Comparative assessment of clinically utilized CD20-directed antibodies in chronic lymphocytic leukemia cells reveals divergent NK cell, monocyte, and macrophage properties.

CD20 is a widely validated, B cell-specific target for therapy in B cell malignancies. Rituximab is an anti-CD20 Ab that prolongs survival of chronic lymphocytic leukemia (CLL) patients when combined with chemotherapy. Ofatumumab and GA101 (obinutuzumab) are CD20-directed Abs currently being developed as alternative agents to rituximab in CLL based upon different properties of enhanced direct cell death, NK cell-mediated Ab-dependent cellular cytotoxicity, or complement-dependent cytotoxicity. Despite widespread study, ofatumumab and GA101 have not been compared with each other, nor studied for their interactions with monocytes and macrophages which are critical for the efficacy of anti-CD20 Abs in murine models. In CLL cells, we show that direct cell death and complement-dependent cytotoxicity are greatest with GA101 and ofatumumab, respectively. GA101 promotes enhanced NK cell activation and Ab-dependent cellular cytotoxicity at high Ab concentrations. Ofatumumab elicits superior Ab-dependent cellular phagocytosis with monocyte-derived macrophages. GA101 demonstrated reduced activation of monocytes with diminished pERK, TNF-α release, and FcγRIIa recruitment to lipid rafts. These data demonstrate that GA101 and ofatumumab are both superior to rituximab against CLL cells via different mechanisms of potential tumor elimination. These findings bear relevance to potential combination strategies with each of these anti-CD20 Abs in the treatment of CLL.

Multicenter study of subcutaneous alemtuzumab administered at reduced dose in patients with fludarabine-relapsed/refractory chronic lymphocytic leukemia: final analysis.

Optimal management of patients with relapsed/refractory chronic lymphocytic leukemia (CLL) has been the motive behind a large number of studies in recent years, and previous response, its duration, and development of clonal evolution appear to be the best indicators for the choice of a new regimen. Although alemtuzumab in relapsed/refractory CLL may be beneficial, the optimal dosage and risk of infection related to its use remain thus far deeply controversial issues. In this pilot phase II study we investigated the feasibility of, toxicity of, and response to alemtuzumab at a reduced dose (30 mg s.c. for 2 weeks and then once a week at extended intervals: every 2, 4, 6 weeks up to 1 year). The overall response rate was 95%, with 51% complete response. The complete response range was 55% in fludarabine-relapsed patients and 28% in patients with fludarabine-refractory disease, without significant difference between the two groups. The regimen was well tolerated with mild toxicity and few cytomegalovirus (CMV) infections. With a median follow-up of 27 months, the overall survival (46% at 3 years) appears to be similar to that with other regimens although with fewer adverse events. In conclusion, treatment with alemtuzumab at a reduced dose seems to be safe and increases the event-free survival of patients with relapsed/refractory CLL, compared with the standard dose. A randomized study comparing both regimens including a larger number of patients is warranted.

A caveat for T cell transfer studies: generation of cytotoxic anti-Thy1.2 antibodies in Thy1.1 congenic mice given Thy1.2+ tumors or T cells.

Thy1.1 congenic B6.PL mice were used to simultaneously monitor Thy1.2+ E.G7-OVA tumors transplanted in the a.c. of the eye and i.v.-transferred tumor-specific Thy1.2+ CTLs to determine mechanisms that inhibit the tumoricidal activity of CTL responses in mice with established ocular tumors. Transferred CTLs were systemically deleted in mice with established ocular tumors. However, this deletion was not a unique mechanism of immune evasion by ocular tumors. Rather, development of Thy1.2+ tumors in the eye or skin of B6.PL mice generated cytotoxic anti-Thy1.2 antibodies that eliminated a subsequent Thy1.2+ T cell transfer. Anti-Thy1.2 immune responses in B6.PL mice were influenced by the route of antigen administration, as the serum concentration of cytotoxic anti-Thy1.2 antibodies was 92-fold greater in mice with eye tumors in comparison with mice with skin tumors. In addition, anti-Thy1.2 immune responses were detected in B6.PL mice given naïve Thy1.2+ T cells i.p. but not i.v. Anti-Thy1.2 responses were augmented in B6.PL mice with ocular Thy1.2+ EL-4 tumors that did not express OVA, suggesting immunodominance of OVA antigen over Thy1.2. Thy1.1+ T cells given i.p. was not immunogenic in Thy1.2 congenic mice. These data reaffirm that the introduction of antigens in the a.c. induces robust antibody responses. Experimentation using allotypic differences in Thy1 between donor cells and recipient mice must consider cytotoxic anti-Thy1 antibody generation in the interpretation of results.

New antitumoral agents I in vitro anticancer activity and in vivo acute toxicity of synthetic 15 bis(4-hydroxy-3-methoxyphenyl)14pentadien 3 one and derivatives

This paper describes a new method for the preparation of 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadien-3-one 1 and its derivatives 2–5. This set of synthetic compounds exhibited high antitumoral activities regarding in vitro screening against several human tumor cell lines as lung carcinoma NCI-460, melanoma UACC-62, breast MCF-7, colon HT-29, renal 786-O, ovarian OVCAR-03 and ovarian expressing the resistance phenotype for adriamycin NCI-ADR/RES, prostate PC-3, and leukemia K-562. Compounds were also tested against murine tumor cell line B16F10 melanoma and lymphocytic leukemia L1210 as well as to their effect toward normal macrophages. Specific activity against colon cancer cells HT-29 was observed for all tested compounds and suggests further studies with models of colon cancer. Compounds 1, 2, and 4 showed significant cytotoxic activity with IC50 values ⩽2.3 ìM for all human cancer cell lines. Intraperitoneal acute administration of compound 1 and 2 showed very low toxicity rate.

A phase II study of Campath-1H in children with relapsed or refractory acute lymphoblastic leukemia: a Children's Oncology Group report.

BACKGROUND: Despite the increasing cure rates for children with acute lymphoblastic leukemia (ALL), patients who relapse continue to have poor prognosis. The Children's Oncology Group (COG) conducted a limited institution Phase II trial of Campath-1H, a monoclonal antibody that targets CD52 on leukemic cells, in children with relapsed or refractory ALL. METHODS: From October 2005 to December 2006, 13 eligible patients were enrolled on the COG phase II study of Campath-1H (ADVL0222). Campath-1H was initially administered as an intravenous infusion over 2 hr, five times per week for 1 week, then three times per week for three additional weeks. Patients with stable disease or better on day 29 could continue on to combination therapy with Campath-1H, methotrexate, and 6-mercaptopurine for two additional cycles. RESULTS: One of 13 patients enrolled had a complete response to Campath-1H and 4 had stable disease. Dose limiting toxicity occurred in two out of nine fully evaluable patients (Grade IV pain and Grade III allergic reaction/hypersensitivity). No patients received combination therapy. Serum Campath-1H concentrations appeared to be somewhat lower in children with ALL compared with adult patients with chronic lymphocytic leukemia. CONCLUSION: Although a single complete response was observed, activity of single agent Campath-1H appears limited. Our study does not support future single agent evaluation of Campath-1H in children with relapsed ALL.

Alemtuzumab as treatment of steroid-refractory acute graft-versus-host disease: results of a phase II study.

We conducted a phase II trial to investigate the safety and efficacy of alemtuzumab in treating steroid-refractory acute graft-versus-host disease (aGVHD) grade II or higher after stem cell transplantation. Ten adult patients (6 with aGVHD grade III and 4 with aGVHD grade IV) were included in the study. Nine patients had gastrointestinal tract involvement, 7 had skin involvement, and 5 had liver involvement. Five patients responded to treatment, 2 with complete response and 3 with partial response. Eight infectious events (4 of grade 3-4) and 7 cytomegalovirus (CMV) reactivations were observed. Six patients had grade 3-4 cytopenia. All 10 patients died (7 resulting from aGVHD progression, 2 from severe infection, and 1 from to leukemia relapse), at a median of 40 days (range, 4 to 88 days) after alemtuzumab treatment. Overall, our findings suggest that steroid-refractory aGVHD may be improved by treatment with alemtuzumab, but that this treatment does not overcome the dismal prognosis of patients with severe aGVHD, demonstrating the need for alternative therapies to treat this complication.

Alemtuzumab (CAMPATH-1H) for the treatment of acute rejection in kidney transplant recipients: long-term follow-up.

BACKGROUND: Alemtuzumab (MabCampath, Campath-1H) is a lymphocyte-depleting monoclonal antibody increasingly used in renal transplantation. This article reports the long-term follow-up data from the first series of patients treated with alemtuzumab for biopsy-proven acute rejection (BPAR). METHODS: Fifteen patients were identified who had received alemtuzumab for BPAR between November 1991 and June 1994. Patient and allograft survival were compared with a control group consisting of 25 patients with BPAR from the same era treated with intravenous methyl prednisolone, and with a contemporaneous UK renal transplant cohort. RESULTS: All rejection episodes responded to treatment with alemtuzumab but there was an excess of early infection-associated death in this group. Long-term transplant survival was similar in both groups as was allograft function (mean creatinine concentration at 10 years was 143 micromol/L in alemtuzumab cohort and 183 micromol/L in control cohort, P=0.06). There was no excess incidence of malignancy or cytomegalovirus infection in this prolonged follow-up period.

Low-dose intermittent alemtuzumab in the treatment of Sézary syndrome: clinical and immunologic findings in 14 patients.

BACKGROUND AND OBJECTIVES: Alemtuzumab may be effective in Sézary syndrome (SS), an aggressive cutaneous T-cell lymphoma, but is associated with severe hematologic toxicity and infections. This study investigated whether low-dose subcutaneous alemtuzumab can induce hematologic, immunologic, and clinical responses similar to those obtained with the standard regimen, but with less toxicity. DESIGN AND METHODS: Fourteen SS patients were enrolled: 11 had relapsed/refractory disease and three had untreated SS with high counts of circulating Sézary cells (SC). Four received 3 mg alemtuzumab on day 1, 10 mg on day 3, then 15 mg on alternating days; circulating SC were evaluated after the fourth 15 mg dose and treatment was interrupted in the presence of counts <1,000/mm (3). A reduced dosage (3 mg on day 1, then 10 mg on alternating days) was administered to the remaining patients, with SC counted before every injection, until a reduction to values of <1,000/mm (3). RESULTS: The median SC count decreased by 95.5%. Overall, 12/14 patients (85.7%) achieved a clinical response, with three complete responses (21.4%). After a median follow-up of 16 months, the median time-to-treatment failure is 12 months. Infectious complications occurred in 28.6% of patients, all included in the group treated with 15 mg. No patient in the group treated with 10 mg developed hematologic toxicity or infections. An early recovery of circulating NK, B and CD3+CD8+ cells occurred after the first cycle. INTERPRETATION AND CONCLUSIONS: Subcutaneous alemtuzumab at very low doses (10 mg maximum per administration), given for a short period based on SC levels, has a good toxicity profile, high response rate and causes durable remissions in SS patients with high tumor burden in the peripheral blood.

Targeting melanoma cells with human high molecular weight-melanoma associated antigen-specific antibodies elicited by a peptide mimotope: functional effects.

Human high molecular weight-melanoma associated Ag (HMW-MAA) mimics have been shown to elicit HMW-MAA-specific humoral immune responses that appear to be clinically beneficial. This finding has stimulated interest in characterizing the mechanism(s) underlying the ability of the elicited Abs to exert an anti-tumor effect. To address this question, in the present study, we have generated HMW-MAA-specific Abs by sequentially immunizing rabbits with the peptide P763.74, which mimics the HMW-MAA determinant recognized by mAb 763.74, and with HMW-MAA(+) melanoma cells. HMW-MAA-specific Abs isolated from immunized rabbits mediated cell-dependent cytotoxicity but did not mediate complement-dependent cytotoxicity of HMW-MAA(+) melanoma cells. These Abs also effectively inhibited spreading, migration and Matrigel invasion of HMW-MAA(+) melanoma cells. Besides contributing to our understanding of the role of HMW-MAA in the biology of melanoma cells, these results suggest that both immunological and nonimmunological mechanisms underlie the beneficial clinical effects associated with the induction of HMW-MAA-specific Abs in melanoma patients immunized with a HMW-MAA mimic.

Subcutaneous alemtuzumab vs ATG in adjusted conditioning for allogeneic transplantation: influence of Campath dose on lymphoid recovery, mixed chimerism and survival.

Sixty-nine consecutive patients (median age 54 years) were prospectively enrolled in a single-institution protocol for allogeneic transplantation with adjusted non-myeloablative fludarabine-melfalan-based conditioning including cyclosporin A and MMF, and one of three modes of serotherapy. Thirty-one donors (45%) were unrelated. The first cohort of 29 had ATG (Thymoglobulin 2 mg/kg x 3 days), the subsequent 26 had Campath 30 mg x 3 days subcutaneously, and the final cohort of 14 had 30 mg Campath once. The groups were similar as regards age, diagnosis and risk factors. Campath-patients had no acute toxicity, fewer days with fever and antibiotics, and required fewer transfusions than ATG-treated patients. 3-d-Campath patients showed lower lymphocyte counts from day +4, and CD4+, CD8+, CD19+ and NK cells recovered slower than in ATG-treated patients. More Campath patients developed mixed chimerism that required DLI. 3-d-Campath induced more serious and opportunistic infections than ATG, which resulted in a greater non-relapse mortality and an impaired overall survival despite a low tumor-related mortality. The change of the Campath dosing schedule to one dose abrogated the deleterious effect of 3-d-Campath on immune recovery, severe infections and survival. Subcutaneous Campath is simple and provides strong immune suppression with no early toxicity, but dose limitation to 30 mg once is recommended.

Adenovirus infection rates in pediatric recipients of alternate donor allogeneic bone marrow transplants receiving either antithymocyte globulin (ATG) or alemtuzumab (Campath).

Infectious complications due to adenovirus are of increasing concern after allogeneic stem cell transplantation. Over the past 4 years, we have modified our conditioning regimens to use alemtuzumab in preference to anti-thymocyte globulin (ATG) for pediatric patients receiving stem cell transplants from alternate donors. Recent reports in adult studies implicate alemtuzumab as a risk factor for adenovirus infection. We therefore evaluated the incidence of adenovirus infection in pediatric patients receiving either ATG or alemtuzumab in their conditioning regimens. Of the 111 patients evaluated, a total of 54 patients received ATG and 57 patients received alemtuzumab. In total, 35/111 (32%) patients were infected by adenovirus, and 9/111 (8%) had adenovirus disease (AD). Adenovirus infection was greater in the alemtuzumab group than the ATG group (23/57 vs 12/54) (P=0.039) and disseminated AD was more frequent in the alemtuzumab group vs the ATG group (8/57 and 1/54 respectively) (P=0.032). The presence of Grade 3-4 graft-versus-host disease was a risk factor for adenovirus infection. Our findings highlight the fact that adenovirus infection is a frequent complication after stem cell transplantation from alternate donors in the pediatric population and that alemtuzumab increases the risk of infection compared to ATG. This work will help in identifying at-risk populations for our upcoming immunotherapy trial using adoptively transferred donor-derived adenovirus-specific cytotoxic T lymphocytes.

Antibodies against tumor cell glycolipids and proteins, but not mucins, mediate complement-dependent cytotoxicity.

One of several effector mechanisms thought to contribute to Ab efficacy against cancer is complement-dependent cytotoxicity (CDC). Serological analysis of a series of clinical trials conducted over a 10-year period suggested that six vaccines containing different glycolipids induced Abs mediating CDC whereas four vaccines containing carbohydrate or peptide epitopes carried almost exclusively by mucin molecules induced Abs that did not mediate CDC. To explore this further, we have now compared cell surface reactivity using flow cytometry assays (FACS), complement-fixing ability, and CDC activity of a panel of mAbs and immune sera from these trials on the same two tumor cell lines. Abs against glycolipids GM2, globo H and Lewis Y, protein KSA (epithelial cell adhesion molecule, also known as EpCAM) and mucin Ags Tn, sialylated Tn, Thomsen Friedenreich (TF), and MUC1 all reacted comparably by FACS with tumor cells expressing these Ags. Compared with the strong complement binding and CDC with Abs against glycolipids and KSA, complement binding was diminished with Abs against mucin Ags and no CDC was detected. A major difference between these two groups of Ags is proximity to the cell membrane. Glycolipids and globular glycoproteins extend less than 100 A from the cell membrane while mucins extend up to 5000 A. Although complement activation at sites remote from the cell membrane has long been known as a mechanism for resistance from complement lysis in bacteria, it is identified here for the first time as a factor which may contribute to resistance from CDC against cancer cells.

Maintenance therapy with a monthly injection of alemtuzumab prolongs response duration in patients with refractory B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma (B-CLL/SLL).

Alemtuzumab, the monoclonal anti-CD52 antibody, has clinical activity in B-cell and T-cell malignancies at the dose of 30 mg three times weekly for 9-12 weeks. This standard regimen induced responses usually shorter than 6 months. To prolong time to progression, we initialized a phase II study with an identical initial scheme until partial response, followed by a maintenance therapy lasting at least 4 months. Eleven heavily pretreated patients (8 with B-chronic lymhocytic leukemia (B-CLL) and 3 with small lymphoctyic lymphoma (SLL)) have been treated with this maintenance regimen (MR patients) and were retrospectively compared to 5 patients (3 B-CLL and 2 SLL) treated with the standard regimen (SR patients). Patients characteristics before treatment were identical in both groups. Objective response was reached by 9 (82%) MR patients and 3 (60%) SR patients (p NS). After the treatment, 8 (73%) MR patients and all SR patients progressed with a median time at 12.2 months and 3 months respectively. Survival time from alemtuzumab was significatively different (P < 0.005). None of the patients died in the MR group with a median follow-up at 16 months. In the SR group, the median survival from alemtuzumab was 5.9 months. We did not observe any differences in terms of hematological toxicites and infections between the two groups. In conclusion, maintenance alemtuzumab therapy seems to increase the time to progression and the survival, without adding hematological toxicities and infectious complications. More patients are needed to confirm this observation.

Cardiac toxicity of alemtuzumab in patients with mycosis fungoides/Sézary syndrome.

Alemtuzumab is a monoclonal antibody to CD52 that has activity in T-cell leukemia and lymphoma. This study aims to describe the complications and outcomes of a subset of patients with mycosis fungoides/Sézary syndrome who were treated with alemtuzumab. Four of 8 patients, with no prior history of cardiac problems, developed significant cardiac toxicity (congestive heart failure or arrhythmia) that mostly improved after alemtuzumab discontinuation. The role of this agent in potentially inducing important cardiac side effects is suggested and argues for further investigation.

Cellular association and cytotoxicity of anti-CD74-targeted lipid drug-carriers in B lymphoma cells.

The ability to selectively target anti-cancer drugs via specific ligands against antigens expressed on malignant cells could greatly improve the therapeutic indices of the drugs. In this paper an anti-CD74 antibody (Ab), LL1, was covalently attached to the surface of sterically stabilized lipid drug-carriers (emulsions and liposomes) by use of a PEG-based heterobifunctional coupling agent. Target cells internalize LL1 very fast and that was found to be true for the LL1-lipid drug-carrier complexes as well. During a 24 h in vitro incubation with the target Raji B-lymphoma cells about 30% of the added complexes were associated with the cells. The corresponding value for drug-carrier without targeting ligand was near 0.6%. Displacement experiments showed that free LL1 competed well with LL1-complexes indicating preserved immunoreactivity. Non-target cells showed only unspecific association of LL1-complexes. A dioleoylated derivative of the anti-cancer drug 3',5'-O-dioleoyl-FUdR (FUdR) (FUdR-dO) loaded into LL1-lipid drug-carriers showed good cytotoxic activity. In vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity tests against neoplastic B-cells gave IC30 values of 0.45, 1.25, 5.30 and 7.30 microM for the prodrug FUdR-dO in LL1-emulsions, LL1-liposomes, emulsions and liposomes, respectively. The value for the parent drug FUdR was calculated to 4.35 microM. In the light of the extensive and specific delivery of LL1-lipid drug-carriers to B-cells and the selective cytotoxicity of the incorporated drug, we infer that the complexes may be useful in the selective elimination of circulating malignant B-cells in vivo.

Phase 2 study of alemtuzumab (anti-CD52 monoclonal antibody) in patients with advanced mycosis fungoides/Sezary syndrome.

This phase 2 study evaluated the safety and efficacy of alemtuzumab in 22 patients with advanced mycosis fungoides/Sézary syndrome (MF/SS). Most patients had stage III or IV disease, reduced performance status, and severe itching. The overall response (OR) rate was 55%, with 32% of patients in complete remission (CR) and 23% in partial remission (PR). Sézary cells were cleared from the blood in 6 of 7 (86%) patients, and CR in lymph nodes was observed in 6 of 11 (55%) patients. The effect was better on erythroderma (OR, 69%) than on plaque or skin tumors (OR, 40%) and in patients who had received 1 to 2 previous regimens (OR, 80%) than in those who had received 3 or more prior regimens (OR, 33%). Itching, self-assessed on a 0 to 10 visual analog scale, was reduced from a median of 8 before treatment to 2 at end of therapy. Median time to treatment failure was 12 months (range, 5-32+ months). Cytomegalovirus (CMV) reactivation (causing fever without pneumonitis and responding to ganciclovir) occurred in 4 (18%) patients. Six additional patients had suspect or manifest infection (fever of unknown origin, 3; generalized herpes simplex, 1; fatal aspergillosis, 1). One patient had fatal Mycobacterium pneumonia at 10+ months. All serious infectious adverse events (except CMV) occurred in patients who had received 3 or more prior regimens. Progression of squamous cell skin carcinoma was noted in 1 patient. Alemtuzumab shows promising clinical activity and an acceptable safety profile in patients with advanced MF/SS, particularly in patients with erythroderma and severe itching and those who were not heavily pretreated.

Phase II trial of subcutaneous anti-CD52 monoclonal antibody alemtuzumab (Campath-1H) as first-line treatment for patients with B-cell chronic lymphocytic leukemia (B-CLL).

This phase II study determined the efficacy and safety of alemtuzumab, a humanized anti-CD52 monoclonal antibody, delivered subcutaneously as first-line therapy, over a prolonged treatment period of 18 weeks in 41 patients with symptomatic B-cell chronic lymphocytic leukemia (B-CLL). Injections were administered subcutaneously 3 times per week, from week 2 to 3 onward. An overall response rate (OR) of 87% (95% CI, 76%-98%; complete remission [CR], 19%; partial remission [PR], 68%) was achieved in 38 evaluable patients (81% of intent-to-treat population). CLL cells were cleared from blood in 95% patients in a median time of 21 days. CR or nodular PR in the bone marrow was achieved in 66% of the patients and most patients achieved this after 18 weeks of treatment. An 87% OR (29% CR) was achieved in the lymph nodes. The median time to treatment failure has not yet been reached (18+ months; range, 8-44+ months). Transient injection site skin reactions were seen in 90% of patients. Rigor, rash, nausea, dyspnea, and hypotension were rare or absent. Transient grade IV neutropenia developed in 21% of the patients. Infections were rare, but 10% patients developed cytomegalovirus (CMV) reactivation. These patients rapidly responded to intravenous ganciclovir. One patient, allergic to cotrimoxazole prophylaxis, developed Pneumocystis carinii pneumonia. Alemtuzumab is highly effective as first-line treatment in patients with B-CLL. Prolonged treatment is important for maximal bone marrow response. Subcutaneous administration induced very few "first-dose" flulike symptoms and may reduce health care costs in comparison with the intravenous infusions.

Safety and efficacy of subcutaneous Campath-1H for treating residual disease in patients with chronic lymphocytic leukemia responding to fludarabine.

BACKGROUND AND OBJECTIVES: Recent observations suggested that targeted monoclonal antibodies might be best employed in lymphoid malignancies under conditions of minimal residual disease. This prompted us to investigate the role of Campath-1H as treatment for patients with chronic lymphocytic leukemia (CLL) in whom fludarabine (FAMP) had produced a marked disease debulking with persistence of bone marrow (BM) infiltration or a complete remission (CR) without the disappearance of the molecular aberration (IgH monoclonal expression). As intravenous Campath-1H is almost invariably associated with reactions, sometimes of WHO grade 3-4, we adopted the subcutaneous route of administration, which proved to induce rare and mild adverse reactions but had comparable efficacy. DESIGN AND METHODS. Nine patients (7 males, 2 females) with a median age of 55 years (range 41-61) who responded to FAMP (1 had a CR, 5 a nodular partial remission [PRN], and 3 a partial remission [PR]), according to NCI Working Group Criteria, received subcutaneous Campath-1H, three times a week for 6 weeks in escalating doses up to 10 mg. Monoclonal rearrangement of IgH was present in all patients before immunotherapy. Patients received acyclovir and cotrimoxazole as infection prophylaxis. Granulocyte colony-stimulating factor (G-CSF), at the dosage of 5-10 microg/kg/die, or intermediate-dose Ara-C (800 mg/m(2)/q 12h x 6 doses), was administered to obtain peripheral blood stem cell (PBSC) mobilization. RESULTS: All patients were evaluable for response. Five patients, 2 in PR and 3 in PRN after FAMP treatment, reached a CR. Three patients, one in PR, one in PRN and one in CR, converted to a molecular remission. In four out of seven patients PBSC harvesting was successful; more than 2.5 x 10(6) cells/kg were collected from all these patients. Collection was polyclonal for IgH gene rearrangement in three cases. One patient has been transplanted after cyclophosphamide and total body irradiation as conditioning regimen, without complications and with rapid hemopoietic engraftment. All patients were evaluable for toxicity. A WHO grade 1-2 skin reaction was observed in 5 patients at the site of injection. No infectious episodes were recorded. Two out of three patients presenting cytomegalovirus reactivation, without pneumonia, were successfully treated with oral gancyclovir. INTERPRETATION AND CONCLUSIONS: Subcutaneous Campath-1H administered to CLL patients with residual BM disease after FAMP proved to be safe and effective. Of nine patients, three obtained a molecular CR and five converted into a morphologic and immunophenotypic CR. In four of seven patients submitted to PBSC mobilization, this treatment also allowed a harvest uncontaminated by CD5/CD19 double-positive CLL cells, which was polyclonal for IgH gene rearrangement in three cases.