Olivier Chapet

Heat Shock Protein 27 as a New Therapeutic Target for Radiation Sensitization of Head and Neck Squamous Cell Carcinoma

In a wide range of human cancers, increased levels of heat shock protein 27 (Hsp27) are closely associated with tumorigenesis, metastasis, resistance to anticancer therapeutics, and thus poor prognosis. In this study, we evaluate the radiosensitizing effects of Hsp27 gene silencing using OGX-427, a second-generation antisense oligonucleotide (ASO), on the radioresistant head and neck squamous cell carcinoma (HNSCC) SQ20B cells. In vitro, the downregulation of Hsp27 significantly enhanced radiation-induced apoptotic and clonogenic death, and promoted Akt inactivation. In vivo, combining OGX-427 with local tumor irradiation (5 x 2 Gy) led to a significant regression of SQ20B tumors related to a high rate of apoptosis and decreased levels of glutathione antioxidant defenses. Increasing the total radiation dose (15 x 2 Gy) significantly amplified the radiosensitizing effect of OGX-427. Treatment of tumors with OGX-427 plus radiation resulted in a decrease in angiogenesis associated with a reduced activation of the Akt pathway. Furthermore, the combined treatment enhanced the survival of SQ20B-bearing mice and showed no signs of acute and delayed toxicity. Our findings demonstrate for the first time that Hsp27 knockdown enhances the cytotoxic effects of radiotherapy in vivo and provide preclinical proof of principle for clinical trials using Hsp27 antisense technology in the treatment of patients with HNSCC radioresistant cancers.

Prostate Hypofractionated Radiation Therapy With Injection of Hyaluronic Acid: Acute Toxicities in a Phase 2 Study

PURPOSE Hypofractionated radiation therapy (RT) in prostate cancer can be developed only if the risk of rectal toxicity is controlled. In a multicenter phase 2 trial, hypofractionated irradiation was combined with an injection of hyaluronic acid (HA) to preserve the rectal wall. Tolerance of the injection and acute toxicity rates are reported. METHODS AND MATERIALS The study was designed to assess late grade 2 toxicity rates. The results described here correspond to the secondary objectives. Acute toxicity was defined as occurring during RT or within 3 months after RT and graded according to the Common Terminology Criteria for Adverse Events version 4.0. HA tolerance was evaluated with a visual analog scale during the injection and 30 minutes after injection and then by use of the Common Terminology Criteria at each visit. RESULTS From 2010 to 2012, 36 patients with low-risk to intermediate-risk prostate cancer were included. The HA injection induced a mean pain score of 4.6/10 ± 2.3. Thirty minutes after the injection, 2 patients still reported pain (2/10 and 3/10), which persisted after the intervention. Thirty-three patients experienced at least 1 acute genitourinary toxicity and 20 patients at least 1 acute gastrointestinal toxicity. Grade 2 toxicities were reported for 19 patients with urinary obstruction, frequency, or both and for 1 patient with proctitis. No grade 3 or 4 toxicities were reported. At the 3-month visit, 4 patients described grade 2 obstruction or frequency, and no patients had any grade 2 gastrointestinal toxicities. CONCLUSIONS The injection of HA makes it possible to deliver hypofractionated irradiation over 4 weeks with a dose per fraction of > 3 Gy, with limited acute rectal toxicity.

Accuracy of Elastic Fusion of Prostate Magnetic Resonance and Transrectal Ultrasound Images under Routine Conditions: A Prospective Multi-Operator Study

Purpose To evaluate in unselected patients imaged under routine conditions the co-registration accuracy of elastic fusion between magnetic resonance (MR) and ultrasound (US) images obtained by the Koelis Urostation™. Materials and Methods We prospectively included 15 consecutive patients referred for placement of intraprostatic fiducials before radiotherapy and who gave written informed consent by signing the Institutional Review Board-approved forms. Three fiducials were placed in the prostate under US guidance in standardized positions (right apex, left mid-gland, right base) using the Koelis Urostation™. Patients then underwent prostate MR imaging. Four operators outlined the prostate on MR and US images and an elastic fusion was retrospectively performed. Fiducials were used to measure the overall target registration error (TRE3D), the error along the antero-posterior (TREAP), right-left (TRERL) and head-feet (TREHF) directions, and within the plane orthogonal to the virtual biopsy track (TRE2D). Results Median TRE3D and TRE2D were 3.8–5.6 mm, and 2.5–3.6 mm, respectively. TRE3D was significantly influenced by the operator (p = 0.013), fiducial location (p = 0.001) and 3D axis orientation (p<0.0001). The worst results were obtained by the least experienced operator. TRE3D was smaller in mid-gland and base than in apex (average difference: -1.21 mm (95% confidence interval (95%CI): -2.03; -0.4) and -1.56 mm (95%CI: -2.44; -0.69) respectively). TREAP and TREHF were larger than TRERL (average difference: +1.29 mm (95%CI: +0.87; +1.71) and +0.59 mm (95%CI: +0.1; +0.95) respectively). Conclusions Registration error values were reasonable for clinical practice. The co-registration accuracy was significantly influenced by the operator’s experience, and significantly poorer in the antero-posterior direction and at the apex.

Technique of Injection of Hyaluronic Acid as a Prostatic Spacer and Fiducials Before Hypofractionated External Beam Radiotherapy for Prostate Cancer

OBJECTIVE To describe a technique combining the implantation of fiducials and a prostatic spacer (hyaluronic acid [HA]) to decrease the rectal toxicity after an image-guided external beam radiotherapy (EBRT) with hypofractionation for prostate cancer and to assess the tolerance and the learning curve of the procedure. MATERIALS AND METHODS Thirty patients with prostate cancer at low or intermediate risk were included in a phase II trial: image-guided EBRT of 62 Gy in 20 fractions of 3.1 Gy with intensity-modulated radiotherapy. A transrectal implantation of 3 fiducials and transperineal injection of 10 cc of HA (NASHA gel spacer, Q-Med AB, Uppsala, Sweden) between the rectum and the prostate was performed by 1 operator. The thickness of HA was measured at 10 points on magnetic resonance imaging to establish a quality score of the injection (maximum score = 10) and determine the learning curve of the procedure. RESULTS The quality score increased from patients 1-10, 11-20, to 21-30 with respective median scores: 7 [2-10], 5 [4-7], and 8 [3-10]. The average thicknesses of HA between the base, middle part, and apex of the prostate and the rectum were the following: 15.1 mm [6.4-29], 9.8 mm [5-21.2], and 9.9 mm [3.2-21.5]. The injection of the HA induced a median pain score of 4 [1-8] and no residual pain at mid-long term. CONCLUSION Creating an interface between the rectum and the prostate and the implantation of fiducials were feasible under local anesthesia with a short learning curve and could become a standard procedure before a hypofractionated EBRT for prostate cancer.

Injection of Hyaluronic Acid (HA) to Better Preserve the Rectal Wall in Prostate Hypofractionated Radiation Therapy (HFR)

202 Background: Several studies are in favor of an α/β ratio of less than 3Gy for prostate (P) cancer, encouraging HFR. However, the development of such radiation patterns can only be done if the risk of rectal toxicity is well controlled. The objective of the present study was to evaluate the contribution of an injection of HA between the rectum and the P to reduce the risk of rectal toxicity in a HFR approach. METHODS A phase II study of HFR at 62Gy in 20 fractions (BED = 84Gy; α / β = 1.5Gy) is currently conducted. A transperineal injection of 10cc of HA (NASHA Spacer gel, Q-Med AB, Uppsala, Sweden) is systematically performed, between the rectum and the P, under local anesthesia and under ultrasound guidance. A dosimetric CT scan is performed before (CT1) and after injection (CT2). Patients are treated with a 7 beams IMRT plan, optimized on the CT2. For the first 10 patients included in the study, the same treatment plan was optimized on CT1. The rectum was empty on the 2 CTs and defined from 2cm above the seminal vesicles to 2 cm below the P. The rectal wall was defined by an internal expansion of 5 mm. The volumes of rectum irradiated, with and without HA, were compared on the following dosimetric parameters: maximum dose (D max), dose to 2.5cc (D2.5), 5cc (D5) and 10cc (D10) of rectal wall and volume of rectum receiving 90% (V90), 80% (V80) and 70% (V70) of the prescribed dose of 62Gy. To limit a potential impact of variation of rectal volume between the two CT, all results are given in cc and not in % of volume. RESULTS The mean P volume was 52.4cc (30cc - 93.8cc) on the CT1 and 52cc (32.5 - 92.7) on the CT2. The injection of HA reduced the mean D max value to the rectal wall of 4.5Gy (57.5Gy vs 62 Gy). The mean values of V90, V80, and V70 are reduced by 69% (1.9cc vs 6.1cc), 46% (4.5cc vs 8.4cc) and 32% (7.4cc vs 10.9cc). Same way, the average values of D2.5, D5 and D10 are reduced by 6.2 Gy (54.6Gy vs 60.8Gy) 9.3Gy (49.0Gy vs 58.3Gy) and 7.8Gy (39.7Gy vs 47.5Gy). CONCLUSIONS In this study, the injection of HA limited the doses to the rectal wall. These results suggest that late toxicities could be significantly reduced. A phase II study is underway to assess the rate of late rectal toxicities when a HFR at 62Gy in 20 fractions is combined with an injection of HA.