Marybeth Nelson

Immunologic and clinical effects of antibody blockade of cytotoxic T lymphocyte-associated antigen 4 in previously vaccinated cancer patients

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) functions as a negative regulator of endogenous and vaccine-induced antitumor immunity. The administration of fully human anti-CTLA-4 blocking monoclonal antibodies to advanced-cancer patients increases immune-mediated tumor destruction in some subjects. Nonetheless, patients that respond also frequently manifest serious inflammatory pathologies, raising the possibility that the therapeutic and toxic effects of CTLA-4 blockade might be linked. Here we show that periodic infusions of anti-CTLA-4 antibodies after vaccination with irradiated, autologous tumor cells engineered to secrete GM-CSF (GVAX) generate clinically meaningful antitumor immunity without grade 3 or 4 toxicity in a majority of metastatic melanoma patients. The application of this sequential immunotherapy to advanced ovarian carcinoma patients also revealed that tumor destruction and severe inflammatory pathology could be dissociated, although further refinements are required to increase clinical responses and to minimize toxicity in this population. The extent of therapy-induced tumor necrosis was linearly related to the natural logarithm of the ratio of intratumoral CD8+ effector T cells to FoxP3+ regulatory T cells (Tregs) in posttreatment biopsies. Together, these findings help clarify the immunologic and clinical effects of CTLA-4 antibody blockade in previously vaccinated patients and raise the possibility that selective targeting of antitumor Tregs may constitute a complementary strategy for combination therapy.

Primary Therapy of Waldenström Macroglobulinemia With Bortezomib, Dexamethasone, and Rituximab: WMCTG Clinical Trial 05-180

PURPOSE We examined the activity of bortezomib, dexamethasone, and rituximab (BDR) in patients with symptomatic, untreated Waldenström macroglobulinemia (WM). PATIENTS AND METHODS A cycle of therapy consisted of bortezomib 1.3 mg/m(2) intravenously; dexamethasone 40 mg on days 1, 4, 8, and 11; and rituximab 375 mg/m(2) on day 11. Patients received four consecutive cycles for induction therapy and then four more cycles, each given 3 months apart, for maintenance therapy. Twenty-three patients received a median of seven cycles of treatment. RESULTS Median bone marrow disease involvement declined from 55% to 10% (P = .0004), serum immunoglobulin M levels declined from 4,830 to 1,115 mg/dL (P < .0001), and hematocrit increased from 29.8% to 38.2% (P = .0002) at best response. The overall response rates and major response rates were 96% and 83% with three complete responses, two near complete responses, three very good partial responses, 11 partial responses, and three minor responses. Responses occurred at a median of 1.4 months. With a median follow-up of 22.8 months, 18 of 23 patients remained free of disease progression. Peripheral neuropathy was the most common toxicity, and it resolved to grade < or = 1 in 13 of 16 patients at a median of 6.0 months. Four of the first seven treated patients developed herpes zoster, resulting in the institution of prophylactic antiviral therapy. CONCLUSION The results demonstrate that BDR produces rapid and durable responses, along with high rates of response and complete remissions in WM. Herpes zoster prophylaxis is necessary with BDR, and reversible peripheral neuropathy was the most common toxicity leading to premature discontinuation of bortezomib in 61% of patients. Exploration of alternative schedules for bortezomib administration that includes weekly dosing should be pursued.

Serum immunoglobulin free light chain correlates with tumor burden markers in Waldenstrom macroglobulinemia.

The serum IgM level has been utilised as a marker of tumor progression and to assess response to therapy in patients with Waldenstrom macroglobulinemia (WM). However, there are many limitations to the IgM protein level. The objective of this study was to evaluate the association of known tumor burden markers and prognostic factors with serum free light chain (sFLC) in 98 patients with WM. We demonstrated that sFLC measurement accurately differentiated IgM-MGUS compared with WM reflecting a measurement of tumor burden. In univariate and multivariate analysis, median sFLC at the cut-off at 60 mg/L was higher for WM patients with low hemoglobin and high β2M, when we applied the WM-IPSS cut-offs, but showed no association with IgM level. This study demonstrates that sFLC is a new marker in WM disease. Further analysis is required to prospectively study the role of sFLC in monitoring response to therapy and as a prognostic marker in WM patients.