Bryan R. Leigh

Biodistribution and dosimetry results from a phase III prospectively randomized controlled trial of Zevalin radioimmunotherapy for low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma.

UNLABELLED Radiation dosimetry studies were performed in patients with non-Hodgkins lymphoma (NHL) treated with 90Y Zevalin (90yttrium ibritumomab tiuxetan, IDEC-Y2B8) on a Phase III open-label prospectively randomized multicenter trial. The trial was designed to evaluate the efficacy and safety of 90Y Zevalin radioimmunotherapy compared to rituximab (Rituxan, MabThera) immunotherapy for patients with relapsed or refractory low-grade, follicular, or transformed NHL. An important secondary objective was to determine if radiation dosimetry prior to 90Y Zevalin administration is required for safe treatment in this patient population. METHODS Patients randomized into the Zevalin arm were given a tracer dose of 5 mCi (185 MBq) (111)In Zevalin (111indium ibritumomab tiuxetan) on Day 0, evaluated with dosimetry, and then administered a therapeutic dose of 0.4 mCi/kg (15 MBq/kg) 90Y Zevalin on Day 7. Both Zevalin doses were preceded by an infusion of 250 mg/m(2) rituximab to clear peripheral B-cells and improve Zevalin biodistribution. Following administration of (111)In Zevalin, serial anterior and posterior whole-body scans were acquired and blood samples were obtained. Residence times for 90Y were estimated for major organs, and the MIRDOSE3 computer software program was used to calculate organ-specific and total body radiation absorbed dose. Patients randomized into the rituximab arm received a standard course of rituximab immunotherapy (375 mg/m(2) weekly x 4). RESULTS In a prospectively defined 90 patient interim analysis, the overall response rate was 80% for Zevalin vs. 44% for rituximab. For all patients with Zevalin dosimetry data (N=72), radiation absorbed doses were estimated to be below the protocol-defined upper limits of 300 cGy to red marrow and 2000 cGy to normal organs. The median estimated radiation absorbed doses were 71 cGy to red marrow (range: 18-221 cGy), 216 cGy to lungs (94-457 cGy), 532 cGy to liver (range: 234-1856 cGy), 848 cGy to spleen (range: 76-1902 cGy), 15 cGy to kidneys (0.27-76 cGy) and 1484 cGy to tumor (range: 61-24274 cGy). Toxicity was primarily hematologic, transient, and reversible. The severity of hematologic nadir did not correlate with estimates of effective half-life (half-life) or residence time of 90Y in blood, or radiation absorbed dose to the red marrow or total body. CONCLUSION 90Y Zevalin administered to NHL patients at non-myeloablative maximum tolerated doses delivers acceptable radiation absorbed doses to uninvolved organs. Lack of correlation between dosimetric or pharmacokinetic parameters and the severity of hematologic nadir suggest that hematologic toxicity is more dependent on bone marrow reserve in this heavily pre-treated population. Based on these findings, it is safe to administer 90Y Zevalin in this defined patient population without pre-treatment (111)In-based radiation dosimetry.

A Phase I First-in-Human Study of TRC105 (Anti-Endoglin Antibody) in Patients with Advanced Cancer

Purpose: TRC105 is a chimeric IgG1 monoclonal antibody that binds CD105 (endoglin). This first-in-human, phase I, open-label study assessed safety, pharmacokinetics, and antitumor activity of TRC105 in patients with advanced refractory solid tumors. Patients and Methods: Patients received escalating doses of intravenous TRC105 until disease progression or unacceptable toxicity using a standard 3 + 3 phase I design. Results: Fifty patients were treated with escalating doses of TRC105. The maximum tolerated dose (MTD) was exceeded at 15 mg/kg every week because of dose-limiting hypoproliferative anemia. TRC105 exposure increased with increasing dose, and continuous serum concentrations that saturate CD105 receptors were maintained at 10 mg/kg weekly (the MTD) and 15 mg/kg every 2 weeks. Common adverse events including anemia, telangiectasias, and infusion reactions reflected the mechanism of action of the drug. Antibodies to TRC105 were not detected in patients treated with TRC105 from Chinese hamster ovary cells being used in ongoing phase Ib and phase II studies. Stable disease or better was achieved in 21 of 45 evaluable patients (47%), including two ongoing responses at 48 and 18 months. Conclusion: TRC105 was tolerated at 10 mg/kg every week and 15 mg/kg every 2 weeks, with a safety profile that was distinct from that of VEGF inhibitors. Evidence of clinical activity was seen in a refractory patient population. Ongoing clinical trials are testing TRC105 in combination with chemotherapy and VEGF inhibitors and as a single agent in prostate, ovarian, bladder, breast, and hepatocellular cancer. Clin Cancer Res; 18(17); 4820–9. ©2012 AACR.

Phase 1 Study of Lumiliximab with Detailed Pharmacokinetic and Pharmacodynamic Measurements in Patients with Relapsed or Refractory Chronic Lymphocytic Leukemia

Purpose: Therapeutic antibodies have improved the outcome for patients with chronic lymphocytic leukemia (CLL). We conducted a phase 1, dose escalation and schedule optimization study of the primatized anti-CD23 antibody, lumiliximab, in patients with previously treated and refractory CLL. Experimental Design: Forty-six patients were assigned sequentially to cohorts 1 through 6 and received lumiliximab at 125, 250, or 375 mg/m2 weekly for 4 weeks; 500 mg/m2 weekly for 4 weeks [500(A)]; 500 mg/m2 thrice during week 1 then 500 mg/m2 weekly for the next 3 weeks [500(B)]; or 500 mg/m2 thrice a week for 4 weeks [500(C)], respectively. Results: The median age was 62 years (range, 47-80), and the median number of prior regimens was four (range, 1-13). No partial or complete responses were observed. Toxicity was limited and unrelated to dose. The pharmacokinetics of lumiliximab was similar to other IgG1 monoclonal antibodies with accumulation at doses ≥250 mg/m2 and a median terminal half-life of 7 days. Pharmacodynamic studies showed dose-dependent increases in soluble CD23, but no down-regulation of CD23 antigen. Saturation of CD23 receptors occurred at 250 mg/m2 and was maintained for ≥1 week following completion of therapy at ≥375 mg/m2. Conclusions: Treatment with lumiliximab seemed to be well tolerated and to have clinical activity in patients with relapsed or refractory CLL.

Phase 1/2 study of lumiliximab combined with fludarabine, cyclophosphamide, and rituximab in patients with relapsed or refractory chronic lymphocytic leukemia

Preclinical data demonstrate enhanced antitumor effect when lumiliximab, an anti-CD23 monoclonal antibody, is combined with fludarabine or rituximab. Clinical data from a phase 1 trial with lumiliximab demonstrated an acceptable toxicity profile in patients with relapsed or refractory chronic lymphocytic leukemia (CLL). We therefore pursued a phase 1/2 dose-escalation study of lumiliximab added to fludarabine, cyclophosphamide, and rituximab (FCR) in previously treated CLL patients. Thirty-one patients received either 375 mg/m(2) (n = 3) or 500 mg/m(2) (n = 28) of lumiliximab in combination with FCR for 6 cycles. The toxicity profile was similar to that previously reported for FCR in treatment of relapsed CLL. The overall response rate was 65%, with 52% of patients achieving a complete response (CR), which compares favorably with the CR rate previously reported for the FCR regimen alone in relapsed CLL. The estimated median progression-free survival for all responders was 28.7 months. The addition of lumiliximab to FCR therapy is feasible, achieves a high CR rate, and does not appear to enhance toxicity in previously treated patients with CLL. A randomized trial comparing lumiliximab plus FCR with FCR alone is underway to define the benefit of this combination in relapsed CLL. This trial was registered at clinicaltrials.gov as NCT00103558.

Twice-Weekly Paclitaxel and Weekly Carboplatin With Concurrent Thoracic Radiation Followed by Carboplatin/Paclitaxel Consolidation for Stage III Non–Small-Cell Lung Cancer: A California Cancer Consortium Phase II Trial

PURPOSE Recent studies have suggested the superiority of concurrent chemoradiotherapy and the efficacy of paclitaxel/carboplatin in advanced non-small-cell lung cancer (NSCLC). In view of those results, we sought to examine the safety and efficacy of administration of radiosensitizing paclitaxel twice weekly and carboplatin weekly with concurrent thoracic radiation therapy (XRT) followed by consolidation paclitaxel and carboplatin for stage III NSCLC in a multi-institutional phase II trial. PATIENTS AND METHODS Induction chemoradiotherapy consisted of paclitaxel 30 mg/m2 delivered intravenously (IV) for 1 hour twice weekly for 6 weeks, carboplatin at a dose based on an area under the concentration-time curve (AUC) of 1.5 mg/mL x min, given IV once weekly for 6 weeks, and concomitant XRT of 1.8 to 2.0 Gy daily for a total of 61 Gy. Patients who achieved a complete response, partial response, or stable disease received two 21-day cycles of consolidation chemotherapy consisting of paclitaxel 200 mg/m2 IV for 3 hours and carboplatin at a dose based on an AUC of 6 mg/mL x min. RESULTS Thirty-four patients were eligible. Their median age was 62 years (range, 39 to 73 years), 59% were female, 41% were male, 94% had a performance status of 0 or 1, 38% had stage IIIA NSCLC, and 62% had stage IIIB NSCLC. Common grade III and IV toxicities during the induction chemoradiation phase included esophagitis (38%) and neutropenia (12%). The most common adverse reaction during consolidation chemotherapy was grade III neutropenia in five patients (15%). The overall response rate was 71%, which was achieved in the induction phase. The median follow-up was 20 months, the median survival was 17 months, and 2-year actuarial survival rate was 40% (95% confidence interval, 20% to 65%). CONCLUSION This regimen is tolerable and results are promising. We recommend further evaluation of this regimen in a phase III trial.

Improved freedom from PSA failure with whole pelvic irradiation for high-risk prostate cancer

PURPOSE To determine the impact of whole pelvic irradiation on the risk of PSA failure in prostate cancer patients, at high predicted risk for lymph node involvement, receiving definitive radiotherapy. MATERIALS AND METHODS Between October 1987 and December 1995, 506 patients with clinically localized prostate cancer were treated with definitive radiotherapy at UCSF and affiliated institutions. Treatment consisted of 4-field whole pelvic irradiation followed by a prostate-only boost, or prostate-only treatment (median follow-up was 35 months and 30 months, respectively). PSA failure was defined as: 1. a PSA value > or = 1 ng/ml; or 2. a PSA value that rose > or = 0.5 ng/ml in < or = 1 year posttreatment on two consecutive measurements, with the first rise defined as the time of failure. The calculated risk of lymph node positivity (%rLN+) was defined as 2/3(iPSA) + 10(GS-6), and high risk was defined as %rLN+ > or = 15%. Univariate and multivariate analyses were performed. RESULTS A total of 201 high-risk patients were identified. High-risk patients who received whole pelvic irradiation had significantly improved freedom from PSA failure compared to those who received prostate-only treatment (median PFS = 34.3 months vs. 21.0 months; p = 0.0001). Potential confounding variables, including initial PSA, Gleason score, T stage, radiation dose, year of treatment, use of three-dimensional (3D) conformal techniques, and use of hormone therapy, did not account for the observed difference in time to PSA failure. Multivariate analysis revealed type of radiation treatment to be the most significant independent predictor of outcome. CONCLUSION Whole pelvic radiotherapy significantly improves the PSA failure-free survival in patients with a high calculated risk of lymph node positivity.

Positron Emission Tomography Imaging of CD105 Expression with a 64Cu-Labeled Monoclonal Antibody: NOTA Is Superior to DOTA

Optimizing the in vivo stability of positron emission tomography (PET) tracers is of critical importance to cancer diagnosis. In the case of 64Cu-labeled monoclonal antibodies (mAb), in vivo behavior and biodistribution is critically dependent on the performance of the bifunctional chelator used to conjugate the mAb to the radiolabel. This study compared the in vivo characteristics of 64Cu-labeled TRC105 (a chimeric mAb that binds to both human and murine CD105), through two commonly used chelators: 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Flow cytometry analysis confirmed that chelator conjugation of TRC105 did not affect its CD105 binding affinity or specificity. PET imaging and biodistribution studies in 4T1 murine breast tumor-bearing mice revealed that 64Cu-NOTA-TRC105 exhibited better stability than 64Cu-DOTA-TRC105 in vivo, which resulted in significantly lower liver uptake without compromising the tumor targeting efficiency. In conclusion, this study confirmed that NOTA is a superior chelator to DOTA for PET imaging with 64Cu-labeled TRC105.

Southwest Oncology Group phase II trial of concurrent carboplatin, etoposide, and radiation for poor-risk stage III non-small-cell lung cancer

PURPOSE A phase II study was conducted by the Southwest Oncology Group (SWOG) to assess the efficacy and toxicity of concurrent carboplatin, etoposide, and thoracic radiation (XRT) in a defined population of poor-risk patients with stage III non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS Patients with stage III NSCLC were eligible if they were excluded from cisplatin-based protocols because of poor pulmonary or renal function, history of congestive heart failure, hearing loss, peripheral neuropathy, or weight loss. Carboplatin 200 mg/m2 daily intravenously days 1, 3, 29, and 31 and etoposide 50 mg/m2 daily intravenously days 1 through 4 and 29 through 32 were administered. Beginning day 1, XRT was delivered at 1.8 to 2.0 Gy daily to a total dose of 61 Gy. RESULTS Within a period of 1 year, 63 patients were registered and 60 were eligible. Patient characteristics were age 47 to 79 years, performance status 0 to 1 (82%) and 2 (18%), and stages IIIA (60%) and IIIB (40%) NSCLC. The most common grades 3 and 4 toxicities included leukopenia (50%), thrombocytopenia (23%), and esophagitis (15%). There were no treatment-related deaths. The overall confirmed response rate was 29%, and median overall survival was 13 months (95% confidence interval, 11 to 14 months). The 2-year survival rate was 21%. CONCLUSION This chemoradiotherapy regimen is well tolerated in poor-risk patients and yields a median survival similar to that of good-risk patients who received cisplatin-based chemoradiotherapy. This chemoradiotherapy regimen will be compared with XRT alone in poor-risk patients with stage III NSCLC in a randomized phase III trial.

Multimodality imaging of breast cancer experimental lung metastasis with bioluminescence and a monoclonal antibody dual-labeled with 89Zr and IRDye 800CW

Metastatic breast cancer is incurable. The goal of this study was to develop a positron emission tomography (PET)/near-infrared fluorescent (NIRF) probe for imaging CD105 expression in breast cancer experimental lung metastasis. TRC105, a chimeric anti-CD105 antibody, was dual-labeled with a NIRF dye (IRDye 800CW) and (89)Zr to yield (89)Zr-Df-TRC105-800CW. Luciferase-transfected 4T1 murine breast cancer cells were injected intravenously into female mice to establish the tumor model. Bioluminescence imaging (BLI) was carried out to noninvasively monitor the lung tumor burden. PET imaging revealed that 4T1 lung tumor uptake of (89)Zr-Df-TRC105-800CW was 8.7 ± 1.4, 10.9 ± 0.5, and 9.7 ± 1.1% ID/g at 4, 24, and 48 h postinjection (n = 4), with excellent tumor contrast. Biodistribution studies, blocking, control studies with (89)Zr-Df-cetuximab-800CW, ex vivo BLI/PET/NIRF imaging, and histology all confirmed CD105 specificity of the tracer. Broad clinical potential of TRC105-based agents was shown in many tumor types, which also enabled early detection of small metastasis and intraoperative guidance for tumor removal.

Radiation dosimetry results from a phase II trial of Ibritumomab Tiuxetan (Zevalin™) radioimmunotherapy for patients with non-Hodgkin's lymphoma and mild thrombocytopenia

This was a 30-patient Phase II trial of reduced-dose (90)Y ibritumomab tiuxetan (Zevalin) RIT for patients with low-grade, follicular, or transformed B-cell NHL and mild thrombocytopenia. Patients were given an imaging dose of (111)In-labeled ibritumomab tiuxetan for dosimetry measurements. One week later, patients were administered a therapeutic dose of 0.3 mCi/kg (11 MBq/kg) (90)Y ibritumomab tiuxetan. Both (111)In- and (90)Y-labeled ibritumomab tiuxetan doses were preceded by an infusion of 250 mg/m(2) rituximab (Rituxan, MabThera) an unlabeled chimeric anti-CD20 antibody, to clear peripheral blood B cells and improve biodistribution of the radiolabeled antibody. For all 30 patients, normal organ and red marrow radiation absorbed doses were well below protocol-defined limits of 2000 cGy and 300 cGy, respectively. Median radiation absorbed doses were 48 cGy to red marrow (range: 6.5-95 cGy), 393 cGy to liver (range: 92-1581 cGy), 522 cGy to spleen (range: 165-1711 cGy), 162 cGy to lungs (41-295 cGy), and 14 cGy to kidneys (0.03-65 cGy). Though most correlative analyses were negative, certain analyses demonstrated a statistically significant correlation between the severity or duration of thrombocytopenia and pharmacokinetic or dosimetric parameters. These correlations were not consistent across the total patient population, and therefore, could not be exploited to predict hematologic toxicity.