer than half of patients treated with MEDI5395, and generally only after the sixth dose. Viral genome was detectable in some patients up to approximately 30 days after the last dose. Viral genome levels were generally detected over a span of approximately 4–15 days and increased with increasing dose level. Infectious titers were found in seven patients in the 109 and 1010 FFU dose cohorts, and were in the range of 3.47–3.92 log10 FFU/mL.
Biomarker assessment
Systemically administered MEDI5395 genome was detected in the tumor biopsies of 6/20 patients (figure 3A). While not all patients had detectable virus in blood, 5/9 patients had an increased type I IFN response signature indicating the promotion of an innate immune response (figure 3B).
MEDI5395 viral copies (A) and type I IFN response signature (indicating antiviral immune response) (B) in tumor cells pretreatment (screening) and post-treatment (dose 4). *p<0.05. IFN, interferon; PD, progressive disease; PR, partial response; SD, stable disease; TPM, transcript per million.
Though increases in the expression of cytotoxic T cell and IFN-inducible genes (representing immune activation), as well as upregulation of gene signatures associated with antitumor response (CD8, IFN-γ, activated natural killer, and Th1) in the tumor microenvironment were observed, these were not statistically significant for the overall population (figure 4A,B). Systemic IFN-γ levels remained independent of MEDI5395 dose (figure 5). To evaluate if viral replication led to the generation of GM-CSF transgene or other downstream markers of peripheral immune activation, individual genes downstream of immune activation, including CSF2 (encoding GM-CSF) and CXCL9/10/11 were analyzed. This biomarker analysis showed that treatment with MEDI5395 had no effect on the expression of CSF2 or other genes associated with an antitumor response after the fourth dose compared with baseline (figure 6).
Expression of immune activation genes in the tumor microenvironment (A) and gene signatures associated with antitumor response (B) pretreatment (screening) and at dose 4 of MEDI5395. Horizontal bar denotes the median; boxes range from 25th to 75th percentile; whiskers extend to the lowest and highest values. CD8, cluster of differentiation 8; IFN-(γ), interferon (gamma); NK, natural killer; PD, progressive disease; PR, partial response; SD, stable disease; Th1, type 1 T helper cell; TPM, transcript per million.
Systemic IFN-γ levels after each dose of MEDI5395 and durvalumab in the sequential (A) and delayed (B) dosing regimens. Solid lines indicate the median concentrations per cohort while the shaded areas represent the 95% CI around the median when n>1. C, cycle; D, day; Durva, durvalumab; IFN-γ, interferon-gamma.
Expression of antitumor response genes pretreatment (screening) and at dose 4 of MEDI5395. PD, progressive disease; PR, partial response; SD, stable disease.
Furthermore, a few patients (3/4 who achieved PR and 3/7 who had the stable disease) showed a potentially meaningful reduction in maximum variant allele frequency measurement of tumor shedding (ie, ≥50% reduction from baseline) (figure 7).
Change in variant allele frequency from baseline by BOR. BOR, best overall response; C, cycle, D, dose; durva, durvalumab; PD, progressive disease; PR, partial response; SD, stable disease; VAF, variant allele frequency.
Discussion
We report on a phase I, first-in-human study of MEDI5395, a recombinant NDV encoding a GM-CSF transgene, in combination with durvalumab in patients with advanced treatment-refractory tumors. In the dose-escalation phase, we evaluated four planned, ascending dose levels of MEDI5395 (108, 109, 1010, and 1011 FFU) with either sequential or delayed durvalumab. Overall, the safety profile of MEDI5395 in combination with durvalumab was tolerable with a low (3/39; 7.7%) incidence of MEDI5395-related SAEs. The observed SAEs were generally transient, and did not preclude further MEDI5395 dosing or treatment with durvalumab. The maximum tolerated dose (MTD) of MEDI5395 at the time of study termination was 1011 FFU (with 2 log desensitization for the first dose) with sequential durvalumab and 1010 FFU (with 1 log desensitization for the first dose) with delayed durvalumab.
Based on the mechanism of action of MEDI5395 and preclinical toxicology studies, hepatotoxicity and IRRs were anticipated with MEDI5395.36 37 However, the observed incidence of MEDI5395-related hepatotoxicity or IRRs were infrequent and low grade. Two patients experienced DLTs, both of which were considered related to MEDI5395; however, neither triggered a de-escalation decision because they occurred in different cohorts. Analysis of the MTD was not completed in the delayed dosing regimen due to early study termination. However, as the number of DLTs was low and every cohort passed DEC review and was considered tolerated, there was no indication that the MTD had been reached. Overall, the nature and frequency of TEAEs and MEDI5395-related AEs were consistent with the safety profile of MEDI5395, and were not impacted by sequential or delayed durvalumab. The relatively short period of durvalumab exposure prior to data cut-off likely contributed to the low number of durvalumab-related TEAEs. No new safety signals were identified for either MEDI5395 or durvalumab.
39 patients were assigned to and received treatment with MEDI5395; 34 (34/39; 87.2%) completed all six doses of MEDI5395, and 36 (36/39; 92.3%) received durvalumab treatment, including two who discontinued MEDI5395. Limited evidence of preliminary antitumor activity was observed in this study, with four patients achieving a PR (two with HNSCC and two with NSCLC), three of whom had prior progression on anti-PD-1 therapy. These patients were enrolled in Cohorts 1A (n=1), 3A backfill (n=2), and 3B (n=1). No evidence of a MEDI5395 dose response was observed. It should be noted that many patients were heavily pretreated before entering the study, with over half having received ≥4 prior therapies.
Despite the small sample size, a trend towards dose-dependent pharmacokinetics of the MEDI5395 viral genome was observed in whole blood, with increasing genome copy levels occurring at higher dose levels. There was also a trend towards dose-dependent viral shedding observed in saliva and urine following repeat administration of MEDI5395 alone or together with durvalumab. However, virus shedding from saliva and urine was transient and occurred at low levels, suggesting that it is unlikely to raise environmental safety concerns.
We present proof of concept data that NDV could be isolated in the tumor after systemic administration, independent of MEDI5395 dose level. Response to combination therapy with T-VEC and an anti-PD-1 ICI has been associated with increased CD8+T cells, elevated PD-L1 protein expression, as well as IFN-γ gene expression.30 Changes in the expression of cytotoxic T cell and IFN-inducible genes in the tumor microenvironment were observed in some patients but were not significant for the overall population. However, given the limited number of patients with clinical benefit, it is unclear whether the lack of uniform increase in immune activation was related to limited delivery of MEDI5395 to the tumors, tumor resistance to MEDI5395 replication, or limited intratumoral immune response to MEDI5395. Patients who achieved a PR or who had stable disease tended to have higher baseline PD-L1 and CD8+ levels in their tumor tissue, which might suggest a greater potential for response to MEDI5395 in such patients. This is consistent with the improved response to standard ICI antibodies observed in patients with high levels of tumor-infiltrating lymphocytes and increased PD-L1 expression.20 46 47
Few patients showed potentially meaningful reduction (≥50%) in maximum variant allele frequency measurement of tumor shedding. The burden of administering MEDI5395 up to three times a week required significant cooperation from both participants and sites, and likely contributed to the variability in duration of exposure to MEDI5395.
Immunogenicity data derived from pre-dosing and post-dosing with MEDI5395 demonstrated rapid development of nAbs following treatment in all patients, however, there was no indication that the presence of nAbs (pre-existing or post-therapy) negatively impacted MEDI5395 efficacy, particularly since systemic NDV genome levels remained high after each dose. In our study, one patient with anti-MEDI5395 nAbs at baseline still achieved a PR following study treatment. This is consistent with a previous study where patients with metastatic solid tumors who demonstrated baseline nAbs were able to achieve stable disease following intravenous infusion of an oncolytic poxvirus, with no correlation observed between baseline antibody titer and antitumor activity.48 Preclinical studies with intratumoral NDV demonstrated that pre-existing immunity to NDV may actually potentiate the antitumor response and therapeutic efficacy. In addition, preclinical studies of reovirus immunovirotherapy have suggested that preconditioning with cytokines may enhance virus-mediated antitumor activity.49 Further studies will be needed to determine the impact of anti-vector immunity on therapeutic efficacy in patients.
In conclusion, the overall results of this study provide proof-of-concept information, and the feasibility, safety, preliminary efficacy, pharmacokinetics, pharmacodynamics, immunogenicity, and viral shedding of oncolytic recombinant NDV administered systemically in combination with durvalumab. Systemically administered MEDI5395 and durvalumab increased cytotoxic T cell and IFN-inducible gene expression in patients, independent of dose level and timing of durvalumab. Further development has been truncated to facilitate the prioritization of other NDV assets.
Supplemental material
Data availability statement
Data are available upon reasonable request. Data underlying the findings described in this manuscript may be obtained in accordance with AstraZeneca’s data sharing policy described at: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure. Data for studies directly listed on Vivli can be requested through Vivli at www.vivli.org. Data for studies not listed on Vivli could be requested through Vivli at https://vivli.org/members/enquiries-about-studies-not-listed-on-the-vivli-platform/. The AstraZeneca Vivli member page is also available outlining further details: https://vivli.org/ourmember/astrazeneca/.
Ethics statements
Patient consent for publication
Ethics approval
The institutional review board/independent ethics committee responsible for each participating site reviewed and approved the final study protocol. The study was performed in accordance with ethical principles that have their origin in the Declaration of Helsinki and are consistent with International Council for Harmonization/Good Clinical Practice, and applicable regulatory requirements. South Central – Oxford A Research Ethics Committee - 19/SC/0405/IRAS263137; Mayo Clinic Institutional Review Board - 19-003080; University of Pittsburgh Human Research Protection Office - STUDY19060103; UCSD Human Research Protections Program - #190258; Roswell Park, Comprehensive Cancer Center Institutional Review Board - STUDY00000957/P-82519; Memorial Sloan-Kettering Institutional Review Board - #20-048; Lifespan Research Protection Office - 201820UNC IRB - 19-2119. Participants gave informed consent to participate in the study before taking part.
Acknowledgments
Medical writing support for the development of this manuscript, under the direction of the authors, was provided by Abigail Marmont, PhD, of Ashfield MedComms, an Inizio company, and was sponsored by AstraZeneca. DD is supported by the following: NIH/NCI U01 CA271407, R01 CA257265, Gateway Foundation for Cancer Research.
References
Supplementary materials
Supplementary Data
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Footnotes
X @diwakardavar
Contributors Guarantor: DD. DD: Study design, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. BAC: Analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. GKD: Study design, data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. SS: Study design, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. MJB: Study design, data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. KJH: Study design, data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. SPP: Data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. EG: Data collection; draft manuscript preparation; and approval of the final version of the manuscript. AS: Data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. SA: Analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. ZC: Data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. CF: Data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. MG: Analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. JBu: Study design, data collection; draft manuscript preparation; and approval of the final version of the manuscript. ET: Data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. ND: Analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. KL: Study conception and design; data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. FA: Analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript. DZ: Study design, data collection, analysis and interpretation of the results; draft manuscript preparation; and approval of the final version of the manuscript.
Funding This study was funded by AstraZeneca (Grant/award number N/A). Study number: D6450C00001 (https://www.astrazenecaclinicaltrials.com/).
Competing interests DD reports Grants/Research Support (institutional) from Arcus, CellSight Technologies, Immunocore, Merck, Regeneron Pharmaceuticals, Tesaro/GSK; Consultant fees from ACM Bio, Ascendis Pharma, Clinical Care Options (CCO), Gerson Lehrman Group (GLG), Merck, Medical Learning Group (MLG), Xilio Therapeutics. CE Speakers’ Bureau from Castle Biosciences; reports Intellectual Property for US Patent 63/124,231, “Compositions and Methods for Treating Cancer”, December 11, 2020; US Patent 63/208,719, “Compositions and Methods For Responsiveness to Immune Checkpoint Inhibitors (ICI), Increasing Effectiveness of ICI and Treating Cancer”, June 9, 2021. BAC reports Institutional Research Support from AstraZeneca, AbbVie, Actuate Therapeutics, Astellas, Agenus, Bayer, Dragonfly Therapeutics, Mink Therapeutics, Pfizer, Pyxis Oncology, Repare Therapeutics, Regeneron; Advisory Boards for Seattle Genetics. GKD reports Consulting Fee from Amgen, AstraZeneca, Bayer, Eli Lilly, Janssen, Meru, Mirati, Novartis, Regeneron. SS reports Employment from University of North Carolina; Honoraria from Naveris, Exelixis, Eisai, Medscape, Association of Community Cancer Centers; Consulting fees from Exelixis. Grants or Funds from Merck, AstraZeneca, Exelixis, Regeneron, Inovio, ASCO. MJB reports Grants, Funds, Trial support to institution (Mayo Clinic). KJH reports Scientific Advisory Board Membership for Oncolys, PsiVac, Replimune (paid to institution); Consulting Fees for PsiVac, Replimune, VacV (paid to institution); Grants or Funds from Replimune (paid to institution). SPP reports Consulting Fees from Amgen, AstraZeneca, BeiGene, Bristol-Myers Squibb, Certis, Eli Lilly, Jazz, Genentech, Illumina, Merck, Pfizer, Signatera, Tempus; Grants or Funds (research funding to university) from Amgen, AstraZeneca, A2bio, Bristol-Myers Squibb, Eli Lilly, Fate Therapeutics, Gilead, Iovance, Merck, Pfizer, Roche/Genentech. EG reports Consulting Fee from Kiyatec (personal compensation), Karyopharm Therapeutics (Data Safety Monitoring Board, compensation to employer), Boston Scientific (Data Monitoring Committee, compensation to employer), Servier Pharmaceuticals (Advisory Board, compensation to employer), Boehringer Ingelheim (Advisory Board, compensation to employer); Grants or Funds from Servier Pharmaceuticals (formerly Agios Pharmaceuticals), Denovo Biopharma, Celgene, MedImmune. AS reports Consulting fees from Roche and Chugai; Academic grants from Replimune, Histosonics, Oncolytics Biotech, Transgene (all paid to institution). SA: AstraZeneca employee and stock holder. ZC reports no potential conflict of interest. CF: AstraZeneca employee and stock holder. MG: AstraZeneca employee and stock holder. JBu: AstraZeneca employee and stock holder. ET: AstraZeneca employee and stock holder. ND: AstraZeneca employee and stock holder. KL: AstraZeneca employee and stock holder. FA: AstraZeneca employee and stock holder. DZ reports Institutional Grants from Merck, Genentech, AstraZeneca, Plexxikon, and Synthekine; Personal Fees; AstraZeneca, Xencor, Memgen, Takeda, Synthekine, Immunos, Tessa Therapeutics, Miltenyi, and Calidi Biotherapeutics. DZ is a holder of a patent on use of oncolytic NDV for cancer therapy (unrelated to the agent under study).
Provenance and peer review Not commissioned; externally peer reviewed.
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