How to maintain patients on long-term therapy: understanding the profile and kinetics of adverse events

[Chemotherapy-induced peripheral neuropathy: Symptomatology and epidemiology]

Chemotherapy-induced peripheral neuropathy (CIPN) is common with specific semiological characteristics. When CIPN appears, there are many difficulties in guaranteeing sustained treatment, especially with optimal protocol. Moreover, CIPN have bad repercussions on quality of life after cancer disease. In this article, we have achieved a current state of CIPN and try to report details about semiological characteristics and topography. We have also produced some epidemiological data. Nonetheless, we have not voluntarily introduced treatment because it will be the topic of further work.

Long-Term Effects, Pathophysiological Mechanisms, and Risk Factors of Chemotherapy-Induced Peripheral Neuropathies: A Comprehensive Literature Review

Neurotoxic anticancer drugs, such as platinum-based anticancer drugs, taxanes, vinca alkaloids, and proteasome/angiogenesis inhibitors are responsible for chemotherapy-induced peripheral neuropathy (CIPN). The health consequences of CIPN remain worrying as it is associated with several comorbidities and affects a specific population of patients already impacted by cancer, a strong driver for declines in older adults. The purpose of this review is to present a comprehensive overview of the long-term effects of CIPN in cancer patients and survivors. Pathophysiological mechanisms and risk factors are also presented. Neurotoxic mechanisms leading to CIPNs are not yet fully understood but involve neuronopathy and/or axonopathy, mainly associated with DNA damage, oxidative stress, mitochondria toxicity, and ion channel remodeling in the neurons of the peripheral nervous system. Classical symptoms of CIPNs are peripheral neuropathy with a “stocking and glove” distribution characterized by sensory loss, paresthesia, dysesthesia and numbness, sometimes associated with neuropathic pain in the most serious cases. Several risk factors can promote CIPN as a function of the anticancer drug considered, such as cumulative dose, treatment duration, history of neuropathy, combination of therapies and genetic polymorphisms. CIPNs are frequent in cancer patients with an overall incidence of approximately 38% (possibly up to 90% of patients treated with oxaliplatin). Finally, the long-term reversibility of these CIPNs remain questionable, notably in the case of platinum-based anticancer drugs and taxanes, for which CIPN may last several years after the end of anticancer chemotherapies. These long-term effects are associated with comorbidities such as depression, insomnia, falls and decreases of health-related quality of life in cancer patients and survivors. However, it is noteworthy that these long-term effects remain poorly studied, and only limited data are available such as in the case of bortezomib and thalidomide-induced peripheral neuropathy.

Proteasome inhibitors in AL amyloidosis: focus on mechanism of action and clinical activity

Proteasome inhibitors are the backbone in the treatment of multiple myeloma with 3 of its representatives (bortezomib, carfilzomib, and ixazomib) having already been approved. There is a different situation altogether in the treatment of amyloid light chain (AL) amyloidosis where owing to the rarity of this entity neither of these drugs has currently gained approval. Amyloid light chain plasma cells are possibly more vulnerable to bortezomib than myeloma plasmocytes because of a slightly distinct mechanism of action, which is described in depth in this manuscript. Bortezomib is highly active and rapidly effective as a single agent and even more potent in combination with dexamethasone and alkylators. Bortezomib-based regimens have become a standard part of the initial treatment of AL amyloidosis in the majority of centers. We have reviewed all available data on bortezomib in various combinations and settings. Carfilzomib seems to be effective but also toxic in these fragile patients with a high rate of cardiac events. Oral ixazomib has shown a surprisingly high efficacy with manageable toxicity and has received the Food and Drug Administration Breakthrough Therapy designation in 2014 for relapsed AL amyloidosis patients. In this review we have comprehensively described the current available knowledge of these 3 proteasome inhibitors and their use in AL amyloidosis.

Physiologically-based pharmacokinetic modeling of target-mediated drug disposition of bortezomib in mice

Bortezomib is a reversible proteasome inhibitor with potent antineoplastic activity that exhibits dose- and time-dependent pharmacokinetics (PK). Proteasome-mediated bortezomib disposition is proposed as the primary source of its nonlinear and apparent nonstationary PK behavior. Single intravenous (IV) doses of bortezomib (0.25 and 1 mg/kg) were administrated to BALB/c mice, with blood and tissue samples obtained over 144 h, which were analyzed by LC/MS/MS. A physiologically based pharmacokinetic (PBPK) model incorporating tissue drug-target binding was developed to test the hypothesis of proteasome-mediated bortezomib disposition. The final model reasonably captured bortezomib plasma and tissue PK profiles, and parameters were estimated with good precision. The rank-order of model estimated tissue target density correlated well with experimentally measured proteasome concentrations reported in the literature, supporting the hypothesis that binding to proteasome influences bortezomib disposition. The PBPK model was further scaled-up to humans to assess the similarity of bortezomib disposition among species. Human plasma bortezomib PK profiles following multiple IV dosing (1.3 mg/m(2)) on days 1, 4, 8, and 11 were simulated by appropriately scaling estimated mouse parameters. Simulated and observed bortezomib concentrations after multiple dosing were in good agreement, suggesting target-mediated bortezomib disposition is likely for both mice and humans. Furthermore, the model predicts that renal impairment should exert minimal influence on bortezomib exposure in humans, confirming that bortezomib dose adjustment is not necessary for patients with renal impairment.

Treatment for patients with newly diagnosed multiple myeloma in 2015

Multiple myeloma is the second most frequent haematological disease. The introduction of high-dose melphalan followed by autologous haematopoietic cell transplant (HDT/ASCT) for young patients and the availability of novel agents for young and elderly patients with multiple myeloma have dramatically changed the perspective of treatment. However, further research is necessary if we want to definitively cure the disease. Treatment goals for transplant-eligible and non-transplant-eligible patients should be to prolong survival by achieving the best possible response, while ensuring quality of life. The treatment should be individualized on the basis of host and disease features and better monitoring of the response upon use of high-sensitivity techniques for evaluating residual disease. For young patients, HDT/ASCT is a standard of care for treatment and its efficacy has been enhanced and challenged by the new drugs. For elderly patients, treatment options were limited to alkylators, but new upfront treatment combinations based on novel agents (proteasome inhibitors and immunomodulatory drugs) combined or not with alkylators have significantly improved outcomes.Extended treatment for young and elderly patients improves the quality and duration of clinical responses; however,the optimal scheme, appropriate doses and duration of long-term therapy have not yet been fully determined.This review summarises the progress in the treatment of patients with newly diagnosed multiple myeloma, addressing critical questions such as the optimal induction, early versus late ASCT, consolidation and/or maintenance for young patients, and how we can choose the best option for non-transplant-eligible patients.

The emerging role of carfilzomib combination therapy in the management of multiple myeloma

Carfilzomib is a proteasome inhibitor that selectively and irreversibly binds to its target, resulting in sustained inhibition absent of off-target effects relative to bortezomib. Single-agent carfilzomib has produced robust and durable responses in clinical trials and it has been approved in the US for treating relapsed and refractory multiple myeloma (MM). Due to its favorable safety profile, carfilzomib is particularly suitable for use in combination strategies. Promising data have been reported from studies that investigated the use of carfilzomib in combination with immunomodulators, alkylating agents, glucocorticoids, histone deacetylase inhibitors and kinesin spindle protein inhibitors. Ongoing pivotal randomized Phase III studies are investigating the efficacy and safety of carfilzomib combinations in patients with relapsed MM and transplant ineligible patients.

Initial treatment of transplant-ineligible patients in multiple myeloma

Over two-thirds of newly diagnosed multiple myeloma are over 65 years. The treatment goals for the non-transplant-eligible patients should be to prolong survival by achieving the best response, while ensuring quality of life. New upfront treatment combinations based on first generation of novel proteasome inhibitors and immunomodulatory drugs plus alkylating agents, the historical platform, have significantly improved outcomes in the past 10 years. Other non-alkylator induction regimens, essentially lenalidomide plus low-dose dexamethasone are also available and provide a novel backbone that may be combined with novel second- and third-generation drugs. Data indicate that prolonged treatment extends the progression-free survival. In summary, this group requires individualized and dose-modified regimens to improve tolerability and efficacy, while maintaining their quality of life.

How should we treat newly diagnosed multiple myeloma patients?

Multiple myeloma (MM) is the second most frequent hematological disease. Two-thirds of newly diagnosed MM patients are more than 65 years of age. Elsewhere in this issue, McCarthy et al discuss the treatment of transplantation candidates; this chapter focuses on the data available concerning therapy for non-transplantation-eligible MM patients. Treatment goals for these non-transplantation-eligible patients should be to prolong survival by achieving the best possible response while ensuring quality of life. Until recently, treatment options were limited to alkylators, but new up-front treatment combinations based on novel agents (proteasome inhibitors and immunomodulatory drugs) plus alkylating agents have significantly improved outcomes. Other nonalkylator induction regimens are also available and provide a novel backbone that may be combined with novel second- and third-generation drugs. Phase 3 data indicate that maintenance therapy or prolonged treatment in elderly patients also improves the quality and duration of clinical responses, extending time to progression and progression-free survival; however, the optimal scheme, appropriate doses, and duration of long-term therapy have not yet been fully determined. The potential for novel treatment regimens to improve the adverse prognosis associated with high-risk cytogenetic profiles also requires further research. In summary, although we have probably doubled the survival of elderly patients, this group requires close monitoring and individualized, dose-modified regimens to improve tolerability and treatment efficacy while maintaining their quality of life.