Tumor Protein Predicts Response of Head and Neck Cancer to Abraxane™
Levels of the albumin-binding protein known as SPARC (Secreted Protein Acidic Rich in Cysteine) are highly associated with the response of head and neck cancer to treatment with Abraxane™ (albumin-bound paclitaxel), according to study results presented at the 23rd annual Chemotherapy Foundation Symposium in New York.
Head and neck cancers originate in the throat, larynx (voice box), pharynx, salivary glands, or oral cavity (lip, mouth, tongue). Most head and neck cancers involve squamous cells, which line the mouth, throat, and other structures.
Abraxane is a new form of the chemotherapy drug paclitaxel. Abraxane is bound to albumin, a type of protein normally found in the human body. This form of paclitaxel delivers high concentrations of the active ingredient into the cancer cells and, compared to its original form, reduces the frequency of side effects. Abraxane has demonstrated significant activity in various cancers, including cancers of the head and neck. Abraxane is moving forward through clinical trials as safety and efficacy data mature.
An important area of research that is receiving increasing attention is individualized treatment; the emphasis of this research is on identifying and defining specific “markers” associated with different outcomes among patients who share the same clinical diagnosis. One potential predictor of treatment response in patients treated with Abraxane is SPARC (Secreted Protein Acidic Rich in Cysteine). SPARC is a protein that is secreted by many cancers and may play a role in the accumulation of albumin and albumin-targeted agents within a tumor.
To evaluate whether the presence of SPARC predicts response to treatment with Abraxane, researchers evaluated treatment outcomes among patients with head and neck cancer. They found that the presence of SPARC was associated with a greater response to Abraxane:
- Complete or partial disappearance of detectable cancer occurred in 83% of patients who were SPARC-positive and only 25% of patients who were SPARC-negative.
- Cancer progression during treatment with Abraxane occurred in only 6% of patients who were SPARC-positive, but 50% of patients who were SPARC-negative.
The researchers concluded that tumor levels of SPARC appear to be highly associated with response to Abraxane; those who were SPARC-positive had significantly greater responses to treatment with Abraxane than those who were SPARC-negative. These results may ultimately help physicians identify those patients who are most likely to respond to treatment with Abraxane. The authors of the study note, however, that this was a small study and that further studies are needed to confirm these findings.
Reference: Hawkins M, Desai N, Soon-Shiong P, et al. Experience with ABI-007 (Abraxane™) administered by intra-arterial infusion to patients with cancers of the head and neck. Proceedings from the 23rd annual Chemotherapy Foundation Symposium. Presented November 3, 2005. New York. Abstract #25.