Pertuzumab, trastuzumab, and docetaxel for HER2-positive metastatic breast cancer (CLEOPATRA): end-of-study results from a double-blind, randomised, placebo-controlled, phase 3 study

BACKGROUND

CLEOPATRA was a phase 3 study comparing the efficacy and safety of pertuzumab, trastuzumab, and docetaxel with placebo, trastuzumab, and docetaxel in patients with HER2-positive metastatic breast cancer. In the primary analysis and subsequent reports, progression-free and overall survival were significantly improved in the pertuzumab group compared with the placebo group. Here, we report the end-of-study analysis of CLEOPATRA.

METHODS

This was a double-blind, randomised, placebo-controlled, phase 3 trial that was done at 204 centres in 25 countries. Eligible patients were 18 years or older, had HER2-positive, metastatic breast cancer, had not received previous chemotherapy or biological treatment for their metastatic disease, and had an Eastern Cooperative Oncology Group performance status of 0 or 1. All study drugs were given intravenously, every 3 weeks. Patients were assigned to receive either pertuzumab or placebo at a loading dose of 840 mg, and 420 mg thereafter; plus trastuzumab at 8 mg/kg loading dose and 6 mg/kg thereafter; and docetaxel at 75 mg/m², escalating to 100 mg/m² if tolerated. Pertuzumab or placebo and trastuzumab were given until disease progression; docetaxel was given for six cycles, or longer at the investigators' discretion. Randomisation (1:1) was done by use of an interactive voice-response system and was stratified by geographical region (Asia, Europe, North America, or South America) and previous treatment (previous adjuvant or neoadjuvant chemotherapy vs none). The primary endpoint was independent review facility-assessed progression-free survival, which has been reported previously. Since the confirmatory overall survival analysis had also occurred before this prespecified end-of-study analysis, analyses presented here are descriptive. Overall survival analyses were based on the intention-to-treat population with crossover patients analysed in the placebo group; analyses were not adjusted for crossover to the pertuzumab group and are likely to be conservative. Safety analyses were based on treatment received; crossover patients were counted in the placebo group up to the day before first pertuzumab dose. This trial is registered with ClinicalTrials.gov, number NCT00567190.

FINDINGS

Between Feb 12, 2008, and July 7, 2010, 1196 patients were assessed for eligibility, of whom 808 were enrolled and randomly assigned. 402 patients were assigned to receive docetaxel plus trastuzumab plus pertuzumab, and 406 patients were assigned to receive docetaxel plus trastuzumab plus placebo. Clinical cutoff for this analysis was Nov 23, 2018. Between July 2012 and clinical cutoff, 50 patients crossed from the placebo to the pertuzumab group. Median follow-up was 99·9 months in the pertuzumab group (IQR 92·9-106·4) and 98·7 months (90·9-105·7) in the placebo group. Median overall survival was 57·1 months (95% CI 50-72) in the pertuzumab group and 40·8 months (36-48) in the placebo group (hazard ratio 0·69, 95% CI 0·58-0·82); 8-year landmark overall survival rates were 37% (95% CI 31-42) in the pertuzumab group and 23% (19-28) in the placebo group. The most common grade 3-4 adverse event was neutropenia (200 [49%] of 408 patients in the pertuzumab group, 183 [46%] of 396 patients in the placebo group). Five (1%) of 408 patients in the pertuzumab group and six (2%) of 396 patients in the placebo group had treatment-related deaths. One new serious adverse event suggestive of congestive heart failure (pertuzumab group) and one new symptomatic left ventricular systolic dysfunction (post-crossover) occurred since the previous analysis.

INTERPRETATION

Our analysis shows that the previously observed improvements in overall survival with pertuzumab, trastuzumab, and docetaxel versus placebo, trastuzumab, and docetaxel were maintained after a median of more than 8 years of follow-up. The long-term safety and cardiac safety profiles of pertuzumab, trastuzumab, and docetaxel were maintained in the overall safety population and within crossover patients. HER2-targeted therapy has changed the natural history of HER2-positive metastatic breast cancer, with the dual blockade of pertuzumab and trastuzumab, with docetaxel, demonstrating an 8-year landmark overall survival rate of 37%.

FUNDING

F Hoffmann-La Roche and Genentech.

Pharmacokinetic and exposure-response analyses of pertuzumab in combination with trastuzumab and docetaxel during neoadjuvant treatment of HER2+ early breast cancer

Purpose

The NeoSphere trial evaluated pertuzumab in the neoadjuvant setting [early breast cancer (EBC)] with pathological complete response (pCR) as the primary efficacy end point. This analysis of pertuzumab aimed to (1) compare its pharmacokinetics (PK) in patients with EBC versus advanced cancers, (2) to further evaluate PK drug–drug interactions (DDIs) when given in combination with trastuzumab, and (3) to assess the relationship between exposure and efficacy to assess the clinical dosing regimen in the EBC patients.

Methods

Pertuzumab serum concentration data from 180 patients in NeoSphere were compared to historical observations and potential DDI was assessed, by applying simulation techniques using a population PK model. The impact of pertuzumab exposure on pCR rate was evaluated using a logit response model (n = 88).

Results

The observed PK matched the population PK model simulations, confirming that the PK in neoadjuvant EBC appear to be in agreement with the historical observations. No evidence of a DDI effect of trastuzumab or docetaxel on pertuzumab was observed supporting the doses when given in combination. In NeoSphere >90% of EBC patients achieved the non-clinical target serum concentration. There was no association between the pertuzumab serum concentration and pCR within the range observed in this study (20–100 μg/mL) supporting no dose adjustments needed for patients with lower exposure.

Conclusions

This analysis further supports the lack of DDI between the two therapeutic proteins and the appropriateness of the approved fixed non-body-weight-adjusted pertuzumab dose in the treatment of neoadjuvant EBC with pertuzumab in combination with trastuzumab and docetaxel.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-016-3218-0) contains supplementary material, which is available to authorized users.

Pertuzumab, trastuzumab, and docetaxel in HER2-positive metastatic breast cancer

BACKGROUND

In patients with metastatic breast cancer that is positive for human epidermal growth factor receptor 2 (HER2), progression-free survival was significantly improved after first-line therapy with pertuzumab, trastuzumab, and docetaxel, as compared with placebo, trastuzumab, and docetaxel. Overall survival was significantly improved with pertuzumab in an interim analysis without the median being reached. We report final prespecified overall survival results with a median follow-up of 50 months.

METHODS

We randomly assigned patients with metastatic breast cancer who had not received previous chemotherapy or anti-HER2 therapy for their metastatic disease to receive the pertuzumab combination or the placebo combination. The secondary end points of overall survival, investigator-assessed progression-free survival, independently assessed duration of response, and safety are reported. Sensitivity analyses were adjusted for patients who crossed over from placebo to pertuzumab after the interim analysis.

RESULTS

The median overall survival was 56.5 months (95% confidence interval [CI], 49.3 to not reached) in the group receiving the pertuzumab combination, as compared with 40.8 months (95% CI, 35.8 to 48.3) in the group receiving the placebo combination (hazard ratio favoring the pertuzumab group, 0.68; 95% CI, 0.56 to 0.84; P<0.001), a difference of 15.7 months. This analysis was not adjusted for crossover to the pertuzumab group and is therefore conservative. Results of sensitivity analyses after adjustment for crossover were consistent. Median progression-free survival as assessed by investigators improved by 6.3 months in the pertuzumab group (hazard ratio, 0.68; 95% CI, 0.58 to 0.80). Pertuzumab extended the median duration of response by 7.7 months, as independently assessed. Most adverse events occurred during the administration of docetaxel in the two groups, with long-term cardiac safety maintained.

CONCLUSIONS

In patients with HER2-positive metastatic breast cancer, the addition of pertuzumab to trastuzumab and docetaxel, as compared with the addition of placebo, significantly improved the median overall survival to 56.5 months and extended the results of previous analyses showing the efficacy of this drug combination. (Funded by F. Hoffmann-La Roche and Genentech; CLEOPATRA ClinicalTrials.gov number, NCT00567190.).

Pertuzumab, trastuzumab, and docetaxel for HER2-positive metastatic breast cancer (CLEOPATRA study): overall survival results from a randomised, double-blind, placebo-controlled, phase 3 study

BACKGROUND

CLEOPATRA is a phase 3 study to compare the efficacy and safety of pertuzumab, trastuzumab, and docetaxel with placebo, trastuzumab, and docetaxel in patients with HER2-positive first-line metastatic breast cancer. The results of the primary analysis showed significantly longer median progression-free survival in the pertuzumab group than in the placebo group. Interim analysis of overall survival favoured the pertuzumab group but was not significant. Here, we report results for overall survival after an additional year of follow-up.

METHODS

The study was a double-blind randomised trial undertaken at 204 centres in 25 countries. Patients with HER2-positive metastatic breast cancer who had not received previous chemotherapy or biological treatment for their metastatic disease were randomly assigned to receive either pertuzumab, trastuzumab, and docetaxel (n=402) or the same regimen with a matching placebo replacing pertuzumab (n=406). Randomisation was in a 1:1 ratio, stratified by geographical region and previous treatment status. The primary endpoint was progression-free survival (assessed independently), which has been reported previously; no follow-up data were gathered for the primary endpoint. Secondary endpoints included overall survival, progression-free survival (assessed by investigator), objective response rate, and safety. Median follow-up was 30 months in both groups. Efficacy endpoints were analysed in the intention-to-treat population and safety was analysed by treatment received. The study is completed but safety and survival data continue to be followed up. This trial is registered with ClinicalTrials.gov, number NCT00567190.

FINDINGS

In the intention-to-treat population, 267 patients died by data cutoff (May 14, 2012), 154 (38%) of 406 in the placebo group and 113 (28%) of 402 in the pertuzumab group. Median overall survival was 37.6 months (95% CI 34.3-NE [not estimable]) in the placebo group but had not been reached (95% CI 42.4-NE) in the pertuzumab group (hazard ratio 0.66, 95% CI 0.52-0.84; p=0.0008). Investigator-assessed median progression-free survival was 12.4 months (95% CI 10.4-13.5) in the placebo group and 18.7 months (16.6-21.6) in the pertuzumab group (hazard ratio 0.69, 95% CI 0.58-0.81). Serious adverse events were reported in 115 (29%) of 396 patients who received placebo, trastuzumab, and docetaxel and 148 (36%) of 408 who received pertuzumab, trastuzumab, and docetaxel, and included febrile neutropenia, neutropenia, diarrhoea, pneumonia, and cellulitis. Overall, adverse events were similar to those reported at the primary analysis with respect to frequency, severity, and specificity.

INTERPRETATION

Our analysis shows a significant improvement in overall survival with pertuzumab, trastuzumab, and docetaxel in patients with HER2-positive metastatic breast cancer, compared with placebo, trastuzumab, and docetaxel. Since this effect was not achieved at the expense of adverse events, this regimen represents a substantial improvement on the standard of care for this population of patients.

FUNDING

F Hoffmann-La Roche, Genentech.

Cardiac tolerability of pertuzumab plus trastuzumab plus docetaxel in patients with HER2-positive metastatic breast cancer in CLEOPATRA: a randomized, double-blind, placebo-controlled phase III study

INTRODUCTION

We report cardiac tolerability of pertuzumab plus trastuzumab plus docetaxel versus placebo plus trastuzumab plus docetaxel observed in the phase III study CLEOPATRA in patients with HER2-positive first-line metastatic breast cancer (MBC).

PATIENTS AND METHODS

Left ventricular ejection fraction (LVEF) ≥ 50% and ECOG performance status of 0 or 1 were required for study entry. During the study, LVEF assessments took place every 9 weeks. Pertuzumab/placebo was given at 840 mg, then 420 mg q3w; trastuzumab was administered at 8 mg/kg, then 6 mg/kg q3w, and docetaxel was initiated at 75 mg/m(2) q3w.

RESULTS

The incidence of cardiac adverse events (all grades) was 16.4% in the placebo arm and 14.5% in the pertuzumab arm, with left ventricular systolic dysfunction (LVSD, all grades) being the most frequently reported event (8.3% versus 4.4% in the placebo and pertuzumab arm). Declines in LVEF by ≥ 10% points from baseline and to <50% were reported in 6.6% and 3.8% of patients in the placebo and pertuzumab arm, respectively. Seventy-two percent (placebo arm) and 86.7% (pertuzumab arm) of those patients recovered to a value ≥ 50%. The incidence of symptomatic LVSD was low, occurring in 1.8% (n = 7) versus 1.0% (n = 4) of patients in the placebo and pertuzumab arm. In 8/11 patients, the symptomatic LVSD had resolved at data cutoff.

CONCLUSION

The combination of pertuzumab plus trastuzumab plus docetaxel did not increase the incidence of cardiac adverse events, including LVSD, compared with the control arm in HER2-positive MBC. The majority of cardiac adverse events were reversible.

Pertuzumab plus trastuzumab plus docetaxel for metastatic breast cancer

BACKGROUND

The anti-human epidermal growth factor receptor 2 (HER2) humanized monoclonal antibody trastuzumab improves the outcome in patients with HER2-positive metastatic breast cancer. However, most cases of advanced disease eventually progress. Pertuzumab, an anti-HER2 humanized monoclonal antibody that inhibits receptor dimerization, has a mechanism of action that is complementary to that of trastuzumab, and combination therapy with the two antibodies has shown promising activity and an acceptable safety profile in phase 2 studies involving patients with HER2-positive breast cancer.

METHODS

We randomly assigned 808 patients with HER2-positive metastatic breast cancer to receive placebo plus trastuzumab plus docetaxel (control group) or pertuzumab plus trastuzumab plus docetaxel (pertuzumab group) as first-line treatment until the time of disease progression or the development of toxic effects that could not be effectively managed. The primary end point was independently assessed progression-free survival. Secondary end points included overall survival, progression-free survival as assessed by the investigator, the objective response rate, and safety.

RESULTS

The median progression-free survival was 12.4 months in the control group, as compared with 18.5 months in the pertuzumab group (hazard ratio for progression or death, 0.62; 95% confidence interval, 0.51 to 0.75; P<0.001). The interim analysis of overall survival showed a strong trend in favor of pertuzumab plus trastuzumab plus docetaxel. The safety profile was generally similar in the two groups, with no increase in left ventricular systolic dysfunction; the rates of febrile neutropenia and diarrhea of grade 3 or above were higher in the pertuzumab group than in the control group.

CONCLUSIONS

The combination of pertuzumab plus trastuzumab plus docetaxel, as compared with placebo plus trastuzumab plus docetaxel, when used as first-line treatment for HER2-positive metastatic breast cancer, significantly prolonged progression-free survival, with no increase in cardiac toxic effects. (Funded by F. Hoffmann-La Roche/Genentech; ClinicalTrials.gov number, NCT00567190.).

Recombinant human thrombopoietin augments mobilization of peripheral blood progenitor cells for autologous transplantation

This study assessed the ability of various schedules of recombinant human thrombopoietin (rhTPO) to enhance mobilization of peripheral blood progenitor cells (PBPCs) in 134 patients with cancer undergoing high-dose chemotherapy and autologous PBPC transplantation. Patients received the study drug on days 1, 3, and 5 before initiation of granulocyte colony-stimulating factor (G-CSF) 10 microg/kg/day on day 5 and pheresis starting on day 9. Randomly assigned treatments on days 1, 3, and 5 were: group 1 (n=27) placebo, placebo, rhTPO 1.5 microg/kg; group 2 (n=27) rhTPO 1.5 microg/kg, placebo, placebo; groups 3 (n=28) and 4 (n=22) rhTPO 0.5 microg/kg on all 3 treatment days; and group 5 (n=30) placebo on all 3 treatment days. After high-dose chemotherapy and PBPC transplantation, groups 1 through 4 received rhTPO 1.5 microg/kg days 0, +2, +4, and +6 with either G-CSF 5 microg/kg/day (groups 1-3) or granulocyte-macrophage colony-stimulating factor 250 microg/m(2)/day (group 4). Group 5 received placebo plus G-CSF 5 microg/kg/day. The addition of rhTPO to G-CSF increased median CD34+ cell yield/pheresis in cohorts in which rhTPO was started before day 5, with higher yields in groups 2 (2.67 x 10(6)/kg) and groups 3 and 4 (3.10 x 10(6)/kg) than in group 1 (1.86 x 10(6)/kg) or group 5 (1.65 x 10(6)/kg) (P=.006 across groups). Comparing rhTPO to placebo, higher percentages of patients achieved the minimum yield of CD34+ > or =2 x 10(6)/kg (92% v 75%; P=.050) as well as the target yield of CD34+ > or =5 x 10(6)/kg (73% v 46%; P= .041). rhTPO-treated patients required fewer phereses to achieve minimum (P= .011) and target (P= .015) CD34+ cell values. rhTPO given after transplantation did not speed platelet recovery. No neutralizing antibodies were observed. We conclude that rhTPO can safely enhance mobilization of PBPC, reduce the number of leukapheresis, and allow more patients to meet minimal cell yield requirements to receive high-dose chemotherapy with PBPC transplantation.

Recombinant human thrombopoietin (rhTPO) after autologous bone marrow transplantation: a phase I pharmacokinetic and pharmacodynamic study

Thrombocytopenia following myelotoxic therapy is a common problem and when severe (<20,000/microl) can lead to severe morbidity and mortality. Thrombopoietin (TPO) is a naturally occurring glycosylated peptide which stimulates the differentiation of bone marrow stem cells into megakaryocyte progenitor cells, induces the expression of megakaryocyte differentiation markers, promotes megakaryocyte proliferation, polyploidization and, ultimately, the formation of increased numbers of platelets in the circulation. TPO has now been produced by recombinant technology and has entered clinical trials. This open label phase I study was designed to determine the safety, tolerance and pharmacokinetics of recombinant thrombopoietin (rhTPO) when administered to patients after undergoing high-dose chemotherapy followed by autologous bone marrow transplantation. rhTPO was administered intravenously by bolus injection at doses ranging from 0.3 to 4.8 microg/kg/day every 3 days to 30 patients and 0.6 microg/kg daily to three patients. rhTPO was begun the day after marrow infusion and continued until platelet recovery to >20,000/microl. G-CSF was concomitantly administered to promote myeloid recovery. Serious adverse events or neutralizing antibodies to rhTPO were not observed during the study. Median platelet recovery after ABMT was 19 days (range, 11-41). Neither the dose nor the schedule of rhTPO appeared to have any impact upon the time course of platelet recovery. In this phase I study, rhTPO was found to be well tolerated without the development of neutralizing antibodies and without compromising neutrophil recovery. Platelet recovery was similar for all doses studied warranting further evaluation in phase II and III trials designed to test for platelet recovery efficacy.

Interleukin-2 therapy after bone marrow or stem cell transplantation for hematologic malignancies

PURPOSE

Autologous or allogeneic bone marrow transplantation (BMT) or stem cell transplantation (SCT) for advanced hematologic malignancies is associated with a high relapse rate. It has been postulated that recombinant interleukin-2 (rIL-2) administered as consolidative immunotherapy early after BMT or SCT, at a time of minimal residual disease, might reduce the relapse rate. We review here preliminary results from a series of studies designed to investigate the safety, immunomodulatory effects, and clinical benefits of rIL-2 therapy following autologous and allogeneic BMT and SCT.

PATIENTS AND METHODS

Patients with hematologic malignancies underwent autologous or allogeneic BMT or SCT and received rIL-2 by continuous intravenous infusion a median of 33 to 56 days later. In all trials, the rIL-2 regimen consisted of a moderate induction dose for 4 to 5 days in the hospital, 4 to 6 days of rest, and a low maintenance dose for 10 days in the outpatient setting. A phase I trial of Roche rIL-2 after autoBMT, a feasibility trial of autologous lymphokine-activated killer cells with rIL-2, and another phase I/II trial of Chiron rIL-2 after autoBMT were performed. A similar phase I trial of IL-2 after alloBMT was also performed in children with acute leukemia beyond first complete remission.

RESULTS

An rIL-2 regimen has been identified that can be tolerated early after transplantation. Administration of this rIL-2 regimen induces marked increases in CD3+CD8+ T lymphocytes and CD3-CD56+ natural killer cells and enhances their antitumor cytolytic activity. Encouraging but somewhat inconsistent clinical outcomes were noted in phase I/II trials in patients with lymphoma and acute myeloid leukemia.

CONCLUSIONS

The results of phase I/II trials are sufficiently encouraging to justify prospectively randomized phase III trials to determine whether rIL-2 after autologous SCT will reduce the rate of posttransplantation relapse and improve survival in patients with advanced hematologic malignancies.

Steroid-refractory cutaneous graft-versus-host disease after transplantation of haploidentical parental CD34+ cells in children with Down's syndrome and recurrent acute leukemia

PURPOSE

This study evaluated the feasibility of performing haploidentical CD34+ selected transplants for children with Down's syndrome (DS) and recurrent leukemia.

PATIENTS AND METHODS

Within a cohort of 15 children, two patients had DS. Transplantation of CD34+ cells from haploidentical parents was performed after the children were conditioned with fractionated total body irradiation, cyclophosphamide, and antithymocyte globulin (ATG). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and a short course of methotrexate.

RESULTS

The preparative regimen was well tolerated, and engraftment of polymorphonuclear cells and platelets took place promptly (by day 20) in both patients with DS. However, both patients with DS experienced severe grade IV GVHD that was limited to the skin and was refractory to salvage with high-dose methylprednisolone therapy. In one patient, GVHD responded to second-line salvage therapy with ATG, but the patient died on day 234 from leukemic relapse. The second patient had GVHD that did not respond to ATG and died of multisystem organ failure and refractory GVHD on day 44. Two of two DS patients had steroid refractory severe acute GVHD of the skin, while only one of 11 evaluated and identically treated non-DS patients had severe GVHD (p < 0.05).

CONCLUSION

These observations in patients who underwent mismatched bone marrow transplantation suggests that patients with DS have an increased risk of severe acute GVHD of the skin in this context.

Interleukin-2 after autologous stem cell transplantation for hematologic malignancy: a phase I/II study

The success of autologous stem cell transplantation (ASCT) for hematologic malignancy is limited largely by a high relapse rate. It is postulated that IL-2 administered after ASCT may eliminate minimal residual disease and thereby reduce relapses. A phase I/II study was performed to identify a regimen of IL-2 (Chiron) that could be given early after ASCT in phase III trials. In the phase I study, beginning a median of 46 days after ASCT for hematologic malignancy, cohorts of three to four patients received escalating doses of 'induction' IL-2 of 9, 10, or 12 x 10(6) IU/m2/day for 4 or 5 days by continuous i.v. infusion (CIV), followed by a 4-day rest period, and then 1.6 x 10(6) IU/m2/day of maintenance IL-2 by CIV for 10 days. The maximum tolerated dose (MTD) of induction IL-2 was 9 x 10(6) IU/m2/day x 4. In the phase II study, 52 patients received the MTD. Eighty percent of patients completed induction IL-2. Most patients exhibited some degree of capillary leak. One patient died of CMV pneumonia and one died of ARDS. Maintenance IL-2 was well tolerated. In the phase I/II study, 16 of 31 patients with non-Hodgkin lymphoma (NHL), 3/8 with Hodgkin disease (HD), 4/17 with AML, and 4/5 with ALL remain in CR. Two of six multiple myeloma (MM) patients remain in PR. Although the regimen of IL-2 identified had significant side-effects in some patients, it was well tolerated in the majority of patients. Phase III prospectively randomized clinical trials are in progress to determine if this IL-2 regimen will decrease the relapse rate after ASCT for AML and NHL.

Close simulation of acute graft-versus-host disease by interleukin-2 administered after autologous bone marrow transplantation for hematologic malignancy

The high relapse rate of hematologic malignancy treated with autologous bone marrow transplantation (ABMT) may reflect the absence of a graft-versus-leukemia (GVL) effect usually associated with graft-versus-host disease (GVHD). The purpose of this study was to determine whether administration of interleukin-2 (IL-2) early after ABMT might induce or exacerbate acute skin GVHD. Fourteen patients at high risk for post-transplant relapse, eight with NHL and six with AML > or = first relapse, were conditioned with chemotherapy and total body irradiation (13) or chemotherapy alone (1), and received purged (10) or unpurged (4) marrow. A median of 35 days (range 25-58) after ABMT, they received a 5-day induction course of Roche IL-2 (9 x 10(6) U/m2/day) followed by apheresis, reinfusion of LAK cells, and a 10-day maintenance course of IL-2 (0.9 x 10(6) U/m2/day), all by continuous i.v. infusion. Serial skin biopsies were obtained before and after IL-2 therapy and were read blindly. Patients were studied prospectively for the development of acute cutaneous GVHD as reflected by rash ( > or = 25% body surface area), skin biopsy ( > or = grade II histologic changes) and T cell infiltration as assessed by staining of the biopsy with antibodies UCHL-1 and TIA-1. No patient had a rash before IL-2 therapy, but 12 of 14 (85%) developed a rash during the IL-2 induction course. Before IL-2 therapy, biopsies from three of 10 patients (30%) revealed histologic GVHD; after induction IL-2, biopsies from 11 of 14 patients (79%) revealed grade II acute GVHD. Biopsies from all patients with histologic GVHD after IL-2 therapy contained TIA-1 positive T cells. HLA-DR was negative in the keratinocytes of these paraffin-embedded sections. One patient died early of sepsis, one patient required and responded to topical corticosteroids and 12 had spontaneous resolution of the rash. Six patients relapsed at 3-13 months, while seven remain in complete remission 32+ to 41+ months after ABMT. The results demonstrate that IL-2 therapy after ABMT can induce effects which histologically and clinically mimic cutaneous acute GVHD in most patients. Prospective, randomized trials of IL-2 vs observation after transplantation of autologous marrow or stem cells for high-risk NHL and AML have been initiated which may allow us to determine whether this phenomenon is associated with a clinical GVL effect as reflected by a decreased relapse rate.

Phase I trial of interleukin-2 after unmodified HLA-matched sibling bone marrow transplantation for children with acute leukemia

Allogeneic bone marrow transplantation (BMT) for advanced acute leukemia is associated with a high risk of relapse. It is postulated that interleukin-2 (IL-2) administered after BMT might induce or amplify a graft-versus-leukemia effect and thereby reduce the relapse rate. To identify an IL-2 regimen for testing this hypothesis, a phase I trial of IL-2 (Roche) was performed in children in complete remission (CR) without active graft-versus-host disease (GVHD) off immunosuppressive agents after unmodified allogeneic matched-sibling BMT for acute leukemia beyond first remission. Beginning a median of 68 days after BMT, 17 patients received escalating doses of induction IL-2 (0.9, 3.0, or 6.0 x 10(6) IU/m2/d representing levels I, II, and III) for 5 days by continuous intravenous infusion (CIV). After 6 days of rest, they received maintenance IL-2 (0.9 x 10(6) IU/m2/d) for 10 days by CIV infusion. Levels I and II were well-tolerated, but, of 6 patients at level III, 1 developed pulmonary infiltrates, 1 developed hypotension (both resolved), and 1 died of bacterial sepsis and acute respiratory distress syndrome. Grade II acute GVHD developed in 1 patient at level I and 1 at level III. The maximum tolerated dose of induction IL-2 was level II. IL-2 induced lymphocytosis, with an increase in CD56+ and CD8+ cells. Ten patients remain in CR at 5+ to 67+ months. Thus, a regimen of IL-2 has been identified that did not induce a high incidence of acute GVHD when administered to children after unmodified allogeneic BMT. Its clinical activity will be assessed in a phase II trial.

Immunotherapy with interleukin 2 with or without lymphokine-activated killer cells after autologous bone marrow transplantation for malignant lymphoma: a feasibility trial

Early relapse remains a major challenge after autologous bone marrow transplant for malignant lymphoma (ML). It is postulated that consolidative immunotherapy with interleukin 2 (IL-2) with or without lymphokine-activated killer (LAK) cells administered after autologous bone marrow (ABMT) or peripheral blood stem cell transplantation (PBSCT) for ML might eradicate residual disease and reduce relapse rates. A previous trial identified an IL-2 regimen that could be administered early after ABMT. This paper presents the clinical results of 16 patients with ML, who participated in a study to determine whether LAK cells could be administered after ABMT with this IL-2 regimen, as well as 6 patients who received IL-2 alone after ABMT or PBSCT. Seventeen patients with non-Hodgkin's lymphoma (NHL), and 5 with Hodgkin's disease (HD), underwent ABMT (20 patients) or PBSCT (2 patients). At the time of transplantation, 7 patients were in untreated or chemotherapy-sensitive first relapse, 3 were in CR2, and 12 were beyond CR2. Beginning 22-85 days (median 43) after ABMT/PBSCT, patients received IL-2 at 3.0 x 10(6) U/m2/day by continuous infusion days 1-5 of the IL-2 protocol. On protocol days 7-9 the first 16 patients underwent apheresis for LAK cell generation. The cells were cultured in IL-2 for 5 days and were infused on days 12-14. Low-dose IL-2 (0.9 x 10(6) IU/m2/day) was administered on days 12-21 in the outpatient department. Patients received a median of 148 (62-279) x 10(9) LAK cells. LAK cell infusions were associated with transient fevers, chills and dyspnea in most patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Cataracts after bone marrow transplantation: long-term follow-up of adults treated with fractionated total body irradiation

PURPOSE

To determine the risk of, and risk factors for, developing cataracts after bone marrow transplantation.

METHODS AND MATERIALS

Four hundred and ninety-two adults who underwent bone marrow transplantation in Seattle were followed for 2 to 18 (median, 6) years. Before transplantation, patients received a preparative regimen of chemotherapy plus total body irradiation (TBI) (n = 407) or chemotherapy alone, without TBI (n = 85). TBI was administered in a single dose of 10 Gy (n = 74) or in fractionated doses totaling 12-15.75 Gy (n = 333). The risk of cataracts was determined for groups of patients with respect to the type of preparative regimen received and other pretransplant and posttransplant variables.

RESULTS

One hundred and fifty-nine patients (32%) developed cataracts between 0.5 to 11 (median, 2.3) years after transplantation. The probability of cataracts at 11 years after transplantation was 85%, 50%, 34%, and 19% for patients receiving 10 Gy of single-dose TBI, > 12 Gy fractionated TBI, 12 Gy fractionated TBI, and no TBI, respectively (p < 0.0001). Among those developing cataracts, the severity was greater in patients after single-dose TBI (59% probability of surgical extraction) than after > 12 Gy fractionated TBI, 12 Gy fractionated TBI, or no TBI (33%, 22% and 23%, respectively). Patients given corticosteroids after transplant had a higher probability of cataracts (45%) than those without steroids (38%) (p < 0.0001). In a proportional hazards regression model, the variables that were correlated with an increased probability of cataracts were single-dose TBI (relative risk (RR) = 2.46) and steroid therapy (RR = 2.34), while a decreased probability of cataracts was correlated with a nonTBI preparative regimen (RR = 0.41). The yearly hazard of developing cataracts in recipients of single-dose TBI was highest during the third year after transplantation, while in recipients of fractionated TBI, the hazard was distributed among years one through seven. The probability of cataracts in all groups reached a plateau at 7 years after transplantation, after which the development of cataracts was extremely unlikely.

CONCLUSION

TBI is the major risk factor for developing cataracts after BMT. Single-dose TBI results in the highest risk of cataracts. However, the risk of cataracts in recipients of fractionated-TBI is significantly higher than in patients who receive no TBI. In addition to TBI, steroid therapy is an independent risk factor for cataracts after BMT.

Phase Ib trial of pentoxifylline and ciprofloxacin in patients treated with interleukin-2 and lymphokine-activated killer cell therapy for metastatic renal cell carcinoma

The dose of interleukin 2 (IL-2) which can be administered to cancer patients is limited largely by a capillary leak syndrome. Pentoxifylline (PTX) is a methylxanthine which reduces IL-2 toxicity in animals. Ciprofloxacin (Cipro) modifies the metabolism of methylxanthines and, when coadministered with PTX, increases levels of PTX and certain of its metabolites. We conducted a phase Ib trial in patients receiving IL-2 and lymphokine-activated killer cell (LAK) cell therapy for metastatic renal cell carcinoma to identify the maximum tolerated dose of PTX which could be coadministered with Cipro in this setting. Eighteen patients received IL-2 (Roche) by continuous infusion at 6 x 10(6) units/m2/day on days 1-5 and underwent leukapheresis on days 7-9. LAK cells were infused on days 12-14. IL-2 was administered at 2 x 10(6) units/m2/day on days 10-20. Cohorts of patients received PTX at 2.5 (n = 3), 3.1 (n = 6), 3.9 (n = 6), and 4.9 (n = 3) mg/kg by 30 min i.v. infusion every 4 h on days 0-5 and 10-20 and Cipro (500 mg p.o. every 12 h) on days 1-5 and 10-20. Toxicity was compared with that observed in 33 historical control patients who received 37 cycles of an identical regimen of IL-2/LAK without PTX/Cipro. PTX at 2.5-3.9 mg/kg and Cipro were well tolerated. The maximum tolerated dose of PTX was 3.9 mg/kg. Dose-limiting emesis (n = 1) and atrial fibrillation (n = 2) occurred at 4.9 mg/kg and were reversible. Two complete, one partial and one minor, responses were observed. Patients treated with 3.9 mg/kg PTX received 95.0% of the planned dose of IL-2 as compared to 72.8% in the control patients (P < 0.025), primarily due to a lower incidence of azotemia and metabolic acidosis in PTX/Cipro recipients than had been seen in the historical control patients. The results of this study demonstrate that PTX/Cipro can be administered to patients receiving IL-2/LAK without apparent loss of therapeutic efficacy. Moreover, PTX/Cipro recipients exhibited less toxicity than historical controls. Therefore, treatment with PTX/Cipro may allow delivery of higher doses of IL-2, which might induce more responses in IL-2-responsive tumors and regression of tumors unresponsive to conventional doses of IL-2.

Lymphokine-activated killer (LAK) precursor cell activity is present in infused peripheral blood stem cells and in the blood after autologous peripheral blood stem cell transplantation

Immunotherapy with interleukin-2 (IL-2) early after peripheral blood stem cell transplantation (PBSCT) is being considered as a potential way to eradicate minimal residual disease. The aim of this study was to determine whether lymphocytes which can acquire lymphokine-activated killer (LAK) cell activity are present in PBSC and in the blood of patients after PBSCT. Fresh and cryopreserved G-CSF-mobilized PBSC from eight patients were incubated with IL-2 (1000 U/ml) for 3-6 days and then tested for LAK activity as measured by lysis of the Daudi cell line. LAK activity was present in both fresh and cryopreserved PBSC, with mean lysis of 32% and 36%, respectively, at an effector:target (E:T) ratio of 50:1. To assess the reconstitution of LAK precursor activity after PBSCT, peripheral blood (PB) obtained from eight other patients 15-60 days after PBSCT was similarly tested. LAK activity was detected in PB from every patient (mean lysis of 38% at an E:T ratio of 12.5:1). PB from patients after PBSCT contained a higher percentage of CD8+ cells and CD56+ cells than did PB from 9 normal controls (47.2% vs. 21.4% CD8+ cells, P < 0.005 and 28.6% vs. 8.6% CD56+ cells, P < 0.0005). Moreover, PB from 4 of 5 patients tested after PBSCT exhibited a high percentage of cells expressing p75, the intermediate affinity IL-2R. Thus, precursor cells capable of acquiring IL-2-inducible LAK activity are present in PBSC and are rapidly reconstituted after PBSCT. The findings provide a rationale for testing IL-2 as a way of decreasing relapses after PBSCT.

Induction by interleukin-7 of lymphokine-activated killer activity in lymphocytes from autologous and syngeneic marrow transplant recipients before and after systemic interleukin-2 therapy

Therapy with recombinant lymphokines after autologous bone marrow transplantation (ABMT) is being explored as a way to prevent relapse. Lymphokine therapy may exert an antitumor effect through a variety of mechanisms, including the induction of lymphokine-activated killer (LAK) cell cytotoxicity. We tested the ability of interleukin-7 (IL-7) to induce LAK cytotoxicity in peripheral blood mononuclear cells (PBMC) from healthy subjects and from patients early after ABMT. LAK activity was defined as lysis of Daudi by PBMC after incubation with IL-7 at 10 to 100 ng/mL or IL-2 at 1000 U/mL. PBMC from four healthy subjects were cultured with either IL-7 or IL-2. IL-7 induced LAK activity in two of the four, whereas IL-2 induced LAK activity in all four. The median percent lysis (effector-to-target ratio [E:T] 40:1) with IL-7 (23%) was lower than with IL-2 (67%). PBMC were obtained from 15 patients 27 to 84 days after autologous (n = 13) or syngeneic (n = 2) bone marrow transplantation (BMT) and tested for IL-7-induced LAK activity. Eleven exhibited significant activity (10% to 77% lysis at E:T 40:1). In contrast to the results in PBMC from normal subjects, in PBMC from ABMT patients IL-7 induced LAK activity of a magnitude similar to that induced by IL-2. Studies were also performed on PBMC from eight patients who had received IL-2 after ABMT (3.0 x 10(6) U/m2/d) for 4 days by continuous intravenous (IV) infusion. In seven of the eight patients, IL-7 induced significant LAK activity, which was higher than that seen in PBMC from ABMT patients who had not received IL-2. Thus, IL-7 reproducibly induced significant LAK activity in cells obtained early after autologous or syngeneic BMT. Indeed, such LAK activity was comparable quantitatively to that induced by IL-2. Finally, IL-7 induced an even greater LAK activity in vitro in PBMC obtained after ABMT and preactivated in vivo by IL-2 therapy. The results suggest that IL-7 may have a potential immunotherapeutic role, alone or with IL-2, after ABMT.

Interleukin-2 with or without lymphokine-activated killer cells as consolidative immunotherapy after autologous bone marrow transplantation for acute myelogenous leukemia

IL-2 with or without autologous lymphokine-activated killer (LAK) cells, administered early after ABMT for AML may eradicate residual disease and reduce relapses. This paper reports 14 patients who received IL-2 or IL-2 plus LAK cells after ABMT for AML in first relapse or at a later stage, in two separate trials. Patients with AML in first relapse (n = 9), second CR (n = 3) or second relapse (n = 2) underwent ABMT after busulfan (BU), CY and total body irradiation (n = 11) or BU/CY alone (n = 3), with marrow that was (n = 6) or was not (n = 8) purged with 4-HC. In a previously-reported Phase I trial, eight patients received IL-2 (Roche) by continuous infusion at 0.3-3.0 x 10(6) U/m2/day x 5 days and, after 6 days of rest, 0.3 x 10(6) U/m2/day x 10 days. In a subsequent trial, five patients received IL-2 at 3.0 x 10(6) U/m2/day x 5 days, underwent leukapheresis for 3 days and received their LAK cells plus IL-2 (0.3 x 10(6) U/m2/day x 10 days). A sixth patient received only 2 days of IL-2, developed sepsis and died of multiorgan failure. All other patients had mild to moderate toxicity which was reversible. All patients developed neutrophilia, lymphocytosis and thrombocytopenia. IL-2 with or without LAK therapy was initiated 21-91 days (median 51 days) after ABMT. Severe thrombocytopenia (< 10 x 10(9)/l) occurred during the apheresis days.(ABSTRACT TRUNCATED AT 250 WORDS)

Autologous marrow transplantation for patients with acute myeloid leukemia in untreated first relapse or in second complete remission

PURPOSE

This study compares outcomes of autologous bone marrow transplantation (ABMT) in patients with acute myeloid leukemia (AML) in untreated first relapse (REL1) or in second complete remission (REM2).

PATIENTS AND METHODS

Forty-seven patients with AML in REL1 (n = 21) or in REM2 (n = 26) were treated with busulfan (BU) and cyclophosphamide (CY) with or without total-body irradiation (TBI) followed by ABMT. All REL1 patients and four REM2 patients had marrow stored during first remission (REM1). Twenty-seven had marrow stored with and 20 without treatment in vitro with 4-hydroperoxycyclophosphamide (4-HC). Eighteen patients received BU and CY and 29 received BU, CY, and TBI. REL1 patients relapsed within a median of 9 months (range, 2 to 26) after marrow harvest and were transplanted a median of 30 days (range, 9 to 87) from detection of relapse.

RESULTS

With a median follow-up of 2.1 years (range, 0.4 to 5.3), 19 patients survive in remission (10 of 21 in REL1; nine of 26 in REM2). The actuarial probabilities of relapse-free survival at 2 years for patients transplanted in REL1 and REM2 were 45% +/- 22% and 32% +/- 18%, respectively (P = .33). The corresponding probabilities of relapse were 30% +/- 26% and 44% +/- 23%, respectively (P = .45). No conclusions could be drawn about the benefits of adding TBI to BU plus CY. There were no significant differences in neutrophil or platelet recovery or in posttransplant probabilities of relapse and nonrelapse mortality between patients who received marrow treated or not treated with 4-HC.

CONCLUSION

These results suggest that ABMT may produce long-term leukemia-free survival in approximately one third of patients with AML in REL1 or in REM2. There is no apparent clinical advantage in attempting to obtain second remissions in relapsed patients before ABMT if marrow has been cryopreserved during REM1. Although a strategy of transplantation in REL1 has advantages for the patient, such an approach involves the storage of marrow, which may not be used, and is impractical without the coordinated support of the treating physician, the patient, and the marrow transplant center.

Adverse reactions to intravenous contrast media in patients treated with interleukin-2

Seventy patients consecutively admitted to a single institution were treated with high-dose interleukin-2 (IL-2) and analyzed for determining the incidence and risk factors associated with reactions to i.v. contrast media. Patients with metastatic renal cancer (n = 44) or melanoma (n = 26) received 74 cycles of IL-2 administered at 2 to 6 x 10(6) U/m2/d for 10-21 days either alone or with lymphokine-activated killer (LAK) cells or tumor-infiltrating lymphocytes (TILs). Seventy-four computed tomography (CT) scans were performed before administration of IL-2; and 74, 59, and 35 CT scans were performed, respectively, 2, 6, and 10 weeks after administration of IL-2. Of the 168 scans performed after therapy with IL-2, non-ionic media were used in 110 and ionic media were used in 58. There were no reactions before administration of IL-2, but there were nine reactions after therapy with IL-2. Reactions to contrast media occurred 1-4 hours after media infusion and included fever, chills, emesis, diarrhea, rash, wheezing, hypotension, edema, and oliguria. Hospitalization was required in seven cases, including intensive care unit support in four, but all patients recovered fully. Contrast reactions were more frequent 2 weeks after therapy with IL-2 (eight of 74 scans, 11%) compared with 6 weeks after IL-2 (one of 59 scans, 1.7%), but the difference was not statistically significant (McNemar's test). Six patients who reacted to contrast 2 weeks after IL-2 treatment received contrast 4 weeks later: five had no reaction and only one experienced a reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of pentoxifylline on the generation of human lymphokine-activated killer cell cytotoxicity

Pentoxifylline (PTX) is a methylated xanthine that has been shown to reduce the toxicity of Interleukin-2 (IL-2) therapy in animal models, possibly by inhibiting secretion of tumor necrosis factor-alpha. However, the use of PTX to reduce IL-2 toxicity in cancer patients would be advantageous only if PTX did not abrogate antitumor effector mechanisms. We therefore tested the effects of PTX on the induction of lymphokine-activated killer (LAK) cell reactivity in human peripheral blood mononuclear cells (PBMCs). LAK precursor and effector activity were defined as lysis of Daudi cells by PBMCs after incubation with IL-2 at 1,000 U/ml (LAKp) or without incubation (LAKe). PBMCs from four healthy subjects were cocultured for 5 days with IL-2 and PTX (0-1.0 mM). LAKp was inhibited in a PTX dose-dependent manner, as the mean % lysis at an E:T ratio of 50:1 was 62, 43, and 8% in the presence of 0, 0.1, and 1.0 mM PTX, respectively. To determine the effect of in vivo PTX on LAKp activity, four healthy subjects were tested after treatment with PTX at 2 g/day for 3 days. LAKp activity was detected in all four and was not inhibited by autologous serum containing PTX and biologically active metabolites. Because lymphocytes "preactivated" by IL-2 in vivo may respond to PTX differently than resting cells, two patients were tested after a 5 day infusion of IL-2 at 6 x 10(6) U/m2/day. PBMCs from both displayed LAKp activity, with far less inhibition by PTX than in resting cells (4, 17, and 37% inhibition at 0.05, 0.1, and 1.0 mM, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Prolonged continuous intravenous infusion interleukin-2 and lymphokine-activated killer-cell therapy for metastatic renal cell carcinoma

PURPOSE

Two consecutive protocols of continuous intravenous (CIV) infusion interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells were carried out in patients with metastatic renal cell carcinoma (RCC) to determine the response rate and toxicity.

PATIENTS AND METHODS

In both protocols, patients received induction IL-2 at 6 x 10(6) U/m2/d on days 1 to 5, and underwent leukapheresis on days 7 to 9 at the peak of rebound lymphocytosis. LAK cells were generated by a 5-day incubation with IL-2 at 1,000 U/mL, and were infused on days 12 to 14. For the first 20 patients (protocol A), maintenance IL-2 was administered at 6 x 10(6) U/m2/d on days 12 to 16. On the assumption that less IL-2 might be required to maintain rather than to induce LAK activity, and that a longer duration of maintenance IL-2 might enhance LAK survival and function in vivo, the protocol for the subsequent 22 patients (protocol B) was altered so that the maintenance phase consisted of a lower dose of IL-2 (2 x 10(6) U/m2/d) administered for a longer period of time (days 10 to 20).

RESULTS

In protocol A, there were two complete responses (CRs) and three partial responses (PRs), for a total response rate of 25%. One PR was surgically converted into a CR. The durations of the CRs are 36+, 18+, and 18+ months. Hypotension and capillary leak were most severe during maintenance, which limited the median duration of maintenance IL-2 to 4 days. In protocol B, no patient experienced severe hypotension, and the median duration of maintenance IL-2 was 9 days. Two patients exhibited a CR and seven a PR, for a total response rate of 41%. Two PRs were surgically converted to CRs. The durations of CR are 14+, 9+, 6+, and 5+ months. In both protocols, the CIV induction regimen resulted in marked rebound lymphocytosis (mean, 11,097/microL) and LAK-cell yield (mean, 18.1 x 10(10)). The cumulative response rate was 14 of 42 patients, or 33% (95% confidence interval, 19% to 47%).

CONCLUSION

These results demonstrate that both protocols of CIV IL-2 plus LAK cells have substantial antitumor activity, and that a longer maintenance phase of IL-2 at a lower dose is associated with significantly less toxicity without a loss of therapeutic efficacy.

Observer variability in the pulmonary examination

Observer variability in the pulmonary examination was assessed by having four blindfolded observers (two medical students and two pulmonary physicians) twice examine 31 patients with abnormal pulmonary findings. Examiners were consistent in the repetitive detection of pulmonary abnormalities in 74-89% of the examinations; conversely, 11-26% of the time they disagreed with themselves. Although pulmonary specialists recorded fewer (55% of observations) abnormal findings than did medical students (74%), they were significantly (p = 0.008) less self-consistent than were the students. There was no clear trend in agreement between examiners (kappa = 0.20-0.49). Each examiner's findings were compared with those of physicians specially trained in pulmonary examination. Dichotomous variables (wheezes, crackles, rubs) were more reliably detected (kappa = 0.30-0.70) than graded variables (tympany, dullness, breath sound intensity), where kappa = 0.16-0.43. The authors suggest that dichotomous variables deserve greatest clinical reliance; that time in training, alone, does not improve clinical performance; and that there is a disconcertingly large amount of inter- and intraobserver disagreement in this fundamental clinical task.

Influence of cimetidine on verapamil kinetics and dynamics

The kinetics and dynamics of single doses of verapamil (10 mg iv and 120 mg by mouth) were followed in eight subjects on oral cimetidine (300 mg every 6 hr) and placebo. Cimetidine had no effect on intravenous verapamil kinetics but induced a significant rise in oral verapamil bioavailability. Other kinetic parameters of verapamil were not altered by cimetidine. Verapamil induced a significant slowing of atrioventricular conduction (39.8 msec intravenous; 24.5 msec oral). Although there was a significant increase in oral verapamil bioavailability, after cimetidine, there was no change in PR interval prolongation with either oral or intravenous verapamil. Our data demonstrate the importance of correlating measurable drug effects with kinetic studies when drug interactions are studied and their clinical significance is assessed.

Characterization of an oligopeptide chemoattractant receptor on human blood monocytes using a new radioligand

The study of chemoattractant receptors on human monocytes had been limited by the lack of a radioligand suitable for use with the small numbers of cells routinely available from human donors. A new synthetic oligopeptide radioligand f[35S]met-leu-phe, with a higher specific radioactivity than was available with the tritiated compound, was used to characterize a chemoattractant receptor on freshly isolated human blood monocytes. These cells bind f[35S]met-leu-phe with a dissociation constant (KD) of 30.2 +/- 5.6 nM and contain 84,000 +/- 11,300 receptors per cell. f[35S]met-leu-phe does not bind specifically to blood lymphocytes. The specificity of the oligopeptide receptor on monocytes is indistinguishable from the oligopeptide chemoattractant receptor on human polymorphonuclear leukocytes. Using f[35S]met-leu-phe, it will now be feasible to study the chemotactic peptide receptor on small numbers of partially purified peripheral blood monocytes from patients with defects of immune function.