Pembrolizumab plus chemotherapy in Japanese patients with metastatic squamous non-small-cell lung cancer in KEYNOTE-407

The global phase III KEYNOTE-407 (NCT02775435) trial showed that pembrolizumab plus chemotherapy prolonged overall and progression-free survival (OS/PFS) versus placebo plus chemotherapy in patients with metastatic squamous non-small-cell lung cancer (NSCLC). We present outcomes of patients from Japan enrolled in KEYNOTE-407. Patients were randomized 1:1 to receive pembrolizumab 200 mg or placebo with paclitaxel 200 mg/m² every 3 weeks (Q3W) or nab-paclitaxel 100 mg/m² (weekly) plus carboplatin area under the concentration-time curve of 6 mg/mL/min Q3W for four cycles, followed by pembrolizumab or placebo Q3W for a total of 35 cycles. Primary end-points were OS and PFS per RECIST version 1.1 by blinded independent central review. Fifty patients were randomized at Japanese sites (pembrolizumab plus chemotherapy, n = 22; placebo plus chemotherapy, n = 28). Median follow-up time at data cut-off (May 9, 2019) was 15.1 (range, 0.5-24.0) months. Median OS (95% confidence interval [CI]) was 17.3 (12.5-not reached) versus 11.0 (8.6-19.5) months in the pembrolizumab plus chemotherapy versus placebo plus chemotherapy group (hazard ratio [HR] 0.56; 95% CI, 0.27-1.15). Median PFS (95% CI) was 8.3 (6.1-13.0) versus 7.2 (3.9-8.8) months (HR 0.65; 95% CI, 0.35-1.23). Grade 3-5 adverse events (AEs) occurred in 86% and 75% of patients, respectively. There were three fatal AEs, two of which were treatment-related (one from each treatment group, pneumonitis and pulmonary hemorrhage). Efficacy and safety outcomes were consistent with the global study and support the use of pembrolizumab plus chemotherapy in Japanese patients with metastatic squamous NSCLC.

Pembrolizumab Plus Chemotherapy in Squamous Non-Small-Cell Lung Cancer: 5-Year Update of the Phase III KEYNOTE-407 Study

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.We report 5-year efficacy and safety outcomes from the phase III KEYNOTE-407 study (ClinicalTrials.gov identifier: NCT02775435). Eligible patients with previously untreated, metastatic squamous non-small-cell lung cancer (NSCLC) were randomly assigned 1:1 to pembrolizumab 200 mg or placebo plus carboplatin and paclitaxel/nab-paclitaxel once every 3 weeks for four cycles, followed by pembrolizumab or placebo for up to 35 cycles. Primary end points were overall survival (OS) and progression-free survival (PFS) per RECIST version 1.1 by blinded independent central review (BICR). Five hundred fifty-nine patients were randomly assigned in the intention-to-treat population (pembrolizumab plus chemotherapy, n = 278; placebo plus chemotherapy, n = 281). The median time from random assignment to data cutoff was 56.9 (range, 49.9-66.2) months. OS and PFS were improved with pembrolizumab plus chemotherapy versus placebo plus chemotherapy (hazard ratio [95% CI], 0.71 [0.59 to 0.85] and 0.62 [0.52 to 0.74]), with 5-year OS rates of 18.4% versus 9.7%, respectively. Toxicity was manageable. Among 55 patients who completed 35 cycles of pembrolizumab, the objective response rate was 90.9% and the 3-year OS rate after completion of 35 cycles (approximately 5 years after random assignment) was 69.5%. Pembrolizumab plus chemotherapy maintained an OS and PFS benefit versus placebo plus chemotherapy in previously untreated, metastatic squamous NSCLC and is a standard-of-care first-line treatment option for metastatic squamous NSCLC regardless of programmed death ligand 1 expression.

Pembrolizumab Plus Pemetrexed and Platinum in Nonsquamous Non-Small-Cell Lung Cancer: 5-Year Outcomes From the Phase 3 KEYNOTE-189 Study

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically on the based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.We present 5-year outcomes from the phase 3 KEYNOTE-189 study (ClinicalTrials.gov identifier: NCT02578680). Eligible patients with previously untreated metastatic nonsquamous non-small-cell lung cancer without EGFR/ALK alterations were randomly assigned 2:1 to pembrolizumab 200 mg or placebo once every 3 weeks for up to 35 cycles with pemetrexed and investigator's choice of carboplatin/cisplatin for four cycles, followed by maintenance pemetrexed until disease progression or unacceptable toxicity. Primary end points were overall survival (OS) and progression-free survival (PFS). Among 616 randomly assigned patients (n = 410, pembrolizumab plus pemetrexed-platinum; n = 206, placebo plus pemetrexed-platinum), median time from random assignment to data cutoff (March 8, 2022) was 64.6 (range, 60.1-72.4) months. Hazard ratio (95% CI) for OS was 0.60 (0.50 to 0.72) and PFS was 0.50 (0.42 to 0.60) for pembrolizumab plus platinum-pemetrexed versus placebo plus platinum-pemetrexed. 5-year OS rates were 19.4% versus 11.3%. Toxicity was manageable. Among 57 patients who completed 35 cycles of pembrolizumab, objective response rate was 86.0% and 3-year OS rate after completing 35 cycles (approximately 5 years after random assignment) was 71.9%. Pembrolizumab plus pemetrexed-platinum maintained OS and PFS benefits versus placebo plus pemetrexed-platinum, regardless of programmed cell death ligand-1 expression. These data continue to support pembrolizumab plus pemetrexed-platinum as a standard of care in previously untreated metastatic non-small-cell lung cancer without EGFR/ALK alterations.

Abstract CT561: KeyVibe-003: Randomized, double-blind, phase 3 study of first-line pembrolizumab with and without vibostolimab (anti-TIGIT) in patients with PD-L1-positive metastatic NSCLC

Background: Vibostolimab (MK-7684) is a humanized monoclonal antibody (mAb) that binds to the T-cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT), blocking the interaction between TIGIT and its ligands, CD112 and CD155. Pembrolizumab, an anti-PD-1 mAb, significantly improves OS versus chemotherapy in patients with PD-L1-positive advanced non-small-cell lung cancer (NSCLC). In the first-in-human study (NCT02964013), the combination of vibostolimab plus pembrolizumab had a manageable safety profile and showed promising antitumor activity in patients with advanced NSCLC naive to anti-PD-(L)1 therapy; ORR was 31% and 25% in patients with PD-L1 tumor proportion score (TPS) ≥1% and less than 1%, respectively. The current phase 3 study (KeyVibe-003; ClinicalTrials.gov, NCT04738487) is comparing first-line treatment with MK-7684A, a co-formulation of vibostolimab plus pembrolizumab, versus pembrolizumab monotherapy in patients with PD-L1-positive metastatic NSCLC.

Methods: This randomized, multicenter, double-blind study is enrolling adults with pathologically confirmed, previously untreated, metastatic NSCLC with PD-L1 TPS ≥1% (centrally confirmed). Patients must have measurable disease per RECIST v1.1, an ECOG PS of 0-1, have no EGFR mutations or ALK or ROS1 gene rearrangements, and have no active or untreated CNS metastases. Patients are randomized 1:1 to receive intravenous treatment with vibostolimab 200 mg plus pembrolizumab 200 mg Q3W or pembrolizumab 200 mg Q3W for up to 35 cycles (approximately 2 years) or until PD, unacceptable AEs, intercurrent illness, or investigator decision. Patients who stop treatment after a CR or after completing 35 cycles and subsequently have PD can receive up to 17 additional cycles (approximately 1 year) of their randomized therapy. Randomization is stratified by ECOG PS (0 vs 1), PD-L1 TPS (1%-49% vs ≥50%), and region of enrollment (East Asia vs non-East Asia). The dual primary endpoints are PFS, per RECIST v1.1 by blinded independent central review (BICR), and OS. Secondary endpoints include ORR and DOR per RECIST v1.1 by BICR, patient-reported outcomes, and safety. Radiographic imaging occurs at baseline, Q9W from randomization through week 54, and then Q12W until PD, the start of new anticancer treatment, withdrawal of consent, or death. Health-related quality of life is assessed using validated patient-reported outcome instruments including the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30. AEs are graded according to National Cancer Institute Common Terminology Criteria for Adverse Events v5.0. Enrollment began in April of 2021, and is ongoing at 83 sites in 15 countries.

Results: N/A

Conclusions: N/A

Citation Format: Byoung Chul Cho, Rosalyn A. Juergens, Ying Cheng, Gilberto de Castro Jr., Mustafa Erman, Jessica R. Bauman, Toshiaki Takahashi, Paul Schwarzenberger, Chengxiang Li, M. Catherine Pietanza, James Chih-Hsin Yang. KeyVibe-003: Randomized, double-blind, phase 3 study of first-line pembrolizumab with and without vibostolimab (anti-TIGIT) in patients with PD-L1-positive metastatic NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT561.

Circulating Immune Cell and Outcome Analysis from the Phase II Study of PD-L1 Blockade with Durvalumab for Newly Diagnosed and Recurrent Glioblastoma

PURPOSE

PD-L1 is upregulated in glioblastoma and supports immunosuppression. We evaluated PD-L1 blockade with durvalumab among glioblastoma cohorts and investigated potential biomarkers.

PATIENTS AND METHODS

MGMT unmethylated newly diagnosed patients received radiotherapy plus durvalumab (cohort A; n = 40). Bevacizumab-naïve, recurrent patients received durvalumab alone (cohort B; n = 31) or in combination with standard bevacizumab (cohort B2; n = 33) or low-dose bevacizumab (cohort B3; n = 33). Bevacizumab-refractory patients received durvalumab plus bevacizumab (cohort C; n = 22). Primary endpoints were: OS-12 (A), PFS-6 (B, B2, B3), and OS-6 (C). Exploratory biomarkers included: a systematic, quantitative, and phenotypic evaluation of circulating immune cells; tumor mutational burden (TMB); and tumor immune activation signature (IAS).

RESULTS

No cohort achieved the primary efficacy endpoint. Outcome was comparable among recurrent, bevacizumab-naïve cohorts. No unexpected toxicities were observed. A widespread reduction of effector immune cell subsets was noted among recurrent patients compared with newly diagnosed patients that was partially due to dexamethasone use. A trend of increased CD8+Ki67+ T cells at day 15 was noted among patients who achieved the primary endpoint and were not on dexamethasone. Neither TMB nor IAS predicted outcome.

CONCLUSIONS

Patients with recurrent glioblastoma have markedly lower baseline levels of multiple circulating immune cell subsets compared with newly diagnosed patients. An early increase in systemic Ki67+CD8+ cells may warrant further evaluation as a potential biomarker of therapeutic benefit among patients with glioblastoma undergoing checkpoint therapy. Dexamethasone decreased immune cell subsets. PD-L1 blockade and combination with standard or reduced dose bevacizumab was ineffective.

337 Intratumoral immune therapy for recurrent breast cancer with polyICLC, and tremelimumab combined with systemic durvalumab

Background

Intratumoral (IT) cancer therapies may enhance T cell activation and tumor infiltration when combined with systemic checkpoint blockade. This approach may improve treatment of advanced breast cancer, which is commonly resistant to immune therapy.

Methods

A multicenter basket-style trial (NCT02643303) was performed in patients with advanced solid tumors, who received polyICLC IT 1mg x 6, then intramuscular (IM) x 3, combined with intravenous (IV) durvalumab 1500 mg q4W. Most were assigned to cohorts also receiving tremelimumab: 10 mg IT or 75 mg IV. Goals were to assess tolerability and clinical activity. Treated tumors were evaluated for immune infiltrates on days (d) 0, 15, and 29 by multiparameter immunofluorescence histology. A strong signal for clinical response was in breast cancer patients; thus, an expansion cohort was enrolled. We report analysis of that breast cancer subgroup.

Results

Nineteen participants with treatment-refractory recurrent breast cancer with median 4 prior lines of therapy were enrolled and treated with IV durvalumab and IT/IM polyICLC. Seventeen also received tremelimumab (15 IT, 2 IV). Common treatment-related AEs were fatigue, injection site pain, and chills. There was one dose-limiting toxicity in a participant who received tremelimumab IV, and died with severe hyponatremia (DLT) and progressive disease. Objective clinical responses (1 complete; 4 partial (1 unconfirmed)) were observed in 5 (26%), including 2/9 patients with triple-negative breast cancer (TNBC) and 3/10 with non-TNBC. Median OS was longer for those with CR, PR, or SD (not reached) vs. those with PD or not evaluable (5 months): two responders remain alive at 34+ and 40+ months. In injected tumors, there were significant increases from d0 to d29 in numbers/mm2 of CD8+ T cells, CD20+ B cells, mature dendritic cells (DC), macrophages, and CD56+ NK cells, and in CD8+ cells with antigen-experience (CD45RO), cytotoxic function (granzyme B), activation (ICOS1), or proliferation (Ki67). CD8+ cells expressing LAG3 and TIM3 increased, as did PDL1+ tumor cells and stromal cells. There were no differences in cells expressing IDO, ARG1, CD39, or CD73. Among patients with objective response, vs. all others, proportions of intratumoral CD8+ cells expressing Ki67 increased (p < 0.04).

Conclusions

IT tremelimumab and polyICLC plus systemic durvalumab is safe and has clinical activity in patients with advanced TNBC and non-TNBC. The therapy enhances intratumoral immune effectors and markers of T cell function in hypothesis-generating data that warrant confirmatory studies. Clinical response was associated with longer survival and increased CD8 T cell proliferation.

Trial Registration

NCT02643303

Ethics Approval

The study has been performed with approval of the institutional review boards of each participating institution (Roswell Park Cancer Institute: STUDY 00000121/I291016; Mount Sinai School of Medicine: IRB-17-01692; University of Virginia: IRB # 19276; Cleveland Clinic: 18-694; Toledo: 300176; Dartmouth: STUDY00031630; Emory: IRB00099445). All participants give informed consent before enrolling and participating. The study was also performed with approval from the FDA

Pembrolizumab Plus Chemotherapy for Chinese Patients With Metastatic Squamous NSCLC in KEYNOTE-407

Introduction

Pembrolizumab plus chemotherapy significantly improved survival outcomes versus placebo plus chemotherapy in patients with previously untreated metastatic squamous NSCLC in the randomized, double-blind, phase 3 KEYNOTE-407 study. We present the results of Chinese patients enrolled in the KEYNOTE-407 global and China extension studies.

Methods

Patients enrolled from mainland China in the KEYNOTE-407 global (NCT02775435) and China extension studies (NCT03875092) were randomized 1:1 to 35 cycles of pembrolizumab or placebo plus four cycles of carboplatin and paclitaxel or nab-paclitaxel. Dual primary end points were overall survival (OS) and progression-free survival (PFS) (based on the Response Evaluation Criteria in Solid Tumors version 1.1 by blinded independent central review).

Results

A total of 125 patients were randomized (pembrolizumab-chemotherapy, n = 65; placebo-chemotherapy, n = 60). As of September 30, 2020, median (range) study follow-up was 28.1 (25.1‒40.9) months. Pembrolizumab-chemotherapy improved OS (hazard ratio [HR] = 0.44, 95% confidence interval [CI]: 0.28-0.70) and PFS (HR = 0.35, 95% CI: 0.24-0.52) versus placebo-chemotherapy. Two-year OS and PFS rates for pembrolizumab-chemotherapy versus placebo-chemotherapy were 56.9% versus 31.7% and 24.2% versus 3.3%, respectively. Treatment-related grade 3 to 5 adverse events occurred in 81.5% and 81.7%, respectively. Relative to baseline, pembrolizumab-chemotherapy improved global health status/quality of life scores at week 18 versus placebo-chemotherapy (difference in least squares means = 7.6, 95% CI: 1.5-13.7) and prolonged time to deterioration in cough, chest pain, or dyspnea (HR = 0.50, 95% CI: 0.28-0.89).

Conclusions

Pembrolizumab-chemotherapy prolonged survival versus placebo-chemotherapy with manageable toxicity and preserved or improved health-related quality of life in Chinese patients with metastatic squamous NSCLC. These findings support pembrolizumab-chemotherapy as first-line therapy in this population.

Phase I/II study to evaluate systemic durvalumab + intraperitoneal (IP) ONCOS-102 in patients with peritoneal disease who have epithelial ovarian (OC) or metastatic colorectal cancer (CRC): Interim phase I clinical and translational results

3017

Background: Metastasis to the peritoneal cavity is associated with end-stage disease in many cancers, including OC and CRC, both of which exhibit poor responses to checkpoint inhibitors. Locoregional treatment with oncolytic viruses may be used to improve the efficacy of checkpoint inhibitors at both treated and distant tumor sites. This study evaluates the combination of IP-administered ONCOS-102, an oncolytic adenovirus encoding for granulocyte macrophage colony stimulating factor (GMCSF), with systemic durvalumab, an anti PD-L1 antibody, in patients with peritoneal disease who have histologically confirmed OC or metastatic CRC and have failed prior standard therapies. Methods: This ongoing Phase 1/2, open-label study (NCT02963831) evaluates safety and antitumor/biologic activity of durvalumab (1500 mg IV, every 4 weeks x 12) + ONCOS-102 (IP, weekly x 6); cyclophosphamide is given pre first ONCOS-102 dose. Phase 1 uses a 3+3 design to evaluate the ONCOS-102 dose (1 or 3 x 1011 VP) to be given with durvalumab. Phase 2 evaluates the activity of the combination using Simon’s 2-stage MINIMAX design. Safety, response rate by RECIST 1.1, and immunological effects in tumors were evaluated for Phase 1; the current abstract reports on the phase 1 results. Results: Enrollment opened 7 Sep 2017; data cutoff, 1 Nov 2019. There were 17 patients treated in Phase 1: 8 CRC, 9 ovarian; 94% female; median age, 56 [37-77] years; ECOG PS0, 47%; ECOG PS1, 53%. There were no DLTs. Grade 3 treatment-related AEs included hypokalemia (n = 2); anemia, myocarditis, increased GGT, and influenza like illness (n = 1 each). There were 4 deaths due to PD. One patient had durable confirmed partial response and remains on treatment > 1 year; 4 patients had stable disease as best overall response. Two patients remained on treatment at data cutoff. Analysis of pre- and on-treatment tumor biopsies revealed changes in the tumor-infiltrating immune cells and PD-L1 expression, including an increase in tumor-infiltrating CD8 T cells in 5 of 11 evaluable patients. Conclusions: Combination of durvalumab and IP ONCOS-102 was safe, and no DLTs were observed. Preliminary analyses demonstrate evidence of biologic and clinical activity. Phase 2 enrollment is ongoing. Clinical trial information: NCT02963831 .

A Prospective, Phase 1 Trial of Nivolumab, Ipilimumab, and Radiotherapy in Patients with Advanced Melanoma

PURPOSE

Preclinical data suggest that radiotherapy (RT) is beneficial in combination with immune checkpoint blockade. Clinical trials have explored RT with single-agent immune checkpoint blockade, but no trials have reported RT with the combination of nivolumab and ipilimumab.

PATIENTS AND METHODS

We conducted a phase 1 study of patients with stage IV melanoma receiving nivolumab and ipilimumab with two different dose-fractionation schemes of RT. Patients had at least one melanoma metastasis that would benefit from palliative RT and one metastasis that would not be irradiated. Nivolumab 1 mg/kg + ipilimumab 3 mg/kg and extracranial RT with a dose of 30 Gy in 10 fractions was administered in Cohort A, and then 27 Gy in 3 fractions was administered in Cohort B. The primary outcome was safety.

RESULTS

Twenty patients were treated (10 in each cohort). The rates of treatment-related grade 3-4 adverse events in Cohort A and B were 40% and 30%, respectively. There were no grade ≥3 adverse events attributed to RT. Patients responded to treatment outside of the irradiated volume (Cohort A 5/10; Cohort B 1/9). No evaluable patients had progression of irradiated metastases. Immunologic changes were seen in the peripheral blood with increases in T-cell receptor diversity in some responding patients.

CONCLUSIONS

RT with nivolumab and ipilimumab was safe compared with historical data of nivolumab and ipilimumab alone. Immunologic effects were observed in the peripheral blood. Randomized studies are ongoing to assess whether RT increases the efficacy of nivolumab and ipilimumab.

Phase II study to evaluate safety and efficacy of MEDI4736 (durvalumab) + radiotherapy in patients with newly diagnosed unmethylated MGMT glioblastoma (new unmeth GBM)

2032

Background: Durvalumab (durva), a human IgG1 monoclonal Ab against PD-L1, is FDA-approved for selected patients with bladder and non-small cell lung cancers. PD-L1 is expressed by some GBM tumors, while GBM infiltrating T lymphocytes often express PD-1. Radiation induced cell death releases tumor antigens and could potentiate anti-PD-(L)1 therapy. Methods: This ongoing Phase 2 open-label study (NCT02336165) evaluates the safety and efficacy of durva (10 mg/kg every 2 weeks) in 5 GBM cohorts. Results are presented for Cohort A, which evaluates durva + standard radiotherapy (RT, 60 Gy over 30 fractions) followed by durva monotherapy in patients with new unmeth GBM after maximum safe resection. The primary efficacy endpoint for Cohort A is overall survival at 12 months (OS12); secondary endpoints include safety/tolerability, tumor response rate, and progression-free survival (PFS). Historical benchmarks of median OS and OS12 for patients with new unmeth GBM following standard therapy are 12.7 months and 50%, respectively (EORTC 26981-22981/NCIC CE.3). Results: Median follow-up of 40 enrolled patients is 24.5 months (data cutoff = 05 Nov 2018). Baseline characteristics: male, 70%; median age, 57.0 [22 to 77] years; ECOG PS0, 60.0%; ECOG PS1, 40.0%; measurable disease, 80.0%; and dexamethasone use, 32.5%. Treatment-related adverse events with maximum CTCAE grade ≥ 3 occurred in 14 (35.0%) patients; the most common were asymptomatic increased lipase (n = 6) and increased amylase (n = 2). Twenty-four of 40 patients were alive at 12 months (Kaplan-Meier for OS12, 60.0% [90% CI: 46.1, 71.4]). Median OS was 15.1 (95% CI: 12.0, 18.4) months. As of 05 Nov 2018, 8 (20%) patients remain alive, with ongoing survival ranging from 15.7 to 34.9 months. Tumor immunocorrelative and systemic studies are pending. Conclusions: This is the first study report of anti-PD-L1 for new GBM. Durva was well tolerated when combined with RT and seemed to have efficacy among patients with new unmeth GBM. Further studies may be warranted. Clinical trial information: NCT02336165.

Abstract A006: Phase 1 study to evaluate the safety and tolerability of MEDI4736 (durvalumab, durva) + tremelimumab (treme) in patients with advanced solid tumors

Durvalumab (durva) is a human IgG1 monoclonal antibody (mAb) that blocks programmed cell death ligand-1 (PD-L1). Tremelimumab (treme) is a human IgG2 mAb inhibitor of cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4). Blocking these checkpoints can result in antitumor activity in some solid tumors. The targets for durva and treme are non-redundant, providing sound rationale for clinical testing of the combination.This is an ongoing phase 1, multicenter, open-label study (NCT01975831) with a dose escalation (3+3 design) and subsequent expansion phase. Patients with renal cell carcinoma (RCC), cervical (CC), colorectal (CRC), non-triple-negative breast (NTNBC), or ovarian (OC) cancer are included in the expansion phase. The protocol excludes patients who had prior exposure to anti-CTLA-4 or anti-PD-1/PD-L1 antibodies. Primary objectives are safety/tolerability and identification of maximum tolerated dose (MTD) of the combination. Secondary objectives include tumor response, progression-free survival (PFS), and overall survival (OS). The intent-to treat (ITT) analysis set includes all patients who received at least one dose of durva or treme and had the baseline and at least one post-baseline tumor assessment.As of 11 May 2018, 104 patients were treated (73.1% female; median age: 56 (30 to 80) years. Durva 1500 mg every 4 weeks (Q4W) X 12 and treme 75 mg Q4W X 4 was the regimen used for opening the expansion phase (n = 82 patients). The majority of treatment-related adverse events (TRAEs) for all patients were Grades 1 and 2. TRAEs ≥ Grade 3 were reported in 17 (16.3%) patients; the majority were diarrhea/colitis (n = 6) and abnormal liver function tests (n = 4) and responded to established treatment algorithms. There was 1 Grade 5 TRAE: multi-organ failure. Fifteen (14.4%) patients experienced TRAEs leading to treatment discontinuation; the majority were diarrhea/colitis (n = 6) and abnormal liver function tests (n = 5). No new toxicities were identified. Tumor response by immune-related Response Criteria (irRC) was assessed by tumor type in the ITT analysis set for all cohorts included in the expansion phase; the follow-up period was at least 12 months. Best overall responses (complete response (irCR), partial response (irPR) and stable disease (irSD)) are presented by tumor type. For OC (n = 27): irCR = 0, irPR = 2 (7.4%), irSD = 10 (37%); for CRC (n = 18): irCR = 1 (5.6%), irPR = 1 (5.6%), irSD = 2 (11.1%); for NTNBC (n = 16): irCR = 0, irPR = 1 (6.3%), irSD = 2 (12.5%); for RCC (n = 19): irCR = 0, irPR = 3 (15.8%), irSD = 11 (57.9%); and for CC (n = 16): irCR = 1 (6.3%), irPR = 3 (18.8%), irSD = 4 (25%) patients. PD-L1 status is not yet available. MSI status was collected retrospectively for patients with CRC; in this group, the patient with irPR had MSI-high status, and the MSI status of the patient with irCR is unknown. PFS and OS rates will be presented at the meeting. In conclusion, the durva and treme combination has a manageable safety profile, with evidence of clinical activity. These data support continued study of the combination therapy.

Citation Format: Margaret K. Callahan, Kunle Odunsi, Mario Sznol, John Nemunaitis, Patrick A. Ott, Patrick Dillon, Reva Schneider, Andrew Park, Paul Schwarzenberger, Toni Ricciardi, Mary Macri, Aileen Ryan, Ralph Venhaus, Jedd D. Wolchok. Phase 1 study to evaluate the safety and tolerability of MEDI4736 (durvalumab, durva) + tremelimumab (treme) in patients with advanced solid tumors [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A006.

Abstract B209: Phase 1/2 study of mRNA vaccine therapy + durvalumab (durva) ± tremelimumab (treme) in patients with metastatic non-small cell lung cancer (NSCLC)

Vaccine therapies stimulate the immune system to attack cancer cells (active immunotherapy), whereas checkpoint inhibitors block immune inhibition (passive immunotherapy). BI 1361849 (formerly CV9202) is a cancer vaccine comprising 6 mRNA constituents, each of which encodes for one of the non-small cell lung cancer (NSCLC) associated antigens: MUC1, survivin, NY-ESO-1, 5T4, MAGE-C2, and MAGE-C1. Durvalumab (durva) is a checkpoint inhibitor that blocks programmed cell death ligand-1 (PD-L1) binding to programmed cell death-1 (PD-1). Several PD-1 and PD-L1 blocking antibodies are approved for NSCLC. Tremelimumab (treme) is an anti-cytotoxic T-lymphocyte-associated antigen-4 (anti-CTLA-4) blocking antibody. Targeting both the CTLA-4 and PD-1 checkpoint pathways provides the potential for additive or synergistic effects. This study combines active and passive immunotherapies to determine if the addition of a mRNA vaccine, BI 1361849, can enhance the activity of checkpoint blockade. This ongoing phase 1/2, open-label study (NCT03164772) evaluates the safety and efficacy of BI 1361849 when administered with durva (Arm A) or durva + treme (Arm B) in patients with NSCLC. In Arm A, an initial dose evaluation phase follows a 3+3 design to confirm the dose of durva (full dose 1500 mg or de-escalated 750 mg, if needed) to be given with the vaccine. Arm B uses the dose established in Arm A, with the addition of 75 mg treme. In the expansion phase, 20 patients are treated in each arm. To aid in the evaluation of immune responses, there is an additional control group (n=10), in which patients receive the checkpoint inhibitor(s) only. Study treatment is administered over 12 cycles (28 days each). Durva (x 12 doses) and treme (x 4 doses, Arm B only) are administered intravenously every 28 days. The vaccine is administered as a total of 14 doses (of the 6 components) during the 12 cycles, using a device that provides a needle-free intradermal administration. The primary endpoint is assessment of safety and tolerability, including evaluation of dose-limiting toxicities. Secondary endpoints include progression-free survival and objective response rate at 8 and 24 weeks, disease control rate, response duration, and overall survival, with tumor response evaluated by RECIST 1.1 and immune-related RECIST. Exploratory objectives include effects on tumor microenvironment and evaluation of immune responses. Enrollment opened 20 December 2017. As of 27 June 2018, 2 patients are enrolled; enrollment is ongoing.

Citation Format: Joshua Sabari, Kristen Aufiero Ramirez, Paul Schwarzenberger, Toni Ricciardi, Mary Macri, Aileen Ryan, Ralph Venhaus. Phase 1/2 study of mRNA vaccine therapy + durvalumab (durva) ± tremelimumab (treme) in patients with metastatic non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B209.

Abstract A022: Phase 1/2 study to evaluate systemic durvalumab (durva) + intraperitoneal ONCOS-102 in patients with peritoneal disease who have epithelial ovarian (OC) or metastatic colorectal cancer (CRC)

Metastasis to the peritoneal cavity is associated with end-stage disease in many cancers, including epithelial ovarian cancer (OC) and colorectal cancer (CRC), both of which exhibit poor responses to checkpoint inhibitors. Oncolytic viruses may promote tumor recognition by the immune system. Evidence suggests that locoregional treatment with oncolytic viruses can be used to improve the efficacy of checkpoint inhibitors at both treated and distant tumor sites. ONCOS-102 is an oncolytic adenovirus encoding for granulocyte-macrophage colony stimulating factor (GMCSF). Durvalumab (durva), a checkpoint inhibitor, is a human IgG1 monoclonal antibody against programmed cell death ligand-1 (PD L1). This study evaluates the combination of intraperitoneally administered ONCOS-102 with systemic durva in patients with peritoneal disease who have histologically confirmed OC or metastatic CRC and have failed prior standard therapies.This ongoing phase 1/2, open-label study (NCT02963831) evaluates the safety and antitumor/biologic activity of durva (1500 mg intravenous, every 4 weeks x 12) + ONCOS-102 (intraperitoneal, weekly x 6); cyclophosphamide is given before the first ONCOS-102 dose. Phase 1 will follow a 3+3 design to evaluate the ONCOS 102 dose to be given with durva. Phase 2 will evaluate the activity of the combination using Simon’s 2-stage MINIMAX design. In Stage 1, the OC and CRC cohorts will enroll 18 and 13 patients, respectively. If ≥ 5 patients in the OC cohort or ≥ 1 patient in the CRC cohort are progression free at the end of Week 24 (PFS24W), then Stage 2 will enroll 15 and 14 additional patients in the OC and CRC cohorts for a total n of 33 and 27, respectively. The null/alternative hypotheses for PFS24W are 20/40% for OC and 5/20% for CRC. The null hypothesis will be rejected if ≥ 11 patients in the OC cohort or ≥ 4 patients in the CRC cohort experience PFS24W. The primary endpoints are safety/tolerability per Common Terminology Criteria for Adverse Events (CTCAE) for phase 1 and PFS24W rate by RECIST 1.1 for phase 2. Secondary endpoints are safety and tolerability, response rate at 8 and 24 weeks, progression-free survival, and overall survival. Exploratory endpoints are immunologic effects in tumors and peripheral blood. Enrollment opened 07 September 2017. As of 27 June 2018, 4 patients are enrolled; enrollment is ongoing.

Citation Format: Dmitriy Zamarin, Kunle Odunsi, Brian Slomovitz, Vanessa M. Hubbard-Lucey, Danielle McCabe, Lisa Shohara, Paul Schwarzenberger, Toni Ricciardi, Mary Macri, Aileen Ryan, Anne-Kirsti Aksnes, Lukasz Kuryk, Ralph Venhaus. Phase 1/2 study to evaluate systemic durvalumab (durva) + intraperitoneal ONCOS-102 in patients with peritoneal disease who have epithelial ovarian (OC) or metastatic colorectal cancer (CRC) [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A022.

Phase 1/2 study of in situ vaccination with tremelimumab + intravenous (IV) durvalumab + poly-ICLC in patients with select relapsed, advanced cancers with measurable, biopsy-accessible tumors

TPS3106

Background: Immunotherapy has demonstrated promising antitumor activity in various advanced cancers. Combined tumor targeting from multiple drugs with unique mechanisms may provide further improved outcomes. Tremelimumab (TRE) is a CTLA-4 antibody and durvalumab (DUR) blocks PD-L1. Poly-ICLC is a toll-like receptor 3 agonist. Intratumoral (intra-T) injection of poly-ICLC directly alters the tumor microenvironment (TME), and by creating an in situ vaccination, may trigger a clinically effective systemic anti-tumor response when also combined with DUR and TRE. Methods: This is an ongoing Phase 1/2, open-label, multicenter study (NCT02643303). The study evaluates the use of intra-T administration of TRE and IV DUR + poly-ICLC (intra-T and intramuscular [IM]) to determine the safety, preliminary efficacy and immune activity of this regimen in patients with advanced, measurable, biopsy-accessible tumors: head and neck squamous cell carcinoma, breast cancer, sarcoma, merkel cell carcinoma, cutaneous T-cell lymphoma, melanoma, genitourinary cancer, and other solid tumors. Phase 1 determines the recommended combination dosing (RCD) for the regimen with dose de-escalation based on dose limiting toxicities (DLTs) and standard 3 + 3 rules. Starting doses are: DUR, 1500 mg IV; TRE, 75 mg IV; TRE, 10 mg intra-T; poly-ICLC, 1 mg intra-T/IM. Phase 1 starts with Cohort 1A (DUR + poly-ICLC). Upon demonstration of tolerability, enrollment proceeds with Cohort 1B (DUR + IV TRE + poly-ICLC) and Cohort 1C (DUR + intra-T TRE + poly-ICLC). The RCD is the highest dose at which < 2/6 patients have DLTs. In Phase 2, up to 66 evaluable patients are treated using the RCD regimen, with enrollment of 6 patients per tumor type initially, and enrollment of 6 additional patients per 3 tumor types contingent upon at least 1 response among the initial 6 patients. Study endpoints are RCD and safety, objective response rate, progression-free survival, and overall survival. Exploratory endpoints are biological activity, including effects on the TME and immunological responses. Enrollment opened on 28 Dec 2016. Clinical trial information: NCT02643303.

Phase 1 study to evaluate the safety and efficacy of immunotherapy with tremelimumab and durvalumab in multiple myeloma patients receiving high dose chemotherapy and autologous stem cell transplant (HDT/ASCT) + peripheral blood lymphocyte (PBL) reinfusion

TPS8051

Background: Multiple myeloma (MM) remains an incurable hematologic malignancy despite the advent of new classes of drugs, including immunomodulatory agents, proteasome inhibitors, and monoclonal antibodies. The success and synergistic activity of immunotherapy (IMT) in solid tumors and hematologic malignancies has fueled their investigation in MM. HDT/ASCT as consolidation or as treatment for relapse remains a cornerstone for improving overall survival. HDT/ASCT transiently eliminates immune-suppressive cell populations and provides a viable IMT platform. Reinfusion of PBLs harvested pre-HDT induces immune responses, supporting its inclusion in IMT combinations. This study evaluates the effect of IMT, using tremelimumab (T), an anti-CTLA-4 monoclonal antibody, and durvalumab (D), an anti-PD-L1 monoclonal antibody, together with autologous PBL reinfusion and starting T ± D at Day 100 and earlier (Day 30) post-ASCT. Methods: This ongoing Phase 1, open-label, multicenter study (NCT02716805) evaluates the safety and preliminary efficacy of T and D administered on 2 schedules in MM patients at high risk for relapse as outlined below. Cohort initiation requires dose-limiting toxicity in < 2/6 patients in the previous cohort. The primary endpoint is safety. Secondary endpoints are objective response rate per IMWG, minimal residual disease, progression free and overall survival, and 100-day ASCT-related mortality. Exploratory endpoints include immunological effects and immune response. Enrollment opened 18 Nov 2016. As of 31 Dec 2016, 1 patient is enrolled in Cohort 1; enrollment is ongoing. Clinical trial information: NCT02716805. [Table: see text]

Phase 2 study to evaluate safety and efficacy of MEDI4736 (durvalumab [DUR]) in glioblastoma (GBM) patients: An update

2042

Background: DUR is a human IgG1 monoclonal Ab against PD-L1. PD-1/PD-L1 blockade has shown benefit in solid tumors. PD-L1 is expressed by many GBM tumors while cytotoxic lymphocytes infiltrating GBM tumors often express PD-1; thus, there is a rationale for exploring PD-1/PD-L1 blockade in GBM. Bevacizumab (BEV) is a VEGF-specific angiogenesis inhibitor approved for recurrent GBM. PD-L1 blockade and angiogenesis inhibition may be synergistic. Methods: This ongoing Phase 2, multicenter, open-label study (NCT02336165) evaluates safety/efficacy of DUR (10 mg/kg every 2 wks) in 5 GBM cohorts. Secondary endpoints are safety/tolerability, median PFS/OS, overall response rate and quality of life measures. Exploratory endpoints: neurologic function and immunocorrelative biomarkers. Results: Enrollment as of 16 Dec 2016: Cohort A = 35, B = 31, B2 = 34, B3 = 34, and C = 20 pts. Enrollment is ongoing for Cohorts A and C. This is an update to the interim analysis that was reported for Cohort B (male: 83.9%; mean age: 54.0 [24-77] years; baseline ECOG PS0: 51.6%, PS1: 48.4%; baseline measurable lesions: 77.4%). Incidences of treatment-related adverse events (TRAEs) by max CTCAE grade (Gr) were Gr1: 35.5%; Gr2: 41.9%; Gr3: 9.7%; and Gr4/5: 0%. Most common TRAEs (≥3 pts): fatigue, headache, hemiparesis, gait disturbance, increased AST, and decreased platelets/WBCs/lymphs. Six of 30 evaluable pts were progression free at 6 months (Kaplan-Meier, 20.0% [90% CI: 9.7, 33.0]); best overall response: partial response, 4 (13.3%) pts and stable disease, 14 (46.7%). At 1 year, 4 pts remained progression free (longest PFS ongoing at 80 wks, n=2). OS-6 and OS-12 are 59.0 and 44.4%, respectively. As of 16 Dec 2016, 7 pts remain alive (longest OS ongoing at 86 wks). Conclusions: DUR monotherapy appears to be well tolerated and shows durable activity in a subset of BEV-naïve recurrent GBM pts. Study is ongoing. Clinical trial information: NCT02336165. [Table: see text]

Phase 1 study to evaluate the safety and tolerability of MEDI4736 (durvalumab, DUR) + tremelimumab (TRE) in patients with advanced solid tumors

3069

Background: DUR is a human IgG1 monoclonal antibody (mAb) that blocks PD-L1. TRE is a human IgG2 mAb inhibitor of CTLA-4. Blocking these checkpoints can result in antitumor activity in some solid tumors. The targets for DUR and TRE are non-redundant, providing sound rationale for clinical testing of the combination. Methods: This is an ongoing Phase 1, multicenter, open label study (NCT01975831) with a dose escalation (3+3 design) and subsequent expansion phase. Patients (pts) with renal cell carcinoma (RCC), cervical (CC), colorectal (CRC), non-triple-negative breast (NTNBC), ovarian (OC), non-small cell lung, or head and neck cancer are eligible. Primary endpoints are safety/tolerability and identification of maximum tolerated dose (MTD) of the combination. Secondary objectives include tumor response and progression-free/overall survival. Results: As of 16 Dec 2016, 105 pts were treated. DUR 1500 mg every 4 weeks (Q4W) and TRE 75 mg Q4W X 4 was the regimen used for opening the expansion phase. Dose-limiting toxicities were reported in 4 pts: diarrhea, colitis, abnormal liver function tests (abn LFTs), and hyponatremia. The majority of treatment-related AEs (TRAEs) were Grades (Gr) 1 and 2. TRAEs ≥ Gr 3 were reported in 12 pts; the majority were diarrhea/colitis (n = 5) and abn LFTs (n = 4) and responded to established treatment algorithms. There was 1 Gr 5 TRAE: multi organ failure. No new toxicities were identified. The preliminary responses by tumor type with n ≥ 10 pts are shown in the table below. Responses were seen in OC and RCC at the Cohort 2 dose escalation level (DUR 1/TRE 3 mg/kg). There were 4 cases of SD > 24 weeks: CC, n=2; CRC, n=1; OC, n=1. PD-L1 status was not tested. Conclusions: The DUR + TRE combination has a manageable safety profile, with preliminary evidence of clinical activity. These data support continued study of the combination therapy; the study is ongoing. Clinical trial information: NCT01975831. [Table: see text]

Phase 1 study to evaluate safety and efficacy of ipilimumab + nivolumab + external beam radiotherapy in patients with metastatic melanoma

TPS9591

Background: Immunotherapy (IMT) with checkpoint blocking antibodies has led to progress in metastatic melanoma with 3 FDA-approved drugs, including the combination of ipilimumab (IPI), a CTLA-4 antibody, and nivolumab (NIVO), a PD-1 antibody. Although radiotherapy (RT) is primarily used as local palliative therapy in metastatic melanoma, it also possibly affects systemic antitumor immunity. Preclinical data suggest RT alters the tumor microenvironment and renders tumor cells more susceptible to immunologically-mediated disease regression. These preclinical immunologic effects of RT have been shown to vary by RT dose and fractionation. We are now conducting the first clinical trial in patients to evaluate the triple combination of IPI + NIVO + RT using 2 different dose/fractionation schemes of RT. Methods: This ongoing Phase 1, open-label, multicenter study (NCT02659540) evaluates safety, efficacy, and immunologic effects of IPI + NIVO + RT in 18 patients with unresectable stage IV melanoma. Patients must have 1 melanoma metastasis that can be safely irradiated for palliative purposes and at least 1 measurable lesion that will not be irradiated. Patients receive concurrent IPI (3 mg/kg) and NIVO (1 mg/kg) every 3 weeks (Q3W) x 4, followed by NIVO monotherapy (240 mg Q2W), with RT initiated between the first and second doses of IPI + NIVO. In Cohort A, the irradiated metastasis receives a conventionally fractionated low dose of 30 Gy in 10 fractions of 3 Gy each over 2 weeks. If ≤7 of 9 patients (78%) in Cohort A have Grade 3/4 drug- or radiation-related adverse events, safety is deemed acceptable and Cohort B enrollment opens. In Cohort B, the irradiated metastasis receives a hypofractionated high dose of 27 Gy in 3 fractions of 9 Gy each over 2 weeks. The primary endpoint is safety. Secondary endpoints are objective response rate and disease control rate by RECIST and immune-related RECIST measured at Weeks 12 and 18, duration of response, progression-free survival, and overall survival. Exploratory endpoints include correlative studies of immunological effects. Enrollment opened on 05 Aug 2016. As of 31 Dec 2016, 4 patients are enrolled in Cohort A; enrollment is ongoing. Clinical trial information: NCT02659540.

Radium-223 (Ra-223) re-treatment (Re-tx): First experience from an international, multicenter, prospective study in patients (Pts) with castration-resistant prostate cancer and bone metastases (mCRPC)

197

Background: Ra-223 tx for up to 6 injections (inj) is indicated for pts with symptomatic bone metastases. Ra-223 tx beyond 6 inj has not been previously reported. Herein we report the first safety and efficacy findings of Ra-223 re-tx from an international prospective trial in mCRPC pts. Methods: Pts with CRPC with ≥ 2 bone mets who completed 6 initial Ra-223 inj with no disease progression in bone and progressed after initial tx were potentially eligible for Ra-223 re-tx, provided that hematologic (heme) parameters were adequate. No concomitant cytotoxic agents were allowed; other agents were allowed at investigator discretion. Primary objective was safety. Exploratory objectives were time to radiographic bone progression, time to ALP progression, and radiographic progression-free survival (rPFS) based on MRI/CT and bone scans performed q 3 mo. Results: 44 pts had Ra-223 re-tx, 29 (66%) completed tx with all 6 inj; median (med) number inj = 6. Med time from initial Ra-223 tx = 6 mo. Besides prior Ra-223, all pts had ≥ 2 hormonal regimens; 45% had ≥ 1 chemotherapy regimen. 32 (73%) failed novel hormonal agents, eg, abiraterone and enzalutamide. Baseline characteristics were comparable to ALSYMPCA (Table). No new safety concerns were noted; incidence of tx-emergent adverse events (TEAEs) in re-tx pts was comparable to or lower than ALSYMPCA (Table). Only 2 re-tx pts had grade 3 heme TEAEs. Only 1 pt had radiographic bone progression; med time to ALP progression was not reached. Med rPFS = 9.9 mo. Conclusions: Ra-223 re-tx was well tolerated in this highly selected population, with minimal heme toxicity, and provided continued control of disease progression in bone. Clinical trial information: NCT01934790. [Table: see text] [Table: see text]

Multicenter phase II study of a combination of cyclosporine a, methotrexate and mycophenolate mofetil for GVHD prophylaxis: results of the Chinese Bone Marrow Transplant Cooperative Group (CBMTCG)

Background

Improvement of current GVHD prophylactic therapies remains an important goal in the allo-HSCT. We have described a novel prophylaxis regimen in a single institution trial. The Chinese Bone Marrow Transplant Cooperative Group (CBMTCG) initiated a phase II multicenter study.

Methods

The study was designed as a prospective, single arm phase II open-label, multicenter clinical trial. The primary endpoint was improvement of aGVHD by 25% over historical control (40%) in Chinese patients. 508 patients were enrolled. All of the patients received cyclosporine A (CsA), methotrexate (MTX) and mycophenolate mofetil (MMF) (0.5-1.0 g daily for 30 days) as GVHD prophylaxis regimen.

Results

The primary endpoint was met with cumulative incidences of grades 2 to 4 and grades 3 to 4 aGVHD of 23.2% and 10.3%, respectively. Incidence for cGVHD was 67.4%. The non-relapse mortality (NRM) rate was 18.4% at 2 years. The probabilities of leukemia free survival (LFS) for non-advanced stage and advanced stage patients at 2 years were 69.7% and 44.8% respectively (p = 0.000). Recipient age ≥ 40 years, advanced stage and Busulfan-Fludarabine(BuFlu) conditioning regimen were identified as major risk factors for aGVHD. Recipient age ≥ 40 years, BuFlu conditioning regimens, female donor/male recipient and prior aGVHD were associated with cGVHD. Despite lower RM (relapse mortality), patients with grade 2–4 aGVHD had higher NRM and worse OS and LFS compared to patients with grade 0–1 aGVHD. In contrast, patients with cGVHD had better OS and LFS and lower RM compared to patients without cGVHD.

Conclusion

The novel GVHD regimen decreased the risk for aGVHD by 42% without improving the risk for cGVHD compared to historical controls. Development of aGVHD was associated with worse OS and LFS as well as higher NRM. In contrast, cGVHD was associated with improved OS and LFS likely attributed to a GVL effect.

Requirement of TPO/c-mpl for IL-17A-induced granulopoiesis and megakaryopoiesis

IL-17A is a critical, proinflammatory cytokine essential to host defense and is induced in response to microbial invasion. It stimulates granulopoiesis, leading to neutrophilia, neutrophil activation, and mobilization. TPO synergizes with other cytokines in stimulating and expanding hematopoietic progenitors, also leading to granulopoiesis and megakaryopoiesis, and is required for thrombocytopoiesis. We investigated the effects of in vivo expression of IL-17A on granulopoiesis and megakaryopoiesis in TPO receptor c-mpl-/- mice. IL-17A expression expanded megakaryocytes by 2.5-fold in normal mice but had no such effect in c-mpl-/- mice. The megakaryocyte expansion did not result in increased peripheral platelet counts. IL-17A expression did not impact bone marrow precursors in c-mpl-/- mice; however, it expanded splenic precursors, although to a lesser extent compared with normal controls (CFU-HPP). No peripheral neutrophil expansion was observed in c-mpl-/- mice. Moreover, in c-mpl-/- mice, release of IL-17A downstream cytokines was reduced significantly (KC, MIP-2, GM-CSF). The data suggest that IL-17A requires the presence of functional TPO/c-mpl to exert its effects on granulopoiesis and megakaryopoiesis. Furthermore, IL-17A and its downstream cytokines are important regulators and synergistic factors for the physiologic function of TPO/c-mpl on hematopoiesis.

CD34+ hematopoietic stem cells support entry and replication of poliovirus: a potential new gene introduction route

Pluripotent hematopoietic stem cells (HSC) are critical in sustaining and constantly renewing the blood and immune system. The ability to alter biological characteristics of HSC by introducing and expressing genes would have enormous therapeutic possibilities. Previous unpublished work suggested that human HSC co-express CD34 (cluster of differentiation 34; an HSC marker) and CD155 (poliovirus receptor; also called Necl-5/Tage4/PVR/CD155). In the present study, we demonstrate the co-expression of CD34 and CD155 in primary human HSC. In addition, we demonstrate that poliovirus infects and replicates in human hematopoietic progenitor cell lines. Finally, we show that poliovirus replicates in CD34+ enriched primary HSC. CD34+ enriched HSC co-express CD155 and support poliovirus replication. These data may help further understanding of poliovirus spread in vivo and also demonstrate that human HSC may be amenable for gene therapy via poliovirus-capsid-based vectors. They may also help elucidate the normal function of Necl-5/Tage4/PVR/CD155.

Experimental chronic hepatitis B infection of neonatal tree shrews (Tupaia belangeri chinensis): a model to study molecular causes for susceptibility and disease progression to chronic hepatitis in humans

BACKGROUND

Hepatitis B virus (HBV) infection continues to be an escalating global health problem. Feasible and effective animal models for HBV infection are the prerequisite for developing novel therapies for this disease. The tree shrew (Tupaia) is a small animal species evolutionary closely related to humans, and thus is permissive to certain human viral pathogens. Whether tree shrews could be chronically infected with HBV in vivo has been controversial for decades. Most published research has been reported on adult tree shrews, and only small numbers of HBV infected newborn tree shrews had been observed over short time periods. We investigated susceptibility of newborn tree shrews to experimental HBV infection as well as viral clearance over a protracted time period.

RESULTS

Forty-six newborn tree shrews were inoculated with the sera from HBV-infected patients or tree shrews. Serum and liver samples of the inoculated animals were periodically collected and analyzed using fluorescence quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, Southern blot, and immunohistochemistry. Six tree shrews were confirmed and four were suspected as chronically HBV-infected for more than 48 (up to 228) weeks after inoculation, including three that had been inoculated with serum from a confirmed HBV-infected tree shrew.

CONCLUSIONS

Outbred neonatal tree shrews can be long-term chronically infected with HBV at a frequency comparable to humans. The model resembles human disease where also a smaller proportion of infected individuals develop chronic HBV related disease. This model might enable genetic and immunologic investigations which would allow determination of underlying molecular causes favoring susceptibility for chronic HBV infection and disease establishment vs. viral clearance.

IL-17 is a potent synergistic factor with GM-CSF in mice in stimulating myelopoiesis, dendritic cell expansion, proliferation, and functional enhancement

OBJECTIVE

Interleukin (IL)-17, which now defines the Th(17) immune response, is a critical cytokine expressed and required for stress granulopoiesis during microbial invasion. Dendritic cells (DC) can instigate this response by inducing IL-17 expression in CD4(+) T cells. Besides IL-17, microbial invasion also stimulates production of the DC growth factor granulocyte-macrophage colony-stimulating factor (GM-CSF). The objective was the in vitro and in vivo investigation of IL-17 on DC proliferation and function in mice.

MATERIALS AND METHODS

Murine IL-17 (mIL-7) or murine GM-CSF (mGM-CSF), or both, was expressed in C57BL6 mice using adenoviral technology to assess hematopoietic and DC changes. The E-22 tymoma tumor cell line using a previously described vaccinia virus ovalbumin/LacZ murine tumor model was employed to study effects on tumor rejection.

RESULTS

The combination of mIL-17 and mGM-CSF increased peripheral neutrophila by 28-fold and splenic colonies by 11- and 14-fold over each individual factor in mice, respectively. The effect of mIL-17 by itself on murine DCs in vitro and in vivo was minimal; however, the combination greatly enhanced the stimulating effects of mGM-CSF, increasing the total numbers of CD14b/c(+) spleen DC by fourfold, as well as their function measured by enhanced endocytosis. Mixed lymphocyte reactions using mIL-17/mGM-CSF cultured DCs stimulator cells enhanced lymphocyte responses by twofold over mGM-CSF alone. Vaccination against LacZ in the C57BL6 E22 syngenic thymoma tumor model effectively delayed tumor growth in animals pretreated with the mIL-17/mGM-CSF combination prior to vaccination.

CONCLUSIONS

mIL-17 effectively synergizes with mGM-CSF in stimulating granulopoiesis and DC expansion, as well as in functional enhancement of DCs.

Targeted agents for chronic myelogenous leukemia: will that be the end of allogeneic bone marrow transplantation for that disease?

Although the drug imatinib has been accepted as the treatment of choice for chronic myelogenous leukemia (CML) in chronic phase (CP) throughout the Western world, allogeneic stem cell transplantation (allo-SCT) continues to remain a widely practiced first-line treatment in countries with limited health care budgets. The rationale is not scientific, but largely economically based. We analyzed a cohort of 46 CML patients who participated in a graft-versus-host disease (GVHD) prophylaxis clinical trial and underwent related HLA-matched allogeneic peripheral blood stem cell transplantation. The median time of follow-up in surviving patients was 43 months (range: 4-89 months). Risk stratification of the population was done by European Blood and Marrow Transplant (EBMT) criteria. The estimated probabilities of overall survival (OS) and leukemia-free survival (LFS) at 3 years in low EBMT risk score (0-2) patients were both 91%, respectively. We conclude that in countries with restricted access to imatinib, allo-SCT should be considered early on as front-line therapy. Continued research support for bone marrow transplantation will be needed to make a global impact on this disease.

Biochemical characterization of riboflavin carrier protein (RCP) in prostate cancer

Riboflavin carrier protein (RCP) is a growth- and development-specific protein. Here, we characterized the expression of this protein in prostate cancer by polyclonal and monoclonal antibodies against chicken RCP. RCP was localized to both androgen-dependent and independent prostate cancer cell lines. Compared to controls, RCP was over-expressed in all 45 prostate adenocarcinomas, irrespective of the Gleason's score or the stage of the disease. The identified RCP had a molecular weight of 38 kDa, similar to RCP purified from chicken. Presence of this protein was also confirmed by siRNA inhibition analysis. Antibodies to chicken RCP inhibited incorporation of tritiated thymidine into DNA and prevented riboflavin uptake in PC3 prostate cancer cells, suggesting a critical function of this protein in prostate cancer cell growth. These data suggest that RCP can be used as a tumor biomarker in prostate cancer.

Combination of CsA, MTX and low-dose, short-course mycophenolate mofetil for GVHD prophylaxis

In an effort to reduce the incidence and severity of acute GVHD (aGVHD), we have developed a new prophylaxis regimen combining cyclosporine and MTX with a short 30-day course of low-dose (500 mg per day) mycophenolate mofetil. This regimen was studied prospectively 100 patients undergoing HLA-matched and 1-antigen-mismatched allogeneic peripheral blood SCT from related donors. The cumulative incidence of aGVHD was 16% (grades II-IV (9.5%) and grades III-IV (1%)). The cumulative incidence of chronic GVHD (cGVHD) was 53% with 28% extensive cGVHD. The cumulative incidence of transplant-related mortality at 100 days and 3 years were 6 and 13%. The estimated probabilities of disease-free survival at 3 years in standard- and high-risk patients were 77 and 30%, respectively (P<0.0001). The estimated probabilities of overall survival at 3 years in standard- and high-risk patients were 77 and 37%, respectively (P<0.0001). These data show a substantial decrease in the risk of developing aGVHD without an increase in relapse or any adverse impact on survival in standard-risk patients.

IL-17F/IL-17R interaction stimulates granulopoiesis in mice

OBJECTIVE

IL-17F, a member of the interleukin (IL)-17 cytokine family, most closely resembles IL-17A structurally. IL-17A is a potent stimulator of granulopoiesis; its expression is induced in response to microbial challenge. Although IL-17F is considered to be a weak IL-17A analog that is also mediating its effect via IL-17R, its exact role and in vivo functions are unknown. Our goal was to determine the in vivo activity of IL-17F on granulopoiesis as well as on release of granulopoiesis-stimulating downstream cytokines in mice and directly compare its effect to IL-17A.

MATERIALS AND METHODS

Murine IL-17A (mIL-17A) or IL-17F (mIL-17F) was expressed in vivo in C57BL6 mice using adenoviral gene transfer technology. Peripheral cell counts were assessed as well as hematopoietic precursors using colony-forming assays at set time points. Downstream cytokines were measured using enzyme-linked immunosorbent assay and reverse transcriptase polymerase chain reaction.

RESULTS

We found mIL-17F to have similar expression kinetics as mIL-17A in splenocytes in vitro and in vivo, following challenge with microbial agents. Overexpression of mIL-17F in vivo resulted in similar neutrophilia and only in slightly reduced myeloid progenitor expansion when compared to mIL-17A. In vivo, there was no difference in releases for granulocyte-macrophage colony-stimulating factor; regulated on activation, normal T expressed and secreted; interferon-inducible protein-10; IL-6; and monocyte chemotactic protein-1 between either cytokine. IL-1A, macrophage inflammatory protein -2 (MIP), KC, and granulocyte colony-stimulating factor expression was approximately half of that seen with mIL-17A.

CONCLUSION

Both IL-17A and IL-17F are induced by similar stimuli, have similar expression kinetics and despite only minimal in vitro activity for IL-17F, surprisingly they exert similar in vivo bioactivity. IL-17F bioactivity appears to be augmented in vivo through mechanisms that require further investigation.

Phase I study of flavopiridol in combination with Paclitaxel and Carboplatin in patients with non-small-cell lung cancer

PURPOSE

The aim of this study was to evaluate the safety and tolerability of escalating doses of flavopiridol/ paclitaxel/carboplatin in patients with advanced-stage non-small-cell lung cancer (NSCLC) as well as the pharmacokinetics and activity of flavopiridol when used in combination with paclitaxel/carboplatin.

PATIENTS AND METHODS

Eligible patients aged 18-75 years with previously untreated stage IIIB/IV NSCLC received paclitaxel 175 mg/m2 over 3 hours followed by carboplatin area under the curve (AUC) 5 over 1 hour and flavopiridol 30-85 mg/m2 over 24 hours every 3 weeks for 3 cycles.

RESULTS

Eighteen patients were enrolled at 4 sites in the United States and received flavopiridol 30 mg/m2 (n = 3), 50 mg/m2 (n = 6), 70 mg/m2 (n = 3), or 85 mg/m2 (n = 6). No dose-limiting toxicities (DLTs) occurred at the 50-mg/m2 or 70-mg/m2 dose levels. Two patients treated at the 85-mg/m2 dose level experienced cardiovascular events that did not meet the criteria for DLT but were fatal in 1 case, prompting no further flavopiridol dose escalations and establishment of 70 mg/m2 as the maximum tolerated dose. The most frequently reported adverse events across all dose levels combined were nausea (89%), asthenia (67%), and diarrhea (56%). Flavopiridol concentrations increased rapidly, reached a plateau, and showed a multiphasic decline after the 24-hour infusion. Of 12 patients evaluable for efficacy, 8 achieved a partial response, and 4 had stable disease.

CONCLUSION

Flavopiridol in doses <or= 70 mg/m2 in a 24-hour infusion can safely be combined with a 3-hour infusion of paclitaxel 175 mg/m2 and a 1-hour infusion of carboplatin AUC 5.

Randomized phase III trial comparing bexarotene (L1069-49)/cisplatin/vinorelbine with cisplatin/vinorelbine in chemotherapy-naive patients with advanced or metastatic non-small-cell lung cancer: SPIRIT I

PURPOSE

This study evaluated whether the combination of the synthetic rexinoid bexarotene with first-line cisplatin/vinorelbine therapy provides additional survival benefit in patients with advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with stage IIIB with pleural effusion or stage IV NSCLC and Eastern Cooperative Oncology Group performance status 0 to 1 were randomly assigned to open-label bexarotene 400 mg/m(2)/d with cisplatin/vinorelbine or to cisplatin/vinorelbine alone. Antilipid agents were initiated on or before day 1 in the bexarotene arm. Primary efficacy end point was overall survival. Primary, secondary and supportive efficacy analyses were conducted.

RESULTS

A total of 623 patients (312 control, 311 bexarotene) were enrolled. Overall, no significant difference in survival occurred between the two treatment groups. However, an unplanned retrospective analysis showed that a subpopulation of bexarotene patients (n = 98 of 306) who experienced National Cancer Institute grade 3/4 hypertriglyceridemia had longer median survival compared with control patients (12.3 v 9.9 months; log-rank P = .08). Within that subgroup, those who benefited the most included males, smokers, those with stage IV disease, and those with a 6-month prior weight loss of 5% or more. Incidence, type and severity of grade 3/4 adverse events were comparable between arms, except for leukopenia (higher in chemotherapy arm) and hyperlipemia, hypothyroidism, dyspnea, and headache (higher in chemotherapy/bexarotene arm).

CONCLUSION

The addition of bexarotene to first-line chemotherapy did not increase survival in patients with advanced NSCLC. However, a subgroup (32%) of bexarotene-treated patients developing high-grade hypertriglyceridemia appeared to have better survival (12.3 months) than controls; thus triglyceride response may be a biomarker of survival benefit with bexarotene.

Phase I trial of IL-2 plasmid DNA with electroporation in metastatic melanoma

8578

Background: Significant toxicity limits the systemic delivery of high-dose recombinant Interleukin-2 (IL-2). An alternative method for extended dosing of IL-2 that may reduce toxicity is by intratumoral injection of IL-2 plasmid DNA (pDNA) with electroporation (EP). Methods: A phase I dose-escalation trial is ongoing in subjects with metastatic melanoma to evaluate the safety of intratumoral delivery of IL-2 pDNA (VCL-IM01, Vical Inc., San Diego, CA) followed by EP (MedPulser DNA EPT System, Inovio, San Diego, CA). Eligible subjects have recurrent metastatic melanoma; an injectable lesion = 1 cm2 and < 25 cm2; ECOG 0 or 1; LDH = 1.5 × ULN, and no brain or liver metastases. In the dose-escalation stage of the trial, 3 subjects in each dose cohort received up to 2 cycles of treatment, each consisting of 4 weekly injections followed by a 4-week observation period. Dose levels included 0.5, 1.5, 5.0 mg/tumor, and 15.0 mg (5 mg in each of 3 tumors). A safety assessment was conducted for each cohort prior to enrollment of the next cohort. In the 2nd trial stage, 17 subjects are to be enrolled at the maximum tolerated dose (MTD). The observation period is shortened to 2 weeks between cycles. For all subjects, safety is assessed at every visit. Results: 12 subjects (7 male, 5 female) were enrolled in the dose escalation stage, 3 subjects at each dose. Ages range from 38 to 86 years. No Grade 3 or 4 adverse events (AEs) were reported related to study drug or procedures. All related AEs (12 reported) were Grade 1: 5 related to study drug, 4 to the EP procedure, and 3 to both. Injection site pain was the most common AE. No dose-limiting toxicities occurred; thus the MTD was defined as the 15 mg dose (5 mg/tumor in 3 tumors). To date, 6/17 subjects in Stage 2 of the trial (5 mg/tumor, up to 3 tumors injected) have been enrolled with no Grade 3 or 4 AEs related to study drug or injection/EP procedures. Physicians have observed responses in treated and untreated lesions. Overall response data will be presented. Conclusions: Intratumoral administration of IL-2 pDNA with EP appears safe and well tolerated in 18 patients with metastatic melanoma when given up to a 15 mg dose (5 mg/tumor). Preliminary indications of decreased tumor size suggest local and systemic activity of IL-2 pDNA with EP.

No significant financial relationships to disclose.

Retrovirus molecular conjugates: a versatile and efficient gene transfer vector system for primitive human hematopoietic progenitor cells

In principle, transient nongenetic modification of a noninfectious gene transfer virus enabling a one time infection and transduction of human cells could eliminate the risk of formation of replication competent virus. Formation of a molecular conjugate vector by conjugation of noninfective ecotropic murine Moloney leukemia virus to polylysine (eMMLV-PL) enabled high-efficiency transduction of human HPC using in vitro and in vivo assays. Xenotransplanted NOD-SCID mice durably expressed the transgene in human leukocytes and human progenitor cells with eMMLV-PL achieving three-fold increased transduction efficiency when directly compared to optimized amphotropic MMLV (aMMLV) transduction. Both aMMLV and eMMLV assembled conjugate vectors showed similar transduction efficiency indicating predominant polylysine-mediated uptake. Integration of retroviral sequences was determined from individual human HPC recovered from eMMLV-PL-xenotransplanted animals. This simple and versatile concept of conjugate gene transfer vectors has the potential to enhance transduction efficiency as well as to improve certain safety aspects of human gene therapy. Moreover, because it permits effective cellular internalization of particles, this concept of molecular conjugates can be used as research tool to investigate the interactions of otherwise noninfectious viruses or modified viral particles at the genomic level.

IL-17 receptor knockout mice have enhanced myelotoxicity and impaired hemopoietic recovery following gamma irradiation

IL-17A is a T cell-derived proinflammatory cytokine required for microbial host defense. In vivo expression profoundly stimulates granulopoiesis. At baseline, the hemopoietic system of IL-17R knockout mice (IL-17Ra(-/-)) is, with the exception of increased splenic progenitor numbers, indistinguishable from normal control mice. However, when challenged with gamma irradiation, hemopoietic toxicity is significantly more pronounced in IL-17Ra(-/-) animals, with the gamma irradiation-associated LD(50) being reduced by 150 rad. In spleen-derived T cells, gamma irradiation induces significant murine IL-17A expression in vivo but not in vitro. After sublethal radiation injury (500 rad), the infusion of purified CD4(+) T cells enhances hemopoietic recovery. This recovery is significantly impaired in IL-17Ra(-/-) animals or after in vivo blockade of IL-17Ra in normal mice, resulting in a reduction of hemopoietic precursors by 50% and of neutrophils by 43%. Following sublethal radiation-induced myelosuppression, in vivo overexpression of murine IL-17A in normal mice substantially enhanced granulopoietic restoration in mice with a 4-fold increase in neutrophils and splenic precursors on day 8 (CFU-granulocyte-macrophage/granulocyte-erythrocyte-megakaryocyte-monocyte, CFU-high proliferative potential), as well as 2- and 3-fold increases of bone marrow precursors, respectively. This establishes IL-17A as a hemopoietic response cytokine to radiation injury in mice and an inducible mechanism that is required for recovery of granulopoiesis after radiation injury.

Phase II study of a TGF-β2 antisense gene modified allogeneic tumor cell vaccine (Lucanix) in advanced NSCLC

7018

Background: Lucanix (L) is a non-viral gene based allogeneic tumor cell vaccine which demonstrates enhancement of tumor antigen recognition as a result of Transforming Growth Factor (TGF-β2) inhibition. Methods: We performed a randomized dose variable phase II trial involving stage IIIB/IV non small cell lung cancer (NSCLC). Each patient received one of 3 doses (1.25, 2.5, 5.0x107 cells/injection) of L, given intradermally, to a maximum of 16 injections either monthly or every other month. Immune function, safety and anticancer activity were monitored. Results: Sixty-one patients (15 IIIB/ 46 IV; 51/61 (84%) ≥ prior cytotoxic therapy), received a total of 417 vaccinations. No significant (≥ grade 3) adverse events probably or definitely associated with administration of the vaccine were observed. A dose-related survival difference was demonstrated in patients who received ≥ 2.5 × 107 cells/injection versus those who received <2.5 × 107 cells/injection (p=0.0151). The percent of patients surviving 1 and 2 years was 61% and 52% for the high dose group and 40% and 13% for the low dose group. Fifteen percent of patients achieved a partial response. Cytokine production (IFN-γ, p=0.006; IL-6, p=0.004; IL4, p=0.007) was induced, antibody mediated response to vaccine HLA antigen was observed (p=0.014) and cell mediated response showed a correlation trend (p=0.086) in patients achieving stable disease or partial response (15%) compared to those with progressive disease. Conclusions: In conclusion, L is safe and well tolerated. A survival advantage is suggested in patients who receive ≥ 2.5x107 cells/injection thereby supporting the justification for further phase III evaluation. Phase III investigation is recommended.

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Critical role of IL-17 receptor signaling in acute TNBS-induced colitis

BACKGROUND

Inflammatory bowel diseases (IBDs) such as Crohn's disease and ulcerative colitis are characterized by recurrent inflammation in the gastrointestinal tract. Infiltration of CD4 lymphocytes and neutrophils is one of the predominant features of IBD.

MATERIALS AND METHODS

Recently, interleukin (IL)-23 and the downstream T cell-derived cytokine IL-17 have been found to be elevated in intestinal tissue and serum of IBD patients. However, the role of IL-17 and IL-17R signaling in gut inflammation is unknown. To examine this role, we investigated gut inflammation in wild-type or IL-17R knockout mice.

RESULTS

Using a model of acute trinitrobenzenesulfonic acid (TNBS)-induced colitis, we found that IL-17 was produced in colon tissue at 24 and 48 hours and that IL-17R knockout mice were significantly protected against TNBS-induced weight loss, IL-6 production, colonic inflammation, and local macrophage inflammatory protein-2 induction. This protection occurred in the presence of equivalent induction of local IL-23 and higher levels of IL-12p70 and interferon-gamma in IL-17R knockout mice compared with wild-type mice. Moreover, IL-17R knockout mice showed reduced tissue myeloperoxidase activity. Furthermore, overexpression of an IL-17R IgG1 fusion protein significantly attenuated colonic inflammation after acute TNBS.

CONCLUSIONS

These results demonstrate that IL-17R signaling plays a critical role in the development of TNBS-induced colitis and may represent a target for therapeutic intervention for IBD.

Interleukin-17A: A T-Cell-Derived Growth Factor for Murine and Human Mesenchymal Stem Cells

Interleukin-17A (IL-17A) is a proinflammatory cytokine expressed in activated T-cells. It is required for microbial host defense and is a potent stimulator of granulopoiesis. In a dose-dependent fashion, IL-17A expanded human mesenchymal stem cells (MSCs) and induced the proliferation of mature stroma cells in bone marrow-derived stroma cultures. Recombinant human interleukin-17A (rhIL-17A) nearly doubled colony-forming unit-fibroblast (CFU-f) frequency and almost tripled the surface area covered by stroma. In a murine transplant model, in vivo murine (m)IL-17A expression enhanced CFU-f by 2.5-fold. Enrichment of the graft with CD4(+) T-cell resulted in a 7.5-fold increase in CFU-f in normal C57BL/6, but only threefold in IL-17Ra(-/-) mice on day 14 post-transplant. In this transplant model, in vivo blockade of IL-17A in C57BL/6 mice resembled the phenotype of IL-17Ra(-/-) mice. Approximately half of the T-cell-mediated effect on MSC recovery following radiation-conditioned transplantation was attributed to the IL-17A/IL-17Ra pathway. Pluripotent MSCs have the potential of regenerating various tissues, and mature stroma cells are critical elements of the hematopoietic microenvironment (HME). The HME is pivotal for formation and maintenance of functional blood cells. As a newly identified stroma cell growth factor, IL-17A might have potential applications for novel treatment approaches involving MSCs, such as tissue graft engineering.

CD4+ T cell-independent DNA vaccination against opportunistic infections

Depletion or dysfunction of CD4+ T lymphocytes profoundly perturbs host defenses and impairs immunogenicity of vaccines. Here, we show that plasmid DNA vaccination with a cassette encoding antigen (OVA) and a second cassette encoding full-length CD40 ligand (CD40L), a molecule expressed on activated CD4+ T lymphocytes and critical for T cell helper function, can elicit significant titers of antigen-specific immunoglobulins in serum and Tc1 CD8+ T cell responses in CD4-deficient mice. To investigate whether this approach leads to CD4+ T cell-independent vaccine protection against a prototypic AIDS-defining infection, Pneumocystis (PC) pneumonia, we used serum from mice vaccinated with PC-pulsed, CD40L-modified DCs to immunoprecipitate PC antigens. Kexin, a PC antigen identified by this approach, was used in a similar DNA vaccine strategy with or without CD40L. CD4-deficient mice receiving DNA vaccines encoding Kexin and CD40L showed significantly higher anti-PC IgG titers as well as opsonic killing of PC compared with those vaccinated with Kexin alone. Moreover, CD4-depleted, Kexin-vaccinated mice showed a 3-log greater protection in a PC challenge model. Adoptive transfer of CD19+ cells or IgG to SCID mice conferred protection against PC challenge, indicating a role of humoral immunity in the protection. The results of these studies show promise for CD4-independent vaccination against HIV-related or other opportunistic pathogens.