A phase II study of siG12D-LODER in combination with chemotherapy in patients with locally advanced pancreatic cancer (PROTACT)

TPS4672

Background: KRAS alterations are the most frequent driver alterations identified in pancreas cancer; however, KRAS has remained an elusive therapeutic target. siG12D-LODER is a novel, miniature bio-degradable polymeric matrix encompassing a novel small interfering RNA targeting KRAS G12D and all additional G12X mutations (G12C, G12V...). The siG12D-LODER is inserted directly into the pancreas tumor via endoscopic intervention. A Phase 1/2a dose escalation and expansion study of patients receiving a one-time dose of siG12D-LODER with ongoing chemotherapy demonstrated that the combination was well-tolerated and safe and exhibited promising potential efficacy with 10/12 patients achieving disease control and median overall survival 15.1 months (Golan, Oncotarget 2015). Methods: This phase 2 study was initially designed as a randomized, two arm, open label study of gemcitabine and nab-paclitaxel with or without siG12D-LODER for patients with locally advanced pancreas cancer with planned 40 patients in each arm and primary endpoint of progression-free survival. Eighteen patients were enrolled in the chemotherapy alone arm and 18 in the chemotherapy and siG12D-LODER arm. After an interim analysis, the study design has been amended and is now a single arm study in which patients (N=39) with both borderline resectable and locally advanced pancreas cancer will receive investigator’s choice of chemotherapy (the combination of gemcitabine/nab-paclitaxel or modified FOLFIRINOX) and all patients will receive up to three doses of the siG12D-LODER administered once every 12 weeks. Primary endpoint is overall response rate after final siG12D-LODER insertion. Secondary endpoints include duration of response, progression-free survival, overall survival, time to response, percentage of patients proceeding to surgical resection, and percentage of patients receiving radiation therapy. Exploratory analyses include evaluation of KRAS mutation status and monitoring of circulating free DNA and circulating tumor cells. The amended protocol is now open for accrual and four patients having been enrolled to date. Trial accrual is anticipated to be completed by December 2020. Clinical trial information: NCT01676259 .

Ammonium and arsenic trioxide are potent facilitators of oligonucleotide function when delivered by gymnosis

Oligonucleotide (ON) concentrations employed for therapeutic applications vary widely, but in general are high enough to raise significant concerns for off target effects and cellular toxicity. However, lowering ON concentrations reduces the chances of a therapeutic response, since typically relatively small amounts of ON are taken up by targeted cells in tissue culture. It is therefore imperative to identify new strategies to improve the concentration dependence of ON function. In this work, we have identified ammonium ion (NH4+) as a non-toxic potent enhancer of ON activity in the nucleus and cytoplasm following delivery by gymnosis. NH4+ is a metabolite that has been extensively employed as diuretic, expectorant, for the treatment of renal calculi and in a variety of other diseases. Enhancement of function can be found in attached and suspension cells, including in difficult-to-transfect Jurkat T and CEM T cells. We have also demonstrated that NH4+ can synergistically interact with arsenic trioxide (arsenite) to further promote ON function without producing any apparent increased cellular toxicity. These small, inexpensive, widely distributed molecules could be useful not only in laboratory experiments but potentially in therapeutic ON-based combinatorial strategy for clinical applications.

Preclinical Safety Evaluation in Rats of a Polymeric Matrix Containing an siRNA Drug Used as a Local and Prolonged Delivery System for Pancreatic Cancer Therapy

Conventional chemotherapy treatments for pancreatic cancer are mainly palliative. RNA interference (RNAi)-based drugs present the potential for a new targeted treatment. LOcal Drug EluteR (LODER(TM)) is a novel biodegradable polymeric matrix that shields drugs against enzymatic degradation and releases small interfering RNA (siRNA) against G12D-mutated KRAS (siG12D). siG12D-LODER has successfully passed a phase 1/2a clinical trial. Such a formulation necessitates biocompatibility and safety studies. We describe the safety and toxicity studies with siG12D-LODER in 192 Hsd:Sprague Dawley rats, after repeated subcutaneous administrations (days 1, 14, and 28). Animals were sacrificed on days 29 and 42 (recovery phase). In all groups, no adverse effects were noted, and all animals showed favorable local and systemic tolerability. Histopathologically, LODER implantation resulted in the expected capsule formation, composed of a thin fibrotic tissue. On the interface between the cavity and the capsule, a single layer composed of macrophages and multinucleated giant cells was observed. No difference was noted between the placebo and siG12D-LODER groups. These findings provide valuable information for future preclinical studies with siRNA-bearing biodegradable polymers and for the safety aspects of RNAi-based drugs as a targeted therapy.

Multistep, effective drug distribution within solid tumors

The distribution of drugs within solid tumors presents a long-standing barrier for efficient cancer therapies. Tumors are highly resistant to diffusion, and the lack of blood and lymphatic flows suppresses convection. Prolonged, continuous intratumoral drug delivery from a miniature drug source offers an alternative to both systemic delivery and intratumoral injection. Presented here is a model of drug distribution from such a source, in a multistep process. At delivery onset the drug mainly affects the closest surroundings. Such 'priming' enables drug penetration to successive cell layers. Tumor 'void volume' (volume not occupied by cells) increases, facilitating lymphatic perfusion. The drug is then transported by hydraulic convection downstream along interstitial fluid pressure (IFP) gradients, away from the tumor core. After a week tumor cell death occurs throughout the entire tumor and IFP gradients are flattened. Then, the drug is transported mainly by 'mixing', powered by physiological bulk body movements. Steady state is achieved and the drug covers the entire tumor over several months. Supporting measurements are provided from the LODER system, releasing siRNA against mutated KRAS over months in pancreatic cancer in-vivo models. LODER was also successfully employed in a recent Phase 1/2 clinical trial with pancreatic cancer patients.

Novel Kras-directed therapy in combination with chemotherapy for locally advanced pancreatic adenocarcinoma

270

Background: K-Ras mutation G12D is most prevalent in pancreatic adenocarcinoma (PDAC). siRNA against the K-RasG12D(siG12D) mutant had showed significant preclinical anti-tumor effects. siG12D LODER - is a miniature biodegradable polymeric matrix that encompasses anti K-RasG12D siRNA drug, designed to release the drug regionally along 4 months. The siG12D LODER is placed with Endoscopic US biopsy. Methods: Open label phase I study of patients with locally advanced non-operable PDAC in the first-line setting. Patients were assigned to receive siG12D LODERs in a dose escalation, dose cohorts were: 0.025mg, 0.75mg and 3.0mg. Gemcitabine 1000 mg/m2IV was given on a weekly basis, following the siG12D LODER insertion, until disease progression. The RP2D (recommended phase II dose) was further examined in highest dose cohort in combination with modified Folfirinox (Oxaliplatin 85mg/m2, Irinotecan 150mg/m2 followed by a Fluorouracil continuous IV infusion 2,400mg/m2 46 hours every 2 weeks). Follow up period was 8 weeks and survival follow up until death. Primary study objectives were to determine the dose-limiting toxicities (DLT) and maximum tolerated doses (MTD). Results: 15 patients with locally advanced PDAC have been enrolled. Two patients were omitted from study but followed for safety due to metastatic disease detected on day 1 post siG12D LODER implant imaging. Median age = 70 (range 52-85); male:female =8:7. Among 13 treated patients, the most frequent adverse events observed in the study were typically grade 1- 2 in severity; 4 patients experienced serious adverse events (SAE). No DLTs were observed. CT performed 8-12 weeks following the procedure showed tumor regression in 66% (8 of the first 12 patients, 7/8 from 2nd and 3rd cohorts).Reduction in tumor marker CA 19-9 was observed in 64% (7/11) of patients. Median overall survival was 16.26 months, 14.01 months and 15.11 months in the 0.025 mg, 0.75 mg and the 3 mg treatment groups respectively. Conclusions: The combination of siG12D LODER and chemotherapy is well tolerated. The combination has demonstrated promising efficacy in locally advanced pancreatic cancer with durable responses. NCT01188785. Clinical trial information: NCT01188785.

A phase I trial of a local delivery of siRNA against k-ras in combination with chemotherapy for locally advanced pancreatic adenocarcinoma

4037

Background:K-Ras mutation G12D is most prevalent in pancreatic adenocarcinoma (PDAC). siRNA against the K-RasG12D(siG12D) mutant had showed significant preclinical anti-tumor effects. siG12D LODER - miniature biodegradable polymeric matrix that encompasses anti-K-RasG12D siRNA drug, is placed with Endoscopic US biopsy and designed to continuously release the drug regionally over a period of 4 months. Methods: Open label phase I study of patients with locally advanced non-operable PDAC in the first-line setting. Patients were assigned to receive siG12D LODERs in dose escalation cohorts: 0.025mg, 0.75mg and 3.0mg. Gemcitabine 1000 mg/m2IV was given weekly, following siG12D LODER insertion. The RP2D (recommended phase II dose) was further examined in 3.0 mg dose cohort in combination with modified Folfirinox (Oxaliplatin 85mg/m2, Irinotecan 150mg/m2, Fluorouracil infusion 2,400mg/m2 46 hours, every 2 weeks). Follow up period was 8 weeks and survival follow up until death. Primary study objectives were to determine the dose-limiting toxicities (DLT) and maximum tolerated doses (MTD). Results:15 patients have been enrolled. 2 patients were omitted from study due to metastatic disease detected on day 1 post siG12D LODER implant imaging . Median age = 70 (range 52-85); male:female 8:7. Among 13 treated patients, the most frequent adverse events observed in the study were typically grade 1- 2 in severity; 4 patients experienced serious adverse events (SAE), one procedure related. No DLTs were observed. MTD was not reached. CT performed 8-10 weeks following the procedure showed stable disease in all patients. Reduction in tumor marker CA 19-9 was observed in 64% (7/11) of patients. The median survival of 13 patients was 16 months ( 8/13 patients still alive at analysis). Conclusions: The combination of siG12D LODER and chemotherapy is well tolerated. The combination has demonstrated promising efficacy in locally advanced PDAC with durable responses. Phamocodynamic endpoints are currently being examined in an expansion cohort in operable patients. A phase II randomized trial is planned in order to investigate efficacy of siG12D LODER in locally advanced non-operable PDAC. Clinical trial information: NCT01188785.