A first-in-human phase 1 study of cavrotolimod, a TLR9 agonist spherical nucleic acid, in healthy participants: Evidence of immune activation

IntroductionTumor immunotherapy is designed to control malignancies through the host immune response but requires circumventing tumor-dysregulated immunomodulation through immunostimulation, relieving immunorepression, or a combination of both approaches. Here we designed and characterized cavrotolimod (formerly AST-008), an immunostimulatory spherical nucleic acid (SNA) compound targeting Toll-like receptor 9 (TLR9). We assessed the safety and pharmacodynamic (PD) properties of cavrotolimod in healthy participants in a first-in-human Phase 1 study under protocol AST-008-101 (NCT03086278; https://clinicaltrials.gov/ct2/show/NCT03086278).MethodsHealthy participants aged 18 to 40 years were enrolled to evaluate four dose levels of cavrotolimod across four cohorts. Each cohort included four participants, and all received a single subcutaneous dose of cavrotolimod. The dose levels were 5, 10, 12.5 and 18.8 µg/kg.Results and discussionCavrotolimod was well tolerated and elicited no serious adverse events or dose limiting toxicities at the doses tested. The results demonstrated that cavrotolimod is a potent innate immune activator, specifically stimulating Th1-type immune responses, and exhibits PD properties that may result in anti-tumor effects in patients with cancer. This study suggests that cavrotolimod is a promising clinical immunotherapy agent

505 Relationship of infusion duration and dose to safety, efficacy and pharmacodynamics: second part of a phase 1–2 study using VSV-IFNβ-NIS (VV1) oncolytic virus in patients with refractory solid tumors

BackgroundOncolytic viruses (OVs) show significant potential for treating tumors alongside immunotherapies.1 VV1 is an OV derived from the innocuous vesicular stomatitis virus (VSV). VV1 has been engineered to expresses human interferon (IFN) β and thyroidal sodium iodide symporter (NIS).2 VV1-infected cells produce IFNβ, which protects non-cancer cells from VV1 and allows VV1 to spread more efficiently in cancerous tissue.3 4 NIS expression on cells imports 99mTc pertechnetate, which facilitates in vivo imaging of virus infection.2 This three-part, phase 1–2 study was designed to determine the safety and tolerability of VV1 in patients with advanced unresectable and metastatic solid tumors. Here we report on the second part of this study: selection of recommended phase 2 regimen (RP2D), comprising further assessment of both duration and dose.MethodsPatients (n=29) were enrolled to receive a single IV infusion of VVI monotherapy. 23 patients received IV VV1 1.7 x1010 TCID50 over 15, 30, 60 or 180 min. Six patients received 1.0 x1011 TCID50 over 30 min with aggressive premedication and fluid support overnight. Patients were monitored for dose limiting toxicities over 21 days with efficacy assessments after 6 weeks and then every 3 months for survival. The primary objective was to establish the safety and tolerability of IV VV1. Secondary objectives included preliminary efficacy, pharmacokinetics and pharmacodynamics.ResultsIn this study VV1, demonstrated an acceptable safety profile. No deaths or Grade 4 infusion-related reactions (IRR) were reported. VV1 shedding by buccal swabs was negative at all study visits. Peak IFNβ serum levels and preliminary efficacy signals (2 PRs) were associated with 30 min infusion duration and higher dose, with RECIST data pending for 1 x 1011(table 1).Abstract 505 Table 1ConclusionsIn this study, the absence of viral shedding demonstrates that VV1 is safe for patient and caregiver with little/no environmental impact. There was no difference in safety between the lower and the higher dose infusions. In this patient population acceptable tolerability was observed at the higher dose with 30 min duration, thus the RP2D is 1x 1011 over 30 mins.Trial RegistrationNCT02923466ReferencesHemminki O, Dos Santos JM, Hemminki A. Oncolytic viruses for cancer immunotherapy. J Hematol Oncol 2020;13(1):84.Naik S, Nace R, Federspiel MJ, Barber GN, Peng KW, Russell SJ. Curative one-shot systemic virotherapy in murine myeloma. Leukemia 2012;26(8):1870–1878.Barber GN. Vesicular stomatitis virus as an oncolytic vector. Viral Immunol 2004;17(4):516–527.Lichty BD, Power AT, Stojdl DF, Bell JC. Vesicular stomatitis virus: re-inventing the bullet. Trends Mol Med 2004;10(5):210–216.Ethics ApprovalEthics approval was granted by WCG IRB. IRB tracking number: 20163005. Voluntary written informed consent was obtained from every patient prior to participation

Relationship of infusion duration to safety, efficacy, and pharmacodynamics (PD): Second part of a phase I-II study using VSV-IFNβ-NIS (VV1) oncolytic virus in patients with refractory solid tumors

3090 Background: VV1 (Voyager V1) is derived from VSV, an RNA virus with low human seroprevalence, engineered to replicate selectively in and kill human cancer cells. In Part 1 of this study, we demonstrated the safety of intratumoral VV1 and dose-response, using serum IFNβ as a biomarker; we observed viral replication in tumor and concomitant lymphocyte/neutrophil trafficking (SITC 2018). 2 other studies suggested greater efficacy and higher IFNβ levels with IV administration. Longer infusion durations were reported to mitigate infusion reactions (IRRs) for another oncolytic. Methods: We studied 3 different infusion durations of VV1 monotherapy at the recommended phase 2 IV dose (1.7 x 1010 TCID50) in patients with advanced solid tumors. Endpoints included safety, preliminary anti-tumor activity, viral titers, IFNβ PD and shedding. Patients received IV VV1 once on D1 and were monitored for DLT over 21 days with efficacy assessments every 6 weeks. IRRs were classified using Lee 2014 criteria for CRS as either constitutional symptoms only (G1) or involving hypotension (G2). Results: 18 patients were treated at 30, 60 and 180-minute durations (n = 7, 5 and 6, respectively). No DLTs, deaths or G3-4 related IRR AEs were observed. Most pts were female (67%), white (100%), with ECOG PS 0 (61%) and median 4 lines of prior systemic therapy (range 1-14) for colorectal (CRC; 56%), squamous cell carcinoma (11%), pheochromocytoma (11%), sarcoma (11%) or other (11%) cancers. The table shows results (number of patients) by infusion duration. Conclusions: There was no difference in safety between the 3 infusion durations, while efficacy and PD markers suggested better anti-tumor effect with 30-minute infusion. VV1 is safe for caregivers, with no viral shedding. Part 3 of this study will now treat CRC patients with VV1 in combination with a checkpoint inhibitor (avelumab). A 5-arm phase 2 basket study in combination with cemiplimab is proceeding with 30-minute infusions. Clinical trial information: NCT02923466 . [Table: see text

Abstract CT090: Rational design of an oncolytic virus permits use of interferon beta as a pharmacodynamic marker for clinical application

Abstract Introduction. Voyager-V1 (VV1) is an oncolytic vesicular stomatitis virus engineered to express human interferon beta (IFNβ) to enhance cellular antitumor immune responses and tumor selectivity. VV1 also contains the human sodium iodide symporter (NIS) as an imaging gene. We report here the novel use of virus-encoded IFNβ as a PD marker using correlative data from three Phase I trials of VSV-IFNβ-NIS in patients with refractory cancers (n=46). Methods. 46 patients with solid tumors (n=34) and hematological malignancies (n=12) received 1 dose of VV1 either intratumorally (ITu) or intravenously (IV) at doses ranging from 3 x 106 to 5 x 1010 TCID50. Plasma IFNβ levels were collected pre-treatment, 4 hours post-infusion, Day 2 (24-hour), Day 3, 8, 15 and 29 (IT only). Samples were processed using a standard IFNβ specific ELISA kit. Results. ITu dose escalation is complete with 27 patients treated and no DLTs. IV escalation is ongoing at 5 x 1010 TCID50 with 19 patients treated to date. In the ITu study, plasma IFNβ levels at 24h were undetected at the lowest dose levels (up to 1 x 107 TCID50), and became detectable from 3 x 107 TCID50. In the IV patients, IFNβ was detectable at all dose levels (5 x 109 through 5 x 1010 TCID50) with the highest peak and longest duration in a patient with metastatic endometrial cancer coincident with shrinkage of multiple tumors. The IFNβ produced by virus-infected cells can be differentiated from the acute innate antiviral responses by magnitude of response and AUC as the majority of the inflammatory cytokines returned to baseline by 48h. Peak IFNβ levels were variable between patients, likely reflecting heterogeneity in tumor susceptibility to VV1, ranging from 1.4pg/mL to 656pg/mL across 6 patients (mean 153pg/ml) at the highest ITu dose. Plasma IFNβ 24 hours post-therapy of >20pg/mL appears to predict for RECIST 1.1-evaluated SD vs PD, p=0.048 in the ITu patients. Peak IFNβ ranged from 18 to 1700 pg/mL across 9 patients (mean=442pg/ml) at 1.7 x 1010 in the IV study. Peak IFNβ was highest in two cases of endometrial cancer (1500 and 1700 pg/ml). The patient with the highest IFNβ levels on the IV trial showed 16.7% tumor shrinkage at the first tumor evaluation. SPECT imaging, which shows location of viral replication, was positive in 50% of ITu injected tumors, also validating of VV1 infection of target cells. To date, SPECT images were negative in the IV trial despite IFNβ positivity, reflecting IFNβ as a more sensitive PD marker of viral infection. IHC staining of tumor biopsies collected pre-treatment and 1 month after VSV showed increased numbers of CD3, CD8, CD68, PDL1 or PD1 in some injected or noninjected tumors. Other immune markers and tumor gene signatures are also being evaluated. Conclusions. Plasma IFNβ has emerged as a simple and convenient biomarker of viral replication in tumors. IFNβ will be used in future studies as a PD marker to assess the impact of immune-modulating combination drugs with VV1. Citation Format: Timothy P. Cripe, Jamie Bakkum-Gamez, Jaime R. Merchan, Martha Q. Lacy, Manish R. Patel, Steven Powell, James Strauss, Lianwen Zhang, Toshie Sakuma, Memy Diaz, Nandakumar Packiriswamy, Deepak Upreti, Bethany Brunton, Dragan Jevremovic, Stephen J. Russell, Alice Bexon, Kah-Whye Peng. Rational design of an oncolytic virus permits use of interferon beta as a pharmacodynamic marker for clinical application [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT090