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Plerixafor (Mozobil)

Written by The Peptide Record editorialClinical review not yet completedLast reviewed 15 September 2026Funding No ads, no affiliate links, no vendor payment

Plerixafor is the original CXCR4-antagonist stem-cell mobilizer — the drug this site's Motixafortide page mentions only in passing, as "a smaller CXCR4-antagonist molecule" approved for the same job in 2008. It got there first, on the strength of two placebo-controlled Phase 3 trials, and it got there almost by accident: discovered as an anti-HIV compound, then redirected into oncology supportive care after researchers noticed it was spiking patients' white blood cell counts as a side effect. Its patents expired in 2023, and by mid-2024 several generic manufacturers had entered the US market at a small fraction of the brand price.

On this page
  1. An HIV drug that mobilized stem cells by accident
  2. The pivotal 3101 and 3102 trials
  3. FDA approval and how it's used
  4. Investigational in WHIM syndrome — not an approved use
  5. Current status: generics, and how it compares to motixafortide

In brief

Should you care? Relevant mainly if you or someone you know is preparing for an autologous stem cell transplant — this is the original, still first-line CXCR4-antagonist add-on to G-CSF, and the predecessor this site's Motixafortide page names directly.

The short version

  • What it is: a small bicyclam molecule (not a peptide) that blocks the CXCR4 receptor, releasing blood-forming stem cells from bone marrow into circulation — the same target motixafortide's cyclic peptide binds, by a chemically unrelated route.
  • Evidence: two placebo-controlled Phase 3 trials found it roughly tripled the rate of hitting the stem-cell collection target — 59% vs 20% in non-Hodgkin lymphoma, 71.6% vs 34.4% in multiple myeloma — each added on top of standard G-CSF.
  • FDA-approved 15 December 2008, the first CXCR4 antagonist ever cleared for any use; generic versions have been available since July 2023.

An HIV drug that mobilized stem cells by accident

Plerixafor started life as AMD3100, a small bicyclam molecule developed by AnorMED as a CXCR4-blocking anti-HIV compound, meant to stop the virus from using CXCR4 as a co-receptor to enter T cells. In early HIV trials, it worked as an antiviral against CXCR4-tropic (X4) strains — but researchers also noticed an unrelated, unexpected side effect: a sharp, transient rise in circulating white blood cells. That observation, not the antiviral result, is what redirected the molecule's entire development path. CXCR4 turned out to be the same receptor that normally tethers hematopoietic stem cells inside bone marrow, bound to its ligand CXCL12 (SDF-1); blocking it released stem cells into the bloodstream, which is exactly what a transplant team needs before apheresis. Genzyme Corporation acquired AnorMED in 2006 and carried the drug the rest of the way through oncology-supportive-care development, dropping the HIV indication entirely. Chemically, plerixafor has nothing in common with motixafortide — a bicyclam small molecule against a cyclic peptide — but the two drugs block the identical CXCR4/CXCL12 axis, on different dosing schedules: plerixafor once daily for up to four days, motixafortide as a single longer-acting dose.

The pivotal 3101 and 3102 trials

Plerixafor's approval rests on two near-identically designed, randomized, double-blind, placebo-controlled Phase 3 trials, each testing it in combination with G-CSF against placebo plus G-CSF. Study 3101 (DiPersio JF, Micallef IN, Stiff PJ, et al., "Phase III Prospective Randomized Double-Blind Placebo-Controlled Trial of Plerixafor Plus Granulocyte Colony-Stimulating Factor Compared With Placebo Plus Granulocyte Colony-Stimulating Factor for Autologous Stem-Cell Mobilization and Transplantation for Patients With Non-Hodgkin's Lymphoma," J Clin Oncol 2009;27(28):4767-4773, PMID 19720922, DOI 10.1200/JCO.2008.20.7209) enrolled 298 non-Hodgkin lymphoma patients; its primary endpoint — collecting at least 5×10⁶ CD34+ cells/kg within 4 apheresis days — was met by 59% of the plerixafor group versus 20% of the placebo group. Study 3102 (DiPersio JF, Stadtmauer EA, Nademanee A, et al., "Plerixafor and G-CSF versus placebo and G-CSF to mobilize hematopoietic stem cells for autologous stem cell transplantation in patients with multiple myeloma," Blood 2009;113(23):5720-5726, PMID 19363221, DOI 10.1182/blood-2008-08-174946) enrolled 302 multiple myeloma patients, with a higher target of 6×10⁶ CD34+ cells/kg within 2 apheresis days, met by 71.6% (106 of 148) of the plerixafor group versus 34.4% (53 of 154) of the placebo group. Across both trials, plerixafor patients also collected their target cell dose in fewer apheresis sessions overall; the most common adverse reactions were gastrointestinal (diarrhea, nausea) and mild injection-site reactions.

FDA approval and how it's used

The FDA approved Mozobil on 15 December 2008 (Genzyme Corporation), in combination with G-CSF, to mobilize hematopoietic stem cells to the peripheral blood for collection and subsequent autologous transplantation in patients with non-Hodgkin lymphoma or multiple myeloma — the first CXCR4 antagonist ever approved for any indication. The European Medicines Agency followed on 31 July 2009. It's dosed at 0.24 mg/kg by subcutaneous injection, approximately 11 hours before apheresis begins, after 4 days of once-daily morning G-CSF, and can be continued for up to 4 consecutive days if additional apheresis sessions are needed. The label carries no boxed warning, but does warn of hypersensitivity reactions, of tumor-cell mobilization (plerixafor is contraindicated in leukemia, where releasing malignant cells into circulation is a genuine risk rather than the intended one), and — because it's always given alongside G-CSF, which carries the same warning on its own — of splenic enlargement and, rarely, rupture, evaluated by any new left-upper-abdominal, shoulder, or scapular pain during treatment.

Investigational in WHIM syndrome — not an approved use

The mechanism fits — but a different drug won the approval

WHIM syndrome is a rare, inherited immunodeficiency caused by a gain-of-function CXCR4 mutation — the mirror image of what plerixafor blocks, so a CXCR4 antagonist is a mechanistically obvious idea. NIAID ran an investigator-initiated, quadruple-masked Phase 3 crossover trial (McDermott DH, Velez D, Cho E, et al., "A phase III randomized crossover trial of plerixafor versus G-CSF for treatment of WHIM syndrome," J Clin Invest 2023;133(19):e164918, PMID 37561579, DOI 10.1172/JCI164918), giving 19 WHIM patients 12 months of each drug. Plerixafor was not superior to G-CSF on the primary endpoint, a total infection severity score (p=0.54), though it was noninferior at maintaining neutrophil counts and superior at maintaining lymphocyte counts, and produced substantial regression of wart burden in 5 of 7 patients who had major warts at baseline. Despite that real, published data, plerixafor was never submitted for, or granted, an FDA approval in WHIM syndrome. That approval went instead to a different, oral CXCR4 antagonist, mavorixafor (Xolremdi), cleared by the FDA on 29 April 2024 as the first — and, as of this review, only — approved WHIM syndrome treatment.

It's a genuinely different situation from the investigational uses covered on this site's Motixafortide page: there, the open questions (pancreatic cancer, sickle cell disease mobilization) simply haven't reached a regulatory decision yet. Here, a same-mechanism competitor built specifically for WHIM syndrome has already reached the market plerixafor's own trial helped establish was worth pursuing.

Current status: generics, and how it compares to motixafortide

Sanofi (through Genzyme) continues to market brand-name Mozobil in the US, but patent protection lapsed in mid-2023, and the FDA approved the first generic plerixafor injections on 24 July 2023 — Amneal, Dr. Reddy's, and Eugia among the first manufacturers cleared — with additional generic approvals following into 2024. As of mid-2024, Sanofi's branded Mozobil listed at roughly $11,961 per 24mg vial, against generic pricing reported in the $600-$2,040 range. Plerixafor remains the default, now comparatively inexpensive, first-line CXCR4-antagonist add-on to G-CSF for stem-cell mobilization in non-Hodgkin lymphoma and multiple myeloma; motixafortide, still brand-only and considerably more expensive, is positioned as a newer, single-dose alternative used mainly where plerixafor-based mobilization has failed or is expected to underperform, not as a wholesale replacement for it. Given how recently that generic entry happened, the specific price gap between the two drugs is worth checking against a current source rather than assuming today's figures hold indefinitely.

References

  1. DiPersio JF, Micallef IN, Stiff PJ, et al., "Phase III Prospective Randomized Double-Blind Placebo-Controlled Trial of Plerixafor Plus Granulocyte Colony-Stimulating Factor Compared With Placebo Plus Granulocyte Colony-Stimulating Factor for Autologous Stem-Cell Mobilization and Transplantation for Patients With Non-Hodgkin's Lymphoma," J Clin Oncol 2009;27(28):4767-4773, PMID 19720922, DOI: 10.1200/JCO.2008.20.7209.
  2. DiPersio JF, Stadtmauer EA, Nademanee A, et al., "Plerixafor and G-CSF versus placebo and G-CSF to mobilize hematopoietic stem cells for autologous stem cell transplantation in patients with multiple myeloma," Blood 2009;113(23):5720-5726, PMID 19363221, DOI: 10.1182/blood-2008-08-174946.
  3. McDermott DH, Velez D, Cho E, et al., "A phase III randomized crossover trial of plerixafor versus G-CSF for treatment of WHIM syndrome," J Clin Invest 2023;133(19):e164918, PMID 37561579, DOI: 10.1172/JCI164918.
  4. FDA approval of Mozobil (plerixafor injection), NDA 022311, 15 December 2008 (Genzyme Corporation); European Medicines Agency marketing authorisation, 31 July 2009. FDA approval of mavorixafor (Xolremdi) for WHIM syndrome, 29 April 2024.
  5. FDA approval of first generic plerixafor injections, 24 July 2023 (Amneal Pharmaceuticals, Dr. Reddy's Laboratories, Eugia Pharma, among others), with further generic approvals through 2024; pricing comparison of branded Mozobil versus generic plerixafor as of mid-2024, cross-checked across drug-pricing trade coverage rather than a single source.