Toll-Like Receptor 4 Agonist Injection With Concurrent Radiotherapy in Patients With Metastatic Soft Tissue Sarcoma: A Phase 1 Nonrandomized Controlled Trial

Abstract

Importance: Metastatic soft tissue sarcomas (STSs) have limited systemic therapy options, and immunomodulation has not yet meaningfully improved outcomes. Intratumoral (IT) injection of the toll-like receptor 4 (TLR4) agonist glycopyranosyl lipid A in stable-emulsion formulation (GLA-SE) has been studied as immunotherapy in other contexts.

Objective: To evaluate the safety, efficacy, and immunomodulatory effects of IT GLA-SE with concurrent radiotherapy in patients with metastatic STS with injectable lesions.

Design, setting, and participants: This phase 1 nonrandomized controlled trial of patients with STS was performed at a single academic sarcoma specialty center from November 17, 2014, to March 16, 2016. Data analysis was performed from August 2016 to September 2022.

Interventions: Two doses of IT GLA-SE (5 μg and 10 μg for 8 weekly doses) were tested for safety in combination with concurrent radiotherapy of the injected lesion.

Main outcomes and measures: Primary end points were safety and tolerability. Secondary and exploratory end points included local response rates as well as measurement of antitumor immunity with immunohistochemistry and T-cell receptor (TCR) sequencing of tumor-infiltrating and circulating lymphocytes.

Results: Twelve patients (median [range] age, 65 [34-78] years; 8 [67%] female) were treated across the 2 dose cohorts. Intratumoral GLA-SE was well tolerated, with only 1 patient (8%) experiencing a grade 2 adverse event. All patients achieved local control of the injected lesion after 8 doses, with 1 patient having complete regression (mean regression, -25%; range, -100% to 4%). In patients with durable local response, there were detectable increases in tumor-infiltrating lymphocytes. In 1 patient (target lesion -39% at 259 days of follow-up), TCR sequencing revealed expansion of preexisting and de novo clonotypes, with convergence of numerous rearrangements coding for the same binding sequence (suggestive of clonal convergence to antitumor targets). Single-cell sequencing identified these same expanded TCR clones in peripheral blood after treatment; these T cells had markedly enhanced Tbet expression, suggesting TH1 phenotype.

Conclusions and relevance: In this nonrandomized controlled trial, IT GLA-SE with concurrent radiotherapy was well tolerated and provided more durable local control than radiotherapy alone. Patients with durable local response demonstrated enhanced IT T-cell clonal expansion, with matched expansion of these clonotypes in the circulation. Additional studies evaluating synergism of IT GLA-SE and radiotherapy with systemic immune modulation are warranted.

Trial registration: ClinicalTrials.gov Identifier: NCT02180698.

Figure 1.. Local Response of Lesions Receiving Intratumoral Glycopyranosyl Lipid A in Stable-Emulsion Formulation

A, Spider plot demonstrating change from baseline of tumor size and its durability beyond the trial period. B, Best percent change (which was at the end of follow-up time point for all patients) by cohort and histologic subtype.

Figure 2.. Local Control After Intratumoral Glycopyranosyl Lipid A in Stable-Emulsion Formulation (IT GLA-SE) Compared With Concomitant Lesions

A, Percent change in size of lesions at end of same follow-up period for tumors receiving IT GLA-SE plus radiotherapy (orange) vs tumors receiving radiation only (blue) or no local treatment (green). B, Representative computed tomograms of lesions at baseline and at last follow-up in a patient with undifferentiated round cell sarcoma and complete regression of tumor after IT GLA-SE and patient with leiomyosarcoma −79% in size after IT GLA-SE.

Figure 3.. Local Immune Infiltration After Intratumoral Glycopyranosyl Lipid A in Stable-Emulsion Formulation (IT GLA-SE) in Durable Responders

A, Multiplex immunohistochemical analysis found a detectable increase in CD4 and CD8 T-cell infiltration after treatment with IT GLA-SE. One patient had a detectable increase in CD4 T-cell infiltration from 11% to 34% of all cells counted, in addition to an increase in CD8 infiltration from 0.3% to 3.4%. Another patient had a detectable increase in CD8 T cells (3% to 22% of all cells counted) with a relative decrease in the proportion of T-regulatory cells (scale bars = 100 μm). B, Top clonotypes after IT GLA-SE. Tumor-infiltrating lymphocytes (TILs) were present in 1 patient, with red denoting clonotypes also present in pretreatment TILs. Inset boxes indicate breakdown of specific T-cell receptor (TCR) β DNA sequences coding for same variable amino acid region (red denotes dominant sequence). C, Matched single-cell TCR α and TCR β sequences and their gene expression heat map from posttreatment peripheral blood mononuclear cells. Green and yellow columns on left denote clonotypes expanded in posttreatment TILs. Color bar denotes standardized z score.