Lenvatinib plus pembrolizumab versus lenvatinib plus placebo for advanced hepatocellular carcinoma (LEAP-002): a randomised, double-blind, phase 3 trial

BACKGROUND

Systemic therapies have improved the management of hepatocellular carcinoma, but there is still a need to further enhance overall survival in first-line advanced stages. This study aimed to evaluate the addition of pembrolizumab to lenvatinib versus lenvatinib plus placebo in the first-line setting for unresectable hepatocellular carcinoma.

METHODS

In this global, randomised, double-blind, phase 3 study (LEAP-002), patients aged 18 years or older with unresectable hepatocellular carcinoma, Child Pugh class A liver disease, an Eastern Cooperative Oncology Group performance status of 0 or 1, and no previous systemic treatment were enrolled at 172 global sites. Patients were randomly assigned (1:1) with a central interactive voice-response system (block size of 4) to receive lenvatinib (bodyweight <60 kg, 8 mg/day; bodyweight ≥60 kg, 12 mg/day) plus pembrolizumab (200 mg every 3 weeks) or lenvatinib plus placebo. Randomisation was stratified by geographical region, macrovascular portal vein invasion or extrahepatic spread or both, α-fetoprotein concentration, and Eastern Cooperative Oncology Group performance status. Dual primary endpoints were overall survival (superiority threshold at final overall survival analysis, one-sided p=0·019; final analysis to occur after 532 events) and progression-free survival (superiority threshold one-sided p=0·002; final analysis to occur after 571 events) in the intention-to-treat population. Results from the final analysis are reported. This study is registered with ClinicalTrials.gov, NCT03713593, and is active but not recruiting.

FINDINGS

Between Jan 17, 2019, and April 28, 2020, of 1309 patients assessed, 794 were randomly assigned to lenvatinib plus pembrolizumab (n=395) or lenvatinib plus placebo (n=399). Median age was 66·0 years (IQR 57·0-72·0), 644 (81%) of 794 were male, 150 (19%) were female, 345 (43%) were Asian, 345 (43%) were White, 22 (3%) were multiple races, 21 (3%) were American Indian or Alaska Native, 21 (3%) were Native Hawaiian or other Pacific Islander, 13 (2%) were Black or African American, and 46 (6%) did not have available race data. Median follow up as of data cutoff for the final analysis (June 21, 2022) was 32·1 months (IQR 29·4-35·3). Median overall survival was 21·2 months (95% CI 19·0-23·6; 252 [64%] of 395 died) with lenvatinib plus pembrolizumab versus 19·0 months (17·2-21·7; 282 [71%] of 399 died) with lenvatinib plus placebo (hazard ratio [HR] 0·84; 95% CI 0·71-1·00; stratified log-rank p=0·023). As of data cutoff for the progression-free survival final analysis (April 5, 2021), median progression-free survival was 8·2 months (95% CI 6·4-8·4; 270 events occurred [42 deaths; 228 progressions]) with lenvatinib plus pembrolizumab versus 8·0 months (6·3-8·2; 301 events occurred [36 deaths; 265 progressions]) with lenvatinib plus placebo (HR 0·87; 95% CI 0·73-1·02; stratified log-rank p=0·047). The most common treatment-related grade 3-4 adverse events were hypertension (69 [17%] of 395 patients in the lenvatinib plus pembrolizumab group vs 68 [17%] of 395 patients) in the lenvatinib plus placebo group), increased aspartate aminotransferase (27 [7%] vs 17 [4%]), and diarrhoea (25 [6%] vs 15 [4%]). Treatment-related deaths occurred in four (1%) patients in the lenvatinib plus pembrolizumab group (due to gastrointestinal haemorrhage and hepatorenal syndrome [n=1 each] and hepatic encephalopathy [n=2]) and in three (1%) patients in the lenvatinib plus placebo group (due to gastrointestinal haemorrhage, hepatorenal syndrome, and cerebrovascular accident [n=1 each]).

INTERPRETATION

In earlier studies, the addition of pembrolizumab to lenvatinib as first-line therapy for advanced hepatocellular carcinoma has shown promising clinical activity; however, lenvatinib plus pembrolizumab did not meet prespecified significance for improved overall survival and progression-free survival versus lenvatinib plus placebo. Our findings do not support a change in clinical practice.

FUNDING

Eisai US, and Merck Sharp & Dohme, a subsidiary of Merck.

Health-related quality of life (HRQoL) impact of lenvatinib (len) plus pembrolizumab (pembro) versus len plus placebo (pbo) as first-line (1L) therapy for advanced hepatocellular carcinoma (aHCC): Phase 3 LEAP-002 study

506

Background: In LEAP-002 (NCT03713593), len + pembro achieved a median OS of 21.2 mo vs 19.0 mo with len + pbo with manageable safety in both arms in 1L aHCC, although the significance thresholds for OS and PFS were not met. We present here the results of prespecified exploratory patient (pt)-reported outcomes (PROs). Methods: 794 pts were randomized. PROs were assessed by EORTC QLQ-C30, EuroQol-5D5L (EQ5D-5L), and EORTC QLQ-HCC18 questionnaires. Analysis population for HRQoL endpoints included pts who received ≥1 dose of study Tx and completed ≥1 HRQoL assessment. Least squares mean (LSM) score changes from baseline (BL) to wk 27 were compared using a constrained longitudinal data analysis model (covariates: Tx, time, Tx by time interaction, and stratification factors). Kaplan-Meier method was used to estimate time to deterioration (TTD, time to 1st onset of ≥10 [out of 100] deterioration from BL in a given scale or subscale/confirmed by a 2nd adjacent ≥10 deterioration from BL) for EORTC QLQ-C30 global health status (GHS)/QoL, physical functioning (PF), and EORTC QLQ-HCC18 abdominal swelling, pain and fatigue, as reported by pts. Stratified Cox proportional hazards model was used to assess the magnitude of the Tx difference (HR) between arms in TTD. Results: Compliance with PRO assessments was >91% from BL until wk 27 in both arms. From BL to wk 27, LSM changes in GHS/QoL, PF, role functioning (RF), QLQ-HCC18 functional/domain scores and EQ5D-5L VAS were generally similar between the two arms (Table). Treatment with len + pembro delayed deterioration of patient-reported quality of life vs len + pbo (median TTD, 11.5 vs 4.3 mo; HR, 0.80; 95% CI, 0.65-0.98). LSM score difference (95% CI) was 0.5 (-2.5, 3.4) for GHS/QoL, -1.7 (-4.5, 1.1) for PF, -1.0 (-4.9, 2.9) for RF, 1.0 (-2.2, 4.3) for abdominal swelling, 2.0 (-1.2, 5.2) for fatigue, 2.0 (-1.0, 5.0) for pain, and 0.6 (-2.0, 3.2) for EQ5D-5L VAS. Median TTD in QLQ-C30 PF (5.7 vs 9.1 mo; HR, 1.14; 95% CI, 0.93-1.41) and QLQ-HCC18 abdominal swelling (NR vs NR; HR, 1.19; 95% CI, 0.89-1.60) /fatigue (2.9 vs 2.8 mo; HR, 0.98; 95% CI, 0.81-1.19)/pain (9.6 vs 7.9 mo; HR, 0.93; 95% CI, 0.75-1.16) was similar between the arms. Conclusions: Len + pembro generally preserved HRQoL vs len + pbo in 1L for aHCC. Combined with efficacy and safety results from LEAP-002, these findings support continued development of len + pembro in HCC. Clinical trial information: NCT03713593 . [Table: see text]

Randomized Phase 3 LEAP-012 Study: Transarterial Chemoembolization With or Without Lenvatinib Plus Pembrolizumab for Intermediate-Stage Hepatocellular Carcinoma Not Amenable to Curative Treatment

PURPOSE

Transarterial chemoembolization (TACE) is the standard of care for patients with intermediate-stage hepatocellular carcinoma (HCC). Lenvatinib, a multikinase inhibitor, and pembrolizumab, a PD-1 inhibitor, have shown efficacy and tolerability in patients with HCC, and adding this combination to TACE may enhance clinical benefit.

PROTOCOL

LEAP-012 is a prospective, double-blind randomized phase 3 study. Adults with confirmed HCC localized to the liver without portal vein thrombosis and not amenable to curative treatment, ≥ 1 measurable tumor per Response Evaluation Criteria in Solid Tumors 1.1 (RECIST 1.1), Eastern Cooperative Oncology Group performance status 0 or 1, Child-Pugh class A and no previous systemic treatment for HCC are eligible. Patients will be randomly assigned to lenvatinib once daily plus pembrolizumab every 6 weeks plus TACE or placebos plus TACE. Dual primary endpoints are overall survival and progression-free survival per RECIST 1.1 by blinded independent central review (BICR). Secondary endpoints are progression-free survival, objective response rate, disease control rate, duration of response and time to progression per modified RECIST by BICR; objective response rate, disease control rate, duration of response and time to progression per RECIST 1.1 by BICR; and safety.

STATISTICS

The planned sample size, 950 patients, was calculated to permit accumulation of sufficient overall survival events in 5 years to achieve 90% power for the overall survival primary endpoint.

DISCUSSION

LEAP-012 will evaluate the clinical benefit of adding lenvatinib plus pembrolizumab to TACE in patients with intermediate-stage HCC not amenable to curative treatment.

CLINICALTRIALS

gov NCT04246177.

LEAP-012 trial in progress: Transarterial chemoembolization (TACE) with or without lenvatinib plus pembrolizumab for intermediate-stage hepatocellular carcinoma (HCC)

TPS494

Background: Limited treatment options are available for patients with intermediate HCC. Lenvatinib, a potent multikinase inhibitor, and pembrolizumab, a PD-1 inhibitor, are approved first- and second-line therapies for advanced HCC, respectively. The LEAP-012 study (NCT04246177) is investigating lenvatinib plus pembrolizumab in combination with TACE versus placebo plus TACE in patients with intermediate-stage HCC. Methods: LEAP-012 is a randomized, double-blind, phase 3 study. Adults with confirmed HCC localized to the liver without portal vein thrombosis and not amenable to curative treatment, ≥1 measurable lesion per RECIST v1.1, Eastern Cooperative Oncology Group performance status of 0 or 1, and no previous systemic treatment for HCC are eligible. Patients will be randomly assigned to receive lenvatinib 8 mg (body weight < 60 kg) or 12 mg (body weight ≥60 kg) orally once daily plus pembrolizumab 400 mg intravenously (IV) every 6 weeks (Q6W) plus TACE or placebo orally once daily plus placebo IV Q6W plus TACE. Response will be assessed by imaging every 9 weeks; safety will be assessed throughout the study and up to 90 days after the end of treatment. Dual primary end points are overall survival and progression-free survival (PFS) per RECIST v1.1 by blinded independent central review (BICR). Secondary end points are PFS, objective response rate (ORR), disease control rate (DCR), duration of response (DOR), and time to progression (TTP) per modified RECIST by BICR; ORR, DCR, DOR, and TTP per RECIST v1.1 by BICR; and safety. Exploratory end points are PFS, ORR, DCR, DOR, TTP, and time from randomization to second/subsequent disease progression after initiation of new anticancer therapy or death from any cause, whichever occurs first, per RECIST v1.1 by investigator review, identification of molecular biomarkers, and health-related quality of life. Recruitment began in April 2020, and the planned sample size is 950 patients. The results of the LEAP-012 study will show the clinical benefit of adding lenvatinib plus pembrolizumab to the current standard of care TACE for patients with intermediate-stage HCC not amenable to curative treatment. Clinical trial information: NCT04246177.

Exploratory circulating biomarker analyses: lenvatinib + pembrolizumab (L + P) in a phase 1b trial in unresectable hepatocellular carcinoma (uHCC)

4084

Background: In a phase 1b trial (NCT03006926), L + P had promising antitumor activity as first-line (1L) therapy in uHCC. We present exploratory biomarker analyses of circulating angiogenic factors and cytokines/chemokines related to the mechanism of action of L + P (ie, pharmacodynamic [PD] biomarkers), as well as biomarker correlations with clinical outcomes in patients (pts) with uHCC, from this trial. Methods: Pts received lenvatinib 12 mg/d (bodyweight [BW] >60 kg) or 8 mg/d (BW < 60 kg) PO + pembrolizumab 200 mg IV Q3W. Tumors were assessed using mRECIST or RECIST v1.1 per independent imaging review. Peripheral blood samples were collected before administration of study drug at baseline, cycle (C) 2, day (D) 1, C3D1, C4D1, and off-treatment. 43 Biomarkers were assayed in serum from 100 1L uHCC pts (excluding 4 pts from the dose-limiting toxicity part of the trial with prior sorafenib). Of these 43, 31 biomarkers (for which ≤20% of samples had measurements above/below the quantification limit of the assay) were included in the analyses. Changes in biomarker levels from baseline were evaluated via 1-sample Wilcoxon signed-rank test. Associations were explored between changes in biomarker levels and maximum tumor shrinkage (MTS) via the Spearman’s rank correlation test, objective response (OR; complete response + partial response) via the Wilcoxon rank sum test, and PFS via Cox regression analysis and log rank test. Data cutoff date for clinical endpoints was 7 August 2020. Results: Levels of PD biomarkers related to angiogenic signaling (VEGF increase/ANG2 decrease), FGF signaling (increase in FGF23/FGF19), and IFNγ signaling (increase in IFNγ, CXCL9/10/11) were changed significantly (adjusted P< 0.05) with L + P (C2D1–C4D1; except for FGF19 at C3D1). Significant decreases of TIMP1 and increases of MCP1 were observed at C4D1 during treatment; these were associated with greater MTS. Greater decreases in TIMP1 and greater increases in MCP1 were observed in pts with OR vs others. Changes in levels of the PD biomarkers ANG2, IL10, and VEGFR2 were found to be associated with PFS by dichotomized analysis. With tertile 2 cutoff, median PFS for pts in the group with greater decreases of ANG2 was 13.9 months vs 9.6 months for pts in the group with lesser decreases of ANG2 (unadjusted P= 0.002; HR 2.65, 95% CI 1.39–5.08). Conclusions: These are the first exploratory biomarker analyses for the single-arm study of L + P in pts with uHCC. Changes in serum biomarkers associated with angiogenic-, FGF-, and IFNγ-signaling pathways indicated target engagement of L + P. Decreases in TIMP1 and increases in MCP1 were associated with MTS and OR. Associations were found between longer PFS and a greater decrease in levels of ANG2. Angiogenesis inhibition and modulation of cancer immune response were observed with L + P. Further validation from independent studies is warranted. Clinical trial information: NCT03006926.

Phase Ib Study of Lenvatinib Plus Pembrolizumab in Patients With Unresectable Hepatocellular Carcinoma

PURPOSE

The immunomodulatory effect of lenvatinib (a multikinase inhibitor) on tumor microenvironments may contribute to antitumor activity when combined with programmed death receptor-1 (PD-1) signaling inhibitors in hepatocellular carcinoma (HCC). We report results from a phase Ib study of lenvatinib plus pembrolizumab (an anti-PD-1 antibody) in unresectable HCC (uHCC).

PATIENTS AND METHODS

In this open-label multicenter study, patients with uHCC received lenvatinib (bodyweight ≥ 60 kg, 12 mg; < 60 kg, 8 mg) orally daily and pembrolizumab 200 mg intravenously on day 1 of a 21-day cycle. The study included a dose-limiting toxicity (DLT) phase and an expansion phase (first-line patients). Primary objectives were safety/tolerability (DLT phase), and objective response rate (ORR) and duration of response (DOR) by modified RECIST (mRECIST) and RECIST version 1.1 (v1.1) per independent imaging review (IIR; expansion phase).

RESULTS

A total of 104 patients were enrolled. No DLTs were reported (n = 6) in the DLT phase; 100 patients (expansion phase; included n = 2 from DLT phase) had received no prior systemic therapy and had Barcelona Clinic Liver Cancer stage B (n = 29) or C disease (n = 71). At data cutoff, 37% of patients remained on treatment. Median duration of follow-up was 10.6 months (95% CI, 9.2 to 11.5 months). Confirmed ORRs by IIR were 46.0% (95% CI, 36.0% to 56.3%) per mRECIST and 36.0% (95% CI, 26.6% to 46.2%) per RECIST v1.1. Median DORs by IIR were 8.6 months (95% CI, 6.9 months to not estimable [NE]) per mRECIST and 12.6 months (95% CI, 6.9 months to NE) per RECIST v1.1. Median progression-free survival by IIR was 9.3 months per mRECIST and 8.6 months per RECIST v1.1. Median overall survival was 22 months. Grade ≥ 3 treatment-related adverse events occurred in 67% (grade 5, 3%) of patients. No new safety signals were identified.

CONCLUSION

Lenvatinib plus pembrolizumab has promising antitumor activity in uHCC. Toxicities were manageable, with no unexpected safety signals.

A phase Ib study of lenvatinib (LEN) plus pembrolizumab (PEMBRO) in unresectable hepatocellular carcinoma (uHCC)

4519

Background: LEN is a multikinase inhibitor of VEGFR 1–3, FGFR 1–4, PDGFRα, RET, and KIT, approved for first line (1L) treatment of uHCC. PEMBRO, an anti-PD-1 monoclonal antibody, was granted accelerated approval for the treatment of patients (pts) with HCC after sorafenib therapy. We assessed the safety and efficacy of LEN + PEMBRO in uHCC. Methods: In this phase 1b trial (NCT03006926), pts received LEN 12 mg/day (bodyweight [BW] ≥60 kg) or 8 mg/day (BW <60 kg) orally + PEMBRO 200 mg IV on Day 1 of a 21-day cycle. Primary endpoints were safety and tolerability for Part 1 and objective response rate (ORR) and duration of response (DOR) by mRECIST and RECIST v1.1 per independent imaging review (IIR) in the 1L setting for Part 2. Results: 104 pts (part 1, n=6; part 2, n=98) were enrolled. No DLTs were reported in Part 1; 100 pts were included in the 1L analysis of LEN + PEMBRO–4 pts (part 1) excluded due to prior sorafenib. At data cutoff (October 31, 2019) and median follow-up of 10.6 months, 37 pts continued treatment (LEN only, n=3; both drugs, n=34); median duration of treatment was 7.9 months (LEN, 7.6 months; PEMBRO, 7.4 months). Median OS was 22.0 months (95% CI 20.4–not estimable [NE]), median PFS was 8.6 months (95% CI 7.1–9.7), and ORR was 36% (95% CI 26.6–46.2) (RECIST v1.1 per IIR). Additional efficacy outcomes are shown in the table. Treatment-emergent adverse events (TEAEs) occurred in 99% of pts (grade ≥3, 85%; grade ≥4, 23%). The most common grade ≥3 TEAE was hypertension (18% of pts). Treatment-related AEs (TRAEs) occurred in 95% of pts (grade ≥3, 67%; grade ≥4, 4%). The most common grade ≥3 TRAE was hypertension (17% of pts). 36% of pts had serious TRAEs and 3 pts died from a TRAE (acute respiratory failure/acute respiratory distress syndrome, n=1; intestinal perforation, n=1; abnormal hepatic function, n=1). Conclusions: LEN + PEMBRO has promising antitumor activity with a tolerable safety profile. An ongoing phase 3 trial (NCT03713593) is assessing LEN + PEMBRO vs LEN alone as 1L therapy for uHCC. Clinical trial information: NCT03006926 . [Table: see text]

Lenvatinib (len) plus pembrolizumab (pembro) for the first-line treatment of patients (pts) with advanced hepatocellular carcinoma (HCC): Phase 3 LEAP-002 study

TPS4152

Background: Len, an inhibitor of VEGF receptors 1-3, FGF receptors 1-4, PDGF receptor α, RET, and KIT, is approved for first-line treatment of unresectable HCC (uHCC) based on the open-label phase 3 REFLECT study in which len showed noninferior overall survival (OS) and significantly improved objective response rate (ORR), progression-free survival (PFS), and time-to-progression (TTP) vs sorafenib. In the phase 2 KEYNOTE-224 study of pembro (a PD-1 inhibitor) as second-line treatment of advanced HCC, pembro showed meaningful clinical efficacy in pts previously treated with sorafenib, with median PFS 4.9 mo, median OS 12.9 mo, and a manageable safety profile. In results from the phase 1b KEYNOTE-524 trial, len+pembro was well-tolerated, with promising antitumor activity in pts with uHCC. LEAP-002 is a phase 3 study to evaluate the safety and efficacy of len+pembro vs len+placebo as first-line therapy for advanced HCC. Methods: Eligible pts are ≥18 y and have HCC confirmed by radiology, histology, or cytology; ECOG PS 0/1; BCLC stage C or stage B disease not amenable to locoregional therapy or curative treatment approach; CP class A liver score within 7 days before study; and ≥1 measurable lesion by RECIST v1.1. Pts with past or ongoing HCV infection and those with controlled HBV are eligible. 750 pts will be randomized 1:1 to receive len 12 mg (body weight [BW] ≥60 kg) or 8 mg (BW <60 kg) orally once daily plus pembro 200 mg or placebo IV Q3W. Pembro and len will be administered until disease progression or unacceptable toxicity, with a maximum 35 cycles for pembro. Stratification will be by geographic region (Asia vs Japan and Western regions); macroscopic portal vein invasion or extrahepatic spread or both (yes or no); alpha fetoprotein ≤400 ng/mL vs >400 ng/mL; and ECOG PS 0/1. Primary end points are PFS per RECIST v1.1 by blinded independent central review (BICR) and OS. Secondary end points are ORR, duration of response, disease control rate, and TTP per RECIST v1.1 by BICR, efficacy per modified RECIST, pharmacokinetics, and safety. Imaging assessments will be performed Q9W on study. AEs will be graded per CTCAE v4.0 and monitored up to 90 days after last dose. Clinical trial information: NCT03713593.

A therapeutic T cell receptor mimic antibody targets tumor-associated PRAME peptide/HLA-I antigens

Preferentially expressed antigen in melanoma (PRAME) is a cancer-testis antigen that is expressed in many cancers and leukemias. In healthy tissue, PRAME expression is limited to the testes and ovaries, making it a highly attractive cancer target. PRAME is an intracellular protein that cannot currently be drugged. After proteasomal processing, the PRAME300-309 peptide ALYVDSLFFL (ALY) is presented in the context of human leukocyte antigen HLA-A*02:01 molecules for recognition by the T cell receptor (TCR) of cytotoxic T cells. Here, we have described Pr20, a TCR mimic (TCRm) human IgG1 antibody that recognizes the cell-surface ALY peptide/HLA-A2 complex. Pr20 is an immunological tool and potential therapeutic agent. Pr20 bound to PRAME+HLA-A2+ cancers. An afucosylated Fc form (Pr20M) directed antibody-dependent cellular cytotoxicity against PRAME+HLA-A2+ leukemia cells and was therapeutically effective against mouse xenograft models of human leukemia. In some tumors, Pr20 binding markedly increased upon IFN-γ treatment, mediated by induction of the immunoproteasome catalytic subunit β5i. The immunoproteasome reduced internal destructive cleavages within the ALY epitope compared with the constitutive proteasome. The data provide rationale for developing TCRm antibodies as therapeutic agents for cancer, offer mechanistic insight on proteasomal regulation of tumor-associated peptide/HLA antigen complexes, and yield possible therapeutic solutions to target antigens with ultra-low surface presentation.

Mechanisms of leukemia resistance to antibody dependent cellular cytotoxicity

Specific immunotherapy for acute leukemia remains a great unmet need. Native unmodified monoclonal antibody therapies, while promising, are inadequately effective for these malignancies, and multiple mechanisms for failure have been described. Antibody-dependent cellular cytotoxicity or phagocytosis is the primary modality of mAb-mediated cell killing in vivo, but ultimately leads to relapse of the leukemias, in model systems and in humans. By use of a T-cell receptor mimic mAb ESKM, derived against a WT1 peptide expressed in complex with HLA-A*02:01, whose only mechanism of therapeutic action is ADCC, we evaluated the mechanisms of leukemic relapse from its potent therapeutic action in mouse xenograft models of human leukemia. Leukemia escape was not associated with loss of the antigenic target, downregulation of cell surface HLA, antibody pharmacokinetic or biodistribution issues, or development of leukemia cell-intrinsic resistance to ADCC. Interestingly, the rapidity of leukemic growth determined whether leukemia was able to evade cytotoxicity independent of the presence of sufficient effector cells. By engineering leukemia cells with upregulated p27^Kip1 and slower cell cycling times, we show that relapse was inversely correlated with growth rates resulting in the eventual inadequacy of effector to target ratio. Moreover, lack of migration of effector cells into lymphomatous pockets of ALL also allowed local escape. Successful leukemia therapy with mAb might therefore be improved in similar situations by combination with measures to reduce burden and slow leukemia cell growth.

Abstract A055: Potent therapeutic and immunological effects of the first T-BiTE derived from a TCR-mimic antibody targeting intracellular oncoprotein WT1

Bi-specific T cell engager antibody (BiTE) therapy has recently emerged as an effective immunotherapy by redirecting polyclonal T cell cytotoxicity against cell surface protein on tumor cells. We generated the first BiTE construct derived from a TCR-mimic monoclonal antibody (mAb), ESK1, specific for a peptide from an intracellular oncoprotein, WT1, in the context of HLA-A*02:01 molecules. Despite the low density peptide/HLA-A2 complex on the cell surface, ESK-BiTE was able to selectively activate and induce proliferation of cytolytic human T cells to kill multiple leukemias and cancers in vitro and in mice. Surprisingly, we also discovered that in an autologous setting, ESK-BiTE induced a robust secondary CD8 T cell response specific for antigens other than WT1, including HLA-A2-restricted her2-neu-derived peptide 369-377, in patients with her2- positive ovarian cancer. Therefore, the study demonstrated a new vaccinal mechanism for BiTE mAb action that could contribute to more effective long-term therapeutic activity of BiTE's and further broaden their reach to other tumor antigens not previously known or originally targeted.

Citation Format: Tao Dao, Dmitry Pankov, Andrew Scott, Tatyana Korontsvit, Victoriya Zakhaleva, Manuel Direito de Morais Guerrerio, Yiyang Xu, Jingyi Xiang, Su Yan, Nicholas Veomett, Nicholas Veomett, Leonid Dubrovsky, Michael Curcio, Ekaterina Doubrovina, Cheng Liu, Richard J. O'Reilly, David A. Scheinberg. Potent therapeutic and immunological effects of the first T-BiTE derived from a TCR-mimic antibody targeting intracellular oncoprotein WT1. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A055.

T cell receptor mimic antibodies for cancer therapy

The major hurdle to the creation of cancer-specific monoclonal antibodies (mAb) exhibiting limited cross-reactivity with healthy human cells is the paucity of known tumor-specific or mutated protein epitopes expressed on the cancer cell surface. Mutated and overexpressed oncoproteins are typically cytoplasmic or nuclear. Cells can present peptides from these distinguishing proteins on their cell surface in the context of human leukocyte antigen (HLA). T cell receptor mimic (TCRm) mAb can be discovered that react specifically to these complexes, allowing for selective targeting of cancer cells. The state-of-the-art for TCRm and the challenges and opportunities are discussed. Several such TCRm are moving toward clinical trials now.

Therapeutic efficacy of an Fc-enhanced TCR-like antibody to the intracellular WT1 oncoprotein

PURPOSE

RMFPNAPYL (RMF), a Wilms' tumor gene 1 (WT1)-derived CD8 T-cell epitope presented by HLA-A*02:01, is a validated target for T-cell-based immunotherapy. We previously reported ESK1, a high avidity (Kd < 0.2 nmol/L), fully-human monoclonal antibody (mAb) specific for the WT1 RMF peptide/HLA-A*02:01 complex, which selectively bound and killed WT1(+) and HLA-A*02:01(+) leukemia and solid tumor cell lines.

EXPERIMENTAL DESIGN

We engineered a second-generation mAb, ESKM, to have enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) function due to altered Fc glycosylation. ESKM was compared with native ESK1 in binding assays, in vitro ADCC assays, and mesothelioma and leukemia therapeutic models and pharmacokinetic studies in mice. ESKM toxicity was assessed in HLA-A*02:01(+) transgenic mice.

RESULTS

ESK antibodies mediated ADCC against hematopoietic and solid tumor cells at concentrations below 1 μg/mL, but ESKM was about 5- to 10-fold more potent in vitro against multiple cancer cell lines. ESKM was more potent in vivo against JMN mesothelioma, and effective against SET2 AML and fresh ALL xenografts. ESKM had a shortened half-life (4.9 days vs. 6.5 days), but an identical biodistribution pattern in C57BL/6J mice. At therapeutic doses of ESKM, there was no difference in half-life or biodistribution in HLA-A*02:01(+) transgenic mice compared with the parent strain. Importantly, therapeutic doses of ESKM in these mice caused no depletion of total WBCs or hematopoetic stem cells, or pathologic tissue damage.

CONCLUSIONS

The data provide proof of concept that an Fc-enhanced mAb can improve efficacy against a low-density, tumor-specific, peptide/MHC target, and support further development of this mAb against an important intracellular oncogenic protein.

Therapeutic superiority of a TCR-like antibody to an intracellular WT1 oncogene peptide compared with the tyrosine kinase inhibitor imatinib in a mouse model of Philadelphia chromosome positive (Ph+) ALL

3047

Background: Acute and chronic leukemias demonstrate significantly increased expression of the Wilms tumor gene 1 (WT1) product, including CD34+ CML stem cells, making WT1 an attractive therapeutic target. However, WT1 protein is intracellular and currently un-druggable. ESKM is a fully human IgG1 antibody that targets a 9 amino acid sequence (RMF) of the protein WT1 in the context of HLA-A0201. Methods: BV173 is an HLA-A0201 positive Ph+ ALL cell line. It over-expresses WT1 and binds strongly to ESKM. We evaluated the in vitro and in vivo efficacy of ESKM in combination with TKIs. Antibody-dependent cell-mediated cytotoxicity (ADCC) was evaluated in vitro by chromium release assay, utilizing human PBMC effectors. In vivo tumor growth was assessed in NSG mice bearing disseminated luciferase tagged BV173 with bioluminescence imaging and flow cytometry of the bone marrow after sacrifice. Imatinib was used at maximum tolerated doses for these mice as determined in pilot studies. Results: The addition of imatinib in vitro did not affect the ability of ESKM to perform ADCC. The BV173 engrafted NSG mice treated with ESKM with and without TKIs showed tumor regression one week after beginning therapy, clearing leukemia from the liver and spleen. Mice relapsed primarily in the bone marrow, with increasing luciferase signal after two weeks of therapy. Compared to untreated control animals, after 5 weeks of therapy, imatinib alone only reduced tumor growth by 45%; ESKM alone reduced growth by 81%, and the combination of ESKM and imatinib reduced growth by more than 95%. Flow cytometry of cells remaining after treatment showed binding of ESKM, suggesting escape was not due to down regulation of the epitope. Conclusions: In this mouse model of Ph+ ALL, ESKM antibody therapy is superior to imatinib and the combination of both modalities is additive. This antibody is efficacious in vitro and in vivo against WT1 overexpressing leukemias, in context of HLA-A0201. This combination holds promise as a therapy for leukemias in patients who are HLA-A0201 positive, with the potential of improved cytoreduction in patients with Ph+ leukemias.

Analysis of pediatric autologous PBSC apheresis and transplant: age is a major factor affecting post-transplant toxicity

BACKGROUND

High-dose chemotherapy followed by autologous hematopoietic cell transplantation (HCT) is used in many therapeutic protocols for pediatric intra- and extra-cranial solid tumors. HCT can be curative, but is associated with significant toxicity.

PROCEDURE

Between January 2001 and June 2009, 92 solid tumor patients (age 6 months to 27 years) underwent 94 autologous apheresis procedures at Children's National Medical Center. Out of that group, 71 patients, who underwent 162 autologous HCT, were analyzed for transplant outcomes. Multiple variable modeling was used to identify independent variables related to transplant toxicity outcome measures, such as bacteremia, intensive care admission, and death. Other outcome measures (time to pre-apheresis peripheral blood CD34+ count, product yield, and time to engraftment) were also analyzed. Independent variables included patient-specific variables (age, weight, tumor type, chemotherapy administered, and primary vs. relapsed disease) and harvest or transplant-related variables (total white blood cell and CD34+ cell counts prior to transplant, and quantity of total nucleated cells and CD34+ cells infused during transplant).

RESULTS

Transplant toxicity was significantly greater in younger patients (P = 0.001) and in neuroblastoma patients (P = 0.003). The time to neutrophil engraftment, controlling for weight, age, and chemotherapy, was positively related to absolute CD34+ cells/kg infused (P = 0.01). The time to CD34+ recovery pre-apheresis was affected by patient diagnosis (P = 0.05).

CONCLUSIONS

Younger patients had increased transplant toxicity, with infants <1 year of age at highest risk for fever, bacteremia, admission to intensive care, and death. Infants would likely benefit from hospitalization after autologous HCT until neutrophil recovery.

Sequence Context Modulates the Stability of a GxxxG-mediated Transmembrane Helix–Helix Dimer

To quantify the relationship between sequence and transmembrane dimer stability, a systematic mutagenesis and thermodynamic study of the protein-protein interaction residues in the glycophorin A transmembrane helix-helix dimer was carried out. The results demonstrate that the glycophorin A transmembrane sequence dimerizes when its GxxxG motif is abolished by mutation to large aliphatic residues, suggesting that the sequence encodes an intrinsic propensity to self-associate independent of a GxxxG motif. In the presence of an intact GxxxG motif, the glycophorin A dimer stability can be modulated over a span of -0.5 kcal mol(-1) to +3.2 kcal mol(-1) by mutating the surrounding sequence context. Thus, these flanking residues play an active role in determining the transmembrane dimer stability. To assess the structural consequences of the thermodynamic effects of mutations, molecular models of mutant transmembrane domains were constructed, and a structure-based parameterization of the free energy change due to mutation was carried out. The changes in association free energy for glycophorin A mutants can be explained primarily by changes in packing interactions at the protein-protein interface. The energy cost of removing favorable van der Waals interactions was found to be 0.039 kcal mol(-1) per A2 of favorable occluded surface area. The value corresponds well with estimates for mutations in bacteriorhodopsin as well as for those mutations in the interiors of soluble proteins that create packing defects.

Lipopolysaccharide stimulates HIV-1 entry and degradation in human macrophages

The bacterial endotoxin LPS is a potent stimulator of monocyte and macrophage activation and has been shown to protect differentiated macrophages from de novo infection by HIV-1. However, the mechanisms of this inhibitory activity of LPS are not fully understood. We investigated the effect of LPS on the early post-binding steps of HIV-1 replication in primary macrophages. Paradoxically, when applied together with the virus, LPS stimulated entry of HIV-1 into macrophages, as judged by the amount of internalized HIV-1 RNA and p24. This stimulatory activity did not depend on receptors used for entry and did not require new protein synthesis. However, internalized viral RNA and p24 were rapidly degraded in LPS-stimulated macrophages. Surprisingly, while degradation of HIV-1 p24 in LPS-treated cells was inhibited by bafilomycin A1, HIV-1 RNA was not protected by this agent, suggesting that viral RNA is degraded by a pH-independent mechanism. These results indicate that LPS stimulates both virus uptake and virus degradation in macrophages.

CD147 facilitates HIV-1 infection by interacting with virus-associated cyclophilin A

Cyclophilin A (CyPA) is specifically incorporated into the virions of HIV-1 and has been shown to enhance significantly an early step of cellular HIV-1 infection. Our preliminary studies implicated CD147 as a receptor for extracellular CyPA. Here, we demonstrate a role for CyPA-CD147 interaction during the early steps of HIV-1 infection. Expression of human CD147 increased infection by HIV-1 under one-cycle conditions. However, susceptibility to infection by viruses lacking CyPA (simian immunodeficiency virus or HIV-1 produced in the presence of cyclosporin A) was unaffected by CD147. Virus-associated CyPA coimmunoprecipitated with CD147 from infected cells. Antibody to CD147 inhibited HIV-1 entry as evidenced by the delay in translocation of the HIV-1 core proteins from the membrane and inhibition of viral reverse transcription. Viruses whose replication did not require CyPA (SIV or mutant HIV-1) were resistant to the inhibitory effect of anti-CD147 antibody. These results suggest that HIV-1 entry depends on an interaction between virus-associated CyPA and CD147 on a target cell.

Heat-shock protein 70 can replace viral protein R of HIV-1 during nuclear import of the viral preintegration complex

Heat-shock proteins (Hsp's) are a family of molecular chaperones that contribute to protection from environmental stress. In this report, we demonstrate that a member of this family, Hsp70, facilitates nuclear import of HIV-1 preintegration complexes (PICs). The mechanism of this activity appears to be similar to the one used by Vpr, an HIV-1 protein regulating viral nuclear import and replication in macrophages. Indeed Hsp70 stimulated binding of HIV-1 matrix antigen to GST-karyopherin alpha fusion protein and rescued nuclear import of a Vpr-defective HIV-1 strain in vitro. Binding studies with truncated forms of GST-karyopherin alpha demonstrated that both Vpr and Hsp70 bind to a region in the amino-terminal part of the karyopherin alpha molecule. This region appears to be distinct from the binding sites for two other karyopherin alpha cargoes, basic-type NLS-containing proteins and transcription factor STAT-1. Vpr competed with Hsp70 for binding to karyopherin alpha. These results suggest the presence of a novel regulatory site on karyopherin alpha which is used by Hsp70 and Vpr to stimulate interaction between the HIV-1 PIC and karyopherin alpha and thus promote viral nuclear import.

Small molecule inhibitor of HIV-1 nuclear import suppresses HIV-1 replication in human lymphoid tissue ex vivo: a potential addition to current anti-HIV drug repertoire

Despite recent progress in anti-HIV therapy, which has to do mainly with introduction of protease inhibitors into clinical practice, drug toxicity and emergence of drug-resistant isolates during the long-term treatment of the patients necessitates search for new drugs that can be added to currently used components of a multi-drug cocktail in highly active anti-retroviral therapy (HAART). Recently, we described a class of arylene bis(methylketone) compounds that inhibit nuclear import of HIV-1 pre-integration complexes and suppress viral replication in macrophages and PBMC in vitro. In this report, we demonstrate that one of these compounds, CNI-H1194, inhibited HIV-1 replication in primary lymphoid tissue ex vivo. The compound did not antagonize the activity of currently used anti-HIV drugs that inhibit viral reverse transcriptase or protease. These results suggest that arylene bis(methylketone) compounds might be a valuable addition to HAART.

Two nuclear localization signals in the HIV-1 matrix protein regulate nuclear import of the HIV-1 pre-integration complex

Replication of HIV-1 in non-dividing and slowly proliferating cell populations depends on active import of the viral pre-integration complex (PIC) into the cell nucleus. While it is commonly accepted that this process is mediated by an interaction between the HIV-1 PIC and the cellular nuclear import machinery, controversial results have been reported concerning the mechanisms of this interaction. Here, we demonstrate that a recently identified nuclear localization signal within the HIV-1 matrix protein (MA), MA NLS-2, together with previously described MA NLS-1, mediates nuclear import of the HIV-1 PIC. Inactivation of both MA NLSs precluded nuclear translocation of MA and rendered the virus defective in nuclear import and replication in non-dividing macrophage cultures, even when functional Vpr and integrase (IN), two more viral proteins implicated in HIV-1 nuclear import, were present. Taken together, these results indicate that Vpr does not function as an independent nuclear import factor and demonstrate that HIV-1 MA, by virtue of its two nuclear localization signals, regulates HIV-1 nuclear import.

Nitric oxide regulates MIP-1alpha expression in primary macrophages and T lymphocytes: implications for anti-HIV-1 response

BACKGROUND

Chemokines and chemokine receptors have been shown to play a critical role in HIV infection. Chemokine receptors have been identified as coreceptors for viral entry into susceptible target cells, and several members of the beta chemokine subfamily of cytokines, MIP-1alpha, MIP-1beta, and RANTES, have been identified as the major human immunodeficiency virus (HIV)-suppressive factors produced by activated CD8+ T lymphocytes. In macrophages, HIV-1 infection itself was shown to upregulate the production of MIP-1alpha and MIP-1beta. In the present study, we address the mechanisms by which HIV-1 infection regulates beta chemokine responses in macrophages and lymphocytes.

MATERIAL AND METHODS

To address whether nitric oxide (NO), generated as a consequence of HIV-1 infection, regulates beta chemokine responses in monocyte/macrophages and/or macrophage-depleted peripheral blood mononuclear cells (PBMCs) these two cell populations were isolated from HIV seronegative donors, placed in culture, and infected with HIV-1 in either the presence or absence of exogenous activators (e.g. lipopolysaccharide, phytohemagglutinin), inhibitors of nitric oxide synthase (NOS), or chemical donors of NO. Cultures were analyzed for beta chemokine responses by ELISA and RNase protection.

RESULTS

LPS-induced MIP-1alpha release is enhanced in HIV-1-infected, as compared to uninfected, monocyte/macrophage cultures, and this enhancing effect is partially blocked by the addition of inhibitors of NOS, and can be reproduced by chemical generators of NO even in the absence of HIV-1 infection. A similar strategy was used to demonstrate a role for NO in HIV-1-mediated induction of MIP-1alpha in unstimulated macrophage cultures. NOS inhibitors also decreased MIP-1alpha and MIP-1beta production by phytohemagglutinin-stimulated monocyte-depleted PBMC cultures.

CONCLUSIONS

These results indicate that NO amplifies MIP-1alpha responses in activated macrophages and lymphocytes, and suggests that this pleiotropic molecule might function as an enhancing signal that regulates secretion of beta chemokines during HIV-1 infection. These findings reveal a novel mechanism by which NO might regulate the anti-HIV activity of immune cells.

Lipopolysaccharide inhibits HIV-1 infection of monocyte- derived macrophages through direct and sustained down-regulation of CC chemokine receptor 5

It is now well established that HIV-1 requires interactions with both CD4 and a chemokine receptor on the host cell surface for efficient infection. The expression of the CCR5 chemokine receptor in human macrophages facilitates HIV-1 entry into these cells, which are considered important in HIV pathogenesis not only as viral reservoirs but also as modulators of altered inflammatory function in HIV disease and AIDS. LPS, a principal constituent of Gram-negative bacterial cell walls, is a potent stimulator of macrophages and has been shown to inhibit HIV infection in this population. We now present evidence that one mechanism by which LPS mediates its inhibitory effect on HIV-1 infection is through a direct and unusually sustained down-regulation of cell-surface CCR5 expression. This LPS-mediated down-regulation of CCR5 expression was independent of de novo protein synthesis and differed from the rapid turnover of these chemokine receptors observed in response to two natural ligands, macrophage-inflammatory protein-1alpha and -1beta. LPS did not act by down-regulating CCR5 mRNA (mRNA levels actually increased slightly after LPS treatment) or by enhancing the degradation of internalized receptor. Rather, the observed failure of LPS-treated macrophages to rapidly restore CCR5 expression at the cell-surface appeared to result from altered recycling of chemokine receptors. Taken together, our results suggest a novel pathway of CCR5 recycling in LPS-stimulated human macrophages that might be targeted to control HIV-1 infection.

Role of cyclophilin A in the uptake of HIV-1 by macrophages and T lymphocytes

Cyclophilins are a family of proteins that bind cyclosporin A (CsA) and possess peptidyl-prolyl cis-trans isomerase activity. In addition, they are secreted by activated cells and act in a cytokine-like manner, presumably via signaling through a cell surface cyclophilin receptor. More recently, host-derived cyclophilin A (CyPA) has been shown to be incorporated into HIV-1 virions and its incorporation essential for viral infectivity. Here we present evidence supporting a role for viral-associated CyPA in the early events of HIV-1 infection. We report that HIV-1 infection of primary peripheral blood mononuclear cells can be inhibited by: (i) an excess of exogenously added CyPA; (ii) a CsA analogue unable to enter the cells; (iii) neutralizing antibodies to CyPA. Taken together with our observations that recombinant CyPA-induced mobilization of calcium in immortalized, as well as primary, CD4+ T lymphocytes, and that incubation of T cells with iodinated CyPA, followed by chemical cross-linking, resulted in the formation of a high molecular mass complex on the cell surface, these results suggest that HIV-1-associated CyPA mediates an early event in viral infection via interaction with a cellular receptor. This interaction may present a target for anti-HIV therapies and vaccines.

The critical role of p38 MAP kinase in T cell HIV-1 replication

BACKGROUND

Replication of HIV-1 in human T lymphocytes requires the activation of host cellular proteins. This study identifies p38 mitogen-activated protein kinase (MAPK) as one such kinase necessary for HIV-1 replication in T cells.

MATERIALS AND METHODS

Primary human T lymphocytes were infected with the LAI strain of HIV-1 and Jurkat cells were infected with the RF strain of HIV-1. HIV replication was measured by reverse transcriptase activity. Cellular expression of endogenous p38 MAPK protein was analyzed using immunoprecipitation. Blockade of p38 MAPK expression was achieved using antisense oligonucleotides to p38 MAPK and the guanylhydrazone compound CNI-1493, an inhibitor of p38 MAPK activation.

RESULTS

HIV-1 infection of both primary human T lymphocytes and a T cell line rapidly activated the cellular p38 MAPK pathway, which remained activated for the duration of the culture. Addition of phosphothioated antisense oligonucleotides to p38 MAPK specifically inhibited viral replication. Blockade of p38 MAPK activation by addition of CNI-1493 also inhibited HIV-1 viral replication of primary T lymphocytes in a dose- and time-dependent manner. Stimulation of p38 MAPK activation did not occur with the addition of heat-inactivated virus, suggesting that viral internalization, and not just membrane binding, is necessary for p38 MAPK activation.

CONCLUSIONS

These results indicate that activation of the p38 MAPK cascade is critical for HIV-1 replication in primary T lymphocytes, and that blockade of this signal transduction pathway may be a novel therapeutic approach to the treatment of HIV-1 infection.

Critical role of reverse transcriptase in the inhibitory mechanism of CNI-H0294 on HIV-1 nuclear translocation

HIV-1 replication requires the translocation of viral genome into the nucleus of a target cell. We recently reported the synthesis of an arylene bis(methyl ketone) compound (CNI-H0294) that inhibits nuclear targeting of the HIV-1 genome and thus HIV-1 replication in monocyte cultures. Here we demonstrate that CNI-H0294 inhibits nuclear targeting of HIV-1-derived preintegration complexes by inactivating the nuclear localization sequence of the HIV-1 matrix antigen in a reaction that absolutely requires reverse transcriptase. This drug/reverse transcriptase interaction defines the specificity of its antiviral effect and is most likely mediated by the pyrimidine side-chain of CNI-H0294. After binding to reverse transcriptase, the carbonyl groups of CNI-H0294 react with the nuclear localization sequence of matrix antigen and prevent its binding to karyopherin alpha, the cellular receptor for nuclear localization sequences that carries proteins into the nucleus. Our results provide a basis for the development of a novel class of compounds that inhibit nuclear translocation and that can, in principle, be modified to target specific infectious agents.

A critical role of nitric oxide in human immunodeficiency virus type 1-induced hyperresponsiveness of cultured monocytes

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) infection leads to a general exhaustion of the immune system. Prior to this widespread decline of immune functions, however, there is an evident hyperactivation of the monocyte/macrophage arm. Increased levels of cytokines and other biologically active molecules produced by activated monocytes may contribute to the pathogenesis of HIV disease both by activating expression of HIV-1 provirus and by direct effects on cytokine-sensitive tissues, such as lung or brain. In this article, we investigate mechanisms of hyperresponsiveness of HIV-infected monocytes.

MATERIALS AND METHODS

The study was performed on monocyte cultures infected in vitro with a monocytetropic strain HIV-1ADA. Cytokine production was induced by stimulation of cultures with lipopolysaccharides (LPS) and measured by ELISA. To study involvement of nitric oxide (NO) in the regulation of cytokine expression, inhibitors of nitric oxide synthase (NOS) or chemical donors of NO were used.

RESULTS

We demonstrate that infection with HIV-1 in vitro primes human monocytes for subsequent activation with LPS, resulting in increased production of pro-inflammatory cytokines tumor necrosis factor (TNF) and interleukin 6 (IL-6). This priming effect can be blocked by Ca(2+)-chelating agents and by the NOS inhibitor L-NMMA, but not by hemoglobin. It could be reproduced on uninfected monocyte cultures by using donors of NO, but not cGMP, together with LPS.

CONCLUSIONS

NO, which is expressed in HIV-1-infected monocyte cultures, induces hyperresponsiveness of monocytes by synergizing with calcium signals activated in response to LPS stimulation. This activation is cGMP independent. Our findings demonstrate the critical role of NO in HIV-1-specific hyperactivation of monocytes.

Human immunodeficiency virus type 1 infection alters chemokine beta peptide expression in human monocytes: implications for recruitment of leukocytes into brain and lymph nodes

Two chemokine (chemoattractant cytokines) beta peptides, macrophage inflammatory proteins 1 alpha and 1 beta (MIP-1 alpha and MIP-1 beta), were induced in human monocyte cultures following infection with the human immunodeficiency virus type 1 (HIV-1). Induction depended on productive viral infection: not only did the kinetics of MIP-1 peptide induction closely follow those of viral replication, but monocyte cultures inoculated with heat-inactivated virus or infected in the presence of AZT failed to produce these chemokine beta peptides. In addition, HIV infection markedly altered the pattern of beta chemokine expression elicited by tumor necrosis factor (TNF), itself a potent proinflammatory cytokine upregulated during the development of AIDS. Reverse transcription (RT)-PCR and RT-in situ PCR studies on brain tissue from patients with AIDS dementia demonstrated elevated MIP-1 alpha and MIP-1 beta mRNA expression relative to comparable samples from HIV-1-infected patients without dementia. Cells expressing chemokines in HIV-1-infected brains were identified morphologically as microglia and astrocytes. As MIP-1 alpha and MIP-1 beta are potent chemoattractants for both monocytes and specific subpopulations of lymphocytes, this dysregulation of beta chemokine expression may influence the trafficking of leukocytes during HIV infection. These data, taken together, suggest a mechanism by which HIV-1-infected monocytes might recruit uninfected T cells and monocytes to sites of active viral replication or inflammation, notably the brain and lymph nodes.

Anti-idiotypic antibody to the V3 domain of gp120 binds to vimentin: a possible role of intermediate filaments in the early steps of HIV-1 infection cycle

Although the CD4 molecule is the major cellular receptor for human immunodeficiency virus (HIV), several lines of evidence suggest participation of additional molecules that are engaged after the binding of HIV to the CD4 receptor and that may facilitate viral entry into the target cell. Some of the post-CD4 binding, perfusion events involve the third hypervariable region (V3 loop) of the viral envelope protein gp120. To identify cellular proteins that interact with the V3 loop, we chose as a probe an antiidiotypic monoclonal antibody (MAb), anti-id2, which was prepared against the neutralizing MAb 110.4 that binds the V3 domain in the envelope glycoprotein gp120 of the LAI isolate of HIV-1. Anti-id2 reacted specifically with a 55- to 60-kDa protein in human T cell and monocytoid cell lines, and in a mouse melanoma cell line. This protein was identified immunologically and by protein sequence analysis as vimentin, an intermediate filament protein of lymphoid and other cells of mesodermal origin. Antiserum raised against vimentin inhibited nuclear translocation of HIV-1 DNA following infection of monocytes and CD4+ T cells with live virus, and reduced the amount of HIV-1 gag-specific RNA in the nuclei of monocytes following inoculation with HIV-1 pseudovirions. These data suggest that vimentin may participate in the early steps of HIV-1 replication, perhaps during the uptake of HIV-1 preintegration complexes into the nuclear compartment.

Prospective study of lactose absorption during cancer chemotherapy: feasibility of a yogurt-supplemented diet in lactose malabsorbers

Chemotherapy is a recognized cause of morphological alterations to the proximal intestine. Lactose malabsorption, the functional consequence of a small intestinal enzymatic derangement, has been shown to play an important role in causing gastrointestinal symptoms in subjects receiving chemotherapy. To establish a rational basis for the exclusion of lactose from the diet and to reduce the risk of developing gastrointestinal symptoms, we conducted a study of lactose absorption in 20 children during cancer chemotherapy. Because lactose is an important nutritional sugar, the tolerance of lactose provided by yogurt was examined. Lactose absorption was investigated by a hydrogen breath test (BT) after oral ingestion of milk (250 ml) containing physiological doses of lactose (12 g). The effect of yogurt supplementation was also tested by BT after meals of yogurt (450 g) also containing physiological doses of lactose (12.1 g). In 11 children, lactose malabsorption was detected by BT during the study before any gastrointestinal symptom revealed this status. Of these 11 children, no gastrointestinal discomfort developed in five receiving a lactose-excluded diet. In contrast, in the six children not restricted in lactose intake, gastrointestinal symptoms were observed 4 to 13 weeks after lactose malabsorption was detected by BT. The findings of our study suggested the usefulness of dietary supplementation with yogurt, a lactose-containing food, in children who developed lactose malabsorption. In fact, all lactose-malabsorbent children showed good lactose absorption and tolerance when tested by yogurt BT.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of nitric oxide synthase activity in human immunodeficiency virus type 1 (HIV-1)-infected monocytes: implications for HIV-associated neurological disease

Mononuclear phagocytes (monocytes, macrophages, and dendritic cells) play major roles in human immunodeficiency virus (HIV) persistence and disease pathogenesis. Macrophage antigen presentation and effector cell functions are impaired by HIV-1 infection. Abnormalities of macrophage effector cell function in bone marrow, lung, and brain likely result as a direct consequence of cellular activation and HIV replication. To further elucidate the extent of macrophage dysfunction in HIV-1 disease, a critical activation-specific regulatory molecule, nitric oxide (NO.), which may contribute to diverse pathology, was studied. Little, if any, NO. is produced by uninfected human monocytes. In contrast, infection with HIV-1 increases NO. production to modest, but significant levels (2-5 microM). Monocyte activation (with lipopolysaccharide, tumor necrosis factor alpha, or through interactions with astroglial cells) further enhances NO. production in HIV-infected cells, whereas its levels are diminished by interleukin 4. These results suggest a possible role for NO. in HIV-associated pathology where virus-infected macrophages are found. In support of this hypothesis, RNA encoding the inducible NO synthase (iNOS) was detected in postmortem brain tissue from one pediatric AIDS patient with advanced HIV encephalitis. Corresponding iNOS mRNA was not detected in brain tissue from five AIDS patients who died with less significant brain disease. These results demonstrate that HIV-1 can influence the expression of NOS in both cultured human monocytes and brain tissue. This newly described feature of HIV-macrophage interactions suggests previously unappreciated mechanisms of tissue pathology that result from productive viral replication.

Nuclear localization signal of HIV-1 as a novel target for therapeutic intervention

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) is a lentivirus and shares with other members of this retroviral subfamily the ability to replicate in nondividing cells, in particular, cells of the monocyte/macrophage lineage. This feature relies on the presence of a specific nuclear localization signal (NLS) within the viral matrix protein (MA p17), which to some degree can be complemented by the activity of the viral vpr gene product. The MA p17 NLS ensures efficient transportation of the viral preintegration complex into the nucleus of an infected macrophage and confers persistence of HIV-1 in quiescent T cells, and therefore presents an attractive target for therapeutic intervention.

MATERIALS AND METHODS

Nuclear localization signals (NLS) in general and the HIV-1 MA p17 NLS in particular are characterized by a stretch of positively charged amino acids including one or more lysine residues. A series of compounds potentially capable of binding and reacting with lysine by forming Schiff base adducts was synthesized. Our special consideration was to make compounds that would preferentially bind to two closely contiguous amino functions, as opposed to isolated single lysine residues. We assumed that this approach might specifically target the compound to NLS while affecting other regions less, thus reducing nonspecific cytotoxicity. Antiviral activity was assessed in primary monocytes and in peripheral blood lymphocytes (PBL) infected with HIV-1ADA strain. Viral replication was monitored by reverse transcriptase (RT) activity in the supernatant. Efficiency of nuclear importation of the viral preintegration complex was estimated by the formation of 2-LTR circle forms of HIV-1 DNA and also by in situ PCR techniques.

RESULTS

Arylene bis(methyl ketone) compounds with a nitrogenous third subsituent, especially a pyrimidinic side-chain, inhibited HIV-1 replication in human monocytes at an IC50 as low as 1 nM. These compounds did not block HIV-1 replication in peripheral blood lymphocyte cultures. The inhibitory effect observed in monocyte cultures appeared in the context of markedly reduced nuclear importation of viral DNA in the presence of the drug. No cytotoxic effects of the compounds was observed in vitro at concentrations as high as 10 microM. An amidinohydrazone derivative of the most active compound was about 100 times less active than the parent, indicating that carbonyl groups were instrumental in the antiviral effect.

CONCLUSIONS

These early results suggest that retroviral replication in nondividing cells is susceptible to pharmaceutical intervention targeted against the NLS activity of HIV-1 proteins in the viral preintegration complex. The compounds described efficiently block translocation of viral DNA to the nuclei of infected primary monocytes, and inhibit viral replication. This inhibition is effective only in nondividing cells and is not seen in proliferating cultures, such as activated PBLs. Thus, drugs that target HIV-1 NLS may be useful to specifically block the macrophage arm of HIV infection and could thereby be of value in treating macrophage-specific manifestations of HIV disease, such as HIV-1 dementia. In combination with other drugs, potential therapeutics exploiting this target may also help to control the progression of HIV-1 infection and disease.