Targeted immunotherapy for hairy cell leukemia

Hairy cell leukemia: short review, today's recommendations and outlook

Hairy cell leukemia (HCL) is part of the low-grade non-Hodgkin lymphoma family and represents approximately 2% of all leukemias. Treatment with splenectomy and interferon-α historically belonged to the first steps of therapeutic options, achieving partial responses/remissions (PR) in most cases with a median survival between 4 and 6 years in the 1980s. The introduction of the purine analogs (PA) pentostatin and cladribine made HCL a well-treatable disease: overall complete response rates (CRR) range from 76 to 98%, with a median disease-free survival (DFS) of 16 years a normal lifespan can be reached and HCL-related deaths are rare. However, insufficient response to PA with poorer prognosis and relapse rates of 30–40% after 5–10 years of follow-up may require alternative strategies. Minimal residual disease can be detected by additional examinations of bone marrow specimens after treatment with PA. The use of immunotherapeutic monoclonal antibodies (mAB) like rituximab as a single agent or in combination with a PA or more recently clinical trials with recombinant immunotoxins (RIT) show promising results to restrict these problems. Recently, the identification of the possible disease-defining BRAF V600E mutation may allow the development of new therapeutic targets.

Antibody phage display libraries: contributions to oncology

Since the advent of phage display technology, dating back to 1985, antibody libraries displayed on filamentous phage surfaces have been used to identify specific binders for many different purposes, including the recognition of tumors. Phage display represents a high-throughput technique for screening billions of random fusion antibodies against virtually any target on the surface or inside cancer cells, or even soluble markers found in patient serum. Many phage display derived binders targeting important tumor markers have been identified. Selection directed to tumoral cells’ surfaces lead to the identification of unknown tumoral markers. Also the improvement of methods that require smaller amounts of cells has opened the possibility to use this approach on patient samples. Robust techniques combining an antibody library displayed on the phage surface and protein microarray allowed the identification of auto antibodies recognized by patient sera. Many Ab molecules directly or indirectly targeting angiogenesis have been identified, and one of them, ramucirumab, has been tested in 27 phase I–III clinical trials in a broad array of cancers. Examples of such antibodies will be discussed here with emphasis on those used as probes for molecular imaging and other clinical trials.