Current Phase II investigational proteasome inhibitors for the treatment of multiple myeloma

How I treat fragile myeloma patients

Multiple myeloma is a disease typical of elderly people, with a median age at diagnosis of 70 years. Much progress has been made in the past few years thanks to the introduction of new drugs. However, increases in survival were much less pronounced in patients aged 60 to 69 years, and no improvement was seen in older patients. Furthermore, the currently approved treatment regimens were tested in clinical trials with stringent inclusion criteria. Aging is associated with a high prevalence of frailty, that is, a state of increased vulnerability to stressors due to a critical decline in physiologic reserves. Elderly people may be categorized as fit or frail according to clinical, functional, cognitive, and socioeconomic criteria. The presence of frailty may complicate the management and outcome of myeloma patients. To date, the choice of treatment of myeloma patients has focused primarily on chronological age and performance status as markers of frailty. However, the elderly population is highly heterogeneous, and improved assessment strategies are needed to define the frailty profile of patients and provide them with the most adequate treatment, thus avoiding the overtreatment of frail patients and the undertreatment of fit patients. The geriatric assessment is a fundamental tool for the evaluation of cognitive and functional status.

Recent advances and future directions in targeting the secretory apparatus in multiple myeloma

Multiple myeloma is a genetically heterogeneous tumour of transformed plasma cells, terminally differentiated effectors of the B cell lineage specialized in producing large amounts of immunoglobulins. The uniquely well-developed secretory apparatus that equips normal and transformed plasma cells with the capacity for high-level protein secretion constitutes a distinctive therapeutic target. In this review we discuss how fundamental cellular processes, such as the unfolded protein response (UPR), endoplasmic reticulum (ER)-associated degradation and autophagy, maintain intracellular protein homeostasis (proteostasis) and regulate plasma cell ontogeny and malignancy. We summarize our current understanding of the cellular effects of proteasome inhibitors and the molecular bases of resistance to them. Furthermore, we discuss how improvements in our understanding of the secretory apparatus and of the complex interactions between intracellular protein synthesis and degradation pathways can disclose novel drug targets for multiple myeloma, defining a paradigm of general interest for cancer biology and disorders of altered proteostasis.