Avasopasem manganese synergizes with hypofractionated radiation to ablate tumors through the generation of hydrogen peroxide.

Avasopasem manganese (AVA or GC4419), a selective superoxide dismutase mimetic, is in a phase 3 clinical trial (NCT03689712) as a mitigator of radiation-induced mucositis in head and neck cancer based on its superoxide scavenging activity. We tested whether AVA synergized with radiation via the generation of hydrogen peroxide, the product of superoxide dismutation, to target tumor cells in preclinical xenograft models of non-small cell lung cancer (NSCLC), head and neck squamous cell carcinoma, and pancreatic ductal adenocarcinoma. Treatment synergy with AVA and high dose per fraction radiation occurred when mice were given AVA once before tumor irradiation and further increased when AVA was given before and for 4 days after radiation, supporting a role for oxidative metabolism. This synergy was abrogated by conditional overexpression of catalase in the tumors. In addition, in vitro NSCLC and mammary adenocarcinoma models showed that AVA increased intracellular hydrogen peroxide concentrations and buthionine sulfoximine- and auranofin-induced inhibition of glutathione- and thioredoxin-dependent hydrogen peroxide metabolism selectively enhanced AVA-induced killing of cancer cells compared to normal cells. Gene expression in irradiated tumors treated with AVA suggested that increased inflammatory, TNFα, and apoptosis signaling also contributed to treatment synergy. These results support the hypothesis that AVA, although reducing radiotherapy damage to normal tissues, acts synergistically only with high dose per fraction radiation regimens analogous to stereotactic ablative body radiotherapy against tumors by a hydrogen peroxide-dependent mechanism. This tumoricidal synergy is now being tested in a phase I-II clinical trial in humans (NCT03340974).

Adjuvant Chemotherapy in Rectal Cancer Patients Treated With Preoperative Chemoradiation and Total Mesorectal Excision: A Multicenter and Retrospective Propensity-Score Matching Study.

PURPOSE: The role of adjuvant chemotherapy after preoperative chemoradiation therapy (CRT) and curative surgery in rectal cancer has yet to be definitely determined. We performed a retrospective and multicenter study to evaluate whether adjuvant chemotherapy (AC) could reduce recurrence and improve survival in locally advanced rectal cancer. METHODS AND MATERIALS: We analyzed data from 8 tertiary institutions for 1442 patients with rectal cancer who underwent preoperative CRT and total mesorectal excision. Patients were classified into 2 groups: the AC group (patients who received chemotherapy after surgery) and the observation group (those who did not receive chemotherapy after surgery). Propensity-score matching was used to assess the exact role of AC. The AC group was then subdivided to investigate the impact of adding oxaliplatin to 5-fluorouracil (5-FU). Group 1 was treated with 5-FU/folinic acid or capecitabine without oxaliplatin, and group 2 received 5-FU/folinic acid or capecitabine with oxaliplatin. RESULTS: The 3-year relapse-free survival rates in the AC and observation groups were 85.9% and 84.3%, respectively (P = .532). The 3-year overall survival rates in the AC and observation groups were 94.9% and 89.9%, respectively (P = .123). The rates of locoregional recurrence (2.2% vs 3.2%, P = .294) and distant metastasis (12.4% vs 12.9%, P = .927) at 3 years were not significantly different between the two groups. The 3-year relapse-free survival rates of group 1 and group 2 were 71.5% and 74.8%, respectively (P = .426). The 3-year overall survival rates of group 1 and group 2 were 89.9% and 96.5%, respectively (P = .102). CONCLUSIONS: This multicenter study found insufficient evidence to support the use of 5-FU-based AC after preoperative CRT and curative surgery in rectal cancer.

Adjuvant chemoradiotherapy instead of revision radical resection after local excision for high-risk early rectal cancer.

BACKGROUND: After local excision of early rectal cancer, revision radical resection is recommended for patients with high-risk pathologic stage T1 (pT1) or pT2 cancer, but the revision procedure has high morbidity rates. We evaluated the efficacy of adjuvant concurrent chemoradiotherapy (CCRT) for reducing recurrence after local excision in these patients. METHODS: Eighty-three patients with high-risk pT1 or pT2 rectal cancer underwent postoperative adjuvant CCRT after local excision. We defined high-risk features as pT1 having tumor size ≤3 cm, and/or resection margin (RM) ≤3 mm, and/or lymphovascular invasion (LVI), and/or non-full thickness excision such as endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD), or unknown records regarding those features, or pT2 cancer. Radiotherapy was administered with a median dose of 50.4 Gy in 1.8 Gy fraction size over 5-7 weeks. Concurrent 5-fluorouracil and leucovorin were administered for 4 days in the first and fifth weeks of radiotherapy. RESULTS: The median interval between local excision and radiotherapy was 34 (range, 11-104) days. Fifteen patients (18.1 %) had stage pT2 tumors, 22 (26.5 %) had RM of ≥3 mm, and 21 (25.3 %) had tumors of ≥3 cm in size. Thirteen patients (15.7 %) had LVI. Transanal excision was performed in 58 patients (69.9 %) and 25 patients (30.1 %) underwent EMR or ESD. The median follow-up was 61 months. The 5-year overall survival (OS), locoregional relapse-free survival (LRFS), and disease-free survival (DFS) rates for all patients were 94.9, 91.0, and 89.8 %, respectively. Multivariate analysis did not identify any significant factors for OS or LRFS, but the only significant factor affecting DFS was the pT stage (p = 0.027). CONCLUSIONS: In patients with high-risk pT1 rectal cancer, adjuvant CCRT after local excision could be an effective alternative treatment instead of revision radical resection. However, patients with pT2 stage showed inferior DFS compared to pT1.

A prospective phase 2 multicenter study for the efficacy of radiation therapy following incomplete transarterial chemoembolization in unresectable hepatocellular carcinoma.

PURPOSE: The purpose of this study was to investigate the efficacy and toxicity of radiation therapy (RT) following incomplete transarterial chemoembolization (TACE) in unresectable hepatocellular carcinoma (HCC). METHODS AND MATERIALS: The study was designed as a prospective phase 2 multicenter trial. Patients with unresectable HCC, who had viable tumor after TACE of no more than 3 courses, were eligible. Three-dimensional conformal RT (3D-CRT) was added for HCC treatment with incomplete uptake of iodized oil, and the interval from TACE to RT was 4 to 6 weeks. The primary endpoint of this study was the tumor response after RT following incomplete TACE in unresectable HCC. Secondary endpoints were patterns of failure, progression-free survival (PFS), time to tumor progression (TTP), overall survival (OS) rates at 2 years, and treatment-associated toxicity. Survival was calculated from the start of RT. RESULTS: Between August 2008 and December 2010, 31 patients were enrolled. RT was delivered at a median dose of 54 Gy (range, 46-59.4 Gy) at 1.8 to 2 Gy per fraction. A best objective in-field response rate was achieved in 83.9% of patients, with complete response (CR) in 22.6% of patients and partial response in 61.3% of patients within 12 weeks post-RT. A best objective overall response rate was achieved in 64.5% of patients with CR in 19.4% of patients and PR in 45.1% of patients. The 2-year in-field PFS, PFS, TTP, and OS rates were 45.2%, 29.0%, 36.6%, and 61.3%, respectively. The Barcelona Clinic liver cancer stage was a significant independent prognostic factor for PFS (P=.023). Classic radiation-induced liver disease was not observed. There were no treatment-related deaths or hepatic failure. CONCLUSIONS: Early 3D-CRT following incomplete TACE is a safe and practical treatment option for patients with unresectable HCC.

Long-term follow-up of preoperative pelvic radiation therapy and concomitant boost irradiation in locally advanced rectal cancer patients: a multi-institutional phase II study (KROG 04-01).

PURPOSE: To perform a prospective phase II study to investigate the efficacy and safety of preoperative pelvic radiation therapy and concomitant small-field boost irradiation with 5-fluorouracil and leucovorin for 5 weeks in locally advanced rectal cancer patients. METHODS AND MATERIALS: Sixty-nine patients with locally advanced, nonmetastatic, mid-to-lower rectal cancer were prospectively enrolled. They had received preoperative chemoradiation therapy and total mesorectal excision. Pelvic radiation therapy of 43.2 Gy in 24 fractions plus concomitant boost radiation therapy of 7.2 Gy in 12 fractions was delivered to the pelvis and tumor bed for 5 weeks. Two cycles of 5-fluorouracil and leucovorin were administered for 3 days in the first and fifth week of radiation therapy. The pathologic response, survival outcome, and treatment toxicity were evaluated for the study endpoints. RESULTS: Of 69 patients, 8 (11.6%) had a pathologically complete response. Downstaging rates were 40.5% for T classification and 68.1% for N classification. At the median follow-up of 69 months, 36 patients have been followed up for more than 5 years. The 5-year disease-free survival (DFS) and overall survival rates were 66.0% and 75.3%, respectively. Higher pathologic T (P=.045) and N (P=.032) classification were significant adverse prognostic factors for DFS, and high-grade histology was an adverse prognostic factor for both DFS (P=.025) and overall survival (P=.031) on the multivariate analysis. Fifteen patients (21.7%) experienced grade 3 or 4 acute toxicity, and 7 patients (10.1%) had long-term toxicity. CONCLUSION: Preoperative pelvic radiation therapy with concomitant boost irradiation with 5-fluorouracil and leucovorin for 5 weeks showed acceptable acute and long-term toxicities. However, the benefit of concomitant small-field boost irradiation for 5 weeks in rectal cancer patients was not demonstrated beyond conventional irradiation for 6 weeks in terms of tumor response and survival.