Use of ibandronate in the prevention of skeletal events in metastatic breast cancer

Deciphering molecular mechanisms of metastasis: novel insights into targets and therapeutics

BACKGROUND

The transition of a primary tumour to metastatic progression is driven by dynamic molecular changes, including genetic and epigenetic alterations. The metastatic cascade involves bidirectional interactions among extracellular and intracellular components leading to disintegration of cellular junctions, cytoskeleton reorganization and epithelial to mesenchymal transition. These events promote metastasis by reprogramming the primary cancer cell's molecular framework, enabling them to cause local invasion, anchorage-independent survival, cell death and immune resistance, extravasation and colonization of distant organs. Metastasis follows a site-specific pattern that is still poorly understood at the molecular level. Although various drugs have been tested clinically across different metastatic cancer types, it has remained difficult to develop efficacious therapeutics due to complex molecular layers involved in metastasis as well as experimental limitations.

CONCLUSIONS

In this review, a systemic evaluation of the molecular mechanisms of metastasis is outlined and the potential molecular components and their status as therapeutic targets and the associated pre-clinical and clinical agents available or under investigations are discussed. Integrative methods like pan-cancer data analysis, which can provide clinical insights into both targets and treatment decisions and help in the identification of crucial components driving metastasis such as mutational profiles, gene signatures, associated pathways, site specificities and disease-gene phenotypes, are discussed. A multi-level data integration of the metastasis signatures across multiple primary and metastatic cancer types may facilitate the development of precision medicine and open up new opportunities for future therapies.

[Bisphosphonate-associated osteonecrosis of the jaw]

BACKGROUND

Bisphosphonates (BP) are used in the treatment of severe osteoporosis and metastasis of malignant diseases. A possible relationship between the occurrence of osteonecrosis of the jaw and BP therapy was first described in 2003. Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is difficult to treat. In some cases the condition of the patients is so compromised that only minimally invasive surgery is possible. Histopathologically, osteonecrosis shows the features of chronic sequestered osteomyelitis, which can be found in different areas of the upper and lower jaw. Sometimes extensive resections of the jaw are necessary. Thus, BRONJ can cause mutilation, impairment of function and esthetics in the orofacial system and, thereby, compromise the life quality of the patients. Triggering factors are often tooth extraction without surgical plastic wound closure of the alveoli, but can also be associated with bruises from denture or other minor wounds.

OBJECTIVES

The purpose of this article is to present results from our own patient collective, including therapy regime, success rate, and therapy recommendations.

METHODS

The patient populations at three German hospitals were analyzed using a standard questionnaire. The patients in the study group, entered into a follow-up system for early detection of possible BRONJ, were evaluated for treatement outcome.

RESULTS

The success rate for prophylactic surgery in asymptomatic patients was very high at 96 %. In the group with symptomatic BRONJ, the outcome was significantly lower (76.4 %).

CONCLUSIONS

Because of the complex symptoms, close cooperation between oncologists, dentists, and maxillofacial surgeons is required in the treatment of BRONJ. Before starting therapy with bisphosphonates and during the therapy, dental treatment and monitoring of the patient' oral health is necessary.

Crosstalk between bone niche and immune system: osteoimmunology signaling as a potential target for cancer treatment

There is a well recognized link between the bone and the immune system and in recent years there has been a major effort to elucidate the multiple functions of the molecules expressed in both bone and immune cells. Several molecules that were initially identified and studied in the immune system have been shown to have essential functions also in the bone. An interdisciplinary field embracing immune and bone biology has been brought together and called "osteoimmunology". The co-regulation of the skeletal and immune systems strikingly exemplifies the extreme complexity of such an interaction. Their interdependency must be considered in designing therapeutic approaches for either of the two systems. In other words, it is necessary to think of the osteoimmune system as a complex physiological unit. Denosumab was originally introduced to specifically target bone resorption, but it is now under evaluation for its effect on the long term immune response. Similarly, our current and still growing knowledge of the intimate link between the immune system and bone will be beneficial for the safety of drugs targeting either of these integrated systems. Given the large number of molecules exerting functions on both the skeletal and immune systems, osteoimmunological understanding is becoming increasingly important. Both bone and immune systems are frequently disrupted in cancer; and they may be crucial in regulating tumor growth and progression. Some therapies - such as bisphosphonates and receptor activator of NF-κB ligand (RANKL) targeted drugs - that aim at reducing pathologic osteolysis in cancer may interact with the immune system, thus providing potential favorable effects on survival.

Interaction between the skeletal and immune systems in cancer: mechanisms and clinical implications

The skeletal and immune systems have a complex relationship. Both systems are intimately coupled, with osteoclastogenesis and hematopoiesis occurring in the bone marrow. Bone and immune cells also share common hematopoietic precursors. Furthermore, the skeletal and immune systems share various cytokines, receptors, and transcription factors that regulate signal transduction pathways involved in osteoclastogenesis and immune system activation, including the receptor activator of nuclear factor-κΒ ligand/receptor activator of nuclear factor-κΒ/osteoprotegerin (RANKL-RANK-OPG) pathway. Cancer cells can disrupt both the skeletal and immune systems. Interaction between cancer and bone cells results in a vicious cycle of bone destruction and cancer growth. Bone remodeling generates a growth-factor-rich environment that attracts cancer cells and promotes their proliferation. In turn, cancer cells stimulate osteoclast formation and activity, resulting in additional bone resorption that further stimulates cancer cell growth. Currently available bone-targeted therapies may also modulate the immune system. Bisphosphonates such as zoledronic acid exert stimulating effects on the immune system, resulting in possible anticancer activity against malignant cells. Denosumab, an anti-RANKL monoclonal antibody with proven antiosteoclast activity, may suppress immune responses. This may result in the reported association with an increased risk of neoplasms, as well as serious skin and other infections as reported in some studies, mainly in the postmenopausal setting. When assessing bone-targeted therapies, it is important to consider the shared signaling pathways between bone and the immune system, as well as the clinical risk:benefit ratio.