ADV: Positive results in porous silicon liver cancer trial
David White
ASX/MEDIA RELEASE 15th February 2005
Positive Phase IIa Trial Results in Liver Cancer
BrachySil(TM) trial confirms safety and tumor regression in further patients
Global nanotechnology company pSivida Limited (NASDAQ:PSDV, ASX:PSD,
Xetra:PSI) is pleased to announce that its trial in inoperable primary liver
cancer patients continues to show excellent results. Data from the second
patient cohort of the current Phase IIa trial has further demonstrated that
BrachySil(TM) (32-P BioSilicon(TM)) is safe and effective in tumor
regression with increased efficacy.
Results of the second group of 4 patients, 12 weeks after their
BrachySil(TM) treatment, revealed an average tumor regression by volume of
80% as determined by CT scanning. In some smaller tumors 100% regression was
observed, a level of performance not seen with other intratumoral
approaches. The study also demonstrated that there were no product-related
adverse effects. Patients will continue to be monitored for 6 months post
treatment.
These excellent results follow the announcement in October 2004 of the
interim results from the first 4 patients, which also showed no
product-related adverse effects and reported up to 60% regression of tumors.
BrachySil(TM) is a micron-sized particle in which the isotope 32-phosphorus
is immobilized. PSivida believes that this product is unique in that it
demonstrates a very high degree of isotope retention, thus reducing the risk
of soluble radioactive material affecting healthy hepatic tissue or entering
the circulation and causing systemic toxicity.
pSivida's Managing Director, Mr. Gavin Rezos, said, "This further human
evaluation of BioSilicon(TM) has met our expectations in terms of safety and
the performance of the fine gauge needle injection procedure. We are also
very pleased with the significant level of tumor regression achieved given
the low dose being administered. Proof of the ability of BrachySil(TM) to
retain radioactivity at the injection site is another significant outcome of
the trial."
Other treatments for primary liver cancer include a variety of embolisation
and radiofrequency ablation techniques. pSivida believes that BrachySil(TM)
potentially offers the interventional radiologist a more versatile and safer
product for the treatment of such tumors. The procedure is undertaken
without surgery under local anesthetic and patients can be discharged the
following day.
pSivida currently plans to pursue a 'device-based' regulatory approval route
for BrachySil(TM) which could result in a much shorter development and
registration timeframe than that commonly associated with a drug-based
approval.
Following the completion of analysis of the final Phase IIa trial results
pSivida expects to begin a dose profiling study during 2005. pSivida then
intends to commence multi-centre pivotal registration trials during 2005
involving patients in Asia, Europe and the US. The objective of these trials
is to obtain data to support registration of BrachySil(TM) as an approved
treatment for primary liver cancer.
pSivida plans to expand the use of BrachySil(TM) as a treatment for a wider
range of solid tumor indications. A Phase IIa clinical trial is scheduled to
commence for a second cancer indication within the next year.
The brachytherapy market is currently over US$600 million per annum and is
expected to exceed US$1 billion within the next few years (Bio-Tech
Systems). BrachySil(TM) has the potential to significantly expand the
current market size through its application to other cancers The study has
established four key findings:
SAFETY - No product related adverse events
Unlike other liver brachytherapy approaches that involve delivery via the
hepatic artery and, in some cases, result in radioactivity affecting healthy
tissue, BrachySil(TM) is administered directly into tumors restricting
radioactivity to the tumor itself.
EFFICACY - Treated tumors demonstrate significant tumor regression
Implantation of tumors with BrachySil(TM) has resulted in tumoricidal
activity around the implantation site. Although the primary objective of the
study was to determine the safety profile of BrachySil(TM), CT scan analysis
of tumors at the time of treatment and 3 months later demonstrates
significant tumor regression in targeted lesions with a maximum regression
of 100% from the dose used in the trial.
SPECIFICITY- Retention of radioactivity in the tumor
A key finding is that the radioactive 32P-BioSilicon(TM)M nanostructured
microparticles remain in the tumor with no or insignificant detectable
radioactive leakage.
EASE OF APPLICATION - Practical and rapid treatment of tumors with
ultrasound and CT guidance The procedure has been shown to be
straightforward and accurate for the treatment of tumors. From a market
perspective this demonstration is in line with the company's strategy to
develop a simple procedure for the interventional radiologist to selectively
treat specific tumors. A multi injector is in design phase to treat larger
tumors with multiple implantations from a single entry.
NOTES ON BRACHYSIL AND COMPETITIVE ADVANTAGES IN BRACHYTHERAPY
1. BrachySil(TM) is being manufactured to worldwide regulatory guidelines by
supply chain contract partners including HighForce, Micron Group, Atomising
Systems and AEA Technology QSA subsidiary Auriga Medical, a leading global
producer and supplier of radioisotopes for healthcare.
2. Brachytherapy treatment utilising BioSilicon(TM)M includes the following
significant potential advantages:
Short range - 32-P isotope has a short active range resulting in less
damage to healthy tissue.
Immobilization - 32-P device is immobilized in the tumor, significantly
reducing risk of leakage or systemic side effects.
Ease of application - BrachySil(TM) is delivered under local anesthetic
and patients can be discharged the next day.
Direct delivery - BrachySil(TM) is delivered via fine gauge needle,
minimizing side effects and tissue trauma without the need for shielded
rooms or robotic injectors allowing treatment in hospitals without the need
for investment in specialised facilities.
Range of tumors - fine gauge needle delivery allows potential application
to many solid tumors, unlike current brachytherapy products.
Distribution - 32-P half-life of 14 days allows more convenient
distribution to hospitals and application in the patient.
Manufacture - BioSilicon(TM) is radiation hard allowing ease of
manufacture of BrachySil(TM) from phosphorous-doped silicon used in the
electronics industry without the need to build costly manufacturing
facilities.
-ENDS