Enabling Chemo-Immunotherapy with HIFU in Canine Cancer Patients

High intensity focused ultrasound (HIFU) is a promising non-invasive technique for treating solid tumors using thermal and histotripsy-based mechanical ablation. However, its clinical significance in different tumor types is not fully understood. To assess its therapeutic efficacy and immunomodulatory properties, we compared HIFU thermal ablation and histotripsy ablation in dogs with spontaneous tumors. We also evaluated the ability of non-ablative HIFU-based mild hyperthermia (40-45 ºC) to improve Doxorubicin delivery and immunomodulation. Our results showed that HIFU thermal ablation induced tumor remission in the majority of treated patients over 60 days, while histotripsy achieved partial response to stable disease persistence. The adverse effects of thermal ablation were minor to moderate, while histotripsy exposures were relatively well-tolerated. Furthermore, we observed a correlation between HIFU-therapeutic response and serum anti-tumor cytokine profiles and the presence of functionally active cytotoxic immune cells in patients. Similarly, Doxorubicin-treated patients showed improved drug delivery, efficacy, and anti-tumor immune responses with HIFU hyperthermia. In conclusion, our study demonstrates that depending on the tumor type and treatment parameters, HIFU treatments can enable tumor growth control, immune activation, and chemotherapy in veterinary patient. These findings have significant clinical implications and highlight the potential of HIFU as a promising cancer treatment approach.

Risk factors for intraoperative hemorrhage and perioperative complications and short- and long-term outcomes during surgical patent ductus arteriosus ligation in 417 dogs

OBJECTIVE

To evaluate the short- and long-term outcomes of dogs undergoing surgical ligation for a left-to-right shunting patent ductus arteriosus (PDA), identify risk factors for intraoperative hemorrhage and intra- and postoperative complications, and report overall mortality rates.

ANIMALS

417 client-owned dogs undergoing surgical ligation for a left-to-right shunting PDA between January 2010 and January 2020.

PROCEDURES

Data recorded included patient signalment, echocardiogram findings, intraoperative complications and mortality, postoperative complications, and short- and long-term outcomes.

RESULTS

There was no association between age and risk of intraoperative hemorrhage (P = .7), weight and intraoperative hemorrhage (P = .96), or increasing left atrium-to-aortic (LA:Ao) ratio and intraoperative hemorrhage (P = .08). Intraoperative hemorrhage occurred in 10.8% of patients. Intraoperative mortality was 2%. Ninety-five percent of dogs experiencing intraoperative hemorrhage survived to discharge. Survival to discharge was 97%. One- and 5-year survival rates were 96.4% and 87%, respectively.

CLINICAL RELEVANCE

Surgical ligation for a left-to-right shunting PDA is recommended due to the good long-term prognosis. Certain preoperative factors such as age, weight, and the presence and degree of mitral valve regurgitation had no detectable association with risks of intraoperative hemorrhage and, therefore, should not preclude surgical treatment for a left-to-right shunting PDA. Future studies are needed to further assess the association between increasing LA:Ao ratio and risk of intraoperative hemorrhage.

Effect of Bidirectional Insertion of External Skeletal Fixation Pins on Axial Pullout Strength in Canine Cadaveric Bone

OBJECTIVE

 The aim of this study was to evaluate the effect of bidirectional insertion on axial pullout strength of tapered run out (TRO), traditional negative profile (TNP) and positive profile (PP) pins.

STUDY DESIGN

 Cadaveric adult canine tibiae were harvested. Tapered run out pins (Group 1) were inserted unidirectionally to the desired position; bidirectionally past the desired position, then withdrawn to the desired position (Group 2); and bidirectionally as described for Group 2, repeated twice (Group 3). Traditional negative profile pins (Group 4-6) and PP pins (Group 9-11) were placed in the same manner. Tapered run out (Group 7), TNP (Group 8) and PP pins (Group 12) were driven unidirectionally such that the shaft of the pin violated the cis-cortex. A servohydraulic testing machine extracted the pins and measured axial peak pullout strength.

RESULTS

 Positive profile pins had significantly greater pullout strength than TRO and TNP pins placed unidirectionally to the desired position. Method of insertion had no effect on peak pullout strength of TNP pins. TRO and PP pins inserted unidirectionally to the desired position had significantly greater peak pullout strengths than insertion bidirectionally or if the shaft of the pin violated the cis-cortex.

CONCLUSION

 The authors recommend that pins used for external skeletal fixation should be placed unidirectionally to the desired position with fluoroscopic guidance, intra-operative depth gauge measurements or measurements from preoperative radiographs. Repositioning pins results in loss of peak pullout strength with TRO and PP pins.

Transcutaneous transmission of photobiomodulation light to the spinal canal of dog as measured from cadaver dogs using a multi-channel intra-spinal probe

The target level photobiomodulation (PBM) irradiances along the thoracic to lumbar segment of the interior spinal canal in six cadaver dogs resulting from surface illumination at 980 nm were measured. Following a lateral hemi-laminectomy, a flexible probe fabricated on a plastic tubular substrate of 6.325 mm diameter incorporating nine miniature photodetectors was embedded in the thoracic to lumbar segment of the spinal canal. Intra-spinal irradiances at the nine photodetector sites, spanning an approximate 8 cm length caudal to T13, were measured for various applied powers of continuous wave (CW) surface illumination at 980 nm with a maximal power of 10 W corresponding to a surface irradiance of 3.14 W/cm². The surface illumination conditions differed in skin transmission when the probe was off-contact with tissue and probe-skin contact when the skin was in place. For each condition of surface illumination, the beam was directed to respectively T13 (surface site 1), a spinal column site 4 cm caudal to T13 (surface site 5), and a spinal column site 8 cm caudal to T13 (surface site 9). Off-contact surface irradiation of 3.14 W/cm² at surface sites 1, 5, and 9 transmitted respectively 234.0 ± 120.7 μW/cm², 230.7 ± 178.3 μW/cm², and 130.2 ± 169.6 μW/cm² to the spinal canal without the skin, and respectively 35.7 ± 33.2 μW/cm², 50.9 ± 75.3 μW/cm², and 15.7 ± 16.3 μW/cm² with the skin. Transmission with skin was as low as 12% of the transmission without the skin. On-contact surface irradiation of 3.14 W/cm² at surface sites 1, 5, and 9 transmitted respectively 44.6 ± 43.1 μW/cm², 85.4 ± 139.1 μW/cm², and 22.0 ± 23.6 μW/cm² to the spinal canal. On-contact application increased transmission by a maximum of 67% comparing to off-contact application. The information gathered highlights the need to clinically consider the impact of skin transmission and on-contact application technique when attempting to treat spinal cord disease with PBM.

High Intensity Focused Ultrasound (HIFU) Heating Improves Perfusion and Antimicrobial Efficacy in Mouse Staphylococcus Abscess

Chronic wounds typically require long-duration treatment with a combination of antibiotics administered systemically. This incurs adverse side effects and can require aversive surgical treatments and limb amputations. To improve non-invasive antimicrobial therapy, the objective of this study was to investigate antimicrobial chemotherapy combined with high-intensity focused ultrasound (HIFU) heating (HT). A Staphylococcus aureus abscess (80 ± 30 mm³) was generated in the mouse flank region. Once the average temperature (~42 °C-46 °C) in the abscess was reached with HIFU-HT, a broad-spectrum antimicrobial (ciprofloxacin, 10 mg/kg) and perfusion marker (Evans blue dye, 40 mg/kg wt) were administered intravenously via the tail vein. Four hours later, mean abscess perfusion and colony-forming units (CFUs) per gram of abscess were determined. HIFU-HT increased abscess perfusion by ~2.5-fold (4 ± 0.6 µg/mL Evans blue) compared with control (1.5 ± 0.7 µg/mL), and improved antimicrobial efficacy to decrease percentage average survival of S. aureus by ~20% (46 ± 7 CFUs/g of abscess) versus that seen with ciprofloxacin alone (61 ± 4 CFU/g). Our in vivo data suggest that HIFU-HT can improve antimicrobial treatment responses against deep-seated bacteria in abscess wounds via enhanced perfusion.

Flexible nine-channel photodetector probe facilitated intraspinal multisite transcutaneous photobiomodulation therapy dosimetry in cadaver dogs

Noninvasive photobiomodulation therapy (PBMT) of spinal cord disease remains speculative due to the lack of evidence for whether photobiomodulatory irradiances can be transcutaneously delivered to the spinal cord under a clinically acceptable PBMT surface irradiation protocol. We developed a flexible nine-channel photodetection probe for deployment within the spinal canal of a cadaver dog after hemilaminectomy to measure transcutaneously transmitted PBMT irradiance at nine sites over an eight-cm spinal canal length. The probe was built upon a 6.325-mm tubular stem, to the surface of which nine photodiodes were epoxied at approximately 1 cm apart. The photodiode has a form factor of 4.80  mm×2.10  mm×1.15  mm (length×width×height). Each photodiode was individually calibrated to deliver 1 V per 7.58  μW/cm2 continuous irradiance at 850 nm. The outputs of eight photodiodes were logged concurrently using a data acquisition module interfacing eight channels of differential analog signals, while the output of the ninth photodiode was measured by a precision multimeter. This flexible probe rendered simultaneous intraspinal (nine-site) measurements of transcutaneous PBMT irradiations at 980 nm in a pilot cadaver dog model. At a surface continuous irradiance of 3.14  W/cm2 applied off-contact between L1 and L2, intraspinal irradiances picked up by nine photodiodes had a maximum of 327.48  μW/cm2 without the skin and 5.68  μW/cm2 with the skin.

Agreement of Axillary and Auricular Temperature with Rectal Temperature in Systemically Healthy Dogs Undergoing Surgery

Obtaining a patient's temperature is an important part of a patient's physical examination. As human medicine transitions to noninvasive temperature measurements, so does veterinary medicine. Historically, temperature measurement has been obtained from rectal readings; however, alternative methods, such as axillary and auricular temperatures, are increasing in popularity. The purpose of the study was to compare these alternative techniques to the gold standard of rectal temperature. Temperatures were obtained three ways for each patient: rectal, axillary, and auricular. Results indicated a positive linear relationship between rectal and axillary temperatures (bivariate correlation coefficient [r] = 0.65, P < .001) and axillary and auricular temperatures (r = 0.55, P < .001). Agreement was strongest between rectal and auricular temperatures (r = 0.80, P < .001). The average discrepancy between axillary and rectal temperature was 1.2°C [2.1°F] with the highest difference being 4.0°C [7.3°F]. The average discrepancy between auricular and rectal temperature was 0.6°C [1.2°F] with the highest difference being 2.2°C [4.1°F]. Despite auricular temperatures having stronger agreement, Bland-Altman Limits of Agreement testing revealed that it was a poor predictor of rectal temperature. Based on these results, axillary and auricular temperatures should not be substituted for rectal temperature.

Hypo-fractionated Radiation, Magnetic Nanoparticle Hyperthermia and a Viral Immunotherapy Treatment of Spontaneous Canine Cancer

It has recently been shown that cancer treatments such as radiation and hyperthermia, which have conventionally been viewed to have modest immune based anti-cancer effects, may, if used appropriately stimulate a significant and potentially effective local and systemic anti-cancer immune effect (abscopal effect) and improved prognosis. Using eight spontaneous canine cancers (2 oral melanoma, 3 oral amelioblastomas and 1 carcinomas), we have shown that hypofractionated radiation (6 x 6 Gy) and/or magnetic nanoparticle hyperthermia (2 X 43°C / 45 minutes) and/or an immunogenic virus-like nanoparticle (VLP, 2 x 200 μg) are capable of delivering a highly effective cancer treatment that includes an immunogenic component. Two tumors received all three therapeutic modalities, one tumor received radiation and hyperthermia, two tumors received radiation and VLP, and three tumors received only mNP hyperthermia. The treatment regimen is conducted over a 14-day period. All patients tolerated the treatments without complication and have had local and distant tumor responses that significantly exceed responses observed following conventional therapy (surgery and/or radiation). The results suggest that both hypofractionated radiation and hyperthermia have effective immune responses that are enhanced by the intratumoral VLP treatment. Molecular data from these tumors suggest Heat Shock Protein (HSP) 70/90, calreticulin and CD47 are targets that can be exploited to enhance the local and systemic (abscopal effect) immune potential of radiation and hyperthermia cancer treatment.