The Memocore™ 066 fiducial stent marker was developed by a team lead by CTO Erik Othel-Jacobsen, Pnn Medical A/S. Memocore™ 066 represents incremental innovation since the technology closely resemble the technique used in the Memokath™ product line. Memokath™ stents have been in use since the early 1990'ies and an estimated 45,000 patients have been exposed to the stents. Significant knowledge about product design and safety was therefore available already at the entry of the project.

The Memocore™ 066 is made of a biocompatible Nitinol with shape memory effect. It is inserted into the prostatic urethra and left in situ for the duration of the radiation therapy (Figure1).

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Figure 1: The Memocore™ 066 in situ in the prostatic urethra.

The proximal part of the Memocore™ 066 expands when heated to above 55-60°C (Figure 1). The properties of the Memocore™ 066 material make it "super soft" when the stent is cooled below 7°C. This feature is used when the Memocore™ 066 is removed after completed radiotherapy treatment, simply by flushing with cold water while removing the stent.

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Figure 2: The Memocore™ 066 stent after expansion.

An optimal fiducial marker is key
The trend in radiotherapy is to use higher and higher doses within external beam radiation therapy (EBRT). Therefore, precision is important. Further, it has been shown that the prostate moves more than originally expected. It moves centimeters - even within seconds (Figure 3). The movement of the prostate is e.g. influenced by the bowel movements of rectum (1). These factors make a well-functioning fiducial marker important.

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Figure 3: The prostate can move centimeters within few seconds depending upon e.g. rectal filling - here visualized with the Memocore™ stent in situ. This makes real-time tracking of the prostate position important.

The concept of Memocore™ 066 was tested pre-clinically, technically and clinically in close cooperation with Aalborg University Hospital where Chief Physicist Jesper Carl and Dr. Mats Holmberg were prime-movers. A total of 128 patients were treated during the development. The clinical results showed that the stent has a low migration rate (1.6%) and a side-effect profile which is similar to the picture seen in radiotherapy with no stent present. It was concluded that Memocore™066 has a favorable benefit/risk profile and a CE-mark was issued during autumn 2009. The Memocore™ 066 is now available for routine use.

In conclusion, the Memocore™ 066 meets an unmet need for a visible, high precision 3D marker that can be used in connection with EBRT. It is associated with little risk of migration and it features easy, operator-independent insertion and removal. The Memocore™ 066 is, in other words, a reversible fiducial marker. The concept is innovative and unique since the Memocore™ 066 is the only true 3D marker which can be used for EBRT for treatment of cancer.

Memocore™ will create value for both hospitals and patients

Value for Patients - Better Outcomes: It is Pnn Medical's hope to be able to document that use of the Memocore™ 066 increases the curative effect of radiation and at the same time reduces the number of side effects due to higher precision and higher dosing of the radiation beam. The cancer cells are hit by the beam whilst the amount of normal tissue exposed to radiation is limited. Overall, it is the expectation that use of the Memocore™ 066 to result in a higher life expectancy and reduced morbidity. Long-term data are necessary to prove this.

The Memocore™ 066's visibility on high volt images also provides better radiotherapy on old equipment. This will improve the treatment effect/side-effect ratio for patients treated with old equipment.

Value for Hospitals - Increased Productivity: The Memocore™ 066 will offer a more efficient treatment. This will reduce treatment time and thereby allow more treatments per accelerator per day - a significant bottle neck in today's cancer treatment. As prostate cancer requires several treatments (currently >35 per patient) it takes up much of the accelerator capacity in the western world. The increased precision in the radiation beam further opens up for increase in the radiation dose will reduce the number of necessary treatments per patient.

Future treatment areas
Future potential implications of the Memocore™ are not only improved survival of prostate patients. The technique may in the future open up for improved treatment modalities of other cancers such as lung- pancreas-, and uterine-cancer.  

Reference list:
(1)   Fiorino C, Foppiano F, Franzone P, Broggi S, Castellone P, Marcenaro M, et al. Rectal and bladder motion during conformal radiotherapy after radical prostatectomy. Radiother Oncol 2005 Feb;74(2):187-95.