Phase 1/2 study of zilovertamab and ibrutinib in mantle cell lymphoma (MCL) or chronic lymphocytic leukemia (CLL)

7520

Background: Zilovertamab (Zilo) is a humanized monoclonal antibody that inhibits the tumor promoting activity of ROR1 and has demonstrated additive/synergistic activity with many anti-cancer agents, including ibrutinib (Ibr). Methods: Patients (Pts) with relapsed or refractory (RR) MCL or treatment-naïve (TN) or RR CLL were enrolled. In Part 1 (Dose Escalation), multiple doses were examined. Zilo 600 mg IV starting q2wks x3 then q4wks + Ibr qD was selected as the recommended dosing regimen for use in Part 2 (Expansion) and Part 3 (CLL only, Zilo+Ibr vs. Ibr alone). Results: As of 18Jan2022 data cutoff, 26 evaluable RR MCL pts, including pts who received prior Ibr (5) or auto-SCT (7), and 34 evaluable CLL pts (12 TN and 22 RR) were enrolled into Parts 1&2. In Part 3, 22 evaluable pts were randomized (2:1) to receive either Zilo+Ibr (15) or Ibr (7). Safety: Treatment-emergent adverse events (TEAEs) (≥30%, N = 84), regardless of relationship, included fatigue (41.7%), contusion (39.3%), and diarrhea (38.1%). Most common (≥5%) Grade ≥3 TEAEs included hypertension (10.7%), pneumonia (7.1%), atrial fibrillation, fatigue, and neutropenia (all 6.0%). Grade ≥3 neutrophil decrease observed in 9.4% or 17.6%, platelet decrease in 12.5% or 2.9%, or hemoglobin decrease in 9.4% or 0% of pts with MCL or CLL, respectively in Parts 1&2. Investigators scored TEAEs as due to Ibr in 78.1% or 85.3%, or to Zilo in 15.6% or 23.5% of pts with MCL or CLL, respectively. Efficacy (MCL): Objective response rate (ORR) was 80.8% (34.6% CR, 46.2% PR). ORR for pts with prior Ibr was 80% (2CR, 2PR) and median duration of response (mDOR) was 13.7 months (M) (95%CI: 11.93, NE). ORR was 100% in pts who had prior SCT+/- CAR-T (5CR, 2PR), and mDOR was 34.1 M (95% CI 13.84, NE). Overall median PFS (mPFS) was 35.9 M (95% CI: 17.3, NE) at median follow-up of 15.0 M. For MCL pts with TP 53 aberrancy (6), Ki67 > 30% (13), ≥ 3 prior lines of therapies (4), blastoid histology (3), bulky disease ≥5 cm (4), intermediate MIPIb (6), or high MIPIb (11), the mPFS (in M) was 17.3 (95% CI: 2.85, NE), Not Reached (NR) (95% CI: 2.85, NE), 35.9 (95% CI: 16.52, NE), NR (min 9.18, max 27.87), 26.6 (95% CI: 0.03, NE), 35.9 (min 8.30, max 35.9) or 16.5 (95% CI: 2.72, NE). Efficacy (CLL): In Parts 1&2 ORR was 91.2% (8.8% CR, 82.3% PR/PR-L), and 8.8% had stable disease (SD). At median follow-up of 31.4 M, mDOR was 33.5 M and mPFS was NR (95% CI: 36.3, NE); the mPFS (in M) for pts with 1, 2, or ≥ 3 prior therapies was NR (min 19.3, max 41.3), NR (min 31.3, max 36.8) or 36.3 (95% CI: 15.7, NE). At median follow-up of 21.1 M in Part 3, mPFS was NR for TN or RR in both Zilo+Ibr and Ibr arms. Conclusions: Zilo+Ibr is well-tolerated. Striking responses were observed in MCL pts, with mPFS of 35.9 M (95% CI: 17.3, NE) and CR of 34.6%, which compares favorably to mPFS of 12.8 M (95% CI 8.5, 16.6) and CR of 20% reported for single agent Ibr (Rule 2017). For CLL, ORR and PFS compare very favorably to Ibr monotherapy data (Byrd 2019). Clinical trial information: NCT03088878.

Phase 1/2 study of cirmtuzumab and ibrutinib in mantle cell lymphoma (MCL) or chronic lymphocytic leukemia (CLL)

7556

Background: Cirmtuzumab (Cirm) is a humanized monoclonal antibody that inhibits the tumor promoting activity of ROR1 and had demonstrated additive/synergistic activity with many anti-cancer agents including ibrutinib (Ibr). Methods: Patients (Pts) with relapsed or refractory (RR) MCL or treatment naïve (TN) or RR CLL were enrolled. In Part 1 (Dose Escalation), doses of Cirm IV q2wks x5 then q4wks of 2-16 mg/kg and 300 or 600 mg were examined. Safety of Cirm alone was assessed during the first 28 days, then Ibr was started at approved doses for each indication. Cirm 600 mg IV q2wks x3 then q4wks in combination with Ibr starting day 0 was chosen as the recommended dosing regimen for use in Part 2 (Expansion) and Part 3 (CLL only, Cirm/Ibr vs. Ibr alone). Results: Twelve evaluable MCL pts were enrolled into Part 1, and 5 into Part 2. Median number of prior regimens was 2 (1-5), including pts relapsing after Ibr (4), auto-SCT (3), auto-SCT/ allo-SCT (1), auto-SCT/CAR-T (1). In CLL, 34 evaluable pts (12 TN and 22 RR) enrolled into Part 1 (18) or Part 2 (16). At least 74% of CLL pts in Parts 1 and 2 were high risk as determined by unmutated IGHV, del17p, and/or del11q. In Part 3, 22 evaluable pts received Cirm/Ibr (15) or Ibr (7). As of the 30OCT2020 safety cut-off for MCL and CLL, common TEAEs (all grades) included diarrhea (41%), contusion (39%), fatigue (39%), URI (31%), hypertension (25%) arthralgia (23%). Grade ≥3 neutropenia was 13% and thrombocytopenia 1%. There were no Cirm dose reductions or discontinuations for toxicity. Overall, Cirm did not appear to negatively impact the safety of Ibr. Efficacy (MCL): As of the 02FEB2021 efficacy cutoff, the best response of 17 evaluable pts in Parts 1 and 2 included an objective response rate (ORR) of 82%, 41% CR/CMR, 41% PR, 12% SD, and 6% PD. CR/CMR remain durable from 8-28+ mos. Most responses occurred rapidly after ̃3 mos of Cirm/Ibr. Notably, responses were achieved in all pts who received prior SCT+/- CAR-T (4CR, 1PR) or prior Ibr (2CR, 2PR). At a median follow-up of 14.6 mos, the median PFS (mPFS) had not been reached (NR) (95% CI: 17.5, NA). Efficacy (CLL): The best response of 34 evaluable pts in Parts 1 and 2 included 91% ORR, 3% CR, 88% PR/PR-L, 9% SD, 0% PD. In Part 3, both arms achieved 100% ORR (all PRs). At a median follow-up of 20.2 mos, the mPFS was NR (95% CI: NA, NA), and the PFS estimate at 24 months was 95% for R/R, and 87% for TN, respectively, for evaluable CLL pts receiving Cirm/Ibr. Conclusions: Cirm/Ibr is a well-tolerated, active regimen in both MCL and CLL. For MCL, the mPFS of NR (95% CI: 17.5, NA) and CRR (41%), with all CRs remaining without PD, compare favorably to mPFS of 12.8 mos (95% CI 8.5-16.6) and CRR (20%) reported for single agent Ibr (Rule 2017). For CLL, the high ORR and PFS are encouraging, particularly for RR CLL. The study is ongoing, with MCL enrollment expanded to study Cirm + Ibr in pts who have had a suboptimal response to an Ibr regimen, or who have failed other approved BTKi agents. Clinical trial information: NCT03088878.

TK216 for relapsed/refractory Ewing sarcoma: Interim phase 1/2 results

11500

Background: Ewing Sarcoma (ES) is a rare cancer of the young with very few treatment options in the relapsed/refractory (R/R) setting. Fusions of the EWS gene and one of five different ETS transcription factors are dominant drivers of ES. TK216 was designed to bind ETS proteins directly, disrupt protein-protein interactions, and inhibit transcription factor function. TK216 plus vincristine (VCR) exerted synergistic activity in non-clinical models . Here, we report updated interim results of the Phase 1/2 trial of TK216 ± vincristine in R/R ES. Methods: TK216 was administered by continuous IV infusion to adult and pediatric patients (pts) with R/R ES using a 3+3 design. Dosing duration of 7 days was later extended to 10 and 14 days. Dose limiting toxicity was evaluated during Cycle 1. VCR could be added after Cycle 2. The MTD for the 14-day infusion was 200 mg/m2/d, which was selected as the recommended Phase 2 dose (RP2D) for the Expansion cohort, with VCR started in Cycle 1. Results: Thirty-two R/R pts in 9 dose and schedule escalation cohorts, and 31 pts in the Phase 2 Expansion cohort were enrolled. Thirty-five pts were treated at the RP2D. Mean age was 30.6 years and 61% were males. Median prior treatment regimens for recurrent/metastatic ES were 3 (range 0-13). Median time from initial diagnosis of ES to study start was 3.5 years (range 0.3-18.1). Prior procedures included surgery (84%) and radiation (81%). At study entry, all pts had metastases with sites being bone only (13%), pleuropulmonary only (39%), and other metastatic (47%). As of the 20JAN2021 safety cutoff, the most common AEs observed in 62 treated pts, regardless of causality, included anemia (n = 34), neutropenia (n = 30) and fatigue (n = 25). Myelosuppression observed was transient, reversible, and responsive to growth factors. No deaths were attributed to TK216. As of the 06FEB2021 efficacy cut-off, 28/35 pts treated at the RP2D were evaluable for efficacy: Complete response (CR) 7.1%, stable disease (SD) 39.3%, progressive disease (PD) 53.6%, for an overall clinical benefit (CR+PR+SD) rate of 46.4%. SD median duration was 113 days (range 62-213). Three tumor responses were notable. One pt had regression of the target lesion after 2 cycles of TK216 alone, then after 6 cycles of TK216 + VCR therapy a residual non-target lesion was removed, for a surgical CR, without PD at 24 months on study. A second pt had a CR after 6 cycles of combination therapy, without PD at 18 months on study. After 4 cycles of TK216 + VCR therapy, a third pt had a PR of the target lesion, is receiving local therapy for PD of a non-target lesion and remains on study. Pts treated with the RP2D had a longer PFS than those in the dose escalation cohorts. Conclusions: TK216 plus VCR was well tolerated and showed encouraging early evidence of anti-tumor activity in this heavily pre-treated/ high tumor burden ES pt population. Clinical trial information: NCT02657005.

Clinical activity of cirmtuzumab, an anti-ROR1 antibody, in combination with ibrutinib: Interim results of a phase Ib/II study in mantle cell lymphoma (MCL) or chronic lymphocytic leukemia (CLL)

8036

Background: ROR1 is an onco-embryonic tyrosine kinase receptor that is re-expressed at high levels on many hematologic and solid cancers but not on normal adult tissues. ROR1 binds Wnt5a, resulting in increased tumor growth and survival, cancer cell stemness and epithelial mesenchymal transition. Cirmtuzumab (Cirm) is a humanized monoclonal antibody designed to inhibit the tumor promoting activity of ROR1. In this study, we examined the safety and efficacy of Cirm in combination with ibrutinib (Ibr) in MCL or CLL. Methods: As of Jan 29, 2020, 12 pts with relapsed refractory (RR) MCL were enrolled into Part 1 Dose Escalation (DE). All MCL pts had stage 3/ 4 at original diagnosis, 25% had bulky tumor at study entry, 58% had intermediate/high risk MIPI scores and the majority (83%) had ≥ 2 prior regimens. 34 pts with CLL [12 treatment naïve (TN) and 22 RR pts] enrolled into Part 1 DE (n = 18) or Part 2 Expansion (n = 16). At least 79% of CLL pts were high risk as determined by unmutated IGHV, 17p/p53 loss, and/or del 11q. DE pts received Cirm IV q2wks x 3-5 doses then q4wks plus Ibr (starting D28). Following DE, Cirm 600mg IV q2wks x3 then q4wks plus Ibr (420mg/day CLL or 560mg/day MCL) was chosen for Expansion. Results: Safety : only grade 1/ 2 AEs were reported as possibly related to Cirm alone, whereas the safety profile attributed to Ibr or Ibr / Cirm was similar to published data, with no new or unexpected events. Efficacy for MCL: 83% ORR, 33% (4) CR, 50% (6) PR, 17% (2) SD. CRs were achieved at a median of 3.6 mos in heavily pretreated pts, including 2 with bulky disease > 5cm. Prior therapy of the 4 CR pts: 2 pts failed R-Ibr (7-10 mos) and R-hyperCVAD, 1 pt, auto-SCT and allo-SCT, 1 pt, auto-SCT and CAR-T. Efficacy for CLL : 88% ORR (92% TN, 86% RR), 3% (1) CR, 85% (22) PR/ (7) PR-L, 12% (4) SD. In addition, 3 PR pts with CLL met criteria for “Clinical CR, bone marrow biopsy not performed”. The pt achieving a CR had RR disease with del 11q; this pt remains in remission > 6 mos after stopping all therapy. At a median follow-up of 9.9 mos, 100% of CLL pts are free of disease progression and > 82% remain on study. Conclusions: Cirm in combination with Ibr is a well-tolerated and active regimen for RR MCL and TN or RR CLL. In this evaluation of 46 pts, the ORR and PFS continue to improve with longer follow-up and additional pts, supporting continued investigation of this regimen in ROR1 expressing tumors. This study is ongoing and enrolling an Expansion arm for MCL pts and an open-label randomized Phase 2 in CLL pts comparing Ibr alone to Cirm /Ibr. Clinical trial information: NCT03088878 .

Phase 1/2 trial of cirmtuzumab and ibrutinib: Planned analysis of phase 1 CLL cohorts

7527

Background: Cirmtuzumab (C) is a humanized mAb that binds ROR1 and blocks Wnt5a from binding and activating ROR1 on CLL and mantle cell lymphoma (MCL); C does not bind normal adult tissues. A phase 1 trial of C showed excellent safety and inhibition of Wnt5a-ROR1 signaling. Ibrutinib (Ibr) does not inhibit the ROR1 pathway, and C+Ibr exert synergistic effects in CLL and MCL. The current clinical trial combines C+Ibr for patients (pts) with CLL and MCL. A planned analysis of the phase 1 CLL portion is presented. Methods: Eligible pts had CLL needing treatment according to iwCLL guidelines. C was given at 2, 4, 8, or 16 mg/kg q 2 wk for 8 wk, then q 28 d to 52 wk. Ibr 420 mg PO daily was started on d 28. Results: 3 pts were treated at each C dose level with age 57-86; 75% were previously treated (median 2); 3 pts had del(11q), 3 had trisomy 12, and 6 pts had unmutated IGVH genes. There were no discontinuations for toxicity and no dose limiting toxicities. Treatment with C alone and combined with Ibr was well-tolerated. One SAE occurred with C monotherapy (hospitalization for tonsillitis). Adverse events on C+Ibr were consistent with the known Ibr safety profile, with one grade 3 hyperkalemia and 1 atrial fibrillation event. All other AEs were grade 1 or 2. The overall response rate after 16-48 weeks of treatment was 67% with 1 confirmed complete response (CR) with no morphologic evidence of CLL in the marrow, 1 clinical CR, 6 partial responses (PR) and 4 stable disease. No patient had progressive disease. The typical redistributive lymphocytosis seen with Ibr was blunted, with only a 50% mean rise in ALC, rapidly returning to baseline. PRs were observed in all C dose levels. Conclusions: The combination of C+Ibr is well-tolerated and effective. CRs were observed in 2 cases, a result that would be highly unusual with Ibr monotherapy in CLL. Based on these findings, Cirm 600 mg was selected as the RP2D for the randomized phase 2 portion of this protocol, which will prospectively compare the complete response rates between C+Ibr and Ibr alone. Clinical trial information: NCT03420183.

A phase I, first-in-human, dose escalation study of intravenous TK216 in patients with relapsed or refractory Ewing sarcoma

TPS11626

Background: Ewing sarcoma (ES) is a rare cancer that affects children and young adults. Patients with recurrent/refractory ES have a poor prognosis (5-year survival 10-15%) with no improvement despite advances in cytotoxic and targeted therapies. Genomic rearrangements resulting in fusion proteins and over-expression of ets family transcription factors occur in 95% of ES. In particular, the EWS-FLI1 oncogenic fusion creates a constitutively active transcription factor that drives the malignant ES phenotype. Strategies to target the EWS-FLI1 fusion protein have been limited by lack of specificity. A promising approach is to target the interaction of the ets transcription factor with its critical protein partner, RNA helicase A (RHA). TK216 is a novel small-molecule that directly binds to EWS-FLI1 and inhibits its function by blocking binding to RHA. TK216 demonstrates potent anti-proliferative effects on ES cell lines and xenografts. Methods: We initiated a Phase 1, first-in-human, open-label, multi-center, dose-escalation/dose-expansion trial of TK216 in patients with recurrent/refractory ES who are ≥12 years of age (ClinicalTrials.gov: NCT02657005). TK216 is dosed based on body surface area and administered as a continuous intravenous infusion for 7 days followed by 14 days rest every 21 days. Treatment may continue in the absence of disease progression. One intrapatient dose escalation is allowed. Enrollment of 6 to 8 cohorts using a 3+3 dose-escalation design is anticipated. During dose expansion, a total of 18 patients with ES will be accrued at the recommended Phase 2 dose (RP2D). The primary objective of the study is to determine the maximum tolerated dose and RP2D of TK216. Secondary objectives are to assess the safety profile, pharmacokinetics, pharmacodynamics, and antitumor activity of TK216. Molecular assays will be performed to characterize EWS-FLI or EWS-ets abnormalities in archival tumor tissue. The overall response rate, duration of response, progression-free survival, and overall survival will be determined in the expansion cohort. Nine patients have been enrolled since June 2016. Accrual to cohorts 1, 2, and 3 completed and cohort 4 opened in January 2017. Clinical trial information: NCT02657005.

A phase I study of recombinant interferon-beta in patients with advanced malignant disease

To evaluate the safety, toxicity, and maximum tolerated dose (MTD) of IFN beta-1a (Rebif, Serono Laboratories, Inc.) in patients with malignant diseases unresponsive to standard therapies and to assess the pharmacodynamics and pharmacokinetics associated with IFN beta-1a administration, an open-label, single-center phase I study was designed. Thirty-four patients were enrolled and treated with IFN beta-1a. All had measurable solid neoplasms or evaluable hematological malignancies. All patients received a single i.v. bolus dose of IFN-beta-1a on day 1, followed 7 days later by daily s.c. injections for 28 consecutive days. Successive groups of three patients received increasingly higher doses (in geometric progression from 1.5 million international units (MIU)/m2 to 24 MIU/m2) until dose-limiting toxicities were noted. Pharmacokinetic and biological studies, including measurement of the activity of 2',5'-oligoadenylate synthetase (2',5'-OAS) in peripheral blood mononuclear cells and serum levels of soluble Tac (CD 25) and beta-2 microglobulin, were performed on patients who agreed to participate. i.v. and s.c. doses of IFN beta-1a up to 24 MIU/m2 were administered. The most frequent adverse events (AEs) were constitutional symptoms. Grade III AEs during i.v. dosing included fever, elevation of bilirubin, and infection unrelated to therapy. No grade IV events were seen. AEs noted during continuous s.c. therapy included fever, liver transaminase increase, albuminuria, fatigue, nausea, myalgia, and rigors. Dose-limiting toxicities were encountered during s.c. dosing at the 24-MIU/m2 and 18-MIU/m2 dose levels and included gastrointestinal toxicity, elevations of aspartate aminotransferase and alanine aminotransferase, and albuminuria. The s.c. MTD was determined to be 12 MIU/m2, although there was great variability in the individual patient's ability to tolerate IFN beta-1a. 2',5'-OAS activity, thought to be indicative of IFN activity, increased within hours after i.v. and s.c. dosing, with the level remaining persistently elevated during the s.c. daily injections. The highest peak level was attained in the 6-MIU/m2 group. There was no evidence that the increase in 2',5'-OAS activity decayed with repetitive dosing, nor was there evidence of accumulation in this pharmacodynamic marker. Serum beta-2-microglobulin levels showed a modest time- and dose-dependent increase after s.c. administration of IFN beta-1a, with the largest increase seen at the 24-MIU/m2 dose level. There were no clear dose-dependent responses noted in soluble Tac serum levels. IFN beta-1a was well-tolerated when administered by a single i.v. bolus injection at doses up to and including 24 MIU/m2. Daily s.c. injections for at least 28 days were well-tolerated at doses up to and including 12 MIU/m2, with some patients tolerating doses twice as high as this. The MTD for the i.v. route could not be clearly determined according to the guidelines of the protocol. However, i.v. bolus doses up to 24 MIU/m2 were relatively well-tolerated. For the s.c. route, the MTD was determined to be 12 MIU/m2, but there was great interpatient variability, with some patients able to tolerate higher doses.

Recombinant human growth hormone in patients with HIV-associated wasting. A randomized, placebo-controlled trial. Serostim Study Group

BACKGROUND

Body wasting, particularly loss of body cell mass, is an increasingly prevalent acquired immunodeficiency syndrome (AIDS)-defining condition and is an independent risk factor for death in patients infected with the human immunodeficiency virus (HIV). Treatment with growth hormone for 7 days resulted in weight gain and nitrogen retention, but the long-term effects of this treatment in patients with HIV-associated wasting are not known.

OBJECTIVE

To evaluate the long-term effect of treatment with growth hormone on weight, body composition, functional performance, and quality of life in patients with HIV-associated wasting.

DESIGN

Randomized, double-blind, placebo-controlled, multicenter trial.

SETTING

Outpatient university and community-based patient care facilities.

PATIENTS

178 HIV-infected patients with documented unintentional weight loss of at least 10% or weight less than 90% of the lower limit of ideal body weight.

INTERVENTION

Patients were randomly assigned to receive either recombinant human growth hormone, 0.1 mg/kg of body weight per day (average dosage, 6 mg/d) (n = 90) or placebo (n = 88) for 12 weeks.

MEASUREMENTS

Weight; body fat, lean body mass, and bone mineral content (measured by dual-energy x-ray absorptiometry); total body water (by deuterium oxide dilution); extracellular water (by sodium bromide dilution); work output (by treadmill exercise); quality of life; and safety of treatment.

RESULTS

Treatment with growth hormone resulted in a sustained and statistically significant increase in weight (mean increase +/- SD, 1.6 +/- 3.7 kg [P < 0.001]) and lean body mass (3.0 +/- 3.0 kg [P < 0.001]), accompanied by a decrease in body fat (-1.7 +/- 1.7 kg [P < 0.001]). In contrast, in patients receiving placebo, weight (increase, 0.1 +/- 3.1 kg), lean body mass (decrease, 0.1 +/- 2.0 kg), and body fat (decrease, 0.3 +/- 2.2 kg) did not change significantly from baseline. Differences between groups at week 12 were statistically significant (P = 0.011 for body weight and P < 0.001 for lean body mass and body fat). A greater increase in treadmill work output was noted in the group receiving growth hormone (increase, 99 +/- 293 kg. m/min) compared with the group receiving placebo (increase, 20 +/- 233 kg.m/min)(P = 0.039). Health status (quality of life) scores did not differ between groups at baseline or after treatment. Days of disability and use of medical resources were the same for both groups. Treatment was was well tolerated; no significant differences were seen between groups in clinical events, progression of AIDS, CD4+ or CD8+ cell counts, or viral burden.

CONCLUSION

Treatment with growth hormone increases body weight, lean body mass, and treadmill work output and appears to be a safe and potentially effective therapy in patients with HIV-associated wasting.

Platelet transfusion and alternatives to transfusion in patients with malignancy

Platelet transfusions have long had an important role in the treatment of patients with thrombocytopenia due to disease or myelotoxic treatment or in patients with reduced platelet function. However, platelet transfusions are associated with numerous risks, both immunologic (e.g., transfusion reactions, alloimmunization, immunosuppression) and infectious (e.g., viral, bacterial). In addition, several laboratory and clinical factors can influence post-transfusion platelet recovery. Recent technological advances have introduced the potential for using alternatives to platelet transfusions, such as cytokines or platelet substitutes, which may avoid the risks of transfusion. Platelet development from megakaryocytes is a process that is highly regulated by cytokines and animal research suggests that selected cytokines involved in this process may be useful in the treatment of thrombocytopenia. Newer developments, including the utilization of recombinant cytokines with relatively selective stimulation of platelet production (e.g., interleukin 6 [IL-6]) and the recent discovery of a megakaryocyte colony stimulating factor (thrombopoietin), represent major therapeutic opportunities in the treatment of thrombocytopenia. Platelet substitutes, e.g., thromboerythrocytes, also show promise in the management of platelet deficiencies.

Adjuvant chemotherapy of breast cancer

Many women will not be cured of breast cancer by even the best early detection and surgical techniques because of micrometastases present at diagnosis. Adjuvant therapy has extended the disease-free interval for most patients and lengthens overall survival for many. Combination chemotherapy has become the standard form of adjuvant treatment for premenopausal women with breast cancer and positive lymph nodes after primary therapy. With minimal toxicity, disease-free and overall survival are improved. Results are less impressive or less clear-cut for postmenopausal women or any woman with negative lymph nodes. Long-term toxicities of adjuvant chemotherapy may include second malignancies and cardiac dysfunction. Although these complications probably are rare, they must be considered seriously when weighing chemotherapy for patients in whom its benefits may be slight. Innovations likely to become standard in adjuvant therapy decision making include risk assessment with new prognostic indicators (growth fraction, oncogene expression) and investigation of dose intensification using bone marrow growth factors and autologous stem-cell support.

Comprehensive management of disseminated breast cancer

The management of patients with metastatic breast cancer is best achieved by the judicious use of local and systemic measures that palliate symptoms and improve overall quality of life. When two treatment approaches are known to be equally efficacious, the less toxic should be used. When disease is limited to one or two sites and the patient has an indolent form of the disease, the patient's symptoms are often best palliated with the use of surgery or radiotherapy alone. When multiple sites of disease are evident or the disease is progressing more rapidly, systemic therapy is preferred, and local therapies should be added when the patient is clearly refractory to systemic therapy or when the disease site is unlikely to be adequately palliated with systemic therapy. The use of any of these therapies, including chemotherapy, has a relatively small effect on the median survival of patients with metastatic breast cancer. However, improvements in quality of life are usually greatest with regimens inducing the highest response rates, even when these regimens are associated with greater toxicity. The characteristics of patients likely to respond to endocrine therapy are well defined; in these patients endocrine therapy should be used as the first form of systemic therapy. Among endocrine therapies, the least toxic is used first. The selection of patients for chemotherapy is largely a process of exclusion. When chemotherapy is used, there are a number of different strategies for sequencing chemotherapy that appear to be equally efficacious. In general, patients should be treated with standard doses of drug combinations for a period in excess of 3 months. When used inappropriately, especially in asymptomatic patients, these therapies may actually compromise the patient's quality of life. The use of surgery, radiation therapy, and systemic therapy should be integrated with various types of psychosupport services, especially peer support groups. Patients who want to try new forms of therapy should do so early in the course of the disease when these therapies are most likely to be effective and the patient has the least to lose if the therapy proves ineffective. This is especially true because the use of the most effective regimens at a time when the patient is asymptomatic may mean that the patient is resistant to most or all therapies of proven value when most in need of palliation.

Adjuvant systemic therapy for patients with node-negative tumors

Early adjuvant therapy studies, especially adjuvant chemotherapy studies, were performed almost exclusively on patients with histologically involved axillary lymph nodes ("node-positive" patients). These therapies were restricted to this group of patients because the toxicities of adjuvant therapy were believed too great to justify its use in patients with a very good prognosis until its benefits were fully established. However, after it was demonstrated that adjuvant therapy can significantly prolong the disease-free survival of almost all groups of node-positive patients and the overall survival of some patient subsets, adjuvant therapy trials specifically designed for patients without histologically involved lymph nodes ("node-negative" patients) were initiated. Results from some of the largest of these second generation trials were recently published, and the early results from these studies have generated new questions. For example, will the mature results from these studies be nearly identical to the results seen in node-positive patients, or will node-negative patients derive greater benefits from adjuvant therapy? Is it possible that adjuvant therapy will "cure" node-negative patients but not node-positive patients? (Cure is defined here as an effect of therapy that returns a patient to the life expectancy she might have had if she had never been diagnosed with breast cancer). Is it possible that the added years of life from adjuvant therapy or that the number of node-negative patients who benefit are so small that these benefits will be outweighed by delayed toxicities that appear in patients who might have been cured even without adjuvant therapy? At present the available data to answer these questions definitely are either contradictory or nonexistent.

FcR-mediated crosslinking of Ta1 (CDw26) induces human T lymphocyte activation

Ta1 (CDw26) is a 105-kDa glycoprotein of unknown function whose expression on human T lymphocytes is strongly correlated with activation and proliferation. The subset of peripheral blood T cells expressing Ta1 includes the principal responsive population to proliferative stimulation by recall antigens as well as monoclonal antibodies directed to the CD3/T cell receptor complex and the CD2 (T11) molecule. We now show that the Ta1 molecule is itself an alternate mediator of human T lymphocyte activation. T cell clones were induced to proliferate and exert their cytolytic effector function by anti-Ta1 monoclonal antibodies in the presence of Fc-receptor-positive accessory or target cells. Resting T cells from peripheral blood were also activated to proliferate by anti-Ta1, but only if both Fc-receptor-positive accessory cells and exogenous IL-2 were present. Anti-Ta1 antibodies induced increased expression of IL-2 receptors on purified T cells under these conditions. Activation via Ta1 was shown to be functionally interconnected to CD3/T cell receptor activation mechanisms, because modulation of the CD3/T cell receptor complex inhibited anti-Ta1-mediated cytolysis without affecting Ta1 surface expression. While demonstrating that the CDw26 antigen-mediated pathway of activation is not dependent on one unique epitope, our results suggest that the Ta1 glycoprotein can mediate T cell activation directly, suggesting that it may be associated with an important cellular component of the human T cell regulatory network.

Sheep erythrocyte rosetting induces multiple alterations in T lymphocyte function: inhibition of T cell receptor activity and stimulation of T11/CD2

When T lymphocytes from human blood or lymphoid organs are prepared by the sheep red blood cell (SRBC) rosetting procedure, glycoproteins of the SRBC membrane interact intimately with the CD2 (T11) molecule on the T cell surface. We now show that rosette formation has measurable short- and long-term effects upon the T cells. First, for a period of 24-48 hr after rosetting, the signal transducing and activation functions of the T3/Ti T cell antigen receptor complex is paralyzed for anti-T3-induced calcium mobilization, with a concomitant decrease in proliferative response to mitogens or stimulatory anti-T3 antibodies. Calcium mobilization through the alternate pathway of T cell activation, the T11/CD2 SRBC receptor, was also inhibited by rosetting. Second, rosetting appears to confer a partial stimulatory signal through the T11/CD2 pathway. Thus, 72 hr or more after rosetting, there was increased expression of the T11(3) activation epitope, and rosetted T cells were stimulated to proliferate in the presence of anti-T11(3) antibodies alone. These results provide further details on the effects of SRBC-T cell interactions, with important methodological implications. Moreover, they suggest a hitherto unrecognized down-regulatory effect of engaging the CD2 molecule, and provide further evidence that the T cell receptor is functionally interconnected to the CD2 activation pathway.

Regulation of T cell clone function via CD4 and CD8 molecules. Anti-CD4 can mediate two distinct inhibitory activities

The functional effects resulting from CD4 and CD8 perturbation were analyzed by using a CD4+CD8+ clone and anti-CD4 and anti-CD8 monoclonal antibodies. Perturbation of CD8, but not CD4, by soluble antibody resulted in the inhibition of CD3-T cell receptor (CD3-Ti) triggering as determined by flow cytometric measurements of intracellular free Ca2+ concentrations. In addition, the CD3-T cell receptor-mediated cytotoxic function of the CD4+CD8+ clone was inhibited by anti-CD8, but not by anti-CD4. These results suggest that CD8, but not CD4, was functionally associated with CD3-Ti on the CD4+CD8+ clone. Although CD4 perturbation did not affect CD3-Ti-mediated activities, it resulted in the inhibition of the interleukin 2-dependent proliferation of this clone. Perturbation of CD8 did not affect the interleukin 2 dependent proliferation of the CD4+CD8+ clone. On the other hand, CD4 molecules of another CD4+CD8- clone unlike those of the CD4+CD8+ clone, were clearly linked to T cell receptor function. These results indicate that CD4 perturbation can result in two distinct regulatory activities; one involves the regulation of CD3-T cell receptor function, whereas the other is not directly associated with CD3-T cell antigen receptor function. The data are also consistent with the notion that CD4 and CD8 do not merely function as recognition and adhesion elements for accessory cell major histocompatibility complex molecules, but have a direct role in the regulation of T cell activation.

Regulation of T cell clone function via CD4 and CD8 molecules. Anti-CD4 can mediate two distinct inhibitory activities

The functional effects resulting from CD4 and CD8 perturbation were analyzed by using a CD4+CD8+ clone and anti-CD4 and anti-CD8 monoclonal antibodies. Perturbation of CD8, but not CD4, by soluble antibody resulted in the inhibition of CD3-T cell receptor (CD3-Ti) triggering as determined by flow cytometric measurements of intracellular free Ca2+ concentrations. In addition, the CD3-T cell receptor-mediated cytotoxic function of the CD4+CD8+ clone was inhibited by anti-CD8, but not by anti-CD4. These results suggest that CD8, but not CD4, was functionally associated with CD3-Ti on the CD4+CD8+ clone. Although CD4 perturbation did not affect CD3-Ti-mediated activities, it resulted in the inhibition of the interleukin 2-dependent proliferation of this clone. Perturbation of CD8 did not affect the interleukin 2 dependent proliferation of the CD4+CD8+ clone. On the other hand, CD4 molecules of another CD4+CD8- clone unlike those of the CD4+CD8+ clone, were clearly linked to T cell receptor function. These results indicate that CD4 perturbation can result in two distinct regulatory activities; one involves the regulation of CD3-T cell receptor function, whereas the other is not directly associated with CD3-T cell antigen receptor function. The data are also consistent with the notion that CD4 and CD8 do not merely function as recognition and adhesion elements for accessory cell major histocompatibility complex molecules, but have a direct role in the regulation of T cell activation.

The T11 (CD2) molecule is functionally linked to the T3/Ti T cell receptor in the majority of T cells

Most mature human T lymphocytes express both the multichain T3 (CD3)/Ti T cell receptor for antigen (TCR), and the biochemically distinct 55-kDa T11 (CD2) glycoprotein. Stimulating the T11 molecule causes profound T cell proliferation and functional activation in vitro, but the relationship of T11-mediated activation to antigenic stimulation of T lymphocytes in vivo remains unknown. We now present evidence that T11 function is directly linked to TCR components in T3/Ti+ T11+ human T cells. First, we found that stimulating peripheral blood T cells with the mitogenic combination of anti-T11(2) cells with the mitogenic combination of anti-T11(2) plus anti-T11(3) monoclonal antibodies caused the phosphorylation of TCR T3 chains. The predominance of T3-gamma-phosphorylation that occurred in anti-T11(2) plus anti-T11(3)-treated T cells is similar to the pattern previously observed in antigen-stimulated T cell clones. Second, T11 function depended upon concurrent cell-surface expression of the TCR. Thus, when peripheral blood T cells were deprived of cell surface T3/Ti by anti-T3 modulation, anti-T11(2) plus anti-T11(3)-induced mitogenesis and transmembrane signal generation in the form of calcium mobilization were inhibited. The mechanism of TCR-T11 interdependence was investigated in a series of TCR-deficient variants of a T cell lymphoblastoid cell line. T3/Ti negative variants expressed cell surface T11, but anti-T11(2) plus anti-T11(3) failed to cause detectable calcium mobilization. The TCR-deficient variants also failed to express T11(3) activation epitopes after incubation with anti-T11(2) antibodies, suggesting that T11(3) expression is an essential and TCR-dependent intermediate in the T11 activation mechanism in these cells. Taken together, our results suggest that T11 function depends upon cell-surface expression of TCR in many T3/Ti+ T11+ T lymphocytes, and T11-mediated activation is intimately interconnected with TCR activation mechanisms. A model in which stimulating signals delivered via T11 may be a part of antigenic activation of T lymphocytes is presented.

The T11 (CD2) molecule is functionally linked to the T3/Ti T cell receptor in the majority of T cells

Most mature human T lymphocytes express both the multichain T3 (CD3)/Ti T cell receptor for antigen (TCR), and the biochemically distinct 55-kDa T11 (CD2) glycoprotein. Stimulating the T11 molecule causes profound T cell proliferation and functional activation in vitro, but the relationship of T11-mediated activation to antigenic stimulation of T lymphocytes in vivo remains unknown. We now present evidence that T11 function is directly linked to TCR components in T3/Ti+ T11+ human T cells. First, we found that stimulating peripheral blood T cells with the mitogenic combination of anti-T11(2) cells with the mitogenic combination of anti-T11(2) plus anti-T11(3) monoclonal antibodies caused the phosphorylation of TCR T3 chains. The predominance of T3-gamma-phosphorylation that occurred in anti-T11(2) plus anti-T11(3)-treated T cells is similar to the pattern previously observed in antigen-stimulated T cell clones. Second, T11 function depended upon concurrent cell-surface expression of the TCR. Thus, when peripheral blood T cells were deprived of cell surface T3/Ti by anti-T3 modulation, anti-T11(2) plus anti-T11(3)-induced mitogenesis and transmembrane signal generation in the form of calcium mobilization were inhibited. The mechanism of TCR-T11 interdependence was investigated in a series of TCR-deficient variants of a T cell lymphoblastoid cell line. T3/Ti negative variants expressed cell surface T11, but anti-T11(2) plus anti-T11(3) failed to cause detectable calcium mobilization. The TCR-deficient variants also failed to express T11(3) activation epitopes after incubation with anti-T11(2) antibodies, suggesting that T11(3) expression is an essential and TCR-dependent intermediate in the T11 activation mechanism in these cells. Taken together, our results suggest that T11 function depends upon cell-surface expression of TCR in many T3/Ti+ T11+ T lymphocytes, and T11-mediated activation is intimately interconnected with TCR activation mechanisms. A model in which stimulating signals delivered via T11 may be a part of antigenic activation of T lymphocytes is presented.

Growth inhibition of human T cells by antibodies recognizing the T cell antigen receptor complex

Monoclonal antibodies that bind to the T cell MHC-antigen recognition complex (anti-T3 or anti-Ti) are known to either mimic ligand binding and activate T cells or block ligand binding, leading to an inhibition of T cell activation. In the present experiments, we demonstrate a direct inhibitory effect on the growth of human T cells by anti-T3 or anti-Ti antibodies. The proliferation of human peripheral blood T cells preactivated by exposure to PHA was inhibited in a specific manner by anti-T3. Colony formation in soft agar by REX cells, a leukemic cell line of early T cell phenotype, was completely inhibited by anti-T3 or anti-Ti antibodies, whereas isotype-matched antibodies to a variety of other T cell markers had no effect. Growth of REX cells in suspension culture was not affected by anti-T3 or anti-Ti. A cell line, T3.N1, was established from an agar colony of anti-T3-resistant REX cells. T3.N1 was phenotypically identical to REX except for failure to express any detectable T3 or Ti surface antigen. T3.N1 colony formation in soft agar was not inhibited by anti-T3 or anti-Ti. There was no rise in [Ca2+]i of T3.N1 cells after anti-T3 or anti-Ti exposure. These results indicate that in addition to the well-known positive regulatory effects of ligand binding to the T3/Ti complex, T3/Ti binding can also result in a down-regulatory signal for human T cell growth.

Growth inhibition of human T cells by antibodies recognizing the T cell antigen receptor complex

Monoclonal antibodies that bind to the T cell MHC-antigen recognition complex (anti-T3 or anti-Ti) are known to either mimic ligand binding and activate T cells or block ligand binding, leading to an inhibition of T cell activation. In the present experiments, we demonstrate a direct inhibitory effect on the growth of human T cells by anti-T3 or anti-Ti antibodies. The proliferation of human peripheral blood T cells preactivated by exposure to PHA was inhibited in a specific manner by anti-T3. Colony formation in soft agar by REX cells, a leukemic cell line of early T cell phenotype, was completely inhibited by anti-T3 or anti-Ti antibodies, whereas isotype-matched antibodies to a variety of other T cell markers had no effect. Growth of REX cells in suspension culture was not affected by anti-T3 or anti-Ti. A cell line, T3.N1, was established from an agar colony of anti-T3-resistant REX cells. T3.N1 was phenotypically identical to REX except for failure to express any detectable T3 or Ti surface antigen. T3.N1 colony formation in soft agar was not inhibited by anti-T3 or anti-Ti. There was no rise in [Ca2+]i of T3.N1 cells after anti-T3 or anti-Ti exposure. These results indicate that in addition to the well-known positive regulatory effects of ligand binding to the T3/Ti complex, T3/Ti binding can also result in a down-regulatory signal for human T cell growth.