Neurological toxicity of long-term (>1 yr) thalidomide therapy in patients with multiple myeloma

New therapies in multiple myeloma

The melphalan-prednisone regimen has been considered as standard therapy for patients with multiple myeloma (MM) for many years. Recently, high-dose chemotherapy with stem-cell support has extended progression-free survival and increased overall survival, and it is now considered conventional therapy in younger patients. However, most patients relapse and the salvage treatment is not very effective. New active drugs, including immunomodulatory agents, thalidomide (Thal) and lenalidomide, and the proteasome inhibitor bortezomib, have shown promising anti-myeloma activity. These novel treatments are aimed at overcoming resistance of tumour cells to conventional chemotherapy, acting both directly on myeloma cells and indirectly by blocking the interactions of myeloma cells with their local microenvironment and suppressing growth and survival signals induced by autocrine and paracrine loops in the bone marrow. Thal has been widely studied, mostly in combination regimens in patients with relapsed MM and, more recently, in front-line therapy, showing efficacy in terms of response rate and event-free survival. Bortezomib has been found to possess remarkable activity, especially in combination with other chemotherapeutic agents, in relapsed/refractory and newly diagnosed MM, as well as in patients presenting adverse prognostic factors. Lenalidomide, in combination with dexamethasone, is showing high overall response rates in relapsed and refractory MM and promising results also in first-line therapy. In this paper, the results of the most significant trials with Thal, bortezomib and lenalidomide are reported. Several ongoing clinical studies will hopefully allow the identification of the most active combinations capable of improving survival in patients with MM.

Phase II trial of thalidomide for therapy of radioiodine-unresponsive and rapidly progressive thyroid carcinomas

BACKGROUND

There are no known effective therapies for distantly metastatic, rapidly progressive thyroid carcinomas unresponsive to radioiodine.

OBJECTIVE

Since thyroid carcinomas are hypervascular and thalidomide is antiangiogenic, we assessed thalidomide's tumoristatic effects and toxicity in a phase II trial.

DESIGN

Thirty-six patients with follicular, papillary, insular, or medullary thyroid carcinomas and distant, radioiodine-unresponsive metastases (volumes increasing >or= 30% per year before entry) were accrued between July 2001 and December 2002. Daily thalidomide started at 200 mg, increasing over 6 weeks to 800 mg or maximum tolerated dose. Toxicities and responses were assessed at 8-week intervals with tumor volume assessments.

MAIN OUTCOMES

Twenty-eight of 36 patients were evaluable, 5 with partial responses (PR: 18%; 95% confidence interval [95% CI]: 6-37%) and 9 patients with stable disease (SD: 32%; 95% CI: 12-42%) for overall 50% response (95% CI: 31-69%). Median PR duration was 4 months (range: 2-6 months), and SD duration was 6 months (range: 2-14 months). Median survival was 23.5 months for responders (PR + SD) and 11 months for nonresponders. Most frequent toxicity was fatigue (69% grade 1-2, 8% grade 3-4). Four patients had grade 3-4 infections (without neutropenia), one had pericardial effusion, and one had pulmonary embolus.

CONCLUSIONS

Thalidomide confers therapeutic benefit in subsets of thyroid cancer patients with rapidly progressive, distantly metastatic disease.

Thalidomide inhibits pentylenetetrazole-induced seizures

Thalidomide was originally synthesized and tested as a sedative, hypnotic and antiemetic; however, after its teratogenicity was noted its use for treatment of neurological and psychiatric disorders was abandoned. We studied the potential anticonvulsant effect of thalidomide: Different doses of thalidomide were tested against seizures induced by 50 mg/kg or 70 mg/kg of pentylenetetrazole (PTZ); the anticonvulsant effect of thalidomide was also compared with that of valproic acid. Seizures and latency time were individually recorded. Thalidomide in low doses (5-10 mg/kg) prevented seizures in all animals treated with 50 mg/kg PTZ; also, in a dose-dependent manner thalidomide inhibited seizures in rats exposed to a high dose of PTZ (70 mg/kg); thalidomide exhibited an anticonvulsant activity similar to that of valproic acid. Thalidomide is an effective anticonvulsant, and further studies on this potential antiepileptic substance seem warranted.

An analysis of clinical trials assessing the efficacy and safety of single-agent thalidomide in patients with relapsed or refractory multiple myeloma

Given that the efficacy/safety of thalidomide for relapsed or refractory multiple myeloma have not been well characterized in a randomized, controlled setting, an analysis of larger, single-agent trials was conducted. Nine trials met the following inclusion criteria: primary population of multiple myeloma; all patients relapsed or refractory; single-agent thalidomide; and sample size > or =50. At median doses of 200 - 800 mg per day, the pooled overall response rate (ORR) was 28.2% (95% CI: 22.6 - 33.7%), including a complete response (CR) rate of 1.6% (95% CI: 0.3 - 2.9%) and partial response rate of 26.0% (95% CI: 20.1 - 32.0%). Response was typically based on M-protein reduction alone. Peripheral neuropathy (PN) incidence varied from 12 - 44%, possibly impacted by the short median follow-up (9 - 29 months). Pooled venous thromboembolism (VTE) incidence was 2.7% (95% CI: 1.1 - 4.3%) and discontinuation due to intolerance (DDI) rate was 14.9% (95% CI: 12.0 - 17.7%). Overall survival (OS), progression-free survival (PFS) and PN incidence were not pooled due to lack of reporting and trial heterogeneity. Prognostic factors identified included B2M (PFS) and advanced age (PFS and OS). Overall, thalidomide demonstrated an ORR approaching 30%, with low CR rate of 1.6% and VTE and DDI incidences of 3% and 15%, respectively.

Management of Multiple Myeloma with Bortezomib: Experts Review the Data and Debate the Issues

Cure for multiple myeloma is rare; the success of treatment is measured by response, and length of remissions and survival. Initial treatment for patients young and fit enough is high-dose chemotherapy with autologous stem cell transplantation. Various chemotherapy regimens are employed as initial therapy in patients who cannot withstand the autologous stem cell transplantation regimen, and for treatment of refractory or relapsed disease. Commonly used agents either alone or in combination have included dexamethasone, vincristine, doxorubicin, melphalan, cyclophosphamide, etoposide, cisplatin and, more recently, thalidomide. Within the past few years, the first-in-class proteasome inhibitor bortezomib has been introduced for the treatment of relapsed multiple myeloma with data demonstrating efficacy and safety. Throughout Europe, a faculty of experts conducted a series of debates with over 450 clinicians to discuss the efficacy of bortezomib vis-à-vis other available therapies. Of primary concern was the place of bortezomib in maximizing efficacy throughout the course of the disease and treatment by increasing response rates and improving duration of response, while maintaining an acceptable level of toxicity. The experts concluded that bortezomib, with its unique mechanism of action and demonstrated clinical efficacy and safety, should be considered as standard, early treatment in patients with relapsed multiple myeloma, especially after first relapse.

Neurologic toxicities of cancer therapies

Neurologic dysfunction is a well-recognized adverse effect of cancer therapeutics. The most common manifestations include peripheral neuropathy and encephalopathy. Often, symptoms resolve or improve upon removal of the offending agent; therefore, it is essential that clinicians recognize the symptoms and signs of injury. Occasionally, symptoms persist or develop after discontinuation of medication and may culminate in disability and diminished quality of life. As our understanding of neurotoxicity improves, medications with less potential for injury may be developed. In addition, potential antidotes to prevent or reverse injury may emerge. This review focuses on the clinical features, mechanisms, and possible therapeutics of the neurotoxicity of chemotherapy. In particular, oxaliplatin, thalidomide, methotrexate, ifosfamide, cytarabine, amifostine, acetyl-L-carnitine, methylene blue, cytokines, and neurotrophins are discussed.

Final Report of Toxicity and Efficacy of a Phase II Study of Oral Cyclophosphamide, Thalidomide, and Prednisone for Patients with Relapsed or Refractory Multiple Myeloma: A Hoosier Oncology Group Trial, HEM01‐21

Thalidomide has direct antimyeloma and immunomodulatory effects. In addition, both thalidomide and metronomic chemotherapy inhibit angiogenesis. The synergy of such a combination may decrease toxicity while maintaining efficacy. The Hoosier Oncology Group conducted a phase II trial of oral cyclophosphamide (50 mg b.i.d. for 21 days), thalidomide (200 mg/day), and prednisone (50 mg q.o.d.) (CTP) per 28-day course in patients with relapsed multiple myeloma (MM). Of the 37 patients enrolled, 16 had prior stem cell transplantation. The median follow-up time was 25.3 months (95% confidence interval [CI] 23.2-27.7). Of 35 patients treated, 22 patients (62.9%) responded: 7 (20.0%) complete responses, 2 (5.7%) near-complete responses, and 13 (37.1%) partial responses. Eight patients (22.9%) had stable disease, and three (8.6%) had disease progression. Two patients withdrew from the study early due to reasons unrelated to progression or toxicity and were treated as nonresponders. The median time to best response and time to progression were 3.6 months (95% CI 2.8-10.9) and 13.2 months (95% CI 9.4-21.0), respectively. The median number of treatment cycles was seven (range 1-12 cycles). Grade III to IV toxicities included leukopenia (42.9%; febrile neutropenia, 11.4%), hyperglycemia (20%), sensory neuropathy (11.4%), thromboses (8%), and motor neuropathy (5.7%). No patient withdrew from the study due to toxicity. The efficacy and low toxicity of the CTP regimen support the future development of such an approach in MM.

Maintenance therapy for multiple myeloma with particular emphasis on thalidomide

Treatment standards are changing as a result of new findings in the therapy of multiple myeloma. So far, prednisone, dexamethasone and interferon-a have mainly been used as maintenance therapy after achieving remission or stable disease. At present, thalidomide is being considered as a new therapeutic option in several studies investigating maintenance therapy. As a result of the dose dependence of adverse effects such as neuropathy, constipation, sedation/vertigo and bradycardia, individual adjustment of the thalidomide dose is recommended. Only isolated cases of thrombosis occurred in the maintenance phase of therapy, and discontinuation of therapy is generally not necessary. While important study results on the efficacy of thalidomide following conventional chemotherapy are still awaited, it is the best documented drug so far for maintenance therapy following autologous stem cell transplantation. An upgrade of the response was seen in 22-73% of patients, as well as a significant prolongation of progression-free survival. For the first time, maintenance therapy with thalidomide showed a significant improvement in overall survival in a phase III study published recently. The tolerability of thalidomide could be further improved by including the option of intermittent administration of the drug.

Scleromyxedema, a positive effect with thalidomide

Scleromyxedema is a rare dermatological disorder marked by widespread symmetric 2- to 3-mm, firm, waxy, closely spaced papules involving the hands, forearms, face, neck, upper trunk and thighs. The most common extracutaneous manifestation of scleromyxedema is a benign plasma cell dyscrasia. Treatment of scleromyxedema is limited by the lack of long-term results, toxicity and significant adverse side effects. We report a severe case of scleromyxedema who had marked improvement when treated with thalidomide.

Advances in oral therapy in the treatment of multiple myeloma

Conventional IV chemotherapy regimens used for induction chemotherapy or salvage therapy in the treatment of multiple myeloma (MM) are cumbersome, with a negative impact on patient quality of life. A number of new oral drugs, including immunomodulatory agents such as thalidomide and lenalidomide, have demonstrated potent antimyeloma activity in relapsed and refractory as well as newly diagnosed MM. Clinically, response rates of 56%-72% have been reported with the combination of thalidomide and dexamethasone in patients with newly diagnosed disease; however, the combination is associated with a higher incidence of side effects, including constipation, somnolence, peripheral neuropathy, and thromboembolic complications. In contrast, preliminary safety and efficacy data from clinical studies of lenalidomide show promise. Response rates as high as 83% have been reported in patients with newly diagnosed MM, and the most common adverse event is manageable myelosuppression, which is reversible with dose reduction. Lenalidomide has different toxicities than thalidomide, exhibiting greater myelosuppression but virtually no constipation, somnolence, or peripheral neuropathy. Oncology nurses play a key role in monitoring patients for side effects and pain control and educating them about emerging treatment options. This article reviews the nursing experience with oral agents in the treatment of MM.

Thalidomide in multiple myeloma: past, present and future

Thalidomide was introduced in the treatment of multiple myeloma in the late 1990s. Following the initial results, which demonstrated dramatic response rates in heavily pretreated patients, a number of Phase II studies have confirmed the efficacy of this agent in relapsed patients. However, a high incidence of side effects at the dosage initially recommended (400 mg/day) justified further studies with lower doses of thalidomide given alone or in combination with dexamethasone or chemotherapy. Thalidomide is currently considered as one of the most active agents in relapsed myeloma. Recent studies have demonstrated that thalidomide could also be used as part of frontline therapy. The combination of thalidomide plus dexamethasone as initial therapy appears to be slightly superior to dexamethasone alone or to vincristine–doxorubicine–dexamethasone, but with an increased risk of deep vein thrombosis. Maintenance with thalidomide after autologous transplantation appears to increase the complete remission rate and to prolong progression-free survival. The combination of thalidomide plus melphalan and prednisone is superior to the classical melphalan–prednisone regimen in elderly patients, and will become the standard of care. Thalidomide has been registered in the USA in combination with dexamethasone in newly diagnosed patients, but is not yet registered in the European Union. Its use is currently challenged by bortezomib and by thalidomide’s analog lenalidomide.

Development of neuropathy in patients with myeloma treated with thalidomide: patterns of occurrence and the role of electrophysiologic monitoring

PURPOSE

Peripheral neuropathy frequently limits the duration of treatment with thalidomide for patients with multiple myeloma. We assessed the time course of occurrence, possible predictive factors, and the utility of serial nerve electrophysiological studies (NES) for detecting onset of neuropathy.

PATIENTS AND METHODS

Seventy-five patients with relapsed/refractory myeloma were enrolled onto a multicenter trial of dose-escalating thalidomide with or without interferon. Patients underwent clinical assessment plus NES at baseline and every 3 months. Time to development of neuropathy according to clinical or NES criteria was compared. Patient and treatment-related factors were compared as predictors of neuropathy.

RESULTS

Thirty-nine percent had some NES abnormalities at baseline. Patients received thalidomide at a median dose-intensity of 373 mg/d. Thirty-one of 75 patients (41%) developed neuropathy during thalidomide treatment; 11 patients (15%) discontinued treatment with thalidomide due to neuropathy. The actuarial incidence of neuropathy increased from 38% at 6 months to 73% at 12 months, with 81% of responding patients developing this complication. Serial NES did not reliably predict the imminent development of clinical neuropathy requiring thalidomide cessation, nor were patient age, sex, or prior therapy predictive. Patients who developed neuropathy had a longer duration of thalidomide exposure (median, 268 v 89 days; P = .0001). Cumulative dose or dose-intensity received was not predictive.

CONCLUSION

The majority of patients will develop peripheral neuropathy given sufficient length of treatment with thalidomide. To minimize the risk of neurotoxicity, therapy should be limited to less than 6 months. Electrophysiologic monitoring provides no clear benefit versus careful clinical evaluation for the development of clinically significant neuropathy.

Neurologic complications of cancer chemotherapy

Neurotoxicity related to cancer therapy is a common problem in oncology practice. Neurologic side effects can be dose-limiting, can inhibit treatment, and can substantially diminish quality of life. Symptoms may appear acutely after treatment, or remotely after therapy has been discontinued. Multiple therapies may share similar toxicities, and certain agents may potentiate symptoms. When faced with the development of neurologic complaints, familiarity with the most common complications is helpful in determining the etiology of these symptoms. This review will discuss the common complications of both established and novel agents used to treat cancer.

Diagnosis, management, and evaluation of chemotherapy-induced peripheral neuropathy

Peripheral neuropathy induced by cancer chemotherapy represents a large unmet need for patients due to the absence of treatment that can prevent or mitigate this common clinical problem. Chemotherapy-induced peripheral neuropathy (CIPN) diagnosis and management is further compounded by the lack of reliable and standardized means to diagnose and monitor patients who are at risk for, or who are symptomatic from, this complication of treatment. The pathogenesis and pathophysiology of CIPN are not fully elucidated, but there is increasing evidence of damage or interference with tubulin function. The diagnosis of CIPN may present a diagnostic dilemma due to the large number of potential toxic etiologies and conditions, which may mimic some of the clinical features; the diagnosis must be approached with care in such patients. The incidence and severity of CIPN is commonly under-reported by physicians as compared with patients. The development of new and reliable methods for the assessment of CIPN as well as safe and effective treatments to prevent this complication of treatment would represent important medical advancements for cancer patients.

Advances in oral therapy for multiple myeloma

Conventional intravenous chemotherapy regimens are toxic, cumbersome, and negatively affect patients' quality of life, with oral treatment preferable to most patients with cancer. Multiple myeloma is the second most common haematological malignant disease, but cannot be cured with conventional and high-dose chemotherapy. New oral treatments that target myeloma cells or bone marrow are being developed that are highly effective yet have low toxic effects, such as the immunomodulatory drugs thalidomide and lenalidomide. Several treatments in early development have shown antimyeloma activity, including: CHIR-258, which inhibits fibroblast growth factor receptor 3; NVP-ADW742, which inhibits insulin-like growth factor receptor 1; and PTK787, which inhibits vascular endothelial growth factor. Additional drugs aimed at switching off silenced genes include histone deacetylase inhibitors. The availability of these various oral treatments is hoped to improve regimens that, if used sequentially or in combination, offer the potential of making multiple myeloma a chronic disease, thereby extending patients' lifespans and improving quality of life.

Oral melphalan and prednisone chemotherapy plus thalidomide compared with melphalan and prednisone alone in elderly patients with multiple myeloma: randomised controlled trial

BACKGROUND

Since 1960, oral melphalan and prednisone (MP) has been regarded as the standard of care in elderly multiple myeloma patients. This multicentre randomised trial compared oral MP plus thalidomide (MPT) with MP alone in patients aged 60-85 years.

METHODS

Patients with newly diagnosed multiple myeloma were randomly assigned to receive oral MP for six 4-week cycles plus thalidomide (n=129; 100 mg per day continuously until any sign of relapse or progressive disease) or MP alone (n=126). Analysis was intention-to-treat. This study is registered at , number NCT00232934.

RESULTS

Patients treated with thalidomide had higher response rates and longer event-free survival (primary endpoints) than patients who were not. Combined complete or partial response rates were 76.0% for MPT and 47.6% for MP alone (absolute difference 28.3%, 95% CI 16.5-39.1), and the near-complete or complete response rates were 27.9% and 7.2%, respectively. 2-year event-free survival rates were 54% for MPT and 27% for MP (hazard ratio [HR] for MPT 0.51, 95% CI 0.35-0.75, p=0.0006). 3-year survival rates were 80% for MPT and 64% for MP (HR for MPT 0.68, 95% CI 0.38-1.22, p=0.19). Rates of grade 3 or 4 adverse events were 48% in MPT patients and 25% in MP patients (p=0.0002). Introduction of enoxaparin prophylaxis reduced rate of thromboembolism from 20% to 3% (p=0.005).

CONCLUSION

Oral MPT is an effective first-line treatment for elderly patients with multiple myeloma. Anticoagulant prophylaxis reduces frequency of thrombosis. Longer follow-up is needed to assess effect on overall survival.

Thalidomide in multiple myeloma

Multiple myeloma is an incurable bone marrow cancer, the treatment of which is notoriously difficult. Only modest advances have been achieved using complex polychemotherapeutic regimens, transplant strategies and supportive therapy. In 1999, when new drugs for myeloma were urgently needed, thalidomide was introduced and opened up a completely new line of therapy for the disease. Although the mechanism of action is not yet completely understood, thalidomide has demonstrated efficacy in patients with refractory, relapsed myeloma, even in late-stage cases. This article reviews the current knowledge of thalidomide in myeloma treatment, focusing especially on the possible mechanisms of action, clinical results and adverse events of this drug.

Toxic neuropathy

PURPOSE OF REVIEW

This paper examines recent research on toxic neuropathy and potential therapeutic developments. It also summarizes reports of new agents reported to cause peripheral neuropathy.

RECENT FINDINGS

Gene therapy with vasoactive endothelial growth factor, neurotrophic substances such as nerve growth factor and neurotrophin-3 are reported to reverse or protect against neurotoxicity in animal models. The neuroprotective effects of more established therapeutic agents like vitamin E, tacrolimus (FK 506) and erythropoietin hold promise for the immediate future. Cisplatin and high-dose pyridoxine are used more frequently to produce robust models of peripheral neuropathy in animals. Statins do appear to cause peripheral neuropathy. The incidence is low, however, and compared to its benefits in terms of cardiovascular protection, relatively innocuous. The profile of thalidomide neuropathy is becoming clearer as the indications for this drug increases. The incidence of thalidomide neuropathy is high, up to three quarters in some series, and although the information on dose dependency is variable, lower cumulative doses appear to be less toxic. Like thalidomide bortezomib, a novel proteosome inhibitor, is reportedly effective in the treatment of multiple myeloma and is associated with peripheral neuropathy. Oxaliplatin and epothilone are emerging anticancer drugs with neurotoxic potential. Similarly, leflunomide, a new disease modifying-agent approved for the treatment of rheumatoid arthritis, is reported to cause neuropathy.

SUMMARY

The study of toxic neuropathy is not only enhancing our knowledge of the mechanisms of neurotoxicity but also the neurobiology of peripheral neuropathy in general; and is likely to reveal avenues for therapeutics.