Gimeracil sensitizes cells to radiation via inhibition of homologous recombination

Neoadjuvant therapy with intensity-modulated radiotherapy combined with S-1 for borderline-resectable pancreatic cancer

AIM

We evaluated the efficacy of neoadjuvant chemotherapy with intensity-modulated radiotherapy (NAC-IMRT) in patients with borderline-resectable pancreatic cancer (BRPC).

METHODS

BRPC patients were treated with IMRT (45 Gy/15fr) combined with two courses of S-1 (40 mg/m2 bid) before surgery. Outcomes after NAC-IMRT, surgery, and survival were then evaluated. This single-center retrospective study assessed 26 consecutive patients.

RESULTS

Twenty-six patients (BR-PV: 7, BR-A: 19) with a median age of 73 years were enrolled from 2016 to 2021. Ten (38%) patients were 75-years-old and above. Twenty-three patients completed NAC-IMRT treatment. The median reductions in tumor size and cancer antigen 19-9 level were 13.6% and 69%, respectively. All 26 patients underwent resection within a median time of 71 days after NAC-IMRT initiation. R0 resection was achieved in 24 patients (92%). The median overall survival (OS) was 28.0 months, and the 1- and 3-year OS rates were 100% and 34%, respectively. The median progression-free survival (PFS) was 12.5 months, and the 1- and 3-year PFS rates were 50% and 32%, respectively. No significant differences were observed in OS between the patients under and over the age of 75 (29 vs. 20 months, p = 0.86). The 12 patients who completed NAC-IMRT, resection, and subsequent adjuvant chemotherapy (AC) exhibited a 3-year survival rate of 73%, which was significantly better than that of the patients who did not receive or complete AC (median OS, not reached vs. 19 months, p < 0.001).

CONCLUSION

NAC-IMRT showed outstanding clinical efficacy with acceptable tolerability in patients with BRPC, including geriatric patients.

Moderately hypo-fractionated radiotherapy combined with S-1 in inoperable locally advanced esophageal squamous cell carcinoma: A prospective, single-arm phase II study (GASTO-1045)

Purpose

We launched this prospective phase II single-arm trial on the combination of moderately hypo-fractionated radiotherapy and S-1, to explore the safety and efficacy of the new potent regimen in inoperable locally advanced esophageal squamous carcinoma (LA-ESCC) patients.

Methods

Patients with unresectable stage II-IVB LA-ESCC (UICC 2002, IVB only with metastatic celiac or supraclavicular lymph nodes) were included. Moderately hypofractionated radiotherapy (60Gy in 24 fractions) concurrent with S-1 was delivered. Meanwhile, gastrostomy tube placement by percutaneous endoscopic gastrostomy (PEG) was performed to provide nutritional support. Nutritional supplements were prescribed to meet requirements. The study outcomes included objective response rate (ORR), progression-free survival (PFS), overall survival (OS), locoregional progression-free survival (LRPFS), distant metastasis-free survival (DMFS), failure pattern, toxicities, nutritional status and treatment compliance. Endoscopy was routinely performed during post-treatment follow-up.

Results

Fifty-eight patients were included with a median follow-up of 24.4 months. The median age was 63 years (range 49-83 years) and 42 patients (72.4%) had stage III or IV diseases. The ORR was 91.3% and the CR rate was 60.3%. The estimated 2-year PFS rate and 2-year OS rate was 44.2% (95% confidence interval (CI), 31.3-57.1%) and 71.4% (95% CI, 59.4-83.4%), respectively. Radiation-induced esophagitis was the most common non-hematologic toxicity and 5 patients (8.6%) developed grade≥3 esophagitis. While, with PEG nutrition support, the nutrition-related indicators presented a clear trend toward a gradual improvement. Treatment-related death was not observed.

Conclusions

The moderately hypo-fractionated radiotherapy combined with S-1 showed promising loco-regional disease control and survival benefit in inoperable LA-ESCC patients. Meanwhile, favorable nutritional status and low incidence of severe radiation-induced esophagitis were observed with PEG nutritional support. Moreover, endoscopy examination contributed to the early detection of recurrent esophageal lesions and timely salvage treatment. The efficacy and toxicity of the combined regimen deserved further evaluation.

Trial registration

Clinicaltrials.gov, identifier NCT03660449.

Definitive radiotherapy with stereotactic or IMRT boost with or without radiosensitization strategy for operable breast cancer patients who refuse surgery

For breast cancer (BC) patients who refused surgery, we developed a definitive treatment employing modern sophisticated radiation techniques. Thirty-eight operable BC patients were treated by conventionally fractionated whole-breast (WB) radiotherapy in combination with stereotactic (for primary tumor) or intensity-modulated (for primary tumor with/without regional lymph nodes [LN]) radiotherapy (IMRT) boost. Standard doses were 50 Gy/25 fractions, 21 Gy/3 fractions and 20 Gy/8 fractions, respectively, for the three radiation modalities. Disease stages were 0 (ductal carcinoma in situ [DCIS]) in seven patients, I in 12, II in 16 and III in three. In 26 patients, intratumoral hydrogen peroxide injection or hyperthermia with oral tegafur-gimeracil-oteracil potassium (S-1) was also used to sensitize the tumors to radiation. Hormonal and standard systemic therapy were administered in 25 and 13 patients, respectively. Complete and partial responses were obtained in 19 patients each; in patients with partial response, no further regrowth of the residual mass was observed, except for two patients who developed local recurrence. During a follow-up of 8-160 months (median, 50 months for living patients), two, one and two patients developed local relapse, sub-clavicular node metastasis and distant metastasis, respectively. The 5-year rates for overall, progression-free and local relapse-free survival were 97.2, 90.9 and 93.4%, respectively. Fourteen patients developed Grade 3 radiation dermatitis but all recovered after treatment. In 47%, the affected breast became better-rounded, and the nipple of the irradiated breast became higher by ≥1 cm than the contralateral nipple. Our method might be a treatment option for operable BC patients.

S-1 + Cisplatin with Concurrent Radiotherapy Followed by Surgery for Stage IIIA (N2) Lung Squamous Cell Carcinoma: Results of a Phase II Trial

BACKGROUND

To date, no clinical trials on the use of induction therapy before surgery have focused solely on lung squamous cell carcinoma (LSCC). We report the results of the Personalized Induction Therapy-2 (PIT-2) trial, a multicenter phase II study, performed to investigate the efficacy and safety of S-1 + cisplatin with concurrent thoracic radiotherapy (TRT) followed by surgery in patients with stage IIIA (N2) LSCC.

METHODS

Patients with pathologically proven stage IIIA (N2) LSCC received induction therapy comprising three cycles of S-1 + cisplatin with concurrent TRT (45 Gy in 25 fractions) followed by surgery. S-1 was administered orally at a dose of 40 mg/m² twice daily on days 1-14, in addition to intravenous infusion of cisplatin (60 mg/m²) on day 1. The primary endpoint was 2-year progression-free survival (PFS) rate.

RESULTS

Of 45 registered patients, 43 underwent induction therapy. Of the 43 patients, 39 (91%) underwent surgery (35 lobectomies, 3 pneumonectomies, and 1 wedge resection). The 2-year PFS, 2-year overall survival, objective response rate, and pathological complete response rates were 67% (90% confidence interval [CI] 54-78%), 70% (95% CI 53-81%), 86% (95% CI 76-96%), and 39% (95% CI 23-54%), respectively. No new treatment-related adverse events occurred during the induction therapy. One case of 90-day postoperative mortality involving a patient who underwent right pneumonectomy and developed pneumonia after discharge occurred.

CONCLUSIONS

Induction therapy using S-1 + cisplatin with concurrent TRT followed by surgery is a feasible and promising treatment approach for stage IIIA (N2) LSCC.

Arterial Administration of DNA Crosslinking Agents with Restraint of Homologous Recombination Repair by Intravenous Low-Dose Gemcitabine Is Effective for Locally Advanced Pancreatic Cancer

Simple Summary

Pancreatic cancer is considered incurable, and most cases are detected in the advanced stages. Establishing a new, effective interventional treatment for advanced pancreatic cancer is a pressing issue. Pretreatment with gemcitabine had a restraining effect on the homologous DNA recombination repair (HRR) of DNA crosslinking, inhibiting the function of Rad51, of which expression is found to be increased in pancreatic cancer. The aim of our prospective study was to assess the potential value of the arterial administration of DNA crosslinking agents after intravenous administration of low-dose gemcitabine for patients with advanced pancreatic cancer. We confirmed, among forty-five patients with unresectable advanced pancreatic cancer, that a patient subgroup of locally advanced pancreatic cancer (LAPC, 10 patients) who underwent these treatment courses successively more than twice in the first 6 months had 33 months of overall survival, 31 months of local progression free survival, and a complete response of 40%. This treatment can be a new treatment option for LAPC.

Abstract

(1) Background: Pretreatment by Rad51-inhibitory substances such as gemcitabine followed by arterial chemotherapy using antineoplastic agents causing DNA crosslink might be more beneficial for patients with locally advanced pancreatic cancers than conventional treatments. The efficacy of arterial administration of DNA crosslinking agents with pretreatment of intravenous low-dose gemcitabine for patients with unresectable locally advanced or metastatic pancreatic cancer (LAPC or MPC) is evaluated. (2) Methods: A single-arm, single-center, institutional review board-approved prospective study was conducted between 2005 and 2015. Forty-five patients (23 LAPC, 22 MPC) were included. Patients received a weekly low dose of gemcitabine intravenously for three weeks followed by arterial administration of mitomycin C and epirubicin hydrochloride at tumor-supplying arteries on the fifth or sixth week. This treatment course was repeated at 1.5-to-2-month intervals. Overall survival (OS), local progression-free survival (LPFS), and therapeutic response were evaluated. LAPC or MPC were divided according to treatment compliance, excellent or poor (1 or 2), to subgroups L1, L2, M1, and M2. (3) Results: OS of LAPC and MPC were 23 months and 13 months, respectively. The OS of LAPC with excellent treatment compliance (subgroup L1, 10 patients) was 33 months with 31 months of LPFS, and four patients (40%) had a complete response (CR). The OS of the L1 subgroup was significantly longer than those of other subgroups L2, M1, and M2, which were 17 months, 17 months, and 8 months, respectively. As Grade 3 adverse effects, severe bone marrow suppression, interstitial pneumonitis, and hemolytic uremic syndrome were observed in six (13.0%), three (6.5%), and three (6.5%) patients, respectively. (4) Conclusions: Arterial DNA crosslinking with the systemic restraint of homologous recombination repair can be a new treatment option for LAPC.

Efficacy of Concurrent Chemoradiotherapy With S-1 vs Radiotherapy Alone for Older Patients With Esophageal Cancer: A Multicenter Randomized Phase 3 Clinical Trial

Importance

Most older patients with esophageal cancer cannot complete the standard concurrent chemoradiotherapy (CCRT). An effective and tolerable chemoradiotherapy regimen for older patients is needed.

Objective

To evaluate the efficacy and toxic effects of CCRT with S-1 vs radiotherapy (RT) alone in older patients with esophageal cancer.

Design, Setting, and Participants

A randomized, open-label, phase 3 clinical trial was conducted at 23 Chinese centers between June 1, 2016, and August 31, 2018. The study enrolled 298 patients aged 70 to 85 years. Eligible participants had histologically confirmed esophageal cancer, stage IB to IVB disease based on the 6th edition of the American Joint Committee on Cancer (stage IVB: only metastasis to the supraclavicular/celiac lymph nodes) and an Eastern Cooperative Oncology Group performance status of 0 to 1. Data analysis was performed from August 1, 2020, to March 10, 2021.

Interventions

Patients were stratified according to age (<80 vs ≥80 years) and tumor length (<5 vs ≥5 cm) and randomly assigned (1:1) to receive either CCRT with S-1 or RT alone.

Main Outcomes and Measures

The primary end point was the 2-year overall survival rate using intention-to-treat analysis.

Results

Of the 298 patients enrolled, 180 (60.4%) were men. The median age was 77 (interquartile range, 74-79) years in the CCRT group and 77 (interquartile range, 74-80) years in the RT alone group. A total of 151 patients (50.7%) had stage III or IV disease. The CCRT group had a significantly higher complete response rate than the RT group (41.6% vs 26.8%; P = .007). Surviving patients had a median follow-up of 33.9 months (interquartile range: 28.5-38.2 months), and the CCRT group had a significantly higher 2-year overall survival rate (53.2% vs 35.8%; hazard ratio, 0.63; 95% CI, 0.47-0.85; P = .002). There were no significant differences in the incidence of grade 3 or higher toxic effects between the CCRT and RT groups except that grade 3 or higher leukopenia occurred in more patients in the CCRT group (9.5% vs 2.7%; P = .01). Treatment-related deaths were observed in 3 patients (2.0%) in the CCRT group and 4 patients (2.7%) in the RT group.

Conclusions and Relevance

In this phase 3 randomized clinical trial, CCRT with S-1 was tolerable and provided significant benefits over RT alone in older patients with esophageal cancer.

Trial Registration

ClinicalTrials.gov Identifier: NCT02813967.

A phase II study of S-1 and cisplatin with concurrent thoracic radiotherapy followed by durvalumab for unresectable, locally advanced non-small-cell lung cancer in Japan (SAMURAI study)

Background:

Based on the results of the PACIFIC study, chemoradiotherapy followed by 1-year consolidation therapy with durvalumab was established as the standard of care for unresectable, locally advanced non-small-cell lung cancer (LA-NSCLC). However, some topics not foreseen in that design can be explored, including progression-free survival (PFS) and overall survival (OS) after the start of chemoradiotherapy, the proportion of patients who proceeded to consolidation therapy with durvalumab, and the optimal chemotherapeutic regimens. In Japan, the combination regimen of S-1 + cisplatin (SP), for which the results of multiple clinical studies have suggested a good balance of efficacy and tolerability, is frequently selected in clinical settings. However, the efficacy and safety of consolidation therapy with durvalumab following this SP regimen have not been evaluated. We therefore planned a multicenter, prospective, single-arm, phase II study.

Methods:

In treatment-naïve LA-NSCLC, two cycles of combination chemotherapy with S-1 (80–120 mg/body, Days 1–14) + cisplatin (60 mg/m², Day 1) will be administered at an interval of 4 weeks, with concurrent thoracic radiotherapy (60 Gy). Responders will then receive durvalumab every 2 weeks for up to 1 year. The primary endpoint is 1-year PFS rate.

Discussion:

Compared with the conventional standard regimen in Japan, the SP regimen is expected to be associated with lower incidences of pneumonitis, esophagitis, and febrile neutropenia, which complicate the initiation of consolidation therapy with durvalumab, and have higher antitumor efficacy during chemoradiotherapy. Therefore, SP-based chemoradiotherapy is expected to be successfully followed by consolidation therapy with durvalumab in more patients, resulting in prolonged PFS and OS. Toxicity and efficacy results of the SP regimen in this study will also provide information important to the future establishment of the concurrent combination of chemoradiotherapy and durvalumab.

Trial registration:

Japan Registry of Clinical Trials, jRCTs031190127, registered 1 November 2019, https://jrct.niph.go.jp/latest-detail/jRCTs031190127

Short-term outcomes of preoperative chemoradiotherapy with S-1 for locally advanced rectal cancer

The purpose of the present study was to evaluate the short-term results of preoperative chemoradiation therapy with S-1 for locally advanced rectal cancer. A total of 32 patients with advanced rectal cancer who had been treated with preoperative chemoradiotherapy with S-1 and underwent surgical resection between May 2012 and December 2019 were analyzed. Advanced rectal cancer of clinical stage II and III was diagnosed in 13 (41%) and 19 (59%) patients, respectively. Therapeutic toxicities of anemia (24 patients; 75%), anal pain (22 patients; 69%) and skin and subcutaneous tissue disorders (19 patients; 59%) were frequently observed in all grades. Grade ≥3 leukopenia, anemia, neutrophil count reduction, platelet count reduction and diarrhea were identified in 2 (6%), 1 (3%), 1 (3%), 1 (3%) and 1 (3%) patients, respectively. A total of 29 patients (91%) completed this therapy without any change to the protocol or dosage. R0 resection was performed in 100% of the patients, and no postoperative mortality was observed. Pathological complete response was observed in 9 cases (28.1%). This therapy can be considered for cases of locally advanced rectal cancer due to its acceptable toxicity and relatively high antitumor effect.

Concurrent chemoradiotherapy using cisplatin and S-1, followed by surgery for stage II/IIIA non-small cell lung cancer

OBJECTIVES

Because chemoradiotherapy using cisplatin and S-1, an oral fluoropyrimidine, is effective for unresectable non-small cell lung cancer (NSCLC), an induction setting was used in a multicenter phase II study (Clinical trial number: UMIN000008205). The correlations of relapse and clinicopathological factors were analyzed.

METHODS

We defined locally advanced NSCLC as pathologically proven chest wall invasion or hilar and/or mediastinal lymph node metastases by endobronchial ultrasound-guided transbronchial needle aspiration. The patients received two courses of S-1 administration for 14 days and intravenous cisplatin injection on day 8. A total dose of 40 Gy radiotherapy was concurrently received. Surgical resection was performed after completion of the treatment.

RESULTS

Of the 23 eligible patients, 18 had stage IIIA and 5 had stage IIB NSCLC. Twenty of the eligible patients (87.0%) completed the regimen. Six (26.1%) complete responses were identified and 12 cases (52.2%) were histopathologically downstaged by induction chemoradiotherapy (ICRT). The 3-year overall survival rate was 58.1% and relapse-free survival (RFS) rate was 52.0%, respectively. Among several clinicopathological parameters, univariate RFS analysis identified that only downstaging was significantly associated with longer RFS times (p = 0.003). The radiological response did not reflect pathological response. When the variables of preoperative pathologically proven N2 metastasis, pathological ICRT effectiveness, and downstaging were included in the Cox proportional hazard modes, only the parameter of downstaging displayed significant hazard ratio (hazard ratio 0.13, p = 0.010).

CONCLUSION

This protocol is considered an option among preoperative therapies and has obvious benefits for pathologically downstaged cases.

CLINICAL TRIAL NUMBER

UMIN000008205.

TRIAL REGISTRATION DATE

June 19, 2012.

Research progress and prospects of esophageal cancer in era of precision medicine

Esophageal cancer (EC) is a common digestive system carcinoma, and China has the highest incidence of EC in the world. The prognosis of EC is poor; the five-year survival rate of EC in developing countries is extremely low because the clinical symptoms are often found too late, which makes the patients cannot be cured. In the era of precision medicine, new concepts and technologies are applied to the screening, diagnosis, and treatment of EC. Therefore, it becomes possible to formulate a personalized and accurate disease prevention and treatment program for each patient, so as to achieve maximum therapeutic effect, minimize side effects, and ultimately achieve the goal of improving the prognosis of EC. This article reviews the recent research progress and prospects of EC in the era of precision medicine with regard to disease screening, diagnosis, and treatment.

A phase II study of S-1 with concurrent radiotherapy in elderly patients with esophageal cancer

Background

Concurrent chemoradiotherapy (CCRT) using conventional platinum-based doublets are often associated with significant incidence of toxic effects in elderly patients with esophageal cancer. We previously reported a phase I trial of CCRT using S-1, an oral 5-fluorouracil derivative, which yielded well safe and active outcomes.

Methods

Patients with histologically confirmed esophageal cancer, who were age of 70 years or older with performance status (PS) score of 0-2 or age of 66 to 69 with PS score of 2, were eligible for this Phase II trial. Radiotherapy was delivered in 1.8 Gy per fraction to a total dose of 54 Gy. Concurrently, S-1 was administered at 70 mg/m² on days 1–14 and 29–42. The primary end point was 2-year overall survival rate.

Results

Thirty patients were enrolled, and 28 patients completed the full course of radiotherapy. No grade 4 toxicity or treatment-related death occurred. The grade 3 toxicities included esophagitis (16.7%), leucopoenia (13.3%), neutropenia (10%), anaemia (3.3%), pneumonitis (3.3%) and fatigue (3.3%). The median progression-free survival time and median survival time was 19 and 24 months, respectively. The 2-year overall survival rate was 45.1%, which exceeded the predefined threshold of 2-year OS 35% and met the primary end point of the study.

Conclusions

The results suggest that CCRT using S-1 is effective with mild toxicity in elderly patients with esophageal cancer. A phase III trial is needed to further evaluate this regimen.

Therapeutic strategies with oral fluoropyrimidine anticancer agent, S-1 against oral cancer

Oral cancer has been recognized as a tumor with low sensitivity to anticancer agents. However, introduction of S-1, an oral cancer agent is improving treatment outcome for patients with oral cancer. In addition, S-1, as a main drug for oral cancer treatment in Japan can be easily available for outpatients. In fact, S-1 exerts high therapeutic effects with acceptable side effects. Moreover, combined chemotherapy with S-1 shows higher efficacy than S-1 alone, and combined chemo-radiotherapy with S-1 exerts remarkable therapeutic effects. Furthermore, we should consider the combined therapy of S-1 and molecular targeting agents right now as these combinations were reportedly useful for oral cancer treatment. Here, we describe our findings related to S-1 that were obtained experimentally and clinically, and favorable therapeutic strategies with S-1 against oral cancer with bibliographic considerations.

Gimeracil enhances the antitumor effect of cisplatin in oral squamous cell carcinoma cells in vitro and in vivo

Gimeracil or 5-chloro-2,4-dihydroxypyridine (CDHP) enhances the antitumor effects of 5-fluorouracil (5-FU) by inhibiting dihydropyrimidine dehydrogenase (DPD), which is involved in the degradation of 5-FU. CDHP, as part of a combination therapy, was also reported to exert a radiosensitizing effect. Therefore, CDHP may have underlying mechanisms of action other than DPD inhibition. The focus of the present study was to investigate the antitumor effects of CDHP and cisplatin (CDDP) combination treatment in vitro and in vivo against oral squamous cell carcinoma (OSCC) tumors. The inhibitory growth effects of CDHP and/or CDDP treatment on SAS and HSC2 cells were examined using an MTT assay. The expression levels of DNA double strand break repair proteins, including Ku70, DNA-dependent-protein kinase catalytic subunit (DNA-PKcs), Rad50 and Rad51 in CDHP and/or CDDP-treated cells were detected using western blotting. Nude mice with SAS or HSC2 tumors were treated with CDHP (administered orally 7 times/week) and/or CDDP (administered by intraperitoneal injection once/week) for 2 weeks. Combined treatment of CDHP and CDDP significantly suppressed the growth of SAS and HSC2 cells in vitro and that of tumors in vivo compared with the effects caused by single drug only or control treatments. Western blotting demonstrated that the expression levels of Ku70, DNA-PKcs, Rad50 and Rad51 were downregulated in cells treated with CDHP and CDDP combination treatment. Immunohistochemistry also identified that the expression of DNA double strand break repair proteins was downregulated in tumors treated with CDHP and CDDP combination treatment compared with that of tumors treated with CDDP alone or control. The results of the current study suggest that CDHP may be responsible for enhancing the antitumor effects of CDDP by suppressing the DNA double strand break repair system. Therefore, the combination of CDHP and CDDP may be a potential effective option for OSCC treatment.

A phase I dose escalation study of S-1 with concurrent radiotherapy in elderly patients with esophageal cancer

BACKGROUND

Concurrent chemoradiotherapy (CRT) with 5-fluorouracil (5-FU) and cisplatin (CDDP) are often associated with significant incidence of toxic effects in elderly patients with esophageal cancer. This phase I trial was designed to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of S-1, an oral 5-FU derivative, when given with radiotherapy in elderly patients.

METHODS

Patients who were age of 70 years or older with histologically confirmed esophageal cancer, and had an Eastern Cooperative Oncology Group (ECOG) score of 0-2 were eligible for this study. Radiotherapy was administered in 1.8 Gy fractions 5 times weekly to a total dose of 54 Gy. S-1 was administered on days 1-14 and 29-42 at the following dosages: 60, 70, and 80 mg/m(2)/day.

TRIAL REGISTRATION

NCT01175447 (ClinicalTrials.gov).

RESULTS

Twelve previously untreated patients were enrolled in this study. No grade 3 or 4 toxicity was observed in six patients treated at the 60 and 70 mg/m(2) dose levels. DLT was observed in four of six patients treated at the 80 mg/m(2) dose level. Two patients developed grade 3 esophagitis, one patient developed grade 3 esophagitis and pneumonitis, and one patient developed grade 3 thrombocytopaenia. Endoscopic complete response (CR) was observed in eight patients (66.7%). The median progression free survival (PFS) was 20 months and median overall survival was 29 months.

CONCLUSIONS

The MTD of S-1 was 80 mg/m(2), and the recommended dose (RD) for phase II studies was 70 mg/m(2). This regimen was well tolerated and active in elderly patients with esophageal cancer, meriting further investigation in phase II studies.

Therapeutic effects of re-radiotherapy combined with S-1 in treatment of recurrent esophageal carcinoma

AIM: To evaluate the efficacy and safety of S-1 combined with three dimensional conformal radiotherapy in the treatment of recurrent esophageal carcinoma after radiotherapy.

METHODS: Sixty-one esophageal carcinoma patients who recurred after they had received radical radiotherapy and were confirmed by pathology were divided into either a study group or a control group according to whether receiving S-1 or not. All patients received three dimensional conformal radiotherapy at 1.8-2.0 Gy each time, 5 fractions a week to a total dose of 45-55 Gy. The patients in the study group received S-1 at a dose of 60 mg/(m²•d) for 14 days, every 3 weeks, totally 6 wk when they started receiving re-radiotherapy. The control group merely received re-radiotherapy.

RESULTS: The complete response rate was 38.7% in the study group, and 26.7% in the control group (P > 0.05). The effective rate was 74.2% in the study group, and 46.7% in the control group (P < 0.05). The 1-, 2- and 3-year survival rates were 54.8%, 38.7% and 16.1% in the study group, and 43.3%, 20.0% and 6.7% in the control group (P < 0.05).

CONCLUSION: For recurrent esophageal carcinoma after radical radiotherapy, S-1 combined with three dimensional conformal radiotherapy can improve the efficacy and prolong survival period without a significant increase in acute adverse effects of radiotherapy.

Mutations in the FHA-domain of ectopically expressed NBS1 lead to radiosensitization and to no increase in somatic mutation rates via a partial suppression of homologous recombination

Ionizing radiation induces DNA double-strand breaks (DSBs). Mammalian cells repair DSBs through multiple pathways, and the repair pathway that is utilized may affect cellular radiation sensitivity. In this study, we examined effects on cellular radiosensitivity resulting from functional alterations in homologous recombination (HR). HR was inhibited by overexpression of the forkhead-associated (FHA) domain-mutated NBS1 (G27D/R28D: FHA-2D) protein in HeLa cells or in hamster cells carrying a human X-chromosome. Cells expressing FHA-2D presented partially (but significantly) HR-deficient phenotypes, which were assayed by the reduction of gene conversion frequencies measured with a reporter assay, a decrease in radiation-induced Mre11 foci formation, and hypersensitivity to camptothecin treatments. Interestingly, ectopic expression of FHA-2D did not increase the frequency of radiation-induced somatic mutations at the HPRT locus, suggesting that a partial reduction of HR efficiency has only a slight effect on genomic stability. The expression of FHA-2D rendered the exponentially growing cell population slightly (but significantly) more sensitive to ionizing radiation. This radiosensitization effect due to the expression of FHA-2D was enhanced when the cells were irradiated with split doses delivered at 24-h intervals. Furthermore, enhancement of radiation sensitivity by split dose irradiation was not seen in contact-inhibited G0/G1 populations, even though the cells expressed FHA-2D. These results suggest that the FHA domain of NBS1 might be an effective molecular target that can be used to induce radiosensitization using low molecular weight chemicals, and that partial inhibition of HR might improve the effectiveness of cancer radiotherapy.

Clinical development of S-1 for non-small cell lung cancer: a Japanese perspective

For more than a decade, S-1 has been investigated aggressively against non-small cell lung cancer (NSCLC) in Japan. Recently, two randomized phase III trials of S-1 combined with cisplatin (CDDP) or carboplatin (CBDCA) compared with the standard platinum doublet chemotherapy were reported. S-1 and CDDP was noninferior to CDDP and DTX in terms of overall survival (OS) (median survival time [MST] 16.1 versus 17.1 months, respectively; hazard ratio [HR] 1.013; 96.4% confidence interval [CI] 0.837-1.227). Noninferiority of S-1 and CBDCA compared with CBDCA and paclitaxel was also confirmed for OS (MST 15.2 versus 13.3 months, respectively; HR 0.928; 99.2% CI 0.671-1.283). The noninferiority design employed an upper CI limit of HR<1.322 in the former trial and HR<1.33 in the latter. S-1 combined with CDDP or CBDCA was thought to be one of the standard platinum doublet regimens in the first-line setting for patients with advanced NSCLC in Japan. Some additional interesting phase I and II studies have been published in Japan. They include studies of S-1 as first-line chemotherapy when combined with nonplatinum agents; as second-line chemotherapy; within chemoradiotherapy for locally advanced disease; and in the postoperative adjuvant setting. This review will also describe the use of S-1 for the treatment of NSCLC in these settings.

Phase I study of oral S-1 and concurrent radiotherapy in patients with head and neck cancer

This study investigated the maximum tolerated dose (MTD) of S-1 with concurrent radiotherapy in patients with head and neck cancer, based on the frequency of dose-limiting toxicities (DLT). S-1 was administered orally at escalating doses from 40 mg/m(2) b.i.d. on the days of delivering radiotherapy, which was given at a total dose of 64-70 Gy in 32-35 fractions over 6-7 weeks. A total of 12 patients (3 patients at 40 mg/m(2), 6 patients at 60 mg/m(2), and 3 patients at 80 mg/m(2)) were enrolled in this trial. At the dose of 80 mg/m(2), two of the three patients developed DLT (Grade 3 anorexia and rhabdomyolysis) due to S-1, so the MTD was determined to be 80 mg/m(2). Among the 12 enrolled patients, 9 (75%) showed a complete response and 3 (25%) showed a partial response. The overall response rate was 100%. The recommended dose of S-1 with concurrent radiotherapy is 60 mg/m(2).

DNA double-strand break repair as determinant of cellular radiosensitivity to killing and target in radiation therapy

Radiation therapy plays an important role in the management of a wide range of cancers. Besides innovations in the physical application of radiation dose, radiation therapy is likely to benefit from novel approaches exploiting differences in radiation response between normal and tumor cells. While ionizing radiation induces a variety of DNA lesions, including base damages and single-strand breaks, the DNA double-strand break (DSB) is widely considered as the lesion responsible not only for the aimed cell killing of tumor cells, but also for the general genomic instability that leads to the development of secondary cancers among normal cells. Homologous recombination repair (HRR), non-homologous end-joining (NHEJ), and alternative NHEJ, operating as a backup, are the major pathways utilized by cells for the processing of DSBs. Therefore, their function represents a major mechanism of radiation resistance in tumor cells. HRR is also required to overcome replication stress – a potent contributor to genomic instability that fuels cancer development. HRR and alternative NHEJ show strong cell-cycle dependency and are likely to benefit from radiation therapy mediated redistribution of tumor cells throughout the cell-cycle. Moreover, the synthetic lethality phenotype documented between HRR deficiency and PARP inhibition has opened new avenues for targeted therapies. These observations make HRR a particularly intriguing target for treatments aiming to improve the efficacy of radiation therapy. Here, we briefly describe the major pathways of DSB repair and review their possible contribution to cancer cell radioresistance. Finally, we discuss promising alternatives for targeting DSB repair to improve radiation therapy and cancer treatment.

Nedaplatin: a cisplatin derivative in cancer chemotherapy

Nedaplatin, a cisplatin analog, has been developed to decrease the toxicities induced by cisplatin, such as nephrotoxicity and gastrointestinal toxicity. The dose of nedaplatin is determined by body surface area, not by the area under the curve (AUC). The recommended therapeutic dose is 80–100 mg/m², although the pharmacokinetic profile of nedaplatin is similar to that of carboplatin. In our preliminary study, there was a favorable correlation between AUC and creatinine clearance (CL), suggesting that renal function should be considered when nedaplatin is administered. Ishibashi’s formula, ie, Dose_NDP = AUC × CL_NDP, where CL_NDP = 0.0738 × creatinine clearance + 4.47, would be predictable and useful for estimating the individual dose of nedaplatin. Several Phase II studies have suggested that nedaplatin might be a useful second analog, especially for patients with non-small cell lung cancer, esophageal cancer, uterine cervical cancer, head and neck cancer, or urothelial cancer. Further, nedaplatin was reported to be a useful chemotherapeutic agent with radiosensitizing properties; however, there is no Phase III study of nedaplatin, neither with chemotherapy nor with concurrent chemoradiotherapy, because nedaplatin is not commonly used throughout the world. Further evaluation in a randomized controlled trial is warranted to demonstrate definitively the activity of nedaplatin.

S-1 plus cisplatin with concurrent radiotherapy for locally advanced non-small cell lung cancer: a multi-institutional phase II trial (West Japan Thoracic Oncology Group 3706)

PURPOSE

To evaluate the combination chemotherapy using oral antimetabolite S-1 plus cisplatin (SP) with concurrent thoracic radiotherapy (RT) followed by the consolidation SP for locally advanced non-small cell lung cancer.

PATIENTS AND METHODS

Patients with stage III non-small cell lung cancer, 20 to 74 years of age, and Eastern Cooperative Oncology Group performance status 0 to 1 were eligible. The concurrent phase consisted of full dose S-1 (orally at 40 mg/m/dose twice daily, on days 1-14) and cisplatin (60 mg/m on day 1) repeated every 4 weeks for two cycles with RT delivered beginning on day 1 (60 Gy/30 fractions over 6 weeks). After SP-RT, patients received an additional two cycles of SP as the consolidation phase.

RESULTS

Fifty-five patients were registered between November 2006 and December 2007. Of the 50 patients for efficacy analysis, the median age was 64 years; male/female 40/10; Eastern Cooperative Oncology Group performance status 0/1, 21/29; clinical stage IIIA/IIIB 18/32; and adenocarcinoma/others 20/30. There were 42 clinical responses including one complete response with an objective response rate of 84% (95% confidence interval [CI], 71-93%). The 1- and 2-year overall survival rates were 88% (95% CI, 75-94%) and 70% (95% CI, 55-81%), respectively. The median progression-free survival was 20 months. Of the 54 patients for safety analysis, common toxicities in the concurrent phase included grade 3/4 neutropenia (26%), thrombocytopenia (9%), and grade 3 esophagitis (9%) and febrile neutropenia (9%). In one patient, grade 3 pneumonitis was observed in the consolidation phase. There were two treatment-related deaths caused by infection in the concurrent phase.

CONCLUSIONS

SP-RT showed a promising efficacy against locally advanced NCSLC with acceptable toxicity.

Effects of depletion of dihydropyrimidine dehydrogenase on focus formation and RPA phosphorylation

Gimeracil, an inhibitor of dihydropyrimidine dehydrogenase (DPYD), partially inhibits homologous recombination (HR) repair and has a radiosensitizing effect as well as enhanced sensitivity to Camptothecin (CPT). DPYD is the target protein for radiosensitization by Gimeracil. We investigated the mechanisms of sensitization of radiation and CPT by DPYD inhibition using DLD-1 cells treated with siRNA for DPYD. We investigated the focus formation of various kinds of proteins involved in HR and examined the phosphorylation of RPA by irradiation using Western blot analysis. DPYD depletion by siRNA significantly restrained the formation of radiation-induced foci of Rad51 and RPA, whereas it increased the number of foci of NBS1. The numbers of colocalization of NBS1 and RPA foci in DPYD-depleted cells after radiation were significantly smaller than in the control cells. These results suggest that DPYD depletion is attributable to decreased single-stranded DNA generated by the Mre11/Rad50/NBS1 complex-dependent resection of DNA double-strand break ends. The phosphorylation of RPA by irradiation was partially suppressed in DPYD-depleted cells, suggesting that DPYD depletion may partially inhibit DNA repair with HR by suppressing phosphorylation of RPA. DPYD depletion showed a radiosensitizing effect as well as enhanced sensitivity to CPT. The radiosensitizing effect of DPYD depletion plus CPT was the additive effect of DPYD depletion and CPT. DPYD depletion did not have a cell-killing effect, suggesting that DPYD depletion may not be so toxic. Considering these results, the combination of CPT and drugs that inhibit DPYD may prove useful for radiotherapy as a method of radiosensitization.

Phase I/II study of preoperative concurrent chemoradiotherapy with S-1 for locally advanced, resectable rectal adenocarcinoma

PURPOSE

To assess the maximum tolerability of a combination of S-1 and preoperative radiotherapy and to evaluate the feasibility and activity in patients with locally advanced rectal cancer.

METHODS

Patients (n = 30) with adenocarcinoma of the middle or lower rectum were enrolled in a phase I (n = 9) and/or phase II (n = 21) trial. A total dose of 45 Gy was delivered in 25 fractions over 5 weeks, and S-1 was orally administered twice a day on days 1-14 and 22-35. Surgical resection was scheduled 4-8 weeks after the completion of chemoradiation.

RESULTS

In phase I, the recommended dose (RD) of S-1 was 80 mg/m(2)/day, and the maximum-tolerated dose was never reached. A total of 27 cases, including the 6 RD cases in phase I, were enrolled in phase II. In phase II, a pathological complete response (pCR) was observed in 6/27 patients (22%), pathological downstaging was observed in 21/27 patients (78%), and a tumor volume reduction of 69 ± 22% was obtained. These results were similar to the previously reported pCR rates of 16-18%, pathological downstaging rates of 49-59%, and tumor volume reduction of 68% after chemoradiotherapy with capecitabine. Grade 3 adverse events consisted of one case of leukopenia (4%), 2 cases of anemia (7%) and 3 cases of diarrhea (11%). Overall, the adverse events were very mild. Hand-foot syndrome was not observed.

CONCLUSION

The efficacy of chemoradiotherapy with S-1 seems to be equivalent to the efficacy reported for chemoradiotherapy with capecitabine, but the adverse events were much milder, although further study is warranted.

A nucleoside anticancer drug, 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (TAS106), sensitizes cells to radiation by suppressing BRCA2 expression

Background

A novel anticancer drug 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (ECyd, TAS106) has been shown to radiosensitize tumor cells and to improve the therapeutic efficiency of X-irradiation. However, the effect of TAS106 on cellular DNA repair capacity has not been elucidated. Our aim in this study was to examine whether TAS106 modified the repair capacity of DNA double-strand breaks (DSBs) in tumor cells.

Methods

Various cultured cell lines treated with TAS106 were irradiated and then survival fraction was examined by the clonogenic survival assays. Repair of sublethal damage (SLD), which indicates DSBs repair capacity, was measured as an increase of surviving cells after split dose irradiation with an interval of incubation. To assess the effect of TAS106 on the DSBs repair activity, the time courses of γ-H2AX and 53BP1 foci formation were examined by using immunocytochemistry. The expression of DNA-repair-related proteins was also examined by Western blot analysis and semi-quantitative RT-PCR analysis.

Results

In clonogenic survival assays, pretreatment of TAS106 showed radiosensitizing effects in various cell lines. TAS106 inhibited SLD repair and delayed the disappearance of γ-H2AX and 53BP1 foci, suggesting that DSB repair occurred in A549 cells. Western blot analysis demonstrated that TAS106 down-regulated the expression of BRCA2 and Rad51, which are known as keys among DNA repair proteins in the homologous recombination (HR) pathway. Although a significant radiosensitizing effect of TAS106 was observed in the parental V79 cells, pretreatment with TAS106 did not induce any radiosensitizing effects in BRCA2-deficient V-C8 cells.

Conclusions

Our results indicate that TAS106 induces the down-regulation of BRCA2 and the subsequent abrogation of the HR pathway, leading to a radiosensitizing effect. Therefore, this study suggests that inhibition of the HR pathway may be useful to improve the therapeutic efficiency of radiotherapy for solid tumors.

Gimeracil, an inhibitor of dihydropyrimidine dehydrogenase, inhibits the early step in homologous recombination

Gimeracil (5-chloro-2, 4-dihydroxypyridine) is an inhibitor of dihydropyrimidine dehydrogenase (DPYD), which degrades pyrimidine including 5-fluorouracil in the blood. Gimeracil was originally added to an oral fluoropyrimidine derivative S-1 to yield prolonged 5-fluorouracil concentrations in serum and tumor tissues. We have already reported that gimeracil had radiosensitizing effects by partially inhibiting homologous recombination (HR) in the repair of DNA double strand breaks. We investigated the mechanisms of gimeracil radiosensitization. Comet assay and radiation-induced focus formation of various kinds of proteins involved in HR was carried out. siRNA for DPYD were transfected to HeLa cells to investigate the target protein for radiosensitization with gimeracil. SCneo assay was carried out to examine whether DPYD depletion by siRNA inhibited HR repair of DNA double strand breaks. Tail moments in neutral comet assay increased in gimeracil-treated cells. Gimeracil restrained the formation of foci of Rad51 and replication protein A (RPA), whereas it increased the number of foci of Nbs1, Mre11, Rad50, and FancD2. When HeLa cells were transfected with the DPYD siRNA before irradiation, the cells became more radiosensitive. The degree of radiosensitization by transfection of DPYD siRNA was similar to that of gimeracil. Gimeracil did not sensitize DPYD-depleted cells. Depletion of DPYD by siRNA significantly reduced the frequency of neopositive clones in SCneo assay. Gimeracil partially inhibits the early step in HR. It was found that DPYD is the target protein for radiosensitization by gimeracil. The inhibitors of DPYD, such as gimeracil, could enhance the efficacy of radiotherapy through partial suppression of HR-mediated DNA repair.

The role of homologous recombination in radiation-induced double-strand break repair

DNA double-strand breaks (DSBs) represent the most biologically significant lesions induced by ionizing radiation (IR). HR is the predominant pathway for repairing one-ended DSBs arising in S-phase when the replication fork encounters single-stranded breaks or base damages. Here, we discuss recent findings that two-ended DSBs directly induced by X- or γ-rays in late S- or G2-phase are repaired predominantly by NHEJ, with HR only repairing a sub-fraction of such DSBs. This sub-fraction represents DSBs which localize to heterochromatic DNA regions and, which in control cells, are repaired with slow kinetics over many hours post irradiation. The observation that defined DSB populations are repaired by either NHEJ or HR suggests an assignment of specific tasks for each of the two processes. Furthermore, heavy ion induced complex DSBs, which are in general more slowly repaired than X- or γ-ray induced breaks, are nearly always repaired by HR independent of chromatin localization suggesting that the speed of repair is an important factor determining the DSB repair pathway usage. Finally, NHEJ and HR can, under certain conditions, also compensate for each other such that DSBs normally repaired by one pathway can undergo repair by the other if genetic failures necessitate the pathway switch.