Antibody targeting of anaplastic lymphoma kinase induces cytotoxicity of human neuroblastoma

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase aberrantly expressed in neuroblastoma, a devastating pediatric cancer of the sympathetic nervous system. Germline and somatically acquired ALK aberrations induce increased autophosphorylation, constitutive ALK activation and increased downstream signaling. Thus, ALK is a tractable therapeutic target in neuroblastoma, likely to be susceptible to both small-molecule tyrosine kinase inhibitors and therapeutic antibodies-as has been shown for other receptor tyrosine kinases in malignancies such as breast and lung cancer. Small-molecule inhibitors of ALK are currently being studied in the clinic, but common ALK mutations in neuroblastoma appear to show de novo insensitivity, arguing that complementary therapeutic approaches must be developed. We therefore hypothesized that antibody targeting of ALK may be a relevant strategy for the majority of neuroblastoma patients likely to have ALK-positive tumors. We show here that an antagonistic ALK antibody inhibits cell growth and induces in vitro antibody-dependent cellular cytotoxicity of human neuroblastoma-derived cell lines. Cytotoxicity was induced in cell lines harboring either wild type or mutated forms of ALK. Treatment of neuroblastoma cells with the dual Met/ALK inhibitor crizotinib sensitized cells to antibody-induced growth inhibition by promoting cell surface accumulation of ALK and thus increasing the accessibility of antigen for antibody binding. These data support the concept of ALK-targeted immunotherapy as a highly promising therapeutic strategy for neuroblastomas with mutated or wild-type ALK.

[High-dose chemotherapy and residual tumor resection in male germ cell tumors]

As a consequence of the unsatisfactory results of conventional dose salvage regimens, in particular for patients with poor prognostic features at the time of relapse or in patients with refractory disease, high-dose chemotherapy (HDCT) was introduced into clinical practice in the late 1980s. The combination of carboplatin and etoposide (CE) still remains the backbone of most high-dose regimens. Multiple modifications with more dose escalations or addition of further drugs have been explored, most often with increased toxicity. With improved expertise in supportive care and the use of peripheral blood stem cells, hematopoetic recovery has been significantly shortened and the initial high treatment-related mortality reduced from more than 10% to about 3%. Since the incorporation of HDCT, even patients with unfavorable prognostic features or patients with second or subsequent relapses can achieve long-term remission. Following HDCT residual tumor resection plays a major role in achieving these long-term results. The proportion of vital residual tumor after HDCT is much higher than in patients after conventional chemotherapy. The role of HDCT remains controversial particularly as a first-line treatment and less so in the first salvage setting. As these patients are rare HDCT and residual tumor resection should only be be provided by high-volume centers with sufficient expertise in performing these complex procedures.

Pathohistologic findings in patients with nonseminomatous germ cell tumors (NSGCT) who undergo postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) for small tumors

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Background: The current guidelines recommend the resection of all visible residual tumors in NSGCT after a cisplatin based chemotherapy. There are controversial data concerning the necessity of PC-RPLND in patients with residual tumours less than one centimetre in diameter. The aim of our study was to evaluate the pathological findings in a modern series with regard of the residual tumour size.

Methods: A retrospective analysis of the patient's charts was performed including patients who underwent PC-RPLND between 1989 and 2010. Of 408 patients 330 had a NSGCT, 78 patients had a pure seminoma or a primary extragonadal germ cell cancer and were excluded from analysis. The tumour size at the time of surgery was available in 261 patients in the remaining 69 pateints no preopretive data with regard to the tumour size were recorded in the radiology reports. Due to the location of the residual tumour a median laparotomy, a thoracoabdominal approach was used. In one center a laparoscopic approach was preferred.

Results: Mean tumour diameter was 4.7 (0 to 32) cm. The patients were stratified in three groups: group 1 n=28 (RT<=1cm), group 2 n=23 (RT>1<=1.5cm) and group 3 n=209 (RT>1.5cm). The histological specimens contained teratoma in 21.4%, 39.1%, 44.5% respectively, viable cancer in 10.7%, 17.4% and 22% respectively, and fibrosis/necrosis in 64.3%, 52.2% and 37.8% respectively in the three grpups respectively.

Conclusions: The finding of both teratoma and viable cancer decreases with decreasing sizes of the residual tumour. Nevertheless lesions <= than 1 cm still harbour a significant pathohistology in one third of the patients. As a consequence PC-RPLND must not be omitted even in small RT.

No significant financial relationships to disclose.

Comparing the perioperative management of postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) in patients with pure seminomatous and nonseminomatous germ cell tumors (NSGCT)

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Background: PC-RPLND is a potentially complicated intervention. By the time the rate of complications and adjunctive surgery increased. Only few data are available concerning PC-RPLND in patients with advanced seminomas and residual retroperitoneal tumour lesions. We examined the intra and postoperative complications as well as the frequency of adjunctive surgeries in patients with seminoma and compared the data to a cohort of patients with NSGCT who underwent PC-RPLND.

Methods: In our multicenter retrospective analyses 408 patients underwent PC-RPLND between 1989 and 2010. 47 patients with advanced seminomas and 327 patients with NSGCT. The surgical approach was preferred via a midline incision or a thoracoabdominal approach due to the location of the residual tumour. In one center a laparoscopic approach was preferred.

Results: Of the 47 patients with seminoma a total number of 18 adjunctive surgeries were performed in 11 patients (8 nephrectomies, 3 inferior v.cava resections, 3 resections of the abdominal aorta, 2 resections of the colon, one nerv and 2 hepatic resections/biopsies). There was only one major intraoperative complication, injury of the v. cava and two postoperative complications, (prolonged intestinal paralyses). There were no significant differences adjunctive surgeries and postoperative complications (p=0.48 and p=0.133). There were significantly less intraoperative complications in favour of seminomas (p=0.006).

Conclusions: PCRLND in seminomas and NSGCT is a demanding surgical intervention. In contrast to other series we did not find significant differences in the two patient groups concerning adjunctive surgeries and postoperative complications. The indication for PCLND in patients with seminoma is limited, but if necessary it can be performed safely in experienced centers.

No significant financial relationships to disclose.