The Pathophysiology of Bortezomib Induced Peripheral Neuropathy

Is There a Role of Oxidative Stress in the Pathophysiology of Bortezomib Induced Peripheral Neuropathy (BIPN) in Multiple Myeloma Patients?

Since the pathophysiology of BIPN still remains unclear, in the present study we are going to assess the development of BIPN in newly diagnosed myeloma patients, based on clinical neurological examination and electrophysiological study (EMG) and trying to find out if there is any relationship between oxidative stress generation measured by serum malonyldialdehyde - (MDA) and urinary isoprostane, and the development of BIPN, which can explain important part of the BIPN pathophysiology and can suggest new ideas of treatment and prophylactic strategies of peripheral neuropathy.

The proteasome inhibitor bortezomib has shown impressive clinical activity alone and in combination with other novel agents for the treatment of multiple myeloma (MM).

Peripheral neuropathy is a significant dose limiting toxicity of bortezomib, which typically occurs within the first treatment cycles with bortezomib, reaching plateau around cycle 5, and does not appear to increase thereafter.

Although bortezomib is known to be selective proteasome inhibitor, the mechanisms of cytotoxicity are poorly understood.

It has been theoretically hypothesized that bortezomib abrogates the degradation of I-kB, which blocks the transcriptional activity of NF-kB, however, recent studies demonstrated that bortezomib elicits activation of multiple pathways in cancer cells, such as reactive oxygen species (ROS) pathway.

The involvement of oxidative stress is supported by emerging studies showing that ROS generation plays a critical role in the initiation of the bortezomib induced apoptotic cascade.

Oxidative stress is a complex and dynamic situation characterized by an imbalance between the productions of ROS and the availability and action of antioxidants.

Inclusion Criteria:

1. A total of 30 newly diagnosed patients (age > 18 years) with multiple myeloma (stage3 Durie and Salmon, ECOG-performance status <2), who are candidates for bortezomib therapy will be enrolled in the study (duration of the study 6 months).

Exclusion Criteria:

1. Patients with relapsed or progressive multiple myeloma.
2. Performance status > 2.
3. Prior treatment with neuropathic agents such as Oncovin and thalidomide.