Development of a liver-specific tet-on inducible system for AAV vectors and its application in the treatment of liver cancer

Recombinant adeno-associated virus (rAAV) are effective gene delivery vehicles that can mediate long-lasting transgene expression. However, tight regulation and tissue-specific transgene expression is required for certain therapeutic applications. For regulatable expression from the liver we designed a hepatospecific bidirectional and autoregulatory tetracycline (Tet)-On system (Tet bidirAlb) flanked by AAV inverted terminal repeats (ITRs). We characterized the inducible hepatospecific system in comparison with an inducible ubiquitous expression system (Tet bidirCMV) using luciferase (luc). Although the ubiquitous system led to luc expression throughout the mouse, luc expression derived from the hepatospecific system was restricted to the liver. Interestingly, the induction rate of the Tet bidir Alb was significantly higher than that of Tet bidirCMV, whereas leakage of Tet bidir Alb was significantly lower. To evaluate the therapeutic potential of this vector, an AAV-Tet bidir-Alb-expressing interleukin-12 (IL-12) was tested in a murine model for hepatic colorectal metastasis. The vector induced dose-dependent levels of IL-12 and interferon-γ (IFN-γ), showing no significant toxicity. AAV-Tet bidir-Alb-IL-12 was highly efficient in preventing establishment of metastasis in the liver and induced an efficient T-cell memory response to tumor cells. Thus, we have demonstrated persistent, and inducible in vivo expression of a gene from a liver-specific Tet-On inducible construct delivered via an AAV vector and proved to be an efficient tool for treating liver cancer. © The American Society of Gene & Cell Therapy.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Association of Combination of Conformation-Specific KIT Inhibitors With Clinical Benefit inPatients WithRefractory Gastrointestinal Stromal Tumors A Phase 1b/2a Nonrandomized Clinical Trial

IMPORTANCE Many cancer subtypes, including KIT-mutant gastrointestinal stromal tumors (GISTs), are driven by activating mutations in tyrosine kinases and may initially respond to kinase inhibitors but frequently relapse owing to outgrowth of heterogeneous subclones with resistance mutations. KIT inhibitors commonly used to treat GIST (eg, imatinib and sunitinib) are inactive-state (type II) inhibitors. OBJECTIVE To assess whether combining a type II KIT inhibitor with a conformationcomplementary, active-state (type I) KIT inhibitor is associated with broad mutation coverage and global disease control. DESIGN, SETTING, AND PARTICIPANTS A highly selective type I inhibitor of KIT, PLX9486, was tested in a 2-part phase 1b/2a trial. Part 1 (dose escalation) evaluated PLX9486 monotherapy in patients with solid tumors. Part 2e (extension) evaluated PLX9486-sunitinib combination in patients with GIST. Patients were enrolled from March 2015 through February 2019; data analysis was performed from May 2020 through July 2020. INTERVENTIONS Participants received 250, 350, 500, and 1000mg of PLX9486 alone (part 1) or 500 and 1000mg of PLX9486 together with 25 or 37.5mg of sunitinib (part 2e) continuously in 28-day dosing cycles until disease progression, treatment discontinuation, or withdrawal. MAIN OUTCOMES AND MEASURES Pharmacokinetics, safety, and tumor responseswere assessed. Clinical efficacy end points (progression-free survival and clinical benefit rate) were supplemented with longitudinal monitoring of KIT mutations in circulating tumor DNA. RESULTS A total of 39 PLX9486-naive patients (median age, 57 years [range, 39-79 years]; 22 men [56.4%]; 35 [89.7%] with refractory GIST) were enrolled in the dose escalation and extension parts. The recommended phase 2 dose of PLX9486 was 1000mg daily. At this dose, PLX9486 could be safely combined with 25 or 37.5mg daily of sunitinib continuously. Patients with GIST who received PLX9486 at a dose of 500mg or less, at the recommended phase 2 dose, and with sunitinib had median (95% CI) progression-free survivals of 1.74 (1.54-1.84), 5.75 (0.99-11.0), and 12.1 (1.34-NA) months and clinical benefit rates (95% CI) of 14%(0%-58%), 50% (21%-79%), and 80% (52%-96%), respectively. CONCLUSIONS AND RELEVANCE In this phase 1b/2a nonrandomized clinical trial, type I and type II KIT inhibitors PLX9486 and sunitinib were safely coadministered at the recommended dose of both single agents in patients with refractory GIST. Results suggest that cotargeting 2 complementary conformational states of the same kinase was associated with clinical benefit with an acceptable safety profile