Radiosensitization by BRAF inhibitor therapy-mechanism and frequency of toxicity in melanoma patients

BACKGROUND

Recent evidence suggests that ionizing radiation may be associated with unexpected side-effects in melanoma patients treated with concomitant BRAF inhibitors. A large multicenter analysis was carried out to generate reliable safety data and elucidate the mechanism.

METHODS

A total of 161 melanoma patients from 11 European skin cancer centers were evaluated for acute and late toxicity, of whom 70 consecutive patients received 86 series of radiotherapy with concomitant BRAF inhibitor therapy. To further characterize and quantify a possible radiosensitization by BRAF inhibitors, blood samples of 35 melanoma patients were used for individual radiosensitivity testing by fluorescence in situ hybridization of chromosomal breaks after ex vivo irradiation.

RESULTS

With radiotherapy and concomitant BRAF inhibitor therapy the rate of acute radiodermatitis ≥2° was 36% and follicular cystic proliferation was seen in 13% of all radiotherapies. Non-skin toxicities included hearing disorders (4%) and dysphagia (2%). Following whole-brain radiotherapy, rates of radiodermatitis ≥2° were 44% and 8% (P < 0.001) for patients with and without BRAF inhibitor therapy, respectively. Concomitant treatment with vemurafenib induced acute radiodermatitis ≥2° more frequently than treatment with dabrafenib (40% versus 26%, P = 0.07). In line with these findings, analysis of chromosomal breaks ex vivo indicated significantly increased radiosensitivity for patients under vemurafenib (P = 0.004) and for patients switched from vemurafenib to dabrafenib (P = 0.002), but not for patients on dabrafenib only. No toxicities were reported after stereotactic treatment.

CONCLUSION

Radiotherapy with concomitant BRAF inhibitor therapy is feasible with an acceptable increase in toxicity. Vemurafenib is a more potent radiosensitizer than dabrafenib.

Phase I trial of dose-escalated cisplatin with concomitant cetuximab and hyperfractionated-accelerated radiotherapy in locally advanced squamous cell carcinoma of the head and neck

BACKGROUND

Cetuximab is active in the treatment of squamous cell carcinoma of the head and neck (SCCHN), enhancing both radiotherapy and chemotherapy effects. This phase I study was designed to investigate the safety and tolerability of combining weekly cisplatin treatment with cetuximab and hyperfractionated-accelerated radiotherapy (HART) for locally advanced SCCHN.

PATIENTS AND METHODS

Patients with unresectable stage III or IVA/B SCCHN were treated with cetuximab, 400 mg/m² initial dose on day -7 of HART, followed by 250 mg/m² weekly during the administration of HART, which started with 2.0 Gy/day (5 days/week) for 3 weeks followed by 1.4 Gy/twice-daily (Monday to Friday) for another 3 weeks, resulting in a total dose of 70.6 Gy. Cisplatin was administered weekly starting on the first day of radiotherapy until week 6. Cisplatin was dose escalated of four dose levels from 20 to 40 mg/m² using a classical 3 + 3 dose escalation algorithm.

RESULTS

Eighteen patients were enrolled. Sixteen patients were eligible for toxicity, and 15 for response. No maximum tolerated dose was reached for cisplatin. One of six patients of dose level 4 had grade 4 neutropenia. This patient died 1 week after the end of the study treatment. The most common types of grade 3+ adverse events were mucositis (9 of 16 patients), in-field dermatitis (6 of 16 patients) and neutropenia (4 of 16 patients). Cetuximab-related hypersensitivity was observed in 1 out of 18 patients. Six weeks after the end of the study treatment, 5 complete responses, 8 partial responses and 1 progressive disease (at distant sites) were documented in a total of 15 patients (objective response rate 87%).

CONCLUSIONS

The combination of cisplatin with cetuximab and HART is active, well tolerated and merits additional investigation. The recommended weekly dose of cisplatin for phase II studies is 40 mg/m².

Technical report: Radiation sensitivity testing by fluorescencein‐situhybridization: how many metaphases have to be analysed?

PURPOSE

The technique of three-colour fluorescence in-situ hybridization (FISH) is generally regarded as 'gold standard' for detecting chromosomal aberrations. The question was: how many metaphases should be counted to get reliable results?

MATERIAL AND METHODS

Peripheral blood lymphocytes were irradiated in vitro (2.0 Gy). Metaphase chromosomes (1, 2, 4) were labelled by means of three-colour FISH and chromosomal aberrations (breaks per metaphase [B/M], complex chromosomal rearrangements per metaphase [CCR/M]) were analysed. To evaluate the correlation between the number of metaphases counted and the reliable detection of the rate of break events, B/M and CCR/M were scored using 250-1,000 metaphases in steps of 50 unirradiated cells, and from 50 to 200 metaphases in steps of 10 after 2 Gy.

RESULTS

Analysing spontaneously occurring aberrations, B/M values based on 500 and 750 counted metaphases agreed well with those B/M values from 1,000 scored metaphases. After counting 150 metaphases after 2 Gy, the confidence interval of B/M values was about 44% smaller and the confidence interval of CCR/M values was about 41% smaller compared with values obtained after counting 100 metaphases.

CONCLUSIONS

Scoring the number of spontaneous aberrations, reliable results can be obtained after counting 500 metaphases. After 2 Gy, a minimum of 150 metaphases should be analysed.

A phase III trial of topotecan and whole brain radiation (WBRT) therapy for patients with CNS metastases due to lung cancer

2049

Background: Brain metastases represent an important cause of morbidity in patients (pts) with lung cancer and are associated with a mean survival of less than 6 months. Thus studies to improve outcome are urgently needed. Methods: Based on promising data raised in a phase I/II trial, in which WBRT was combined with topotecan (ASCO #444, 2003), we initiated an open, randomized, prospective, multicentric phase III trial, comparing WBRT (20 x 2 Gy; arm A) alone with WBRT + topotecan (0.4 mg/m2/d x 20; arm B). 320 pts with CNS-metastases due to SCLC or NSCLC were projected. Primary endpoint was overall survival (OS), secondary endpoints were local response and progression-free survival (PFS). However, since until the cut off date of study completion (i.e. a study duration of 34 months) only a total of 96 (A: 49, B: 47) pts have been recruited, an interim analysis was performed at that time point. Results: The demographic data (ø age 59 (34–75), 64% male, 66% NSCLC, mainly (64%) ECOG 0–1, extracerebral metastases in 75% and more than 4 cerebral lesions in 26% of pts) were evenly distributed in the two groups. Also the rate of grade 3/4 toxicities (besides alopecia 115 non-hematological (A/B: 60/55) and 43 hematological events (18/25)) did not differ remarkably between the arms. Early deaths (within 6 weeks after recruitment) occurred in 24% of the patients (A/B: 30%/18%), mainly due to tumor progression. Local response, evaluated 2 weeks after treatment, was assessable in 44 (A/B: 21/23) pts, showing CR in 8 (5/3), PR in 17 (6/11), SD in 14 (6/8) and PD in 5 (4/1) pts (all differences n.s.). Neither PFS (median A/B; days: 76/97, range, 24–251/20–428) nor OS (median A/B; days: 95/87, range 4–433/3–752) differed significantly (Cox-Mantel test; p=0.82 and 0.43, respectively). Conclusions: The available data, gained from the only phase III trial regarding concurrent WBRT and topotecan, show no significant advantage for concurrent radiochemotherapy for patients with lung cancer, however due to the limited number of recruited patients a possible small advantage of a combined treatment could not be demonstrated. Based on these results and the slow recruitment a continuation of the study did not seem reasonable.

No significant financial relationships to disclose.

Radiation-induced impairment of osseous healing with vascularized bone transfer: experimental model using a pedicled tibia flap in rat

Aim of this study was to establish an appropriate animal model for investigating the healing of vascularized osseous transplants to irradiated recipient sites applying metabolic, vascular and immunologic experimental studies. In 20 Wistar rats (male, weight 300-500 g), a pedicled osseous tibia flap was raised and transferred to a subcutaneous pocket in the ipsilateral groin. The remaining tibia was stabilized with a monocortical titanium miniplate. To create a pre-irradiated transplant bed, the donor-area including the adjacent bone of the tibia was irradiated with a total dose of 50Gy (5 x 10 Gy) in 10 animals. The interval between irradiation and retransfer of the non-irradiated pedicled tibia flap was 4 weeks. Ten animals received no radiation. Evaluation of osseous healing and the success of the transferred flap were based on a clinical and quantitative histomorphometric assessment. Testing for significant differences was performed using the non-parametric Mann-Whitney U-test. The rate of complete osseous healing in the non-irradiated animals was 90%. In contrast there was no significant bone union observed in the group of the pedicled flaps grafted to the pre-irradiated (50Gy) recipient site (P = 0.001). Similarly bone formation in the transitional zone between bone graft and recipient bone was significantly lower in the preirradiated group (P < 0.001) (16.9 +/- 3%) in contrast to the non-irradiated transplant bed (47.9 +/- 6%).

Plattenepithelkarzinome der Mundh�hle

INTRODUCTION

In patients with oral cancer the treatment has a strong impact on the quality of life. In recent years different therapeutic concepts have been developed, which include preoperative simultaneous 'neoadjuvant' radiochemotherapy (RCT) and one-stage surgery with tumour ablation and reconstruction. Consideration of long-term survival rates yields substantial evidence that mixed-modality treatment including neoadjuvant RCT is superior to adjuvant therapy concepts based on a surgical approach with postoperative radiation.

PATIENTS AND METHODS

In this nonrandomised longitudinal prospective study quality of life was evaluated in two groups made up of a total of 53 patients with squamous cell carcinoma of the oral cavity, 26 of whom underwent neoadjuvant radiochemotherapy with subsequent surgical resection while the remaining 27 received surgical treatment first and then postoperative radiotherapy. The quality-of-life core questionnaire (QLQ C-30) and the head and neck cancer module (H&N 35) of the European Organisation for Research and Treatment of Cancer (EORTC) were used. Long-term survival was estimated according to the Kaplan-Meier test.

RESULTS

Postoperatively both groups showed a marked reduction in quality of life, especially in restricted chewing, swallowing and speaking. One year later their quality of life had improved substantially, though without quite reaching the preoperative quality-of-life scores. Both groups showed specific impairments in the symptom scales. With adjustment for the fact that the patients were not randomised, long-term survival was 78% in the neoadjuvant treatment group and 50% in the adjuvant treatment group.

CONCLUSION

Temporary limitations in the quality of life can be expected after tumour treatment of the kinds presented here for oral cancer. Neoadjuvant therapy concept is more aggressive and might result in longer disease-free survival. The primary goal should be eradication of the tumour. Nevertheless preservation or reconstruction of a maximum of function is essential for a high level of quality of life. Combined-modality treatments seem to be superior to any kind of monotherapy and should therefore be preferred.

Neoadjuvant radio-chemotherapy in advanced primarilynon-resectable carcinomas of the pancreas

AIM

To investigate the feasibility of neoadjuvant radio-chemotherapy (RCT) in the treatment of primarily non-resectable pancreas carcinoma the parameters tumour regression, possibility of subsequent resection and tolerability were examined.

METHOD

Between 1995 and 1997, 27 patients with locally inoperable (assessed by CT criteria) pancreatic carcinoma received radio-chemotherapy for 5 weeks comprising irradiation (55.8 Gy) and chemotherapy with 5-fluorouracil (5-FU, 1000 mg/m(2)/day; 120 h continuous infusion) and mitomycin C (10 mg/m(2)i.v.-bolus, day 2 and day 30) during the first and fifth week of radiotherapy. Two target volumes were irradiated with fractionated doses of 1.8 Gy up to a total of 50.4 Gy. Radiation was applied once a day five times a week and target volume 1 was irradiated with the same fractionated dose, and an additional boost of 5.4 Gy to make an overall total of 55.8 Gy.

RESULTS

Sixteen patients underwent explorative laparotomy, 10 of these were resected (eight Whipple's procedures, two distal pancreatic resections), while six could not be resected due to peritoneal carcinosis (n=3), local irresectability (n=2) and liver cirrhosis (n=1). A further nine patients were found to have unresectable tumours on CT and did not undergo surgery after restaging (five of these patients were staged as <<locally irresectable>>, three patients had distant metastases and one patient refused surgery). In two patients RCT was abandoned because of progression of disease.

CONCLUSIONS

The study protocol described is feasible without significant acute toxicity and when used the resectability rate was improved; the survival rate, however, was not improved. Additional intra-arterial or intraportal application of such drugs as mitomycin C or cisplatin may be necessary.

Early results of pulsed-dose-rate interstitial brachytherapy for head and neck malignancies after limited surgery

PURPOSE

The aim of this study was to evaluate the relative incidence of toxicity and local control in patients with head and neck malignancies who underwent interstitial pulsed-dose-rate (PDR) brachytherapy (iBT).

PATIENTS AND METHODS

From October 1997 to December 1998, 61 patients underwent interstitial PDR brachytherapy procedures in our department; 47 were patients with head and neck cancer. Forty patients received brachytherapy as part of their curative treatment regimen, and 7 patients were implanted for palliative purposes and excluded from the analysis of therapy efficacy. Twenty-four patients had interstitial brachytherapy procedures alone with D(REF) = 50 Gy; in 23 patients, iBT procedures were performed with D(REF) = 24 Gy in combination with external radiation. A dose per pulse (dp) of 0.5 Gy was prescribed for 38/47 patients, and a dp = 0.7 Gy for 9/47 patients. The pulses were delivered 24 h a day, with a time interval of 1 h between two pulses, resulting in an effective dose rate of 0.5 Gy/h or 0.7 Gy/h. A follow-up of the patients was done to analyze acute and delayed toxicity, local control, and survival. The analysis was performed after median follow-up of 12 months (5-18 months).

RESULTS

After a median follow-up of 12 months, soft tissue necrosis was seen in one patient and bone necrosis in another. No other serious side effects were observed. Permanent locoregional tumor control was achieved in 37 of 40 patients. No distant metastases were observed.

CONCLUSIONS

PDR interstitial brachytherapy with 0.5-0.7 Gy/h is a safe therapy. These preliminary results suggest that PDR interstitial brachytherapy of head and neck cancer is comparable with low-dose-rate (LDR) brachytherapy.

[Prognostic factors in combined radiochemotherapy of the anal canal carcinoma]

Combined radiation and chemotherapy is an effective treatment for all stages of carcinoma of the anal canal. Abdominoperineal resection is reserved for patients with incomplete regression of tumor or recurrent carcinoma.

[Needle tract metastasis following sonographically guided puncture of a mesenteric lymph node metastasis in Pancoast's tumor]

Peripheral bronchial carcinoma with infiltration of the right lateral thoracic wall (Pancoast tumour) was demonstrated in a 60-year-old man with breathing-related pain in the right thoracic wall of two months' duration. As part of tumour staging needle puncture of an intra-abdominal space-occupying lesion was performed, guided by ultrasonography. Histological examination confirmed it as a bronchial carcinoma metastasis. Combined radio- and chemotherapy hardly influenced tumour growth. Three months later a subcutaneous lesion became palpable in the area of the previous needle puncture which on excision proved to be a metastasis. The patient died 10 months later from the bronchial carcinoma. Percutaneous puncture of potentially malignant space-occupying lesions must be strictly indicated. The frequency of needle tract seeding is not exactly known.

[In vivo dosimetry in interstitial "low dose rate" afterloading therapy with Ir-192 seeds exemplified with head-neck tumors]

An in vivo measuring method is introduced from mending the calculated lying time of implants corresponding to the given dose (reference dose) in the interstitial brachytherapy with iridium-192 seeds. The small effort for using this method and the relatively easy way of handling it allow its clinical use for quality assurance in brachytherapy.