Hypersensitivity Reactions to Obinutuzumab in Cynomolgus Monkeys and Relevance to Humans.

Obinutuzumab (GA101, Gazyva™, Gazyvaro®, F. Hoffmann-La Roche AG, Basel, Switzerland) is a humanized, glycoengineered type II antibody targeted against CD20. The preclinical safety evaluation required to support clinical development and marketing authorization of obinutuzumab included repeat-dose toxicity studies in cynomolgus monkeys for up to 6-month dosing with a 9-month recovery period. Results from those studies showed decreases in circulating B cells and corresponding B-cell depletion in lymphoid tissues, consistent with the desired pharmacology of obinutuzumab. Hypersensitivity reactions were noted at all doses in the 6-month study and were attributed to the foreign recognition of the drug construct in cynomolgus monkeys. Findings in monkeys were classified as acute hypersensitivity reactions that were evident immediately after dosing, such as excessive salivation, erythema, pruritus, irregular respiration, or ataxia, or chronic hypersensitivity reactions characterized by glomerulonephritis, arteritis/periarteritis, and inflammation in several tissues including serosal/adventitial inflammation. Immune complex deposits were demonstrated in tissues by immunohistochemistry, immunofluorescence, and electron microscopy. Some of, but not all, the animals that developed these reactions had detectable antidrug antibodies or circulating immune complexes accompanied by loss of drug exposure and pharmacodynamic effect. On the basis of clinical evidence to date, hypersensitivity reactions following obinutuzumab are rare, further supporting the general view that incidence and manifestation of immunogenicity in nonclinical species are generally not predictive for humans.

Treatment of splenic marginal zone lymphoma: splenectomy versus rituximab.

Splenic marginal zone lymphoma (SMZL) is an uncommon indolent B-cell lymphoma causing marked splenic enlargement with CD20-rich lymphoma cells infiltrating blood and bone marrow. In the pre-rituximab era, the treatment of choice for patients with symptomatic splenomegaly or threatening cytopenia was splenectomy, since chemotherapy had limited efficacy. Responses to splenectomy occurred in approximately 90% of patients. However, SMZL patients are often elderly and poor surgical risks. Since approval of rituximab, treatment of such patients with the anti-CD20 antibody both alone or in combination with chemotherapy has shown remarkable responses. In retrospective series of rituximab monotherapy totaling 52 patients, including both chemotherapy-naive and -refractory patients, overall responses of 88% to 100% were noted with marked and prompt regression of splenomegaly and improvement of cytopenias. Sustained responses occurred both with and without rituximab maintenance in 60% to 88% of patients at 3 years. Relapsed patients responded to second courses of rituximab monotherapy. Overall survival was comparable to that reported following splenectomy. Rituximab in combination with purine nucleosides may provide further improvement in progression-free survival; however, confirmatory prospective trials are necessary. These results suggest that splenectomy should no longer be considered as initial therapy for SMZL but rather as palliative therapy for patients not responsive to immunotherapy with or without chemotherapy.

Characterization of novel murine anti-CD20 monoclonal antibodies and their comparison to 2B8 and c2B8 (rituximab).

Rituximab is the first anti-cancer antibody approved by the FDA for the treatment of B-cell non-Hodgkin lymphoma (B-NHL), alone or in combination with chemotherapeutic drugs. Further, rituximab is now being examined in a variety of CD20+ neoplastic diseases as well as B-cell-induced autoimmune diseases. The clinical response to rituximab is significant, resulting not only in tumor regression but also prolongation of survival. However, a subset of patients does not initially respond to rituximab or develops resistance to its further treatment. Therefore, alternative therapies for these patients are strongly desired. Rituximab activity has been thought to be by antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity and apoptosis, and studies in model systems established the role of rituximab in cell signaling-induced perturbation of anti-apoptotic survival pathways, suggesting that the patients unresponsive to rituximab may be overcome with other CD20 antibodies with different activities. This study investigated eight novel murine antibodies directed against CD20 for their physical and biological properties in comparison with 2B8 and c2B8 (rituximab). These antibodies were derived by various antigenic and immunization procedures and selected for CD20 activity. Analysis of these antibodies revealed that they all bound to various B-cell lines and CD20-transfected CHO cells. Six of the eight antibodies shared similar variable-region amino acid sequences that were also shared by 2B8 while two monoclonal antibodies did not. Of them, 1K1791 has a distinct heavy chain and both 1K1791 and 1K1782 have distinct light chains. Not all of the antibodies inhibited cell growth and only two antibodies reacted with fixed GST-CD20 recombinant fusion protein. Noteworthy, 1K1791 was found to inhibit cell proliferation and also induced caspase-independent apoptosis in the absence of cross-linker. These findings identified new antibodies with properties and epitope specificities different from 2B8. The potential clinical application of such antibodies in the treatment of B-NHL and rituximab-resistant B-NHL is discussed.

Intravascular large B-cell lymphoma involving hemangiomas: an unusual presentation of a rare neoplasm.

We report the clinicopathological features of two cases of intravascular large B-cell lymphoma involving cutaneous hemangiomas. The cases were identified from the consultation files of two of the authors. Both patients were women, 64 and 55 years of age, who presented with long-standing cutaneous hemangiomas of the posterior scalp and left shoulder, respectively. The lesions were brought to medical attention by an increase in size and change in color. Biopsies and immunohistochemical evaluation of the hemangiomas revealed extensive involvement by intravascular large B-cell lymphoma. The neoplastic cells were diffusely positive for CD20 in both cases and negative for CD3, pan-cytokeratin (AE1/AE3), epithelial membrane antigen, S-100, Factor VIII-related antigen, CD34 and CD31. Disease was limited to the hemangiomas in both patients. Treatment consisted of chemotherapy (both patients) and adjuvant radiation therapy (one patient). One patient had a recurrence of disease 33 months after initial diagnosis, leading to an autologous stem cell transplant. The other patient is without evidence of disease 27 months after initial diagnosis. Although this is a rare neoplasm, it is important to consider intravascular large B-cell lymphoma in the differential diagnosis of vascular lesions containing intravascular neoplastic cells.

Sentinel lymph nodes show profound downregulation of antigen-presenting cells of the paracortex: implications for tumor biology and treatment.

The sentinel lymph node (SN) is the first node on the direct lymphatic drainage pathway from a tumor. Melanoma-associated SNs are the most likely site of early metastases and their immune functions are strikingly down-modulated. We evaluated histologic and cytologic characteristics of 21 SNs and 21 nonsentinel nodes (NSNs) from melanoma patients who had clinically localized (AJCC Stage I--II) primary cutaneous melanoma. SNs showed highly significant reductions in total paracortical area and in the area of the paracortical subsector occupied by dendritic cells. The frequency of paracortical interdigitating dendritic cells (IDCs) was dramatically reduced in SNs, and most IDCs (approximately 99%) lacked the complex dendrites associated with active antigen presentation. The release of immunosuppressive factors from the primary melanoma may induce a localized and specific paralysis in the SN, which prevents the recognition of otherwise immunogenic melanoma antigens by IDCs. This immune paralysis may facilitate the implantation and growth of melanoma cells in the SN. Cytokine therapy may be able to reverse this immune paralysis. These findings have an important practical application in the histopathologic confirmation that a node is truly sentinel. They also offer an hypothesis to explain the failure of the immune surveillance mechanisms to identify and respond to a small primary melanoma that expresses immunogenic tumor antigens.

Recruitment of CD1a+ Langerhans cells to the nasal mucosa in seasonal allergic rhinitis and effects of topical corticosteroid therapy.

BACKGROUND: Local antigen presentation may be necessary for both primary and recall T-cell responses to grass pollen in hay fever patients. We examined the effect of seasonal allergen exposure on nasal mucosal antigen-presenting cell (APC) populations and the effects of topical corticosteroid therapy. METHODS: Nasal biopsies were collected from 46 grass pollen-sensitive seasonal rhinitis patients before the grass-pollen season. A second biopsy was collected during the pollen season, when patients had received 6 weeks' treatment with either fluticasone propionate (200 microg, twice daily) or placebo. Cell populations in biopsy sections were quantified by immunocytochemistry. RESULTS: Significant increases in submucosal and epithelial CD1a+ Langerhans cells, but not CD68 + macrophages or CD20 + B cells, were observed during the pollen season. Seasonal increases in CD1a+ Langerhans cells were inhibited by corticosteroid therapy. CONCLUSIONS: Recruitment of CD1a+ Langerhans cells to the nasal mucosa during natural seasonal allergen exposure may contribute to local T cell responses. Topical corticosteroids may act, at least in part, by inhibiting effective allergen presentation to T cells through inhibition of recruitment of Langerhans cells to the nasal mucosa.

Non-Hodgkin's lymphoma involving the vulva.

Non-Hodgkin's lymphomas (NHL) involving the vulva are rare. We report the clinicopathologic and immunohistochemical findings of six cases of vulvar NHL. The age of the patients ranged from 43 to 71 years (mean 60 years), and 5 presented with a vulvar mass. Two patients had neoplasms localized to the vulva, and two patients had a history of NHL that secondarily involved the vulva; in another patient the stage was unknown, and the sixth patient had stage IVA mycosis fungoides/Sezary syndrome involving the vulva. Each tumor was classified according to the revised European-American classification of lymphoid neoplasms: four were diffuse large B-cell lymphoma, one was peripheral T-cell lymphoma, and one was mycosis fungoides/Sezary syndrome. Two patients were treated with chemotherapy and radiotherapy, one patient received chemotherapy and phototherapy, one patient was treated with chemotherapy, and in two patients the treatment is unknown. Clinical follow-up, available for 4 cases, ranged from 7 months to 5 years. One patient with low-stage NHL responded to therapy, but relapsed and died of disease 2 years later. Two patients with generalized NHL that secondarily involved the vulva died of disease 7 months and 5 years, respectively, after the diagnosis of vulvar involvement was established. The patient with mycosis fungoides/Sezary syndrome is alive with disease at 4 years. The three patients in this study who died and our review of the literature indicate that NHL involving the vulva is usually an aggressive disease.