Activity of fractionated radioimmunotherapy with clivatuzumab tetraxetan combined with low-dose gemcitabine (Gem) in advanced pancreatic cancer (APC)

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Background: The90Y-labeled anti-mucin humanized mAb, clivatuzumab tetraxetan (90Y-hPAM4), is in clinical development in APC. A phase I/II trial of 90Y-hPAM4 with low-dose radiosensitizing Gem has now concluded 90Y-dose escalation.

Methods: Pts with untreated, inoperable, stage 3-4 APC received 200 mg/m2 Gem once-weekly x 4 with 90Y-hPAM4 on wks 2-4, and with 90Y escalated in cohorts by 3+3 design. Tumor responses were assessed by CT, FDG/PET and serum CA19.9, with cycles repeated until progression or unacceptable toxicity.

Results: Of 42 pts (40-87 yrs, ECOG PS 0-1, 36 stage 4), 4 withdrew early while 38 received weekly x 3 90Y doses of 6.5 (N=4), 9 (N=12), 12 (N=17) and 15 (N=5) mCi/m2. Treatment was well-tolerated with few non-hematologic side-effects, including 13 pts retreated with 1-3 additional cycles. CTCv3 grade 3-4 plts or ANC developed in 21/38 (55%) pts after cycle 1 and all (100%) retreated pts after last cycle. Escalation reached limits on radiation doses to the marrow, but hematologic suppression was reversible without major infections or bleeding events, except for 3 pts after repeated cycles, one with extensive marrow tumor infiltration. By CT, the overall disease control rate was 55%, including 6 pts (16%) with partial responses (PRs) by RECIST criteria and 15 pts (39%) with stabilization as best response. After cycle 1, 43% (10/23) improved by PET studies (negative or >25% reduced uptake), and 36% (9/25) with elevated CA19.9 levels had >50 decreases. With 26% (10/38) of pts still in follow-up, 55% (21/38) have now achieved survival of ≥ 6 months [18% (7/38) ≥ 1 yr]. Treatment outcome may increase with 90Y dose, since pts treated at 3 x ≥12 mCi/m2 vs ≤9 mCi/m2 had 19% vs 6% PRs by CT, 47% vs 22% CA19.9 decreases, 63% vs 25% PET improvement, and 64% vs. 44% survival ≥ 6 months. Anecdotally, PS and pain level improved, which needs validation. Updated survival will be presented at the meeting.

Conclusions: Fractionated 90Y-hPAM4 plus low-dose Gem showed encouraging therapeutic activity with manageable hematological toxicity. The 12-mCi/m2 dose level was selected for continued dose exploration now underway, involving standard Gem doses and adding maintenance Gem.

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First clinical experience with 90Y-radiolabeled humanized anti-MUC1 antibody (hPAM4) in patients with advanced pancreatic cancer: A phase I study

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Background: The humanized antibody, hPAM4, specifically targets an epitope in the mucin glycoprotein MUC1 expressed in most pancreatic cancers, but not normal pancreas or most other normal tissues. This study evaluated the dose-limiting toxicity (DLT), maximum tolerated dose (MTD), pharmacokinetics (PK), dosimetry and preliminary efficacy of 90Y-DOTA-hPAM4 administered as a single dose to patients (pts) with pancreatic adenocarcinoma. Methods: Pts with locally advanced disease and progression on 1 prior therapy (TX) or metastatic disease with 0–1 prior TX’s were eligible if they were ≥ 4 wks beyond prior TX, had adequate hematology/chemistries, with measurable disease, but no lesion >10 cm. Pts initially received 111In-hPAM4 followed by 7 days of serum samples and imaging for PK, biodistribution and organ radiation dose analysis. Pts then received a single infusion of 90Y-hPAM4 with the 90Y dose escalated in cohorts of 3–6 pts (5-mCi/m2 increments) until 2 evaluable pts/cohort encountered DLT. Treatment toxicity was evaluated by NCI CTC v. 3 criteria and tumor response by CT-based RECIST criteria. Results: Fifteen pts (8F/7M; median age 60; 11 metastatic/4 locally advanced;13 with, 2 without prior TX) received 90Y-hPAM4 at a dose level of 15 mCi/m2 (n=4), 20 mCi/m2 (n=7), and 25 mCi/m2 (n=4). Pre-therapy 111In-hPAM imaging showed acceptable biodistribution and organ radiation dosimetry in all pts. Four wks after treatment, 1 pt at 15 mCi/m2 and 2 pts at 20 mCi/m2 had CT responses, with 32–51% shrinkage of their pancreatic mass, while 3 other pts at various dose levels had stable target lesions by CT. All pts showed disease progression at or after wk 8. The only significant drug-related toxicity was hematologic, with >1 DLT (>7 day grade 4 thrombocytopenia and/or neutropenia) encountered at the 25 mCi/m2 level. Conclusions: For 90Y-hPAM administered once as a single agent, hematologic toxicity was dose-limiting, the MTD was established at 20 mCi/m2, and CT demonstrated several transient reductions or stabilization of index lesions. Based on this Phase I experience, combined/sequential treatment with chemotherapy and fractionated radioimmunotherapy is being considered for future trials.

No significant financial relationships to disclose.

Yttrium-90 microsphere selective internal radiation treatment (SIRT) with concomitant chemotherapy (Chemo-SIRT) as first/second-line therapy in patients with colorectal cancer liver metastases

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Background: Yttrium-90 (Y-90) microsphere selective internal radiation treatment (SIRT) has been studied in patients (pts) with colorectal cancer liver metastases (CRCLM) in combination with FUDR and 5FU-LV with promising results. This is a phase II trial of SIRT and concurrent contemporary chemotherapy in the frontline management of CRCLM. Methods: Pts with metastatic disease limited predominantly to the liver were eligible for the study. Other entry criteria included KPS 70 or >, 3 month life expectancy and adequate marrow and renal reserve. Pre-treatment evaluations included the assessment of liver function, CEA level, 18F-FDG-PET/CT imaging, an angiogram and a 99mTc-MAA (macroagregate albumin) scan. SIRT with Y-90 resin microspheres (Sirtex Medical, Lake Forest, IL) was administered on day 2 of the first chemotherapy (Fol-Fox or Fol-Firi) course in either lobar or whole-liver fashion. Chemotherapy was repeated on a biweekly schedule. CEA levels and 18F-FDG-PET/CT based anatomic and functional volume (Vf) changes were used to determine tumor response at 4, 8, and 12 weeks after therapy. CTC v3 toxicity grades were used to classify adverse events. Results: 6 pts were treated as first-line and 2 pts as second-line. 5 pts received single lobe and 3 pts received whole liver treatment. Administered activity of Y-90 microspheres ranged from 0.9 to 3.1 GBq (mean 2.3 GBq). Mean tumor radiation absorbed dose was 203.6 Gy (Range 91.0–351.4 Gy). Mean liver absorbed dose was 47.8 Gy (Range 7.9–85.9 Gy). 6/8 pts had complete/near-complete metabolic response with a mean tumor Vf decrease in target lobe(s) of 98%). The remaining 2 pts demonstrated > 50% reduction in Vf in target lobe(s). A parallel decrease in CEA level was observed in responding pts. Surgical downstaging was attained in 3/8 pts. 2 pts developed grade III toxicity (one gastric ulcer and one alkaline phosphatase elevation). Conclusion: Chemo-SIRT as first-line therapy has a high level of response in CRCLM as measured by reductions in functional tumor volume and CEA level. Further follow-up of these pts is needed to confirm that this response is of clinical significance in terms of improved surgical downstaging and survival.

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Antiangiogenic therapy with somatostatin receptor-mediated in situ radiation

Tumor growth and the development of metastases require an angiogenic response. Angiogenic vessels uniquely express somatostatin subtype 2 (sst 2) receptors that can transport somatostatin or its analogs into the cell. We hypothesized that radiolabeled somatostatin analogs could inhibit the angiogenic response by selectively destroying proliferating endothelial cells. We evaluated the antiangiogenic effects of 111In-pentetreotide, an sst 2-preferring somatostatin analog in a human vessel model. Disks of human placental vein were embedded in fibrin gels in culture and observed for angiogenic sprouting for 14 days. Vein disks were treated with 111In-pentetreotide (1.5, 15, and 150 microCi/mL) on the day of implantation. Control groups included disks treated with nutrient medium alone, with 111In-chloride, and with unlabeled pentetreotide. The percentage of wells that initiated an angiogenic response and the overall length and density of neovessel sprouts were assessed on Day 14. 111In-pentetreotide treatment did not completely block initiation of the angiogenic response but significantly decreased the growth of neovessels after initiation. Both the receptor-specific Auger electron-induced and nonspecific gamma radiation-mediated effects contributed to the angiotoxicity.

Post-surgical ablation of thyroid remnants with high-dose (131)I in patients with differentiated thyroid carcinoma

The aims of this study were to evaluate the efficacy of an empirically determined "fixed" high ablative dose of radioiodine ((131)I) therapy and to determine the utility of ultrasonography (US) in dose determination. A retrospective analysis was performed of 242 thyroid cancer cases treated with "fixed" high-dose (131)I for ablation of thyroid remnants without a pre-ablative (131)I diagnostic scintigraphy or radioiodine uptake study. Treatment doses ranged from 1850 MBq (50 mCi) to 7.4 GBq (200 mCi). The selection of the treatment dose was based on the surgical and pathological findings as well as the remnant thyroid volume calculated by US. A successful ablation was defined as the absence of activity in the thyroid bed on subsequent imaging studies. Successful ablation was obtained in 218 of the 242 patients (90%). In 162 of the 218 patients (74.3%), successful ablation was achieved after a single (131)I treatment. The remnant thyroid volume calculated by US was significantly different (P=0.04) between those who were successfully ablated and those who were not. The total (131)I dose needed for successful ablation was significantly higher in males (P=0.003). Patients with higher post-operative thyroglobulin (Tgb) levels and patients with a higher stage of disease required higher doses (P=0.036 and P=0.021 respectively). Serum Tgb levels were under 10 ng.ml(-1) in 220 of the 242 patients (90%) following radioiodine ablation while not receiving L-thyroxine suppression. Nineteen patients (7.8%) showed metastases on post-therapy scan and successful treatment was achieved in 11 of 19 (57.8%). Four of the 19 patients with distant metastases (revealed on post-treatment scan) were found to have been given a treatment dose of less than 200 mCi based on the proposed empirical approach. These results indicate that "fixed" high-dose (131)I treatment is clinically feasible with an acceptable dose underestimation rate, and the utilization of US in the determination of the thyroid remnant volume provides more accurate and reproducible results.

Clinical utility of frozen section in sentinel node biopsy in breast cancer

One hundred sixty-five breast cancer patients underwent a sentinel lymph node biopsy procedure over a period of 2 years. Sentinel node (SN) could be successfully localized in 157 (95%) of the patients. Complete axillary lymph node dissection was performed only if the frozen section (FS) revealed a positive SN. All SN specimens were further evaluated by hematoxylin and eosin on multiple sections and cytokeratin immunohistochemisty. The patients whose SNs were negative by FS but positive by permanent histopathologic evaluation underwent a delayed axillary lymph node dissection. SN was positive in 41 of 157 (26%) patients. Eighteen (44%) of the 41 patients with SN metastases were diagnosed intraoperatively by FS and underwent a one-stage definitive surgical treatment. The benefit of FS was most notable in patients with T1c and larger lesions.

Antitumor and antiangiogenic effects of somatostatin receptor-targeted in situ radiation with (111)In-DTPA-JIC 2DL

INTRODUCTION

Expression of somatostatin receptor subtype 2 (sst 2) in angiogenic tumor vessels appears to be homogeneous, while tumor cell expression of this receptor is often heterogeneous. We have developed a novel in vitro three-dimensional tumor angiogenesis model to study the antitumor and the antiangiogenic effects of radiolabeled somatostatin analogs. We hypothesized that targeted in situ radiation with an Auger electron-emitting radiolabeled somatostatin analog would produce receptor-specific cytotoxicity in sst 2-expressing cells.

MATERIALS AND METHODS

IMR-32 human neuroblastoma (sst 2-positive) and MDA MB-231 human breast cancer (sst 2-negative) xenografts were created in nude mice from monolayer cell cultures. Fragments of these tumors were embedded in three-dimensional fibrin gels supplemented with endothelial growth media and incubated for a period of 14 days. Tumor fragments were treated with 50 microCi/ml of (111)In-JIC 2DL, a sst 2-preferring somatostatin analog, or medium on Day 1. Initial angiogenic activity was determined at 48 h and the mean angiogenic score and tumoricidal responses were assessed on Day 14.

RESULTS AND CONCLUSION

Tumoricidal effects of (111)In-JIC 2DL were seen only in sst 2-positive IMR-32 tumors. However, the angiogenic response was inhibited in both IMR-32 and MDA MB-231 tumors independent of the tumor cells' sst 2 status. Somatostatin receptor-mediated in situ radiation therapy has profound cytotoxic effects on angiogenic blood vessels and sst 2-expressing tumor cells.

A thousand points of light or just dim bulbs? Radiolabeled antibodies and colorectal cancer imaging

Radioimmunoscintigraphy (RIS) is coming into its own as an imaging modality in clinical oncology. Early experience with indium-111-labeled intact murine monoclonal antibodies (MoAbs) in colorectal cancer suggested that RIS images hepatic metastases poorly. Moreover, an antimurine immune response was frequently provoked, precluding multiple follow-up RIS studies in individual patients due to reticuloendothelial sequestration of the radioimmunoconjugate before tumor targeting could occur. Recent trials of technetium-99m-labeled antibody fragments and human MoAbs have demonstrated significant improvement in imaging efficacy, and repeated or serial imaging is possible because of the absence of associated immunogenicity. RIS is demonstrably more sensitive than conventional diagnostic modalities (CDM) such as computed tomography (CT) for detection of extrahepatic abdominal and pelvic colorectal carcinoma and is complementary to CDM in imaging liver metastases. In a surgical decision-making analysis comparing CT, RIS (IMMU-4 99mTc-Fab'; CEA-Scan), and CT plus RIS in patients with recurrent or metastatic colorectal cancer, CT plus RIS improved correct prediction of resectability by 40% and correct prediction of unresectability by 100% compared with CT alone. At the present time, RIS used in combination with CDM contributes an incremental improvement in diagnostic accuracy in colorectal cancer patients with known or suspected recurrent disease. Basic and clinical research currently in progress promises to yield agents and methods that provide rapid high-resolution imaging, high tumor-to-background ratios in all organs at risk for tumor recurrence or metastasis, negligible immunogenicity and toxicity, and a significant further improvement in the accuracy of clinical decision making in oncology patients.

Unfiltered sulfur colloid and sentinel node biopsy for breast cancer: technical and kinetic considerations

BACKGROUND

There are few clinical data on technical limitations and radiocolloid kinetics related to sentinel lymph node (SLN) biopsy for breast cancer.

METHODS

In 70 clinical node-negative patients, unfiltered 99mTc sulfur-colloid was injected peritumorally and cutaneous hot spots were mapped with a gamma probe. SLN biopsy was performed followed by axillary lymph node dissection. Missed radioactive nodes (nodes not under hot spots) were removed from axillary lymph node dissection specimens and submitted separately.

RESULTS

At least one hot spot was mapped in 69 patients (98%) and SLNs were retrieved in 62 (89%). No radiolabeled nodes were found in five (7%) and only nodes not under hot spots were retrieved in three patients (4%). Residual nodes not under hot spots were retrieved in 17 patients (24%) in whom at least one SLN specimen had been found. Diffuse radioactivity around the radiocolloid injection site impeded identification of all radiolabeled nodes during SLN biopsy, and was responsible for one of two false negatives (20 node-positive patients; false-negative rate 10%). Hot spot radioactivity, number of radiolabeled nodes, and nodal radioactivity did not change with time interval from radiocolloid injection to surgery (0.75-6.25 hours).

CONCLUSIONS

Although SLN localization rate is high, intraparenchymal injection may predispose to failure of radiocolloid migration, failure to identify SLNs because of high radiation background, and false-negative outcomes. Alternative routes of radiocolloid administration should be explored.

Sentinel lymph node localization in early breast cancer

METHODS

Thirty-two patients with clinical node-negative breast cancer underwent sentinel node localization study as part of a National Cancer Institute-sponsored multicenter trial. Anatomical and histopathologic characteristics of sentinel lymph node (SLN) and a kinetic analysis of nodal uptake were studied. Patients were injected with 1 mCi/4 ml unfiltered 99mTc-sulfur colloid in four divided doses around the palpable lesion or immediately adjacent to the excision cavity if prior biopsy was performed. SLN biopsy was performed 1.5-6 hr (mean = 3 hr) postinjection. Intraoperative localization was performed using a gamma probe. All patients underwent complete axillary dissection.

RESULTS

SLN was identified in 30 of 32 (94%) patients. There were no false-negative SLN biopsies.

CONCLUSION

This study supports the clinical validity of SLN biopsy in breast cancer and confirms that, unlike the blue dye technique, the learning curve with unfiltered 99mTc-sulfur colloid and the gamma detection probe is short, and SLN localization is achievable in over 90% of cases by surgeons with modest experience. The use of unfiltered 99mTc-sulfur colloid (larger particle size) with larger injected volume permits effective localization of SLNs.

Somatostatin receptor expression in Hürthle cell cancer of the thyroid

Somatostatin receptor expression, which was not a previously described marker for Hürthle cell cancer of the thyroid, was demonstrated by in vivo imaging with (111)In-pentetreotide in three patients. This phenomenon not only adds another imaging technique to the nuclear medicine armamentarium for detecting recurrent and metastatic cancer in patients with Hürthle cell cancer but also opens up an alternative therapeutic avenue with somatostatin analogs or their radiolabeled compounds.

Gamma probe guided sentinel node biopsy in breast cancer

Axillary lymph node status is the most important pathological determinant of prognosis in early breast cancer. Determination of axillary status is crucial in clinical decision-making. It is currently accepted that the total axillary lymphadenectomy is the most reliable staging procedure. However, routine axillary dissection does not benefit a majority of early breast cancer patients who are node-negative, and the patients sustain the potential morbidity and the economic cost of this procedure. There is substantial evidence that there is an orderly progression of breast cancer metastases in a lymphatic basin, sentinel node being the first node to receive lymphatic drainage from the tumor site. Sentinel lymph node biopsy may prove to be the optimal sampling technique for staging of breast cancer patients. A large multicenter trial to study the clinical validity of sentinel lymph node biopsy in breast cancer is underway. This paper addresses the rationale for sentinel lymph node biopsy and discusses the technical issues with regard to anatomy and physiology of breast lymphatics.

Radioimmunoscintigraphy of colorectal carcinoma using technetium-99m-labeled, totally human monoclonal antibody 88BV59H21-2

Radioimmunoscintigraphy (RIS) using human monoclonal antibodies offers the important clinical advantage of repeated imaging over murine monoclonal antibodies by eliminating the cross-species antibody response. This article reports a Phase I-II clinical trial with Tc-99m-labeled, totally human monoclonal antibody 88BV59H21-2 in patients with colorectal carcinoma. The study population consisted of 34 patients with colorectal cancer (20 men and 14 women; age range, 44-81 years). Patients were administered 5-10 mg antibody labeled with 21-41 mCi Tc-99m by the i.v. route and imaged at 3-10 and 16-24 h after infusion using planar and single-photon emission computed tomographic (CT) techniques. Pathological confirmation was obtained in 25 patients who underwent surgery. Human antihuman antibody (HAHA) titers were checked prior to and 1 and 3 months after the infusion. RIS with Tc-99m-labeled 88BV59H21-2 revealed a better detection rate in the abdomen-pelvis region compared with axial CT. The combined use of both modalities increased the sensitivity in both the liver and abdomen-pelvis regions. Ten patients developed mild adverse reactions (chills and fever). No HAHA response was detected in this series. Tc-99m-labeled human monoclonal antibody 88BV59H21-2 RIS shows promise as a useful diagnostic modality in patients with colorectal cancer. RIS alone or in combination with CT is more sensitive than CT in detecting tumor within the abdomen and pelvis. Repeated RIS studies may be possible, due to the lack of a HAHA response.