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Updated efficacy and toxicity of treatment with the anti-CTLA-4 antibody ipilimumab in metastatic melanoma patients previously treated with anti-PD-1 therapy
  1. Prashanth Prithviraj1,
  2. Grant McArthur2,
  3. Victoria Atkinson3,
  4. Phillip Parente4,
  5. Miles Andrews1,
  6. Sagun Parakh1,
  7. Michael Millward5,
  8. Jonathan Cebon6 and
  9. Oliver Klein1
  1. Aff1 grid.410678.cMedical Oncology, Austin Health Heidelberg Australia
  2. Aff2 grid.1055.10000000403978434Peter MacCallum Cancer Centre East Melbourne Australia
  3. Aff3 grid.412744.00000000403802017Princess Alexandra Hospital Woolloongabba Australia
  4. Aff4 grid.414580.c0000000104592144Eastern Health Clinical SchoolBox Hill Hospital Box Hill Australia
  5. Aff5 grid.3521.50000000404375942Sir Charles Gairdner Hospital Nedlands Australia
  6. Aff6 grid.482637.cOlivia Newton-John Cancer Research Institute Heidelberg Australia

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Meeting abstracts


Immunotherapy with anti-CTLA-4 and anti-PD-1 antibodies has demonstrated overall survival benefits in patients (pts) with metastatic melanoma (MM) compared to previous standard therapy. Two randomised clinical trials indicate that combined anti-CTLA-4 and anti-PD-1 antibody therapy increases the response rate compared to single agent treatment, but is associated with increased toxicity [1, 2]. Both efficacy and toxicity of anti-PD-1 therapy appear independent of prior treatment with the anti-CTLA-4 antibody ipilimumab. To date, only limited evidence exists regarding the efficacy and toxicity of Ipilimumab in pts that have progressed on treatment with an anti-PD-1 agent.


We retrospectively identified pts with MM who received anti-PD-1 therapy (Nivolumab/Pembrolizumab) and were subsequently treated with ipilimumab. Ipilimumab was administered at a dose of 3mg/kg every three weeks for (up to) four doses and response assessed by CT scan 4-6 weeks after the last dose. Efficacy and toxicity outcomes were determined from clinical records.


The median age was 53 years with all pts having stage IVc disease and 4 pts (33%) with an elevated LDH at commencement of Ipilimumab dosing. The median time between the last dose of anti-PD-1 therapy and the commencement of Ipilimumab was 8 months (range 2-14 months). After a median follow-up of over 6 months, 1 patient (8%) achieved a partial remission as their best response to anti-PD-1 therapy with an additional 6 (50%) having stable disease. Five patients (42%) received all four doses of Ipilimumab. Two patients (17%) achieved an objective response to ipilimumab with another having prolonged stable disease. Four patients experienced grade 3/4 immune-related adverse events (irAE) including colitis (n=3) and pneumonitis (n=1).


Ipilimumab therapy can induce responses in patients who have failed treatment with an anti-PD-1 antibody. The response rate and clinical benefit rate appears similar compared to outcomes in pts who have not received prior anti-PD-1 antibody therapy. Although cases of severe and/or unusual irAEs such as pneumonitis have been observed, an analysis of a larger patient cohort will be required to test the significance of these observations.


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