Intratumoral Delivery of Plasmid IL12 Via Electroporation Leads to Regression of Injected and Noninjected Tumors in Merkel Cell Carcinoma - PubMed (original) (raw)

. 2020 Feb 1;26(3):598-607.

doi: 10.1158/1078-0432.CCR-19-0972. Epub 2019 Oct 3.

Natalie V Longino 3, Natalie J Miller 3, Rima Kulikauskas 3, Jayasri G Iyer 3, Dafina Ibrani 3, Astrid Blom 3, David R Byrd 4, Upendra Parvathaneni 5, Christopher G Twitty 6, Jean S Campbell 2 6, Mai H Le 6, Sharron Gargosky 6, Robert H Pierce 2 6, Richard Heller 7, Adil I Daud 8, Paul Nghiem 2 3

Affiliations

Intratumoral Delivery of Plasmid IL12 Via Electroporation Leads to Regression of Injected and Noninjected Tumors in Merkel Cell Carcinoma

Shailender Bhatia et al. Clin Cancer Res. 2020.

Abstract

Purpose: IL12 promotes adaptive type I immunity and has demonstrated antitumor efficacy, but systemic administration leads to severe adverse events (AE), including death. This pilot trial investigated safety, efficacy, and immunologic activity of intratumoral delivery of IL12 plasmid DNA (tavo) via in vivo electroporation (i.t.-tavo-EP) in patients with Merkel cell carcinoma (MCC), an aggressive virus-associated skin cancer.

Patients and methods: Fifteen patients with MCC with superficial injectable tumor(s) received i.t.-tavo-EP on days 1, 5, and 8 of each cycle. Patients with locoregional MCC (cohort A, N = 3) received one cycle before definitive surgery in week 4. Patients with metastatic MCC (cohort B, N = 12) received up to four cycles total, administered at least 6 weeks apart. Serial tumor and blood samples were collected.

Results: All patients successfully completed at least one cycle with transient, mild (grades 1 and 2) AEs and without significant systemic toxicity. Sustained (day 22) intratumoral expression of IL12 protein was observed along with local inflammation and increased tumor-specific CD8+ T-cell infiltration, which led to systemic immunologic and clinical responses. The overall response rate was 25% (3/12) in cohort B, with 2 patients experiencing durable clinical benefit (16 and 55+ months, respectively). Two cohort A patients (1 with pathologic complete remission) were recurrence-free at 44+ and 75+ months, respectively.

Conclusions: I.t.-tavo-EP was safe and feasible without systemic toxicity. Sustained local expression of IL12 protein and local inflammation led to systemic immune responses and clinically meaningful benefit in some patients. Gene electrotransfer, specifically i.t.-tavo-EP, warrants further investigation for immunotherapy of cancer.

©2019 American Association for Cancer Research.

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Figures

Figure 1.

Figure 1.

Increased IL12 gene and protein expression posttherapy in electroporated lesions. A, IL12 gene expression (IL12A subunit) was elevated in several tumors posttreatment compared with pretreatment. Changes in gene expression were analyzed using NanoString nCounter platform. B, Paired pre- and post-biopsy samples from 10 patients were evaluable for IL12 p70 protein levels by MAGPIX. Data are presented as fold change (post-/pretreatment). The majority (6 of 10; 60%) had greater than 2-fold increase in IL12 protein levels suggesting sustained expression (at day 22) after treatment on days 1, 5, and 8. no., number.

Figure 2.

Figure 2.

I.t.-tavo-EP induces intratumoral infiltration and systemic MCPyV-specific T-cell expansion. MCPyV-specific CD8 T cells were evaluated intratumorally (A) and in PBMCs (B), using MCPyV-specific tetramers. A, Paired pre- and post-fresh tumor biopsies were cultured in the presence of IL2 and IL15 to obtain TILs. B, Systemic evaluation of MCPyV-specific CD8 T cells from PBMCs was performed as in A. Fold changes, post-IL12 versus pre-IL12 therapy, in the MCPyV-specific tetramer-positive population, as described in Materials and Methods, are shown (the dotted line indicates a 2-fold change). Responders (R) are in green; nonresponders (NR) are in red. Tetramer HLA type is denoted on the _x_-axis, and stars denote samples that were negative for tetramer positive cells at both pre- and post-time points. no., number.

Figure 3.

Figure 3.

Regression of treated and untreated lesions is associated with robust T-cell responses and infiltration. A, Schema of treatment and response in Pt#2 with baseline (red circles), regressed lesions (green circles), a persistent lesion (yellow circle). Lesions treated with i.t.-tavo-EP are shown as lightning bolts (blue: current cycle; white: prior cycles). Two untreated lesions that regressed are shown in top right panel (blue arrows). B, Tetramer staining of MCPyV-specific CD8 T cells from TIL from pre- and posttherapy from Pt#2. Tetramer-positive CD8 T cells are circled in each panel. Negative control is an HLA mismatched donor. C, T-cell receptor (TCR) beta chain sequencing was used to determine TCR variable beta chain diversity using ImmunoSeq V3 (Adaptive Biotechnology) from pre- and posttreatment tumor specimens (patient number is shown on _x_-axis, and * denotes patients in whom the pre- and posttreatment samples were from different lesions). Data are presented as fold change (a ratio of the difference between the posttreatment T-cell fraction and pretreatment T-cell fraction over the pretreatment T-cell fraction). Bars are colored in correlation with clinical response: responder (R, green) and nonresponder (NR, red). The dotted line denotes a greater than or equal to 2-fold change. D and E, Multispectral IHC images of pretreatment show an MCC tumor (CK20, white/light blue) with very few infiltrating T cells (CD8 in green and CD4 in red; D). Three weeks after treatment (E), there was a large infiltrate of CD8 T cells (green), accompanied by increased PD-1 (magenta) and PD-L1 (orange) and loss of tumor (CK20, white/light blue). C1, cycle 1; C2, cycle 2; no., number; RT, radiotherapy; Tx, treatment.

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