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PURPOSE CMB305 is a heterologous prime-boost vaccination regimen created to prime NY-ESO-1–specific CD8 T-cell populations and then activate the immune response with a potent TLR-4 agonist. This open-label randomized phase II trial was designed to investigate the efficacy and safety of adding the CMB305 regimen to atezolizumab (anti–programmed death ligand-1 therapy) in comparison with atezolizumab alone in patients with synovial sarcoma or myxoid liposarcoma. PATIENTS AND METHODS Patients with locally advanced, relapsed, or metastatic synovial sarcoma or myxoid liposarcoma (any grade) were randomly assigned to receive CMB305 with atezolizumab (experimental arm) or atezolizumab alone (control arm). The primary end points were progression-free survival (PFS) and overall survival (OS) analyzed using the Kaplan-Meier method. Safety and immune responses were assessed. RESULTS A total of 89 patients were enrolled; 55.1% had received ≥ 2 prior lines of chemotherapy. Median PFS was 2.6 months and 1.6 months in the combination and control arms, respectively (hazard ratio, 0.9; 95% CI, 0.6 to 1.3). Median OS was 18 months in both treatment arms. Patients treated with combination therapy had a significantly higher rate of treatment-induced NY-ESO-1–specific T cells ( P = .01) and NY-ESO-1–specific antibody responses ( P < .0001). In a post hoc analysis of all dosed patients, OS was longer (36 months) in the subset who developed anti-NY-ESO-1 T-cell immune response (hazard ratio, 0.3; P = .02). CONCLUSION Although the combination of CMB305 and atezolizumab did not result in significant increases in PFS or OS compared with atezolizumab alone, some patients demonstrated evidence of an anti-NY-ESO-1 immune response and appeared to fare better by imaging than those without such an immune response. Combining prime-boost vaccines such as CMB305 with anti–programmed death ligand-1 therapies merits further evaluation in other clinical contexts.

International audience; Intratumoral injection of G100, a toll-like receptor 4 (TLR4) agonist, was shown pre-clinically to stimulate anti-tumor immune responses and tumor regression. This open-label, multicenter, phase 1/2 trial evaluated the safety, tolerability, and preliminary efficacy of intratumoral G100 injections following localized low-dose radiation in patients with follicular lymphoma (ClinicalTrials.gov #NCT02501473). The study was comprised of a G100 dose escalation (5 or 10 mu g/dose, or 20 mu g/dose for large tumors); a randomized component comparing G100 to G100 plus pembrolizumab; and G100 20 mu g/dose expansion. Adverse events grade >= 3 were uncommon in patients treated with G100, and no unexpected toxicities were observed when combined with pembrolizumab. G100 20 mu g (n = 18) resulted in an overall response rate of 33.3% and abscopal tumor regression in 72.2% of patients. This early-phase study provides a foundation for combining an intratumoral TLR4 agonist with agents to produce immune-mediated responses in follicular lymphoma with limited added toxicity.

Background: The epidermal growth factor receptor (EGFR) is a potent oncogene commonly altered in many cancers, including glioblastoma (GBM) and non-small cell lung cancer (NSCLC). EGFR tyrosine kinase activity driven by common EGFR mutations can be inhibited by small molecules, however, resistance to available agents may be driven by mutations in the EGFR active kinase site or other regions. BDTX-1535 is an orally available, highly potent, selective, irreversible inhibitor of EGFR mutations, including extracellular variants and amplifications commonly expressed in GBM and inhibits the uncommon EGFR mutations found in NSCLC, including the C797S mutation acquired following 3rd generation EGFR inhibitor therapy. Preclinical data demonstrated the ability of BDTX-1535 to cross the blood-brain barrier and produce sustained inhibition of EGFR signaling. Preclinical studies suggest that BDTX-1535 has potential to be clinically active in suppressing tumor growth in patients with GBM and NSCLC with or without CNS metastases, including a potential survival benefit. Methods: BDTX-1535-101 (NCT05256290) is Phase 1, open-label, multicenter study to assess the safety, tolerability, PK, CNS penetrance, and preliminary antitumor activity of BDTX-1535 in recurrent GBM (rGBM) or locally advanced or metastatic NSCLC with or without CNS disease. The Monotherapy Dose Escalation portion will evaluate BDTX-1535 in patients with either rGBM expressing EGFR alterations or locally advanced/metastatic NSCLC harboring sensitizing EGFR mutations with or without CNS disease. Patients with rGBM must have previously received available standard therapy of surgical resection followed by chemoradiotherapy and/or temozolomide (TMZ). Eligible NSCLC patients must have EGFR mutated NSCLC that has progressed following standard of care EGFR inhibitor therapy. Once a provisional recommended Phase 2 dose (RP2D) has been established, BDTX-1535 monotherapy will be explored in the following Dose Expansion cohorts to further evaluate safety, PK, and preliminary assessment of efficacy: 1) rGBM with confirmed EGFR alterations, 2) NSCLC with uncommon EGFR mutations following EGFR inhibitor therapy; 3) NSCLC with acquired EGFR resistance mutation following a 3rd generation EGFR inhibitor in 1L setting. NSCLC patients may enroll with or without CNS metastases and must not be known to express excluded resistance mutations such as EGFR T790M or MET. BDTX-1535 will also be studied in combination with TMZ to assess safety, tolerability, and a recommended combination dose for the treatment of patients with rGBM harboring EGFR mutations or variants. Enrollment was initiated in 2022 and dose escalation is ongoing. Dose Expansion cohorts are expected to open in 2023. For additional information, please contact BDTX_1535_101_Study@bdtx.com Citation Format: Melissa Johnson, Jason Henry, Alex Spira, James Battiste, Iyad Alnahhas, Manmeet Ahluwalia, Minal Barve, Jeffrey Edenfield, DoHyun Nam, Sudharshan Eathiraj, Julio Hajdenberg, Sergey Yurasov, Helena Yu, Patrick Wen. A phase 1 study to assess BDTX-1535, an oral EGFR inhibitor, in patients with glioblastoma or non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT127.

Background Outcomes data regarding advanced synovial sarcoma (SS) and myxoid/round cell liposarcoma (MRCL) are limited, consisting primarily of retrospective series and post hoc analyses of clinical trials. Methods In this multi‐center retrospective study, data were abstracted from the medical records of 350 patients from nine sarcoma centers throughout the United States and combined into a registry. Patients with advanced/unresectable or metastatic SS (n = 249) or MRCL (n = 101) who received first‐line systemic anticancer therapy and had records of tumor imaging were included. Overall survival (OS), time to next treatment, time to distant metastasis, and progression‐free survival (PFS) were evaluated using the Kaplan‐Meier method and Cox regression. Results At start of first‐line systemic anticancer therapy, 92.4% of patients with SS and 91.1% of patients with MRCL had metastatic lesions. However, 74.7% of patients with SS and 72.3% of patients with MRCL had ≥2 lines of systemic therapy. Median OS and median PFS from first‐line therapy for SS was 24.7 months (95% CI, 20.9‐29.4) and 7.5 months, respectively (95% CI, 6.4‐8.4). Median OS and median PFS from start of first‐line therapy for MRCL was 29.9 months (95% CI, 27‐44.6) and 8.9 months (95% CI 4.5‐12.0). Conclusions To the best of our knowledge, this is the largest retrospective study of patients with SS and MRCL. It provides an analysis of real‐world clinical outcomes among patients treated at major sarcoma cancer centers and could inform treatment decisions and design of clinical trials. In general, the survival outcomes for this selected population appear more favorable than in published literature., This comprehensive analysis of real‐world outcomes in patients with advanced synovial sarcoma and myxoid round cell liposarcoma provides greater insight into clinical outcomes than previously published research. These data have the potential to inform prognosis and treatment decisions, as well as provide guidance in the development of future clinical trials.

Purpose Liquid biopsies represent an attractive alternative to tissue biopsies, particularly rebiopsies, in determining patient eligibility for targeted therapies. Clinical utility of urine genotyping, however, has not been explored extensively. We evaluated epidermal growth factor receptor ( EGFR) T790M detection in matched urine, plasma, and tissue and the clinical outcomes of patients with advanced non–small-cell lung cancer treated with rociletinib. Methods Tissue (n = 540), plasma (n = 482), and urine (n = 213) were collected from evaluable patients enrolled in TIGER-X, a phase I/II study. Genotyping was performed by therascreen EGFR testing in tissue, BEAMing in plasma, and a quantitative short footprint assay (Trovera) in urine, which was used to further examine discordant samples. Results Positive percent agreement with tissue T790M results was similar for urine (82%; 142 of 173) and plasma (81%; 313 of 387) genotyping. Urine and plasma together identified more patients who were T790M positive (92%) than tissue alone (83%) among matched samples (n = 177). The ability to identify mutations in plasma was strongly associated with M stage ( P < .001); rate of T790M detection for patients with M1a/M0 disease increased from 54% for plasma alone to 85% when urine and plasma were both examined. Objective response rates of patients who were T790M positive were comparable between tumor (34%), plasma (32%), and urine (37%). Conclusion Clinical response to rociletinib was comparable irrespective of whether T790M status was identified by liquid or tissue biopsy. Combined, urine and plasma identified a higher percentage of patients who were T790M positive than tumor genotyping alone and improved detection of T790M, particularly in the absence of distant metastases. These findings support the noninvasive analysis of urine and plasma before tumor rebiopsy when assessing T790M status.

BACKGROUND Vascular endothelial growth factor (VEGF)–mediated angiogenesis plays an important role in non–small cell lung cancer (NSCLC). Ramucirumab is a human immunoglobulin G1 monoclonal antibody that inhibits VEGF receptor 2. This phase 2 study investigated ramucirumab in combination with first-line pemetrexed and platinum chemotherapy in advanced/metastatic NSCLC. METHODS Eligible stage IV nonsquamous NSCLC patients with no prior chemotherapy for metastatic disease were randomized 1:1 to pemetrexed and carboplatin (or cisplatin) or ramucirumab (10 mg/kg) plus pemetrexed and carboplatin (or cisplatin) once every 3 weeks. Treatment was given for 4 to 6 cycles, and this was followed by a maintenance phase with pemetrexed or ramucirumab and pemetrexed. The primary endpoint was progression-free survival (PFS) with a sample size of sufficient power to detect an increase from 7 to 10.4 months. RESULTS From October 2010 to October 2011, 140 patients were randomized (pemetrexed-platinum arm, 71; ramucirumab-pemetrexed-platinum arm, 69), and most baseline characteristics were similar for the 2 treatment arms. The median PFS was 5.6 months for the pemetrexed-platinum arm and 7.2 months for the ramucirumab-pemetrexed-platinum arm (hazard ratio, 0.75; P = .132). The objective response rates were 38.0% and 49.3% for the pemetrexed-platinum and ramucirumab-pemetrexed-platinum arms, respectively (P = .180). The disease control rate was 70.4% for the pemetrexed-platinum arm and 85.5% for the ramucirumab-pemetrexed-platinum arm (P = .032). The grade 3 or higher adverse events occurring in 10% or more of patients were thrombocytopenia, neutropenia, fatigue, anemia, nausea, back pain, and hypertension. CONCLUSIONS The primary endpoint of significant prolongation of PFS was not met; however, ramucirumab showed evidence of clinical activity in combination with pemetrexed and platinum in nonsquamous NSCLC patients. The addition of ramucirumab to pemetrexed and platinum did not result in new or unexpected safety findings. Cancer 2015;121:883–892. © 2014 American Cancer Society.

Introduction The objective of this study was to determine whether the addition of ramucirumab to first-line paclitaxel–carboplatin chemotherapy in patients with advanced non–small-cell lung cancer (NSCLC) resulted in a 6-month progression-free survival (PFS) rate that compares favorably with the historic rate for bevacizumab combined with paclitaxel–carboplatin in this patient population. Methods In this phase II, single-arm, open-label, multicenter study, 40 patients with advanced NSCLC received ramucirumab (10 mg/kg intravenous [IV]) followed by paclitaxel (200 mg/m 2 IV) and carboplatin area under the curve=6 on day 1 every 21 days as first-line therapy. Therapy continued for up to six cycles. Patients not experiencing withdrawal criteria may have continued ramucirumab monotherapy every 3 weeks. The primary endpoint was PFS at 6 months, with 80% power to detect a 6-month PFS rate of at least 55%. Results The 6-month PFS rate was 59.0% and the objective response rate was 55.0%. The most common treatment-related adverse events were fatigue, peripheral neuropathy, nausea, epistaxis, and myalgia. Single-nucleotide polymorphism (SNP) rs2981582 on the FGFR-2 gene had significant associations with improved overall survival, PFS, and best overall response ( p values without multiplicity adjustment were 0.0059, 0.0429, and 0.0392, respectively). Conclusion Ramucirumab in combination with paclitaxel–carboplatin resulted in a 6-month PFS rate and safety profile that compared favorably with the historical control. In addition, no deaths were associated with this treatment. Furthermore, we describe an association of SNP on FGFR-2 gene with survival and response. These findings warrant further clinical investigation in patients with NSCLC.

11011 Background: CMB305 (C) is an immunotherapy designed to generate an anti-NY-ESO-1 immune response (IR). C consists of a dendritic cell-targeting lentiviral vector encoding NY-ESO-1 gene (LV305), and a TLR-4 agonist NY-ESO-1 recombinant protein plus GLA-SE (G305). A Phase 1 study demonstrated C is safe, generates IR and conveys a median overall survival (mOS) of 23.7 months (15.5, not reached [NR]) for soft tissue sarcomas & 29.2 months (12.2, NR) for synovial sarcoma (SS) (ESMO 2018). We evaluated efficacy and safety of C and atezolizumab (A) vs A alone in NY-ESO-1+ SS and myxoid round cell liposarcoma (MRCL). Methods: A prospective randomized open label phase 2 study of C (LV305 Intradermal Days 0, 14, 42, 70 + G305 Intramuscular Days 28, 56, 84 then q 6wk up to one year (yr)) + A (1200mg IV q3wk) vs A alone in advanced NY-ESO-1+ SS/MRCL. Primary endpoints of OS and progression-free survival (PFS); secondary endpoints of safety, IR, and response rate and post hoc analysis by line of therapy. Results: 88 patients (pts) were enrolled and dosed. Arm C+A: median age 48 yrs, 73% SS, 98% relapsed metastatic, 73% ≥2 prior lines chemotherapy; Arm A: 47 yrs, 67% SS, 84% relapsed metastatic, 53% ≥2 prior lines chemotherapy. Most treatment-related adverse events (TRAE) Grade 1/2, no treatment related deaths. Summary of clinical outcomes. Conclusions: Despite no major differences in PFS and OS between the treatment arms (Arm C+A had more advanced disease and more prior lines of chemotherapy), Arm A +C achieved PRs, a higher level of anti-NY-ESO-1 IR, and pts with IR had numerically superior outcomes. Moreover, the clinical benefit of C+A in earlier lines of therapy warrant further study. Clinical trial information: NCT02609984. [Table: see text]

Long-term humoral immunity is maintained by the formation of high-affinity class-switched memory B cells and long-lived antibody-secreting plasma cells. In healthy humans, a substantial fraction of IgG-positive memory B cells express self-reactive and polyreactive IgG antibodies that frequently develop by somatic mutations. Whether self- and polyreactive IgG-secreting B cells are also tolerated in the long-lived plasma cell pool is not known. To address this question, we cloned and expressed the Ig genes from 177 IgG-producing bone marrow plasma cells of four healthy donors. All antibodies were highly mutated but the frequency of self- and polyreactive IgG antibodies was significantly lower than that found in circulating memory B cells. The data suggest that in contrast to the development of memory B cells, entry into the bone marrow plasma cell compartment requires previously unappreciated selective regulation by mechanisms that limit the production of self- and polyreactive serum IgG antibodies.

We have developed an efficient strategy that combines immunoglobulin (Ig) gene repertoire analysis and Ig reactivity profiling at the single cell level. Based on surface marker expression individual cells at different stages of human B cell development are isolated by fluorescence-activated cell sorting. For each cell Ig heavy and corresponding Ig light chain gene transcripts are amplified by nested RT-PCR and cloned into eukaryotic expression vectors to produce monoclonal human antibodies of the same specificity in vitro. All reactions are performed in 96-well plates and allow cloning of large numbers of Ig genes. The recombinant antibodies are tested for reactivity with diverse self- and non-self antigens and the reactivity profile can be directly linked to the complete Ig heavy and Ig light chain gene sequence information that is obtained as part of the cloning strategy. In summary, our method to clone and express human monoclonal antibodies is unbiased, highly efficient, requires only small cell numbers and the recombinant antibodies allow direct conclusions on the frequency of specific human B cells in a diverse repertoire.

Purpose of review Significant progress has been made over recent years in uncovering the B-cell tolerance mechanisms that control development of autoreactive antibodies. This review examines current knowledge on the regulation and selection of autoreactive B cells in mouse models, and in healthy humans and patients with autoimmune disorders. Recent findings Autoreactive B cells undergo stringent selection either in the bone marrow or peripheral circulation by deletion, induction of anergy, or receptor editing. There is growing evidence that receptor editing represents the primary physiologic B-cell tolerance mechanism. Several checkpoints against autoreactive B cells have been established in bone marrow and peripheral blood of healthy humans. Recent studies demonstrate that some autoimmune disorders are associated with several alterations in B-cell tolerance checkpoints and often lead to a greater number of autoreactive B cells in the circulation. Summary Discovering the precise nature of B-cell tolerance alterations in patients with autoimmune diseases will lead to the identification of new targets for therapeutic interventions in patients with these disorders.

A majority of the antibodies expressed by nascent B cells in healthy humans are self-reactive, but most of these antibodies are removed from the repertoire during B cell development. In contrast, untreated systemic lupus erythematosus (SLE) patients fail to remove many of the self-reactive and polyreactive antibodies from the naive repertoire. Here, we report that SLE patients in clinical remission continue to produce elevated numbers of self-reactive and polyreactive antibodies in the mature naive B cell compartment, but the number of B cells expressing these antibodies is lower than in patients with active disease. Our finding that abnormal levels of self-reactive mature naive B cells persist in the majority of patients in clinical remission suggests that early checkpoint abnormalities are an integral feature of SLE.

Autoantibodies are removed from the repertoire at two checkpoints during B cell development in the bone marrow and the periphery. Despite these checkpoints, up to 20% of the antibodies expressed by mature naive B cells in healthy humans show low levels of self-reactivity. To determine whether self-reactive antibodies are also part of the antigen-experienced memory B cell compartment, we analyzed recombinant antibodies cloned from single circulating human IgM+ memory B cells. Cells expressing antibodies specific for individual bacterial polysaccharides were expanded in the IgM+ memory compartment. In contrast, B cells expressing self-reactive and broadly bacterially reactive antibodies were removed from the repertoire in the transition from naive to IgM+ memory B cell. Selection against self-reactive antibodies was implemented before the onset of somatic hypermutation. We conclude that a third checkpoint selects against self-reactivity during IgM+ memory B cell development in humans.

A cardinal feature of systemic lupus erythematosus (SLE) is the development of autoantibodies. The first autoantibodies described in patients with SLE were those specific for nuclei and DNA, but subsequent work has shown that individuals with this disease produce a panoply of different autoantibodies. Thus, one of the constant features of SLE is a profound breakdown in tolerance in the antibody system. The appearance of self-reactive antibodies in SLE precedes clinical disease, but where in the B cell pathway tolerance is first broken has not been defined. In healthy humans, autoantibodies are removed from the B cell repertoire in two discrete early checkpoints in B cell development. We found these checkpoints to be defective in three adolescent patients with SLE. 25–50% of the mature naive B cells in SLE patients produce self-reactive antibodies even before they participate in immune responses as compared with 5–20% in controls. We conclude that SLE is associated with abnormal early B cell tolerance.

Vascular endothelial growth factor (VEGF)-mediated angiogenesis plays an important role in non-small cell lung cancer (NSCLC). Ramucirumab is a human immunoglobulin G1 monoclonal antibody that inhibits VEGF receptor 2. This phase 2 study investigated ramucirumab in combination with first-line pemetrexed and platinum chemotherapy in advanced/metastatic NSCLC.Eligible stage IV nonsquamous NSCLC patients with no prior chemotherapy for metastatic disease were randomized 1:1 to pemetrexed and carboplatin (or cisplatin) or ramucirumab (10 mg/kg) plus pemetrexed and carboplatin (or cisplatin) once every 3 weeks. Treatment was given for 4 to 6 cycles, and this was followed by a maintenance phase with pemetrexed or ramucirumab and pemetrexed. The primary endpoint was progression-free survival (PFS) with a sample size of sufficient power to detect an increase from 7 to 10.4 months.From October 2010 to October 2011, 140 patients were randomized (pemetrexed-platinum arm, 71; ramucirumab-pemetrexed-platinum arm, 69), and most baseline characteristics were similar for the 2 treatment arms. The median PFS was 5.6 months for the pemetrexed-platinum arm and 7.2 months for the ramucirumab-pemetrexed-platinum arm (hazard ratio, 0.75; P = .132). The objective response rates were 38.0% and 49.3% for the pemetrexed-platinum and ramucirumab-pemetrexed-platinum arms, respectively (P = .180). The disease control rate was 70.4% for the pemetrexed-platinum arm and 85.5% for the ramucirumab-pemetrexed-platinum arm (P = .032). The grade 3 or higher adverse events occurring in 10% or more of patients were thrombocytopenia, neutropenia, fatigue, anemia, nausea, back pain, and hypertension.The primary endpoint of significant prolongation of PFS was not met; however, ramucirumab showed evidence of clinical activity in combination with pemetrexed and platinum in nonsquamous NSCLC patients. The addition of ramucirumab to pemetrexed and platinum did not result in new or unexpected safety findings.

Background Ramucirumab is a human IgG1 monoclonal antibody that targets the extracellular domain of VEGFR-2. We aimed to assess efficacy and safety of treatment with docetaxel plus ramucirumab or placebo as second-line treatment for patients with stage IV non-small-cell-lung cancer (NSCLC) after platinum-based therapy. Methods In this multicentre, double-blind, randomised phase 3 trial (REVEL), we enrolled patients with squamous or non-squamous NSCLC who had progressed during or after a first-line platinum-based chemotherapy regimen. Patients were randomly allocated (1:1) with a centralised, interactive voice-response system (stratified by sex, region, performance status, and previous maintenance therapy [yes vs no]) to receive docetaxel 75 mg/m 2 and either ramucirumab (10 mg/kg) or placebo on day 1 of a 21 day cycle until disease progression, unacceptable toxicity, withdrawal, or death. The primary endpoint was overall survival in all patients allocated to treatment. We assessed adverse events according to treatment received. This study is registered with ClinicalTrials.gov, number NCT01168973. Findings Between Dec 3, 2010, and Jan 24, 2013, we screened 1825 patients, of whom 1253 patients were randomly allocated to treatment. Median overall survival was 10·5 months (IQR 5·1-21·2) for 628 patients allocated ramucirumab plus docetaxel and 9·1 months (4·2-18·0) for 625 patients who received placebo plus docetaxel (hazard ratio 0·86, 95% CI 0·75-0·98; p=0·023). Median progression-free survival was 4·5 months (IQR 2·3-8·3) for the ramucirumab group compared with 3·0 months (1·4-6·9) for the control group (0·76, 0·68-0·86; p

To investigate the mechanism of HIV-1-induced hematopoietic abnormalities, we examined the effect of HIV-1 infection on the in vitro and in vivo behavior of precursor cells obtained from human fetal bone marrow (HFBM). After infection with the monocyte-tropic isolate HIV-1(ADA), HFBM cells displayed a significant decrease in their subsequent in vitro production of precursor cell colonies and a marked impairment in their engraftment of the bone marrow of irradiated SCID mice. By injecting retrovirally tagged, purified human CD34+ cells into HIV-1(ADA)-infected or uninfected human thymic tissue implanted in SCID mice, we demonstrated that HIV-1 infection also inhibited the in vivo differentiation of CD34+ cells into T cells. To determine the mechanism by which HIV-1 suppressed hematopoietic activity, we investigated whether HIV-1 infection induced apoptotic cell death in hematopoietic cells. Multiparameter flow cytometry with FITC-labeled annexin V and propidium iodide demonstrated that infection of the HFBM with monocyte-tropic, but not T cell line-tropic HIV-1, stimulated apoptosis in the CD34+ hematopoietic precursor population. The presence of a TNF-alpha inhibitor during exposure of the HFBM cells to HIV-1 substantially reduced the level of apoptosis of CD34+ cells and significantly decreased the repression of in vitro colony formation induced by HIV-1. However, inhibition of TNF-alpha during HFBM cell culture with HIV-1 did not restore their capacity to engraft SCID mice. Taken together, these results indicated that HIV-1 suppression of human hematopoietic cell maturation is a multifactoral phenomenon, a crucial element of which may be HIV-1-induced apoptosis of precursor cells mediated by TNF-alpha production.

Modified, human immunodeficiency virus (HIV)-inoculated thy/liv-SCID-hu mice were used to evaluate the in vivo efficacy of antiretroviral drugs. Ritonavir treatment alone initially suppressed plasma viremia, but the viremia recurred with the appearance of ritonavir-resistant HIV isolates. Multidrug therapy suppressed plasma HIV RNA to undetectable levels; however, plasma viremia returned after therapy was stopped, showing that the therapy did not completely suppress HIV infection in the thymic implant. When thy/liv-SCID-hu mice were treated with a combination of zidovudine, lamivudine, and ritonavir immediately after inoculation with HIV, cocultures of the thymic implants remained negative for HIV even 1 month after therapy was discontinued, suggesting that acute treatment can prevent the establishment of HIV infection. Thus, these modified thy/liv-SCID-hu mice should prove to be a useful system for evaluating the effectiveness of different antiretroviral therapies on acute and chronic HIV infection.

HIV entry into human cells is mediated by CD4 acting in concert with one of several members of the chemokine receptor superfamily. The resistance to HIV infection observed in individuals with defective CCR5 alleles indicated that this particular chemokine receptor plays a crucial role in the initiation ofin vivoHIV infection. Expression of human CD4 transgene does not render mice susceptible to HIV infection because of structural differences between human and mouse CCR5. To ascertain whether expression of human CD4 and CCR5 is sufficient to make murine T lymphocytes susceptible to HIV infection, thelckpromoter was used to direct the T cell-specific expression of human CD4 and CCR5 in transgenic mice. Peripheral blood mononuclear cells and splenocytes isolated from these mice expressed human CD4 and CCR5 and were infectible with selected M-tropic HIV isolates. Afterin vivoinoculation, HIV-infected cells were detected by DNA PCR in the spleen and lymph nodes of these transgenic mice, but HIV could not be cultured from these cells. This indicated that although transgenic expression of human CD4 and CCR5 permitted entry of HIV into the mouse cells, significant HIV infection was prevented by other blocks to HIV replication present in mouse cells. In addition to providingin vivoverification for the important role of CCR5 in T lymphocyte HIV infection, these transgenic mice represent a newin vivomodel for understanding HIV pathogenesis by delineating species-specific cellular factors required for productivein vivoHIV infection. These mice should also prove useful for the assessment of potential therapeutic and preventative modalities, particularly vaccines.

To develop an in vivo model wherein human hematopoiesis occurs, we transplanted severe combined immunodeficiency (SCID) mice with either human fetal bone marrow (HFBM) or human fetal liver (HFL). After transplantation of SCID mice with cultured HFBM (BM-SCID-hu mice) or HFL cells (Liv-SCID-hu mice), significant engraftment of the mouse bone marrow (BM) and population of the peripheral blood with human leukocytes was detected. Human colony-forming unit–granulocyte macrophage and burst forming unit-erythroid were detected in the BM of the BM-SCID-hu and Liv-SCID-hu mice up to 8 months after transplantation. When the HFBM or HFL cells were transduced with a retroviral vector before transplantation, integrated retroviral sequences were detected in human precursor cells present in the SCID mouse BM and in leukocytes circulating in the peripheral blood (PB) up to 7 months after transplantation. The PB of the BM-SCID-hu mice also became populated with human T cells after implantation with human thymic tissue, which provided a human microenvironment wherein human pre-T cells from the BM could mature. When the HFBM was retrovirally transduced before transplantation, integrated retrovirus was detected in sorted CD4+CD8+ double positive and CD4+ single positive cells from the thymic implant and CD4+ cells from the PB. Taken together, these data indicated that the BM of our BM-SCID-hu and Liv-SCID-hu mice became engrafted with retrovirally transduced human hematopoietic precursors that undergo the normal human hematopoietic program and populate the mouse PB with human cells containing integrated retroviral sequences. In addition to being a model for studying in vivo human hematopoiesis, these mice should also prove to be a useful model for investigating in vivo gene therapy using human stem/precursor cells.

9045Background: Rociletinib is an oral, irreversible tyrosine kinase inhibitor of mutant epidermal growth factor receptor. Previously, we reported that rociletinib is active at doses ≥ 500 mg BID i...

9001Background: Rociletinib is an oral inhibitor of mutant EGFR, including T790M. We compared EGFR mutation detection in circulating tumor DNA from blood and urine to that in matched tissue in TIGE...

This article describes the treatment rationale and study-related procedures for the A Randomized, Double-Blind, Phase 3 Study of Docetaxel and Ramucirumab Versus Docetaxel and Placebo in the Treatment of Stage IV Non-Small-Cell Lung Cancer Following Disease Progression after One Prior Platinum-Based Therapy (REVEL) study (I4T-MC-JVBA; ClinicalTrials.govNCT01168973). This international, randomized, placebo-controlled, double-blinded phase III trial examines the efficacy and safety of ramucirumab treatment administered in combination with docetaxel, as compared with docetaxel administered with placebo, in patients with stage IV non-small-cell lung cancer (NSCLC) whose disease progressed during or after first-line platinum-based chemotherapy with or without maintenance treatment. The primary end point is overall survival; secondary end points include progression-free survival, objective response rate, disease control rate, patient-reported outcomes, and assessment of safety and tolerability of ramucirumab. Eligible patients (enrollment N = 1242) are randomized at a 1:1 ratio to receive either docetaxel (75 mg/m(2)) plus ramucirumab (10 mg/kg) (Arm A) or docetaxel (75 mg/m(2)) plus placebo (Arm B). Both drugs are administered via intravenous infusion once every 3 weeks until evidence of disease progression, unacceptable toxicity, noncompliance, or patient's consent withdrawal. Efficacy and safety will be compared between the study arms and in patient subgroups including patients with nonsquamous versus squamous tumor histology and patients who received prior bevacizumab treatment. Multiple blood and tumor tissue biomarker samples are collected during the study. The goal of the REVEL study is to demonstrate that ramucirumab in combination with docetaxel improves overall survival of patients with NSCLC with progressive disease after first-line therapy, and to advance our knowledge of the role of angiogenesis blockade in patients with NSCLC by identifying patients who are likely to experience maximum benefit based on extensive clinical biomarker correlative analysis.

8001 Background: Rociletinib is an oral inhibitor of mutant EGFR, including the T790M resistance mutation. We reported robust activity in T790M positive pts identified by tumor genotyping treated a...

Contexte R est un anticorps monoclonal humain IgG1 ciblant le domaine extracellulaire du VEGFR-2. L’etude REVEL a evalue l’efficacite et la tolerance de R + D vs P + D en traitement de seconde ligne des CBNPC de stade IV apres un traitement a base de sels de platine. Methodes Les points ayant un CBNPC non-epidermoide ou epidermoide (stratifies par sexe, region, PS, et traitement de maintenance anterieur) ont ete randomises (1:1) entre D 75 mg/m2 et R 10 mg/kg ou P/(3 semaines) jusqu’a progression, toxicite inacceptable ou deces. Le critere principal de jugement etait la survie globale (SG). Les criteres secondaires incluaient la survie sans progression (SSP), le taux de reponse objective (RO), la tolerance et la qualite de vie (QdV). L’analyse primaire de la QdV a porte sur le temps jusqu’a deterioration du score de symptomes (Lung Cancer Symptom Scale). Resultats Mille deux-cent cinquante-trois points (26,2 % epidermoides) ont ete randomises (R + D = 628 ; D = 625). Les caracteristiques des points etaient equilibrees entre les bras. Le taux de RO est de 22,9 % pour R + D vs 13,6 % pour D (p Conclusions L’adjonction du R au D ameliore significativement le taux de RO, la SSP et la SG par rapport au D en traitement de seconde ligne des CBNPC de stade IV.

More than half of the nascent B cells in humans initially express autoreactive antibodies. However, most of these autoantibodies are removed from the repertoire at two checkpoints before maturation into naive B cells. A third checkpoint excludes remaining autoantibodies from the antigen-experienced IgM(+) memory B cell pool. Nevertheless, low-affinity self-reactive antibodies are frequently found in the serum of normal humans. To determine the source of these antibodies, we cloned and expressed antibodies from circulating human IgG(+) memory B cells. Surprisingly, we found that self-reactive antibodies including anti-nuclear antibodies were frequently expressed by IgG(+) memory B cells in healthy donors. Most of these antibodies were created de novo by somatic hypermutation during the transition between mature naive and IgG(+) memory B cells. We conclude that deregulation of self-reactive IgG(+) memory B cells may be associated with autoimmunity.

Antibodies are protective effector molecules in the body's immune defense against pathogens. However, if directed against the body's own tissues or organs, antibodies can also play a role in the pathogenesis of autoimmune disease. Here, we discuss our data on how autoreactive antibodies are regulated in healthy humans and how a failure to establish self-tolerance during early B-cell development in patients with systemic lupus erythematosus may predispose to the development of this autoimmune disease.

During B lymphocyte development, antibodies are assembled by random gene segment reassortment to produce a vast number of specificities. A potential disadvantage of this process is that some of the antibodies produced are self-reactive. We determined the prevalence of self-reactive antibody formation and its regulation in human B cells. A majority (55 to 75%) of all antibodies expressed by early immature B cells displayed self-reactivity, including polyreactive and anti-nuclear specificities. Most of these autoantibodies were removed from the population at two discrete checkpoints during B cell development. Inefficient checkpoint regulation would lead to substantial increases in circulating autoantibodies.

Background VEGF-mediated angiogenesis contributes to NSCLC pathogenesis. RAM is a recombinant human mAb that binds the extracellular domain of the vascular endothelial growth factor receptor-2 (VEGFR-2) and inhibits cancer growth in diverse preclinical models. Methods Pts with advanced NSCLC (Stage IIIb not suitable for locoregional therapy or Stage IV) were eligible. Squamous histology and treated brain metastases were allowed. Exclusion criteria included prior bevacizumab, blood vessel invasion, intratumor cavitation, and recent gross hemoptysis. Pts received RAM 10 mg/kg, paclitaxel 200 mg/m2, and carboplatin AUC = 6 on Day 1 of a 3-week cycle for up to 6 cycles, followed by maintenance RAM. The primary endpoint was PFS at 6 months (m); secondary/exploratory endpoints were safety, ORR, OS rate at 1 year, PK/PD profiles, and immunogenicity. Results 40 pts were treated (15M:25F; median age 60; 39 nonsquamous / 1 squamous); all have discontinued. 39 pts were evaluable for response. 22 of 40 treated pts had an objective response (1 CR, 21 PR; ORR = 55%). 14 pts had a best response of SD. Median PFS was 7.85 m (95% CI: 5.49 m-9.86 m), and the PFS rate at 6 m was 62.5% (90% CI: 48.3%-75.3%); the 1-year survival rate was 74.6% (95% CI: 57.9%-85.4%). 34 of 40 pts (85%) reported an AE at least possibly related to RAM; the most common related AEs were fatigue (53%), peripheral neuropathy (33%), nausea (28%), myalgia (23%), and epistaxis (23%). Related AEs of Gr ≥ 3 were reported for 15 pts; the most common were neutropenia (5 pts), thrombocytopenia (4 pts), fatigue, febrile neutropenia (3 pts each), peripheral neuropathy and pulmonary embolism (2 pts each). There were 5 pts with a total of 6 Gr 4 related events: febrile neutropenia, pulmonary embolism (2 pts each), neutropenia and thrombocytopenia (1 pt each). Conclusions RAM in combination with paclitaxel and carboplatin shows promising efficacy based on the overall disease control rate (CR + PR + SD) reaching 90% and PFS rate at 6 m of 62.5%, and is well tolerated by patients with NSCLC. Disclosure D.R. Camidge: I have received research funding from Eli Lilly and Company and honoraria from ImClone Systems. R.C. Doebele: Research Funding: ImClone Systems, Eli Lilly & Co., Pfizer Inc. Honoraria: Boehringer Ingelheim, Abbott Laboratories, Pfizer Inc Stock: Ariad ( M. Ballas: I now have an employment position at Bristol Myers Squibb (BMS), own T. Jahan: I have received additional research funding from Eli Lilly & Co. for other trials, as well as research funding from Morphotek, Pfizer, and Genentech. I have no speaker or consultant income to disclose. S. Yurasov: Employed by ImClone/Eli Lilly; own Lilly stock. All other authors have declared no conflicts of interest.

Aim: RAM + DTX significantly improved overall survival and progression-free survival in pts with locally advanced or metastatic NSCLC with progression after platinum based chemotherapy. QoL data was obtained. Methods: Lung cancer symptom scale (LCSS) includes 6 symptom questions (loss of appetite, fatigue, cough, dyspnea, hemoptysis, pain) and 3 global items (symptom distress, difficulties with daily activities, global QoL) measured on a 0-100 mm scale, with higher scores representing greater symptom burden. LCSS and ECOG performance status (PS) data were collected at baseline (BL), every cycle, and at 30-day follow up (FU). LCSS total score and average symptom burden index (ASBI) were calculated. The primary prespecified analysis was time to deterioration (TtD) of the LCSS defined as increase from BL by ≥15 mm using the Kaplan-Meier method. TtD to PS ≥ 2 was also analysed. Results: Of the 1253 pts randomized to receive RAM + DTX or PL + DTX, 66.6% were male, median age was 62, and 67.4% had PS1. Pt compliance with LCSS was approximately 75% and balanced across both arms. The mean BL LCSS total score was 27.3 (SD 17.08) and 29.6 (SD 17.59) on RAM + DTX and PL + DTX, respectively. During treatment, the symptom burden appeared similar between treatment arms. At 30-day FU, mean total LCSS score was 32.0 (SD 19.03) and 32.5 (SD 19.87) on RAM + DTX and PL + DTX, respectively, reflecting a similar increase in symptom burden for both arms (mean increase of 5.4 and 6.0 from BL, respectively). The TtD for all LCSS scores was similar between treatment arms. Stratified HRs (95% CI) for LCSS total score and ASBI were HR = 0.99 (0.81, 1.22), p = 0.932 and HR = 0.93 (0.75, 1.15), p = 0.514 with approximately 70% of pts censored. TtD to PS ≥ 2 was similar between treatment arms (HR = 1.03; [95% CI: 0.85, 1.26], p = 0.742) with approximately two-thirds of the pts censored. Conclusions: In addition to the improvement of clinical outcomes demonstrated in REVEL, the primary QoL analyses suggest that there was no detriment in QoL and pt functioning by adding RAM to DTX second line chemotherapy. Disclosure: K. Park: Advisor - AVEO, Astellas, BI, Astra Zeneca, Clovis, Daiichi Sankyo, Eli Lilly, Roche; M. Thomas: I Receive speakers and AD-Board Honoraria from Lilly Roche BMS AD-Board Honoraria from AstraZeneca Novartis Pierre Fabre; S. Yurasov: I am a full time employee of Ely Lilly & Co. the Sponsor of this clinical study; A. Zimmermann: I am an employee of Eli Lilly and do own stock in Lilly; G. Cuyun Carter: Employee and stockholder of Eli Lilly and Company; M. Reck: Member of Adboard (compensated): Hoffmann-La Roche, Lilly, BMS, Pfizer, Novartis, Boehringer-Ingelheim, AstraZeneca Honoraria for lectures: Hoffmann-La Roche Lilly, BMS, Pfizer, Novartis, Boehringer-Ingelheim, AstraZeneca; M. Perol: Advisory Board for Roche. All other authors have declared no conflicts of interest.

LBA8006^ Background: RAM is a human IgG1 monoclonal antibody that targets the extracellular domain of VEGFR-2. The REVEL study evaluated the efficacy and safety of RAM+DOC vs. PL+DOC (DOC) in patients (pts) with stage IV nonsquamous (NSQ) and squamous (SQ) NSCLC after platinum-based therapy. Methods: Pts with NSQ and SQ stage IV NSCLC were randomized 1:1 (stratified by sex, region, ECOG PS, and prior maintenance therapy) to receive DOC 75 mg/m2 in combination with either RAM 10 mg/kg or PL on day 1 of a 21-day cycle until disease progression, unacceptable toxicity, or death. The primary endpoint was overall survival (OS). Secondary efficacy endpoints included progression-free survival (PFS), and objective response rate (ORR). Results: Between Dec 2010 and Feb 2013, 1,253 pts (26.2% SQ) were randomized (RAM+DOC: 628; DOC: 625). Pt characteristics were balanced between arms. ORR was 22.9% for RAM+DOC and 13.6% for DOC (P5% of pts on RAM+DOC were neutropenia (34.9% vs. 28.0%), febrile neutropenia (15.9% vs. 10.0%), fatigue (11.3% vs. 8.1%), leukopenia (8.5% vs. 7.6%), hypertension (5.4% vs. 1.9%), and pneumonia (5.1% vs. 5.8%). Grade 5 AEs were comparable between arms (5.4% vs. 5.8%), as was pulmonary hemorrhage (any grade; all pts: 2.1% vs. 1.6%; SQ pts: 3.8% vs. 2.4%). Conclusions: REVEL demonstrated a statistically significant improvement in ORR, PFS, and OS for RAM+DOC vs DOC in NSCLC pts with stage IV NSCLC as second-line treatment after platinum-based therapy. Benefits were similar in NSQ and SQ pts, and no unexpected AEs were identified. Clinical trial information: NCT01168973.

To generate an in vivo system for investigating the postintegration phase of HIV-1 replication, mouse lines transgenic for a full-length infectious proviral clone of a monocyte-tropic HIV-1 isolate, HIV-1JR-CSF, were constructed. Leukocytes from two independent JR-CSF transgenic mouse lines produced HIV-1 that infected human PBMCs. Plasma viremia was detected in these mice at levels (mean, >60,000 HIV RNA copies/ml) comparable to those reported for HIV-1-infected individuals. The levels of HIV RNA in these mice increased several-fold after either treatment with the superantigen Staphylococcus enterotoxin B or infection with Mycobacterium tuberculosis. Thus, a provirus encoding a monocyte-tropic HIV-1 strain under the control of its LTR expressed as a transgene in mice can proceed through the postintegration replication phase and produce infectious virus. In addition, the presence of plasma viremia that can be monitored by measuring plasma HIV-1 RNA levels permits these mice to be used to study the impact of different interventions on modulating in vivo HIV-1 production. Therefore, these mice provide a novel manipulable system to investigate the in vivo regulation of HIV-1 production by factors that activate the immune system. Furthermore, this murine system should be useful in delineating the role of human-specific factors in modulating HIV-1 replication and investigating the in vivo therapeutic efficacy of agents that target the postintegration stages of HIV-1 replication.

Modifications that we introduced into the implantation of human fetal thymus and liver into SCID mice (thy/liv-SCID-hu mice) markedly increased the population of human T cells and monocytes present in the peripheral blood and peripheral lymphoid compartment of these mice. As a result, the modified thy/liv-SCID-hu mice developed disseminated HIV infection after intraimplant or i.p. inoculation. After chronic HIV infection of these mice, depletion of the peripheral human T cells was observed as reported in HIV-infected individuals. In addition, these mice also developed plasma viremia after infection with HIV. The peripheral blood mononuclear cells were responsive to in-vivo cytokine regulation as evidenced by induction of human IFN-gamma gene expression by human IL-12 and inhibition by human IL-10. Acute treatment with human IL-10 but not with human IL-12 inhibited the development of plasma viremia and HIV infection in thy/liv-SCID-hu mice inoculated with HIV-1(59), a clinical isolate. SCID mice transplanted with cultured human fetal bone marrow displayed significant engraftment of the mouse bone marrow with human precursor cells and population of the peripheral blood with human B cells and monocytes. The peripheral blood of these bone marrow-transplanted SCID mice also became populated with human T cells after they were implanted with human thymic tissue due to migration of human precursor cells from the mouse bone marrow to the implanted human thymus. Thus, these modified SCID-hu mice should prove to be a valuable in-vivo model for studying the immunopathogenesis of HIV infection and for examining the in-vivo efficacy of immunomodulatory, drug and gene therapy in modifying HIV infection.

Background Vascular endothelial growth factor (VEGF)-mediated angiogenesis plays an important role in NSCLC pathogenesis. RAM is a fully human IgG1 monoclonal antibody that inhibits VEGF receptor-2 (VEGFR-2) binding and signaling. This study investigates RAM in combination with first-line platinum-based chemotherapy in advanced NSCLC. Methods NSQ pts with Stage IV NSCLC, ECOG PS ≤ 2, adequate hematologic, hepatic and renal function were randomized to either Arm A: pemetrexed + carboplatin/cisplatin or Arm B: RAM + pemetrexed + carboplatin/cisplatin, once every 3 weeks. The primary analysis will be when 103 progression-free survival (PFS) events are observed in NSQ pts. This pre-planned interim analysis was performed when 61 NSQ PFS events were observed. Other interim endpoints: objective response rate, disease control rate (DCR), and safety. Results Arm A (n = 71) median (medn) age 64, 63% male (M), 37% female (F), ECOG PS 0-1 / 2 (91.6% / 5.6%). Arm B (n = 69) medn age 64, 52% M, 48% F, ECOG PS 0-1 / 2 (89.9% / 7.2%). Interim efficacy analyses Arm A (N = 71) n (%) Arm B (N = 69) n (%) PFS Events Censored Median (months) 90% CI 37 (52) 34 (48) 4.3 (3.8, 5.7) 24 (35) 45 (65) 6.3 (5.7, -) Best Response PR SD DCR (SD + PR) 26 (37) 25 (35) 51 (72) 30 (44) 30 (44) 60 (88) Nonhematologic adverse events (AEs) were fatigue (61%; 17% Grade[G]3), nausea (55%; 7% G3), vomiting (36%; 4% G3), constipation (30%; 1% G3), hypertension (HTN) (6%; 1% G3), proteinuria (4%; 0 G3), on Arm A; fatigue (63%; 12% G3), nausea (51%; 10% G3), vomiting (33%; 8% G3), constipation (27%; 0 G3), HTN (19%; 10% G3), proteinuria (5%; 0 G3) on Arm B. Hematologic AEs were anemia (A) (55%; 16% G3), neutropenia (N) (23%; 16% G3), thrombocytopenia (T) (23%; 12% G3) on Arm A; A (39%; 8% G3), N (33%; 13% G3), T (31%; 15% G3) on Arm B. Conclusions Based on interim analyses of PFS and acceptable tolerability and safety, RAM may provide clinical benefit in combination with first-line platinum-based chemotherapy in NSQ NSCLC. Enrollment of pts in squamous Arms C and D is ongoing. Disclosure R. Doebele: Research funding: ImClone Systems, Eli Lilly & Co., Pfizer Inc. Honoraria: Boehringer Ingelheim, Abbott Laboratories, Pfizer Inc. Stock: Ariad ( M. Reck: Honoraria for Lectures: Lilly, Hoffmann-La Roche, AstraZeneca, Daiichi-Sankyo Advisory Board (compensated): Lilly, Hoffmann-La Roche, AstraZeneca, Daiichi-Sankyo, Pfizer, Merck, BMS. S. Verma: Advisory Board and honoraria from Eli Lilly. S. Yurasov: I am employed by Eli Lilly and own Lilly stock. D.R. Camidge: Advisory role and honoraria: ImClone Reserach Funding: Eli Lilly. All other authors have declared no conflicts of interest.

R1507 is a fully human monoclonal antibody that binds the IGF-1 receptor (IGF1R) and blocks IGF1R-mediated signal transduction. A phase 1 trial of weekly R1507 in adults did not define a maximum tolerated dose (MTD), and dose-limiting toxicity (DLT) was not observed. This pediatric phase 1 trial of R1507 was designed to identify a dose that achieves a mean area under the concentration x time curve (AUC0–7d) >85% of the mean AUC0–7d (18,700 mcg•h/mL) in adults at the recommended phase 2 dose (RPTD) of 9 mg/kg weekly. The design can define an MTD if DLT occurs. Patients (pts) age >2 and 6 years. Dosing based on body surface area may be preferable for children Single Dose PK Parameter Mean (%CV) Age group Cmax (mcg/mL) CL (mL/day/kg) AUC0–7d (mcg·h/mL) Ctrough, steady state (day 35) (mcg/mL) Simulated AUC0–7d (mcg·h/mL)* 2–6 y 222 (20) 7.1 (15) 17,100 (13) 196 24,800 (n=4) (N/A n=1) 7–11 y 253 (30) 7.0 (27) 20,900 (30) 208 23,000 (n=6) (39; n=5) 12–17 y 293 (16) 5.5 (28) 25,000 (16) 248 24,400 (n=6) (39; n=5) * Simulated AUC0–7d for dosing with 300 mg/m2 Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C112.

Treatment with protease inhibitors alone or in combination with inhibitors of reverse transcriptase potently suppresses levels of human immunodeficiency virus (HIV) RNA in plasma and thereby may significantly delay the progression of HIV-mediated disease. To investigate the effect of treatment with the protease inhibitor saquinavir on HIV replication in the lymphoid tissues, we used a SCID-hu mouse model that we developed, in which human thymic and liver tissues (hu-thy/liv) were implanted under both kidney capsules in SCID mice (thy/liv-SCID-hu mice). These mice are populated in the periphery with large numbers of human T cells and develop disseminated HIV infection after intraimplant injection. thy/liv-SCID-hu mice with established HIV infection that were treated for 1 month with saquinavir had a significantly lower viral load present in the implanted hu-thy/liv and mouse spleen than did the untreated HIV-infected thy/liv-SCID-hu mice. To examine the capacity of acute treatment with saquinavir to prevent HIV infection, some thy/liv-SCID-hu mice were inoculated with HIV and then immediately started on saquinavir. Although treated mice had markedly lower viral loads in the thy/liv implants and spleens, HIV infection was not completely prevented. Thus, the effect of antiviral therapy on HIV infection in the major site of HIV replication, the lymphoid tissues, can be readily evaluated in our thy/liv-SCID-hu mice. These mice should prove to be a useful model for determining the in vivo effectiveness of different therapeutic interventions on acute and chronic HIV infection.