Neuroblastoma Response to Therapy Trumps Age

In April of 2013, we received a tissue sample from investigators in Victoria, Espirito Santo, Brazil. The pediatric oncologist involved requested assistance in the management of a four-year-old child with Stage IV (metastatic) neuroblastoma.

The patient was originally diagnosed in February with abdominal pain and a tumor. The tumor was identified by ultrasound as a large left-sided retroperitoneal mass. The patient was treated with the combination of doxorubicin plus cyclophosphamide. Within a month, it was evident that his “high risk neuroblastoma” would require stronger chemotherapy. Doses were adjusted upward and cisplatin was added. As the patient’s tumor infiltrated his bone marrow, his tolerance of chemotherapy became limited. By early June, after recovering from severe infectious complications, with no evidence of response to treatment, he was taken to surgery.

For background, neuroblastoma is the third most common malignancy of childhood. It arises from sympathetic ganglia (nerve cells) and presents in different forms. It has long been recognized that these tumors can be driven by an up-regulation of the oncogene MYCN. Children above the age of 1.5 years and those with wide dissemination are at highest risk.

We received this patient’s tissue and immediately isolated the malignant populations. As the tumor is only identified in children, it was a somewhat unusual occurrence for our laboratory. In addition, the patient had already received extremely aggressive treatment without benefit. We chose among the drugs that we considered potentially active for study and proceeded with our analysis.

The EVA-PCD assay results were highly instructive. First, those drugs that the patient had already received (platins, alkylating agents) were clearly inactive. Second, the signal transduction inhibitors like imatinib, and everolimus were also inactive. What was striking however, was the extraordinary degree of sensitivity to taxol that placed this patient among the most sensitive patients we have ever tested. The profile for taxol also extended to two taxol-based combinations: taxol plus platinum and taxol plus gemcitabine. However neither combination revealed significant synergy, suggesting that taxol was the principally active agent.

biology.arizona.edu

As I considered our laboratory findings in the context of the contemporary pediatric neuroblastoma literature, several interesting threads emerged. The first, was that investigators in Leiden, Netherlands had described a microtubule associated protein (MAP) encoded double cortin-like kinase gene (DCLK1) in neuroblastoma patients.  The second was the very early but promising work using aurora kinase inhibitors in this disease. It became evident that these observations had their nexus at microtubule function. In keeping with the adult literature this would clearly support classes of drugs that induce G2-M arrest in the cell cycle. I reasoned that the taxanes were highly appropriate for this child based both on our findings and these related molecular correlates.

We contacted the physician in Brazil, and recommended a taxol-based treatment program. It became evident that neither taxol, nor the related carboplatin plus taxol or taxol plus gemcitabine regimens, were in this pediatric oncologist’s lexicon for neuroblastoma. Our report included references to clinical trials in adult tumors where these combinations have been broadly applied. However, it was going to require a certain amount of creative thinking for this well-trained pediatric oncologist to cross walk our “adult” recommendations to this child in need. Fortunately, with the assistance from our collaborators in Sao Paolo, the physician agreed to use our combination in this child who was failing standard treatment.

The results were prompt and dramatic. Within a single cycle of therapy, virtually all symptoms resolved. The child began to eat well and gain weight and despite chemotherapy, the bone marrow function rapidly recovered and the blood counts normalized. With completion of two cycles, a repeat CT scan revealed complete resolution of measurable disease.

I have corresponded with the pediatric oncologist and expressed our delight with the outcome and of her willingness to work with us. This case represents not only a transnational collaboration (the subject of a recent ASCO presentation) but also the successful cross-fertilization between the pediatric and adult oncology specialties. We are deeply gratified on both accounts.

The Tumor Micro Environment

As I was reading the October 1 issue of the Journal of Clinical Oncology, past the pages of advertisement by gene profiling companies, I came upon an article of very real interest.

While most scientists continue to focus on cancer-gene analyses, a report in this issue from a collaboration between American and European investigators provided compelling evidence for the role of tumor associated inflammatory cells in metastatic human cancer. (Asgharzadeh, S J Clin Oncol 30 (28)3525–3532 Oct 1, 2012) Through the analysis of children with metastatic neuroblastoma, they found that the degree of infiltration into the tumor environment by macrophages had a profound effect upon clinical outcome. This study confirmed earlier reports that macrophage infiltration is an integral part and potential driver of the malignant process.

Using immunohistochemistry and light microscopy the investigators scored patients for the number of CD163(+) macrophages, representing the alternatively activated (M2) subset within the tumor tissue. They then examined inflammation related gene expressions to develop a “high” risk, “low” risk algorithm and applied it to the progression free survival in these children.

Highly significant differences were observed between the two groups. This report adds to a growing body of literature that describes the interplay between cancer cells and their microenvironment. Similar studies in breast cancer, melanoma and multiple myeloma have shown that tumor cells “co-opt” their non-malignant counterparts as they drive transformation from benign to malignant, from in-situ to invasive and from localized disease to metastatic. These same forces have the potential to strongly influence cellular responses to stressors like chemotherapy and growth factor withdrawal. While we may now be on the verge of identifying these tumor attributes and characterizing their impact upon survival, these analyses represent little more than increasingly sophisticated prognostics.

The task at hand remains the elucidation of those attributes and features that characterize each patient’s tumor response to injury toward ultimate therapeutic response. To address this level of complexity, we need the guidance of more global measures of human tumor biology, measures that incorporate the dynamic interplay between tumors cells, their stroma, vasculature and the inflammatory environment.  These are the “real-time” insights that can only be achieved using human tissue in its native state. Ex vivo analyses offer these insights. Their information moves us from the realm of prognostics to one of predictives, and it is after all predictive measures that our patients are most desperately in need of today.