Fc-Optimized Anti-CCR8 Antibody Depletes Regulatory T Cells in Human Tumor Models.

FOXP3+ regulatory T cells (Treg) play a critical role in mediating tolerance to self-antigens and can repress antitumor immunity through multiple mechanisms. Therefore, targeted depletion of tumor-resident Tregs is warranted to promote effective antitumor immunity while preserving peripheral homeostasis. Here, we propose the chemokine receptor CCR8 as one such optimal tumor Treg target. CCR8 was expressed by Tregs in both murine and human tumors, and unlike CCR4, a Treg depletion target in the clinic, CCR8 was selectively expressed on suppressive tumor Tregs and minimally expressed on proinflammatory effector T cells (Teff). Preclinical mouse tumor modeling showed that depletion of CCR8+ Tregs through an FcyR-engaging anti-CCR8 antibody, but not blockade, enabled dose-dependent, effective, and long-lasting antitumor immunity that synergized with PD-1 blockade. This depletion was tumor Treg-restricted, sparing CCR8+ T cells in the spleen, thymus, and skin of mice. Importantly, Fc-optimized, nonfucosylated (nf) anti-human CCR8 antibodies specifically depleted Tregs and not Teffs in ex vivo tumor cultures from primary human specimens. These findings suggest that anti-CCR8-nf antibodies may deliver optimal tumor-targeted Treg depletion in the clinic, providing long-term antitumor memory responses while limiting peripheral toxicities. SIGNIFICANCE: These findings show that selective depletion of regulatory T cells with an anti-CCR8 antibody can improve antitumor immune responses as a monotherapy or in combination with other immunotherapies. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/11/2983/F1.large.jpg.

Blastic mantle cell lymphoma developing concurrently in a patient with chronic myelogenous leukemia and a review of the literature.

Non-Hodgkin's lymphoma (NHL) occurring as a synchronous malignancy with chronic myelogenous leukemia (CML) is rare. To our knowledge, this is the first case reported of a patient who developed mantle cell lymphoma (MCL) after therapy with imatinib mesylate for CML. After a 3-year history of CML, the patient developed a lymphocytosis associated with diarrhea, anorexia, and weight loss. Imaging studies revealed abdominal adenopathy and extensive lymphomatous infiltration of the liver, stomach, pancreas, and kidneys. Flow cytometric and cytogenetic studies were consistent with MCL. Fluorescence in situ hybridization (FISH) of the bone marrow revealed a genetically distinct lymphoid neoplasm rather than an extramedullary blast crisis of CML. The development of lung cancer, prostate cancer, CML and MCL in this patient suggests a genetic predisposition, although other factors, including environmental exposures and therapy with imatinib mesylate could have had a contributory or synergistic role in the development of MCL.

Allele-specific Holliday junction formation: a new mechanism of allelic discrimination for SNP scoring.

We report here a new mechanism for allelic discrimination--allele-specific Holliday Junction formation. The Holliday Junction (HJ) is a unique DNA structure that can be formed in a sequence-nonspecific manner by routine PCR. To cause the PCR-based HJ formation to occur in an allele-specific manner, the PCR primers are manipulated such that an extra mismatch next to a SNP of interest is introduced between a target and a reference amplicon and a GC-clamp is added. Based on this new mechanism, novel SNP genotyping methods were developed, including a homogeneous fluorescence polarization (FP) competition assay that requires neither labeled primers/probes nor expensive enzymes/substrates. Using this novel genotyping technology, we were able to convert >95% of SNP sequences into genotyping assays that work well under a universal set of assay conditions and achieved 100% accuracy in clinical samples.