Radiosensitizing effect of the novel Hsp90 inhibitor NVP-AUY922 in human tumour cell lines silenced for Hsp90α

BACKGROUND

Hsp90 inhibitors can enhance the tumour sensitivity to ionising radiation (IR). However, Hsp90 inhibition leads to the up-regulation of anti-apoptotic Hsp90 and Hsp70, which might diminish the radiosensitizing effects of the inhibitors. Therefore, inhibition of the up-regulation of Hsp90 by siRNA might be a promising strategy to enhance drug-mediated radiosensitization.

MATERIALS AND METHODS

The expression of Hsp90α was silenced in A549 and GaMG tumour cell lines by siRNA treatment. Pre-silenced for Hsp90α cells were treated with NVP-AUY922, a novel Hsp90 inhibitor, for 24 h and then irradiated. Radiation response was determined by colony-forming ability. The expression of several marker proteins was analysed by Western blot. DNA damage and repair were assessed by histone γH2AX measurements.

RESULTS

We found that transfection with siRNA against Hsp90α reduced Hsp90α at mRNA and protein levels. Pre-silencing of Hsp90α reduced NVP-AUY922-mediated up-regulation of Hsp90α but it did not increase drug-mediated radiosensitization in both tumour cell lines. As revealed by Western blot, pre-silencing of Hsp90α followed by NVP-AUY922 did not change the expression of Hsp90 client proteins (Akt, Raf-1, Cdk1 and Cdk4) compared with drug treatment alone, suggesting unchanged chaperone function in transfected cells.

CONCLUSION

Pre-silencing of Hsp90α followed by Hsp90 inhibition did not enhance the radiosensitizing effect of NVP-AUY922 in both tested tumour cell lines. Future work will be done on stable transfection with shRNA against Hsp90α or simultaneous silencing of both Hsp90 isoforms, Hsp90α and Hsp90β, in order to optimize tumour cell killing.

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.

Final analysis of a multicenter, randomized phase II trial comparing three different chemoradiotherapy regimens in the treatment of patients with locally advanced, nonmetastatic pancreatic cancer

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Background: To date, no standard treatment approach for patients (pts) with non-resectable, locally advanced pancreatic cancer (PC) is defined. Methods: Within a prospective phase II trial treatment-naive pts with locally advanced PC and adequate organ function were randomly assigned to three different CRT regimens; all pts received a conventionally fractionated radiotherapy of 50 Gy (with a daily dose of 2.0 Gy) and were randomized to either concurrent 5-FU as a 24h-infusion (350 mg/m2/d on each day of radiotherapy, RT-5FU arm), concurrent low-dose gemcitabine 300 mg/m2 and cisplatin 30 mg/m2 on days 1, 8, 22, and 29 (RT-GC arm), or the same concurrent treatment followed by a sequential chemotherapy with full- dose gemcitabine (1000 mg/m2) and cisplatin (50 mg/m2) every two weeks (RT-GC+GC arm). Treatment duration in the RT- GC+GC arm was upon disease progression or unacceptable toxicity. The primary study endpoint was the overall survival (OS) rate after 9 months (mo); secondary endpoints included response rate (WHO criteria), progression-free survival (PFS), resectability and toxicity. Results: Ninety-five patients (median age 64 years, 54% male, 50% KPS 90–100%) were recruited from 12 German centers. Seventy patients were evaluable for objective response: the intent-to-treat response rate (CR+PR) was 19% in the RT-5FU arm, 22% in the RT-GC arm and 13% in the RT-GC+GC arm, respectively. Overall, 18 pts (19%) underwent surgical resection after initial CRT (R0 in 8 pts). After a median follow-up of 8.6 mo, median PFS was estimated with 4 mo (RT-5FU), 5.6 mo (RT-GC) and 6 mo (RT- GC+GC), respectively (p=0.21). The corresponding median OS times were 9.6 mo, 9.3 mo and 7.3 mo (p=0.61). Hematological grade 3/4 toxicities were higher in the two gemcitabine/cisplatin-containing arms, but no grade 3/4 febrile neutopenia was observed. Regarding non-hematological toxicity, nausea/vomiting were more frequently in the RT-GC and RT-GC+GC arm, whereas diarrhea was more frequent in the RT-5FU arm. Conclusions: Based on these data, gemcitabine/cisplatin-based CRT does not achieve a higher clinical efficacy compared to RT-5FU, and is associated with increased hematological toxicity.

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[Requirements and performance profile of the Paediatric Radiation Oncology Working Group (APRO): evaluation of the present situation and description of future developments]

BACKGROUND

Radiation therapy is an integral component in the management of childhood malignancies and undergoes a continuous process of optimization within the prospective trials of the GPOH. At present there are approximately 20 active protocols, some specifying radio-oncological study questions, in which about 500 to 600 children annually are given radiotherapy.

MATERIALS/METHODS

The Pediatric Radiation Oncology Working Group (APRO) of the German Society for Radiation Oncology (DEGRO) represents the organizational link between GPOH and DEGRO. Their activities range from phrasing guidelines of radio-oncological therapy, through writing a protocol for a prospective study on radiation-induced late effects (RISK--in co-operation with GPOH, 695 patients registered so far) and organizing meetings for information transfer, to implementing radio-oncology within the prospective studies of the GPOH by establishing study chairs for radio-oncology when radio-oncological questions are a primary focus and/or to function as a reference institution for quality assurance. These activities also include individual case consultations outside the study proper. Twice annually the members of the APRO meet for an update on current knowledge and future directions where a representative of the GPOH is invited to contribute special aspects of pediatric oncology.

CONCLUSIONS

In the future, modern technology (intensity modulated radiotherapy, proton therapy, inclusion of imaging in treatment planning) will be part of disease management in pediatric oncology. A working group for modern radiotherapy technology was established to enhance this development. Prospective studies of the GPOH with primary or secondary radio-oncological questions require the implementation of corresponding tasks (documentation, monitoring, etc.) in order to meet future demands on clinical trials and to achieve the aims of the protocol. Consequently adequate financial support is indispensable.

Relapse Pattern After Complete Resection and Early Progression After Incomplete Resection of Childhood Craniopharyngioma

In HIT Endo data on therapy and prognosis of 306 patients with childhood craniopharyngioma (CP) were analyzed. The 5 years-overall survival rate was 94 +/- 4 % in irradiated patients and 93 +/- 5 % in non-irradiated patients. Aims of the prospective study KRANIOPHARYNGEOM 2000 were to collect data on the incidence and time course of relapses after complete surgery and tumour progressions after incomplete resection. Furthermore, the impact of irradiation therapy (XRT) on tumour relapse and recurrence rates was analyzed. Since 2001 ninety-eight patients with CP were recruited at a median age at diagnosis of 9.9 years ranging from 1.8 to 18.0 years. Complete resection was achieved in 44 %, incomplete resection in 54 %. XRT was performed in 24 of 98 CP patients; in 10 early after incomplete resection, in 14 of 24 after progression of residual tumour or relapse, in 3 of 14 after second surgery of relapse. XRT was performed at a median age of 12.0 years ranging from 5.0 to 18.9 years and in median after an interval of 9 months after first diagnosis. The analysis of event-free survival rates (EFS) in patients with CP showed a high rate of early events in terms of tumour progression after incomplete resection (3y-EFS: 0.22 +/- 0.09) and relapses after complete resection (3y-EFS: 0.60 +/- 0.10) during the first three years of follow-up. A high rate of early events (1y-EFS: 0.78 +/- 0.10; 2y-EFS: 0.57 +/- 0.15) was also found for patients after XRT (3 cystic progressions, 3 progressions of solid tumour; in 24 patients after XRT). We conclude that tumour progression and relapse are frequent and early events even in irradiated patients. Monitoring of cerebral imaging and clinical status is recommended in follow-up of patients with childhood CP. In order to analyze the appropriate time point of XRT after incomplete resection, QoL, EFS and overall survival in patients (age > or = 5 years) will be analyzed in KRANIOPHARYNGEOM 2007 after stratified randomization of the time point of irradiation after incomplete resection (early irradiation versus irradiation at progression of residual tumour).