Maximizing therapeutic gain with gemcitabine and fractionated radiation

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).

Gemcitabine potentiates the anti-tumour effect of radiation on medullary thyroid cancer

Patients with medullary thyroid cancer (MTC) are often diagnosed with spread tumour disease and the development of better systemic treatment options for these patients is important. Treatment with the radiolabelled somatostatin analogue ¹⁷⁷Lu-octreotate is already a promising option but can be optimised. For example, combination treatment with another substance could increase the effect on tumour tissue. Gemcitabine is a nucleoside analogue that has been shown to sensitise tumour cells to radiation. The aim of this study was to investigate potentially additive or synergistic effects of combining radiation with gemcitabine for treatment of MTC. Nude mice transplanted with patient-derived MTC tumours (GOT2) were divided into groups and treated with radiation and/or gemcitabine. Radiation treatment was given as ¹⁷⁷Lu-octreotate or external beam radiotherapy (EBRT). The volume of treated and untreated tumours was followed. The absorbed dose and amount of gemcitabine were chosen to give moderate tumour volume reduction when given as monotherapy to enable detection of increased effects from combination treatment. After follow-up, the mice were killed and tumours were immunohistochemically (IHC) analysed. Overall, the animals that received a combination of EBRT and gemcitabine showed the largest reduction in tumour volume. Monotherapy with EBRT or gemcitabine also resulted in a clear detrimental effect on tumour volume, while the animals that received ¹⁷⁷Lu-octreotate monotherapy showed similar response as the untreated animals. The GOT2 tumour was confirmed in the IHC analyses by markers for MTC. The IHC analyses also revealed that the proliferative activity of tumour cells was similar in all tumours, but indicated that fibrotic tissue was more common after EBRT and/or gemcitabine treatment. The results indicate that an additive, or even synergistic, effect may be achieved by combining radiation with gemcitabine for treatment of MTC. Future studies should be performed to evaluate the full potential of combining ¹⁷⁷Lu-octreotate with gemcitabine in patients.

Phase I Clinical Trial of Everolimus Combined with Trimodality Therapy in Patients with Muscle-Invasive Bladder Cancer

Background: Local control following trimodality therapy (TMT) for muscle-invasive bladder cancer (MIBC) requires further optimization.

Objective: Evaluating the biologic endpoint, feasibility, and toxicity of integrating everolimus to TMT in patients with MIBC.

Methods: This was a phase I trial in patients with MIBC who were not surgical candidates or who refused cystectomy. Following maximal transurethral tumor resection, patients were treated by radiotherapy (50 Gy/20 fractions), gemcitabine (100 mg/m2/weekly) and escalating doses of everolimus (2.5–5.0 mg/day). Everolimus was given daily for one month prior to radiation, during treatment, and one month post-radiation. Toxicity assessment followed the Radiation Therapy Oncology Group Acute Radiation Morbidity Scoring Criteria. Biologic endpoint with downregulation of phospho-S6 (pS6) was assessed using immunohistochemistry. Local response was evaluated with imaging and bladder biopsy post-therapy.

Results: 10 patients were recruited; 8 males, 2 females. Median age was 78 years (range: 63–85). Four patients entered everolimus 2.5 mg cohort. Six other patients entered everolimus 5.0 mg cohort. Toxicities were encountered in 2 patients (Grade I), 6 patients (Grade II), 9 patients (Grade III) and 1 patient (Grade IV), with some experiencing more than one toxicity. Most Grade III and IV toxicities were encountered from everolimus alone prior to combination testing. Trial was terminated early due to toxicity. Interestingly, 6/10 patients (60%) achieved a complete response with negative post-treatment biopsies. Significant decrease of pS6 was demonstrated post-therapy (p = 0.03).

Conclusions: Although combining everolimus with TMT achieved a biological endpoint and complete response in a significant number of patients with MIBC and negative prognostic factors, it was associated with unacceptable increased toxicity.

Risk of radiation-induced pneumonitis after helical and static-port tomotherapy in lung cancer patients and experimental rats

Background

Radiotherapy (RT) is one of the major non-operative treatment modalities for treating lung cancer. Tomotherapy is an advanced type of intensity-modulated radiotherapy (IMRT) in which radiation may be delivered in a helical fashion. However, unexpected pneumonitis may occur in patients treated with tomotherapy, especially in combination with chemotherapy, as a result of extensive low-dose radiation of large lung volumes. The aim of our study was to investigate the risk of radiation-induced pneumonitis after helical-mode and static-mode tomotherapy in patients with lung cancer and in an animal model.

Method

A total of 63 patients with primary lung cancer who were treated with static or helical tomotherapy with or without concurrent chemoradiotherapy (CCRT) were analyzed. Additionally, rats with radiation-induced pulmonary toxicity, which was induced by the application of helical or static tomography with or without CCRT, were evaluated.

Results

Helical-mode tomotherapy resulted in a significantly higher rate of late radiation pneumonitis in lung cancer patients than static-mode tomotherapy when evaluated by the Radiation Therapy Oncology Group (RTOG) and National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) scoring system. In the animal model, helical tomotherapy alone induced significantly higher expression of interleukin (IL)-1α, IL-1β, IL-6, and transforming growth factor (TGF)-β in lung specimens, especially on the untreated side, compared to static tomotherapy alone. Additionally, rats treated with helical tomotherapy and CCRT demonstrated significantly higher expression of inflammatory cytokines compared to those treated with static tomotherapy and CCRT.

Conclusion

Rat models treated with tomotherapy with or without CCRT could present similar patterns of pulmonary toxicity to those shown in lung cancer patients. The models can be used in further investigations of radiation induced pulmonary toxicity.

Histopathological effects of preoperative chemoradiotherapy for pancreatic cancer: an analysis for the impact of radiation and gemcitabine doses

BACKGROUND AND PURPOSE

Histopathological findings of patients who underwent resection for pancreatic adenocarcinoma (PC) after preoperative chemoradiotherapy (CRT) reportedly showed beneficial effects. The purpose of our study was to evaluate the correlation between histopathological effects (HE) of preoperative CRT and treatment parameters [radiation and gemcitabine (GEM) doses].

MATERIAL AND METHODS

HE of CRT were assessed on 158 primary lesions of 157 patients with PC who underwent pancreatic resection after preoperative CRT with GEM between January 2006 and December 2011. The radiation dose delivered to the primary tumor site and surrounding regional nodal areas was 50 Gy until September 2009 followed by the dose escalation of a 10 Gy boost added for delivery with the field-in-field technique to the roots of the celiac and superior mesenteric arteries. Intravenous administration of GEM (1000 /m(2)) was initiated concurrently on days 1, 8, and 15, every 4 weeks and generally repeated for 3 cycles. HE of CRT on the primary tumor were categorized based on the number of tumor cells destroyed.

RESULTS

The median overall survival time was 74.5 months and 3-year and 5-year survival rates were 64.3% and 54.5%, respectively. Dose-volume parameters of radiation such as D33 with a cut-off value of 51.6 Gy were correlated significantly with HE (p=.0230). Lesions having received GEM>7625 mg/m(2) before surgical resection more frequently showed positive HE (p=.0002). Multivariate logistic regression analysis demonstrated that both D33 and cumulative GEM dose were significant predictors of definite HE (p=.0110 and <.0001, respectively).

CONCLUSIONS

Our retrospective analysis showed that dose intensity of radiation and GEM is significantly related to HE of preoperative CRT for PC.

Phase I trial of radiotherapy concurrent with twice-weekly gemcitabine for head and neck cancer: translation from preclinical investigations aiming to improve the therapeutic ratio

BACKGROUND

Once-weekly gemcitabine concurrent with radiotherapy was highly effective in the treatment of head and neck cancer (HNC) but limited by high mucosal toxicity. Pre-clinical investigations suggested that delivering gemcitabine at substantially lower doses twice weekly during radiotherapy improved the therapeutic ratio. We sought to translated these preclinical findings to a phase I trial.

METHODS

Twenty-five patients with non-resectable HNC were scheduled to receive gemcitabine twice weekly during the last 2 weeks (total 5 infusions) of hyperfractionated radiotherapy delivering 1.2 Gy twice daily to total 76.8 Gy. Tumor biopsies to measure active intracellular (phosphorylated) gemcitabine were planned after the first drug delivery. Patients were assigned to escalating dose cohorts using the Continuous Reassessment Method.

RESULTS

Twenty-one patients evaluable for toxicity were divided into cohorts receiving twice weekly treatment with 10, 20, 33, or 50 mg/m(2) gemcitabine. Dose-limiting toxicity was grade 3-4 confluent mucositis/pharyngitis, and the maximally tolerated dose (MTD) was 20 mg/m(2). Median survival was 20 months, with no difference between cohorts receiving lower (10, 20 mg/m(2)) or higher (33, 50 mg/m(2)) gemcitabine doses. Tumor biopsies after the first drug delivery showed only a minority of tumor cells in the specimens.

CONCLUSION

These findings validate preclinical models that show that gemcitabine is radiation sensitizer at doses far below those used for systemic chemotherapy. However, the improvement in the therapeutic ratio predicted from the preclinical study did not translate into a substantial relative increase in the MTD of the drug in the clinical phase I trial.

Postchemotherapy and tumor-selective targeting with the La-specific DAB4 monoclonal antibody relates to apoptotic cell clearance

Early identification of tumor responses to treatment is crucial for devising more effective and safer cancer treatments. No widely applicable, noninvasive method currently exists for specifically detecting tumor cell death after cytotoxic treatment and thus for predicting treatment outcomes.

METHODS

We have further characterized the targeting of the murine monoclonal antibody DAB4 specifically to dead tumor cells in vitro, in vivo, and in clinical samples. We found that sustained DAB4 binding to treated cells was closely associated with markers of intrinsic apoptosis and DNA double-strand break formation. In a competition binding assay, DAB4 bound EL4 murine thymic lymphoma cells in preference to the normal counterpart of murine thymocytes. Defective in vivo clearance of apoptotic cells augmented in vivo accumulation of DAB4 in tumors particularly after chemotherapy but was unchanged in normal tissues. Tumor targeting of DAB4 was selective for syngeneic murine tumors and for human tumor xenografts of prostate cancer (PC-3) and pancreatic cancer (Panc-1) before and more so after chemotherapy. Furthermore, DAB4 was shown to bind to dead primary acute lymphoblastic leukemic blasts cultured with cytotoxic drugs and dead epithelial cancer cells isolated from peripheral blood of small cell lung carcinoma patients given chemotherapy.

CONCLUSION

Collectively, these results further demonstrate the selectivity of DAB4 for chemotherapy-induced dead tumor cells. This postchemotherapy selectivity is related to a relative increase in the availability of DAB4-binding targets in tumor tissue rather than in normal tissues. The in vitro findings were translated in vivo to human xenograft models and to ex vivo analyses of clinical samples, providing further evidence of the potential of DAB4 as a marker of tumor cell death after DNA-damaging cytotoxic treatment that could be harnessed as a predictive marker of treatment responses.

Preclinical combination therapy of clofarabine plus radiation

Clofarabine, an approved anticancer drug, was evaluated in combination with radiation in six subcutaneously implanted human tumor xenograft models. Clofarabine had no effect on the growth of SF-295 glioblastoma, which was not enhanced by radiation. There was no difference between clofarabine with and without radiation in the DU-145 prostate model. The combined effect on NCI-H460 lung tumors appeared to be additive. SR475 head and neck, PANC-1 pancreatic, and HCT-116 colon tumors were radiomodified by clofarabine. The radiomodifying capacity of clofarabine was superior to that for gemcitabine in two models (PANC-1 and HCT-116) and was comparable in the other four models.

Isolated lung perfusion with gemcitabine combined with radiotherapy: no additional lung toxicity in an experimental model

OBJECTIVES

Isolated lung perfusion with gemcitabine is an effective technique for the treatment of lung metastases in an experimental model. In clinical studies, increased toxicity has been observed when combining intravenous gemcitabine with radiotherapy (RT). The goal of our study was to determine whether RT in combination with isolated lung perfusion increases lung toxicity.

METHODS

Rodents were randomized into eight groups: sham group, RT, intravenous gemcitabine, intravenous gemcitabine combined with RT, isolated lung perfusion with hydroxyethyl starch (HES) or gemcitabine, isolated lung perfusion with HES or gemcitabine combined with RT. Gemcitabine was administered in a dose of 40 mg/kg and RT as a single fraction of 8 Gy. The effect on lung tissue was evaluated by % fibrosis in a haematoxylin-eosin stain and by % alveoli that contained siderophages on Perls stain. A total of 36 slices were made per treatment and per stain. The results of different groups were compared using logistic regression.

RESULTS

There were no significant differences between treatment with intravenous gemcitabine and RT. Isolated lung perfusion with gemcitabine showed significant more histopathologic changes compared with intravenous gemcitabine (P < 0.0001). When RT was added, there was no fibrosis after intravenous gemcitabine and mild-to-moderate haemosiderosis. After isolated lung perfusion with gemcitabine combined with RT, there was moderate to severe fibrosis and mild to severe haemosiderosis. Adding RT to isolated lung perfusion with gemcitabine showed no significant difference compared to isolated lung perfusion alone.

CONCLUSIONS

Combination of isolated lung perfusion and RT is feasible in an experimental model. No additional toxicity of RT was observed compared to isolated lung perfusion alone. Further studies are necessary to determine efficacy of this combined treatment.

Perineural invasion and lymph node involvement as indicators of surgical outcome and pattern of recurrence in the setting of preoperative gemcitabine-based chemoradiation therapy for resectable pancreatic cancer. Ann Surg. 2012;255:95-102. [PMID: 22123160 DOI: 10.1097/sla.0b013e31823d813c]

OBJECTIVE

To analyze the histopathological indicators significantly associated with surgical outcome and the pattern of recurrence in the setting of preoperative gemcitabine-based chemoradiation therapy (CRT) and subsequent pancreatectomy.

BACKGROUND

Clinicopathological assessment of the resected specimen is an indispensable tool for predicting patient prognosis and localizing high-risk sites for tumor relapse. This procedure is also essential for the establishment of efficient postoperative follow-up protocols in the setting of a preoperative CRT strategy.

METHODS

In a prospective phase II clinical trial at our hospital, 110 patients received preoperative CRT and subsequent resection. All 110 resected cases were included in this study. We employed disease-free survival (DFS) as a surgical outcome, and the pattern of recurrence was divided into 2 categories: (1) recurrence in the abdominal cavity (RAC), defined as either a locoregional or a peritoneal recurrence; or (2) distant recurrence (DR), defined as cancer recurrence in a distant organ. Clinicopathological variables were analyzed in association with DFS, RAC, and DR.

RESULTS

Positive nodal involvement and perineural invasion were independent factors that were significantly associated with an unfavorable DFS (P = 0.021 and P = 0.026, respectively). The presence of perineural invasion was the single independent variable significantly associated with an increased risk of RAC (P = 0.002), whereas the status of nodal involvement was the single independent variable significantly associated with an increased risk of DR (P = 0.013).

CONCLUSIONS

The status of nodal involvement and perineural invasion in resected specimens are significantly associated with DFS and clearly predict the pattern of recurrence in the setting of a preoperative gemcitabine-based CRT strategy. This study is registered at UMIN-CTR and carries the ID number UMIN000001804.

Phase I study of radiochemotherapy with gemcitabine in invasive bladder cancer

Tolerability to gemcitabine radiochemotherapy was evaluated in 33 patients with inoperable, locally advanced transitional-cell bladder cancers. The dose of 75 mg/m(2) gemcitabine once a week, concurrently with standard radiotherapy of 60 Gy/6 weeks, was found to be acceptable. Eighty-one percentage of 3-year local progression-free survival suggests efficiency warranting further studies.

Adjuvant gemcitabine alone versus gemcitabine-based chemoradiotherapy after curative resection for pancreatic cancer: a randomized EORTC-40013-22012/FFCD-9203/GERCOR phase II study

PURPOSE

The role of adjuvant chemoradiotherapy (CRT) in resectable pancreatic cancer is still debated. This randomized phase II intergroup study explores the feasibility and tolerability of a gemcitabine-based CRT regimen after R0 resection of pancreatic head cancer.

PATIENTS AND METHODS

Within 8 weeks after surgery, patients were randomly assigned to receive either four cycles of gemcitabine (control arm) or gemcitabine for two cycles followed by weekly gemcitabine with concurrent radiation (50.4 Gy; CRT arm). The primary objective was to exclude a < 60% treatment completion and a > 40% rate of grade 4 hematologic or GI toxicity in the CRT arm with type I and II errors of 10%. Secondary end points were late toxicity, disease-free survival (DFS), and overall survival (OS).

RESULTS

Between September 2004 and January 2007, 90 patients were randomly assigned (45:45). Patient characteristics were similar in both arms. Treatment was completed per protocol by 86.7% and 73.3% (80% CI, 63.1% to 81.9%; 95% CI, 58.1% to 85.4%) in the control and CRT arms, respectively, and grade 4 toxicity was 0% and 4.7% (two of 43; 80% CI, 1.2% to 11.9%), respectively. In the CRT arm, three patients experienced grade 3-related late toxicity. Median DFS was 12 months in the CRT arm and 11 months in the control arm. Median OS was 24 months in both arms. First local recurrence was less frequent in the CRT arm (11% v 24%).

CONCLUSION

Adjuvant gemcitabine-based CRT is feasible, well-tolerated, and not deleterious; adding this treatment to full-dose adjuvant gemcitabine after resection of pancreatic cancer should be evaluated in a phase III trial.

Estimating optimal dose of twice-weekly gemcitabine for concurrent chemoradiotherapy in unresectable pancreatic carcinoma: mature results of GEMRT-01 Phase I trial. Int J Radiat Oncol Biol Phys. 2010;77:1426-1432. [PMID: 20056351 DOI: 10.1016/j.ijrobp.2009.06.053]

PURPOSE

To accurately determine the maximal tolerated dose, feasibility, and antitumor activity of concurrent chemoradiotherapy including twice-weekly gemcitabine in patients with unresectable pancreatic adenocarcinoma.

METHODS AND MATERIALS

Eligible patients with histologically proven adenocarcinoma of the pancreas were included in this Phase I trial. Radiotherapy was delivered to a total dose of 50 Gy. Concurrent chemotherapy with twice-weekly gemcitabine was administered during the 5 weeks of radiotherapy, from an initial dose of 30 mg/m(2). The gemcitabine doses were escalated in 10-mg/m(2) increments in a three-plus-three design, until dose-limiting toxicities were observed.

RESULTS

A total of 35 patients were included in the trial. The feasibility of chemoradiotherapy was high, because all the patients received the planned total radiation dose, and 26 patients (74%) received > or = 70% of the planned chemotherapy dose. The mean total delivered dose of gemcitabine was 417 mg/m(2) (i.e., 77% of the prescribed dose). The maximal tolerated dose of twice-weekly gemcitabine was 70 mg/m(2). Of the 35 patients, 13 had a partial response (37%) and 21 had stable disease (60%). Overall, the median survival and the 6-, 12-, and 18-month survival rates were 10.6 months and 82%, 31%, and 11%, respectively. Survival was significantly longer in patients with an initial performance status of 0 or 1 (p = .004).

CONCLUSION

Our mature data have indicated that gemcitabine doses can be increased < or = 70 mg/m(2), when delivered twice-weekly with concurrent radiotherapy. This combination shows promises to achieve better recurrence-free and overall survival. These results will serve as a basis for further implementation of the multimodal treatment of locally advanced pancreatic carcinoma.

Pretargeted radioimmunotherapy of pancreatic cancer xenografts: TF10-90Y-IMP-288 alone and combined with gemcitabine

Pancreatic cancer is a silent disease that most commonly presents in an already metastatic form. Current treatment options provide little survival benefit. Radiolabeled PAM4 IgG, a monoclonal antibody that recognizes a unique epitope associated with a mucin found almost exclusively in pancreatic cancer, has shown encouraging therapeutic effects in animal models and in early clinical testing ((90)Y-humanized PAM4 IgG, (90)Y-clivatuzumab tetraxetan). The studies reported herein examine a new pretargeting procedure for delivering therapeutic radionuclides.

METHODS

We prepared a humanized, recombinant tri-Fab bispecific monoclonal antibody (bsmAb) (TF10) using specificity for targeting pancreatic cancer of PAM4 and another Fab binding to a hapten (histamine-succinyl-glycine [HSG]) and tested this in a pretargeting setting with a (90)Y-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-di-HSG-peptide (pretargeted radioimmunotherapy [PT-RAIT]). Nude mice bearing established Capan-1 human pancreatic cancer xenografts were given TF10 and then received the (90)Y peptide as a single bolus dose 19 h later, or the therapy cycle was fractionated weekly. Other studies examined different combinations with gemcitabine.

RESULTS

PT-RAIT of 18.5 MBq ( approximately 50% of its maximum tolerated dose [MTD]) was as effective as the MTD of (90)Y-PAM4 IgG (5.55 MBq). Three monthly doses of 9.25 MBq of PT-RAIT combined with a monthly cycle of gemcitabine (3 weekly, 6-mg doses) significantly enhanced survival, compared with PT-RAIT alone. Adding gemcitabine as a radiosensitizer to 9.25 MBq of PT-RAIT enhanced objective responses. Weekly fractionation of the PT-RAIT, as compared with a single treatment, improved responses.

CONCLUSION

PAM4-based PT-RAIT with (90)Y hapten peptide is an effective treatment for pancreatic cancer, with less toxicity than (90)Y-PAM4 IgG, in this model. Combinations with gemcitabine and dose fractionation of the PT-RAIT enhanced therapeutic responses.

High frequency of radiation pneumonitis in patients with locally advanced non-small cell lung cancer treated with concurrent radiotherapy and gemcitabine after induction with gemcitabine and carboplatin

INTRODUCTION

The combination of chemotherapy and thoracic radiation is the standard treatment for locally advanced non-small cell lung cancer (NSCLC). However, most favorable chemotherapy regimen, timing of full-dose chemotherapy, and optimal combination of chemotherapy with radiation remain to be determined. Our primary objective was to evaluate the efficacy and safety of gemcitabine concurrent with radiotherapy after induction chemotherapy with gemcitabine plus carboplatin for locally advanced NSCLC.

PATIENTS AND METHODS

Patients with histologically proven NSCLC stage IIIA and -B received carboplatin (area under the curve of 2.5) and gemcitabine (800 mg/m) on days 1 and 8, every 21 days for two cycles, followed by conventional fractioned thoracic radiotherapy and concomitant weekly gemcitabine 200 mg/m, and finally, consolidation chemotherapy.

RESULTS

Inclusion was discontinued because of high-grade 3 to 5 radiation-pneumonitis events (6 of 19 patients, 31.6%), including one treatment-related death associated with radiation pneumonitis. Median follow-up was 11.9 months. Most common grades 3/4 hematological side effects comprised anemia, neutropenia 3 of 19 patients, each (15.8%), and thrombocytopenia (4 of 19, 21.1%) during induction. Partial response was observed in 10 patients (52.6%) following induction chemotherapy. After concurrent chemo-radiotherapy, overall response was 68.4%. Four patients (21.1%) underwent surgical resection. Median progression-free survival and overall survival were 12 +/- 1 month (95% confidence interval [CI], 9.8-14.1) and 21 +/- 3.5 months (95% CI, 14-27.9 months), respectively.

CONCLUSION

Concurrent radiotherapy with gemcitabine after induction with gemcitabine and carboplatin showed a high-response rate; however, it is associated with excessive pulmonary toxicity. Adjustments in gemcitabine dosage during radiotherapy or changes in radiotherapy planning could reduce toxicity.

APOMAB, a La-specific monoclonal antibody, detects the apoptotic tumor response to life-prolonging and DNA-damaging chemotherapy

Background

Antineoplastic therapy may impair the survival of malignant cells to produce cell death. Consequently, direct measurement of tumor cell death in vivo is a highly desirable component of therapy response monitoring. We have previously shown that APOMAB® representing the DAB4 clone of a La/SSB-specific murine monoclonal autoantibody is a malignant cell-death ligand, which accumulates preferentially in tumors in an antigen-specific and dose-dependent manner after DNA-damaging chemotherapy. Here, we aim to image tumor uptake of APOMAB® (DAB4) and to define its biological correlates.

Methodology/Principal Findings

Brisk tumor cell apoptosis is induced in the syngeneic EL4 lymphoma model after treatment of tumor-bearing mice with DNA-damaging cyclophosphamide/etoposide chemotherapy. Tumor and normal organ accumulation of Indium 111 (¹¹¹In)-labeled La-specific DAB4 mAb as whole IgG or IgG fragments was quantified by whole-body static imaging and organ assay in tumor-bearing mice. Immunohistochemical measurements of tumor caspase-3 activation and PARP-1 cleavage, which are indicators of early and late apoptosis, respectively, were correlated with tumor accumulation of DAB4. Increased tumor accumulation of DAB4 was associated directly with both the extent of chemotherapy-induced tumor cell death and DAB4 binding per dead tumor cell. Tumor DAB4 accumulation correlated with cumulative caspase-3 activation and PARP-1 cleavage as tumor biomarkers of apoptosis and was directly related to the extended median survival time of tumor-bearing mice.

Conclusions/Significance

Radiolabeled La-specific monoclonal antibody, DAB4, detected dead tumor cells after chemotherapy, rather than chemosensitive normal tissues of gut and bone marrow. DAB4 identified late apoptotic tumor cells in vivo. Hence, radiolabeled DAB4 may usefully image responses to human carcinoma therapy because DAB4 would capture the protracted cell death of carcinoma. We believe that the ability of radiolabeled DAB4 to rapidly assess the apoptotic tumor response and, consequently, to potentially predict extended survival justifies its future clinical development as a radioimmunoscintigraphic agent.

This article is part I of a two-part series providing proof-of-concept for the the diagnostic and therapeutic use of a La-specific monoclonal antibody, the DAB4 clone of which is represented by the registered trademark, APOMAB®.

The role of amifostine on late normal tissue damage induced by pelvic radiotherapy with concomitant gemcitabine: an in vivo study

In this in vivo study, we aimed to assess the radioprotective effect of amifostine on late normal tissue damage induced by gemcitabine concomitant with pelvic radiotherapy by histopathological and quantitative methods. Fifty-six male Wistar albino rats were randomly divided into seven experimental groups as follows: (I) gemcitabine, (II) radiation + gemcitabine, (III) radiation + gemcitabine + amifostine, (IV) radiation + amifostine, (V) sham radiation, (VI) amifostine, (VII) radiation. Irradiation was given to pelvic region with a dose of 25 Gy in 5 fractions. Amifostine was given for 30 min; gemcitabine was administered 24 h before the first fraction of radiotherapy. All animals were killed at the end of 4th month. Pathological examination was performed and the tissue collagen content was measured in bladder and rectal tissues. Fifty-one animals that were alive at the end of the follow-up period were analyzed. Thirty-five animals (68.6%) revealed grades I-III late effect in histopathological examination. We observed grade III colitis in 1 animal (radiation + gemcitabine) and bladder fibrosis in 4 animals (radiation and radiation + gemcitabine groups). There was no significant difference between any groups for bladder cystitis and fibrosis by Kruskal-Wallis method. Colitis was seen significantly lower in the radiation + gemcitabine + amifostine group (P = 0.0005). The collagen contents in the bladder and rectum of radiation and radiation + gemcitabine groups were markedly increased as compared to the sham group. This effect was reversed in the groups which received amifostine in addition to radiation and radiation + gemcitabine groups, but this difference was not significant. This study demonstrated that amifostine may have a beneficial effect in limiting rectal colitis from the radiosensitizing effect of gemcitabine.

A phase I radiation dose-escalation study to determine the maximal dose of radiotherapy in combination with weekly gemcitabine in patients with locally advanced pancreatic adenocarcinoma

Background

The primary objective of this study was to determine the maximum tolerated dose (MTD) of escalating doses of radiotherapy (RT) concomitantly with a fixed dose of gemcitabine (300 mg/m²/week) within the same overall treatment time.

Methods

Thirteen patients were included. Gemcitabine 300 mg/m²/week was administered prior to RT. The initial dose of RT was 45 Gy in 1.8 Gy fractions, escalated by adding 5 fractions of 1.8 Gy (one/week) to a dose of 54 Gy with a total duration kept at 5 weeks. All patients received a dynamic MRI to assess the pancreatic respiratory related movements. Toxicity was scored using the RTOG-EORTC toxicity criteria.

Results

Three of six patients experienced an acute dose limiting toxicity (DLT) at the 54 Gy dose level. For these patients a grade III gastro-intestinal toxicity (GI) was noted. Patients treated at the 45 Gy dose level tolerated therapy without DLT. The 54 Gy dose level was designated as the MTD and was deemed not suitable for further investigation.

Between both dose levels, there was a significant difference in percentage weight loss (p = 0.006) and also in cumulative GI toxicity (p = 0.027). There was no grade 3 toxicity in the 45 Gy cohort versus 4 grade 3 toxicity events in the 54 Gy cohort. The mean dose to the duodenum was significantly higher in the 54 Gy cohort (38.45 Gy vs. 51.82 Gy; p = 0.001).

Conclusion

Accelerated dose escalation to a total dose of 54 Gy with 300 mg/m²/week gemcitabine was not feasible. GI toxicity was the DLT. Retrospectively, the dose escalation of 9 Gy by accelerated radiotherapy might have been to large. A dose of 45 Gy is recommended. Considering the good patient outcomes, there might be a role for the investigation of a fixed dose of gemcitabine and concurrent RT with small fractions (1.8 Gy/day) in borderline resectable or unresectable non-metastatic locally advanced pancreatic cancer.

The multidisciplinary management of gastrointestinal cancer. Pancreatic cancer: from pathogenesis to cure

Pancreatic cancer is the fourth leading cause of cancer-related death in the USA. The disease has a high mortality rate and the 5-year survival rate is estimated to be 4%. Currently, surgical resection is only possible in 20% of patients; even then, the overall 5-year survival rate is only 25%. As such, surgical therapy alone is not sufficient for pancreatic carcinoma, and prospective investigation of additional modalities is crucial. Numerous negative trials have shown that chemotherapy alone is the standard of care after resection of pancreatic carcinoma. However, results remain poor and progress with new drugs is needed in this setting. For locally advanced disease, the situation is more complicated; the ideal chemoradiation schedule has not been clearly defined, and improvements could come in the near future from the use of new radiotherapy tools and targeted therapies. For advanced disease, chemotherapy alone has given very disappointing results. A multidisciplinary approach combining biological assessment of targets with clinical trials to evaluate new targeted drugs should be considered.

Clofarabine acts as radiosensitizer in vitro and in vivo by interfering with DNA damage response

PURPOSE

Combination treatment with radiotherapy and chemotherapy has emerged as the dominant form of cancer adjuvant regimens in recent years. Clofarabine, a newly approved drug for pediatric leukemia, is a second-generation purine nucleoside analogue that can block DNA synthesis and inhibit DNA repair. Therefore, we hypothesized that clofarabine could work synergistically with radiotherapy to increase the tumor cell response.

METHODS AND MATERIALS

The effects of clofarabine on radiosensitivity have been established in several tumor cell lines in vitro and in vivo using colony-forming assays and tumor xenografts. The effect of clofarabine on the DNA damage response was also studied in vitro by measuring gamma-H2AX focus formation.

RESULTS

Clonogenic survival was significantly reduced in irradiated cells treated with clofarabine, demonstrating the strong radiosensitizing effect of clofarabine. Furthermore, clofarabine displayed a radiosensitizing effect that was greater than gemcitabine or 5-fluorouracil. We also found that low doses of clofarabine can prolong the presence of radiation-induced gamma-H2AX nuclear focus formation, and high doses of clofarabine can induce DNA double-strand breaks, suggesting that clofarabine can interfere with DNA damage response pathways. In addition, clofarabine-induced radiosensitization was also established in vivo using a colorectal cancer model, DLD-1, in athymic nude mice. When combined with fractionated radiotherapy, a moderate dose of clofarabine led to a significant increase in tumor growth inhibition.

CONCLUSION

Clofarabine acts as a powerful radiosensitizer both in vitro and in vivo by interfering with the DNA damage response.

Treatment combining X-irradiation and a ribonucleoside anticancer drug, TAS106, effectively suppresses the growth of tumor cells transplanted in mice

PURPOSE

To examine the in vivo antitumor efficacy of X-irradiation combined with administration of a ribonucleoside anticancer drug, 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl)cytosine (TAS106, ECyd), to tumor cell-transplanted mice.

METHODS AND MATERIALS

Colon26 murine rectum adenocarcinoma cells and MKN45 human gastric adenocarcinoma cells were inoculated into the footpad in BALB/c mice and severe combined immunodeficient mice, respectively. They were treated with a relatively low dose of X-irradiation (2 Gy) and low amounts of TAS106 (0.1 mg/kg and 0.5 mg/kg). The tumor growth was monitored by measuring the tumor volume from Day 5 to Day 16 for Colon26 and from Day 7 to Day 20 for MKN45. Histologic analyses for proliferative and apoptotic cells in the tumors were performed using Ki-67 immunohistochemical and terminal deoxynucleotidyl transferase-mediated nick end labeling staining. The expression of survivin, a key molecule related to tumor survival, was assessed by quantitative polymerase chain reaction and immunohistochemical analysis.

RESULTS

When X-irradiation and TAS106 treatment were combined, significant inhibition of tumor growth was observed in both types of tumors compared with mice treated with X-irradiation or TAS106 alone. Marked inhibition of tumor growth was observed in half of the mice that received the combined treatment three times at 2-day intervals. Parallel to these phenomena, the suppression of survivin expression and appearance of Ki-67-negative and apoptotic cells were observed.

CONCLUSIONS

X-irradiation and TAS106 effectively suppress tumor growth in mice. The inhibition of survivin expression by TAS106 is thought to mainly contribute to the suppression of the tumor growth.

Gemcitabine and radiation therapy in non-small cell lung cancer: state of the art

Stage III non-small cell lung cancer (NSCLC) treatment is evolving. There are several choices available regarding which chemotherapy to use and how to optimally combine them with radiotherapy. Gemcitabine (Gemzar, Eli Lilly and Company, Indianapolis, USA) is a chemotherapeutic agent with activity in NSCLC, and preclinical studies have shown that gemcitabine is a potent radiosensitizer. These two characteristics make gemcitabine a potential option when treating patients with stage III NSCLC. This review article describes the efficacy and tolerance of gemcitabine when combined with radiation in those patients. Gemcitabine used concurrently with radiation, as an induction regimen before radiation, and as a consolidation regimen after radiation is reviewed.

Gemcitabine and cisplatin in a concomitant alternating chemoradiotherapy program for locally advanced head-and-neck cancer: a pharmacology-guided schedule

PURPOSE

Administration of gemcitabine together with cisplatin at cytotoxic doses in a chemoradiotherapy regimen is hampered by a high degree of local toxicity. Using the pharmacologic properties of the drug we designed a modified schedule aimed at reducing toxicity while preserving activity.

METHODS AND MATERIALS

Patients with squamous cell carcinomas of the oral cavity, pharynx and larynx, bulky T4, and/or N2 to N3 were eligible. Gemcitabine was administered at a dose of 800 mg/m2 on Days 1 and 12 and cisplatin at a dose of 20 mg/m2 on Days 2 to 5, every 21 days for 3 courses. Radiotherapy, delivered with standard fractionation, was given on Days 8 to 12 and 15 to 19 and was repeated 3 times up to a total dose of > or = 60 Gy.

RESULTS

A total of 28 patients were selected. Grade 3 to 4 stomatitis was recorded in 25 patients (89%). Thirteen patients (46%) experienced Grade 3 to 4 neutropenia. Febrile neutropenia occurred in 8 patients (29%) and in 2 was complicated by infection and death. The overall complete response rate was 79%. At a median follow up of 71 months, 11 patients had a locoregional relapse (3-year locoregional control, 64%); 6 patients had distant metastases, among whom only 2 were without locoregional recurrence. The 3-year progression-free survival is 39% and 3-year overall survival has been 43%.

CONCLUSION

The schedule modification did not attenuate local toxicity. Moreover, infections and especially pneumonia, were a major problem. The high activity of gemcitabine when combined with radiotherapy would most likely be better exploited in the context of modified radiation schemes.

Adjuvant gemcitabine and concurrent radiation for patients with resected pancreatic cancer: a phase II study

The safety and efficacy of gemcitabine and concurrent radiation to the upper abdomen followed by weekly gemcitabine in patients with resected pancreatic cancer was determined. Patients with resected adenocarcinoma of the pancreas were treated with intravenous gemcitabine administered twice-weekly (40 mg m⁻²) for 5 weeks concurrent with upper abdominal radiation (50.4 Gy in 5½ weeks). At the completion of the chemoradiation, patients without disease progression were given gemcitabine (1000 mg m⁻²) weekly for two cycles. Each cycle consisted of 3 weeks of treatment followed by 1 week without treatment. Forty-seven patients were entered, 46 of whom are included in this analysis. Characteristics: median age 61 years (range 35–79); 24 females (58%); 73% stage T3/T4; and 70% lymph node positive. Grade III/IV gastrointestinal or haematologic toxicities were infrequent. The median survival was 18.3 months, while the median time to disease recurrence was 10.3 months. Twenty-four percent of patients were alive at 3 years. Only six of 34 patients with progression experienced local regional relapse as a component of the first site of failure. These results confirm the feasibility of delivering adjuvant concurrent gemcitabine and radiation to the upper abdomen. This strategy produced good local regional tumour control.

The relation between deoxycytidine kinase activity and the radiosensitising effect of gemcitabine in eight different human tumour cell lines

Background

Gemcitabine (dFdC) is an active antitumour agent with radiosensitising properties, shown both in preclinical and clinical studies. In the present study, the relation between deoxycytidine kinase (dCK) activity and the radiosensitising effect of gemcitabine was investigated in eight different human tumour cell lines.

Methods

Tumour cells were treated with dFdC (0–100 nM) for 24 h prior to radiotherapy (RT) (γ-Co⁶⁰, 0–6 Gy, room temperature). Cell survival was determined 7, 8, or 9 days after RT by the sulforhodamine B test. dCK activity of the cells was determined by an enzyme activity assay.

Results

A clear concentration-dependent radiosensitising effect of dFdC was observed in all cell lines. The degree of radiosensitisation was also cell line dependent and seemed to correlate with the sensitivity of the cell line to the cytotoxic effect of dFdC. The dCK activity of our cell lines varied considerably and differed up to three fold from 5 to 15 pmol/h/mg protein between the tested cell lines. In this range dCK activity was only weakly related to radiosensitisation (correlation coefficient 0.62, p = 0.11).

Conclusion

Gemcitabine needs to be metabolised to the active nucleotide in order to radiosensitise the cells. Since dFdCTP accumulation and incorporation into DNA are concentration dependent, the degree of radiosensitisation seems to be related to the extent of dFdCTP incorporated into DNA required to inhibit DNA repair. The activity of dCK does not seem to be the most important factor, but is clearly a major factor. Other partners of the intracellular metabolism of gemcitabine in relation to the cell cycle effects and DNA repair could be more responsible for the radiosensitising effect than dCK activity.

Gemcitabine radiosensitization after high-dose samarium for osteoblastic osteosarcoma

Osteoblastic metastases and osteosarcoma can avidly concentrate bone-seeking radiopharmaceuticals. We sought to increase effectiveness of high-dose (153)Samarium ethylenediaminetetramethylenephosphonate (153Sm-EDTMP, Quadramet) on osteosarcomas using a radiosensitizer, gemcitabine. Fourteen patients with osteoblastic lesions were treated with 30 mCi/kg 153Sm-EDTMP. Gemcitabine was administered 1 day after samarium infusion. Residual total body radioactivity was within the safe range of <3.6 mCi on day +14 (1.1 +/- 0.4 mCi; range, 0.67-1.8 mCi). All patients received autologous stem cell reinfusion 2 weeks after 153Sm to correct expected grade 4 hematopoietic toxicity. Peripheral blood progenitor cells were infused in 11 patients; three patients had marrow infused. Blood count recovery was uneventful after peripheral blood progenitor cells in 11 of 11 patients. Toxicity from a single infusion of gemcitabine (1,500 mg/m2) in combination with 153Sm-EDTMP was minimal (pancytopenia). However, toxicity from a daily gemcitabine regimen (250 mg/m2/d x 4-5 days) was excessive (grade 3 mucositis) in one of two patients. There were no reported episodes of hemorrhagic cystitis (hematuria) or nephrotoxicity. At the 6- to 8-week follow-up, there were six partial remissions, two mixed responses, and six patients with progressive disease. In the 12 patients followed >1 year, there have been no durable responses. Thus, although high-dose 153Sm-EDTMP + gemcitabine has moderate palliative activity (improved pain; radiologic responses) in this poor-risk population, additional measures of local and systemic control are required for durable control of relapsed osteosarcoma with osteoblastic lesions. The strategy of radioactive drug binding to a target followed by a radiosensitizer may provide synergy and improved response rate.

Staging of pancreatic cancer with multidetector CT in the setting of preoperative chemoradiation therapy

BACKGROUND

Preoperative chemoradiation can potentially improve outcomes in patients with pancreatic cancer. This study addresses its effect on staging pancreatic cancer with multidetector computed tomography (MDCT).

METHODS

Fifty-five patients underwent a dual-phase MDCT pancreas protocol for proved pancreatic cancer. Of these, 16 patients underwent preoperative chemoradiation. Three radiologists independently reviewed images to assess for locally advanced disease, liver and peritoneal metastases on baseline studies of all 55 patients, and on follow-up preoperative studies for the 16 patients receiving preoperative therapy. Overall score for resectability was graded on a scale from 1 to 5 (1, definitely resectable; 5. definitely unresectable). Receiver operating characteristic curves and weighted (kappa statistics were determined.

RESULTS

The areas under the receiver operating characteristic curves for readers 1, 2, and 3 were 0.98, 0.96, and 0.90, respectively. Weighted kappa values for reader 1 versus reader 2, reader 1 versus reader 3, and reader 2 versus reader 3 were 0.90, 0.57, and 0.54, respectively. Interpreting scores of 1 to 3 for resectability as resectable disease, the mean values for sensitivity, specificity, negative predictive value, positive predictive value, and accuracy were 0.92, 0.91, 0.74, 0.98, and 0.92 respectively.

CONCLUSION

The negative predictive value for MDCT for identifying unresectable pancreatic cancer in the setting of preoperative therapy is comparable to that reported in the absence of neoadjuvant therapy.

Chemoradiotherapy in gallbladder cancer

Gallbladder cancer (GC) is considered a rare disease associated with a poor prognosis. Unfortunately, the low number of cases makes the performance of trials addressing the role of adjuvant, neoadjuvant, and/or palliative therapy difficult. For a long time, the majority of trials were 5-fluorouracil (5 FU)-based, and results were uniformly poor. Since the introduction of Gemcitabine, response rates of approximately 30% have been observed through the use of this drug and new approaches have been tested. In this sense, drugs such as Cisplatin and Capecitabine have been employed concurrently with gemcitabine and/or radiation. Since a recurrence pattern is both distant and local, chernoradiation seems a logical option to deal with the disease. However, at the present time, the lack of valid and scientific evidence means that most of the recommendations originate from trials dealing with other tumors, such as pancreas cancer and biliary tract cancer (BTC). The aforementioned treatment alternatives warrant further evaluation focusing on GC.

Unraveling the mechanism of radiosensitization by gemcitabine: the role of TP53

Gemcitabine has excellent radiosensitizing properties, as shown in both preclinical and clinical studies. Radiosensitization correlated with the early S-phase block of gemcitabine. In the present study, we investigated the role of TP53 in the radiosensitizing effect of gemcitabine. Isogenic A549 cells differing in TP53 status were treated with gemcitabine during the 24 h prior to irradiation. Cell survival was determined 7 days after irradiation by the sulforhodamine B test. In addition, cell cycle perturbation was determined by flow cytometry and TP53 expression by Western blot analysis. Gemcitabine caused a concentration-dependent radiosensitizing effect in all cell lines. Transformed A549 cells were less sensitive to the cytotoxic effect of gemcitabine. The cell cycle arrest early in the S phase was dependent on the drug dose but was comparable in the different cell lines and was not related to functional TP53. Using isogenic cell lines, we have shown that neither TP53 status nor the transfection procedure influenced the radiosensitizing effect of gemcitabine. Since both the radiosensitizing effect at equitoxic concentrations and the cell cycle effect of gemcitabine were independent of TP53 expression, it is likely that TP53 protein does not play a crucial role in the radiosensitizing mechanism of gemcitabine.

The radiosensitising effect of difluorodeoxyuridine, a metabolite of gemcitabine, in vitro

PURPOSE

Gemcitabine is an active antitumour agent with radiosensitising properties. Gemcitabine is rapidly metabolised, intracellularly as well as extracellularly, by deoxycytidine deaminase to difluorodeoxyuridine (dFdU), a compound with little antitumour activity. However, plasma concentrations are maintained for a prolonged period (>24 h) at levels known to cause growth inhibition. This is the first study that investigates the radiosensitising potential of dFdU in vitro.

METHODS

ECV304 and H292, human cancer cells, were treated with different concentrations dFdU (0-100 microM) during 24 h before radiation treatment (RT). The schedule dependency of the radiosensitising effect was studied by varying the interval between dFdU and radiation treatment. In addition, the cell cycle effect of dFdU was investigated with flow cytometry, and the induction of apoptosis under radiosensitising conditions was determined by Annexin V staining and caspase 3 cleavage.

RESULTS

dFdU caused a clear concentration-dependent radiosensitising effect in both ECV304 and H292 cells. Dose enhancement factor (DEF) increased with an increasing concentration of dFdU: DEFs were 1.10, 1.60 and 2.17 after treatment with 10, 25 and 50 microM dFdU, respectively, in ECV304 cells and 1.08, 1.31 and 1.60 after treatment with 25, 50 and 100 microM, respectively, in H292 cells. DEFs decreased with an increasing interval of 0-24 h between dFdU treatment and radiation. Under radiosensitising conditions, the combination dFdU and radiation resulted in an increased induction of apoptosis. In addition, the cell cycle effect of dFdU, an arrest at the early S phase, is comparable with the cell cycle effect of gemcitabine.

CONCLUSIONS

dFdU, the main metabolite of gemcitabine, causes a concentration- and schedule- dependent radiosensitising effect in vitro. Since the metabolite is present in plasma for a long period (>24 h) after treatment with gemcitabine, it might be partly responsible for the interaction between radiotherapy and gemcitabine. This observation might have important consequences for the optimal schedules of the combination gemcitabine and radiation therapy.

A phase II study of alternating cycles of split course radiation therapy and gemcitabine chemotherapy for inoperable pancreatic or biliary tract carcinoma

Because of increased toxicity, full doses of gemcitabine and radiation therapy cannot routinely be given concurrently. The purpose of the present study was to determine the toxicity and response to treatment with full-dose gemcitabine given between cycles of split-course radiation therapy (nonconcurrent treatment) for inoperable periampullary adenocarcinoma. Treatment consisted of 3 6 week courses for a total of 18 weeks: 1000 mg/m gemcitabine intravenous bolus once a week x 2 weeks; 1 week break; 2 weeks of radiation therapy (1.8 Gy per fraction); 1 week break x 3. The total dose of radiation consisted of 45 Gy to the tumor + regional nodes followed by a 5.4-Gy boost. Patients were restaged at week 15 and at the completion of all treatment. Patients underwent resection if there was sufficient response. A total of 42 patients (40 pancreatic, 1 gallbladder, 1 biliary tract) were enrolled between March 1999 and July 2002. All but 2 medically inoperable patients had evidence of major vessel involvement. Median age was 63 years (range, 40-80 years). All patients were evaluable for response. There were 10 objective partial responses (24%). Six responders underwent resection with a mean survival of 18 months. Mean survival for all 42 patients was 10.3 months (range, 2.0-32.5 months; median, 9.5 months). Four patients experienced grade 3 or 4 gastrointestinal toxicity. Alternating cycles of split-course radiotherapy and gemcitabine chemotherapy permits the delivery of full doses of both modalities with acceptable tolerance. Despite the prolongation in radiation treatment time because of split-course treatment, patients with sufficient response were able to undergo resection.

Mismatch repair proficiency is not required for radioenhancement by gemcitabine

PURPOSE

Mismatch repair (MMR) proficiency has been reported to either increase or decrease radioenhancement by 24-h incubations with gemcitabine. This study aimed to establish the importance of MMR for radioenhancement by gemcitabine after short-exposure, high-dose treatment and long-exposure, low-dose treatment.

METHODS AND MATERIALS

Survival of MMR-deficient HCT116 and MMR-proficient HCT116 + 3 cells was analyzed by clonogenic assays. Mild, equitoxic gemcitabine treatments (4 h, 0.1 microM vs. 24 h, 6 nM) were combined with gamma-irradiation to determine the radioenhancement with or without recovery. Gemcitabine metabolism and cell-cycle effects were evaluated by high-performance liquid chromatography analysis and bivariate flow cytometry.

RESULTS

Radioenhancement after 4 h of 0.1 microM of gemcitabine was similar in both cell lines, but the radioenhancement after 24 h of 6 nM of gemcitabine was reduced in MMR-proficient cells. No significant differences between both cell lines were observed in the gemcitabine metabolism or cell-cycle effects after these treatments. Gemcitabine radioenhancement after recovery was also lower in MMR-proficient cells than in MMR-deficient cells.

CONCLUSION

Mismatch repair proficiency decreases radioenhancement by long incubations of gemcitabine but does not affect radioenhancement by short exposures to a clinically relevant gemcitabine dose. Our data suggest that MMR contributes to the recovery from gemcitabine treatment.

Adjuvant gemcitabine and concurrent continuous radiation (45 Gy) for resected pancreatic head carcinoma: a multicenter Belgian Phase II study

PURPOSE

To evaluate the feasibility and tolerance of a postoperative course of gemcitabine (GEM) combined with continuous radiation after curative resection of pancreatic adenocarcinoma.

METHODS AND MATERIALS

Thirty patients (median age, 61 years; performance status, 0 to 1) with Stage II and III curatively resected pancreatic head adenocarcinoma were included. Gemcitabine 1000 mg/m2 (3 out of 4 weeks, two cycles) was given within 8 weeks of surgery and followed by GEM 300 mg/m2 weekly combined with continuous radiation (45 Gy in 25 fractions, 1.8 Gy per fraction).

RESULTS

For GEM alone, all patients received the two courses with dose reductions in 14 of 30 patients (46%). All but 3 patients completed full chemoradiation; 1 stopped radiation because of subocclusion of a gastroenterostomy, and 2 did not start owing to disease progression. Reduction in GEM during radiation was necessary in 12 of 30 patients (40%). No toxic death was noted; World Health Organization Grade 3/4 hematologic and nonhematologic toxicities were seen in 10 of 30 patients (33%) and 3 of 30 patients (10%), respectively. After a median follow-up of 19 months, no late toxicity was reported. Eleven patients died from progressive disease; median disease-free survival and overall survival were 14.5 and 19 months, respectively.

CONCLUSION

This adjuvant combination is well tolerated and can be safely administered after curative surgery for pancreatic cancer. Further evaluation of this regimen is ongoing.

Emerging drugs in pancreatic cancer

Improving survival in patients with pancreatic cancer remains a formidable challenge. For the few patients with localised stages of the disease, intra-operative radiotherapy, adjuvant chemoradiotherapy and neo-adjuvant therapies remain non-validated and the survival benefit conferred by 5-fluorouracil-folinic acid adjuvant chemotherapy over radical surgery alone is still a matter of debate. Gemcitabine has recently emerged as the standard single agent in advanced stages of the disease and pharmacokinetic refinements such as the use of a fixed-dose infusion rate may further improve still rather modest result figures. At present, most efforts deal with the development of more effective doublet or triplet therapies, combining gemcitabine with either conventional cytotoxic drugs--the most promising being oxaliplatin--or more innovative, targeted therapeutic agents. Among these agents, matrix metalloprotease inhibitors and farnesyltransferase inhibitors have already undergone Phase III trials, alone or in combination with gemcitabine, with rather disappointing results. However, preclinical and Phase I and II studies of cyclooxygenase-2 or lipoxygenase inhibitors, various immunotherapeutic approaches and several tyrosine kinase inhibitors or monoclonal antibodies against growth factors or their receptors are encouraging and may provide some hope for patients with pancreatic cancer.

Phase I study of conformal radiotherapy with concurrent gemcitabine in locally advanced bladder cancer

PURPOSE

A prospective phase I trial was conducted to determine the maximal tolerated dose of gemcitabine given once weekly during hypofractionated conformal radiotherapy to patients with locally advanced transitional cell carcinoma of the bladder. Eight male patients, median age 69 years, with Stage T2 (n = 4) or T3 (n = 4) N0M0, were enrolled in cohorts of 3. Treatment comprised conformal radiotherapy (52.5 Gy in 20 fractions) within 4 weeks, with concurrent gemcitabine once weekly for four cycles. The weekly gemcitabine dose was escalated from 100 mg/m(2) in increments of 50 mg/m(2) per cohort. Dose-limiting toxicity was defined as any acute Radiation Therapy Oncology Group (RTOG) toxicity Grade 3 or greater arising in >1 of 3 patients in each cohort. Tumor response was assessed cystoscopically and radiologically at 3 months.

RESULTS

All 8 patients completed radiotherapy, and 6 of 8 completed chemoradiotherapy. No acute toxicity greater than RTOG Grade 1 was seen with gemcitabine at 100 mg/m(2). Dose-limiting toxicity was observed at 150 mg/m(2) with Grade 3 toxicity seen in 2 of 2 patients (one bladder, one bowel). An additional 3 patients received 100 mg/m(2) with minimal toxicity. No hematologic toxicity was encountered. A complete response was seen in 7 (87.5%) of 8 patients, all of whom were disease free at a median follow-up of 19.5 months (range, 14-23 months). No late toxicity (greater than RTOG Grade 0) has been observed.

CONCLUSION

The maximal tolerated dose for gemcitabine given once weekly with concurrent hypofractionated conformal bladder radiotherapy was 150 mg/m(2), with a maximal recommended dose of 100 mg/m(2). This dose regimen has now entered Phase II clinical trials.

Combined Modality Therapy of Gemcitabine and Radiation

The combination of gemcitabine and radiotherapy is a promising combined modality therapy. However, the clinical application of this combination has to be implemented carefully because of an increased toxicity to normal tissues. A body of experimental evidence shows that gemcitabine is a potent radiosensitizer in vitro and in vivo. The observations so far indicate that various mechanisms are responsible for the radiosensitizing effect. Although it is often difficult to transfer experimental data to the clinic, these studies offer the possibility to develop an improved schedule of administration for patient treatment, based on rational evidence in tumor biology. In the current review, the preclinical data that support the use of gemcitabine as a radiosensitizing agent and the clinical trials that have been conducted to date are summarized.

An evaluation of gemcitabines differential radiosensitising effect in related bladder cancer cell lines

The aim of this study was to establish the radiosensitising properties of gemcitabine in a pair of related bladder tumour cell lines with differential radiosensitivity. The radioresistant bladder tumour cell line MGH-U1 and its radiosensitive mutant clone, S40b (both p53 mutant), had SF₂ values (surviving fraction at 2 Gy) of 0.98 and 0.64, respectively (P<0.001). Colony-forming assays showed that at 0.01 μM gemcitabine radiosensitisation occurred only in the S40b cell line (dose-modifying factor (DMF)=1.4). At 0.3 μM (killing 50% of cells), both cell lines were radiosensitised; DMF=2.25 and 1.2 for MGH-U1 and S40b, respectively. These data suggest that gemcitabine is an effective radiosensitiser in bladder cancer cell lines, with greater sensitisation in the radioresistant parental line–a feature that should be useful in a clinical setting.

Cell cycle effect of gemcitabine and its role in the radiosensitizing mechanism in vitro

PURPOSE

The mechanism of radiosensitization by gemcitabine is still unclear. It has been hypothesized that the accumulation of cells in early S phase may play a role in enhancing radiosensitivity.

METHODS AND MATERIALS

The schedule dependency of the radiosensitizing effect was studied in ECV304, human bladder cancer cells, and H292, human lung cancer cells, by varying the incubation time and time interval between gemcitabine and radiation treatment. To determine the role of cell cycle perturbations in the radiosensitization, the influence of gemcitabine on the cell cycle at the moment of radiation was investigated by flow cytometry.

RESULTS

The radiosensitizing effect increased with a longer incubation period: Dose enhancement factors varied from 1.30 to 2.82 in ECV304 and from 1.04 to 1.78 in H292 after treatment during 8-32 h, respectively. Radiosensitization decreased with an increasing interval: Dose enhancement factors varied from 2.26 to 1.49 in ECV304 and from 1.45 to 1.11 in H292 after an interval 0-24 h, respectively. Cells were blocked in the early S phase of the cell cycle by gemcitabine. The highest percentage S-phase cells was observed after treatment with the schedules that resulted in the highest radiosensitizing effect.

CONCLUSIONS

We observed a clear schedule-dependent radiosensitization by gemcitabine. Our findings demonstrated a correlation between gemcitabine-induced early S-phase block and the radiosensitizing effect.

Should patients with locally advanced, non-metastatic carcinoma of the pancreas be irradiated?

A small number of patients exist with carcinoma of the pancreas with an inoperable but not metastasized tumor. Prospective randomized studies defined the standard of combined radiochemotherapy during the early 1980s for these patients. Since then, new drugs have shown considerable activity and in parallel improvements in radiotherapy treatment planning and delivery have been achieved. Therefore, it is time to ask whether patients with locally advanced, inoperable pancreatic cancer without metastases should still be irradiated or not. This review summarizes the current literature on combined radiochemotherapy for locally advanced carcinoma of the pancreas. Median survival times of 10-11 months and 1-year survival rates of about 40% can be achieved with modern radiochemotherapy regimens.

Radiation therapy with once-weekly gemcitabine in pancreatic cancer: current status of clinical trials

Clinical trials investigating a variety of gemcitabine-based chemoradiation therapy regimens were initiated several years ago and remain under active investigation for the treatment of patients with pancreatic cancer. These trials are based, in part, on the activity of gemcitabine as a single agent in pancreatic cancer, preclinical studies that demonstrated radiosensitization, and the need for approaches with greater efficacy than that provided by 5-fluorouracil (5-FU)-based chemoradiation therapy. In this review, we describe and compare several Phase I clinical trials investigating dose escalation of once-weekly gemcitabine with concurrent radiation therapy. We also describe a relatively novel approach successfully investigating radiation dose escalation with a standard weekly dose of gemcitabine. Toxicity data from this trial, and the prior trials of gemcitabine dose escalation with more conventional radiation therapy, suggest that the volume of normal tissue radiated in gemcitabine-based chemotherapy regimens may be the most critical consideration for future trial designs. Finally, we highlight the need to fully consider the design of future trials in the context of both local and distant disease control, given the radiosensitizing potential and systemic activity of gemcitabine.

Initial experience combining cyclooxygenase-2 inhibition with chemoradiation for locally advanced pancreatic cancer

Pancreatic cancer is a lethal disease that is resistant to chemotherapy and radiotherapy. Gemcitabine has recently been shown to be an improvement over 5-fluorouracil in patients with advanced disease. It is also a potent radiosensitizer, which has led to the investigation of gemcitabine with concurrent radiotherapy. However, preliminary results indicate that there are significant limitations to this approach in this challenging disease. Pancreatic cancer cells have alterations in many molecular signaling pathways that may be responsible for their resistance to cytotoxic therapy and aggressive behavior. Cyclooxygenase-2 (COX-2) is commonly overexpressed in pancreatic tumors, and preclinical evidence indicates that selective COX-2 inhibition enhances both chemotherapy and radiotherapy response, without affecting normal tissue damage. We have initiated preclinical studies as well as a phase I clinical protocol evaluating the combination of gemcitabine and celecoxib (Celebrex) with radiotherapy. In preclinical studies, celecelecoxib strongly enhanced the antitumor efficacy of chemoradiation. However, preliminary observations from both the preclinical experiments as well as the clinical protocol have revealed more toxicity with this combination than with gemcitabine and radiotherapy alone. These observations require further study, but are cause for concern when combining gemcitabine, radiotherapy, and celecoxib.

A phase I-II study of weekly cisplatin and gemcitabine with concurrent radiotherapy in locally advanced cervical carcinoma

BACKGROUND

The purpose of this study was to determine the maximum-tolerated dose (MTD) and the antitumor activity of gemcitabine when administered in combination with concurrent cisplatin and radiotherapy in locally advanced cervical carcinoma (LACC).

PATIENTS AND METHODS

Patients with histologically confirmed LACC (International Federation of Gynecology and Obstetrics IIB-IVA), previously untreated, were eligible for entry in the study to receive radiotherapy and concomitant weekly chemotherapy with cisplatin 40 mg/m(2) and gemcitabine at increasing doses levels until the MTD was found.

RESULTS

Thirty-six patients were included. Sixteen patients were entered at four dose levels. The MTD was 150 mg/m(2) and the recommended dose of gemcitabine for phase II was 125 mg/m(2). Twenty additional patients were entered at this level. Toxicity at the recommended dose was acceptable with grade 3/4 toxicity in <20% of patients. Thirty-five of thirty-six patients (97.3%) achieved an objective response, 32 (88.8%) a complete response (CR) three a (8.3%) partial response and one (2.7%) stable disease. At a median follow-up of 26 months, 28 of 36 patients (77.7%) are in sustained complete remission and seven of 36 (19.4%) have relapsed. The 3-year disease-free and overall survival rates are 67% and 72%, respectively.

CONCLUSION

The association of cisplatin and gemcitabine with concurrent radiotherapy is active and well-tolerated in untreated LACC.

Multimodality therapy for head and neck cancer

The refinement of radiation therapy techniques should result in a decrease in morbidity in canine and feline nasal carcinoma patients and should further allow for the addition of adjuvant therapies. Patients with large oral tumors that are incompletely excised should have radiation therapy added to their treatment regimen. Tumors with significant metastatic potential, such as melanoma, should be considered for addition of chemotherapy. Carboplatin has activity in melanomas and is being added at several institutions, but trial results are not yet available. Chemoradiation has become the treatment of choice for human head and neck squamous cell carcinomas but remains largely unexplored in veterinary medicine. Hopefully, development of chemoradiation will benefit feline squamous cell carcinoma patients, because current treatment regimens are largely ineffective. Immunotherapy agents and targeted biologic therapeutics seem to hold promise for the future.