Ethan+Hazel

Ethan Hazel Biol 179: Cancer Biology Professor Andre Islas

**Raging Against the Dying of the Light: ** ** A Brief History of One Girl's Battle with Alveolar Rhabdomyosarcoma ** Emma Greer was a musician, an artist, and a popular social media personality on Twitter, Instagram, and the short-form video sharing service Vine. She gained the adoration of thousands through her candor, her bravery, and her unshakable optimism throughout the course of her treatment for alveolar rhabdomyosarcoma. Her social media presence became a living document of one individual’s journey through one of the most painful and terrifying experiences a human being can undergo. It was far from bleak, however. Rather, her legacy was one of grace, humor, and unwavering courage in the face of abject cruelty of circumstance. By all accounts, Emma was a beautiful human being who brought joy to all those with whom she i nteracted, becoming an inspiration for countless fans worldwide that were deeply affected by her strength and positivity.

Figure 1. Emma Greer. (1) In December 2013, Emma began to experience sharp pains in her stomach after eating. Knowing that there were any number of potential causes for her symptoms, most of them entirely benign, her parents decided to wait to see if the problem would go away naturally before bringing her to the doctor. Eventually, the pain became constant and Emma was brought to a physician to be examined. Unfortunately, it was not until weeks later when her stomach became distended and extremely painful that she was taken to the hospital at UNC Chapel Hill. Because Emma’s symptoms were consistent with a patient’s immune response to abdominal tumors, she was brought to the cancer center at UNCCH. There, it was determined that her stomach was swollen with fluid being produced to combat the cancer cells present in her abdominal muscles. This fluid was putting a severe amount of pressure on her organs, causing the intense pain. After six liters of fluid were drained from her 90 pound frame, Emma was finally diagnosed with Stage IV alveolar rhabdomyosarcoma. Her cancer had progressed to the point where her abdominal muscles were completely covered in small tumors. Furthermore, though it had originated in the abdominal muscles, by the point it was discovered it had metastasized into her bone tissue.

Rhabdomyosarcoma, a malignant tumor that arises in skeletal muscle cells (2), is the most common soft tissue cancer in individuals under the age of 21 in the United States (3). Nonetheless, it is still very rare, with only 350 cases being diagnosed each year in minors and only 400 adult cases in the last 25 years (2). Only one child in ten diagnosed with rhabdomyosarcoma has a clear genetic risk factor associated with development of RMS (2), and no such genetic syndromes were identified in Emma. Similar to the vast majority of children who develop RMS, Emma’s cancer was the result of sheer chance.

Alveolar rhabdomyosarcoma is the more aggressive of the two types of RMS – the other is embryonal rhabdomyosarcoma (3). Race and gender have both been demonstrated to be non-factors in RMS risk or prognosis (3), but the survival rate for children diagnosed with RMS decreases with age (4). While the disease-free survival rate five years following diagnosis is 81% for children diagnosed between the ages of one and nine, it drops to 68% for Emma’s age bracket of children ten or older (5). The more unfavorable prognosis for adolescents is due to higher rates of metastasis and alveolar histology, characterized by the way that an abundance of small tumors covers the muscle tissue and gives it an appearance similar to the alveoli of a human lung (5). Both were factors in Emma’s own poor prognosis. Due to the late, Stage IV diagnosis and the alveolar histology of Emma’s RMS, the doctors were not optimistic about her chances of failure free survival. She was given months to live.

Emma’s physicians decided to start Emma on a chemotherapy regimen that is normally consistent with week 7 of a yearlong sequence of treatments. Chemotherapy is never a pleasant process, but without a gradual intensification of treatment, it becomes positively torturous. Emma experienced pain that few teenagers are ever forced to endure, but did so with stoic determination and stubborn optimism. Contrary to all expectations, Emma’s RMS responded to chemotherapy. In December 2014, she was declared cancer free after almost a year of intensive treatment. Unfortunately, her period of remission was brief. Emma’s cancer returned just four months later. Once again, she was given weeks to months to live, and once again she defied expectations. By all appearances through sheer power of will and pugnacious positivity, she made it almost another entire year before finally succumbing to the disease.

Figure 2. Emma after starting chemotherapy. (1)  ** The Molecular Basis of Rhabdomyosarcoma ** Alveolar rhabdomyosarcoma is caused by a chromosomal translocation wherein parts of two nonhomologous chromosomes are rearranged. In 80% of ARMS cases, a translocation between two chromosomes causes a fusion of two otherwise separate genes (6). One of the fused genes, Pax3, codes for a DNA transcription activator, PAX3, which is important for muscle fiber development in the embryo. The other gene, Fkhr, codes for a molecule responsible for the regulation of the aging process and myogenesis, the process by which muscle tissue forms. Fkhr-Fkhr, the fusion gene produced, is an oncogene, meaning that it has the ability to transform an otherwise normal cell into a tumor cell.

Figure 3. Rhabdomyosarcoma in muscle tissue. (7) Rhabdomyosarcomas occur in the skeletal muscle, and the tumors that develop tend to undergo myogenesis. Because human myogenesis primarily occurs during fetal development, the vast majority of RMS patients are children (8). In Emma’s case, the cancer originated in the cells of her abdominal muscle. These cells were mutated to carry the fusion gene //Pax3-Fkhr//, which results in the synthesis of themutant protein PAX3-FKHR. This protein is a transcriptional activator that has signific ant oncogenic properties.PAX3-FKHR binds to the same target domain as a wildtype PAX3 protein, but is a far more potent activator of the myogenesis growth pathway (9).

Though PAX3-FKHR binds to the same DNA region as PAX3, and activates the same myogenesis pathway, it lacks a domain present in PAX3 that allows for an inhibitory protein to bind and halt transcription when cell growth is no longer beneficial to the organism (10). In this way, the //Pax3-Fkhr// fusion gene ensures the continuation of the cell cycle by signaling the cell to continue growth and division when it would otherwise be signaled to stop growing (8).

Figure 4. The //Pax3-Fkhr// fusion gene. (11) Alveolar rhabdomyosarcoma is predominantly characterized by two of Hanahan and Weinberg’s ‘Hallmarks of Cancer,’ self-sufficiency in growth signals and insensitivity to anti-growth signals (12). Due to the increased transcriptional activity of PAX3-FKHR, the mutated cells receive internal signals to grow and divide at a greatly increased rate when compared to wildtype cells containing the PAX3 protein. Furthermore, because the mutant protein lacks the domain that would receive inhibitory signals to stop growth, the cells avoid the normal process by which the cell cycle would be halted before replication if the DNA were damaged.

Alveolar rhabdomyosarcoma is also particularly prone to metastasis, likely due to a high level of vascularization in the tumor cells. ARMS is able to aggressively proliferate to other tissues because of a process known as vasculogenic mimicry, wherein the vascular network surrounding the tumor cells develop a structure resembling that of endothelial cells, which line the surface of blood vessels (13). In this way, tumor cells are able to rapidly generate vascular tissue without undergoing true angiogenesis, wherein new blood vessels are developed (14). When combined with normal levels of angiogenesis, which occurs simultaneously, vasculogenic mimicry allows ARMS to metastasize at a higher rate than other forms of cancer. Emma’s cancer spread quickly from her muscle cells to her bone tissue and was able to effectively colonize to form secondary tumors. From there, the cancer cells rapidly proliferated throughout her body.

Figure 5. Vasculogenic mimicry. (15)  ** Treating Alveolar Rhabdomyosarcoma ** Upon diagnosis, almost all patients with alveolar rhabdomyosarcoma are treated with surgery to remove tumors and surrounding tissue in an attempt to prevent metastasis. The treating physicians only choose to forego surgery when the tumors are too large, too abundant, or the cancer has already metastasized. By the time Emma was diagnosed, the cancer was already in stage IV; it had metastasized to the bone tissue. Since surgery was deemed an ineffective course of treatment, other options had to be considered.

The traditional therapies in this case are radiation and chemotherapy, which would have been necessary with or without surgery. The purpose of radiation therapy is to damage the DNA of the cancer cells to the point at which they can no longer replicate, regardless of any mutations that allowed them to proliferate uncontrollably in the first place. The cells will cease division and eventually die (16). Since Emma’s cancer was too delocalized to irradiate completely without causing irreparable DNA damage to her healthy cells, chemotherapy was the only traditional treatment option. Traditional chemotherapy drugs target cells undergoing rapid division, allowing for specificity. Cancer cells are poisoned while most other cells, aside from those in quickly dividing tissues such as bone marrow, hair follicles, and the intestinal lining, are left alone. The general chemical cocktail used in RMS chemotherapy is a combination of vincristine and dactinomycin (17). This was the chemo regimen that Emma was put on, starting at a dose that would normally be given to patients on week seven of a year-long treatment cycle.

Though Emma was not treated with any targeted therapy, there are a number of targeted treatments being developed for use on RMS. The two most promising novel drugs being tested are cixutumumab, an IGF-1 receptor inhibitor, and bevacizumab, which prevents tumors from vascularizing (18). IGF-1 is a growth factor that triggers cell proliferation (19). IGF-1 receptor inhibitors, such as cixutumumab, bind to a cell’s IGF-1 receptor and prevent IGF-1 from activating the growth pathway. In this way, cixutumumab can halt the growth of cancer cells without harming any healthy cells. Phase II trials for the efficacy of cixutumumab at preventing tumor growth have shown that it is broadly effective in rhabdomyosarcoma patients with limited adverse effects. (20). Bevacizumab prevents angiogenesis, the growth of new blood vessels in tumor cells through the inhibition of VEGF-A, a cancer-specific growth factor that triggers vascularization (21). It has been demonstrated in rodents to significantly decrease microvessel density surrounding rhabdomyosarcoma tumors, particularly when employed in conjunction with radiation therapy (22).

Figure 6. Bevacizumab inhibiting the VEGF pathway. (23) If Emma had been diagnosed earlier, bevacizumab could have been a potent treatment ideal for preventing metastasis. Because Emma’s RMS exhibited vascular mimicry, a phenomenon associated with vascular signaling pathways, including VEGF, it seems likely that bevacizumab, a VEGF inhibitor, could have arrested angiogenesis in her abdominal cancer cells before her RMS metastasized to her bone tissue (24). Given that Emma’s cancer had already metastasized to her bone marrow by the time of diagnosis, however, cixutumumab would have been the more effective course of these two targeted therapies. Emma’s RMS was characterized by the //Pax3-Fkhr// fusion gene, which has been demonstrated to be a transactivator of the IGF-1 growth pathway (25). Cixutumumab, an IGF-1 receptor inhibitor, could have prevented the transactivation of the IGF-1 pathway and thereby halted cell growth in the affected tissues while traditional chemotherapy treatments were applied to destroy the remaining cancer cells. Though both of these therapies could potentially have been effective on Emma’s cancer, neither has yet been approved for rhabdomyosarcoma treatment and so neither was available for Emma. ** Conclusion ** Figure 7. Emma Greer. Emma Greer passed away on March 27, 2016 after a battle with cancer lasting over two years. She was 16 years old. In her short time on this Earth, she managed to touch the lives of everyone she encountered both in person and through social media. Though she was just sixteen years old when she died, she left a more lasting legacy than many who live to be many times her age. Alveolar rhabdomyosarcoma is an insidious disease that tragically takes children too soon, leaving families broken and loved ones grieving. There is hope, however, in the new treatments being researched and developed. Perhaps soon, boys and girls like Emma will not be forced to endure the grueling, drawn out, and ultimately ineffective treatment regimen as Emma. Regardless of the medical progress that is made in the near future, Emma’s influence on young people dealing with serious or terminal illnesses is and will remain immense.

** Apercu ** Alveolar rhabdomyosarcoma is a very serious disease, but it is not a death sentence. If diagnosed early enough, its growth can be arrested and the diseased cells can be annihilated before metastasizing. The future is looking more and more optimistic for patients suffering from ARMS, with new targeted therapies being developed to stop the disease in its tracks and route it from the patient’s body without the excessive side effects that come with traditional treatments.

** References ** (1) Greer, Emma. @emgreerie. //Twitter//. .

(2) Wexler, Leonard H., M.D. "Rhabdomyosarcoma." Liddy Shriver Sarcoma Initiative. Liddy Shriver Sarcoma Initiative. Web. 19 Apr. 2016. .

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(7) Figure 3. .

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(9) Fredericks, William J., et al. (1995). "The PAX3-FKHR fusion protein created by the t (2; 13) translocation in alveolar rhabdomyosarcomas is a more potent transcriptional activator than PAX3." Molecular and Cellular Biology 15.3:1522-1535. 

(10) Lam, Paula YP, et al. (1999). "The oncogenic potential of the Pax3-FKHR fusion protein requires the Pax3 homeodomain recognition helix but not the Pax3 paired-box DNA binding domain." Molecular and cellular biology 19.1: 594-601. 

(11) Figure 4. .

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(15) Figure 5. <https://www.researchgate.net/figure/225290866_fig4_Schematic-representation-of-CSC-participation-in-vasculogenic-mimicry-and>.

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(19) Laviola, Luigi, Annalisa Natalicchio, and Francesco Giorgino. (2007). "The IGF-I signaling pathway." Current pharmaceutical design 13.7: 663-669. <http://www.ingentaconnect.com/content/ben/cpd/2007/00000013/00000007/art00002>.

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(23) Figure 6. <http://www.avastin-hcp.com/about-avastin/proposed-moa>.

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