Tilsotolimod Exploits the TLR9 Pathway to Promote Antigen Presentation and Type 1 IFN Signaling in Solid Tumors: A Multicenter International Phase I/II Trial (ILLUMINATE-101)

PURPOSE

Tilsotolimod is an investigational synthetic Toll-like receptor 9 (TLR9) agonist that has demonstrated antitumor activity in preclinical models. The ILLUMINATE-101 phase I study explored the safety, dose, efficacy, and immune effects of intratumoral (it) tilsotolimod monotherapy in multiple solid tumors.

PATIENTS AND METHODS

Patients with a diagnosis of refractory cancer not amenable to curative therapies received tilsotolimod in doses escalating from 8 to 32 mg into a single lesion at weeks 1, 2, 3, 5, 8, and 11. Additional patients with advanced malignant melanoma were enrolled into an expansion cohort at the 8 mg dose. Objectives included characterizing the safety, establishing the dose, efficacy, and immunologic assessment. Blood samples and tumor biopsies of injected and noninjected lesions were obtained at baseline and 24 hours after treatment for immune analyses.

RESULTS

Thirty-eight and 16 patients were enrolled into the dose escalation and melanoma expansion cohorts, respectively. Deep visceral injections were conducted in 91% of patients. No dose-limiting toxicities (DLT) or grade 4 treatment-related adverse events were observed. Biopsies 24 hours after treatment demonstrated an increased IFN pathway signature and dendritic cell maturation. Immunologic profiling revealed upregulation of IFN-signaling genes and modulation of genes for checkpoint proteins. In the dose escalation cohort, 12 (34%) of 35 evaluable patients achieved a best overall response rate (ORR) of stable disease (SD), whereas 3 (19%) of 16 evaluable patients in the melanoma cohort achieved stable disease.

CONCLUSIONS

Overall, tilsotolimod monotherapy was generally well tolerated and induced rapid, robust alterations in the tumor microenvironment. See related commentary by Punekar and Weber, p. 5007.

Tilsotolimod with Ipilimumab Drives Tumor Responses in Anti-PD-1 Refractory Melanoma

Many patients with advanced melanoma are resistant to immune checkpoint inhibition. In the ILLUMINATE-204 phase I/II trial, we assessed intratumoral tilsotolimod, an investigational Toll-like receptor 9 agonist, with systemic ipilimumab in patients with anti-PD-1- resistant advanced melanoma. In all patients, 48.4% experienced grade 3/4 treatment-emergent adverse events. The overall response rate at the recommended phase II dose of 8 mg was 22.4%, and an additional 49% of patients had stable disease. Responses in noninjected lesions and in patients expected to be resistant to ipilimumab monotherapy were observed. Rapid induction of a local IFNα gene signature, dendritic cell maturation and enhanced markers of antigen presentation, and T-cell clonal expansion correlated with clinical response. A phase III clinical trial with this combination (NCT03445533) is ongoing. SIGNIFICANCE: Despite recent developments in advanced melanoma therapies, most patients do not experience durable responses. Intratumoral tilsotolimod injection elicits a rapid, local type 1 IFN response and, in combination with ipilimumab, activates T cells to promote clinical activity, including in distant lesions and patients not expected to respond to ipilimumab alone.This article is highlighted in the In This Issue feature, p. 1861.

Abstract CT265: A phase 2 multicenter study to evaluate the efficacy of tilsotolimod in combination with nivolumab and ipilimumab for treatment of microsatellite-stable colorectal cancer (ILLUMINATE-206)

The checkpoint inhibitors pembrolizumab, nivolumab as monotherapy, and nivolumab in combination with ipilimumab are approved in the US for treatment of patients with previously treated microsatellite instability-high (MSI-high) or mismatch repair-deficient metastatic colorectal cancer (CRC). However, checkpoint inhibitors are not currently approved for treatment of microsatellite-stable (MSS) CRC, and patients do not appear likely to respond to these regimens. Tilsotolimod, an investigational Toll-like receptor 9 (TLR9) agonist, stimulates the innate and adaptive immune systems. In an ongoing phase 1/2 clinical study in patients with advanced melanoma who progressed on or after anti-PD-1 therapy (NCT02644967), intratumoral tilsotolimod in combination with ipilimumab was generally well-tolerated at the recommended phase 2 dose, with durable responses in some patients. Biopsies revealed localized activation of the Type-I interferon pathway, maturation of dendritic cells, and induction of MHC class I antigen presentation. Furthermore, dominant T cell clones are shared between injected and distant, non-injected lesions in responding patients.1

ILLUMINATE-206 (NCT03865082) is a phase 2 multicenter, open-label study of intratumoral tilsotolimod 8 mg in combination with ipilimumab and nivolumab at specified doses and schedules for all 3 agents. ILLUMINATE-206 will comprise multiple cohorts, including patients with immunotherapy-naïve, MSS-CRC who have received at least 2 prior regimens of therapy for advanced or metastatic disease including fluoropyrimidine-, oxaliplatin-, and irinotecan-based regimens. Eligible patients are ≥18 years with histologically-confirmed CRC, confirmed MSS status, measurable lesion(s) accessible for injection and RECIST assessment, ECOG performance status 0-1, life expectancy ≥4 months, adequate organ function, no prior TLR or immuno-oncology treatment, and no unstable CNS disease. The primary endpoint is objective response rate based on RECIST v1.1 and duration of response. Safety is a secondary endpoint, and paired blood or biopsy samples may be evaluated for tumor genetics, immune infiltrates, and gene expression. Additional patients may be enrolled in Part 1 after review of the data from the initial safety run-in of 10 patients. Based on data from Part 1, the cohort may be expanded during Part 2.

Reference Diab A, et al. Ann Oncol 2018;29(suppl_8):Abstract 1245PD.

Citation Format: Hani B. Babiker, Heinz-Josef Lenz, Aaron J. Scott, Shah Rahimian, Michael J. Overman. A phase 2 multicenter study to evaluate the efficacy of tilsotolimod in combination with nivolumab and ipilimumab for treatment of microsatellite-stable colorectal cancer (ILLUMINATE-206) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT265.

Abstract CT134: Tilsotolimod engages the TLR9 pathway to promote antigen presentation and Type-I IFN signaling in solid tumors

Background: Tilsotolimod, an investigational Toll-like receptor 9 (TLR9) agonist, modulates the tumor immune microenvironment and has single-agent antitumor activity in preclinical models. The ILLUMINATE-101 phase 1b study (NCT03052205) explored the safety, efficacy, and immune effects of intratumoral tilsotolimod in multiple solid tumors.

Methods: Adults with a histologically- or cytologically-confirmed diagnosis of cancer not amenable to curative therapies received intratumoral tilsotolimod 8, 16, 23, or 32 mg into a single lesion on Days 1, 8, and 15 of Cycle 1 and Day 1 of each subsequent 3-week cycle, for up to 17 cycles. Additionally, patients with advanced melanoma were enrolled into an expansion cohort at the recommended phase 2 dose of 8 mg. The primary objective was to characterize safety (dose escalation cohort) and efficacy (expansion cohort). Secondary objectives included pharmacokinetics of tilsotolimod. Immunological assessment of injected and non-injected tumors was an exploratory objective. Blood samples and tumor biopsies of injected lesions were obtained at baseline and 24 hours post treatment for immune analyses.

Results: A total of 54 patients were enrolled. Of the 38 patients in the dose escalation cohort, 35 had metastatic disease. Patients in this cohort had a median of 7 prior lines of treatment, and the most common cancer types were pancreatic (12 patients) and colorectal (7 patients). All 16 patients in the melanoma cohort had metastatic disease with a median of 3 lines of prior therapy, and 10 patients had elevated LDH. Injected lesions were deep and required interventional radiology in 52 of 54 patients. No dose-limiting toxicities were observed. The most common treatment-related adverse events were pyrexia, fatigue, chills, nausea, and vomiting. Compared to pretreatment, biopsies of injected tumors at 24 hours showed increased activation of the Type-I IFN pathway, upregulation of MHC class I/II, IFNγ expression, and expression of multiple immune checkpoints (i.e. PD-1, LAG3). Of the 35 evaluable patients in the dose escalation cohort, 12 (34%) achieved a best overall response of stable disease (SD). Of the 16 evaluable patients in the melanoma cohort, 3 had SD, 1 who had a 35% tumor reduction with no confirmatory scan.

Conclusions: Tilsotolimod was generally well tolerated and induced alterations in the tumor microenvironment, including immune checkpoint upregulation, activation of dendritic cells, and induction of Type-I IFN signaling. Additional clinical studies of tilsotolimod in combination with checkpoint inhibitors are underway (NCT03445533, NCT03865082, and NCT02644967).

Citation Format: Hani M. Babiker, Vivek Subbiah, Asim Ali, Alain Algazi, Jacob Schachter, Michal Lotem, Corinne Maurice-Dror, Daniel Hendler, Shah Rahimian, Hans Minderman, Cara Haymaker, Chantale Bernatchez, Ravi Murthy, Rolf Hultsch, Nadia Caplan, Gregory Woodhead, Charles Hennemeyer, Sri Chunduru, Peter Anderson, Adi Diab, Erkut Borazanci, Igor Puzanov. Tilsotolimod engages the TLR9 pathway to promote antigen presentation and Type-I IFN signaling in solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT134.

Abstract 4062: Activation of innate and adaptive immunity using intratumoral tilsotolimod (IMO-2125) as monotherapy in patients with refractory solid tumors: a phase Ib study (ILLUMINATE-101)

While checkpoint inhibitor therapy has transformed treatment of multiple tumor types, many patients remain refractory. Tilsotolimod, a toll-like receptor 9 agonist, has been shown in preclinical models to activate plasmacytoid dendritic cells and increase T cell infiltration to the tumor microenvironment. Preliminary results of a phase 1/2 study suggested that intratumoral injection of tilsotolimod in combination with ipilimumab may revive an immune response in patients with immune checkpoint inhibitor-resistant metastatic melanoma. To further explore the role of tilsotolimod in modulating the tumor immune microenvironment, we conducted a Phase Ib monotherapy trial (ILLUMINATE-101). Adults with histologically or cytologically confirmed diagnosis of cancer not amenable to curative therapies received intratumoral tilsotolimod in doses escalating from 8 mg to 32 mg into a single lesion at weeks 1, 2, 3, 5, 8, and 11. Objectives of the dose evaluation portion included characterizing safety and pharmacokinetics, and evaluating alterations in the tumor microenvironment. Blood samples and tumor biopsies of injected and distal lesions were obtained at baseline and on treatment. Immune analyses included evaluation using Nanostring and/or flow cytometry of activation of the type 1 interferon (IFN) pathway, IFN gamma levels, activation of dendritic cell subsets, and changes in T cell status. As of November 7, 2018, 41 patients have been enrolled, including 38 patients into the dose evaluation portion and 3 patients into a melanoma expansion cohort. No dose-limiting toxicities or treatment-related adverse events have been observed. Within 24 hours, fresh tumor biopsies showed significant increases in IFN gamma levels, activation of the type 1 IFN pathway, induction of an antigen processing gene signature (a measure of the MHC class I antigen presentation pathway), and maturation of dendritic cells as measured by expression of HLA-DR (MHC class II), compared to pretreatment biopsies. Of 25 evaluable patients who received at least 1 dose of tilsotolimod and had at least 1 post-baseline disease assessment, 12 (48%) had a RECIST v1.1 disease assessment of stable disease. For patients with at least one disease assessment following documentation of stable disease (n=8), duration of stable disease ranged from 0.53 to 4.2+ months, with 3 patients ongoing. These results demonstrate that single agent tilsotolimod was well tolerated and induced robust alterations in the tumor microenvironment.

Citation Format: Hani M. Babiker, Vivek Subbiah, Orla Maguire, Shah Rahimian, Hans Minderman, Cara L. Haymaker, Chantale Bernatchez, Erkut Borazanci, James Geib, Srinivas K. Chunduru, Peter M. Anderson, Igor Puzanov, Adi Diab. Activation of innate and adaptive immunity using intratumoral tilsotolimod (IMO-2125) as monotherapy in patients with refractory solid tumors: a phase Ib study (ILLUMINATE-101) [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 4062.

Starting the fight in the tumor: expert recommendations for the development of human intratumoral immunotherapy (HIT-IT)

A European Society for Medical Oncology (ESMO)-sponsored expert meeting was held in Paris on 8 March 2018 which comprised 11 experts from academia, 11 experts from the pharmaceutical industry and 2 clinicians who were representatives of ESMO. The focus of the meeting was exclusively on the intratumoral injection/delivery of immunostimulatory agents with the aim of harmonizing the standard terms and methodologies used in the reporting of human intratumoral immunotherapy (HIT-IT) clinical trials to ensure quality assurance and avoid a blurring of the data reported from different studies. The goal was to provide a reference document, endorsed by the panel members that could provide guidance to clinical investigators, pharmaceutical companies, ethics committees, independent review boards, patient advocates and the regulatory authorities and promote an increase in the number and quality of HIT-IT clinical trials in the future. Particular emphasis was placed not only on the development of precise definitions to facilitate a better understanding between investigators but also on the importance of systematic serial biopsies as a driver for translational research and the need for the recording and reporting of data, to facilitate a better understanding of the key processes involved.

Population pharmacokinetics of oral high-dose busulfan in adult patients undergoing hematopoietic stem cell transplantation

BACKGROUND AND THE PURPOSE OF THE STUDY

Many factors have been reported that contribute to the wide intra- and inter-patient variability of Busulfan (Bu) disposition. The purpose of this study was to develop a population pharmacokinetic model and to determine the covariates affecting the pharmacokinetics (PK) of Bu in Iranian adult patients who received oral high-dose as a conditioning regimen before Hematopoietic Stem Cell Transplantation (HSCT).

METHODS

A population PK analysis was performed in 30 patients who received an oral Bu and cyclophosphamide regimen before HSCT. Bu was given orally according to the protocol of the institution. In order to prevent seizures caused by Bu, phenytoin was administered orally one hour before each dose of Bu.A total of 180 blood samples were analyzed by HPLC and PK parameters were estimated by the non-linear mixed effect model by MONOLIX 3.1 program. A one-compartment model with an additive error model was used to describe the concentration-time profile of Bu.

RESULTS

Patients' disease and weight was found to be the determinant factors for clearance (CL) and the volume of distribution (Vd) according to Monolix analysis. The covariate entered in final model followed by these equations:[Formula: see text][Formula: see text] In this limited study, the age (15-43 years) had no significant effect. For a patient weighting 60 kg, the typical CL and Vd were estimated to be 13.4 l/hr and 42.6 L, respectively. The interindividual variability of CL and Vd were 13.6 and 6.3%, respectively. There was no significant metabolic induction in these four days as is evident by comparing the trough levels of Bu. However it should be mentioned that, one tailed t-test p-values of the days of two and three, two and four and three and four were 0.083, 0.069 and 0.388, respectively.

MAJOR CONCLUSIONS

Results of this study showed that the type of disease was a determinant of CL and the weight of patient was a determinant of Vd for Bu population PK parameters. A reliable PK parameters and Css, estimated from only one plasma concentrations (5 hrs after the first dose), were validated. Since these methods require few sampling and are easy to be used, the limited sampling methods might be advantageous in the routine clinical practice.