Changing paradigms in the treatment of chronic lymphocytic leukemia

Progress in our understanding of chronic lymphocytic leukemia and its treatment has resulted in a more tailored approach to patient management, with different therapeutic regimens for different patient populations. The current standard of care has evolved from single-agent therapy with chlorambucil or cyclophosphamide, through the introduction of purine analogs to the more recent introduction of chemoimmunotherapy. Selection of appropriate initial therapy should be based primarily on patient characteristics such as age, performance status and the expected clinical course of the leukemia based on established risk factors. Achieving a complete and durable response is the major goal for fit patients; chemoimmunotherapy with fludarabine, cyclophosphamide and rituximab would be advantageous. Alternatively, in unfit patients, controlling symptoms is the essential treatment goal and a regimen with a more favorable toxicity profile should be applied. This manuscript reviews the data that has lead to current treatment choices, advises on tailored therapies and discusses emerging trends. Data for this review was identified by a search of electronic information including Medline and PubMed databases, conference proceedings and trial registers. Critical analysis of extracted data was undertaken with attention to trial phase, treatment schedules and end points, including response rates, follow-up times, progression-free survival and overall survival.

Phase II study of short course CHOP-rituximab (R) followed by ibritumomab tiuxetan (IT) as first-line treatment for follicular lymphoma (FL)

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Background: Therapy with CHOP-R and radioimmunotherapy (RIT) is a promising treatment for untreated FL. Press reports complete responses (CR) of 69% in FL patients (pts.) with 6 cycles of CHOP followed by I-131 tositumomab. We report efficacy and safety using 3 cycles of CHOP-R followed by IT and extended R. Methods: Eligibility criteria include symptomatic or grade 3 untreated FL. 60 pts. have been accrued and 47 evaluated. The treatment consists of two phases: CHOP-R for 3 cycles followed by IT. One week after IT, pts receive R weekly × 4. Bone marrow (BM) biopsies and fusion PET-CT scans are obtained at baseline, after CHOP-R, and 12 weeks post RIT. The primary endpoint is CR rate. CR requires a neg. PET scan and conventional Working Group criteria. Results: Toxicity data are available for 47 pts of median age 56 (range, 39–78), 44 of whom completed both phases of therapy and are evaluated for response. Characteristics and CR rates after IT are shown: 3 pts. did not receive RIT (1 second malignancy, 1 non-compliance, 1 septic death). Of the 44, CR after CHOP-R is 41%. After IT, CR improved to 89%. Of the 5 pts who did not achieve CR, 3 had neg. PET scans (2 with PR, 1 with SD by CT), and 2 had residual disease by PET with PR by CT. At a mean follow-up of 16 months (range, 6–33 months), there are 4 relapses: 3 who achieved CR by PET-CT, 1 with PR by PET-CT. Toxicity was predominantly myelosuppression. There was 1 episode of febrile neutropenia after RIT. Conclusions: 3 cycles of CHOP-R followed by IT and R achieve a high CR in previously-untreated pts. with FL. Addition of RIT increased CR from 41% to 89%. Data will be presented on the affect of bulky disease, positive BM, grade 2 or 3 histology, and high FLIPI score on CR. Further follow-up is necessary to evaluate response duration and determine whether there is a correlation with early or late CR.

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Imaging results after CHOP-rituximab followed by 90Y ibritumomab tiuxetan and rituximab (R) in patients with previously-untreated follicular lymphoma (FL)

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Background: There has been some question regarding the predictive value of 111In scans in FL. We report imaging results with fusion PET-CT scans and 111In scans in a single-institution, non-randomized, phase II trial in patients with FL treated with CHOP-R followed by 90Y ibritumomab tiuxetan (Zevalin (Z)) and R. Methods: Eligible patients have CD20 positive FL, Grade 1–3 or transformed, Stage II-IV, no prior treatment with monoclonal antibody or chemotherapy, and symptomatic disease (if grade 1–2). CHOP-R is given every 21 days for 3 cycles. Four weeks after the last dose of CHOP-R, patients receive the Zevalin regimen, which includes 111In imaging and 90Y therapy. One week after Z, patients receive R 375 mg/m2 IV weekly for 4 doses. Bone marrow examination and fusion PET-CT scans are performed at baseline, after CHOP-R, and 12 weeks after Z. The primary endpoint is CR, and responses are reported using the International Working Group (IWG) criteria with the additional requirement of a negative PET scan for CR/CRu. Results: Thirty-six FL patients have been accrued, and 16 patients have completed therapy and follow-up studies. One patient did not have a positive PET scan at baseline. Following therapy, the proportion with a negative PET scan improved from 8 of 15 (53.3%) after CHOP-R to 15 of 15 (100%) after Z. Using IWG criteria in combination with PET scan results, the CR rate increased from 4 of 15 (26.7%) after CHOP-R to 12 of 15 (80%) after Z. Five of 6 patients (83%) with tumor uptake by 111In scan and 7 of 9 (78%) with a 111In scan negative for tumor achieved a CR. Conclusions: There was no significant difference in CR between those patients with 111In tumor uptake versus patients with a negative 111In scan. Functional imaging with PET-CT may be a more sensitive method than CT alone in determining residual disease in FL. This trial continues to accrue patients, and more time is needed to determine the duration of response and time to next therapy.

No significant financial relationships to disclose.

Early results of modified fludarabine, cyclophosphamide, and rituximab (mFCR) for patients with previously untreated advanced chronic lymphocytic leukemia (CLL)

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Background: Recent data reporting results of FCR therapy in previously untreated advanced CLL patients (F-25 mg/m2 d1–3 q 4wk; C-250 mg/m2 d 1–3 q 4wk; R-500 mg/m2 d1 q 4wk for 6 cycles) demonstrated complete remission (CR) of 70% and overall response (OR) of 95% (J Clin Oncol 2005;23:4079). The major toxicity was grade 3/4 neutropenia during 52% of courses. One approach to decrease neutropenia without compromising efficacy could be by reducing the doses of F and C and increasing the dose of R as high-dose R has been reported to be more efficacious in CLL. Methods: We conducted a phase II study for previously untreated advanced CLL patients treated with mFCR (F-20mg/m2 d1–3 q 4 wk; C-150 mg/m2 d1–3 q 4 wk; R-500mg/m2 d1 and d14 q 4wks; maintenance R-500 mg/m2 q 3 months until progression). A Simon two-stage design was used where 15 patients were accrued in the first stage and because of acceptable toxicity and response rate in stage I an additional 35 patients will be treated. The primary endpoint was response rate. Results: Twenty patients (13 male, 7 female), age 36–85 years (median 59) were treated with a total of 105 mFCR courses. All 20 patients were evaluable for toxicity. Grade 3/4 neutropenia occurred during 11(10.5%) courses. There were no episodes of neutropenic fever. Grade 3/4 thrombocytopenia occurred during 4 (3.8%) courses. Two patients are currently on study and not evaluable for response and among the 18 evaluable patients, the CR was 68%, PR was 32% with an OR of 100%. Eleven of the 12 CR patients had no evidence of CD5+/CD19+ coexpressing cells in their bone marrow after therapy and one had <1%; all 12 were NED by CT scan. Conclusions: Our preliminary results suggest mFCR is highly effective with considerably less grade 3/4 neutropenia than standard FCR. Complete responders had minimal residual disease in their bone marrow following mFCR.

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Cyclophosphamide followed by fludarabine for untreated chronic lymphocytic leukemia: a phase II SWOG TRIAL 9706

B-cell chronic lymphocytic leukemia (CLL) accounts for 95% of chronic leukemia cases and 25% of all leukemia. Despite the prevalence of CLL, progress in its treatment has been only modest over the past three decades. Based upon the ability of fludarabine to produce high-grade remissions especially among patients with low initial tumor mass, and the ability of alkylators to reduce tumor mass, we hypothesized that sequential administration of a limited number of cycles of intermediate-dose cyclophosphamide followed by fludarabine could result in a larger percentage of patients with complete remissions (CRs). In all, 27 of the 49 eligible patients achieved overall responses of CR, unconfirmed complete remission (UCR), or PR, for a total response rate of 55% (95% confidence interval (CI) 40-69%). Considering the confounding medical issues of this patient population with advanced aggressive disease, the regimen was generally well tolerated. This study demonstrates that high-dose cyclophosphamide followed by fludarabine was relatively well tolerated in this group of advanced CLL patients. The study's criterion for testing whether the regimen is sufficiently effective to warrant further investigation was met: 14 (32%) of the first 44 eligible patients achieved CR or UCR.

Gene therapy for head and neck cancer using vaccinia virus expressing IL-2 in a murine model, with evidence of immune suppression

We evaluated the efficiency of recombinant vaccinia virus expressing interleukin-2 (rvv-IL-2) as a tumor vaccine in an immunocompetent mouse model of head and neck squamous cell carcinoma (SCC VII/SF). Mice with five-day-old tumors in the floor of the mouth were treated with rvv-IL-2 by intratumoral injections. These treated mice survived longer (P <.03) than mice treated with control vaccines. Splenocytes, bone marrow, and lymph node cells from tumor-bearing mice responded poorly to concanavalin A stimulation, suggesting induction of immunosuppression. The rvv-IL-2 virus grew for 7 days in the tumor following intratumoral injection. We did not detect any virus particles in several normal organs following rvv-IL-2 injection. Comparison of expression levels of several potential immune inhibitory mediators between the tumors growing in mice and cultured tumor cells demonstrated higher expression of IL-10, GM-CSF, TGF-beta, and NO synthetase in tumors. These results suggested possible roles for these molecules in immunosuppression. We conclude that rvv-IL-2 has potential as a therapeutic vaccine for head and neck cancer and that it can be more effective provided the immunosuppression is reversed.

Interim analysis of the use of the anti-idiotype breast cancer vaccine 11D10 (TriAb) in conjunction with autologous stem cell transplantation in patients with metastatic breast cancer

The anti-idiotype monoclonal antibody breast cancer vaccine 11D10 (TriAb) was administered before and after autologous stem cell transplantation (ASCT) in 45 patients with metastatic breast cancer whose disease was responsive to conventional chemotherapy. Evidence of a positive anti-anti-idiotype antibody (Ab3) humoral response was noted at a median of 1.76 months post-ASCT (range, before ASCT-6 months) with this strategy. Maximal Ab3 levels and idiotype-specific T-cell proliferative responses were observed at a median of 3 and 4 months, respectively, after ASCT. The achievement of rapid immune responses after ASCT, during a known period of decreased immunoresponsiveness, opens the possibility of an additional antitumor effect at a time when the tumor burden is relatively small. Moreover, in this interim analysis, patients with the most vigorous humoral and cellular immune responses had a significant improvement in progression-free survival. Further follow-up and evaluation of this approach is warranted.

Murine monoclonal anti-idiotypic antibody as a surrogate antigen for human Her-2/neu

The anti-idiotypic (Id) monoclonal antibody (MAb) 520C9-6b (IgG1k), raised in syngenic mice against the murine anti-Her2/neu MAb 520C9 (Ab1), functionally mimics a human Her2/neu epitope and serves as a surrogate for the protein antigen. Immunization of allogeneic C57BL/6 mice and rabbits with 520C9-6b (Ab2) induced anti-Her2/neu-specific antibodies that react with antigen-positive SKBr3 cells by ELISA and FACS analysis. The immune sera inhibited binding between Ab1 and Ab2 and vice versa (binding of Ab2 to Ab1), indicating that it was a true anti-anti-Id (Ab3) antibody. The Ab3 sera or purified Ab3 specifically lysed Her2/neu-positive SKBr3 cells, but no significant lysis was observed in antigen-negative LS174T cells in an antibody-dependent cellular cytotoxicity assay. An Id-specific cellular immune response was also demonstrated in an in vitro lymphocyte proliferation assay. Furthermore, a panel of tumor tissues and tumor cells was screened for the presence of the Her2/neu epitope by its reactivity with Ab1 and Ab3 using immunohistochemistry and FACS analysis. Identical results were obtained using either Ab1 or Ab3 (Ab1'). The data indicated that anti-Id 520C9-6b can induce Her2/neu-specific antibody in experimental animals and may serve as a potential network antigen for the treatment of patients bearing Her2/neu-positive tumors.

Adjuvant immunotherapy for melanoma and colorectal cancers

Immune approaches to the therapy of colorectal cancer and melanoma have substantially evolved over the past years, from treating patients with nonspecific immune stimulants to a focus on the use of tumor-associated antigens (TAAs) either by passive immune therapy with antibodies targeted directly to tumor cells or by active immune therapy via vaccination with tumor cells, tumor cell lysates, peptides, carbohydrates, gene constructs encoding proteins, or anti-idiotype antibodies that mimic TAAs. We review the different immunotherapeutic approaches to the treatment of melanoma and colorectal cancers, and summarize relevant clinical trials.

Immunotherapy for colorectal cancer

Immunologic approaches to therapy for colorectal cancer have evolved substantially. In the past, patients were treated with nonspecific immune stimulants such as bacillus Calmette-Guérin (BCG). The current focus lies in targeting tumor-associated antigens. This is done either through passive immune therapy, with antibodies targeted directly to tumor cells, or by active immune therapy through vaccination with tumor cells, tumor cell lysates, peptides, carbohydrates, gene constructs encoding proteins, or anti-idiotype antibodies that mimic tumor-associated antigens. These different approaches to immunotherapy are reviewed.

Adjuvant immunotherapy for melanoma and colorectal cancers

Immune approaches to the therapy of colorectal cancer and melanoma have substantially evolved over the past years, from treating patients with nonspecific immune stimulants to a focus on the use of tumor-associated antigens (TAAs) either by passive immune therapy with antibodies targeted directly to tumor cells or by active immune therapy via vaccination with tumor cells, tumor cell lysates, peptides, carbohydrates, gene constructs encoding proteins, or anti-idiotype antibodies that mimic TAAs. We review the different immunotherapeutic approaches to the treatment of melanoma and colorectal cancers, and summarize relevant clinical trials.

The anti-idiotype vaccines for immunotherapy

Certain anti-idiotypic antibodies that bind to the antigen-combining sites of antibodies can effectively mimic the three-dimensional structures and functions of the external antigens and can be used as surrogate antigens for active specific immunotherapy. Extensive studies in animal models have demonstrated the efficacy of these vaccines for triggering the immune system to induce specific and protective immunity against bacterial, viral and parasitic infections as well as tumors. Several monoclonal anti-idiotype antibodies that mimic distinct human tumor-associated antigens have been developed and characterized. Encouraging results have been obtained in recent clinical trials using these anti-idiotype antibodies as vaccines. In this article, we will review the current literature and discuss the potential of this novel therapeutic approach for various human cancers.

Construction and characterization of DNA vaccines encoding the single-chain variable fragment of the anti-idiotype antibody 1A7 mimicking the tumor-associated antigen disialoganglioside GD2

Anti-idiotype antibody, 1A7, functionally mimics the tumor-associated antigen disialoganglioside GD2, which is overexpressed on the surface of a number of neuroectodermal tumors such as melanoma, neuroblastoma, soft tissue sarcoma, and small cell carcinoma of the lung. Immunization of mice with 1A7 generated the production of anti-GD2 antibodies. In a phase I clinical trial, immunization of patients with 1A7, mixed with the adjuvant QS21, demonstrated that 1A7 could act as a surrogate antigen for GD2 and induce strong humoral immune responses in advanced stage melanoma patients. DNA vaccines have recently been shown to invoke humoral as well as cellular responses in injected hosts against the transgene product. To evaluate the efficiency of DNA vaccines encoding anti-idiotype antibodies, we constructed expression plasmids encoding the variable heavy (VH) and variable light (VL) chains of 1A7. The plasmids were made in two configurations, expressing either the VH (pc1A7VHLnVL) or the VL (pc1A7VLLnVH) chain of 1A7 at the amino terminus, linked together by a 15-amino acid linker (Ln). In vitro transcription/translation assays and transfection of CHO-K1 cells with the plasmids demonstrated that a approximately 30-kDa protein was expressed by both configurations of the single-chain variable fragment. This protein can be specifically precipitated by monoclonal anti-GD2 antibody, 14G2a. Following intramuscular injection in mice, the plasmids were detectable in the injected tissues for at least 3 months and the injected plasmids actively transcribed the single-chain variable fragment 1A7 gene at the injected site. A single, intramuscular immunization of a group of C57BL/6 mice with pc1A7VLLnVH in phosphate-buffered saline induced humoral immune responses against 1A7 as well as GD2, the nominal antigen. Multiple immunizations, however, were required to elicit stronger immune responses.

Use of the anti-idiotype antibody vaccine TriAb after autologous stem cell transplantation in patients with metastatic breast cancer

Between April 1997 and March 1998 we evaluated the immune response and outcome in 11 chemosensitive patients who were treated with the anti-idiotype antibody vaccine TriAb after recovery from intensive therapy and autologous stem cell transplant (ASCT). Triab was commenced after recovery from the acute effects of ASCT; a minimum interval of 1 month was required from completion of consolidation radiotherapy, if given. Nine patients (82%) manifest anti-anti-idiotype antibody (Ab3) responses post ASCT. The maximal Ab3 response was seen after a median of 10 doses (range 5-20), which corresponded to a median of 14 months (range 5-19) post ASCT. Evidence of a T cell proliferative response was seen in eight patients; the response was modest in most of these. At a median follow-up of 24 months (range 22-33) after ASCT, four patients are alive without evidence of disease progression. All four of these patients were in the subgroup with more vigorous immune responses. Subsequent efforts have been directed toward the achievement of higher levels of immune responses more rapidly post ASCT. Bone Marrow Transplantation (2000) 26, 729-735.

Anti-idiotype vaccine against cancer

Immunization with anti-idiotype (Id) antibodies represents a novel new approach to active immunotherapy. Extensive studies in animal tumor models have demonstrated the efficacy of anti-Id vaccines in preventing tumor growth and curing mice with established tumor. We have developed and characterized several murine monoclonal anti-Id antibodies (Ab2) which mimic distinct human tumor-associated antigens (TAA) and can be used as surrogate antigens for triggering active anti-tumor immunity in cancer patients. Encouraging results have been obtained in recent clinical trials. In this article, we will review the existing literature and summarize our own findings showing the potential of this approach for various human cancers. We will also discuss where anti-Id vaccines may perform better than traditional antigen vaccines.

Monoclonal antibody therapies for lymphomas

Important advances in molecular biology and chelation chemistry have led to new and improved monoclonal antibody reagents. Rituximab (IDEC-C2B8) was approved by the United States Food and Drug Administration for relapsed CD20-positive lymphomas, and denileukin diftitox was approved (DAB389IL-2) for CTCL. Ibritumomab tiuxetan and iodine 131 anti-B1 have excellent activity and acceptable toxicity and likely higher responses than rituximab. These questions should be answered in phase III trials, and preliminary results from the rituximab versus ibritumomab tiuxetan trial suggest higher responses to the latter. Data on radiolabeled Lym-1, T101, LL2, and anti-Tac also look promising. The therapeutic role of immunotoxins has yet to be determined, but encouraging data with DAB389IL-2 and LMB-2 have been reported. Antibody conjugates with drugs, prodrugs, nonprotein toxins, and other agents are also under investigation. Bispecific antibodies for lymphoma may also have a future role in lymphoma therapy. It is anticipated that many of the major advances in lymphoma therapy will be antibody based.

Clinical and immune responses in advanced melanoma patients immunized with an anti-idiotype antibody mimicking disialoganglioside GD2

PURPOSE

To determine immune responses and toxicity to the anti-idiotype vaccine, as well as clinical responses and survival, we initiated a clinical trial for patients with advanced melanoma treated with an anti-idiotype antibody (TriGem) that mimics the disialoganglioside GD2.

PATIENTS AND METHODS

Forty-seven patients with advanced melanoma received either 1-, 2-, 4-, or 8-mg doses of TriGem (Titan Pharmaceuticals Inc, South San Francisco, CA) mixed with QS-21 adjuvant (Aquila Biopharmaceuticals, Inc, Worcester, MA) 100 microg subcutaneously weekly for 4 weeks and then monthly until disease progression. Median age was 57 years, there were 32 men and 15 women, 43% of patients had undergone prior therapy for metastatic disease, 55% had disease confined to soft tissue, and 45% had visceral metastasis.

RESULTS

Hyperimmune sera from 40 of 47 patients showed an anti-anti-idiotype (Ab3) response. Patient Ab3 was truly Ab1' because it specifically bound purified disialoganglioside GD2. The isotypic specificity of the Ab3 antibody consisted of predominantly immunoglobulin (Ig)G, and all IgG subclasses were represented. One patient had a complete response that persisted at 24 months, and 12 patients were stable from 14+ to 37+ months (median, 18+ months). Disease progression occurred in 32 patients on study from 1 to 17 months (median, 5.5 months), and 21 have died at 1 to 16 months (median, 6 months). The Kaplan-Meier-derived overall median survival has not been reached. Median survival has not been reached for the 26 patients with soft tissue disease only and was 13 months for 21 patients with visceral metastasis. Toxicity consisted of local reaction at the site of injection and mild fever and chills.

CONCLUSION

TriGem has minimal toxicity and generates robust and specific IgG immune responses against GD2. Objective responses were minimal, but there may be a favorable impact on disease progression and survival that will require prospective randomized trials.

Clinical and immune responses in resected colon cancer patients treated with anti-idiotype monoclonal antibody vaccine that mimics the carcinoembryonic antigen

PURPOSE

We generated an anti-idiotype antibody, designated CeaVac, that is an internal image of the carcinoembryonic antigen (CEA). We previously demonstrated that the majority of patients with advanced colorectal cancer generate specific anti-CEA responses. The purpose of the current study was to treat patients with surgically resected colon cancer with CeaVac to determine the immune response and clinical outcome to treatment with vaccine. We also compared the immune responses between patients treated with fluorouracil (5-FU) chemotherapy regimens plus vaccine versus vaccine alone.

PATIENTS AND METHODS

Thirty-two patients with resected Dukes' B, C, and D, and incompletely resected Dukes' D disease were treated with 2 mg of CeaVac every other week for four injections and then monthly until tumor recurrence or progression. Fourteen patients were treated concurrently with 5-FU chemotherapy regimens.

RESULTS

All 32 patients entered onto this trial generated high-titer immunoglobulin G and T-cell proliferative immune responses against CEA. The 5-FU regimens did not have a qualitative or quantitative effect on the immune response. Three of 15 patients with Dukes' B and C disease progressed at 19, 24, and 35 months. Seven of eight patients with completely resected Dukes' D disease remained on study from 12 to 33 months; one patient with resected Dukes' D disease relapsed at 9 months. One patient with incompletely resected Dukes' D disease remained on study at 14 months without evidence of progression; eight experienced disease progression at 6 to 31 months.

CONCLUSION

CeaVac consistently generated a potent anti-CEA humoral and cellular immune response in all 32 patients entered onto this trial. A number of very high-risk patients continue on study. 5-FU regimens, which are the standard of care for patients with Dukes' C disease, did not affect the immune response. These data warrant a phase III trial for patients with resected colon cancer.

Construction and characterization of a chimeric fusion protein consisting of an anti-idiotype antibody mimicking a breast cancer-associated antigen and the cytokine GM-CSF

Anti-idiotype antibody, 11D10 mimics biologically and antigenically a distinct and specific epitope of the high molecular weight human milk fat globule (HMFG), a cancer-associated antigen present in over 90% of breast tumor samples. To augment the immunogenicity of 11D10 without the aid of a carrier protein or adjuvant, we made a chimeric 11D10-GM-CSF fusion protein for use as a vaccine. An expression plasmid for 11D10 was made by ligation of the DNA sequences of the 11D10 light-chain variable region upstream of the human kappa constant region. The heavy-chain plasmid carrying GM-CSF was made by ligation of the heavy-chain variable region sequences upstream of the human gamma1 constant region CH1 fused to the DNA fragment encoding the mature GM-CSF peptide 3' to the CH3 exon. NS1 plasmacytoma cells were transfected with the light and heavy-chain vectors by electroporation. Fusion protein secreted in the culture medium was purified and was characterized by gel electrophoresis as well as by determination of the biological activity of the fused GM-CSF. In nonreducing SDS-polyacrylamide gels, a single band approximately 200 Kd reacted with anti-human kappa, anti-human lambda1 and anti-GM-CSF antibodies. In reducing polyacrylamide gels, a approximately 74 kd protein reacted with anti-human lambda1 and anti-GM-CSF antibodies. The fusion protein induced proliferation of GM-CSF dependent NFS-60 cells. These results suggest that the protein is a chimeric anti-idiotype antibody consisting of 11D10 variable domains, human kappa and lambda1 constant domains and that the GM-CSF moiety fused to the constant region lambda1 is biologically active.

Postoperative radiotherapy in the treatment of single metastases to the brain: a randomized trial

CONTEXT

For the treatment of a single metastasis to the brain, surgical resection combined with postoperative radiotherapy is more effective than treatment with radiotherapy alone. However, the efficacy of postoperative radiotherapy after complete surgical resection has not been established.

OBJECTIVE

To determine if postoperative radiotherapy resulted in improved neurologic control of disease and increased survival.

DESIGN

Multicenter, randomized, parallel group trial.

SETTING

University-affiliated cancer treatment facilities.

PATIENTS

Ninety-five patients who had single metastases to the brain that were treated with complete surgical resections (as verified by postoperative magnetic resonance imaging) between September 1989 and November 1997 were entered into the study.

INTERVENTIONS

Patients were randomly assigned to treatment with postoperative whole-brain radiotherapy (radiotherapy group, 49 patients) or no further treatment (observation group, 46 patients) for the brain metastasis, with median follow-up of 48 weeks and 43 weeks, respectively.

MAIN OUTCOME MEASURES

The primary end point was recurrence of tumor in the brain; secondary end points were length of survival, cause of death, and preservation of ability to function independently.

RESULTS

Recurrence of tumor anywhere in the brain was less frequent in the radiotherapy group than in the observation group (9 [18%] of 49 vs 32 [70%] of 46; P<.001). Postoperative radiotherapy prevented brain recurrence at the site of the original metastasis (5 [10%] of 49 vs 21 [46%] of 46; P<.001) and at other sites in the brain (7 [14%] of 49 vs 17 [37%] of 46; P<.01). Patients in the radiotherapy group were less likely to die of neurologic causes than patients in the observation group (6 [14%] of 43 who died vs 17 [44%] of 39; P=.003). There was no significant difference between the 2 groups in overall length of survival or the length of time that patients remained functionally independent.

CONCLUSIONS

Patients with cancer and single metastases to the brain who receive treatment with surgical resection and postoperative radiotherapy have fewer recurrences of cancer in the brain and are less likely to die of neurologic causes than similar patients treated with surgical resection alone.

Antigen mimicry by an anti-idiotypic antibody single chain variable fragment

For the therapy of cancer patients whose disease is positive for Carcinoembryonic Antigen (CEA), we developed an active specific immunotherapy based on the idiotypic network. The anti-idiotype monoclonal antibody (mAb), 3H1 was generated by immunization of mice with the anti-CEA mAb, 8019. 3H1 mimics CEA both functionally and structurally and acts as a surrogate for CEA. To define the minimum structural requirements for antigen mimicry by 3H1, we constructed plasmid vectors for expression of single chain Fv (scFv) variants of 3H1 in Escherichia coli. Variable heavy (VH) and variable light (VL) chain domains of 3H1 were linked by a 15 amino acid linker (Ln), (Gly4Ser)3 in two constructs, VH-Ln-VL and VL-LnVH. Ln was omitted in two constructs, VH-VL and VL-VH. Each of the scFv constructs has a tag of six His [(His)6 tag] for purification by metal chelate affinity chromatography and detection by enzyme-linked immunoabsorbent assay (ELISA). Comparisons of the binding of 8019 to purified scFv proteins by ELISA and immunoblot experiments showed that only VH-Ln-VL had significant activity. VH-Ln-VL also showed maximum inhibition of binding of 8019 to CEA. Immunization of mice with naked VH-Ln-VL and VH-Ln-VL conjugated to keyhole limpet hemocyanin induced anti-CEA antibodies in mouse sera. Sera from immunized mice inhibited the binding of 8019 to 3H1 as well as CEA. Induction of anti-CEA antibodies in the immunized mice was confirmed by flow cytometric analysis using CEA positive MC-38cea cells. These results demonstrate that for antigen mimicry of 3H1 scFv, the presence of Ln is necessary and the domain order should be VH followed by VL.

Antibody responses in melanoma patients immunized with an anti-idiotype antibody mimicking disialoganglioside GD2

We initiated a clinical trial for patients with advanced malignant melanoma treated with an anti-idiotype antibody that mimics the disialoganglioside GD2. We report the clinical and immune responses of the first 12 patients entered into this trial. Patients received 1-, 2-, 4-, or 8-mg doses of the anti-idiotype antibody mixed with 100 microg of QS-21 adjuvant every other week, four times, and then monthly. Twelve patients have been on trial for 2-23 months, and all of them have generated immune responses. Patients were removed from the study if they demonstrated disease progression. Hyperimmune sera from all 12 patients revealed an anti-anti-idiotypic Ab3 response, as demonstrated by the inhibition of Ab2 binding to Ab1 by patients' immune sera. To further test the anti-anti-idiotypic response, patients' Ab3 antibodies were affinity purified on Sepharose 4B columns containing adsorbed immunizing anti-idiotype immunoglobulin. Purified Ab3 of all patients studied inhibited binding of Ab1 to a GD2-positive cell line. Purified Ab3 also inhibited binding of Ab1 to purified GD2, in a manner comparable to equal quantities of purified Ab1. The patient Ab3 was truly an Ab1' because it specifically bound to purified disialoganglioside GD2. The isotypic specificity of the Ab3 antibody was predominantly IgG, with only minimal IgM. The predominant IgG subclass was IgG1, with approximately equal quantities of IgG2, IgG3, and IgG4. These Ab3 antibodies reacted specifically with tumor cells expressing GD2 by immune flow cytometry and immunoperoxidase assays. Five patients' Ab3 antibodies studied for antibody-dependent cellular cytotoxicity were positive. One patient had a complete clinical response, with resolution of soft tissue disease, and six patients had stable disease, ranging from 9 to 23 months, and are being continued on vaccine therapy. Toxicity consisted of local reaction at the site of the injection, including induration and pain that generally resolved within a few days. Mild fever and chills were observed in 75% of the patients but rarely required acetaminophen. There was no additional toxicity, including abdominal pain that was previously seen with infusion of murine monoclonal anti-GD2 antibody. Current trials include patients with stage III melanoma and small cell lung cancer. Future trials will attempt to enhance the antitumor response by the addition of interleukin 2, granulocyte macrophage colony-stimulating factor, and other cytokines, together with the 1A7 vaccine.

Molecular mimicry of carcinoembryonic antigen by peptides derived from the structure of an anti-idiotype antibody

Our goal was to use carcinoembryonic antigen (CEA) as a target for immunotherapy in CEA-positive cancer patients who are all immune tolerant to the native antigen. We isolated and characterized an anti-idiotype monoclonal antibody 3H1, which mimics a distinct and specific epitope of the Mr 180,000 CEA and can be used as a surrogate for CEA. In Phase Ib clinical trials in a group of 23 advanced colorectal cancer patients, 3H1 induced both humoral and cellular anti-3H1 responses, as well as anti-CEA immunity. To study the cellular immunity invoked by 3H1 at the molecular level, we have cloned and sequenced the cDNAs encoding the variable heavy and light chains of 3H1 and deduced the amino acid sequences of the encoded proteins. To identify any cross-reactive peptides of 3H1 and CEA, we compared the amino acid sequences of 3H1 with those of CEA and found several regions of homology in 3H1 heavy and light chain variable domains, as well as in the framework regions. To search for potential cross-reactive T-cell epitopes, a number of peptides were synthesized based on 3H1/CEA homology and were used as stimulants in cell proliferation assays, using peripheral blood mononuclear cells from a group of 3H1-immunized CEA-positive cancer patients in the adjuvant setting. Two partially homologous peptides, designated LCD-2 (from 3H1) and CEA-B (from CEA), were identified in 10 of 21 adjuvant patients by strong proliferation responses (stimulation index, 3-50-fold), which were extensively studied in five of these individuals over an extended period of time (12-24 months). We saw no correlation with the MHC class I haplotype of the patients. Analysis of the subtype of the responding T cells demonstrated that primarily CD4+ T cells were stimulated by both 3H1 and 3H1-derived peptides. Interleukin 2, interleukin 4, and IFN-gamma were assayed in the culture medium of peripheral blood mononuclear cells stimulated with 3H1, CEA, and LCD-2 to determine the T-cell helper subset induced by these stimulants. The in vitro responses were mainly associated with secretion of IFN-gamma, which suggested that the induced T cells were most likely CD4+ Th1 type. Future studies will include the design of second-generation LCD-2 and CEA peptides to further enhance antigenicity, to characterize the responding T-cell populations more fully, and to test refined peptides for immunogenicity.

Induction of IgG antibodies by an anti-idiotype antibody mimicking disialoganglioside GD2

The anti-idiotype (Id) monoclonal antibody (mAb) 1A7 immunoglobulin G1 (IgG1, kappa), raised in syngeneic mice against the murine anti-ganglioside GD2 mAb 14G2a mimics a carbohydrate epitope on GD2 and serves as a surrogate protein antigen for this disialoganglioside. Immunization of allogeneic C57BL/6 mice and rabbits with 1A7 induced anti-GD2 antibodies of IgG isotype that recognize purified GD2 by enzyme-linked immunosorbent assay (ELISA) and GD2-positive human melanoma cells (M21/P6) by fluorescence-activated cell sorter (FACS) analysis. The specificity of the antisera for GD2 was further confirmed by dot-blot analysis. These antisera also specifically lyse GD2-positive M21/P6 target cells in an antibody-dependent cellular cytotoxicity assay. Taken together, these results suggest that the anti-Id 1A7 can induce GD2-specific IgG antibodies that can recognize cell surface-associated as well as soluble disialoganglioside GD2.

Preclinical evaluation in nonhuman primates of murine monoclonal anti-idiotype antibody that mimics the disialoganglioside GD2

The antiganglioside GD2 monoclonal antibody 14G2a (Ab1) served as an immunogen to generate the anti-idiotype (anti-Id) 1A7 (IgG1,kappa), which mimics GD2 both antigenically and biologically. Anti-Id 1A7 induced anti-GD2 antibodies in mice and rabbits. In this preclinical study, a pair of cynomolgus monkeys, immunized with 1A7 that had been mixed with QS-21 adjuvant, produced anti-anti-Id antibodies (Ab3), which reacted with the GD2-positive melanoma cell line M21/P6 cells but not with GD2-negative LS174-T cells. The Ab3 shared Ids with mAb 14G2a (Ab1), as demonstrated by their ability to inhibit binding of 1A7 to this Ab1. The Ab3 bound specifically to purified GD2 antigen and competed with the Ab1 14G2a in binding to a GD2-positive melanoma cell line or to purified GD2, suggesting that Ab1 and Ab3 may bind to the same epitope and may behave as an Ab1-like antibody (Ab1'). The isotype of the GD2-specific antibodies was mostly IgG in nature. The specificity of the antibodies for GD2 was further confirmed by dot blot analysis. These antisera also specifically lysed GD2-positive target cells in an antibody-dependent cellular cytotoxicity assay. The induction of anti-GD2 responses in monkeys did not cause any apparent side effects, despite the fact that GD2 antigen is expressed by many normal tissues of these animals. Taken together, these results suggest that anti-Id 1A7 can induce GD2-specific antibodies in nonhuman primates and can thus serve as a potential network antigen for triggering active anti-GD2 antibodies in patients with GD2-positive neuroectodermal tumors.

IDEC-C2B8 (Rituximab) anti-CD20 monoclonal antibody therapy in patients with relapsed low-grade non-Hodgkin's lymphoma

IDEC-C2B8 is a chimeric monoclonal antibody (MoAb) directed against the B-cell-specific antigen CD20 expressed on non-Hodgkin's lymphomas (NHL). The MoAb mediates complement and antibody-dependent cell-mediated cytotoxicity and has direct antiproliferative effects against malignant B-cell lines in vitro. Phase I trials of single doses up to 500 mg/m2 and 4 weekly doses of 375 mg/m2 showed clinical responses with no dose-limiting toxicity. We conducted a phase II, multicenter study evaluating four weekly infusions of 375 mg/m2 IDEC-C2B8 in patients with relapsed low-grade or follicular NHL (Working Formulation groups A-D). Patients were monitored for adverse events, antibody pharmacokinetics, and clinical response. Thirty-seven patients with a median age of 58 years (range, 29 to 81 years) were treated. All patients had relapsed after chemotherapy (median of 2 prior regimens) and 54% had failed aggressive chemotherapy. Infusional side effects (grade 1-2) consisting of mild fever, chills, respiratory symptoms, and occasionally hypotension were observed mostly with the initial antibody infusion and were rare with subsequent doses. Peripheral blood B-cell depletion occurred rapidly, with recovery beginning 6 months posttreatment. There were no significant changes in mean IgG levels and infections were not increased over what would be expected in this population. Clinical remissions were observed in 17 patients (3 complete remissions and 14 partial remissions), yielding an intent to treat response rate of 46%. The onset of these tumor responses was as soon as 1 month posttreatment and reached a maximum by 4 months posttreatment. In the 17 responders, the median time to progression was 10.2 months (5 patients exceeding 20 months). Likelihood of tumor response was associated with a follicular histology, with the ability to sustain a high serum level of antibody after the first infusion, and with a longer duration of remission to prior chemotherapy. One patient developed a detectable but not quantifiable immune response to the antibody that had no clinical significance. IDEC-C2B8 in a dose of 375 mg/m2 weekly for 4 weeks has antitumor activity in patients with relapsed low-grade or follicular NHL. Results with this brief, outpatient treatment compare favorably with results with standard chemotherapy, and IDEC-C2B8 has a better safety profile. Further studies evaluating IDEC-C2B8 in other types of lymphoma either alone or combined with chemotherapy are warranted.

Clinical and immune responses in advanced colorectal cancer patients treated with anti-idiotype monoclonal antibody vaccine that mimics the carcinoembryonic antigen

Carcinoembryonic antigen (CEA) is expressed in a wide variety of adenocarcinomas, and it is well recognized that cancer patients are immunologically "tolerant" to CEA. The purpose of this study was to determine whether we could break immune tolerance to CEA by vaccinating patients with a monoclonal anti-idiotype antibody that is the internal image of CEA and to determine what impact this might have on patient survival. Twenty-four patients with advanced CEA-positive colorectal cancer who failed standard therapies except for two were entered into this Phase Ib trial. One patient was considered not assessable, because on the day of entering into the study, she was diagnosed with acute myelogenous leukemia. Patients were treated with 1, 2, or 4 mg of aluminum hydroxide-precipitated 3H1 anti-idiotype antibody every other week for four injections and then monthly until tumor progression was observed. Immunological monitoring included humoral and cellular idiotypic and CEA responses, and all patients were evaluated for toxicity, response, and survival. Hyperimmune sera from 17 of 23 patients demonstrated an anti-anti-idiotypic Ab3 response, and 13 of these responses were demonstrated to be true anti-CEA responses (Ab1'). The antibody response was polyclonal, and 11 mediated antibody-dependent cellular cytotoxicity. Ten patients had idiotypic T-cell responses, and five had specific T-cell responses to CEA. None of the patients had objective clinical responses, but overall median survival for the 23 evaluable patients was 11.3 months, with 44% 1-year survival (95% confidence interval, 23-64%). Toxicity was limited to local swelling and minimal pain. Anti-idiotype monoclonal antibody 3H1 that mimics CEA was able to break immune tolerance in the majority of treated patients. Overall survival of 11.3 months was comparable to other phase II data with advanced colorectal cancer patients treated with a variety of chemotherapy agents, including irinotecan, with considerably less toxicity. Although it is not clear that the vaccine itself had an impact on survival, this should be determined in a Phase III randomized trial.

Induction of antitumor immunity by an anti-idiotype antibody mimicking carcinoembryonic antigen

Carcinoembryonic antigen (CEA) is a tumor-associated antigen expressed on most gastrointestinal adenocarcinomas and is a putative target for cancer immunotherapy. We developed a murine monoclonal anti-idiotype (anti-Id) antibody, 3H1, which mimics a specific epitope of CEA, for cancer immunotherapy. In this study, the efficacy of 3H1 as a tumor vaccine was evaluated in a murine tumor model. In this model, the murine colorectal cancer cell line MC-38 was transduced with the human CEA gene and injected into syngeneic C57BL/6 (H-2b) mice. Immunization of naive mice with 3H1 conjugated with keyhole limpet hemocyanin Freund's adjuvant induced humoral and cellular anti-3H1 as well as anti-CEA immunity. Mice immunized with 3H1 were protected against a challenge with lethal doses of MC-38-cea, whereas no protection was observed when 3H1 vaccinated mice were challenged with CEA negative MC-38 cells or when mice were vaccinated with an unrelated anti-Id antibody and challenged with MC-38-cea cells (P < 0.003). These data demonstrate that the 3H1 vaccine can induce protective CEA-specific antitumor immunity.

Allogeneic bone marrow transplantation with T cell-depleted partially matched related donors for advanced acute lymphoblastic leukemia in children and adults: a comparative matched cohort study

Allogeneic BMT provides the best treatment currently available for long-term disease-free survival in patients with recurrent ALL. Historically, partially matched related donors provided the opportunity for treatment to a greater number of patients than matched related donors at the expense of decreased overall survival. In this study we compare the results in recurrent ALL patients transplanted with either HLA identical sibling bone marrow or partially matched related bone marrow. Thirty-two patients with relapsed ALL received partially matched bone marrows from a relative with one to three HLA, A, B and Dr antigen mismatches. Bone marrow was partially T cell-depleted with murine T10B9.1A-31 moAb. Sixteen patients with relapsed ALL received HLA-matched sibling bone marrows. All partially matched patients received additional GVHD prophylaxis with methylprednisolone in addition to anti-CD5 immunotoxin and/or CYA. All matched patients in addition to methylprednisolone received MTX and/or CYA. We observed no difference in disease-free survival between patients transplanted with partially matched bone marrow (median follow-up 1252 days, range 778-2035 days) vs those transplanted with HLA-matched bone marrow (median follow-up 1472 days, range 1165-2800 days; P = 0.48). Median survival for all patients is 38% (95% CI 24-52%) at 6 years. Patients transplanted in remission had a significant increase in disease-free survival when compared to those in relapse (P = 0.007). Our data suggest that partially matched BMTs from related donors are a comparable alternative to fully matched transplants in patients with ALL.

Immune responses in patients with T-cell lymphoma treated with an anti-idiotype antibody mimicking a highly restricted T-cell antigen

We generated an IgG1 murine monoclonal anti-idiotype antibody (Ab2) to a highly restricted T-cell antigen designated glycoprotein (gp) 37 that is found on T-cell malignancies but not on normal cells. gp37 is identified by the murine monoclonal antibody SN2 (Ab1) against which the Ab2 was raised. Each of four patients with T-cell lymphoma predominantly confined to the skin received a minimum of four intracutaneous injections of aluminum hydroxide precipitated anti-idiotype murine monoclonal antibody (1 mg/injection) given every 2 weeks. For responding patients, injections were continued on a monthly basis. All tumors were measured along orthogonal major and minor axes, using a ruler and/or calipers, by the same observer. Tumor sizes were documented photographically. Three of the four patients developed specific idiotypic humoral immune responses, and two of the four patients also demonstrated idiotypic cell-mediated responses. Humoral responses included binding of the patients' sera to the anti-idiotype antibody as well as specific inhibition of binding of the SN2 antibody (Ab1) to the anti-idiotype antibody (Ab2). Anti-anti-idiotypic (Ab3) antibody from one patient's serum bound specifically to the gp37-positive cell line MOLT-4 and also to semipurified gp37 antigen. Cell-mediated responses were demonstrated by specific proliferative response to the aluminum hydroxide precipitated anti-idiotype antibody by patients' peripheral blood mononuclear cells. While three of the four patients had extensive disease and did not have clinical responses, one of the patients who had nine discrete skin tumors and peripheral blood involvement without other detectable disease had virtually complete disappearance of the tumors lasting over 11 months. Our results demonstrate that this particular anti-idiotype antibody can induce humoral and cellular immune responses, and at least in one patient led to a meaningful therapeutic response. Future trials should focus on immunocompetent patients with minimal disease.

Preclinical evaluation in nonhuman primates of an anti-idiotypic antibody that mimicks the carcinoembryonic antigen

We have developed and characterized a murine monoclonal antiidiotype (Id) antibody (Ab2), designated 3H1 (IgG1-k) that mimics human carcinoembryonic antigen (CEA). 3H1 was raised against an anti-CEA monoclonal antibody (mAb) 8019 (Ab1) that recognizes a distinct and specific epitope of the 180,000 MW CEA. 3H1 induced specific anti-CEA immune responses in mice and rabbits. In this preclinical study, cynomolgus monkeys (Macaca fascicularis) were immunized with aluminum hydroxide-precipitated 3H1 and tested for the induction of anti-CEA antibodies. Monkeys were injected with 2 mg of 3H1, intracutaneously, four times biweekly. All monkeys developed specific anti-anti-Id (Ab3) responses that were capable of inhibiting binding of the immunizing 3H1 (Ab2) to 8019 (Ab1) and vice versa. Furthermore, immune sera from monkeys contained Ab3 (Abl') antibody that bound to CEA-positive colon carcinoma cell lines but not to CEA-negative MOLT-4 or melanoma cell lines. Also, the Ab3 reacted with purified CEA and competed with Ab1 (8019) for binding to CEA positive LS174-T cells, suggesting that Ab1 and Ab3 may bind to the same epitope. In addition, affinity-purified Ab3 from monkey sera immunoprecipitated the same 180,000 MW CEA as Ab1 8019 and showed an identical pattern as the Ab1 on colon carcinoma specimens by immunoperoxidase staining. The induction of anti-tumor antibodies in monkeys did not cause any apparent side effects. These data suggest that internal image anti-Id can induce tumor-specific humoral immune responses in nonhuman primates and can serve as potential network antigen for triggering active anti-CEA antibodies in colorectal cancer patients.

Immune response to the carcinoembryonic antigen in patients treated with an anti-idiotype antibody vaccine

We have generated an IgG1 murine monoclonal anti-idiotype antibody (Ab2) designated 3H1, which mimics a specific epitope on the carcinoembryonic antigen (CEA). Patients with CEA positive tumors are immunologically "tolerant" to CEA. We used 3H1 as a surrogate for CEA for vaccine therapy of 12 patients with advanced colorectal cancer. Each of the patients received a minimum of four intracutaneous injections of aluminum hydroxide precipitated 3H1 at either 1, 2, or 4 mg dosage per injection. 9 of 12 patients demonstrated anti-anti-idiotypic (Ab3) response to 3H1. All nine patients generated specific anti-CEA antibody demonstrated by reactivity with radiolabeled purified CEA; some cases were confirmed by immunoprecipitation of purified CEA. We also demonstrated Ab3 stained both autologous and allogeneic colonic tumors. 7 of 12 patients demonstrated idiotype specific T cell proliferative responses and four also showed T cell proliferation to CEA. Toxicity was limited to local reaction with mild fever and chills. All 12 patients eventually progressed after finishing 4-13 dosages. This is the first report demonstrating that a vaccine therapy is capable of breaking "immune tolerance" to CEA in patients with CEA positive tumors. Future studies will focus on treating patients with minimal residual disease.

Induction of human breast cancer-specific antibody responses in cynomolgus monkeys by a murine monoclonal anti-idiotype antibody

We have generated and characterized a murine monoclonal anti-idiotype (Id) antibody, designated 11D10, which biologically and antigenically mimics a distinct and specific epitope of the high molecular weight human milk fat globule primarily expressed by human breast and some other tumor cells at high density. This epitope is identified by mAb BrE1, which was used as the immunizing antibody or Ab1 to generate the anti-Id (Ab2) 11D10. 11D10 induced antitumor immune responses across species barriers, i.e., in mice and rabbits. In preclinical studies, cynomolgus monkeys were immunized with 2 mg of either 11D10 or the isotype- and allotype-matched control Ab2 3H1 after precipitation with aluminum hydroxide. All monkeys developed high titers of antibodies against the immunizing mouse immunoglobulin. Immunization with 11D10 induced anti-anti-idiotype antibodies (Ab3) which reacted with breast cancer cell lines but not with control T-cell and melanoma cell lines. The Ab3 shared idiotypes with BrE1 (Ab1), as demonstrated by their ability to inhibit 11D10 binding to BrE1. The Ab3 obtained with 11D10 bound specifically to human milk fat globule antigen and competed with BrE1 for binding to breast cancer cell lines, suggesting that Ab1 and Ab3 may bind to the same epitope. In addition, Id-specific cellular immune responses were demonstrated in monkeys immunized with 11D10 by T-cell proliferation assays. These results indicate that aluminum hydroxide-precipitated anti-Id 11D10 can induce breast cancer-specific antibodies in nonhuman primates and can serve as a potential network antigen for breast cancer patients.

Chronic lymphoid leukemias: recent advances in biology and therapy

There exists a wide variety of lymphoid leukemias derived from B and T lymphocytes. These diseases have distinct immunologic and biologic features as well as varied responses to therapeutics. The most common lymphoid leukemia is chronic lymphocytic leukemia (CLL) which is a clonal proliferation of a subset of B cells expressing the CD5 antigen. Prolymphocytic leukemia is usually derived from B cells and shares some features with CLL but is clearly a distinct entity. Hairy-cell leukemia is a B cell malignancy that is uniquely responsive to a variety of biologic and chemotherapeutic agents. Waldenström's macroglobulinemia is a B cell malignancy that secretes immunoglobulin M (IgM) and may present with the hyperviscosity syndrome. Other B cell malignancies that less commonly present as leukemias include non-Hodgkin's lymphomas such as follicular lymphoma or mantle zone lymphoma. Multiple myeloma may rarely present or evolve into a plasma cell leukemia, typically in far advanced disease. T cell malignancies that may present as chronic lymphoid leukemias, and in the past have often been referred to as T cell chronic lymphocytic leukemia, are large granular lymphocytic leukemia, adult T cell leukemia/lymphoma, Sézary cell leukemia and rare cases of non-Hodgkin's lymphoma that are T cell derived and may present or evolve into a leukemic phase. There is also a rare T cell counterpart of prolymphocytic leukemia. Distinguishing these diseases is critical for optimal care of these patients.