Another NanoKnife pilot study

We reported several months ago on a pilot study of focal irreversible electroporation (IRE or NanoKnife®) in Sydney and London. Murray et al. have now published the early results of a pilot test at Memorial Sloan-Kettering Cancer Center.

A chart review of 25 patients treated with partial gland IRE ablation revealed the following complications after a median follow-up of 10.9 months:

  • 14/25 patients (56 percent) incurred transient and mild to moderate (grade 2 or less) urinary symptoms, including blood in urine and urinary tract infection.
  • 2/25 patients (8 percent) had severe (grade 3) complications requiring intervention: epididymitis and urinary tract infection.
  • Among those with good baseline urinary function, 94 percent were back to baseline function at 12 months; two patients required pads.
  • At 12 months, 1 previously potent patient had new erectile dysfunction.

There was a routine follow-up biopsy 6 months after treatment. At that time, 4/25 patients (16 percent) were found to have residual cancer in the ablation treatment zone. In the previously reported pilot study, 6/24 patients (25 percent) had residual disease after a first treatment. It is surprising that residual disease was found within the treatment zone here, indicating incomplete ablation. These levels of local recurrence are about the same as has been reported with other kinds of focal thermal ablation (e.g., HIFU, cryotherapy, and laser ablation).

IRE requires full anesthesia with complete paralysis, so if there is no advantage in terms of toxicity or cancer control, one of the other forms of ablation that require only local anesthesia may be a better choice for some. Still, these are only small pilot studies, and continued trials may perfect the technique and get better results.

Editorial note: This commentary was written for The “New” Prostate Cancer InfoLink by Allen Edel.

7 Responses

  1. I had a NanoKnife operation done at Offenbach, Germany. Apparently they have done about 300 of these operations already.

    After my operation I was told to keep the catheter in for 2 weeks and I should expect blood in my urine (hematuria) for some time. Both are considered in the study presented here as side effects while I think these are normal outcomes of the operation that you have to expect.

    Keeping the catheter for more than 3 days were 86% of the grade 2 side effects in the study while blood in the urine were 67% of the grade 1 side effects. Without these, the transient and mild side effects (grade 2 and below) were only 12% and not 54% as reported.

    I got my whole prostate ablated, so this was not focal treatment. A PSMA PET/MRI done a few months after the operation showed no cancer in the treated area.

    At Offenbach, before they plan a focal NanoKnife treatment, they do an mpMRI plus a transperineal 3D-biopsy to exactly locate the cancer. I think the 25% failure rate reported in the presented study results from trying to locate the cancer in the prostate with MRI only. The Offenbach clinic reports better results:

    — “during the follow-up period of up to 4 years, the recurrence rates were 0/55 (Gleason less than 7), 3/117 (Gleason 7) and 10/67 (Gleason greater than 7)”

  2. Georg:

    This commentary reports on partial gland ablation only. In this small study, 16% had recurrences in the treatment zone, which obviously cannot be ascribed to a lack of MRI-targeted detection. In this study, NanoKnife did not provide complete ablation of the cancer in some patients. I’m not at all certain that a PSMA PET is the best tool for gauging recurrence within the prostate. PSMA is known to be found on the surface of metastatic prostate cancer, but it’s ability to detect cancer within the prostate of a favorable-risk patient has not been documented. I know that there are several ongoing clinical trials looking at its use in intermediate- or high-risk patients. Given this uncertainty, you might want to have a follow-up biopsy and not rely solely on a PSMA PET scan.

  3. Allan,

    I did a PSMA PET/CT before the operation and the cancer in the prostate was displayed fine and was obvious. If it does not show up any more after the operation I am confident that it is gone — just as my Cyberknife doctor which I saw regarding treatment of my metastases. Also, since I did no focal treatment my prostate is destroyed and fully ablated now, you cannot make a biopsy any more.

    You write: “obviously cannot be ascribed to a lack of MRI-targeted detection“. If you do a focal treatment the cancer will appear again in the untreated area of the prostate gland. If the MRI did not show any cancer in that area before the treatment it will not be selected for treatment with NanoKnife.

    When I read your posts, you always point out that there are lesions that are too small to be detected with MRI. These can be detected with a biopsy, however. So if you leave an area untreated because the MRI did not show any lesions in there, there can be lesions in that area that are then detected with a following biopsy.


  4. You keep ignoring what I wrote: cancer was found in the TREATED region. Consider the possibility that PSMA appears on the prostate cancer cell surface only in cells that have mutated to a certain degree. Possibly you had some in your prostate like that. Possibly you had more that did not display the antigen. PET PSMA has never been validated for use within the prostate – only for extraprostatic cancer. They are different animals. Even a saturation biopsy may miss some cancer.

    I congratulate you for volunteering for the experiment. But to be safe with an unproven therapy, you have to continue to monitor it very closely. Ablation is apparently not as complete as you think it is.

  5. In the presented study they apparently did not differentiate whether the biopsy cores were taken from a treated or a non-treated area. They write: “Any patient subsequently treated for prostate cancer progression within the zone of ablation or on the contralateral prostate lobe was reported as treatment failure“. And following that regarding the four patients reported as treatment failure: “Three men received subsequent definitive surgical treatment, 1 for Gleason 3 + 4 of ipsilateral lobe and 2 for Gleason 3 + 4 in the contralateral lobe“.

    So two of the failures were definitely outside the treated area.

    A very similar, however, prospective study by Willemien van den Bos concludes: “IRE in prostate cancer results in a completely ablated, sharply demarcated ablation areas without leaving any viable cell within the electrode configuration.“

    Willemien told me in an email: “As written in our publications, no residual tumorous cells were found within the ablated area”.

    Therefore I question the results of this study.


  6. “Of 25 patients, 4 (16%) had cancer in the zone of ablation on routine follow-up biopsy at 6 months.”

    This is a highly experimental treatment you volunteered for, and very little is known with any degree of certainty. The authors are very careful researchers at perhaps the most prestigious cancer center in the world (Memorial Sloan-Kettering Cancer Center) published in the peer-reviewed, official journal of the American Urological Association.

    It is called “confirmation bias” when someone only believes what confirms one’s preconceptions and ignores what one doesn’t want to believe is true. This can be harmful to one’s health. I again caution you to have a follow-up biopsy.

  7. Dear Georg:

    Please note that we have just fixed the error in your original comment above. This just came to my attention. I am not sure why it was not showing up as it was originally typed.

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