Clinical Outcomes of Breast Proton Radiation Therapy: A Multi-institutional Analysis of the Proton Collaborative Group Registry

Clinical Outcomes of Breast Proton Radiation Therapy: A Multi-institutional Analysis of the Proton Collaborative Group Registry

Volume 99  Number 2S  Supplement 2017 1098 Targeting Centrosomal Clustering in Combination With Radiation as a Novel Treatment for Lung Cancer N. R...

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Volume 99  Number 2S  Supplement 2017

1098 Targeting Centrosomal Clustering in Combination With Radiation as a Novel Treatment for Lung Cancer N. Raman,1 G. Lemtiri-Chlieh,1 K. Nugent,1 M. Ballew,1 T. Peck,1 M. Levine,1 R. Malek,1 H. Wang,1 A. Annadanam,1 K. Taparra,1 A. Holland,2,3 and P.T. Tran1; 1Johns Hopkins University School of Medicine, Department of Radiation Oncology and Molecular Radiation Sciences, Baltimore, MD, 2Johns Hopkins University School of Medicine, Department of Oncology, Baltimore, MD, 3Johns Hopkins University School of Medicine, Department of Molecular Biology and Genetics, Baltimore, MD Purpose/Objective(s): Lung cancer is the most common cause of cancer mortality in the US with an overall survival rate of 15%. In contrast to most normal cells, the majority of lung cancer cells have extra copies of centrosomes or supernumerary centrosomes (SC) and form multipolar mitotic spindles, which, if not corrected, lead to lethal multipolar divisions. To overcome this, lung cancer cells cluster their centrosomes into two spindle poles, enabling tumor cells to survive. Inhibition of centrosome clustering results in the selective killing of cancer cells with SC by forcing them into lethal multipolar divisions while sparing healthy tissues with normal centrosome numbers. We hypothesize that the inhibition of centrosomal clustering will result in the preferential radiosensitization of cancer cells with SC while leaving healthy tissue unaffected. Materials/Methods: Utilizing in vitro and in vivo models, we targeted centrosomal clustering in human KRAS mutant lung cancer cell lines pharmacologically with griseofulvin, a nontoxic antifungal drug shown to inhibit centrosomal clustering. Centrosomal clustering was also targeted genetically, by knockdown of the centrosomal clustering gene HSET. Knockdown of HSET, a minus-end directed motor protein, leads to multipolar spindle formation and cell death in multiple cancer cell lines. We examined the effect of griseofulvin and HSET knockdown with and without radiation on in vitro cell viability, clonogenic survival, and immunofluorescence. Using a hind-flank H358 xenograft model, we are looking at tumor growth delay, proliferation, cell death, and centrosomal clustering changes following griseofulvin treatment with or without radiation. Results: Using 3 NSCLC cell lines (A549, H358, and H460) as well as a control non-cancer cell line (HBEC) we showed that, in a concentrationdependent manner, griseofulvin can induce multipolar spindles in lung cancer cell lines using immunofluorescence co-staining of pericentrin and a-tubulin (Table 1). We observed decreased cell viability by trypan blue and increased apoptosis in lung cancer cells as determined by cleaved caspase-3 protein levels. Griseofulvin preferentially sensitized lung cancer cells to ionizing radiation but not HBEC cells as shown by clonogenic assay with an enhancement ratio of 1.14-1.46 (P<0.05 by ttest). HSET was shown to have increased expression in lung cancer cells that could be effectively knocked down by 40-67% (P < 0.05) with siRNA. Conclusion: Our data shows promising results that inhibition of centrosomal clustering forces lung cancer cells with SC into lethal multipolar divisions that are also radiosensitizing. Further study is needed to determine the potential of centrosomal clustering inhibition and radiation as a novel treatment for lung cancer. Author Disclosure: N. Raman: None. G. Lemtiri-Chlieh: None. K. Nugent: None. M. Ballew: None. T. Peck: None. M. Levine: None. R. Malek: None. H. Wang: None. A. Annadanam: None. K. Taparra: None. A. Holland: None. P.T. Tran: Research Grant; NIH-NCI, ACS, Kimmel Foundation, Astellas-Medivation, American Lung Association,

ePoster Sessions S213 Abstract 1098; Table 1 Cell Type HBEC

A549

H460

H358

Griseofulvin Concentration (mM)

% Multipolar Spindles

0 10 30 0 10 30 0 10 30 0 10 30

1.78 10.33 16.70 2.31 7.33 40.18 2.67 18.23 79.68 3.56 16.04 62.00

P value 0.0003 <0.0001 <0.0001 <0.0001

Movember-PCF, PCORI. Honoraria; Dendreon. Advisory Board; AstellasMedivation, Dendreon. Travel Expenses; Dendreon. Patent/License Fees/ Copyright; Compounds and Methods of Use in Ablative RT, Natsar Pharmaceuticals; RSNA R&E Foundation.

1099 Clinical Outcomes of Breast Proton Radiation Therapy: A Multi-institutional Analysis of the Proton Collaborative Group Registry R. Fega,1 C.E. Vargas,1 W.F. Hartsell,2 G.L. Larson,3 L.M.C. Fang,4 E.M. Nichols,5 L.R. Rosen,6 C.J. Rossi,7 and H.K. Tsai8; 1Mayo Clinic, Phoenix, AZ, 2Proton Collaborative Group, Warrenville, IL, 3ProCure Proton Therapy Center, Oklahoma City, OK, 4Seattle Cancer Care Alliance, Seattle, WA, 5University of Maryland School of Medicine, Baltimore, MD, 6Willis-Knighton Proton Therapy Center, Shreveport, LA, 7 Scripps, San Diego, CA, 8ProCure Proton Therapy Center, Somerset, NJ Purpose/Objective(s): The aim of this study was to determine disease specific outcomes and toxicities associated with proton radiotherapy (RT) for the treatment of breast cancer. Materials/Methods: The records of 335 breast cancer patients treated in a multi-institutional prospective registry were used for the present analysis between 2011 and 2016. Acute toxicity was defined as any adverse event (AE) occurring within 6 months of the start of radiotherapy. Late toxicity was defined as any event beginning or persisting for 6 months or longer from the start of radiotherapy. All AEs were measured using CTCV AE V4.0. Cancer specific failures were measured from the completion date of radiotherapy. Eighty-four percent of patients were treated with double scatter and 16% were treated with spot scanning. Results: Median follow-up was 1.1 years (range 0.2-3.7 years), with 73% of patients having follow-up of greater than 6 months, and 21% of patients with follow-up of greater than 2 years. Pathological nodal stage was pN1-3 in 68% of patients. Overall, 52 patients received prior RT. Proton RT was delivered to 36 patients using accelerated partial breast irradiation (APBI) to a total median dose of 40 Gy RBE over 10 treatments; and 299 patients were treated to the intact breast (38% ) or chest wall (62%) to a total median dose of 45 Gy RBE (range: 40 Gy-66 Gy RBE). Of the patients treated to the intact breast or chest wall, 92% included nodal irradiation. Deaths occurred in 13.7% of patients with a median of 1.9 years (0.5-3.2 years). Loco-regional failures were seen in 2.7% of patients. Distant failures were seen in 7.5% of patients with a median time to failure of 0.5 years (range: 0.2-3.3 years). Acute grade 2 toxicity was seen in 67% of patients (most commonly radiation

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International Journal of Radiation Oncology  Biology  Physics

dermatitis and/or pain), with 94% symptoms resolving within 6 months, and 1% of patients reporting persistent symptoms after one year. Acute grade 3 toxicity (most commonly radiation dermatitis and/or pain) was seen in 9.2% at a median time of 1.6 months. Chronic grade 3 toxicities were seen in 0.5% (n Z 3) of patients including late radiation dermatitis, lymphedema, and infection. Of the 3 chronic AEs, only one was seen in a patient without prior RT. Similar rates of grade 3 AEs were seen with double scatter versus spot scanning treatment. No grade 3 AEs were seen with APBI. Conclusion: This is one of the largest experiences with proton radiotherapy for breast cancer. Although acute grade 2 or higher events were relatively common, symptoms improved within 6 months. Most patients had no radiation related adverse events persisting or appearing after 6 months, including chronic grade 3 toxicity. These finding suggest that proton therapy for breast cancer provides excellent local control and low rates of late toxicities. Author Disclosure: R. Fega: None. C.E. Vargas: Independent Contractor; Florida Radiation Oncology Group. Stock; View Ray; Proton Collaborative Group. W.F. Hartsell: Partner; Radiation Oncology Consultants, Ltd. Minority owner of GammaKnife equipment; Elk Grove Radiosurgery Inc. I am a minority shareholder in a partnership for the proton therapy facility in the Chicago area; Chicago Proton Therapy Investment. Partnership; Chicago Proton Therapy Investment, Elk Grove Radiosurgery Inc., Illinois CyberKnife. G.L. Larson: None. L. Fang: None. E.M. Nichols: None. L.R. Rosen: Independent Contractor; LSU Medical School Shreveport, LA. Partner; Radiation Oncology Services. Honoraria; Iba, Lane R Rosen. Speaker’s Bureau; Lane R Rosen. Travel Expenses; Iba, Lane R Rosen. Stock; Tomotherapy/Acuray. Organizer of meetings; Caddo Bossier Cancer Foundation League. C. Rossi: None. H.K. Tsai: None.

guidelines). Based upon the ASTRO Consensus Statement guidelines for APBI (2009) applied retrospectively, 15 were suitable (33%), 27 cautionary (60%), and 3 unsuitable (7%). Freedom from local recurrence (FFLR), regional recurrence (FFRR), distant metastasis (FFDM), contralateral breast cancer (CLBC), disease-free survival (DFS), causespecific survival (CSS), and overall survival (OS) were assessed by Kaplan-Meier. Toxicities were scored using CTCAE v3.0. Cosmetic rating was scored via the Harvard criteria. Results: Median follow-up was 9.4 years. Fourteen patients were followed  10 yrs (31%) and 17 with follow-up of 9.0 - 9.9 yrs (38%). Median age was 66 yrs (48-83 yrs) with most having T1 tumors (96%) [median size 0.6cm]; all had margins with no tumor on ink. A minority (4%) had positive regional nodes. ER positivity was found in 73%. Endocrine therapy was received by 61%, while 18% had chemotherapy. Clinical outcomes revealed FFLR 97.4%, FFRR 100%, FFDM 92.9%, CLBC 97.4%, DFS 90.3%, CSS 97.6%, and OS 79.0%, all 10-year actuarial. Late toxicities analyzed included skin pigmentation, edema, and pain (all grade 1/2) along with telangiectasias, induration (Table 1), fat necrosis, seroma and rib fracture. No grade 3 or 4 toxicities were noted except for 2% grade 3 telangiectasias and 2% grade 3 induration. Fat necrosis was seen in 14% and persistent seroma in 17%. Rib fracture was seen in 3 (7%) where 160% of the prescription dose was accepted during this treatment era. Cosmesis was good/excellent in 88% at 10 years. Conclusion: With median follow-up approaching 10 years, 2-day APBI demonstrates excellent clinical effectiveness, minimal late morbidity, and good/excellent cosmesis in the majority of patients. Dose constraints such as to ribs/chest wall have been refined from these results. Short-course APBI affords appropriately selected early-stage breast cancer patients irradiation in 2 days vs several weeks of whole breast external beam treatments. Further follow-up of 2-day APBI patients will be needed to substantiate these long-term findings.

1100 Long-Term Clinical Outcomes, Late Toxicities, and Cosmetic Results of Short-Course Two-Day Brachytherapy Accelerated Partial Breast Irradiation P.Y. Chen,1 M. Wallace,2 H. Ye,2 M.S. Jawad,1 J.T. Dilworth,1 B. Wilkinson,3 N.S. Dekhne,4 P.R. Benitez,4 and G.S. Gustafson5; 1 Beaumont Health System, Royal Oak, MI, 2Beaumont Health, Royal Oak, MI, 3Willis-Knighton Cancer Center, Shreveport, LA, 4Breast Care Center, Beaumont Health System, Royal Oak, MI, 5Beaumont Health System, Sterling Heights, MI Purpose/Objective(s): Hypofractionated radiotherapy is increasingly being adopted for early-stage breast cancer. To assess the long-term outcome of 2-day brachytherapy accelerated partial breast irradiation [2dAPBI], we analyzed patients so treated for clinical effectiveness, late toxicity, and cosmetic results. Materials/Methods: Between 3/2004 and 8/2007, 45 patients were treated with single-lumen applicator-based 2d-APBI [700 cGy BID x 4]. Updated thru 1/2017, an IRB-approved retrospective review was done. Selection criteria included age >40, 3.0 cm tumor size, 3 pathologically positive lymph nodes, and negative margins (per NSABP

Abstract 1100; Table 1

Chronic toxicities with 2-day APBI (n Z 42)

Toxicity Grade

Grade 0

Grade 1

Grade 2

Hyperpigmentation Hypopigmentation Breast Pain Breast Edema Induration/Fibrosis Telangiectasia

24 (57%) 37 (88%) 26 (60%) 28 (67%) 7 (17%) 28 (67%)

17 (41%) 5 (12%) 14 (33%) 12 (28%) 14 (33%) 6 (14%)

1 (2%) 2 (5%) 2 (5%) 20 (48%) 7 (17%)

Grade 3

1 (2%) 1 (2%)

Author Disclosure: P.Y. Chen: Stock; Greater Michigan Gamma Knife (GMGK). M. Wallace: ASTRO, Metro Detroit Oncology Nursing Society. H. Ye: None. M.S. Jawad: None. J.T. Dilworth: None. B. Wilkinson: Independent Contractor; Provision Center for Proton Therapy. Honoraria; Accuray, American Society of Clinical Oncology, Novocure. Advisory Board; Radiating Hope. Travel Expenses; Accuray, American College of Radiation Oncology, American Society of Clinical Oncology; Radiating Hope. Responsible for programming and education within organization. N.S. Dekhne: None. P.R. Benitez: None. G.S. Gustafson: None.