Memgen announced that positive data evaluating its active cellular immunotherapy product, ISF35, in combination with chemotherapy in resistant chronic lymphocytic leukaemia (CLL) were presented December 7 during the 51st Annual Meeting of the American Society of Haematology (Abstract #376). The ongoing phase-Ib trial's first two patients have both achieved minimal residual disease-negative (MRD-) complete responses, according to Januario Castro, associate clinical professor, Bone Marrow Transplant Division of the University of California, San Diego (UCSD).

The study, which is co-sponsored by the Leukaemia & Lymphoma Society, evaluated three infusions of patients' CLL cells exposed outside the body to ISF35 followed by standard chemo-immunotherapy (fludarabine, cyclophosphamide, and Rituxan, also known as FCR).

Both patients had high-risk CLL with 17p deletion, which is associated with short survival and resistance to treatment. By comparison, less than 11 per cent of patients with this condition achieve a complete response to FCR chemotherapy without ISF35, according to the presentation.

"These are very encouraging results, especially in the setting of patients with high risk CLL," said Dr Castro. "If our preliminary results are confirmed this new therapy could be a breakthrough for patients with refractory and 17p-deleted CLL."

The ISF35 plus FCR regimen has been well-tolerated so far. Patients have experienced mild flu-like symptoms after receiving ISF35-modified cells, and have encountered expected side effects with the chemotherapy.

The responses have been corroborated by laboratory studies performed on blood samples from each patient in conjunction with the trial. These tests confirmed in the first patient that the CLL cells were resistant to fludarabine prior to the trial, but were significantly sensitized to fludarabine after receiving ISF35-modified cells. The laboratory studies also indicated that the CLL cells may be destroyed through p53-independent pathways opened by ISF35, including p73 and p21, providing some insight into the mechanism of re-sensitization.

There is no cure for CLL, which is the most common leukaemia in the US. Although all cases of CLL are difficult to treat, patients with refractory and high-risk disease, including those with 17p deletion, tend to show much lower survival and rates of response. Researchers everywhere continue to seek new and effective treatment options for these CLL patients.

Memgen is a clinical stage biotechnology company headquartered in Dallas, Texas, that is dedicated to developing therapies that improve overall survival in patients with blood and solid tumour cancers.