An Intraprostatic Modified Release Formulation of Antiandrogen 2-Hydroxyflutamide for Localized Prostate Cancer

Tissue distribution of ethanol after intraprostatic injection using a porous needle

Purpose

To develop a safe and precise method for intraprostatic injection, and to establish correlation between the volume of ethanol injectate and the volume of subsequent infiltrated prostate tissue.

Materials and methods

We performed intraprostatic injection of 96% ethanol using a needle which has a segment of its wall made of capillary membrane with hundreds of pores in an acute and chronic canine experiment, in heart-beating cadaveric organ donors, and in a xenograft model of human prostate cancer. Whole mount tissue sections were used for three-dimensional reconstruction of the necrotic lesions and calculation of their volumes.

Results

The ethanol injection resulted in oval shaped lesions of well-delineated coagulative necrosis. In both healthy human and canine prostates, the prostatic pseudocapsule and neurovascular bundle remained intact without evidence of disruption. There was a linear correlation between administered volume of ethanol and the volume of necrotic lesion. Regression analysis showed strong correlation in the acute canine experiments and in experiments performed on xenografts of human prostate cancer. A formula was calculated for each experiment to estimate the relationship between the injected volume and the volume of infiltrated prostate tissue area.

Conclusions

Intraprostatic injection using a porous needle allows for effective and predictable tissue distribution of the injectate in the prostate. Through varying the volume of the agent injected and use of needles with a different length of the porous segment, the volume of infiltrated tissue could be adjusted allowing for targeted focal treatment.

Biodistribution of fluorescence-labelled EGF protein from slow release NanoZolid depots in mouse

AIM

The study was designed to evaluate the ability of the calcium sulfate based NanoZolid® drug delivery technology to locally release the epidermal growth factor (EGF) protein while maintaining its biological activity.

METHODS

NanoZolid-formulated EGF protein labelled with a near infrared dye (EGF-NIR) depots or EGF-NIR dissolved in PBS were injected subcutaneously into mice bearing EGF receptor (EGFR) positive human A549 lung cancer tumors inoculated subcutaneously. The release and biodistribution of the EGF-NIR were investigated in vivo longitudinally up to 96 h post administration, utilizing whole body fluorescence imaging. In order to confirm the in vivo findings, histological analysis of tumor cryosections was performed to investigate EGF-NIR fluorescent signal and EGFR expression level by immunofluorescence labelling.

RESULTS

The in vivo fluorescence imaging showed a controlled release profile of the EGF-NIR loaded in the NanoZolid depots compared to free EGF-NIR. Histological analysis of the tumors further demonstrated a prevailing distribution of EGF-NIR in regions with high levels of EGFR expression.

CONCLUSION

Calcium sulfate based depots can be used to formulate EGF while maintaining its biological activity, e.g. receptor binding capability. This may have a good clinical potential for local delivery of biomolecules to enhance treatment efficacy and minimize systemic adverse effects.

Liproca Depot: A New Antiandrogen Treatment for Active Surveillance Patients

BACKGROUND

There is increasing interest in nonmorbid treatments for low- and intermediate-risk prostate cancer with fewer side effects than surgery or radiotherapy.

OBJECTIVE

To investigate the tolerability, safety, and antitumor effects of the intraprostatic NanoZolid depot formulation Liproca Depot (LIDDS AB, Uppsala, Sweden) with antiandrogen 2-hydroxyflutamide (2-HOF) in men with low- or intermediate-risk localized prostate cancer managed with active surveillance.

DESIGN, SETTING, AND PARTICIPANTS

This clinical phase 2b trial, LPC-004, involved 61 patients. The 2-HOF-containing formulation Liproca Depot was injected transrectally into the prostate under ultrasound guidance. A single dose of 35% or 45% of the prostate volume (study part 1) and a fixed dose of 16 or 20 ml (study part 2) of the formulation were evaluated.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSES

The primary endpoints were tolerability and the reduction in serum prostate-specific antigen (PSA) 5 mo after injection. Antitumor effects were evaluated with magnetic resonance imaging (MRI) and prostate biopsies. Quality of life was assessed using a validated questionnaire (International Prostate Symptom Score).

RESULTS AND LIMITATIONS

All doses were safe and well tolerated, without hormonal side effects. In part 2 of the study, the PSA reduction was greatest for the group receiving 16 ml, with an average decrease of 14%, and 95% of patients had a PSA reduction. Some 78% of patients showed a prostate volume decrease compared to baseline. Prostate MRI and biopsies confirmed stable or reduced lesion size. However, post treatment biopsies were performed at the discretion of the investigator, and not routinely. Most patients were amenable to a second injection.

CONCLUSIONS

PSA and prostate volume decreased in most patients. Indications of efficacy were shown by post-treatment MRI and biopsies demonstrating stabilization or regression in the majority of cases.

PATIENT SUMMARY

Liproca Depot is a safe, minimally invasive treatment that offers the potential for cancer control in patients with intermediate-risk prostate cancer. Further clinical evaluation is warranted.

Loco-regional drug delivery in oncology: current clinical applications and future translational opportunities

Introduction: Drug-based treatment regimens for cancer are often associated with off-target toxic side effects and low penetration of the drug at the tumor site leading to patient morbidity and limited efficacy. Loco-regional drug delivery has the potential to increase efficacy while concomitantly reducing toxicity.Areas covered: Clinical applications using loco-regional delivery include intra-arterial drug delivery in retinoblastoma, direct intra-tumoral (IT) injection of ethanol for ablation in hepatocellular carcinoma (HCC) and the use of HIPEC in peritoneal carcinomas. In recent years, there has been a significant increase in both approved products and clinical trials, with a particular emphasis on drug delivery platforms such as drug-eluting beads for HCC and hydrogel platforms for intravesical delivery in bladder cancer.Expert opinion: Development of loco-regional drug-delivery systems has been slow, limited by weak clinical data for early applications and challenges relating to dosing, delivery and retention of drugs at the site of action. However, there is increasing focus on the potential of loco-regional drug delivery when combined with bespoke drug-delivery platforms. With the growth in immunotherapies, the use of IT delivery to drive priming of the anti-tumor response has opened up a new field of opportunity for loco-regional drug delivery.

Toll-Like Receptor 9 Agonists in Cancer

Toll-like receptor 9 (TLR9) is a pattern recognition receptor that is predominantly located intracellularly in immune cells, including dendritic cells, macrophages, natural killer cells, and other antigen-presenting cells (APC). The primary ligands for TLR9 receptors are unmethylated cytidine phosphate guanosine (CpG) oligodinucleotides (ODN). TLR9 agonists induce inflammatory processes that result in the enhanced uptake and killing of microorganisms and cancer cells as well as the generation of adaptive immune responses. Preclinical studies of TLR9 agonists suggested efficacy both as monotherapy and in combination with several agents, which led to clinical trials in patients with advanced cancer. In these studies, intravenous, intratumoral, and subcutaneous routes of administration have been tested; with anti-tumor responses in both treated and untreated metastatic sites. TLR9 agonist monotherapy is safe, although efficacy is minimal in advanced cancer patients; conversely, combinations appear to be more promising. Several ongoing phase I and II clinical trials are evaluating TLR9 agonists in combination with a variety of agents including chemotherapy, radiotherapy, targeted therapy, and immunotherapy agents. In this review article, we describe the distribution, structure and signaling of TLR9; discuss the results of preclinical studies of TLR9 agonists; and review ongoing clinical trials of TLR9 agonists singly and in combination in patients with advanced solid tumors.

A polymeric paste-drug formulation for intratumoral treatment of prostate cancer

OBJECTIVE

Focal therapy has emerged as a treatment option for low- to intermediate-risk localized prostate cancer (PCa) patients, to balance the risks for urinary and sexual morbidity of radical treatment with the psychological burden of active surveillance. In this context, we developed ST-4PC, an injectable, polymeric paste formulation containing docetaxel (dtx) and bicalutamide (bic) for image-guided focal therapy of PCa. The objective of this work was to evaluate the in vitro characteristics and in vivo toxicity and efficacy of ST-4PC.

MATERIAL AND METHODS

In vitro drug release was evaluated using high-performance liquid chromatography. In vivo toxicity of blank- and drug-loaded ST-4PC was assessed in mice and rats. Tumor growth inhibition was evaluated in LNCaP subcutaneous (s.c.) and LNCaP-luc orthotopic xenograft models. Using the s.c. model, mice were monitored weekly for weight loss, tumor volume (TV) and serum PSA. For the orthotopic model, mice were additionally monitored for bioluminescence as measure of tumor growth.

RESULTS

ST-4PC demonstrated a sustained and steady release of incorporated drugs with 50% dtx and 20% bic being released after 14 days. While no systemic toxicity was observed, dose-dependent local side effects from dtx developed in the s.c. but not in the orthotopic model, illustrating the limitations of s.c. models for evaluating local cytotoxic therapy. In the s.c. model, 0.1%/4% and 0.25%/4% dtx/bic ST-4PC paste significantly reduced PSA progression, but did not have a significant inhibitory effect on TV. ST-4PC loaded with 1%/4% dtx/bic significantly reduced TV, serum PSA, and bioluminescence in the orthotopic xenograft model. Compared with drugs dissolved in DMSO, ST-4PC significantly delayed tumor growth.

CONCLUSION

Image-guided focal therapy using ST-4PC demonstrated promising inhibition of PSA progression and orthotopic tumor growth in vivo without significant toxicity, and warrants further clinical evaluation.