PhaseⅠ/Ⅱtrial evaluating concurrent carbon-ion radiotherapy plus chemotherapy for salvage treatment of locally recurrent nasopharyngeal carcinoma

Background: After deinitive chemoradiotherapy for non-metastatic nasopharyngeal carcinoma(NPC), more than 10% of patients will experience a local recurrence. Salvage treatments present signiicant challenges for locally recurrent NPC. Surgery, stereotactic ablative body radiotherapy, and brachytherapy have been used to treat locally recurrent NPC. However, only patients with small-volume tumors can beneit from these treatments. Re-irradiation with X-ray—based intensity-modulated radiotherapy(IMXT) has been more widely used for salvage treatment of locally recurrent NPC with a large tumor burden, but over-irradiation to the surrounding normal tissues has been shown to cause frequent and severe toxicities. Furthermore, locally recurrent NPC represents a clinical entity that is more radioresistant than its primary counterpart. Due to the inherent physical advantages of heavy-particle therapy, precise dose delivery to the target volume(s), without exposing the surrounding organs at risk to extra doses, is highly feasible with carbon-ion radiotherapy(CIRT). In addition, CIRT is a high linear energy transfer(LET) radiation and provides an increased relative biological efectiveness compared with photon and proton radiotherapy. Our prior work showed that CIRT alone to 57.5 Gy E(gray equivalent), at 2.5 Gy E per daily fraction, was well tolerated in patients who were previously treated for NPC with a deinitive dose of IMXT. The short-term response rates at 3–6 months were also acceptable. However, no patients were treated with concurrent chemotherapy. Whether the addition of concurrent chemotherapy to CIRT can beneit locally recurrent NPC patients over CIRT alone has never been addressed. It is possible that the beneits of high-LET CIRT may make radiosensitizing chemotherapy unnecessary. We therefore implemented a phase I/II clinical trial to address these questions and present our methodology and results.Methods and design: The maximal tolerated dose(MTD) of re-treatment using raster-scanning CIRT plus concurrent cisplatin will be determined in the phase I, dose-escalating stage of this study. CIRT dose escalation from 52.5 to 65 Gy E(2.5 Gy E × 21–26 fractions) will be delivered, with the primary endpoints being acute and subacute toxicities. Eicacy in terms of overall survival(OS) and local progression-free survival of patients after concurrent chemotherapy plus CIRT at the determined MTD will then be studied in the phase II stage of the trial. We hypothesize that CIRT plus chemotherapy can improve the 2-year OS rate from the historical 50% to at least 70%.Conclusions: Re-treatment of locally recurrent NPC using photon radiation techniques, including IMXT, provides moderate eicacy but causes potentially severe toxicities. Improved outcomes in terms of eicacy and toxicity proile are expected with CIRT plus chemotherapy. However, the MTD of CIRT used concurrently with cisplatin-based chemotherapy for locally recurrent NPC remains to be determined. In addition, whether the addition of chemotherapy to CIRT is needed remains unknown. These questions will be evaluated in the dose-escalating phase I and randomized phase II trials.

Carbon ion radiotherapy boost in the treatment of glioblastoma:a randomized phase Ⅰ/Ⅲ clinical trial

Background: Glioblastoma (GBM) is a highly virulent tumor of the central nervous system, with a median survival < 15 months. Clearly, an improvement in treatment outcomes is needed. However, the emergence of these malignancies within the delicate brain parenchyma and their infiltrative growth pattern severely limit the use of aggressive local therapies. The particle therapy represents a new promising therapeutic approach to circumvent these prohibitive conditions with improved treatment efficacy. Methods and design: Patients with newly diagnosed malignant gliomas will have their tumor tissue samples submitted for the analysis of the status of O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation. In Phase I, the patients will undergo an induction carbon ion radiotherapy (CIRT) boost followed by 60 GyE of proton irradiation with concurrent temozolomide (TMZ) at 75 mg/m2. To determine the maximal dose of safe induction boost, the tolerance, and acute toxicity rates in a dose-escalation manner from 9 to 18 GyE in three fractions will be used. In Phase III, GBM-only patients will be randomized to receive either 60 GyE (2 GyE per fraction) of proton irradia-tion with concurrent TMZ (control arm) or a CIRT boost (dose determined in Phase I of this trial) followed by 60 GyE of proton irradiation with concurrent TMZ. The primary endpoints are overall survival (OS) and toxicity rates (acute and long-term). Secondary endpoints are progression-free survival (PFS), and tumor response (based upon assess-ment with C-methionine/fluoro-ethyl-tyrosine positron emission tomography [MET/FET PET] or magnetic resonance imaging [MRI] and detection of serologic immune markers). We hypothesize that the induction CIRT boost will result in a greater initial tumor-killing ability and prime the tumor microenvironment for enhanced immunologic tumor clearance, resulting in an expected 33% improvement in OS rates. Discussion: The prognosis of GBM remains grim. The mechanism underpinning the poor prognosis of this malig-nancy is its chronic state of tumor hypoxia, which promotes both immunosuppression/immunologic evasion and radio-resistance. The unique physical and biological properties of CIRT are expected to overcome these microenviron-mental limitations to confer an improved tumor-killing ability and anti-tumor immune response, which could result in an improvement in OS with minimal toxicity. Trial registration number This trial has been registered with the China Clinical Trials Registry, and was allocated the number ChiCTR-OID-17013702.

Fe3O4 nanoparticles as a saturable absorber for a tunable Q-switched dysprosium laser around 3μm

We demonstrate for the first time to our knowledge the use of Fe3O4 nanoparticles for Q-switching a tunable midinfrared(Mid-IR)Dy^3+-doped ZBLAN fiber laser around 3μm.The Q-switcher was fabricated by depositing the prepared Fe3O4 nanoparticles solution onto an Au mirror.Its nonlinear optical response was characterized using a mode locked Ho^3+/Pr^3+-codoped ZBLAN fiber laser at 2.87μm,and showed a modulation depth of 11.9%as well as a saturation intensity of 1.44 MW/cm^2.Inserting the device into a tunable Dy^3+-doped ZBLAN fiber laser,stable Q-switched pulses within the tunable range of 2812.4-3031.6 nm were obtained.When tuning the wavelength to 2931.2 nm,a maximum Q-switching output power of 111.0 mW was achieved with a repetition rate of 123.0 kHz and a pulse width of 1.25μs.The corresponding pulse energy was 0.90μJ.This demonstration suggests that Fe3O4 nanoparticles are a promising broadband saturable absorption material for mid-infrared operation.