Gadolinium Neutron Capture Therapy for Cats and Dogs with Spontaneous Tumors Using Gd-DTPA

Abstract

We conducted a clinical veterinary study on neutron capture therapy (NCT) at a neutron-producing accelerator with seven incurable pets with spontaneous tumors and gadolinium as a neutron capture agent (gadolinium neutron capture therapy, or GdNCT). Gadolinium-containing dimeglumine gadopentetate, or Gd-DTPA (Magnevist^®, 0.6 mL/kg b.w.), was used. We observed mild and reversible toxicity related to the treatment. However, no significant tumor regression in response to the treatment was observed. In most cases, there was continued tumor growth. Overall clinical improvement after treatment was only temporary. The use of Gd-DTPA for NCT had no significant effects on the life expectancy and quality of life of animals with spontaneous tumors. Further experiments using more advanced gadolinium compounds are needed to improve the effect of GdNCT so that it can become an alternative to boron neutron capture therapy. Such studies are also necessary for further NCT implementation in clinical practice as well as in veterinary medicine.

Keywords: BNCT; Gd-DTPA; GdNCT; boron neutron capture therapy; cancer; dimeglumine gadopentetate; gadolinium neutron capture therapy; large animal irradiation; spontaneous tumors; veterinary medicine.

Figure 1

Female cat “Ayuta” (11 years old) with highly differentiated adenocarcinoma in the right nasopharyngeal area, leading to worsening of nasal breathing and nasal discharge. Tumor appearance ((A), arrow) and head CT ((B), dashed circle) before irradiation, and tumor appearance ((C), arrow) and head CT ((D), dashed circle) 3 months after GdNCT. No significant changes compared to the pretreatment visualization were revealed.

Figure 2

Male dog “John” (14 years old) with chondrosarcoma in the nasal area with impaired nasal breathing and nasal discharge and tumor recurrence after repeated surgical treatment. Animal appearance before irradiation (A). Head CT after irradiation (B) with a tumor 32 × 39 × 47 mm in size (green lines, dashed red circle).

Figure 3

Male cat “Sausage” (6 years old) with squamous cell carcinoma in the left nasal area (33 × 26 × 26 mm) with bone destruction, causing impaired nasal breathing and nasal discharge, and regional lymphadenopathy. Animal positioning under the lithium target within the beam shaping assembly during neutron irradiation (A) and tumor appearance after the irradiation ((B), arrow and the circle). Two months after GdNCT, there were signs of tumor recurrence in the back of the nose, upper jaw, and corner of the eye.

Figure 4

Male cat “Lev” (11 years old) with highly differentiated squamous cell carcinoma of the oral cavity and upper jaw on the right side and metastasis to the submandibular lymph node. Animal appearance (A) and head CT (B) before irradiation with a tumor in the oral cavity 25 × 40 × 15 mm in size (green and red lines, dashed red circle). Animal positioning under the lithium target during GdNCT (C) and animal appearance after irradiation (D). Active tumor progression was found three months after irradiation.

Figure 5

Female dog “Lily” (13 years old) with a tumor of unknown origin (pathological examination was not done) in the middle lobe of the right lung with involvement of the cranial and caudal lobes and single metastases to the lungs and regional lymph nodes Animal preparation for GdNCT (A). Chest CT (B) before irradiation showed a tumor 33 × 35 × 42 mm in size (green lines, dashed red circles). Animal appearance after irradiation (C). Two months after GDNCT, chest CT scans (D) showed that the tumor mass decreased in size to 32 × 38 × 36 mm (dashed line).

Figure 6

Female cat “Marusya” (10 years old) with squamous cell carcinoma in the upper jaw on the left side with invasion into the nasal cavity and left orbital space and destruction of the upper jawbone. Animal appearance before irradiation (A) with the outer tumor mass (arrow). Head CT (B) before irradiation showed a tumor 16 × 31 mm in size (green lines, dashed red circle). Head CT after the treatment (C) showed that the tumor had increased in size to 38 × 59 mm (green and red lines, dashed red circle).

Figure 7

Male cat “Semyon” (6 years old) with osteogenic sarcoma of the right femur and iliac bone. Animal appearance before irradiation (A). CT scan before irradiation (B) showed a tumor 34 × 32 × 37 mm in size (dashed circle). Animal appearance after irradiation (C). CT scan three months after irradiation (D) revealed that the tumor had increased in size to 58 × 38 × 46 mm (arrow, dashed circle).