Novel Combination of Gallium Nitrate, Rituximab and Dexamethasone for the Treatment of Relapsed or Refractory Diffuse Large B-Cell Lymphoma, Mantle Cell Lymphoma or Transformed Follicular Lymphoma.

More than 56,000 new cases of non-Hodgkin’s lymphoma (NHL) will be diagnosed this year in the United States. Despite advances in treatment modalities such as radiation, biologic agents, and cytotoxic chemotherapeutic regimens, only 25–30% of these patients will be cured of their disease. Standard salvage regimens such as DHAP, ESHAP, ICE and EPOCH have proven efficacy at the cost of increasing toxicity and hospitalization costs. The reported response rates for these are on the order of 50–75% as first-line salvage regimens. However, as our aging patient population develops worsening performance status and co-morbidities, it seems appropriate to develop effective lymphoma treatments, which have fewer toxicities and lower costs for administration. One approach is to combine non-myelosuppressive therapies. One non-myelosuppressive agent, which has efficacy in lymphoma, is gallium nitrate. Investigation of gallium nitrate for cancer treatment dates back to the 1970’s. While it is currently approved for the treatment of bisphosphonate resistant hypercalcemia of malignancy, it has also been shown to inhibit ribonucleotide reductase and bind transferrin and potentially complex with the transferrin receptor, which is highly expressed in intermediate and aggressive histology lymphomas. It appears that the binding of the transferrin receptor on the lymphocyte as well as its inhibition of ribonucleotide reductase, eventually impairs iron metabolism, which is a necessary component of the intracellular cytochrome systems/mitochondrial function and ultimately oxidative phosphorylation.

The current study is a phase II clinical trial investigating the combination of gallium nitrate, rituximab and dexamethasone (GaRD) for relapsed or refractory DLBCL, MCL or transformed follicular lymphomas. The gallium nitrate is given at 200mg/m2 CIV days 1–7, rituximab 375mg/m2 IVPB day 1 and dexamethasone 40 mg po days 1–4. Eligible patients must have proven relapsed or refractory disease and have a SWOG PS <3. Patients may have failed prior ASCT or allogeneic SCT. The accrual goal is 37 patients. We have enrolled 14 patients on study to date and have 12 evaluable patients; as part of the ongoing safety evaluation for this study, we have the following results: ORR 9/12 (75%); CR 2/12 (17%); PR 7/12 (58%); SD 2/12 (17%); and PD 1/12 (8%). Most of these patients were refractory to prior salvage regimens 8/12 (67%), including ESHAP, DHAP or high-dose cyclophosphamide. No patients developed grade 3 or 4 toxicities, with the exception of grade 4 lymphopenia and grade 3 anemia (most likely due to transferrin receptor binding).

Conclusions: gallium nitrate, rituximab and dexamethasone (GaRD) appears to be an effective and relatively non-toxic salvage regimen for patients with relapsed DLBCL, MCL or transformed FL.