Immune Checkpoint Inhibition and Single Fraction Stereotactic Radiosurgery in Non-Small Cell Lung Cancer Brain Metastases: An International Multicenter Study of 395 Patients

PURPOSE/OBJECTIVE(S)

Brain metastases most commonly arise from non-small cell lung cancer (NSCLC). In recent years, immune checkpoint inhibitors (ICI) have demonstrated improvements in overall survival (OS) in NSCLC. However, concerns remain about the risk of radiation necrosis (RN) when ICI are administered with stereotactic radiosurgery (SRS).

MATERIALS/METHODS

Logistic regression was used to evaluate prognostic factors associated with the development of any grade RN and symptomatic RN. Cumulative incidence of RN was evaluated using competing risks analysis and the Fine and Gray model, where the null hypothesis was rejected for p < 0.05.

RESULTS

There were 395 patients with 2,513 brain metastases treated across 11 international institutions included in the analysis. The median follow-up was 14.2 months. Median patient age was 67 years (Interquartile Range [IQR]: 61-73), 53.4% were male, the median Karnofsky Performance Status was 80 (IQR: 80-90), and 88.6% has active extracranial disease at the time of SRS. The median margin dose was 19 Gy (IQR: 18-20), 97.5% of patients were treated on the Gamma Knife ®, 3.8% underwent prior whole brain radiation therapy (WBRT). The median V12 Gy was 5.2 cm3 and 36.5% of patients had a V12 Gy ≥ 10 cm3, anti-PD-1 agents were administered in 91.6% of patients. A V12 Gy ³ 10 cm3 was associated with an increased risk of developing any grade RN; odds ratio (OR): 2.12, p = 0.04 and OR: 2.18; p = 0.03 on univariable and multivariable analysis, respectively. Similarly, a V12 Gy ≥ 10 cm3 was associated with an increased risk of developing symptomatic RN; OR: 3.80, p = 0.003 and OR: 3.95; p = 0.003 on univariable and multivariable analysis, respectively. Receipt of concurrent ICI and prior WBRT were not statistically significant. At 1-year, the cumulative incidence of any grade and symptomatic RN was 4.8% and 3.8%, respectively. The cumulative incidence of any grade RN was 3.8% vs. 5.3% for the concurrent and non-concurrent groups at 1-year, respectively (p = 0.35). The cumulative incidence of symptomatic RN was 3.8% vs. 3.6% for the concurrent and non-concurrent groups at 1-year, respectively (p = 0.95).

CONCLUSION

The risk of any grade and symptomatic RN following SRS and ICI administration for NSCLC brain metastases increases as the V12 Gy exceeds 10 cm3. Concurrent ICI and SRS does not appear to increase this risk. Radiosurgical planning techniques should aim to minimize the V12 Gy.

Abstract 4746: Mapping genes for invasive urinary bladder cancer in the dog

Transitional Cell Carcinoma (TCC) is the most common cancer of the urinary bladder in pet dogs. In approximately 50% of dogs diagnosed with TCC the disease will spread to other organs in the body such as the lungs or liver. Drugs used to treat TCC are only partially effective and as a result most affected dogs ultimately die from the cancer. While it can be found in most breeds, there are a small number for which the risk is greatly increased five to twenty-fold, indicating an inherited component to the disease.

In order to identify genetic mutations that increase susceptibility to TCC of the bladder, we have conducted a genome-wide association study (GWAS) using more than 100 Scottish terriers (ST), West Highland White terriers (WHWT), and Shetland Sheepdogs (SSD) with biopsy confirmed TCC. Controls included over 100 dogs of the same three breeds that were nine years or older, and that had not been diagnosed with any form of cancer. All germline DNA samples were run on the Affymetrix v2 canine SNP chip. Data were analyzed to test for an association between markers and disease. Following correction for population structure and relatedness among individuals of the same breed we identified one primary susceptibility locus (locus1) within the Scottish terrier population (p = 5 × 10-13) and a second locus (locus2) in West Highland White terriers and Shetland Sheepdogs (p = 3 × 10-7). The association at locus1 is increased with the addition of WHWT but not SSD. Fine mapping of locus1 with a dense set of 250 SNPs spanning a 4.5 Mb region revealed a strong association across a group of genes involved in multiple cancer pathways, including some commonly deleted in human bladder cancer tumors. Haplotype analysis across this region identified two primary haplotype blocks with significant associations. Locus2 was associated with the TCC in the WHWT and SSD, when ST were excluded. Preliminary data suggests evidence of a reduced heterozygosity in both cases and controls at locus2 in the ST and we hypothesize that STs are nearing fixation at locus2, thus explaining the twenty-fold increased risk associated with this breed. We are currently further fine mapping both regions by resequencing and genotyping additional 750 SNPs and probes to assess copy number variation using a custom Goldengate assay.

The identification of causal mutations will lead to a better understanding of the genetic causes of bladder cancer. In addition, since TCC of the bladder in dogs shares a similar histopathologic appearance and biological behavior with human invasive TCC of the bladder, identification of genetic risk factors for TCC will allow selection of molecular targets for early detection and treatment in both humans and dogs.

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 4746.

Abstract A48: In vivo evaluation of Cox-2 inhibition to prevent the progression of invasive urinary bladder cancer

Background: Invasive transitional cell carcinoma (InvTCC) of the urinary bladder has a propensity to metastasize, is only partially responsive to chemotherapy, and causes &gt; 14,000 deaths yearly in the United States. The development of effective means to prevent the development and progression of InvTCC is crucial. Cyclooxygenase-2 (Cox-2) is over-expressed in InvTCC in humans and animals. In a pilot study, a Cox-2 inhibitor induced apoptosis of InvTCC in humans. Cox-2 inhibitors may offer an avenue for prevention of InvTCC progression. The purpose of this study was to determine the effects of Cox-2 inhibitor treatment in preventing the progression of InvTCC in a highly relevant animal model, canine InvTCC. Naturally-occurring InvTCC in dogs closely mimics human InvTCC in cellular and molecular features (including Cox-2 expression), sites and frequency of metastasis, and response to therapy.

Methods: Dogs with histologically confirmed InvTCC who failed or whose owner declined standard chemotherapy protocols, and with expected survival of &gt; 6 weeks were prospectively enrolled. The Cox-2 inhibitor deracoxib (Novartis, Greensboro, NC) was given as a single agent with a planned dose of 3mg/kg/day orally. Dogs were evaluated prior to and during therapy with abdominal ultrasound including mapping of the urinary bladder masses, thoracic radiographs, complete blood count, serum biochemistry profiles and urinalyses. Toxicity was assessed by clinical signs and serial blood work. Tumor response was defined as: complete remission (CR), no evidence of disease detected; partial remission (PR) ≥ 50% reduction in tumor volume; stable disease (SD) &lt;50% change in tumor volume; or progressive disease (PD) ≥ 50% increase in tumor volume or new lesions. A whole blood assay was used to confirm selective Cox-2 inhibition.

Results: Thirty-nine dogs with InvTCC received deracoxib at a mean dose of 2.79 mg/kg/day (range 1.18 mg/kg/day to 4.08mg/kg/day). Of 39 dogs, 1 had nodal metastasis, and 3 had distant metastasis at diagnosis. Initial responses in 30 dogs with measurable disease included PR in 4 dogs (13%), SD in 17 dogs (57%), and PD in 3 dogs (10%); and in 6 dogs, response to therapy has not been determined. Mean time to subsequent PD (n=20) was 167 days (range 36 – 482 days). After PD was noted, 10 dogs went on to receive other therapy (leukeran, mitoxantrone, mitomycin-C, 5 azacitidine, carboplatin). Of the 39 dogs treated, 9 had microscopic residual disease after surgical intervention. Of these 9 dogs, 4 had relapse (median time to relapse, 221 days), and 3 had not relapsed at the time of death from other causes (median time to death 772 days). The median survival times for dogs with measurable disease and microscopic disease were 349 and 772 days, respectively.

Conclusion: The results of this work help justify further study of the use of Cox-2 inhibitors in preventing the progression of InvTCC.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):A48.

Prognosis following surgical excision of canine cutaneous mast cell tumors with histopathologically tumor-free versus nontumor-free margins: a retrospective study of 31 cases

The purpose of this study was to determine if the presence of histopathologically tumor-free versus nontumor-free margins was prognostic for relapse or tumor-related death in dogs following surgical excision of single or multiple cutaneous mast cell tumors confined to the skin without evidence of metastasis to lymph nodes or other noncutaneous sites. Differences in tumor-related death or frequency of relapse between the two groups were not significant. Failure to achieve histopathological tumor-free margins frequently did not lead to local relapse. All tumor-related deaths occurred following local relapse. The lack of statistical support for an association between prognosis and histopathological tumor-free versus nontumor-free margins may be a result of small sample size.

Canine anal sac adenocarcinomas: clinical presentation and response to therapy

A retrospective study of 43 dogs with anal sac adenocarcinoma (ASAC) was performed to characterize the clinical presentation and response to treatment. Clinical signs at presentation varied considerably, with signs related either to sublumbar nodal metastasis (tenesmus or constipation) or hypercalcemia (polyuria-polydipsia and anorexia) being the most frequent findings. At the time of presentation, 23 (53%) dogs had hypercalcemia and 34 (79%) had metastases, with the regional lymph nodes (31 dogs, 72%) being the most common site of metastasis. A variety of chemotherapeutic agents were administered, with partial remission (PR) recorded in 4 of 13 (31%) dogs treated with cisplatin and in 1 of 3 (33%) dogs treated with carboplatin. The median survival for all dogs was 6 months (range, 2 days-41 months). There was no statistical association between the presence of hypercalcemia and survival, although the power of the study to detect an increase in survival of 3 months was low (.33). We conclude that platinum chemotherapy has antitumor activity in canine apocrine gland carcinoma and that further study of these agents is warranted.

Cisplatin chemotherapy for treatment of thyroid carcinoma in dogs: 13 cases

The medical records of 13 dogs (10 spayed females, one intact male, one castrated male, and one dog of unknown gender) with histopathologically diagnosed thyroid carcinoma that were treated with cisplatin chemotherapy were reviewed. The mean age was 10.6 years. Three of the dogs were beagles. One dog had a c-cell medullary carcinoma, while the remaining 12 had follicular thyroid carcinoma. Eight of 13 dogs had tumors greater than 5 cm in diameter. In all 11 tumors for which information was available in the medical record, the masses were attached to underlying tissue. One dog underwent a complete remission, six had partial remissions, three had stable disease, and three had progressive disease. The mean time between initiation of cisplatin chemotherapy and development of progressive disease was 223.7 days (median, 202 days), with a mean survival time of 191.8 days (median, 98 days).

Antibodies to canine granulocyte colony-stimulating factor induce persistent neutropenia

A severe persistent neutropenia developed in a rabbit that was injected intradermally with 120, 60, 60, and 120 micrograms of recombinant canine granulocyte colony-stimulating factor (cG-CSF) on days 1, 22, 31, and 44, respectively. The neutropenia was present from day 44 to day 205. The nadir of the neutropenia (60 cells/microliters) occurred in conjunction with peak antibody titer (640,000) to cG-CSF on day 58. The immune antiserum from this rabbit reacted positively for cG-CSF on Western blot analysis. The immune antiserum also neutralized the activity of cG-CSF. On day 160, examination of the bone marrow showed marked granulocytic hypoplasia and mild erythroid hyperplasia. On day 205, the rabbit was still neutropenic (430 cells/microliters), even though the last injection of cG-CSF was given 161 previously. Necropsy on day 205 showed that there was still mild granulocytic hypoplasia with mild erythroid hyperplasia. Because of the lack of any inflammatory foci found at necropsy and the granulocytic hypoplasia, it was thought that the neutropenia was most likely due to decreased production and was not a consumptive process. It is hypothesized that the antibody that was produced to cG-CSF neutralized the effect of endogenous rabbit granulocyte colony-stimulating factor and prevented the normal proliferation and maturation of the rabbit neutrophils.