Harmonization of criteria and terminology in fetal rat skeletal evaluations

BACKGROUND

A survey of laboratories in North American and Europe that routinely conduct fetal skeletal examinations was performed with the purpose of (1) understanding current terminology used for classifying skeletal findings in developmental toxicity (DT) studies and (2) understanding the criteria used to identify relatively common findings that sufficiently deviate from normal. The goal was to promote terminology harmonization and improve interlaboratory consistency in the criteria used to identify developmental anomalies.

METHODS

The survey, designed based on terminology for developmental anomalies recommended by an international collaboration (Makris et al., Congenital Anomalies, 2009;49(3):123-246), was conducted by a subgroup (authors of this publication) of the Royal Society of Biology's International Register of Fetal Morphologists (IRFM).

RESULTS

Individual and summarized anonymized responses are provided here. The authors, who are expert fetal morphologists with experience performing fetal examinations, reviewed the responses and generated recommendations on preferred terminology and criteria for determining when morphological variations deviate from normal and warrant recording of the findings for skeletal observations in Sprague Dawley (SD) fetal rats. The objective of these recommendations is to complement Makris et al. (Congenital Anomalies, 2009;49(3):123-246).

CONCLUSION

The broad application will improve interlaboratory harmonization of recording fetal skeleton findings in developmental toxicity studies intended for regulatory submissions, including SEND (Standard for Exchange of Nonclinical Data).

Negative hyper-selection of metastatic colorectal cancer patients for anti-EGFR monoclonal antibodies: the PRESSING case-control study

Background

Refining the selection of metastatic colorectal cancer patients candidates for anti-epidermal growth factor receptor (EGFR) monoclonal antibodies beyond RAS and BRAF testing is a challenge of precision oncology. Several uncommon genomic mechanisms of primary resistance, leading to activation of tyrosine kinase receptors other than EGFR or downstream signalling pathways, have been suggested by preclinical and retrospective studies.

Patients and methods

We conducted this multicentre, prospective, case-control study to demonstrate the negative predictive impact of a panel of rare genomic alterations [PRESSING (PRimary rESiStance IN RAS and BRAF wild-type metastatic colorectal cancer patients treated with anti-eGfr monoclonal antibodies) panel], including HER2/MET amplifications, ALK/ROS1/NTRK1-3/RET fusions and PIK3CA mutations. Hypothesizing a prevalence of candidate alterations of 15% and 0% in resistant and sensitive RAS and BRAF wild-type patients, respectively, with two-sided α and β errors of 0.05 and 0.20, 47 patients per group were needed.

Results

Forty-seven patients per group were included. PRESSING panel alterations were significantly more frequent in resistant (24 out of 47, 51.1%) than in sensitive (1 out of 47, 2.1%) patients (P < 0.001) and in right- (12 out of 29, 41.4%) than left-sided (13 out of 65, 20.0%) tumours (P = 0.03). The predictive accuracy of PRESSING panel and sidedness was 75.3% and 70.2%, respectively. Among hyper-selected patients, right-sidedness was still associated with resistance (P = 0.002). The predictive accuracy of the combined evaluation of PRESSING panel and sidedness was 80.4%. As a secondary analysis, 8 (17.0%) resistant and 0 sensitive patients showed microsatellite instability (P < 0.001).

Conclusion

The investigated panel of genomic alterations allows refining the selection of RAS and BRAF wild-type metastatic colorectal cancer patients candidates for anti-EGFRs, partially explaining and further corroborating the predictive ability of primary tumour sidedness.

Abstract P2-02-19: Circulating tumor DNA detection anticipates disease recurrence in early stage breast cancer: A pilot study generating an observational confirmatory trial

Sensitive tumor biomarkers able to monitor disease progression would contribute to post-surgical treatment decision making in early breast cancer. We investigated the feasibility of using circulating tumor DNA (ctDNA) to early detect new disease manifestations in serial plasma samples collected during post-surgery follow-up from patients operated for stage I breast cancer from 1992 to 1993 at Istituto Nazionale Tumori in Milan. Forty patients that underwent radical or conservative surgery for T1/T2-N0-M0 breast cancer and that were followed for at least 15 years were included in a pilot study for the retrospective analysis of ctDNA on at least 3 plasma samples obtained during follow-up. To assess the feasibility of ctDNA analysis in archival plasma samples collected in heparin and stored from 10 to 25 years, preliminary experiments demonstrated that ctDNA was not affected by: 1) heparinase I digestion of extracted DNA and 2) DNA pre-amplification step to overcome limitations due to small plasma aliquots. Mutational analysis of breast cancer tissues was performed by Ion Torrent-targeted next generation sequencing and the identified Single Nucleotide Variations (SNV) were first validated and then tracked in plasma samples by using ad hoc digital polymerase chain reaction assays. One or more SNVs were identified in tumor tissue specimens and validated in 27/40 cases. Among those 27 breast cancers, 6 cases relapsed locally, 4 in distant sites, and 17 remained disease-free for the entire follow-up. ctDNA was undetectable during the post-surgical follow-up in 16/17 disease-free women up to 160 months of surgery, while it was detectable in 9/10 patients developing unfavorable events and anticipated the clinical diagnosis of relapse in 7/10 patients with a median lead time of 20 months. Our results are the first to associate mutation tracking to local recurrence and indicate that in patients with early breast cancer ctDNA monitoring during post-operative follow-up can anticipate the diagnosis of new disease manifestations, thus potentially allowing prompt treatments. These findings establish the rational to plan prospective studies to evaluate in the early breast cancer context the potential of ctDNA as a non-invasive and sensitive biomarker for monitoring tumor progression. Based on these results, we activated in 2016 a prospective observational study to confirm the predictive value of ctDNA on local and distant relapse in patients with early and localized triple negative breast cancer. As for May 2017, 145 patients with triple negative tumors were potentially enrolled for a ctDNA-based post-surgical follow-up: 111 cases at first diagnosis and 34 cases at surgery after neo-adjuvant treatment. One hundred-ten women accepted to participate in the study and signed a specific informed consent, whereas 22 patients refused to participate and 13 were lost to follow-up. For 94 patients (66 at initial diagnosis and 28 after neoadjuvant chemotherapy) plasma samples have been already longitudinally collected and DNA sequencing is currently in progress.

Citation Format: Daidone MG, Di Cosimo S, Veneroni S, Cascone F, De Cecco L, Dugo M, Folli S, Bianchi GV, Tamborini E, Busico A, Appierto V. Circulating tumor DNA detection anticipates disease recurrence in early stage breast cancer: A pilot study generating an observational confirmatory trial [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-02-19.

Best practices for the management of local-regional recurrent chordoma: a position paper by the Chordoma Global Consensus Group

Chordomas are rare, malignant bone tumors of the skull-base and axial skeleton. Until recently, there was no consensus among experts regarding appropriate clinical management of chordoma, resulting in inconsistent care and suboptimal outcomes for many patients. To address this shortcoming, the European Society of Medical Oncology (ESMO) and the Chordoma Foundation, the global chordoma patient advocacy group, convened a multi-disciplinary group of chordoma specialists to define by consensus evidence-based best practices for the optimal approach to chordoma. In January 2015, the first recommendations of this group were published, covering the management of primary and metastatic chordomas. Additional evidence and further discussion were needed to develop recommendations about the management of local-regional failures. Thus, ESMO and CF convened a second consensus group meeting in November 2015 to address the treatment of locally relapsed chordoma. This meeting involved over 60 specialists from Europe, the United States and Japan with expertise in treatment of patients with chordoma. The consensus achieved during that meeting is the subject of the present publication and complements the recommendations of the first position paper.

BRAF codons 594 and 596 mutations identify a new molecular subtype of metastatic colorectal cancer at favorable prognosis

BACKGROUND

While the negative prognostic role of BRAF V600E mutation in metastatic colorectal cancer (mCRC) is well established, the impact of BRAF codons 594 and 596 mutations, occurring in <1% of CRCs, is completely unknown. The present work aims to describe clinical, pathological and molecular features and prognosis of BRAF codons 594 and 596 mutant mCRCs, compared with BRAF V600E mutant and wild-type ones.

PATIENTS AND METHODS

Patients treated for mCRC at three Italian Institutions between October 2006 and October 2014, with available KRAS and NRAS codon 12, 13, 59, 61, 117 and 146 and BRAF codon 594, 596 and 600 mutational status, as detected by means of direct sequencing or matrix assisted laser desorption ionization time-of-flight MassArray, were included.

RESULTS

Ten patients bearing BRAF codons 594 or 596 mutated tumors were identified and compared with 77 and 542 patients bearing BRAF V600E mutated and BRAF wild-type tumors, respectively. While BRAF V600E mutated tumors were more frequently right-sided, mucinous and with peritoneal spread, BRAF 594 or 596 mutated were more frequently rectal, nonmucinous and with no peritoneal spread. All BRAF 594 or 596 mutated tumors were microsatellite stable. Patients with BRAF codons 594 or 596 mutated tumors had markedly longer overall survival (OS) when compared with BRAF V600E mutated [median OS: 62.0 versus 12.6 months; hazard ratio: 0.36 (95% confidence interval 0.20-0.64), P = 0.002], both at univariate and multivariate analyses.

CONCLUSIONS

BRAF codon 594 or 596 mutated mCRCs are different from BRAF V600E ones in terms of molecular features, pathological characteristics and clinical outcome. This is consistent with preclinical evidences of a kinase inactivating effect of these mutations. The role of CRAF in transducing the intracellular signal downstream BRAF 594 or 596 mutated proteins opens the way to further preclinical investigation.

PD-L1 marks a subset of melanomas with a shorter overall survival and distinct genetic and morphological characteristics

BACKGROUND

Programmed cell death ligand 1 (PD-L1) is a cell surface molecule that plays a critical role in suppressing immune responses, mainly through binding of the PD-1 receptor on T lymphocytes. PD-L1 may be expressed by metastatic melanoma (MM). However, its clinical and biological significance remains unclear. Here, we investigated whether expression of PD-L1 in MM identifies a biologically more aggressive form of the disease, carrying prognostic relevance.

PATIENTS AND METHODS

PD-L1 expression was analyzed by immunohistochemistry using two different antibodies in primary tumors and paired metastases from 81 melanoma patients treated at a single institution. Protein expression levels were correlated with PD-L1 mRNA, BRAF mutational status and clinical outcome. PD-L1(+) and PD-L1(-) subsets of the A375 cell line were stabilized in vitro and compared using gene expression profiling and functional assays. Results were confirmed using xenograft models.

RESULTS

PD-L1 membrane positivity was detected in 30/81 (37%) of patients. By multivariate analysis, Breslow thickness and PD-L1 membrane positivity were independent risk factors for melanoma-specific death {PD-L1 5% cutoff [hazard ratio (HR) 3.92, confidence interval (CI) 95% 1.61-9.55 P < 0.003], PD-L1 as continuous variable (HR 1.03, 95% CI 1.02-1.04 P < 0.002)}. PD-L1 expression defined a subset of the BRAF-mutated A375 cell line characterized by a highly invasive phenotype and by enhanced ability to grow in xenograft models.

CONCLUSIONS

PD-L1 is an independent prognostic marker in melanoma. If confirmed, our clinical and experimental data suggest that PD-L1(+) melanomas should be considered a disease subset with distinct genetic and morpho-phenotypic features, leading to enhanced aggressiveness and invasiveness.

Activity of temozolomide in patients with advanced chemorefractory colorectal cancer and MGMT promoter methylation

BACKGROUND

No evidence-based treatment options are available for patients with advanced colorectal cancer (CRC) progressing after standard therapies. MGMT is involved in repair of DNA damage and MGMT promoter methylation may predict benefit from alkylating agents such as temozolomide. The aim of our study was to evaluate the activity of temozolomide in terms of response rate in patients with metastatic CRC and MGMT methylation, after failure of approved treatments.

PATIENTS AND METHODS

Patients were enrolled in a monocentre, open-label, phase II study and treated with temozolomide at a dose of 150 mg/m2/day for 5 consecutive days in 4-weekly cycles. The treatment was continued for at least six cycles or until progressive disease.

RESULTS

Thirty-two patients were enrolled from August 2012 to July 2013. Treatment was well tolerated with one grade 4 thrombocytopenia and no other grade≥3 toxicities. No complete response occurred. The objective response rate was 12%, reaching the pre-specified level for promising activity. Median progression-free survival and overall survival were 1.8 and 8.4 months, respectively. Patients with KRAS, BRAF and NRAS wild-type CRC showed significantly higher response when compared with those with any RAS or BRAF mutation (44% versus 0%; P=0.004). TP53 status had no influence on the primary end point.

CONCLUSIONS

Temozolomide is tolerable and active in heavily pre-treated patients with advanced CRC and MGMT promoter methylation. Further studies in biomolecularly enriched populations or in a randomized setting are necessary to demonstrate the efficacy of temozolomide after failure of standard treatments.

Mode of action of trabectedin in myxoid liposarcomas

To elucidate the mechanisms behind the high sensitivity of myxoid/round cell liposarcoma (MRCL) to trabectedin and the suggested selectivity for specific subtypes, we have developed and characterized three MRCL xenografts, namely ML017, ML015 and ML004 differing for the break point of the fusion gene FUS-CHOP, respectively of type I, II and III. FUS-CHOP binding to the promoters of some target genes such as Pentraxin 3 or Fibronectin 1, assessed by chromatin immunoprecipitation, was strongly reduced in the tumor 24 h after the first or the third weekly dose of trabectedin, indicating that the drug at therapeutic doses causes a detachment of the FUS-CHOP chimera from its target promoters as previously shown in vitro. Moreover, the higher sensitivity of MRCL types I and II appears to be related to a more prolonged block of the transactivating activity of the fusion protein. Doxorubicin did not affect the binding of FUS-CHOP to target promoters. Histologically, the response to trabectedin in ML017 and ML015 was associated with a marked depletion of non-lipogenic tumoral cells and vascular component, as well as lipidic maturation as confirmed by PPARγ2 expression in western Blot. By contrast, in ML004 no major changes either in the cellularity or in the amount of mature were found, and consistently PPARγ2 was null. In conclusion, the data support the view that the selective mechanism of action of trabectedin in MRCL is specific and related to its ability to cause a functional inactivation of the oncogenic chimera with consequent derepression of the adypocytic differentiation.

Phase II study on lapatinib in advanced EGFR-positive chordoma

BACKGROUND

To report on a prospective, investigator-driven, phase II study on lapatinib in epidermal growth factor receptor (EGFR)-positive advanced chordoma patients.

PATIENTS AND METHODS

From December 2009 to January 2012, 18 advanced progressing chordoma patients entered this study (median age: 61 years; disease extent: metastatic 72% and locally advanced 28%). Epidermal growth factor receptor (EGFR) expression and activation were evaluated by immunohistochemistry and/or phospho-arrays, real-time polimerase chain reaction, fluorescence immunostaining. Fluorescence in situ hybridization analysis was also carried out. Patients received lapatinib 1500 mg/day (mean dose intensity = 1282 mg/day), until progression or toxicity. The primary study end point was response rate (RR) as per Choi criteria. Secondary end points were RR by Response Evaluation Criteria in Solid Tumor (RECIST), overall survival, progression-free survival (PFS) and clinical benefit rate (CBR; RECIST complete response + partial response (PR) + stable disease (SD) ≥ 6 months).

RESULTS

All patients were evaluable for response. Six (33.3%) patients had PR and 7 (38.9%) SD, as their best Choi responses, corresponding to RECIST SD in all cases. Median PFS by Choi was 6 [interquartile (IQ) range 3-8] months. Median PFS by RECIST was 8 (IQ range 4-12) months, with a 22% CBR.

CONCLUSIONS

This phase II study showed a modest antitumor activity of lapatinib in chordoma. The clinical exploitation of EGFR targeting in chordoma needs to be further investigated, both clinically and preclinically. Clinical trial Registration No: EU Clinical Trials Register trial no. 2009-014456-29.

Multiangle static and dynamic light scattering in the intermediate scattering angle range

We describe a light scattering apparatus based on a novel optical scheme covering the scattering angle range 0.5° ≤ θ ≤ 25°, an intermediate regime at the frontier between wide angle and small angle setups that is difficult to access by existing instruments. Our apparatus uses standard, readily available optomechanical components. Thanks to the use of a charge-coupled device detector, both static and dynamic light scattering can be performed simultaneously at several scattering angles. We demonstrate the capabilities of our apparatus by measuring the scattering profile of a variety of samples and the Brownian dynamics of a dilute colloidal suspension.

Phase II clinical trial of neoadjuvant trabectedin in patients with advanced localized myxoid liposarcoma

BACKGROUND

To evaluate neoadjuvant trabectedin (1.5 mg/m(2) 24-h i.v. infusion every 3 weeks; three to six cycles) in patients with locally advanced myoxid liposarcoma (ML) previously untreated with chemotherapy or radiation.

PATIENTS AND METHODS

Primary efficacy end point was pathological complete response (pCR) or tumoral regression rate. Objective response according to RECIST (v.1.0) was a secondary end point.

RESULTS

Three of 23 assessable patients had pCR [13%; 95% confidence interval (CI), 3% to 34%]. Furthermore, very good and moderate histological responses were observed in another 2 and 10 patients, respectively. Histological decrement in the cellular and vascular tumor component and maturation of tumor cells to lipoblasts were observed in both myoxid and myoxid/round cell variants. Seven patients had partial response according to RECIST (objective response rate of 24%; 95% CI, 10% to 44%). No disease progression was reported. Neoadjuvant trabectedin was usually well tolerated, with a safety profile similar to that described in patients with soft tissue sarcoma or other tumor types.

CONCLUSION

Trabectedin 1.5 mg/m(2) given as a 24-h i.v. infusion every 3 weeks is a therapeutic option in the neoadjuvant setting of ML.

Role of EGFR family receptors in proliferation of squamous carcinoma cells induced by wound healing fluids of head and neck cancer patients

BACKGROUND

Mounting evidence suggests that recurrence of resected head and neck squamous cell carcinomas (HNSCCs) is due to the outgrowth of unrecognized residual tumor cells as well as to the premalignant and/or precursor-field epithelial cells. We studied the impact of processes triggered by HNSCC surgery in stimulating both residual tumor cells [demonstrated to overexpress epidermal growth factor receptor (EGFR)], and premalignant cells surrounding the resected lesion.

PATIENTS AND METHODS

EGFR expression/activation by immunohistochemistry/biochemistry and gene status by FISH were investigated in 23 primary HNSCCs and surrounding tissues. The ability to induce cell proliferation of wound healing drainages collected from 12 relapsed and 11 not relapsed patients was evaluated by a colorimetric assay in squamous cell carcinoma cell lines A431 (carrying EGFR amplification) and CAL27 (carrying three EGFR copies) in the presence/absence of EGFR therapeutic inhibitors.

RESULTS

Primary tumors showed intermediate/high EGFR expression (91%), EGFR phosphorylation and EGFR-positive FISH (35%). Normal, metaplastic and dysplastic epithelium surrounding the resected tumor displayed EGFR overexpression. EGFR activation and gene amplification were observed in normal and dysplastic epithelium, respectively. Each tested wound healing drainage induced the cells to proliferate and the proliferation was significantly higher in relapsed compared with not relapsed HNSCC patients (P = 0.02 and P = 0.03). Anti-EGFR treatments inhibited the drainage-induced proliferation, with the highest inhibitory efficiency by cetuximab on A431 cells, while CAL27 cell growth was more efficiently inhibited by tyrosine kinase inhibitors.

CONCLUSIONS

Surgery could favor the proliferation of cells showing EGFR overexpression/activation/amplification such as residual tumor cells and/or precursor-field epithelial cells already present after surgery. Treatment with anti-EGFR reagents inhibits wound-induced stimulation, according to the EGFR family status.

Post-imatinib surgery in advanced/metastatic GIST: is it worthwhile in all patients?

BACKGROUND

Surgical indication for metastatic gastrointestinal stromal tumor (GIST) treated with imatinib is not yet established.

MATERIALS AND METHODS

We analyzed 80 patients who underwent surgery for metastatic GIST after imatinib therapy from July 2002 to October 2007. Patients were divided into those with surgery at best clinical response (group A, n = 49) and those with surgery at focal progression (group B, n = 31). Primary end points were progression-free survival (PFS) and disease-specific survival (DSS).

RESULTS

Two-year postoperative PFS was 64.4% in group A and 9.7% in group B (P < 0.01). In group A, median PFS was not reached; in group B, it was 8 months. Median DSS from the time of imatinib onset was not reached in either group. Five-year DSS was 82.9% in group A and 67.6% in group B (P < 0.01). Multivariate analysis confirmed a significantly shorter PFS and DSS in group B. Surgical morbidity occurred in 13 patients (16.3%).

CONCLUSIONS

Surgery for focal progressive lesions could be considered as part of the second-line/third-line armamentarium in selected cases. Surgery of residual disease upon best clinical response seems associated with survival benefit compared with historical controls in similar patient collectives treated with imatinib alone. However, evidence from prospective randomized trials is needed to make definite recommendations.

Response to imatinib plus sirolimus in advanced chordoma

BACKGROUND

Imatinib (IM) is active in advanced chordoma. The evidence of upstream and/or downstream mammalian target of rapamycin (mTOR) pathway activation prompted us to combine an mTOR inhibitor, sirolimus, to IM in IM-resistant advanced chordoma.

PATIENTS AND METHODS

Since July 2007, 10 progressive advanced chordoma patients with secondary resistance to IM, and biochemical and/or immunohistochemical evidence of upstream and/or downstream mTOR effector activation, started IM (400 mg/day) plus sirolimus (2 mg/day) on a named basis.

RESULTS

The mean treatment duration was 9 months. Of nine patients assessable for response, at 3 months, we had one RECIST partial response (PR), seven stable disease (SD) and one progressive disease (PD). According to Choi criteria applied even to magnetic resonance imaging, we had seven PR (> or =10% decrease in size in four cases), one SD and one PD. Seven patients had a positron emission tomography response. The clinical benefit [RECIST complete response + PR + SD > or =6 months] was 89%. Pretreatment mTOR effectors analysis carried out in nine cases was positive in all patients (AKT activation in six patients, S6Sp6 expression/activation in seven). Post-treatment biopsy in one responsive patient confirmed S6 switch off.

CONCLUSION

In addition to PDGFRB, mTOR pathway can be activated in chordomas and the combination of IM plus rapalogs may be effective in IM-resistant chordomas.

Oncogenic and ligand-dependent activation of KIT/PDGFRA in surgical samples of imatinib-treated gastrointestinal stromal tumours (GISTs)

As the range of receptor tyrosine kinase (RTK) inhibitors widens, a detailed understanding of the activating mechanisms of KIT/platelet-derived growth factor receptor (PDGFR)A and the related downstream pathways involved in the development and maintenance of GISTs is becoming increasingly important. We analysed areas with different histological response ratios in surgical specimens taken from imatinib-treated and untreated GIST patients in order to investigate KIT and PDGFRA expression/activation, the presence of their cognate ligands and the activation of downstream signalling, by means of biochemistry, immunohistochemistry and flow cytometry. All of the cases showed KIT and PDGFRA co-expression. In addition to the oncogenic activation of mutated receptors, activation of wild-type KIT and wild-type PDGFRA, sustained by heterodimerization and an autocrine-paracrine loop, was demonstrated by the presence of their specific ligands, stem cell factor (SCF) and PDGFA. To confirm RTK activation further, all of the samples (including those with the highest regression ratios) were investigated for downstream effectors, and all proved to have activated downstream signalling. The results show that after the mutated receptors are switched off, heterologous wild-type receptors become important in imatinib-treated GISTs as a means of maintaining signalling activation. Taken together, our findings suggest that drugs targeting wild-type receptors should be tested in imatinib-treated GIST patients.

Preoperative imatinib mesylate for unresectable or locally advanced primary gastrointestinal stromal tumors (GIST)

AIM

To explore the effect of preoperative imatinib mesylate (IM) in patients with unresectable or locally advanced primary gastrointestinal stromal tumor (GIST).

METHODS

From January 2003 to January 2008, all patients affected by bulky localized GIST who presented at our institution were considered for preoperative IM with cytoreductive intent. Clinical, pathological and molecular characteristics were assessed and the rate of response recorded. Progression-free survival (PFS) was calculated according to Kaplan-Meier analysis.

RESULTS

Fifteen patients (1 esophageal, 7 gastric, 3 duodenal, 4 rectal GISTs) received preoperative IM for a median of 9 months. All patients had tumor shrinkage, with a median size reduction of 34%. One patient had radiological complete response. In all cases an improvement of the originally planned surgical procedure was obtained: 3 patients initially considered unresectable underwent complete surgery; 7 patients with initial indication for extensive surgery were more conservatively operated on; 4 patients initially deemed at high perioperative risk underwent safe surgery. Due to the small sample size, no association between tumor shrinkage and tumor site, size, IM duration, mutational status and pathological response could be formally explored. PFS at 3 years from IM onset was 77%.

CONCLUSIONS

In unresectable or locally advanced GISTs, preoperative IM is a useful tool both to improve resectability and reduce surgical morbidity. It should be therefore always be considered before embarking on a major surgical procedure. The long-term impact of IM on PFS and survival is presently under investigation in multicenter prospective randomized trials.

Imatinib mesylate in advanced chordoma: A multicenter phase II study

10003

Background: The antitumor activity of Imatinib in chordoma was preliminarily shown in a compassionate series of 18 pts. This prospective Phase II collaborative study was planned thereafter. Methods: From November 2004 to April 2006, 55 pts with progressing advanced chordoma were enrolled in this Phase II study. Cases were provided by 13 Italian centers and one Swiss. Imatinib was given at the planned dose of 800 mg/day (for a received dose intensity in excess of 600 mg/day), until evidence of progression. Mean age was 59 yrs, (range 24–86); PS 0–3 (=2 in 22%); site of origin was the sacrum in 60%, spine in 25%, skull base in 15%; the disease was metastatic in 43% and localized advanced in 57%. All tumors were positive for PDGFRB/PDGFB. Results: In 44 pts evaluable for antitumor response, 37 (84%) had stable disease as their best RECIST response, which was maintained for more than 6 months in 32, for a clinical benefit rate (CR+PR+SD=6mos) of 73%. In 7 of these SD pts (16%), a degree of objective tumor shrinkage was reported. Centralized radiological review is underway, focusing on non-dimensional, “tissue” response, and results thereof will be presented. In 39 pts who were symptomatic at baseline, subjective improvement of symptoms was claimed by 25 (64%). On ITT analysis, median PFS was 32 wks, with 38% of pts free from progression at one year, and 16% on treatment at 18 months. Most frequent drug-related adverse events were nausea (35%) and vomiting (30%), edema (30%), skin rash (28%), G1–3 anemia (24%), asthenia (17%), G1–3 leucopenia (13%). Conclusions: Preliminary evidence of Imatinib efficacy in chordoma was provided in a single-institution, compassionate setting, and is now confirmed by this multicenter Phase II study. On the basis of these data, an international effort on molecular-targeted therapy with Imatinib in advanced chordoma is warranted.

No significant financial relationships to disclose.

Adding cisplatin (CDDP) to imatinib (IM) re-establishes tumor response following secondary resistance to IM in advanced chordoma

10038

Background: IM is active in advanced chordoma, possibly by targeting PDGFRB. Secondary progressions following response have been observed. The case of a pt with sacral chordoma and lung adenocarcinoma responding to CDDP soon after stopping IM prompted us to combine the two drugs in IM-resistant advanced chordoma. Methods: Since February 2006, 6 advanced chordoma pts (F=4, M=2; mean age 56 yrs; PS 0–2) with a secondary resistance to IM following previous response, have started IM 400 mg/day + low-dose CDDP (25 mg/sqm/wk) on an individual use basis. Results: One pt completed her treatment (after 7 mos, reaching a total dose of CDDP = 525 mg/sqm), and, following ablation of the residual lesion, is now continuing on IM alone. The remaining pts are on combination therapy (4 for <2 mos). After 4–6 weeks, 4 pts had a PET response (SUV max decrease ≥25%), with subjective improvement and stable disease on CT/MRI, while 2 were metabolically stable. In the 2 pts treated for >12 weeks, a minor dimensional response was observed after 3 mos. The single pt who completed combination therapy had a continuous PET scan improvement throughout treatment, and pre-ablation biopsy of residual tumor showed histological signs of tumor response (marked cellular depletion and sclerohyalinosis in most of the sample, with residual tumor cells intermingled with inflammatory ones). Conclusions: In 4 out of 6 advanced chordoma pts progressing on IM, a tumor response was re-established by adding CDDP, and 2 pts treated for a relatively longer interval showed dimensional tumor shrinkage. Four more pts are starting therapy, and results will be updated. An independent cytotoxic effect of CDDP cannot be ruled out, but sensitivity of chordoma to CDDP is at best occasional. The combination of IM and CDDP may have synergic activity in chordoma.

[Table: see text]

Perioperative morbidity in metastatic gastrointestinal stromal tumors (GIST) undergoing surgery of residual disease following imatinib (IM)

10043

Background: To review the morbidity of post-IM surgery of residual disease in a consecutive series of metastatic, IM- sensitive, GIST pts. Methods: Between November 2002 and September 2006, 29 pts with metastatic GIST were operated on, being progression- free on IM for at least 6 months. Median preoperative IM duration was 17 mos. Only patients deemed to be completely resectable on CT/MRI were considered for surgery. Major surgical procedures were generally excluded. Results: Surgery consisted in explorative laparotomy with resection of residual visible disease, omentectomy in 13 cases, intestinal resections in 10, minor hepatic resections in 7, radiofrequency ablations of liver nodules in 2, spleno-pancreatectomy in 2. Macroscopically complete surgery could be performed in 90% of pts. Median operative time was 180’ (range 120–420). Median post-surgery discharge time was 9 days (range 4–35). Median preoperative Hb level was 12.2 mg/dL and the median perioperative whole blood and fresh frozen plasma units required was 1.5 and 2.9 (range 0–16 and 0–44), respectively. In 28% of pts, there was post-operative ascites (daily peritoneal effusion of >200 ml), which generally responded to medical therapy in one week. Postoperative levels of AST/ALT reached twice the baseline in 48% of pts, independently of whether liver resections had been carried out. Postoperative pneumonia was observed in 38% of patients. Major surgical complications occurred in 14% (one bleeding, one evisceration, and two anastomotic leakages). After a median follow up of 36 mos from surgery, PFS was 69% at 2 yrs (65% at 4 yrs from IM-onset). Conclusions: While this was a series of favorably selected patients, and major surgical procedures were preferably avoided, surgical perioperative morbidity turned out to be higher than expected. This reinforces the view that post-IM surgery of residual disease in metastatic GIST pts should be considered investigational, as long as its efficacy in improving prognosis is not demonstrated.

[Table: see text]

Analysis of potential receptor tyrosine kinase targets in intimal and mural sarcomas

Primary sarcomas of the great vessels are very rare neoplasms and only a few cases have been reported. They are divided into the two broad categories of intimal or luminal and mural sarcomas. We analysed eight advanced high-grade sarcomas originating from major vessels (seven intimal and one mural sarcoma) by means of immunohistochemistry and FISH analysis for PDGFRA, PDGFRB, EGFR and KIT receptor tyrosine kinases (RTKs), together with immunoprecipitation/western blotting, sequencing of the corresponding genes, and the search for cognate ligands. The intimal sarcomas showed a wide spectrum of morphologies and immunophenotypes, whereas the mural sarcoma had common leiomyosarcomatous features. Regardless of their category, all of the cases had a PDGFRA-deregulated cytogenetic profile mainly consisting of an amplification cluster; five were also polysomic for PDGFRB, whereas three showed disomy. Six cases had a deregulated EGFR gene, and c-Kit gene status was similar to that of PDGFRA. In one case, biochemical analysis revealed the presence of activated and highly expressed PDGFRA, PDGFRB and EGFR, whereas KIT was expressed at reference level. Sequencing of the corresponding genes revealed no activating mutations in any of the analysed receptors. The cognate ligands were detected in all cases. In predictive terms, the evidence of gene amplification/high polysomy of several RTKs, together with PDGFRA, PDGFRB and EGFR expression and phosphorylation, suggests that these tumours may be sensitive to RTK-inhibiting treatments.

Detection of novel mRNA splice variants of human ING4 tumor suppressor gene

Inhibitor of growth (ING)4, member of a gene family encoding potential tumor suppressors, is implicated as a repressor of angiogenesis and tumor growth and suppresses loss of contact inhibition in vitro. Here, we report that ING4 undergoes alternative splicing. Expression analysis identified novel ING4 spliced variant mRNAs encoding proteins devoid of different portions. The ING4 variants were detected in both normal and tumor tissues. The existence of ING4 variants was confirmed by several approaches, including reverse transcriptase-polymerase chain reaction, real-time PCR and in silico experiments. To investigate the functional consequences of alternative splicing the ING4 variant cDNAs were expressed in mammalian cells. Our studies indicated that (i) the ING4 variants do not differ from wild-type in their nuclear localization, interaction with p53 and association to HBO1 complex; and (ii) the ING4-DeltaEx6A variant, devoid of the C-terminal portion, loses the capability to inhibit NF-kappaB. On the whole our data suggest that alternative splicing could modulate the activity of ING4 tumor suppressor protein.

Functional analyses and molecular modeling of two c-Kit mutations responsible for imatinib secondary resistance in GIST patients

Imatinib-acquired resistance related to the presence of secondary point mutations has become a frequent event in gastrointestinal stromal tumors. Here, transient transfection experiments with plasmids carrying two different KIT-acquired point mutations were performed along with immunoprecipitation of total protein extracts, derived from imatinib-treated and untreated cells. The molecular mechanics/Poisson Boltzmann surface area computational techniques were applied to study the interactions of the wild-type and mutated receptors with imatinib at the molecular level. Biochemical analyses showed KIT phosphorylation in cells transfected with vectors carrying the specific mutant genes. Imatinib treatment demonstrated that T670I was insensitive to the drug at all the applied concentrations, whereas V654A was inhibited by 6 microM of imatinib. The modeling of the mutated receptors revealed that both substitutions affect imatinib-binding site, but to a different extent: T670I substantially modifies the binding pocket, whereas V654A induces only relatively confined structural changes. We demonstrated that T670I and V654A cause indeed imatinib-acquired resistance and that the former is more resistant to imatinib than the latter. The application of molecular simulations allowed us to quantify the interactions between the mutated receptors and imatinib, and to propose a molecular rationale for this type of drug resistance.

PDGFRα, PDGFRβ and KIT expression/activation in conventional chondrosarcoma

Chondrosarcomas represent 20% of all primary bone sarcomas, and many studies have attempted to unravel molecular targets for future development of new therapies. The aim of this study was to investigate the expression/activation of PDGFRalpha, PDGFRbeta and KIT receptor tyrosine kinases (RTKs) as potential therapeutic targets in conventional central primary chondrosarcomas (CCS). The expression of PDGFRalpha, PDGFRbeta and KIT RTKs was detected in 16 CCSs using immunohistochemistry (IHC), and their level of expression and activation status were analysed by immunoprecipitation and western blot experiments. PDGFRalpha, PDGFRbeta and KIT cDNAs were screened to verify the presence of activating mutations and the presence of the cognate ligands was analysed by means of RT-PCR. RTK gene amplification was further studied by means of fluorescence in situ hybridization (FISH) analysis. The immunophenotyping and biochemical analyses showed that the CCSs co-expressed PDGFRalpha and PDGFRbeta, with the latter showing definitively greater protein expression and phosphorylation levels. PDGFRbeta was expressed but not activated in control healthy joint cartilage, in line with no PDGFB detection. Conversely, the KIT gene product did not seem to play a relevant role. These findings, in the absence of activating mutations or an abnormal genomic profile and the presence of PDGFA and PDGFB expression, are consistent with an autocrine/paracrine loop activation of the corresponding receptors. The CCS gene profile described here offers a rationale for the use of RTK inhibitors alone or in combination with chemotherapy, and supports further investigation of RTKs and their downstream signals.

Gene expression profile identifies a rare epithelioid variant case of pleomorphic liposarcoma carrying FUS-CHOP transcript

AIMS

To describe a tumour with morphological and immunophenotypic characteristics of epithelioid variant of pleomorphic liposarcoma. Pleomorphic liposarcoma is a very rare variant of liposarcoma defined morphologically by the presence of pleomorphic lipoblasts showing peculiar epithelial-like features that can be confused with primary or metastatic carcinoma.

METHODS AND RESULTS

Molecular analysis demonstrated for the first time the presence of FUS-CHOP transcript in this liposarcoma variant. Microarray analysis revealed a gene expression profile related to a more aggressive tumour type when compared with other myxoid/round cell liposarcomas.

CONCLUSIONS

The present data show that the epithelioid variant of pleomorphic liposarcoma represents a further variant of myxoid liposarcoma sharing the FUS-CHOP fusion transcript but carrying a distinct expression profile, in keeping with its aggressive clinical course.