Prophylactic In Vivo Hematopoietic Stem Cell Gene Therapy with an Immune Checkpoint Inhibitor Reverses Tumor Growth in Syngeneic Mouse Tumor Models

Abstract

Population-wide testing for cancer-associated mutations has established that more than one-fifth of ovarian and breast carcinomas are associated with inherited risk. Salpingooophorectomy and/or mastectomy are currently the only effective options offered to women with high-risk germline mutations. Our goal here is to develop a long-lasting approach that provides immunoprophylaxis for mutation carriers. Our approach leverages the fact that at early stages, tumors recruit hematopoietic stem/progenitor cells (HSPC) from the bone marrow and differentiate them into tumor-supporting cells. We developed a technically simple technology to genetically modify HSPCs in vivo. The technology involves HSPC mobilization and intravenous injection of an integrating HDAd5/35þþ vector. In vivo HSPC transduction with a GFP-expressing vector and subsequent implantation of syngeneic tumor cells showed >80% GFP marking in tumor-infiltrating leukocytes. To control expression of transgenes, we developed a miRNA regulation system that is activated only when HSPCs are recruited to and differentiated by the tumor. We tested our approach using the immune checkpoint inhibitor anti-PD-L1-g1 as an effector gene. In in vivo HSPC-transduced mice with implanted mouse mammary carcinoma (MMC) tumors, after initial tumor growth, tumors regressed and did not recur. Conventional treatment with an anti-PD-L1 mAb had no significant antitumor effect, indicating that early, self-activating expression of anti-PD-L1-g1 can overcome the immunosuppressive environment in MMC tumors. The efficacy and safety of this approach was further validated in an ovarian cancer model with typical germline mutations (ID8 p53 À/À brca2 À/À ), both in a prophylactic and therapeutic setting. This HSPC gene therapy approach has potential for clinical translation.Significance: Considering the limited prophylactic options that are currently offered to women with high-risk germ-line mutations, the in vivo HSPC gene therapy approach is a promising strategy that addresses a major medical problem.

Curative in vivo hematopoietic stem cell gene therapy of murine thalassemia using large regulatory elements

“…These are critical obstacles to a widespread application for ex vivo HSPC gene therapy of hemoglobinopathies, particularly in older patients and patients with comorbidities. We have demonstrated the safety and efficacy of this approach in several murine disease models ( 8 – 10 ) and, recently, in nonhuman primates ( 11 ). In both species, we have addressed a major problem associated with intravenous HDAd5/35++ injection, namely acute innate immune responses, by a prophylaxis regimen that blocked proinflammatory cytokines.…”

“…Targeted integration can be achieved via homology-dependent DNA repair (7). We have recently shown that our approach results in an amelioration of murine thalassemia intermedia (8), the correction of murine hemophilia (9), and the reversion of spontaneous cancer (10). First data in nonhuman primates…”

“…Targeted integration can be achieved via homology-dependent DNA repair ( 7 ). We have recently shown that our approach results in an amelioration of murine thalassemia intermedia ( 8 ), the correction of murine hemophilia ( 9 ), and the reversion of spontaneous cancer ( 10 ). First data in nonhuman primates show that the in vivo HSPC gene therapy approach is safe when combined with glucocorticoid, IL-6, and IL-1β receptor antagonist pretreatment to suppress innate immune responses after intravenous HDAd5/35++ injection ( 11 ).…”

The Ovarian Transcriptome of Reproductively Aged Multiparous Mice: Candidate Genes for Ovarian Cancer Protection

“…Mouse models have been used to study OC risk factors, including obesity [15], inflammation [16], age [8], and genetic inheritance [17], among others. Continuing the recent work on peritoneal tumor spread and systemic inflammation in an aged syngeneic female C57BL/6 mouse model of OC maintained in multiparous and nulliparous regimens [18], here, we studied the effect of parity history on the ovarian transcriptome in intact, uninduced animals.…”

Understanding and addressing barriers to successful adenovirus-based virotherapy for ovarian cancer

“…Furthermore, the combination with TIGIT blockade, an inhibitory NK receptor associated with T cell exhaustion phenotypes [177], increased NK cytotoxicity. Considering that current prevention methods are limited for high-risk women with germline mutations, Li et al developed a method to genetically modify hematopoietic stem/progenitor cells (HSPC) in vivo based on an integrating Ad5/35 + + vector expressing α-PD-L1-γ1 under the control of a miRNA regulation system that is activated only when HSPCs are recruited to and differentiated by the tumor into tumor-supporting cells [178]. They stablished a feasible in situ transduction strategy and demonstrated that intratumoral expression of α-PD-L1-γ1 early during tumor development successfully reduced primary tumor growth and prevention of recurrence.…”