A Randomized Phase III Study of Arfolitixorin versus Leucovorin with 5-Fluorouracil, Oxaliplatin, and Bevacizumab for First-Line Treatment of Metastatic Colorectal Cancer: The AGENT Trial

PURPOSE

Suboptimal treatment outcomes with 5-fluorouracil (5-FU)/folate, the standard of care for metastatic colorectal cancer (mCRC), have generated interest in optimizing the folate. Arfolitixorin ([6R]-5,10-methylene-tetrahydrofolate) is an immediately active folate and may improve outcomes over the existing standard of care (leucovorin).

EXPERIMENTAL DESIGN

AGENT was a randomized, phase III study (NCT03750786). Patients with mCRC were randomized to arfolitixorin (120 mg/m2 given as two intravenous bolus doses of 60 mg/m2) or leucovorin (400 mg/m2 given as a single intravenous infusion) plus 5-FU, oxaliplatin, and bevacizumab. Assessments were performed every 8 weeks. The primary endpoint was the superiority of arfolitixorin for overall response rate (ORR).

RESULTS

Between February 2019 and April 2021, 490 patients were randomized (245 to each arm). After a median follow-up of 266 days, the primary endpoint of superiority for ORR was not achieved (48.2% for arfolitixorin vs. 49.4% for leucovorin, Psuperiority = 0.57). Outcomes were not achieved for median progression-free survival (PFS; 12.8 and 11.6 months, P = 0.38), median duration of response (12.2 and 12.9 months, P = 0.40), and median overall survival (23.8 and 28.0 months, P = 0.78). The proportion of patients with an adverse event of grade ≥3 severity was similar between arms (68.7% and 67.2%, respectively), as was quality of life. BRAF mutations and MTHFD2 expression were both associated with a lower PFS with arfolitixorin.

CONCLUSIONS

The study failed to demonstrate clinical benefit of arfolitixorin (120 mg/m2) over leucovorin. However, it provides some useful insights from the first-line treatment setting, including the effect of gene expression on outcomes.

SIGNIFICANCE

This phase III study compared arfolitixorin, a direct-acting folate, with leucovorin in FOLFOX plus bevacizumab in mCRC. Arfolitixorin (120 mg/m2) did not improve the ORR, potentially indicating a suboptimal dose.

Abstract 346: Tumoral expression of folate-associated genes is associated with progression-free survival of patients with advanced colorectal cancer

Background - 5-fluorouracil (5-FU) in combination with the folate leucovorin (LV) has formed the backbone of chemotherapy for advanced colorectal cancer for several decades. A number of genes encode proteins that participate in transportation of LV into the cells, as well as in subsequent metabolic action. We previously reported that high tumoral expression of genes involved in folate transport, polyglutamation, and metabolism was associated with decreased risk of recurrent disease in patients with stage III colorectal cancer treated with 5-FU + LV (FLV) alone, or in combination with oxaliplatin (FLOX) according to the Nordic bolus regimen. The aim of the present study was to determine the association between expression of the folate-associated genes ABCC3, MTHFD2, SLC19A1, SLC25A32, SLC46A1, and TYMS and outcome of patients with metastatic colorectal cancer subjected to palliative chemotherapy.

Patients and Methods - A total of 290 patients treated with FLV (n = 113), FLOX (n = 102) or FLV + irinotecan (FLIRI, n = 75) were included. Relative gene expression (ΔCt) was determined in primary tumors by quantitative PCR and analyzed in relation to clinical benefit, based on RECIST criteria and 3-year progression-free survival (PFS). Analyses were conducted on the whole study group, and on subgroups based on tumor stage at primary surgery (subgroup 1, stage I-III; subgroup 2, stage IV). An ANOVA test was used to assess the relationship between expression and clinical benefit. A multivariate Cox proportional hazard model was applied to assess potential associations between genetic markers, clinical variables and PFS. A Stepwise model selection was used to identify a minimal set of variables associated with PFS.

Results - Low expression of TYMS and MTHFD2, and high expression of ABCC3 was significantly associated with a clinical benefit in the whole group (p<0.0001, p=0.017, and p=0.028, respectively). The association between TYMS expression and clinical benefit was seen in both sub-groups, whereas ABCC3 expression was significant in subgroup 2 (p=0.041). Multivariate models showed that low TYMS and high SLC25A32 expression in subgroup 1 and high ABCC3 expression in subgroup 2 correlated significantly with better PFS (Hazard Ratio (HR) = 0.75 (95% CI = 0.57-1.0), HR = 2.21 (95% CI = 1.37-3.6), and HR = 1.34 (95% CI = 1.08 -1.7), respectively).

Conclusion - Expression of TYMS, the target enzyme of 5-FU, was strongly associated with clinical benefit in the whole group, whereas expression of TYMS and the folate transporters SLC25A32, and ABCC3 was associated with PFS in the subgroups (stage I-III and stage IV), respectively. The prospective global phase III study AGENT is presently conducted on patients with advanced colorectal cancer, to determine whether expression of these genes can predict response to 5-FU-based chemotherapy that includes LV or the novel folate arfolitixorin.

Citation Format: Yvonne Wettergren, Elisabeth Odin, Göran Carlsson, Pushpa Saksena, Anders Edsjö, Alessandro Di Cara, Roger Tell, Bengt Gustavsson. Tumoral expression of folate-associated genes is associated with progression-free survival of patients with advanced colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 346.

MYC as a candidate upstream controller involved in TYMS gene expression and 5-FU/folate treatment efficacy in colorectal cancer

e15512

Background: One of the target enzymes of 5-fluorouracil (5-FU)-based therapies is thymidylate synthase (TS) encoded by the TYMS gene. To enhance the effect of 5-FU, a folate analogue is often provided as part of the treatment. In this context, it has previously been shown in the ISO-CC-005 clinical study that TYMS gene expression can be predictive of response to 5-FU + folate analogue Arfolitixorin. Methods: To better understand the role of TYMS expression as a predictor of response to 5-FU + folate-based therapies and identify potential mechanisms and biomarkers of sensitivity/resistance, we leveraged data from the publicly available cancer genome atlas database (TCGA). We combined this information with a knowledgebase of causal biological relationships extracted from peer reviewed publications, to identify other relevant genes and candidate upstream controllers directly or indirectly related to TYMS expression and 5-FU + folate efficacy. Results: In TCGA subjects suffering from colorectal cancer (CRC) (stage IV tumors, treated with FOLFOX/FOLFIRI (n = 38)), lower TYMS expression was associated with a better overall survival (OS). This is consistent with what has been observed in the ISO-CC-005 study. Applying our causal biology knowledgebase to both genes identified as correlated to TYMS expression in TCGA CRC tumors and other published sets of genes associated with FOLFOX or FOLFIRI efficacy, we identified overlap with a MYCN signature. Notably MYC has been shown to directly activate TYMS expression. Thus, the MYC family is a compelling candidate upstream controller of these genes. We scored TCGA CRC tumors for inferred MYC activity, using this MYCN gene signature, and evaluated the inferred activity with respect to OS. In stage IV tumors, higher inferred MYC activity appears to be associated with worse OS. To further characterize this inferred MYC activity, we employed a transcriptomics-based cell deconvolution estimation of immune cell population proportions in the TCGA CRC cohort. We found inferred MYC activity inversely correlated with immune cell proportions overall, specifically strongest with those of pDCs and classical monocytes. Conclusions: MYC activation, a known transcriptional regulator of TYMS, has been identified as a potentially relevant common upstream controller of a group of genes involved in 5-FU + folate analogue efficacy. Here we have also observed a similar relationship to OS between TYMS and inferred MYC activity in Stage IV CRC. MYC family activity (and activated protein forms), genes of the MYCN signature, or the identified immune cell proportions are all potential biomarker candidates to explore as factors in 5-FU + folate analogue efficacy.

Folate pathway gene expression in metastatic colorectal cancer patients treated with arfolitixorin/5-FU-based chemotherapy

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Background: Arfolitixorin is the natural, biologically active form of the marketed folates and is expected to be efficacious in a larger proportion of patients with less inter- and intra-individual variability compared with e.g. leucovorin. We have previously found a positive correlation between survival and expression of folate pathway genes in stage III/IV CRC treated with 5-fluorouracil/leucovorin (5-FU/LV). Low expression of folate-related genes may lead to poor response to 5-FU/LV-based treatment, since suboptimal transport and metabolization of LV yield insufficient active [6R]-5,10-methylenetetrahydrofolate and weak inhibition of the target enzyme thymidylate synthase (TYMS). The aim of the present study was to investigate possible confounders and biomarkers of arfolitixorin/5-FU-based treatment in relation to safety and response in a phase I/IIa metastatic colorectal cancer (mCRC) trial. Methods: ISO-CC-005 is a multi-center, phase I/IIa study in mCRC patients eligible for 5-FU/folate therapy alone or in combination with irinotecan or oxaliplatin ± bevacizumab. Patients were also treated with different doses of arfolitixorin as a single or double bolus. The study investigated safety and tolerability of arfolitixorin, and anti-tumor activity was evaluated by overall response rate (ORR) per RECIST v1.1 after 4 cycles of chemotherapy. RNA was prepared from FFPE tumor tissue, reverse transcribed and used for gene expression profiling. The following genes of interest were evaluated: ABCC3, MTHFD2, SLC46A1, SLC19A1, SLC25A32 and TYMS. An ANOVA test was used to rule out potential biases in the baseline expression levels of the genes and to assess the potential association with clinical response. Results: Eighty-one (77.1%) of 105 patients provided material for this analysis. A lower pre-treatment expression of TYMS was associated with clinical benefit (PR and SD; p = 0.021). No clear association was identified between the gene expression markers and the number of adverse events. Gender was not significantly associated with differences in gene expression. Conclusions: Low pre-treatment expression levels of TYMS were associated with clinical benefit (PR and SD) following treatment. Given the role of this gene in the folate metabolic pathways we plan to further assess its predictive potential on a larger cohort during our ongoing global phase III AGENT study. In parallel an assessment of the expression of the other candidate genes on specific patient sub-groups is currently ongoing. These studies will provide additional cues on the use of these genes as predictive markers for treatment outcome and their role in the mode of action of the drug. Clinical trial information: NCT02244632.

Plasma deoxyuridine as a surrogate marker for toxicity and early clinical response in patients with metastatic colorectal cancer after 5-FU-based therapy in combination with arfolitixorin

Purpose

The aim was to explore the correlation between increasing doses of [6R]-5,10-methylenetetrahydrofolate (arfolitixorin) and plasma concentrations of deoxyuridine (dUr) in patients with metastatic colorectal cancer (mCRC), subjected to 5-fluorouracil (5-FU)-based chemotherapy. The aim was further to investigate the possibility to predict toxicity and clinical response during treatment using gender, age, and plasma dUr as explanatory variables.

Methods

Thirty-three patients from the ISO-CC-005 phase I/IIa study, which investigated safety and tolerability of arfolitixorin at four dose levels, were included. Toxicity and clinical response were evaluated after 4 cycles of chemotherapy. Plasma dUr was quantified before (0 h) and 24 h after 5-FU administration at the first (C1) and fourth (C4) cycle using LC–MS/MS. Fit modelling was used to predict toxicity and clinical response.

Results

The dUr levels increased with increasing arfolitixorin dose. Females had higher total and haematological toxicity scores (p = 0.0004 and 0.0089, respectively), and needed dose reduction more often than males (p = 0.012). Fit modeling showed that gender and the dUr levels at C1-0 h and C4-24 h predicted total toxicity (p = 0.0011), whereas dUr C4-0 h alone was associated with gastrointestinal toxicity (p = 0.026). Haematological toxicity was predicted by gender and age (p = 0.0071). The haematological toxicity score in combination with the dUr levels at C1-24 h and C4-24 h predicted early clinical response (p = 0.018).

Conclusion

The dUr level before and during administration of 5-FU and arfolitixorin was predictive for toxicity and early clinical response and could be a potential surrogate marker for thymidylate synthase inhibition in patients with mCRC.

Trial registration

NCT02244632, first posted on ClinicalTrials.gov on September 19, 2014

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04173-2) contains supplementary material, which is available to authorized users.

Complete and long-lasting clinical responses in immune checkpoint inhibitor-resistant, metastasized melanoma treated with adoptive T cell transfer combined with DC vaccination

Development of T cell-directed immune checkpoint inhibitors (ICI) has revolutionized metastatic melanoma (MM) therapy, but <50% of treated patients experience durable responses. This phase I trial (NCT01946373) investigates the safety/feasibility of tumor-infiltrating lymphocyte (TIL) adoptive cell therapy (ACT) combined with dendritic cell (DC) vaccination in MM patients progressing on ICI. An initial cohort (5 patients) received TIL therapy alone to evaluate safety and allow for optimization of TIL expansion protocols. A second cohort (first-in-man, 5 patients) received TIL combined with autologous tumor lysate-loaded DC vaccination. All patients received cyclophosphamide/fludarabine preconditioning prior to, and intravenous (i.v.) IL-2 after, TIL transfer. The DC vaccine was given as five intradermal injections after TIL and IL-2 administration. [¹⁸F]-FDG PET/CT radiology was performed to evaluate clinical response, according to RECIST 1.1 (on the CT part). Immunological monitoring was performed by flow cytometry and T-cell receptor (TCR) sequencing. In the safety/optimization cohort, all patients had a mixed response or stable disease, but none durable. In the combination cohort, two patients experienced complete responses (CR) that are still ongoing (>36 and >18 months, respectively). In addition, two patients had partial responses (PR), one still ongoing (>42 months) with only a small bone-lesion remaining, and one of short duration (<4 months). One patient died early during treatment and did not receive DC. Long-lasting persistency of the injected TILs was demonstrated in blood. In summary, we report clinical responses by TIL therapy combined with DC vaccination in 4 out of 4 treated MM patients who previously failed ICI.

AGENT: An open-label phase III study of arfolitixorin versus leucovorin in modified FOLFOX-6 for first-line treatment of metastatic colorectal cancer

TPS268

Background: 5-fluorouracil (5FU), in combination with folates, is an established cornerstone of metastatic colorectal cancer (mCRC) treatment. All folates currently approved for mCRC need to be metabolically activated to [6R]-5,10-methylenetetrahydrofolic acid ([6R]-MTHF), the active thymidylate synthase co-substrate that potentiates the effect of 5FU. Arfolitixorin does not require multi-step metabolic activation, and may produce higher, and less inter- and intraindividually variable, concentrations of [6R]-MTHF than leucovorin. Methods: The phase III AGENT trial (NCT03750786) is a randomized, multicenter, parallel-group study comparing the efficacy of arfolitixorin versus leucovorin in mCRC patients treated with first-line 5FU, oxaliplatin, and bevacizumab. Patients are randomized (1:1) to the investigational arm (arfolitixorin + 5FU + oxaliplatin [ARFOX] + bevacizumab) or the comparator arm (leucovorin + 5FU + oxaliplatin [modified FOLFOX-6] + bevacizumab), and treated until disease progression based on RECIST 1.1 criteria. Recruitment is ongoing, and aims to randomize 440 patients in 18 months. Eligibility criteria include non-resectable mCRC; eligibility for 5FU, oxaliplatin, and bevacizumab therapy; ECOG PS 0 or 1. The study will be conducted across approximately 100 sites in Australia, Austria, Canada, France, Germany, Greece, Japan, Spain, Sweden, and USA. The primary endpoint is objective response rate. Key secondary endpoints are progression-free survival and duration of response. Additional secondary endpoints include overall survival, quality of life, safety and tolerability, and number of patients undergoing curative metastasis resection. A translational program will evaluate expression levels of several folate metabolism- and transportation-related genes in mCRC tumor biopsies to determine their relationship to treatment outcome. A broad array of genes will analyzed, including ATP-binding cassette C3 (ABCC3) transporter, methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), proton-coupled folate transporter (PCFT), and serine hydroxymethyltransferase 1 (SHMT1). Interim data are expected in mid 2020. Clinical trial information: NCT03750786.

Plasma deoxyuridine levels in metastatic colorectal cancer (mCRC) patients and clinical response after 5FU based therapy in combination with arfolitixorin

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Background: 5-Fluorouracil (5FU) is one of the most commonly used cancer drugs. FdUMP is a metabolite from 5FU which inhibits thymidylate synthase (TS). TS inhibition causes a rise in the intracellular pool of the natural TS substrate dUMP leading to increased global levels of deoxyuridine (dUR). In order to increase TS inhibition, 5FU is combined with folates, usually leucovorin (LV). However, LV needs enzymatic conversion to become active. The LV conversion capacity differs between patients, with the consequence that many patients will have a reduced effect of 5FU-based treatment. Arfolitixorin is a biologically active folate, 5,10-methylenetetrahydrofolate, which doesn´t need enzymatic conversion; hence it could potentially be more efficacious. Methods: ISO-CC-005 is a phase I/II safety and tolerability study in mCRC patients receiving 5FU/arfolitixorin alone or in combination with irinotecan or oxaliplatin ± bevacizumab. Efficacy was evaluated as Overall Response Rate (ORR) after 4 cycles of chemotherapy. A LC-MS/MS method was developed for quantification of plasma dUr and 5FU. Blood samples were collected before and 24 h after 5FU administration at the first (C1) and fourth (C4) treatment cycle (n = 33). The C4/C1 ratio for dUr and 5FU, respectively, were calculated.The clinical response, which is an ordered categorical data, was modelled using nominal logistic regression using the ratio C4/C1 and the absolute values C1 and C4 as explanatory variables. Results: A positive correlation between dUr and 5FU levels was seen (r = 0.89, p = 0.0011) at C4. The C4/C1 ratio for dUr and 5FU in plasma correlated positively (r = 0.95, p = 0.0001). A positive correlation was also found between arfolitixorin dose and plasma levels of dUr (r = 0.44, p = 0.016) at C1, but not at C4. In the model test, the C4/C1 dUr ratio, as well as the individual dUr levels at C1 and C4, had a highly significant effect on ORR (p = 0.0075). Conclusions: The results demonstrate that the arfolitixorin dose has an impact on plasma levels of dUr and also on clinical response. dUr could potentially be an early surrogate marker for TS inhibition in mCRC patients treated with 5FU/arfolitixorin. Clinical trial information: NCT02244632.

Abstract CT032: Adoptive T cell transfer combined with DC vaccination in patients with metastatic melanoma

Background and aim: Although several drugs have been approved that improve overall survival in patients with metastatic melanoma, there is still a need for additional treatments when the approved ones are exhausted. Adoptive T-cell therapy (ACT) has been reported to induce clinical responses in up to 70% of stage IV melanoma patients. The aim of the MAT02 trial is to investigate the toxicity and feasibility of a combined treatment with adoptive transfer of autologous, tumor-derived T cells with or without autologous dendritic cell (DC) vaccination in patients with stage III/IV melanoma.

Method: This study is a single centre, open-label, two-armed, phase I trial. Five patients are assigned to each cohort (A or B) and receive ACT of autologous tumor infiltrating lymphocytes (TIL) without (A) or with (B) autologous tumor loaded DC i.c. Prior to TIL cell transfer, all patients are pre-treated with a precondition regimen. Administration of TIL cells is followed by IL-2 administration (100000 U/Kg q8hx14). Radiological evaluation is performed four weeks after the last DC administration. The primary objective is to evaluate the toxicity and feasibility. The secondary objectives are to generate large numbers of T cells, boost tumor-reactive T cells by DC vaccination, characterize the T cell population used for adoptive transfer with regard to phenotype and functionality, and generate an objective anti-tumour response.

Results: Cohort A in which patients received only TIL has been completed and the treatment was feasible with limited expected toxicity. All treated patients showed a mixed response or stable disease. However, these responses were not durable. The overall survival ranged between 4-17 months. For cohort B which received the combined treatment of TIL and DC vaccine, three patients have completed the treatment that has been feasible with limited expected toxicity. The number of cells transfused in this cohort ranged between 29 and 33 billion and all patients have been administered five DC-vaccinations. All 3 patients responded; one with a complete response which is still ongoing (&gt; 12 mo). Two patients showed a partial response, one with a long lasting response (&gt; 18 mo) and one with a short response (&lt; 4 mo). The accrual continues and we expect to include another two patients before the summer of 2018.

Conclusions: Adoptive T cell therapy combined with DC vaccination is safe with tolerable toxicity profiles and can result in complete clinical response in patients who have failed on checkpoint therapy.

Citation Format: stina L. wickström, Tanja Lövgren, Maria Wolodarski, Ulrika Edbäck, Eva Martell, Karin Markland, Maria Nyström, Andreas Lundqvist, Hans Jacobsson, Johan Hansson, Giuseppe Masucci, Roger Tell, Isabel Poschke, Lars Adamson, Jonas Mattsson, Rolf Kiessling. Adoptive T cell transfer combined with DC vaccination in patients with metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT032.

A phase I clinical trial combining dendritic cell vaccination with adoptive T cell transfer in patients with stage IV melanoma

Adoptive transfer of in vitro-expanded tumor-infiltrating lymphocytes (TIL) has shown great clinical benefit in patients with malignant melanoma. TIL therapy itself has little side effects, but conditioning chemo- or radiotherapy and postinfusion interleukin 2 (IL-2) injections are associated with severe adverse advents. We reasoned that combining TIL infusion with dendritic cell (DC) vaccination could circumvent the need for conditioning and IL-2 support and thus represent a milder treatment approach. Eight patients with stage IV melanoma were enrolled in the MAT01 study, consisting of vaccination with autologous tumor-lysate-loaded DC, followed by TIL infusion. Six of eight patients were treated according to protocol, while one patient received only TIL and one only DC. Treatments were well tolerated with a single grade 3 adverse event. The small study size precludes analysis of clinical responses, though interestingly one patient showed a complete remission and two had stable disease. Analysis of the infusion products revealed that mature DC were generated in all cases. TIL after expansion were CD3+ T cells, dominated by effector memory CD8+ cytotoxic T cells. Analysis of the T cell receptor repertoire revealed presence of highly dominant clones in most infusion products, and many of these could be detected in the circulation for weeks after T cell transfer. Here, we report the first combination of DC vaccination and TIL infusion in malignant melanoma. This combined treatment was safe and feasible, though after evaluating both clinical and immunological parameters, we expect that administration of lymphodepleting chemotherapy and IL-2 will likely increase treatment efficacy.

Multicentre phase II trial of paclitaxel and carboplatin with concurrent radiotherapy in locally advanced non-small cell lung cancer

AIM

To evaluate weekly induction chemotherapy followed by weekly concomitant chemoradiotherapy in a multicentre phase II study of patients with unresectable stage III non-small cell lung cancer (NSCLC; stage wet IIIB excluded).

PATIENTS AND METHODS

Eligible patients received three weekly cycles of paclitaxel 100 mg/m2 and carboplatin AUC2 followed by six weekly cycles of paclitaxel 60 mg/m2 and carboplatin AUC2 in combination with thoracic radiotherapy (2 Gy per fraction and day to a total dose of 60 Gy).

RESULTS

Sixty-four patients (40 males and 24 females) with a median age of 63 years (range, 43-79 years) entered the study. T and N stage were distributed as follows: T1 2 patients (3.2%), T2 10 patients (15.6%), T3 15 patients (23.4%), T4 37 patients (57.8%); N0 10 patients (15.6%), N1 1 patient (1.6%), N2 26 patients (40.6%), N3 26 patients (40.6%), and N missing 1 patient (1.6%). Seven patients (10.9%) suffered from grade 3/4 oesophagitis. Grade 1/2 oesophagitis occurred in 36 patients (56.3%) and pneumonitis grade 1/2 occurred in 10 patients (15.6%). Sixty-three patients were evaluated on an intent-to-treat basis. The overall response rate was 74.6%. The median time to progression was 247 days and median overall survival was 461 days. According to subgroup analyses, no statistically significant differences were noted according to gender, age (<65 vs. > or =65 years), performance status, histology, or study centre.

CONCLUSION

Induction chemotherapy followed by concurrent chemoradiotherapy with weekly cycles of paclitaxel and carboplatin is feasible and generates moderate toxicity. Efficacy is comparable to other recently published regimens. However, prognosis remains, in general, poor for this group of patients and further work to develop better therapy is required.

Long-term incidence of hypothyroidism after radiotherapy in patients with head-and-neck cancer

PURPOSE

To determine the long-term incidence of postirradiation hypothyroidism (HT) in patients with head-and-neck cancer.

METHODS AND MATERIALS

The incidence of overt HT was assessed prospectively in 391 patients with nonthyroid head-and-neck cancer admitted for radiotherapy (RT) consecutively between 1990 and 1996. Eighty-three patients were excluded from the analysis because of known thyroid disease before treatment (n = 27), no RT was given (n = 15), or inadequate follow-up (n = 41). Overt HT was defined as increased thyroid-stimulating hormone (TSH) in combination with decreased fT4/T4 or in combination with initiation of thyroxine replacement therapy.

RESULTS

With a median follow-up of 4.2 years (range, 3 months to 10.9 years) for 308 evaluable patients, the 5- and 10-year Kaplan-Meier actuarial risks of HT were 20% and 27%, respectively. The median time until development of HT was 1.8 years (3 months to 8.1 years). Multivariate analysis showed that patients with bilateral RT to the neck had a higher risk of HT in comparison with unilateral neck RT (relative hazard, 0.37; p = 0.02). The addition of surgery to RT increased the overall risk of HT (p < 0.001); and if surgery involved the thyroid gland, the relative hazard was 4.74 (p < 0.001). For an elevated pre-RT TSH value, the relative hazard was 1.58 (p < 0.001).

CONCLUSION

The incidence of overt HT after locoregional RT for nonthyroid head-and-neck cancer continues to increase with time, even after long-term follow-up. We recommend life-long TSH testing in these patients.

Radiation-induced cell cycle response in lymphocytes is not related to clinical side-effects in breast cancer patients

BACKGROUND

We examined whether development of radiation-induced lung injury after irradiation for breast cancer correlates with lymphocyte radiosensitivity (LRS) in vitro.

MATERIALS AND METHODS

Patients were selected from a cohort of 177 patients, who were treated with adjuvant postoperative radiotherapy (RT) for loco-regional breast cancer, and included 14 patients who had severe early lung injury measured as respiratory symptoms caused by RT and treated with corticosteroids (i.e. "cases") and a corresponding 14 control patients without such symptoms. LRS was measured as the postirradiation fraction of mitogen-stimulated blood lymphocytes in S- and G2-phase. Plasma levels of TGF-beta 1 and thiols, both suggested to be involved in the pathogenesis of radiation-induced lung injury, were also analysed.

RESULTS

The result showed that cells from the controls responded to a higher extent to mitogen stimulation than cells from the cases (p < 0.05). Analysis of the fraction of S- and G2-phase cells after irradiation showed no significant difference between the two groups (p = 0.57 and 0.31, respectively). There was no difference in plasma levels of TGF-beta 1 and thiols in patients who did or did not develop pulmonary injury after RT. Tamoxifen administered before or at RT did not influence the incidence of pulmonary reactions.

CONCLUSION

No differences in LRS were found between breast cancer patients with lung complications after RT and matched control patients without complications.

Expression of Ku86 confers favorable outcome of tonsillar carcinoma treated with radiotherapy

BACKGROUND

To determine possible molecular markers for predicting radiosensitivity in squamous cell carcinoma, we have examined the relationship between pretreatment expression of the DNA damage recognition complex DNA-PK, its in vitro substrates, p53 and MDM2, local tumor control after radiotherapy (RT), and patient survival.

METHODS AND MATERIALS

Formalin-fixed tumor biopsy specimens from 79 previously untreated patients with tonsillar carcinoma were analyzed by immunohistochemical methods.

RESULTS

Tumors expressing high levels of Ku86 had better locoregional control in contrast to tumors expressing low levels of Ku86 (p =.023). Survival of patients with tumors expressing high levels of DNA-PKcs was significantly better than survival of patients with tumors expressing low levels of DNA-PKcs (p =.0024). p53 and MDM2 status alone did not correlate with survival of patients. However, patients with p53 tumors and high DNA-PKcs expression had significantly better survival than patients with p53+ tumors expressing low levels of DNA-PKcs (p =.0018). Furthermore, survival of patients with high expression of DNA-PKcs or Ku86 and low MDM2 levels was significantly better when compared with survival of patients with low DNA-PKcs or Ku86 and high MDM2 (p =.0017 and p =.0034, respectively).

CONCLUSIONS

High expression of DNA-PKcs/Ku86 in combination with p53 negativity in tonsillar carcinoma correlates with better survival of patients. Identifying tumors with a phenotype predicting poor survival may be used to optimize treatment of patients with radioresistant tumors.

Magnetic fields from steel-belted radial tires: implications for epidemiologic studies

Magnetic fields emanate from radial tires due to the presence of reinforcing belts which are made of magnetized steel wire. When these tires spin, they generate alternating magnetic fields of extremely low frequency (ELF), usually below 20 Hz. The fundamental frequency of these fields is determined by tire rotation rate and has a sinusoidal waveform with a high harmonic content. The static field of radial tires can exceed 500 microT at the tread, and the tire-generated alternating fields can exceed 2.0 microT at seat level in the passenger compartment of vehicles. Degaussing the tires reduces both the static and alternating fields to low levels, but the fields increase gradually over time after degaussing. The tire-generated fields are below the frequencies detected by most of the magnetic field meters used in previous studies of power frequency magnetic field health effects. If these fields are biologically active, failure to detect them could compromise exposure assessments associated with epidemiologic studies.

Comparison between radiation-induced cell cycle delay in lymphocytes and radiotherapy response in head and neck cancer

A study was made evaluating the use of radiation-induced cell cycle delay in lymphocytes to predict tumour response to radiotherapy. Peripheral blood lymphocytes were isolated from whole blood from 49 patients with head and neck cancer before treatment with radiotherapy and from 25 healthy donors. The clinical response to radiotherapy was assessed at 0-2 months after treatment. The level of radiation-induced cell cycle delay was measured using flow cytometry after mitogen stimulation of lymphocytes. The analysis of ten normal donors gave no significant difference in variability between the intra-assay and the intra-donor samples. However, the cell cycle data for lymphocytes from these healthy donors showed significant inter-individual differences in G2 phase accumulation. Patients showing no response to radiotherapy had a high level of S-phase cells compared with partial (P < 0.001) and complete responders (P = 0.016). An inverse relationship was found when analysing the fraction of cells in G2 (P = 0.009 and 0.034 respectively). In general, healthy donors had similar cell cycle kinetics compared with the non-responders. In conclusion, the result indicates that radiation-induced cell cycle delay in lymphocytes is inversely correlated with tumour response to radiotherapy in head and neck cancer patients. However, the value of the present test for predicting individual tumour response is limited, because of assay variability and overlap between groups.

Hypothyroidism after external radiotherapy for head and neck cancer

PURPOSE

To study the development of thyroid hypofunction in patients with head and neck cancers admitted for external radiotherapy.

METHODS AND MATERIALS

Between November 1990 and July 1996, thyroid function was measured in 264 consecutive patients, where the entire thyroid gland or part of it was included in the target volume. The time to development of hypothyroidism (HT) was calculated from the start of the radiotherapy.

RESULTS

The median follow-up period was 19 months. Seventeen patients (6%) developed elevated serum thyroid-stimulating hormone levels with depressed (free) thyroxine levels (i.e., clinical HT). Elevated serum thyroid-stimulating hormone level with normal (free) thyroxine levels (i.e., chemical HT) developed in 57 (22%). The median time to clinical HT was 15 months (range: 7 to 32). The median time to chemical HT was also 15 months (range: 2 to 28). The actuarial risk of developing clinical or chemical HT 3 years after treatment was 15 and 40%, respectively. The incidence of chemical HT was significantly higher (p = 0.041) when the whole thyroid was included in the target volume compared to patients where only part of the thyroid was irradiated. The same trend was seen as regards clinical HT (p = 0.063). For those 20 patients who underwent laryngectomy, there was an increased risk of both chemical and clinical HT (p = 0.011 and 0.019, respectively). Increasing age was associated with an increased risk of chemical HT (p = 0.001), but not of clinical HT (p = 0.553). Sex, tumor site, radiation dose, and combination of radiotherapy and chemotherapy were not significant factors for thyroid hypofunction.

CONCLUSION

Depressed thyroid function is common after external radiotherapy for cancers of the head and neck. Routine testing for possible thyroid hypofunction should be included in the follow-up procedures, even many years after end of radiotherapy.

Optical fiber communication experiment at 5 Gbit/sec

A Gbit/sec optical fiber communication experiment was performed. The maximum speed was 3 Gbit/sec with a BH laser and 5 Gbits/sec with a TJS laser. A 500-m single-mode fiber was used, and the power was coupled by mounting the laser butt-end to the fiber, giving a minimum loss of 10 dB. The receiver employed a Si-avalanche photodiode with an impulse-response width of 210 psec (FWHM) and a 10-Gbit/sec and gate built from GaAs MESFETs. Bit-error-rate measurement values of <10(-9) prove the feasibility of optical fiber transmission at 5 Gbit/sec.