Combined effects of ionizing radiation and 4-hydroperoxyfosfamide in vitro

A Combination of Radiation and the Hypoxia-Activated Prodrug Evofosfamide (TH-302) is Efficacious against a Human Orthotopic Pancreatic Tumor Model

This study was designed to investigate the effect of single-dose radiation therapy (RT) in combination with evofosfamide (TH-302), a hypoxia-activated prodrug, in a pre-clinical model of pancreatic cancer. AsPC1 tumors were implanted orthotopically in the pancreas of nude mice. Tumors were treated with 15 Gy of RT, using a 1 cm diameter field, and delivered as a continuous arc. Image-guidance to center the field on the tumor was based on CT imaging with intraperitoneal contrast. Evofosfamide (100 mg/kg, i.p.) was administered 3 hours before RT. Tumor volumes were measured using ultrasound, and regrowth curves were plotted. Tumor hypoxia and cell proliferation were measured using pimonidazole and the thymidine analog EdU, respectively. In vitro clonogenic assays were performed. Tumors were shown to contain substantial areas of hypoxia, as calculated by percent pimonidazole staining. Evofosfamide was active in these tumors, as demonstrated by a significant reduction in uptake of the thymidine analog EdU. This effect was visible in oxygenated tissue, consistent with the previously reported bystander effects of evofosfamide. RT produced significant regrowth delay, as did evofosfamide. The combination of both agents produced a growth delay that was at least equal to the sum of the two treatments given separately. The improvement in tumor response when evofosfamide is combined with RT supports the hypothesis that hypoxia is a cause of radioresistance in high dose RT for pancreatic cancer. Assessing the efficacy and safety of stereotactic radiation treatment and evofosfamide is warranted in patients with locally advanced pancreatic cancer.

Chemotherapy of lung cancer: A global perspective of the role of ifosfamide

The oxazaphosphorine cytostatic ifosfamide (IFO) has been successfully integrated in the treatment of various hematological and solid tumors. The purpose of this review is to summarize the evidence for its use in lung cancer starting from basic data of preclinical studies followed by a global summary of the phase III and seminal phase II clinical studies. Global in double respect: first covering both the small cell as well as the non-small cell indications, and, second tracing those studies performed in Europe and the United States as well as those from Asian countries.

Recursive Partitioning Analysis Groups II-III brain metastases of non-small cell lung cancer: a phase II randomized study comparing two concurrent chemoradiotherapy regimens

PURPOSE

To compare the response rates and safety profiles of two investigational chemotherapies that were delivered concurrently with whole-brain radiotherapy in a population of patients with chemonaive non-small cell lung cancer.

METHODS

Eligible patients included those presenting with brain metastases belonging to the Recursive Partitioning Analysis of prognostic factors from the Radiation Therapy Oncology groups II or III, who were not able to undergo surgery or stereotactic radiotherapy. Other main eligibility criteria were age <75 years and Eastern Cooperative Oncology Group performance status = 0 to 2. The study design was as follows: all patients received whole-brain radiotherapy in three split courses of 18 gy/10 fractions. They were randomly (1:1) assigned to regimen A, consisting of a triplet cisplatin-vinorelbine-ifosfomide, or to regimen B, consisting of high-dose single-drug ifosfamide. In both groups, chemotherapy was delivered on a 4-week cycle, for three courses. Each course was delivered concurrently with radiotherapy. Brain and other tumor lesion assessments were performed in both groups at the end of the three courses (RECIST). Neurologic symptoms were evaluated quantitatively at each step of the treatment program. All analyses were carried out in an intention to treat basis, and statistical tests were two sided.

RESULTS

Seventy patients were randomly allocated into groups A (n = 37) and B (n = 33). With regards to the whole lesions, overall response rates did not significantly differ between the groups (group A: 45.9%; group B: 33.3%; chi(2); p = 0.28). When brain-target lesions were separately analyzed, respective response rates were 59.5% and 48.5%; (chi(2); p = 0.0.53). Febrile neutropenia was more frequently observed in the former group (n = 19, 54.29%) than in the latter (n = 12, 36.36%; p = 0.13), and a similar difference was also observed regarding documented infections. Red blood cell transfusions and readmission for antibiotic infusions significantly affected more patients in group A than in group B. The longitudinal evaluation of neurologic symptoms (by means of Generalized Estimating Equation) slightly improved during the treatment program, and there was no difference between the groups. Median overall survival did not significantly differ between the two groups (months [95% confidence interval], 8.5 [6.4-10.8] and 5.7 [4.6-11.9] in groups A B, respectively; p= 0.82). In the Cox model, a high neuron-specific enolase serum level was the only significant prognostic determinant.

CONCLUSION

Both regimens were active and induced a high rate of response, particularly for brain-target lesions. Myelotoxicity jeopardizes the acceptability of both regimens. Despite such an aggressive approach, none of the regimens suggested a putative overall improvement of outcome in this poor prognosis presentation of metastatic non-small cell lung cancer. The search for alternative therapies to chemotherapy, such as targeted therapy, is urgently warranted in this setting.

A multiscale mathematical model of cancer, and its use in analyzing irradiation therapies

Background

Radiotherapy outcomes are usually predicted using the Linear Quadratic model. However, this model does not integrate complex features of tumor growth, in particular cell cycle regulation.

Methods

In this paper, we propose a multiscale model of cancer growth based on the genetic and molecular features of the evolution of colorectal cancer. The model includes key genes, cellular kinetics, tissue dynamics, macroscopic tumor evolution and radiosensitivity dependence on the cell cycle phase. We investigate the role of gene-dependent cell cycle regulation in the response of tumors to therapeutic irradiation protocols.

Results

Simulation results emphasize the importance of tumor tissue features and the need to consider regulating factors such as hypoxia, as well as tumor geometry and tissue dynamics, in predicting and improving radiotherapeutic efficacy.

Conclusion

This model provides insight into the coupling of complex biological processes, which leads to a better understanding of oncogenesis. This will hopefully lead to improved irradiation therapy.

Interaction of pemetrexed disodium (ALIMTA, multitargeted antifolate) and irradiation in vitro

PURPOSE

Pemetrexed disodium (Alimta, multitargeted antifolate, LY231514; Eli Lilly and Co., Indianapolis, Indiana) ("pemetrexed") is a new folate antimetabolite with significant antitumor activity. Different from classic antifolates, pemetrexed inhibits several key enzymes of thymidylate and purine synthesis, but a radiosensitizing potential may also be presumed. Therefore, the interaction of pemetrexed and ionizing radiation was studied for in vitro clonogenic survival of different human tumor cell lines.

METHODS AND MATERIALS

Human colon (Widr), breast (MCF-7), cervix (Hela), and lung (LXI) carcinoma cells from log-phase cultures were exposed to pemetrexed (2 h) in combination with different radiation doses given 1 h before pemetrexed washout (all cell lines) or at different points of time before or after pemetrexed addition (Widr). Survival curves were analyzed according to the linear-quadratic (LQ) model, and mean inactivation doses (MID) and radiation enhancement ratios were calculated from the survival curve parameters. Cell-cycle progression of serum-stimulated and pemetrexed- or mock-treated Widr cells was monitored by flow cytometry.

RESULTS

Radiosensitization was found for all cell lines at moderately toxic pemetrexed exposures (0.05-0.3 microg/ml [106-636 nM]), but this was cell-type dependent and was most pronounced at roughly isotoxic concentrations, for the least pemetrexed-sensitive Widr cells. Enhancement ratios ranged from about 1.2 (MCF-7 and Hela) to 1.8 (Widr), with a tendency to increase with pemetrexed concentration. Little, if any, change of radiosensitization was observed (Widr) when the time of irradiation was varied from 4 h before to 10 h after the beginning of pemetrexed treatment. Cell-cycle progression of serum-stimulated Widr cells was only marginally affected by pemetrexed.

CONCLUSIONS

Pemetrexed enhances radiation-induced cell inactivation at moderately toxic exposures and over many hours after drug removal. This effect is not due to disturbed cell-cycle progression, but likely involves an interaction of pemetrexed with long-lived (>4 h) cellular radiation damage and needs to be considered when introducing a combined clinical application.

Concurrent ifosfamide-based chemotherapy and irradiation. Analysis of treatment-related toxicity in 43 patients with sarcoma

BACKGROUND

The current study was performed to evaluate the toxicity profile of therapeutic doses of ifosfamide (IFX) given concurrently with full-dose external beam radiotherapy (EBRT) in patients with soft tissue and bone sarcomas.

METHODS

The medical records of 43 consecutive patients with soft tissue or bone sarcomas who were treated with concurrent IFX and EBRT were reviewed.

RESULTS

The median patient age was 20 years. Histologies were rhabdomyosarcoma (n = 16 patients), Ewing sarcoma (n = 10 patients), malignant fibrous histiocytoma (n = 9 patients), and other soft tissue sarcomas (n = 8 patients). Thirty-one patients (72%) had localized disease, and 12 patients (28%) had synchronous local and distant disease. Treatment consisted of EBRT (median dose, 50.4 gray [Gy]) with concomitant IFX (median dose per cycle, 10.2 g/m(2)). All patients with Ewing sarcoma or rhabdomyosarcoma received additional concurrent chemotherapy. Twenty-six patients (60%) received two or more cycles of IFX, and 17 patients (40%) were treated with one cycle of IFX and EBRT. The incidences of World Health Organization Grade 3 and Grade 4 toxicities were 29% (21 of 73 cycles) and 22% (16 of 73 cycles), respectively. Grade 4 systemic toxicities included leukopenia (n = 14 patients), neurotoxicity (suicidal ideation; n = 1 patient), and diarrhea (n = 1 patient). Confluent moist desquamation (Grade 3) occurred in nine patients in the treatment field; no patient experienced Grade 4 local toxicity. Among 14 patients who were treated preoperatively, 2 patients (14%) had a pathologic complete response, and 6 patients (43%) had a pathologic near-complete response (> or = 90% necrosis).

CONCLUSIONS

Local and systemic toxicities after the administration of therapeutic doses of IFX with concomitant EBRT appear comparable to those observed with either treatment alone. These results support the design of prospective studies evaluating concurrent ifosfamide and radiation therapy for patients with sarcomas.

Novel approach to in vivo screening for radioprotective activity in whole mice: in vivo electron spin resonance study probing the redox reaction of nitroxyl

Previously, we reported that X-irradiation enhanced the signal decay of a spin probe injected into whole mice measured by in vivo ESR, and that the observed enhancement was suppressed by the pre-administration of cysteamine, a radioprotector [Miura, Y., Anzai, K., Urano, S. and Ozawa, T. (1997) Free Rad. Biol. Med. 23: 533-540]. In the present study, the suppression activity of the X-ray-induced increase in the ESR signal decay rate (termed suppression index, SI) was measured for several radioprotectors: 5-hydroxytryptamine (5-HT), S-2-(3-aminopropylamino)-ethylphosphorothioic acid (WR-2721), 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl (TEMPOL), cimetidine, interleukin-1 beta (IL-1 beta) and stem cell factor (SCF). The enhancement of the ESR signal decay of carbamoyl-PROXYL due to X-irradiation was suppressed by a treatment with all of the radioprotectors examined, showing positive SI values. However, a dose-dependency of 5-HT or WR-2721 was not observed, suggesting that several mechanisms exist for radioprotection and a modification of the signal decay rate. Although the in vivo ESR system cannot be used in place of the 30-day survival method for the assessment of radioprotectors, this system might be applicable to in vivo, non-invasive screening prior to using the 30-day survival method.