Program Information

Radio-Dynamic Therapy (RDT) for the Treatment of Late-Stage Cancers

C Ma¹*, L Chen² , R Price³ , Q Zhang⁴ , J Zeng⁵ , K Xu⁶ , Q Sun⁷ , (1) Fox Chase Cancer Center, Philadelphia, PA, (2) Fox Chase Cancer Center, Philadelphia, PA, (3) Fox Chase Cancer Center, Philadelphia, PA, (4) Wu Xi Yi Ren Tumor Hosiptal, Wuxi, Jiangsu, (5) Wuxi Yiren Cancer Hospital, Wuxi, Jiangsu, (6) Wuxi Yiren Cancer Hospital, Wuxi, Jiangsu, (7) Wuxi Yiren Cancer Hospital, Wuxi, Jiangsu

Presentations

SU-E-T-381 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: Photo-dynamic therapy (PDT) is an effective treatment modality because of the preferential absorption of photosensitizing agent in tumor cells than in surrounding normal tissues. A limitation of PDT for cancer therapy is the finite penetration of laser light to activate the targeting agent in deep-seated tumors. Radio-dynamic therapy (RDT) is designed to overcome this problem by the combination of high-energy (up to 45MV) photon beams and photo/radio-sensitizers. This work investigates the feasibility of PDT for late-stage cancer patients who are no longer respond to conventional therapies available.

Methods: The high-energy photon beams are generated using a LA45 RaceTrack Microtron (Top Grade Medical, Beijing, China). The targeting agent investigated is 5-aminolevulinic acid (5-ALA). Both in vitro cell lines and in vivo animal models have been used to investigate the mechanisms of RDT and its therapeutic effects and normal tissue toxicities. Oral 5-ALA (30-60 mg/kg) was administered 4-6 hours before the radiation treatment and the total radiation dose varied between 0.1-4.0Gy in 1-4 fractions. Clinical trials are initiated in China for late-stage cancer patients targeting both primary tumors utilizing localized therapies such as 3DCRT/IMRT and metastases using TBI.

Results: There is clear correlation between the cell death and the 5-ALA concentration/radiation dose. The therapeutic effect of RDT is demonstrated using an animal model where the volume of parotid tumors for the RT only group continued to grow after 3Gy irradiation while the RDT group showed a complete response with the same radiation dose. The preliminary clinical results showed encouraging clinical outcome.

Conclusion: RDT is a novel treatment technique that may be developed into an effective cancer treatment modality. Further studies on the mechanisms of RDT and its potential clinical applications are warranted.

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