Pathophysiology and treatment of pain in multiple myeloma

Abstract

Most patients with multiple myeloma (MM) suffer from chronic pain of varying degrees of intensity at every stage of the natural disease process. Osteolytic bone lesions are one of the most common complications of MM. The bone disease visualized by PET/CT and MRI affects up to 90% of newly diagnosed MM patients, increasing the risk of the development of skeletal-related events. Pathological fractures and spinal cord compression occur in 17% and 6% of patients, respectively. Bone pain is explained by an increase in pressure in the bone marrow, the release of chemical mediators by myeloma plasma cells, and the occurrence of microcracks in the bones, indirectly to a violation of local metabolism. Management of myeloma bone disease includes anti-myeloma chemotherapy and radiotherapy, antiresorptive therapy with bisphosphonates or denosumab, and direct pharmacological pain correction. Patients with pathological vertebral fractures and without spinal cord compression should be considered for vertebroplasty or kyphoplasty. The use of proteasome inhibitors and monoclonal antibodies for the treatment of MM is associated with a risk of herpes simplex virus (HSV) and varicella-zoster virus (VZV) reactivation. The result of the healing of herpetic eruptions in some patients will be the development of postherpetic neuralgia, manifested by excruciating pain for months or years. Moreover, the treatment with proteasome inhibitor bortezomib is often associated with the development of long-term persistent peripheral neuropathy, often complicated by pain. According to their neurobiological and clinical features, pain is classified into nociceptive, neuropathic, and functional. Bone pain is nociceptive and for postherpetic and chemotherapy-induced neuropathy, the neuropathic component is more significant. Opioids are the drugs of choice for moderate to severe nociceptive pain, while anticonvulsants and antidepressants are the most commonly used adjuvants for neuropathic pain. This review summarizes information on the pathophysiology of various types of pain syndrome in patients with MM, as well as on modern approaches to the prevention and treatment of complications. The issues of the pharmacology of opioid analgesics are discussed. The review concludes with data from a clinical trial of a new domestic non-opioid μ1-opioid receptor agonist Tafalgin, considered a real alternative to narcotic analgesics.