New Drug of the day : PLERIXA

New Pharmacological Drug Classes Introduced in 2008 

Plerixa started out as an investigational anti-retroviral drug for the treatment of AIDS. An unexpected finding of increased CD34+ hematopoietic stem cell counts in the peripheral blood of subjects exposed to the drug eventually lead to its licensing for use in combination with granulocyte-colony stimulating factor (G-CSF) to mobilize hematopoietic stem cells to the peripheral blood for collection prior to autologous transplantation in patients with non-Hodgkin’s lymphoma and multiple myeloma.

Plerixa is an inhibitor of the CXCR4 chemokine receptor. 

CXCR4, is normally responsible for ‘‘homing’’ (anchoring) stem cells in the bone marrow.¹⁶ Plerixa antagonizes the interaction between CXCR4 and its cognate ligand, stromal cell-derived factor-1α. Plerixa works synergistically with G-CSF and is given after "priming" with 4 daily doses of G-CSF. Plerixa is administered subcutaneously, in a dose of 0.24 mg/kg (up to 40 mg), approximately 11 hours prior to an apheresis session, in conjuction with additional daily G-CSF, for up to 4 consecutive days. 

Approximately 1/2 of non-Hodgkins lymphoma patients receiving plerixa will achieve a yield >5 x 10⁶ CD34+ cell harvests after 2 apheresis sessions. 

Data for patients with multiple myeloma suggests that approximately 75% will achieve a yield >6 x 10⁶ CD34+ cell harvests after 2 apheresis sessions. Plerixa is primarily eliminated by the kidneys. Drug-drug interactions may result from coadministration with drugs that reduce renal function or compete for active tubular secretion. (See Figure 4.) (CID: 16727404) 

The most common adverse reactions reported in patients who received plerixa in conjunction with G-CSF and aphresis were diarrhea, nausea, fatigue, injection site reactions, headache, arthralgia, dizziness, vomiting, abdominal pain, hyperhidrosis, abdominal distention, dry mouth, erythema, stomach discomfort, malaise, hypoesthesia, constipation, dyspepsia, and musculoskeletal pain.