Kreider, Brent L.

Abstract Purpose: Intratumoral injection of Clostridium novyi-nontoxic (C. novyi-NT), lacking alpha-toxin, germinates and subsequently replicates in the tumor hypoxic regions, causing cell lysis and inflammation. This phase Ib study investigated the safety and synergistic effects of pembrolizumab and C. novyi-NT in advanced solid tumors. Patients and Methods: Patients with injectable solid tumors received one intratumoral C. novyi-NT injection (day 8) across four dose cohorts (3 × 104 to 100 × 104 spores) with pembrolizumab (200 mg intravenously every 3 weeks, day 0–24 months). Sixteen patients were enrolled with a median age of 62.5 years, and the most common tumor types were breast cancer and melanoma. Results: The combination therapy demonstrated a manageable safety profile, with one grade 3 dose-limiting toxicity of abscess formation and the remainder of treatment-related adverse events in ≥10% of patients being grade 1 or 2 injection site reaction (25%), pyrexia (19%), pruritus (13%), leukopenia (13%), and anemia (13%). The maximum tolerated dose was determined to be pembrolizumab intravenously at 200 mg every 3 weeks and a single dose of 100 × 104C.novyi-NT spores intratumorally on day 8. The confirmed overall objective response rate of 25% was observed among four patients with nonkeratinizing undifferentiated nasopharyngeal squamous carcinoma, human papilloma virus–positive squamous cell carcinoma of the base of the tongue, vulvar melanoma, and chordoma. Among these patients, we obtained three partial responses and one complete response. The median duration of the response was 10.93 months, and stable disease was observed in 69% of patients. Conclusions: This study highlights the potential of the C. novyi-NT and pembrolizumab combination as a promising therapeutic strategy for treatment-refractory solid tumors.

Abstract Purpose: Intratumorally injected Clostridium novyi-NT (nontoxic; lacking the alpha toxin), an attenuated strain of C. novyi, replicates within hypoxic tumor regions resulting in tumor-confined cell lysis and inflammatory response in animals, which warrants clinical investigation. Patients and Methods: This first-in-human study (NCT01924689) enrolled patients with injectable, treatment-refractory solid tumors to receive a single intratumoral injection of C. novyi-NT across 6 dose cohorts (1 × 104 to 3 × 106 spores, 3+3 dose-escalation design) to determine dose-limiting toxicities (DLT), and the maximum tolerated dose. Results: Among 24 patients, a single intratumoral injection of C. novyi-NT led to bacterial spores germination and the resultant lysis of injected tumor masses in 10 patients (42%) across all doses. The cohort 5 dose (1 × 106 spores) was defined as the maximum tolerated dose; DLTs were grade 4 sepsis (n = 2) and grade 4 gas gangrene (n = 1), all occurring in three patients with injected tumors >8 cm. Other treatment-related grade ≥3 toxicities included pathologic fracture (n = 1), limb abscess (n = 1), soft-tissue infection (n = 1), respiratory insufficiency (n = 1), and rash (n = 1), which occurred across four patients. Of 22 evaluable patients, nine (41%) had a decrease in size of the injected tumor and 19 (86%) had stable disease as the best overall response in injected and noninjected lesions combined. C. novyi-NT injection elicited a transient systemic cytokine response and enhanced systemic tumor-specific T-cell responses. Conclusions: Single intratumoral injection of C. novyi-NT is feasible. Toxicities can be significant but manageable. Signals of antitumor activity and the host immune response support additional studies of C. novyi-NT in humans.

Abstract Bacteriolytic strategies offer unique advantages to combat a broad range of cancers often refractive to conventional chemotherapies and/or radiotherapies. C. novyi-NT is an attenuated strain of Clostridium novyi, a spore-forming, gram-positive, obligate anaerobe that lacks a lethal alpha- toxin, expressed by the parental strain. When administered intravenously or intratumorally with percutaneous injection, C. novyi-NT colonizes and replicates within the hypoxic region of the tumors, eliciting robust, tumor-confined cell lysis. In this first-in-man phase 1 study, patients with injectable treatment-refractory solid tumors received a single intratumoral injection of C. novyi-NT spores across 6 dose cohorts (spore concentrations of 104, 3x104, 105, 3x105, 106, 3x106) using a 3+3 trial design. The primary endpoints were to assess the safety profile, the dose limiting toxicity, and the maximum tolerated dose of C. novyi-NT. Key secondary endpoints included assessments of the preliminary antitumor activity of the injected tumor, an overall response evaluated by RECIST v. 1.1, and the host immune and inflammatory response to C. novyi-NT. Twenty-four patients were enrolled between November, 2013 and April, 2017. A single intratumoral injection of C. novyi-NT led to germination and resultant tumor lysis of injected tumor masses in 46% of patients across all dosing cohorts. The cohort 5 dose of 106 spores was defined as the maximum tolerated dose. Dose-limiting toxicities were grade 4 sepsis and grade 4 gas gangrene (n=1), all in patients with germination. In the 22 evaluable patients, 21 (95%) had stable disease (SD) as the best response for the injected lesion (tumor shrinkage of > 10% was observed in 21% of patients) and 19 (86%) had overall SD as the best response per RECIST 1.1. C. novyi-NT injection resulted in transient serum cytokine responses consistent with inflammasome activity, activation of innate immunity, tissue remodeling, and angiogenesis. Tumor antigen specific ELISPOT assays pre- and post- treatment documented enhanced secretion of IFNγ and TNFα by circulating T-cells, indicating improved systemic tumor specific T-cell responses. Multiparametric in situ immunostaining of core biopsies suggested improved immune cell infiltration in metastatic lesions. These early signs of improved antitumor activity in patients with advanced solid tumors have encouraged a new trial of C. novyi-NT in combination with immune checkpoint inhibitors. Citation Format: Filip Janku, Mrinal Gounder, Abdul Mohammad Pezeshki, Ravi Murthy, Andrea Wang-Gillam, Dale Shepard, David S. Hong, Sarina A. Piha-Paul, Anjali Raina, Alexey A. Leontovich, Gary DeCrescenzo, Brent L. Kreider, David Tung, Mary Varterasian, Halle H. Zhang, Khashayarsha Khazaie. First-in-man clinical trial of intratumoral injection of Clostridiumnovyi-NT spores in patients with treatment-refractory advanced solid tumors: Safety, activity, and immune responses [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A011.