Recombinant Erwinia asparaginase (JZP458) in acute lymphoblastic leukemia: results from the phase 2/3 AALL1931 study

AALL1931, a phase 2/3 study conducted in collaboration with the Children's Oncology Group, investigated the efficacy and safety of JZP458 (asparaginase erwinia chrysanthemi [recombinant]-rywn), a recombinant Erwinia asparaginase derived from a novel expression platform, in patients with acute lymphoblastic leukemia/lymphoblastic lymphoma who developed hypersensitivity/silent inactivation to Escherichia coli-derived asparaginases. Each dose of a pegylated E coli-derived asparaginase remaining in patients' treatment plan was substituted by 6 doses of intramuscular (IM) JZP458 on Monday/Wednesday/Friday (MWF). Three regimens were evaluated: cohort 1a, 25 mg/m2 MWF; cohort 1b, 37.5 mg/m2 MWF; and cohort 1c, 25/25/50 mg/m2 MWF. Efficacy was evaluated by the proportion of patients maintaining adequate nadir serum asparaginase activity (NSAA ≥0.1 IU/mL) at 72 hours and at 48 hours during the first treatment course. A total of 167 patients were enrolled: cohort 1a (n = 33), cohort 1b (n = 83), and cohort 1c (n = 51). Mean serum asparaginase activity levels (IU/mL) at 72 hours were cohort 1a, 0.16, cohort 1b, 0.33, and cohort 1c, 0.47, and at 48 hours were 0.45, 0.88, and 0.66, respectively. The proportion of patients achieving NSAA ≥0.1 IU/mL at 72 and 48 hours in cohort 1c was 90% (44/49) and 96% (47/49), respectively. Simulated data from a population pharmacokinetic model matched the observed data well. Grade 3/4 treatment-related adverse events occurred in 86 of 167 (51%) patients; those leading to discontinuation included pancreatitis (6%), allergic reactions (5%), increased alanine aminotransferase (1%), and hyperammonemia (1%). Results demonstrate that IM JZP458 at 25/25/50 mg/m2 MWF is efficacious and has a safety profile consistent with other asparaginases. This trial was registered at www.clinicaltrials.gov as #NCT04145531.

A Phase 2 Trial of KIR-Mismatched Unrelated Donor Transplantation Using in Vivo T Cell Depletion with Antithymocyte Globulin in Acute Myelogenous Leukemia: Children's Oncology Group AAML05P1 Study

Patients with acute myelogenous leukemia (AML) who undergo killer immunoglobulin-like receptor (KIR)-mismatched haploidentical hematopoietic stem cell transplantation (HSCT) have improved survival. Children's Oncology Group AAML05P1 is a prospective phase 2 trial of unrelated donor (URD) HSCT in which KIR typing of donors was available to the treating physician at donor selection, aiming to determine feasibility (defined as the ability to obtain donor samples from URDs and obtain KIR data before transplantation) of prospective selection of KIR-mismatched donors and effect on outcomes. Patients age ≤30 years with high-risk AML at presentation or relapsed AML were eligible; the study accrued 90 evaluable patients. After enrollment, as many as 5 potential URD samples were KIR-typed (including gene expression) in a central laboratory and results reported to the treating physician, who made the final donor selection. Cases were categorized as KIR-matched or KIR-mismatched using different published strategies. Overall survival (OS), disease-free survival (DFS), and relapse did not differ significantly by KIR mismatch status. Acute graft-versus-host disease (GVHD) was significantly lower in recipients of KIR-mismatched stem cells (35% versus 60%; P = .027). We examined DFS according to time to natural killer (NK) receptor recovery after HSCT. NK p44 recovery was significantly associated with KIR mismatch and with decreased DFS and increased relapse risk in multivariate Cox analysis (P = .006 and .009, respectively). We show that prospective selection of URD according to KIR type was feasible, acute GVHD was reduced, but survival did not differ using any model of KIR mismatch. However, the study enrolled mostly matched transplants, so ligand-ligand mismatch was rare, and thus the sample size was insufficient to determine potential benefit according to this model. Cord blood recipients demonstrated a trend toward improved DFS with KIR mismatch, but the study was not powered to detect a difference in this small subset of patients. Our data suggest that recovery of NK receptor expression might influence DFS after HSCT.

Sacituzumab Govitecan-hziy in Refractory Metastatic Triple-Negative Breast Cancer

BACKGROUND

Standard chemotherapy is associated with low response rates and short progression-free survival among patients with pretreated metastatic triple-negative breast cancer. Sacituzumab govitecan-hziy is an antibody-drug conjugate that combines a humanized monoclonal antibody, which targets the human trophoblast cell-surface antigen 2 (Trop-2), with SN-38, which is conjugated to the antibody by a cleavable linker. Sacituzumab govitecan-hziy enables delivery of high concentrations of SN-38 to tumors.

METHODS

We conducted a phase 1/2 single-group, multicenter trial involving patients with advanced epithelial cancers who received sacituzumab govitecan-hziy intravenously on days 1 and 8 of each 21-day cycle until disease progression or unacceptable toxic effects. A total of 108 patients received sacituzumab govitecan-hziy at a dose of 10 mg per kilogram of body weight after receiving at least two previous anticancer therapies for metastatic triple-negative breast cancer. The end points included safety; the objective response rate (according to Response Evaluation Criteria in Solid Tumors, version 1.1), which was assessed locally; the duration of response; the clinical benefit rate (defined as a complete or partial response or stable disease for at least 6 months); progression-free survival; and overall survival. Post hoc analyses determined the response rate and duration, which were assessed by blinded independent central review.

RESULTS

The 108 patients with triple-negative breast cancer had received a median of 3 previous therapies (range, 2 to 10). Four deaths occurred during treatment; 3 patients (2.8%) discontinued treatment because of adverse events. Grade 3 or 4 adverse events (in ≥10% of the patients) included anemia and neutropenia; 10 patients (9.3%) had febrile neutropenia. The response rate (3 complete and 33 partial responses) was 33.3% (95% confidence interval [CI], 24.6 to 43.1), and the median duration of response was 7.7 months (95% CI, 4.9 to 10.8); as assessed by independent central review, these values were 34.3% and 9.1 months, respectively. The clinical benefit rate was 45.4%. Median progression-free survival was 5.5 months (95% CI, 4.1 to 6.3), and overall survival was 13.0 months (95% CI, 11.2 to 13.7).

CONCLUSIONS

Sacituzumab govitecan-hziy was associated with durable objective responses in patients with heavily pretreated metastatic triple-negative breast cancer. Myelotoxic effects were the main adverse reactions. (Funded by Immunomedics; IMMU-132-01 ClinicalTrials.gov number, NCT01631552.).

Abstract P2-11-01: Safety and efficacy of sacituzumab govitecan (anti-Trop-2-SN-38 antibody-drug conjugate) as ≥3rd-line therapeutic option for treatment-refractory HER2-negative metastatic breast cancer (HER2Neg mBC)

Background: Sacituzumab govitecan is an antibody-drug conjugate consisting of SN-38, the active metabolite of irinotecan, conjugated to a humanized mAb targeting Trop-2 (trophoblastic antigen-2), which is highly expressed in many epithelial cancers. A phase I/II basket trial (NCT01631552) investigated its activity in patients (pts) with advanced epithelial cancers. Herein, we summarize pooled safety and efficacy findings in 162 pts with HER2-negative metastatic breast cancer (mBC) accrued between 7/2013 and 6/2017 who received at least 2 prior therapies for metastatic disease and were treated with sacituzumab govitecan at the 10 mg/kg dose level.

Methods: Patients with triple-negative (N=108) and patients with hormone-receptor positive (N=54) mBC received 10 mg/kg sacituzumab govitecan on days 1 & 8 of a 21-day cycle continued until progression or unacceptable toxicity. All pts had measurable disease by CT or MRI. Efficacy was assessed locally by RECIST 1.1 including overall response rate (ORR) and Kaplan-Meier estimates of duration of response (DOR), progression-free survival (PFS) and overall survival (OS). Adverse events (AE) were evaluated according to CTCAE v4.0

Results: The patient cohort (161 female /1 male; median age 55 yrs, range 31-80) received a median of 4 prior therapies for metastatic disease (range 2-17), with prior chemotherapy agents in the metastatic setting including taxane (68%), capecitabine (60%), platinum (59%), gemcitabine (44%), eribulin (41%), and anthracycline (38%). 77 pts have died, with 57 in long-term follow-up and 28 still on treatment at data cutoff. The median number of administered sacituzumab govitecan doses was 14 (range 1-88). Treatment was generally well tolerated. 29% of pts had dose reductions, 3% discontinued treatment due to drug-related AEs, and there were no treatment-related deaths. Based on currently available AE data, grade ≥ 3 toxicity included neutropenia (43%), anemia (9.5%), diarrhea (7.0%) and febrile neutropenia (6.3%). For the TNBC subgroup, with a median follow-up of 9.3 months, the ORR was 33% (3 CRs + 33 PRs /108) with a median DOR of 8.3 months (95% CI: 4.8 – 11.6). For the ER+ subgroup, with a median follow-up of 10.0 months, the ORR was 31% (17 PRs/54) with a median DOR of 7.4 months (95% CI: 4.4 – 18.3). The combined HER2Neg ORR was 33% (3 CRs+50 PRs/162), with a median DOR of 8.3 months (95% CI: 4.9 - 10.8), PFS of 5.6 months (95% CI: 5.1 – 6.9) and OS of 13.0 months (95% CI: 11.5 - 15.0). The ORR was comparable for pts ≤ 50 yrs. old [32.2% (19/59)] vs. > 50 yrs old [33.0% (34/103)] and little different for pts with 2 prior therapies [35.4% (17/48)] vs. >2 prior therapies [31.6% (36/114)].

Conclusions: Monotherapy with sacituzumab govitecan was well tolerated with a manageable safety profile, and achieved a 30+% objective response rate among heavily pre-treated patients with HER2-negative metastatic breast cancer regardless of ER status.

Citation Format: Kalinsky K, Isakoff SJ, Tolaney SM, Juric D, Mayer IA, Vahdat LT, Diamond JR, O'Shaughnessy J, Moroose RL, Santin AD, Shah NC, Abramson V, Goldenberg DM, Sharkey RM, Washkowitz SA, Wegener WA, Iannone R, Bardia A. Safety and efficacy of sacituzumab govitecan (anti-Trop-2-SN-38 antibody-drug conjugate) as ≥3rd-line therapeutic option for treatment-refractory HER2-negative metastatic breast cancer (HER2Neg mBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-11-01.

A phase 1 study of oral ridaforolimus in pediatric patients with advanced solid tumors

Purpose

Ridaforolimus is an investigational, potent, selective mTOR inhibitor. This study was conducted to determine the recommended phase 2 dose (RP2D), maximum tolerated dose, safety, pharmacokinetics, and antitumor activity of oral ridaforolimus in children with advanced solid tumors.

Experimental Design

In this phase 1, multicenter, open-label study in children aged 6 to <18 years with advanced solid tumors, ridaforolimus was administered orally for 5 consecutive days/week in 28-day cycles until progression, unacceptable toxicity, or consent withdrawal. Dose started at 22 mg/m² and increased to 28 mg/m² and 33 mg/m², followed by expansion at the RP2D.

Results

Twenty patients were treated; 18 were evaluable for dose-limiting toxicities. One dose-limiting toxicity (grade 3 increased alanine aminotransferase) occurred in 1 patient at 33 mg/m². Dose escalation concluded at 33 mg/m²; the maximum tolerated dose was not determined. The most common treatment-related adverse events (frequency ≥40%) were manageable grade 1–2 stomatitis, thrombocytopenia, hypertriglyceridemia, increased alanine aminotransferase, fatigue, hypercholesterolemia, anemia, and increased aspartate aminotransferase. Ridaforolimus exposure at 28 mg/m² and 33 mg/m² exceeded adult target levels. The RP2D for oral ridaforolimus in children was defined as 33 mg/m². Four patients received at least 4 cycles; 2 with pineoblastoma and diffuse intrinsic pontine glioma had stable disease for 12 and 46 cycles, respectively.

Conclusions

Ridaforolimus is orally bioavailable and well tolerated in children with advanced solid tumors. The RP2D (33 mg/m², 5 days/week) exceeds the adult RP2D. The favorable toxicity and pharmacokinetic profiles may allow for combination therapy, a promising therapeutic option in pediatric malignancies.

Blood Aspergillus RNA is a promising alternative biomarker for invasive aspergillosis

A critical challenge for the successful application of antifungal therapies for invasive aspergillosis (IA) is a lack of reliable biomarkers to assess early treatment response. Patients with proven or probable IA were prospectively enrolled, and serial blood samples were collected at 8 specified time points during 12-week antifungal therapy. Total nucleic acid was extracted from 2.5 ml blood and tested for Aspergillus-specific RNA by a pan-Aspergillus real-time nucleic acid sequence-based amplification (NASBA) assay. Serum 1, 3-β-D-glucan (BG) and galactomannan (GM) were measured in parallel. Clinical outcome was evaluated at 6 and 12 weeks. Overall, 48/328 (14.6%) blood samples from 29/46 (63%) patients had positive NASBA detection at baseline and/or some point during the study. Positive NASBA results during the first 4 and 6 weeks of treatment are significantly associated with the 12-week outcome. Blood RNA load change during weeks 4-6 may be informative to predict outcome at 12 weeks. While independent of serum GM, the kinetic change of circulating Aspergillus RNA appears to be well correlated with that of BG on some patient individuals. Monitoring blood Aspergillus RNA during the first 4-6 weeks of antifungal treatment may help assess therapeutic response. Combination of circulating Aspergillus RNA and BG may be a useful adjunct to assess response.

Phase 1 study of dalotuzumab monotherapy and ridaforolimus-dalotuzumab combination therapy in paediatric patients with advanced solid tumours

AIM

Dalotuzumab is a highly specific, humanised immunoglobulin G1 monoclonal antibody against insulin-like growth factor receptor 1. This multicenter phase 1 study (NCT01431547) explored the safety and pharmacokinetics of dalotuzumab monotherapy (part 1) and the combination of dalotuzumab with the mammalian target of rapamycin inhibitor ridaforolimus (part 2) in paediatric patients with advanced solid tumours.

METHODS

Dalotuzumab was administered intravenously every 3 weeks starting at 900 mg/m(2) and escalating to 1200 and 1500 mg/m(2). Combination therapy included intravenous dalotuzumab at the defined single-agent recommended phase 2 dose (RP2D) and oral ridaforolimus 28 mg/m(2) daily (days 1-5), repeated weekly. Pharmacokinetic studies were performed to evaluate the mean serum trough dalotuzumab concentration, which guided the RP2D.

RESULTS

Twenty-four patients were enrolled (part 1, n = 20; part 2, n = 4). No dose-limiting toxicities were observed in patients receiving dalotuzumab alone. One patient experienced dose-limiting stomatitis in the combination arm. Pharmacokinetic data showed dose-dependent increases in exposure (area under the curve from zero to infinity [AUC0-∞]) (87,900, 164,000, and 186,000 h*mg/ml for the 900, 1200, and 1500 mg/m(2) dose levels, respectively), maximum serum concentration (Cmax) (392, 643, and 870 mg/ml), and serum trough concentration (Ctrough) (67.1, 71.6, and 101 mg/ml). The mean half-life was 265, 394, and 310 h, respectively. Dalotuzumab pharmacokinetics were not affected by coadministration with ridaforolimus. One of six patients with Ewing sarcoma had confirmed partial response to dalotuzumab monotherapy at 900 mg/m(2). Time to response was 41 d, and progression occurred at 126 d.

CONCLUSION

Dalotuzumab was well tolerated in paediatric patients with advanced solid malignancies. The RP2D of dalotuzumab is 900 mg/m(2) (ClinicalTrials.gov identifier: NCT01431547, Protocol PN062).

Correlation between Circulating Fungal Biomarkers and Clinical Outcome in Invasive Aspergillosis

Objective means are needed to predict and assess clinical response in patients treated for invasive aspergillosis (IA). We examined whether early changes in serum galactomannan (GM) and/or β-D-glucan (BDG) can predict clinical outcomes. Patients with proven or probable IA were prospectively enrolled, and serial GM and BDG levels and GM optical density indices (GMI) were calculated twice weekly for 6 weeks following initiation of standard-of-care antifungal therapy. Changes in these biomarkers during the first 2 and 6 weeks of treatment were analyzed for associations with clinical response and survival at weeks 6 and 12. Among 47 patients with IA, 53.2% (25/47) and 65.9% (27/41) had clinical response by weeks 6 and 12, respectively. Changes in biomarkers during the first 2 weeks were associated with clinical response at 6 weeks (GMI, P = 0.03) and 12 weeks (GM+BDG composite, P = 0.05; GM, P = 0.04; GMI, P = 0.02). Changes in biomarkers during the first 6 weeks were also associated with clinical response at 6 weeks (GM, P = 0.05; GMI, P = 0.03) and 12 weeks (BDG+GM, P = 0.02; GM, P = 0.02; GMI, P = 0.01). Overall survival rates at 6 weeks and 12 weeks were 87.2% (41/47) and 79.1% (34/43), respectively. Decreasing biomarkers in the first 2 weeks were associated with survival at 6 weeks (BDG+GM, P = 0.03; BDG, P = 0.01; GM, P = 0.03) and at 12 weeks (BDG+GM, P = 0.01; BDG, P = 0.03; GM, P = 0.01; GMI, P = 0.007). Similar correlations occurred for biomarkers measured over 6 weeks. Patients with negative baseline GMI and/or persistently negative GMI during the first 2 weeks were more likely to have CR and survival. These results suggest that changes of biomarkers may be informative to predict and/or assess response to therapy and survival in patients treated for IA.

Phase I Study of Pembrolizumab (MK-3475; Anti-PD-1 Monoclonal Antibody) in Patients with Advanced Solid Tumors

PURPOSE

This phase I study evaluated the safety, maximum tolerated dose, antitumor activity, and pharmacokinetics and pharmacodynamics of pembrolizumab in patients with advanced solid tumors.

EXPERIMENTAL DESIGN

In a 3 + 3 dose escalation study, 10 patients received pembrolizumab 1, 3, or 10 mg/kg intravenously every 2 weeks until progression or intolerable toxicity. Seven additional patients received 10 mg/kg every 2 weeks. Thirteen patients participated in a 3-week intrapatient dose escalation (dose range, 0.005-10 mg/kg) followed by 2 or 10 mg/kg every 3 weeks. Tumor response was assessed by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.

RESULTS

No dose-limiting toxicities were observed. Maximum administered dose was 10 mg/kg every 2 weeks. One patient with melanoma and one with Merkel cell carcinoma experienced complete responses of 57 and 56+ weeks' duration, respectively. Three patients with melanoma experienced partial responses. Fifteen patients with various malignancies experienced stable disease. One patient died of cryptococcal infection 92 days after pembrolizumab discontinuation, following prolonged corticosteroid use for grade 2 gastritis considered drug related. Pembrolizumab exhibited pharmacokinetic characteristics typical of humanized monoclonal antibodies. Maximum serum target engagement was reached with trough levels of doses greater than or equal to 1 mg/kg every 3 weeks. Mechanism-based translational models with a focus on intratumor exposure prediction suggested robust clinical activity would be observed at doses ≥2 mg/kg every 3 weeks.

CONCLUSIONS

Pembrolizumab was well tolerated and associated with durable antitumor activity in multiple solid tumors. The lowest dose with full potential for antitumor activity was 2 mg/kg every 3 weeks.

Anti-programmed-death-receptor-1 treatment with pembrolizumab in ipilimumab-refractory advanced melanoma: a randomised dose-comparison cohort of a phase 1 trial

BACKGROUND

The anti-programmed-death-receptor-1 (PD-1) antibody pembrolizumab has shown potent antitumour activity at different doses and schedules in patients with melanoma. We compared the efficacy and safety of pembrolizumab at doses of 2 mg/kg and 10 mg/kg every 3 weeks in patients with ipilimumab-refractory advanced melanoma.

METHODS

In an open-label, international, multicentre expansion cohort of a phase 1 trial, patients (aged ≥18 years) with advanced melanoma whose disease had progressed after at least two ipilimumab doses were randomly assigned with a computer-generated allocation schedule (1:1 final ratio) to intravenous pembrolizumab at 2 mg/kg every 3 weeks or 10 mg/kg every 3 weeks until disease progression, intolerable toxicity, or consent withdrawal. Primary endpoint was overall response rate (ORR) assessed with the Response Evaluation Criteria In Solid Tumors (RECIST, version 1.1) by independent central review. Analysis was done on the full-analysis set (all treated patients with measurable disease at baseline). This study is registered with ClinicalTrials.gov, number NCT01295827.

FINDINGS

173 patients received pembrolizumab 2 mg/kg (n=89) or 10 mg/kg (n=84). Median follow-up duration was 8 months. ORR was 26% at both doses--21 of 81 patients in the 2 mg/kg group and 20 of 76 in the 10 mg/kg group (difference 0%, 95% CI -14 to 13; p=0·96). Treatment was well tolerated, with similar safety profiles in the 2 mg/kg and 10 mg/kg groups and no drug-related deaths. The most common drug-related adverse events of any grade in the 2 mg/kg and 10 mg/kg groups were fatigue (29 [33%] vs 31 [37%]), pruritus (23 [26%] vs 16 [19%]), and rash (16 [18%] vs 15 [18%]). Grade 3 fatigue, reported in five (3%) patients in the 2 mg/kg pembrolizumab group, was the only drug-related grade 3 to 4 adverse event reported in more than one patient.

INTERPRETATION

The results suggest that pembrolizumab at a dose of 2 mg/kg or 10 mg/kg every 3 weeks might be an effective treatment in patients for whom there are few effective treatment options.

FUNDING

Merck Sharp and Dohme.

Efficacy and safety of the anti-PD-1 monoclonal antibody MK-3475 in 411 patients (pts) with melanoma (MEL)

LBA9000^

Background: The humanized monoclonal IgG4 anti-PD-1 antibody MK-3475 has demonstrated durable antitumor activity in MEL and NSCLC. We evaluated MK-3475 efficacy and safety in a pooled analysis of 411 MEL pts. Methods: A nonrandomized cohort of ipilimumab-naive (IPI-N) and IPI-treated (IPI-T) pts treated with MK-3475 10 mg/kg Q2W, 10 mg/kg Q3W, or 2 mg/kg Q3W and randomized cohorts of IPI-N and IPI-T pts treated with 2 Q3W or 10 Q3W were included. Response was assessed every 12 wk by RECIST 1.1 by independent central review and by immune-related response criteria (irRC) by investigator. Results: 162 pts were treated at 2 Q3W, 192 at 10 Q3W, and 57 at 10 Q2W. 190 pts were IPI-N and 221 were IPI-T. As of the 10/18/2013 cutoff, all pts had ≥6 mo follow-up and >75% had ≥9 mo follow-up. Among the 365 pts with measurable disease at baseline, ORR by RECIST was 40% (95% CI 32%-48%) in IPI-N and 28% (95% CI 22%-35%) in IPI-T pts. Responses were durable (88% ongoing at analysis). Median PFS by RECIST was 24 wk in IPI-N and 23 wk in IPI-T pts. Median OS was not reached, with 1-y OS of 71% in all pts. Benefit was observed by both RECIST and irRC at all doses and schedules in IPI-N and IPI-T pts (Table). MK-3475 demonstrated activity in all major subgroups irrespective of ECOG PS, LDH levels, BRAFmutation, M stage, and number and type of prior therapy. Overall, 12% of pts experienced drug-related grade 3/4 AEs and 4% discontinued due to a drug-related AE. There were no drug-related deaths. Conclusions: MK-3475 showed durable responses and a manageable safety profile across dose and schedules in IPI-N and IPI-T MEL pts. The observed efficacy and safety suggest MK-3475 may be an appropriate treatment for all pts with MEL. Clinical trial information: NCT01295827. [Table: see text]

Repeatability of quantitative FDG-PET/CT and contrast-enhanced CT in recurrent ovarian carcinoma: test-retest measurements for tumor FDG uptake, diameter, and volume

PURPOSE

Repeatability of baseline FDG-PET/CT measurements has not been tested in ovarian cancer. This dual-center, prospective study assessed variation in tumor 2[18F]fluoro-2-deoxy-D-glucose (FDG) uptake, tumor diameter, and tumor volume from sequential FDG-PET/CT and contrast-enhanced computed tomography (CECT) in patients with recurrent platinum-sensitive ovarian cancer.

EXPERIMENTAL DESIGN

Patients underwent two pretreatment baseline FDG-PET/CT (n = 21) and CECT (n = 20) at two clinical sites with different PET/CT instruments. Patients were included if they had at least one target lesion in the abdomen with a standardized uptake value (SUV) maximum (SUVmax) of ≥ 2.5 and a long axis diameter of ≥ 15 mm. Two independent reading methods were used to evaluate repeatability of tumor diameter and SUV uptake: on site and at an imaging clinical research organization (CRO). Tumor volume reads were only performed by CRO. In each reading set, target lesions were independently measured on sequential imaging.

RESULTS

Median time between FDG-PET/CT was two days (range 1-7). For site reads, concordance correlation coefficients (CCC) for SUVmean, SUVmax, and tumor diameter were 0.95, 0.94, and 0.99, respectively. Repeatability coefficients were 16.3%, 17.3%, and 8.8% for SUVmean, SUVmax, and tumor diameter, respectively. Similar results were observed for CRO reads. Tumor volume CCC was 0.99 with a repeatability coefficient of 28.1%.

CONCLUSIONS

There was excellent test-retest repeatability for FDG-PET/CT quantitative measurements across two sites and two independent reading methods. Cutoff values for determining change in SUVmean, SUVmax, and tumor volume establish limits to determine metabolic and/or volumetric response to treatment in platinum-sensitive relapsed ovarian cancer.

Abstract P4-01-11: Limits of [18F]-FLT PET as a clinical biomarker of proliferation in breast cancer

Background:

Imaging biomarkers of cellular division offer promise as non-invasive measures of tumor response. 3’-deoxy-3’[18F]-fluorothymidine ([18F]-FLT) positron emission tomography (PET) imaging generally correlates with pathology-based measurements of cancer proliferation, especially the Ki67 score. Though clinical studies have associated changes in [18F]-FLT uptake with therapeutic response, clinical studies validating its ability to assess cell proliferation are comparatively lacking. The goal of this study was to determine quantitative relationships between [18F]-FLT compared with molecular and cellular metrics of proliferation during treatment for locally advanced breast cancer (LABC).

Methods:

Baseline [18F]−FLT-PET scans were obtained prior to the initiation of chemotherapy for LABC from patients enrolled at several academic oncology study sites. MRI scans, and transmission CT scans were obtained. Core needle biopsies were obtained to determine Ki-67 indices using immuno-histochemistry and to assess an mRNA signature based measurement of proliferation. Prospectively specified quantitative relationships between PET, Ki67 immunohistochemistry and the mRNA signature were evaluated using image-matched tumor specimens. Correlations between volumetric MRI changes and pathologic responses were evaluated in a post-hoc exploratory analysis.

Results:

Motivated by the hypothesis that effective chemotherapies should decrease tumor cell proliferation, FLT-PET was compared with biomarkers of proliferation including Ki67 and the mRNA signature during neoadjuvant treatment for LABC. [18F]-FLT correlated both with the Ki67 labeling index (SUVmean r = 0.53) and with the proliferation signature (SUVmean r = 0.7), validating the principle of thymidine analogue imaging. However, variability in the [18F]-FLT PET and tumor cell proliferation measures likely contributed to correlations less than pre-specified target values considered appropriate for clinical use (r &gt; 0.78). Moreover, none of the proliferation biomarkers predicted pathologic complete responses at the end of neoadjuvant therapy ∼16 weeks after the 3 week response scan. In contrast, an evaluation of change in tumor volume measured by MRI after 3 weeks of therapy confirmed its superior ability to predict pCR and tumor re-staging.

Conclusion:

With large numbers of cancer drugs entering therapeutic pipelines, early efficacy measures remain critical for drug development. The 3-4 month neoadjuvant treatment paradigm for LABC offers unique opportunities for drug evaluation. Functional imaging using [18F]-FLT has been advanced as an assessor of cellular proliferation, potentially offering a non-invasive approach to response evaluation. While [18F]-FLT generally correlated with proliferation, its lack of association with patient responses likely limit its clinical utility. On the other hand, the predictive value of MRI offers unique opportunities for future trial designs and confirms previous reports (1).

1. N. M. Hylton et al., Locally advanced breast cancer: MR imaging for prediction of response to neoadjuvant chemotherapy. Radiology 263, 663 (2012).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-01-11.

(11)C-MK-8278 PET as a tool for pharmacodynamic brain occupancy of histamine 3 receptor inverse agonists

The histamine 3 (H3) receptor is a presynaptic autoreceptor in the central nervous system that regulates the synthesis and release of histamine and modulates the release of other major neurotransmitters. H3 receptor inverse agonists (IAs) may be efficacious in the treatment of various central nervous system disorders, including excessive daytime sleepiness, attention deficit hyperactivity disorder, Alzheimer disease, ethanol addiction, and obesity.

METHODS

Using PET and a novel high-affinity and selective radioligand (11)C-MK-8278, we studied the tracer biodistribution, quantification, and brain H3 receptor occupancy (RO) of MK-0249 and MK-3134, 2 potential IA drugs targeting cerebral H3 receptors, in 6 healthy male subjects (age, 19-40 y). The relationship among H3 IA dose, time on target, and peripheral pharmacokinetics was further investigated in 15 healthy male volunteers (age, 18-40 y) with up to 3 PET scans and 3 subjects per dose level.

RESULTS

The mean effective dose for (11)C-MK-8278 was 5.4 ± 1.1 μSv/MBq. Human brain kinetics showed rapid high uptake and fast washout. Binding potential values can be assessed using the pons as a reference region, with a test-retest repeatability of 7%. Drug RO data showed low interindividual variability per dose (mean RO SD, 2.1%), and a targeted 90% RO can be reached for both IAs at clinically feasible doses.

CONCLUSION

(11)C-MK-8278 is a useful novel PET radioligand for determination of human cerebral H3 receptor binding and allows highly reproducible in vivo brain occupancy of H3-targeting drugs, hereby enabling the evaluation of novel compounds in early development to select doses and schedules.

A phase I study of ridaforolimus (MK-8669) in pediatric patients with advanced solid tumors

10027

Background: Deregulation of the PI3K/AKT/mTOR signaling pathway occurs in many poor prognosis childhood malignancies and inhibition of this pathway is a promising novel therapeutic strategy. Ridaforolimus (MK-8669) is a highly selective orally bioavailable small molecule inhibitor of mTOR. This multi-centre, phase I dose escalation study of orally administered Ridaforolimus was designed to evaluate the maximum tolerated dose (MTD), safety profile, pharmacokinetic profile (PK), antitumor activity and pharmacodynamic (PD) biomarkers (phosphorylated Akt [pAkt] in platelet-rich plasma). Methods: Patients (pts) from 6 to <18 years (yrs) with advanced solid tumors were enrolled. Dose escalation was by a modified Toxicity Probability Intervals method (mTPI, Ji Y, et al. Clin Trials 2007) targeting a 30% dose limiting toxicity (DLT) ratio. Pts received 28 day cycles of Ridaforolimus (MK-8669), orally, five days out of seven. Dosing started at 22 mg/m2, escalated to 28 and 33 mg/m2, with an expansion cohort treated at the maximum administered dose. Results: 19 pts, age 8-17 (median 13.5 years), were enrolled and 18 treated from 6 international sites. Diagnoses included ependymoma (5), osteosarcoma (3), Ewings sarcoma (3) and other histologies (7). Four pts received dose level (DL) 1; 3 DL 2 and 11 DL 3. Pts received between 1-12+ courses. There was only one DLT (DL 2: grade 3 elevated alanine transaminase [ALT]) and no other grade 3-4 treatment-related toxicities. Preliminary analysis shows the most frequent drug-related adverse events were manageable grade 1-2 stomatitis (70.6%) and fatigue (52%). Dose escalation stopped at DL3 (33 mg/m2, 150% of the adult recommended phase 2 dose [RP2D]). There were no objective responses by RECIST1.1. Two pts remain on study, with continuing stable disease (pineoblastoma [12 courses], diffuse intrinsic pontine glioma [6 courses]). PK and PD analyses will be presented. Conclusions: Ridaforolimus is a safe and well tolerated, orally bioavailable mTOR inhibitor. The RP2D for Ridaforolimus in children is 33 mg/m2. Prolonged disease stabilization was observed in two patients. PK/PD data will provide further data to support the RP2D. Further combination studies are warranted. Clinical trial information: NCT01431547.

A phase I study of the anti-insulin like growth factor type 1 receptor (IGF-1R) antibody dalotuzumab in pediatric patients with advanced solid tumors

10026

Background: Insulin-like growth factor signaling plays an important role in several pediatric cancers. Dalotuzumab is a highly specific, humanized IgG1 monoclonal antibody against IGF-1R. This multicenter phase 1 study explored the safety and pharmacokinetics (PK) of dalotuzumab in pediatric patients with advanced solid tumors. Methods: Dalotuzumab was administered intravenously every 3 weeks. Dose-escalation was performed according to a modified Toxicity Probability Interval (mTPI) design starting at 900 mg/m2. The PK profile of dalotuzumab was evaluated with the primary goal of confirming that the Day 22 mean serum trough concentration exceeded 25 μg/mL. Results: 24 patients were enrolled and 20 treated (median age, 10.5 years; range, 3–17 years). Six patients had recurrent Ewing sarcoma. Patients received a median of 2 cycles (range, 1-10). No dose-limiting toxicity was observed in any of the three dose levels explored (900, 1200 and 1500 mg/m2). Main treatment-related toxicities were Grade 3 elevated transaminases. PK data showed dose dependent increases in AUC0-∞ (105,000, 164,000 and 281,000 hr*mg/mL, for the 900, 1200 and 1500 mg/m2 dose levels, respectively), Ctrough (65.2, 71.6, 148 mg/mL) and Cmax (559, 643, 888 mg/mL). The mean half-life was 247, 394 and 376 hours respectively. The Cmax exhibited mild variability (4.8-35% Coefficient of Variation), whereas variability was moderate to high on the Ctrough (39-200%), apparent t1/2 (28-154%), AUC0-∞ (29-106%) and clearance (52-161%). Except for one patient at the 1200 mg/m2 dose level, all patients met the PK target, a Ctrough of 25 μg/mL, suggesting 900 mg/m2as the recommended phase 2 dose (RP2D). One patient with Ewing sarcoma had a confirmed partial response; 2 patients with Ewing sarcoma and one with nephroblastoma had stable disease for at least 7, 5 and 6 months, respectively. Conclusions: Dalotuzumab is well tolerated in pediatric patients with advanced malignancies. The RP2D of 900 mg/m2 was chosen based on tolerability and PK parameters. Preliminary data confirm prior reports suggesting activity in Ewing sarcoma. Clinical trial information: NCT01431547.

Repeatability of edited lactate and other metabolites in astrocytoma at 3T

PURPOSE

To assess the repeatability of measurement of lactate and other metabolites in tumors using magnetic resonance spectroscopy (MRS).

MATERIALS AND METHODS

MRS with spectral editing for lactate was performed on 10 patients with astrocytoma (two Grade III, eight Grade IV) using an 8-channel receive coil at 3T. Lactate, lipid, choline, creatine, and N-acetyl aspartate (NAA) signals were measured in regions of tumor and contralateral white matter. Metabolites were quantified relative to unsuppressed water using LCModel fitting software.

RESULTS

The within-patient coefficients of variation were ≈16% (tumor lactate), 6%-8% (tumor choline and contralateral choline, creatine, and NAA), and 22% (tumor lipid). As expected due to their low concentration in normal tissue, lactate and lipid were not reliably detected in white matter but were found at high levels in most tumors. NAA and creatine were lower in tumors than in normal white matter, and choline varied between above- and below-normal values. No consistent short-term variation in metabolite levels was observed, despite differences in the time elapsed since administration of contrast agent.

CONCLUSION

MRS appears repeatable enough to provide longitudinal measures of metabolite content in tumors and contralateral tissue in the brain in vivo.

Pharmacodynamic evaluation of pCDC2 as the target engagement biomarker to assess activity of MK-1775 a Wee1 tyrosine kinase inhibitor

e13598

Background: Wee1 kinase regulates the G2 checkpoint through phosphorylation of CDC2. MK-1775 is a first-in-class inhibitor of Wee1, and thereby reduces pCDC2 levels relative to CDC2. pCDC2therefore can be used as a target engagement (TE) biomarker to assess activity of MK-1775. This was investigated in a phase I first-in-man clinical trial of MK-1775. Methods: This is a multicenter, open-label, non-randomized phase I dose escalation study in patients with locally advanced or metastatic solid tumors. MK-1775 was administered orally in escalating doses as monotherapy, and either single dose or multi-dose in combination with chemotherapy including cisplatin, carboplatin and gemcitabine. Serial skin biopsies were performed at baseline and either 8, 24 or 48 hours following MK-1775 administration and analyzed by IHC for CDC2 and pCDC2. Based on preclinical efficacy experiments, TE was defined as a decrease of pCDC2 of at least 50% (or fold change > 0.50) from pre- to post-dose MK-1775. Results: To date a total of 176 patients have received at least one dose of MK-1775 either as monotherapy or in combination (single or multi-dose MK-1775) with chemotherapy at doses ranging from 25 mg to 1300 mg to define maximum tolerated dose. Dose dependent decreases in pCDC2 were observed in skin biopsies between pre-dose and post-dose treatment in all treatment groups. TE with monotherapy was achieved at 325 mg. TE with multi-dose MK-1775 in combination with cisplatin and carboplatin were achieved at 125 mg BID and 225 mg BID. Gemcitabinecombination treatment is on-going. In contrast, chemotherapy alone resulted in an increase of pCDC2. Conclusions: Based on preclinical data, in this first-in-man clinical trial of MK-1775, we were able to demonstrate TE required for maximal efficacy at tolerable doses of MK-1775 either as a single agent or in combination with chemotherapy. [Table: see text]

FDG-PET and CT as early predictors of outcome in NSCLC patients treated with erlotinib

10573

Background: Tumor metabolism as assessed by FDG-PET is an early biomarker for clinical benefit in oncology. This multi-national study evaluated associations of changes in mean standardized uptake values (SUVmean) of FDG and tumor burden with disease control rates (DCR: CR+PR+SD), PFS and OS in 48 NSCLC patients (EGFR mutants or favorable clinical/demographic characteristics) treated with erlotinib. The primary hypothesis was that changes in SUVmean at day 8 predicted DCR. Methods: Patients were scanned by FDG-PET (twice pre-therapy, 1 and 3 weeks post-therapy) and CT (same as FDG-PET and every 6 weeks post-therapy until progression or death). Early response biomarkers included the decrease in SUVmean (DiSUV), sum of diameters (DiSOD) and sum of volumes (DiSOV). For the primary hypothesis, metabolic response (MR) was defined as a decrease of >2SD the variability between baseline PET scans (30%). Exploratory analyses of the biomarkers at various thresholds were performed. Results: The primary hypothesis was met: DCR was 34.6% (80% CI: 17.5%, 48.2%) higher in patients with a MR at day 8 (p = 0.033); the association was stronger for day 22. The table compares hazard ratios derived from the "optimal" % decrease (smallest upper 80% confidence limit) over the 10% to 50% (by 10%) range for all biomarkers and time points, by PFS and OS. Conclusions: FDG-PET was predictive for clinical responses after 8 days of treatment. Comparing all biomarkers, DiSOV had stronger associations than both DiSUV and DiSOD with PFS or OS. For NSCLC treated with erlotinib in this clinical context, the decrease in CT-based tumor volume may be a better early predictor of clinical outcome than FDG-based SUVmean. [Table: see text]

The effects of a novel histamine-3 receptor inverse agonist on essential tremor in comparison to stable levels of alcohol

Essential tremor (ET) is a common movement disorder. Animal studies show that histaminergic modulation may affect the pathological processes involved in the generation of ET. Histamine-3 receptor inverse agonists (H3RIA) have demonstrated attenuating effects on ET in the harmaline rat model. In this double-blind, three-way cross-over, single-dose, double-dummy study the effects of 25 mg of a novel H3RIA (MK-0249) and a stable alcohol level (0.6 g L(-1)) were compared with placebo, in 18 patients with ET. Tremor was evaluated using laboratory tremorography, portable tremorography and a clinical rating scale. The Leeds Sleep Evaluation Questionnaire (LSEQ) and a choice reaction time (CRT) test were performed to evaluate potential effects on sleep and attention, respectively. A steady state of alcohol significantly diminished tremor as assessed by laboratory tremorography, portable tremorography and clinical ratings compared with placebo. A high single MK-0249 dose was not effective in reducing tremor, but caused significant effects on the LSEQ and the CRT test. These results suggest that treatment with a single dose of MK-0249 does not improve tremor in alcohol-responsive patients with ET, whereas stable levels of alcohol as a positive control reproduced the commonly reported tremor-diminishing effects of alcohol.

AAML03P1, a pilot study of the safety of gemtuzumab ozogamicin in combination with chemotherapy for newly diagnosed childhood acute myeloid leukemia: a report from the Children's Oncology Group

BACKGROUND

The development of antigen-targeted therapies may provide additional options to improve outcomes in children with acute myeloid leukemia (AML). The Children's Oncology Group AAML03P1 trial sought to determine the safety of adding 2 doses of gemtuzumab ozogamicin, a humanized anti-CD33 antibody-targeted agent, to intensive chemotherapy during remission induction and postremission intensification for children with de novo AML.

METHODS

AAML03P1 enrolled 350 children with previously untreated AML. Patients with a matched family donor received 3 courses of chemotherapy followed by hematopoietic stem cell transplantation; those without a matched family donor received 5 courses of chemotherapy. Gemtuzumab ozogamicin 3 mg/m(2)/dose was administered on Day 6 of Course 1 and Day 7 of Course 4.

RESULTS

Toxicities observed in all courses of therapy were typical of AML chemotherapy regimens, with infection being most common. Patients achieved a complete remission rate of 83% after 1 course and 87% after 2 courses. The mortality rate was 1.5% after the first gemtuzumab ozogamicin-containing induction course and 2.6% after 2 induction courses. The 3-year event-free survival and overall survival rates were 53 ± 6% and 66 ± 5%, respectively.

CONCLUSIONS

This trial determined that it is safe and feasible to include gemtuzumab ozogamicin in combination with intensive chemotherapy. The survival rates compare favorably with the recently published results of clinical trials worldwide.

Abstract 26: Notch pathway inhibition with MK-0752 leads to dose- and time-dependent transcriptional alterations in proliferation, PI3K, and Wnt pathway genes in plucked human hair follicles

Introduction: Gamma-secretase inhibitors (GSIs) inhibit Notch signaling and have potential as cancer therapeutics. A clinical trial of the oral GSI MK-0752 was conducted in healthy subjects using transcriptional profiling of human plucked hair follicles (PHFs). Data from this study were analyzed using pre-specified gene signatures reflecting Notch, proliferation, and PI3K pathway activity. De novo signature analysis was performed to identify late patterns of transcriptional response. Procedures: A randomized, placebo-controlled (PBO) trial evaluated the effects of a single 350mg or 1000mg dose of MK-0752 on PHF gene expression in healthy males. Plasma and pooled PHFs were collected for PK and PD (mRNA profiling) analyses. Results: In addition to a significant decrease in a Notch signature score (NSS, primary endpoint) which was maximal at 8.5h and significant up to 96h following a single 1000mg dose of MK-0752 compared to PBO, in a post hoc analysis we saw a significant decrease in a 101-gene Growth Factor Signature (GFS) score associated with downregulation of PI3K pathway signaling (effect size = −1.02, p &lt; 0.001 1-sided) at 8.5h post-dose. In another post hoc analysis, we observed a significant suppression of a Proliferation Signature (PS) consisting of 50 cell cycle-associated genes (effect size = −0.57, p=0.016 1-sided) at 28.5h post-dose following a single 1000mg dose of MK-0752 compared to PBO. Dose- and time-dependent decreases were observed in both the GFS and the PS. To understand the compensatory transcriptional response at later time points, normalized data for each subject was compared to the corresponding time-point in the PBO-treated arm. In a training set, the paired t-test was used to identify 768 probes, representing genes that are strongly regulated (p &lt; 0.005) 48-hours after treatment with MK-0752. Composite biomarker characteristics (a one-arm score, two-arm score, and AUC for the signature score in treated versus PBO groups) were calculated in validation set. Analysis of the most regulated genes at 48-hours post-dose showed significant changes in Wnt signaling and epithelial/mesenchymal transition (EMT) genes. Conclusions: Human PHFs contain cells with intact Notch signaling responsive to MK-0752. Transient inhibition of Notch leads to dose-dependent decreases in Notch and PI3K pathway genes, followed by decreases in cell cycle genes. As MK-0752 is eliminated and intrinsic Notch signaling re-established, we saw dose- and time-dependent upregulation of EMT and Wnt signaling, along with genes involved in cell communication and adhesion. These findings provide important evidence for cross-talk between Notch and other pathways relevant to oncology. These findings substantiate the rationale for combining PI3K pathway agents (e.g., an AKT or mTOR inhibitor) with a GSI for treatment of cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 26.

Weighing the risks of G-CSF administration, leukopheresis, and standard marrow harvest: ethical and safety considerations for normal pediatric hematopoietic cell donors

BACKGROUND

Granulocyte colony stimulating factor (G-CSF) is used for collection of hematopoietic cells in most adult and a smaller but significant percentage of pediatric normal donor harvests. Short and long-term risks of G-CSF administration and leukopheresis are not well understood in the pediatric population.

PROCEDURE

Literature review including observations from the IBMTR, NMDP, EBMT, German Donor Registry, and the authors' work.

RESULTS

G-CSF causes temporary discomfort in a minority of younger donors. Rare serious side effects of G-CSF have yet to be reported in children. To date, an increase in hematological malignancies after short-term G-CSF use has not been detected in adult donors and no cases have been reported in children. Reported complications of leukopheresis in children are rare and minor, but donors <20 kg may be exposed to allogeneic blood products. Pediatric aged donors vary widely in their ability to assent or consent to the risks of a donation procedure. There are key regulations and ethical imperitives, which must be addressed in deciding which donation procedures are appropriate for minors.

CONCLUSIONS

While short term administration of G-CSF and leukopheresis appear to be safe and effective procedures when used to assist in collection of a hematopoietic cell graft from a normal pediatric donor, institutions adding or substituting one or both of these procedures for standard marrow donation must decide whether the donor should be considered a research subject, and if so, whether the new procedures are a minor increase over minimal risk. Because these procedures are being performed on and off study at many pediatric centers, a comprehensive study addressing donor safety could help clarify risks of rare adverse events.

Tissue typing for hematopoietic cell transplantation: newer techniques and newer antigens for which cross-matching is helpful

Refinements in human leukocyte antigen (HLA) typing techniques for hematopoietic cell transplantation (HCT) have permitted a more precise assessment of donor-recipient histocompatibility, which has impacted transplantation outcomes. More recently, differences in transplant outcomes associated with killer immunoglobulin-like receptor compatibility have emphasized the potential importance of natural killer (NK) cell typing in HCT. This article reviews the current state of the art for HCT donor selection based on both HLA and NK cell typing.

Unrelated donor bone marrow transplantation for children with severe aplastic anemia: minimal GVHD and durable engraftment with partial T cell depletion

Both increased graft rejection and increased graft vs host disease (GVHD) remain obstacles to success for unrelated donor (URD) BMT for patients with SAA. Partial T cell depletion (PTCD) may decrease the risk of severe GVHD, while still maintaining sufficient donor T lymphocytes to ensure engraftment. We report on 12 patients with SAA who underwent PTCD URD BMT. All patients had failed medical therapy or relapsed following initial responses, and were transfusion dependent. The median age was 6 years, and there were five males. Donors were matched for four patients, and mismatched for eight. All patients received total body irradiation with either Ara-C or thiotepa and cyclophosphamide. PTCD was accomplished using monoclonal antibody T10B9 or OKT3 and complement. All patients engrafted, with a median time of 18 days to ANC >500. Only one patient had greater than grade II acute GVHD; two patients had limited and one patient extensive chronic GVHD. Nine patients are alive and transfusion independent at a median months post BMT. Three patients died from infection or renal failure. This series suggests that an aggressive immunosuppressive conditioning regimen with PTCD results in successful engraftment and minimal GVHD in pediatric patients with SAA, even with HLA mismatched donors.

Pulmonary hypertension complicating bone marrow transplantation for idiopathic myelofibrosis

Idiopathic myelofibrosis is a rare hematologic disorder that is occasionally associated with pulmonary hypertension and has been cured with bone marrow transplantation (BMT). Most cases occur in older adults, but children with similar clinical and pathologic findings have been described. The authors describe a critically ill male infant with idiopathic myelofibrosis and subtle findings suggestive of pulmonary hypertension who was treated with BMT after failing to respond to chemotherapy. After BMT, the patient's clinical course improved in all respects, but he ultimately died of progressive pulmonary hypertension.

Results of minimally toxic nonmyeloablative transplantation in patients with sickle cell anemia and beta-thalassemia

We describe previously transfused patients with sickle cell disease (n = 6) and thalassemia (n = 1) who received nonmyeloablative hematopoietic stem cell transplantation (HCT) to induce stable (full or partial) donor engraftment. Patients were 3 to 20 years (median, 9 years) old. All 7 received pretransplantation fludarabine and 200 cGy of total body irradiation; 2 patients also received horse antithymocyte globulin. Patients received bone marrow (n = 6) or peripheral blood stem cells (n = 1) from HLA-identical siblings, followed by a combination of mycophenolate mofetil and cyclosporine or tacrolimus for postgrafting immunosuppression. After nonmyeloablative HCT, absolute neutrophil counts were <0.5 x 10(9)/L and <0.2 x 10(9)/L for a median of 5 days (range, 0-13 days) and 0 days (range 0-13 days), respectively. A median of 0 (range, 0-9) platelet transfusions were administered. No grade IV nonhematologic toxicities were observed. One patient experienced grade II acute graft-versus-host disease. Two months after transplantation, 6 of 7 patients had evidence of donor chimerism (range, 25%-85%). Independent of red blood cell transfusions, these 6 patients initially had increased total hemoglobin and hemoglobin A concentrations and a reduction of reticulocytosis and transfusion requirements. There were no complications attributable to sickle cell disease during the interval of transient mixed chimerism. However, after posttransplantation immunosuppression was tapered, there was loss of the donor graft, and all patients experienced autologous hematopoietic recovery and disease recurrence. One patient did not engraft. The duration of transient mixed chimerism ranged from 97 to 441 days after transplantation in patients 4 and 6, respectively, and persisted until immunosuppressive drugs were discontinued after transplantation. In summary, the nonmyeloablative HCT regimens described here produced minimal toxicity and resulted in transient donor engraftment in 6 of 7 patients with hemoglobinopathies. Although complications from the underlying hemoglobinopathies did not occur during the period of mixed chimerism, these results suggest that stable (full or partial) donor engraftment after nonmyeloablative HCT is more difficult to achieve among immunocompetent pediatric patients with hemoglobinopathies than among adults with hematologic malignancies, perhaps in part because recipients may have been sensitized to minor histocompatibility antigens of their donor by preceding blood transfusions.

Posttransplantation cyclophosphamide facilitates engraftment of major histocompatibility complex-identical allogeneic marrow in mice conditioned with low-dose total body irradiation

Cyclophosphamide (Cy) has been studied extensively for its immunosuppressive properties and is frequently combined with total body irradiation (TBI) as conditioning prior to HLA-identical allogeneic blood or marrow transplantation (alloBMT) in humans. Because Cy is most effective at suppressing host-versus-graft reactions when the drug is given after the transplantation (Mayumi H et al. Transplant Proc. 1986;18:363-369), we investigated whether posttransplantation Cy could prevent rejection of allogeneic marrow in mice conditioned with low-dose TBI. In a mouse model, posttransplantation Cy reduced the dose of TBI required from 500 cGy to < or = 200 cGy for the engraftment of 10 million major histocompatibility complex (MHC)-identical marrow cells in 100% of recipients. In animals conditioned with low-dose TBI and posttransplantation Cy, donor chimerism was proportional to the dose of TBI, was present in multiple hematopoietic lineages, and was associated with the indefinite survival of donor-strain skin grafts. In contrast, animals conditioned with either TBI alone or posttransplantation Cy alone failed to achieve engraftment after alloBMT and contained antidonor cytotoxic T-cells. Although <5% donor chimerism could be induced without TBI by transplanting > or = 50 million MHC-identical cells and administering posttransplantation Cy, the addition of low-dose TBI reduced the dose of donor cells required for alloengraftment and increased long-term donor chimerism to >50%. These data demonstrate that low-dose TBI and posttransplantation Cy cooperate to prevent graft rejection following the transplantation of standard doses of MHC-identical marrow cells.

Hematology Grants Workshop

Uppermost among the many concerns of young researchers is acquiring funding for beginning a career as a clinician-scientist. This chapter is targeted specifically at those individuals considering an academic physician-scientist career and those on the verge of becoming independent researchers.

In Section I, Drs. Poncz and Iannone discuss the Mentored Career Development Award (K08). They summarize the application process, highlighting the critical components of a successful application and what the review process entails.

In Section II, Dr. Werner discusses what applicants need to know about the NIH Institutes’ program, review, and grants management function; the different NIH staff whom applicants should contact during the various stages of the grants process; and the important sections and key phrases in NIH Program Announcements for career development awards.

Durable engraftment of major histocompatibility complex-incompatible cells after nonmyeloablative conditioning with fludarabine, low-dose total body irradiation, and posttransplantation cyclophosphamide

Treatment of leukemia by myeloablative conditioning and transplantation of major histocompatibility complex (MHC)-mismatched stem cells is generally avoided because of the high risk of graft rejection or lethal graft-versus-host disease (GVHD). This study shows that MHC-incompatible cells can engraft stably after nonmyeloablative conditioning with immunosuppressive chemotherapy and low-dose total body irradiation (TBI). Long-term mixed hematopoietic chimerism, clonal deletion of donor-reactive T cells, and bidirectional cytotoxic T-cell tolerance were achieved by transplanting MHC-mismatched marrow cells into recipients conditioned with pretransplantation fludarabine or cyclophosphamide (Cy), 50 to 200 cGy TBI on day -1, and Cy 200 mg/kg intraperitoneally on day 3. In this model, long-term donor chimerism was proportional to the dose of TBI or donor marrow cells. Pretransplantation fludarabine and posttransplantation Cy were both required for alloengraftment, but the drugs had additional effects. For example, fludarabine sensitized host stem cells to the toxicity of TBI, because animals conditioned with both agents had higher chimerism than animals conditioned with TBI alone (P <.05). Also, posttransplantation Cy attenuated lethal and nonlethal GVH reactions, because F(1) recipients of host-reactive, parental spleen cells survived longer (P <.05) and had lower donor cell chimerism (P <.01) if they received posttransplantation Cy than if they did not. Finally, delayed infusions of donor lymphocytes into mixed chimeras prolonged survival after leukemia challenge (P <.0001) without causing lethal GVHD. These results indicate that stable engraftment of MHC-incompatible cells can be induced after fludarabine-based, nonmyeloablative conditioning and that it serves as a platform for adoptive immunotherapy with donor lymphocyte infusions.