In previous studies of CLBS20—a patient-specific therapeutic vaccine consisting of autologous dendritic cells loaded with antigens from irradiated cells from an autologous tumor cell line—the vaccine was associated with a 72% two-year overall survival (OS), with the most common toxicities including mild local injection site reactions. A recent study provided long-term survival data for patients treated with CLBS20. The researchers presented the study at the ASCO Annual Meeting. 

Between 2001 and 2011, 72 patients (45 men and 27 women) with stage 4 (n = 52) or recurrent stage 3 (n = 20) melanoma were treated with CLBS20. Each patient had a metastatic melanoma lesion surgically resected, from which a tumor cell line was established. Cells were incubated with autologous dendritic cells to produce the vaccine that was injected subcutaneously in 500 micrograms sargramostim (GM-CSF) weekly for three weeks and months for the subsequent five months. 

The median patient age was 52 years (range = 17–83). Tumor sources included lymph node (n = 37), soft tissue (n = 15), and viscera (n = 20). 

Patients had received the following prior therapies.

  • Surgery (n = 72)
  • Chemotherapy (n = 41)
  • Interluekin-2 (n = 33)
  • Interferon alpha (n = 30)
  • GM-CSF (n = 24)
  • Radiation therapy ([RT]; n = 19)
  • RT for brain metastases (n = 15)

Thirty-three patients survived and were followed for the full five years. The median OS was 45.6 months, with a 46% five-year OS rate. The median progression-free survival (PFS) was 4.4 months, with a 19% five-year PFS rate.

Among those with recurrent stage 3 melanoma, the five-year OS was 70% and the median PFS was 19.8 months, with a 35% five-year PFS rate. Among those with stage 4 disease, the median OS was 41 months, with a five-year OS of 36%, while the median PFS was 3.8 months.

One patient with refractory progressive measurable disease experienced delayed complete response that was ongoing at five years.

The researchers concluded, “CLBS20 is associated with encouraging five-year OS. Because of its unique mechanism of action and absence of toxicity, it should be evaluated further in similar patients.”