to current chemotherapy schedules. Histotripsy is an entirely new paradigm of treatment that will become widely available to interventional oncologists in the coming years and has the potential to revolutionize how we deliver cancer care.


References


1. Xu Z, Ludomirsky A, Eun LY, Hall TL, Tran BC, Fowlkes JB, et al. Controlled ultrasound tissue erosion. IEEE Trans Ultrason Ferroelectr Freq Control. 2004;51(6):726–36.


2. Xu Z, Owens G, Gordon D, Cain C, Ludomirsky A. Noninvasive creation of an atrial septal defect by histotripsy in a canine model. Circulation. 2010;121(6):742–9.


3. Xu Z, Hall TL, Vlaisavljevich E, Lee FT, Jr. Histotripsy: The first noninvasive, non- ionizing, non-thermal ablation technique based on ultrasound. Int J Hyperthermia. 2021;38(1):561–75.


4. Schuster TG, Wei JT, Hendlin K, Jahnke R, Roberts WW. Histotripsy Treatment of benign prostatic enlargement using the Vortx Rx system: Initial Human safety and efficacy outcomes. Urology. 2018;114:184–7.


5. Smolock AR, Cristescu MM, Vlaisavljevich E, Gendron-Fitzpatrick A, Green C, Cannata J, et al. Robotically assisted sonic therapy as a noninvasive nonthermal ablation modality: Proof of concept in a porcine liver model. Radiology. 2018:171544.


adverse event (8 days of urinary retention). There was an improvement in prostate-related symptoms and quality of life. Interestingly there was no visible reduction in prostate size or improvement of postvoid residuals, which was attributed to the transperineal approach blocking energy delivery.4


In the THERESA study, the


successful creation of an ablation zone encompassing the tumor was achieved in all patients at a median time of 25 minutes with no device-related adverse events. Two of the eight patients (one with HCC and one with colorectal metastases) in this study had off-target (abscopal) effects on nontreated tumors with continued decrease in tumor markers and stable or decreasing non- treated tumors over the 2-month study follow-up period.3


Currently, there are


two actively recruiting multicenter trials for the treatment of liver tumors in both the United States and Europe.


14 IRQ | FALL 2021


The future of histotripsy At baseline, histotripsy will be an alternative to current thermal ablation modalities in ultrasound- accessible locations given the non- invasive nature and precision of the treatment. Histotripsy may also open the possibility for noninvasive and safe ablation in critical locations that are difficult or not possible to treat with current technologies, such as adjacent to bile ducts and vessels in the central liver given the collagen- sparing properties. A more aspirational role would be for histotripsy to be an adjunct to conventional systemic cancer treatments. For example, when considering the possibility of combining histotripsy tumor treatments with immunotherapy to treat metastasis, we can imagine a future where a patient has a routine outpatient histotripsy procedure as an immune-stimulating treatment either once or at routine intervals similar


6. Longo KC, Knott EA, Watson RF, Swietlik JF, Vlaisavljevich E, Smolock AR, et al. Robotically assisted sonic therapy (RAST) for noninvasive hepatic ablation in a porcine model: Mitigation of Body wall damage with a modified pulse sequence. Cardiovasc Intervent Radiol. 2019;42(7):1016–23.


7. Longo KC, Zlevor AM, Laeseke PF, Swietlik JF, Knott EA, Rodgers AC, et al. Histotripsy ablations in a porcine liver model: Feasibility of respiratory motion compensation by alteration of the ablation zone prescription shape. Cardiovasc Intervent Radiol. 2020;43(11):1695–701.


8. Knott EA, Swietlik JF, Longo KC, Watson RF, Green CM, Abel EJ, et al. Robotically-assisted sonic therapy for renal ablation in a live porcine model: Initial preclinical results. J Vasc Interv Radiol. 2019;30(8):1293–302.


9. Swietlik JF, Mauch SC, Knott EA, Zlevor A, Longo KC, Zhang X, et al. Noninvasive thyroid histotripsy treatment: Proof of concept study in a porcine model. Int J Hyperthermia. 2021;38(1):798–804.


10. Worlikar T, Mendiratta-Lala M, Vlaisavljevich E, Hubbard R, Shi J, Hall TL, et al. Effects of histotripsy on local tumor progression in an in vivo orthotopic rodent liver tumor model. BME Frontiers. 2020.


11. Qu S, Worlikar T, Felsted AE, Ganguly A, Beems MV, Hubbard R, et al. Non-thermal histotripsy tumor ablation promotes abscopal immune responses that enhance cancer immunotherapy. J Immunother Cancer. 2020;8(1).


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