Impact of EML4-ALK Variant on Resistance Mechanisms and Clinical Outcomes in ALK-Positive Lung Cancer

Purpose Advanced anaplastic lymphoma kinase ( ALK) fusion-positive non-small-cell lung cancers (NSCLCs) are effectively treated with ALK tyrosine kinase inhibitors (TKIs). However, clinical outcomes in these patients vary, and the benefit of TKIs is limited as a result of acquired resistance. Emerging data suggest that the ALK fusion variant may affect clinical outcome, but the molecular basis for this association is unknown. Patients and Methods We identified 129 patients with ALK-positive NSCLC with known ALK variants. ALK resistance mutations and clinical outcomes on ALK TKIs were retrospectively evaluated according to ALK variant. A Foundation Medicine data set of 577 patients with ALK-positive NSCLC was also examined. Results The most frequent ALK variants were EML4-ALK variant 1 in 55 patients (43%) and variant 3 in 51 patients (40%). We analyzed 77 tumor biopsy specimens from patients with variants 1 and 3 who had progressed on an ALK TKI. ALK resistance mutations were significantly more common in variant 3 than in variant 1 (57% v 30%; P = .023). In particular, ALK G1202R was more common in variant 3 than in variant 1 (32% v 0%; P < .001). Analysis of the Foundation Medicine database revealed similar associations of variant 3 with ALK resistance mutation and with G1202R ( P = .010 and .015, respectively). Among patients treated with the third-generation ALK TKI lorlatinib, variant 3 was associated with a significantly longer progression-free survival than variant 1 (hazard ratio, 0.31; 95% CI, 0.12 to 0.79; P = .011). Conclusion Specific ALK variants may be associated with the development of ALK resistance mutations, particularly G1202R, and provide a molecular link between variant and clinical outcome. ALK variant thus represents a potentially important factor in the selection of next-generation ALK inhibitors.

Differential Association Between Circulating Lymphocyte Populations With Outcome After Radiation Therapy in Subtypes of Liver Cancer

PURPOSE

Irradiation may have significant immunomodulatory effects that impact tumor response and could potentiate immunotherapeutic approaches. The purposes of this study were to prospectively investigate circulating lymphoid cell population fractions during hypofractionated proton therapy (HPT) in blood samples of liver cancer patients and to explore their association with survival.

METHODS AND MATERIALS

We collected serial blood samples before treatment and at days 8 and 15 of HPT from 43 patients with liver cancer-22 with hepatocellular carcinoma (HCC) and 21 with intrahepatic cholangiocarcinoma (ICC)-enrolled in a phase 2 clinical trial. All patients received 15 fractions of proton therapy to a median dose of 58 Gy (relative biological effectiveness). We used flow cytometry to measure the changes in the fractions of total CD3⁺, CD4⁺, and CD8⁺ T cells; CD4⁺ CD25⁺ T cells; CD4⁺ CD127⁺ T cells; CD3⁺ CD8⁺ CD25⁺ activated cytotoxic T lymphocytes (CTLs); and CD3^- CD56⁺ natural killer cells.

RESULTS

With a median follow-up period of 42 months, median overall survival (OS) in the study cohort was 30.6 months for HCC and 14.5 months for ICC patients. Longer OS was significantly correlated with greater CD4⁺ CD25⁺ T-cell (P = .003) and CD4⁺ CD127⁺ T-cell (P = .01) fractions at baseline only in ICC patients. In HCC patients, the fraction of activated CTLs mid treatment (at day 8) was significantly associated with OS (P = .007). These findings suggest a differential relevance of immunomodulation by HPT in these liver cancers.

CONCLUSIONS

Antitumor immunity may depend on maintenance of a sufficiently high number of activated CTLs during HPT in HCC patients and CD4⁺ CD25⁺ T cells and CD4⁺ CD127⁺ T cells prior to treatment in ICC patients. These results could guide the design of future studies to determine the optimal treatment schedules when combining irradiation with specific immunotherapy approaches.

Asymptomatic Late-phase Radiographic Changes Among Chest-Wall Patients Are Associated With a Proton RBE Exceeding 1.1

PURPOSE

Clinical practice assumes a fixed proton relative biological effectiveness (RBE) of 1.1, but in vitro experiments demonstrate higher RBEs at the distal edge of the proton spread-out Bragg peak, that is, in a region that falls within the lung for chest-wall patients. We performed retrospective qualitative and quantitative analyses of lung-density changes-indicative of asymptomatic fibrosis-for chest-wall patients treated with protons or photons. Our null hypothesis was that, assuming a fixed RBE of 1.1, these changes would be the same for the 2 cohorts, supporting current RBE practice. Our alternative hypothesis was that radiographic abnormalities would be greater for the proton cohort, suggesting an RBE > 1.1.

METHODS AND MATERIALS

We analyzed follow-up computed tomography (CT) scans for 20 proton and photon patients. All were prescribed 50.4 Gy (RBE) in 28 fractions, assuming a fixed RBE of 1.1 for protons and 1 for photons. Deformable registrations enabled us to calculate density changes in the normal lung, specifically (1) median Hounsfield unit (HU) values among posttreatment CT scans and (2) changes in median HU values between pretreatment and posttreatment CT scans, both as a function of grays (RBE). In addition, qualitative abnormality grading was performed by a radiologist.

RESULTS

Proton patients exhibited higher values of HU/Gy (RBE) (endpoint 1) and ΔHU/Gy (RBE) (endpoint 2): P = .049 and P = .00019, respectively, were obtained (likelihood ratio tests of full linear mixed-effects models against models without "modality"). Furthermore, qualitative radiologic scoring indicated a significant difference between the cohorts (Wilcoxon P = .018; median score, 3 of 9 for protons and 1.5 of 9 for photons).

CONCLUSIONS

Our data support the hypothesis that the proton RBE for lung-density changes exceeds 1.1. This RBE elevation could be attributable to (1) the late, normal tissue endpoint that we consider or (2) end-of-range proton linear energy transfer elevation-or a combination of the two. Regardless, our results suggest that variations in proton RBE prove important in vivo as well as in vitro.

Abstract P2-11-04: Not presented

This abstract was not presented at the symposium.

A pilot feasibility study of definitive concurrent chemoradiation with pencil beam scanning proton beam in combination with 5-fluorouracil and mitomycin-c for carcinoma of the anal canal

733

Background: Definitive chemoradiation (CRT) with concurrent 5-fluorouracil (5-FU)/mitomycin C (MMC) for anal cancer yields high rates of long term survival. However, CRT has significant acute and long term toxicity. Pencil beam scanning proton beam (PBS-PT) may potentially reduce this toxicity. This is a pilot study evaluating the feasibility of definitive concurrent CRT with PBS-PT with 5-FU/MMC for anal cancer. Methods: Pts were enrolled on an NCI sponsored, prospective, multi-institutional, pilot study (NCT 01858025). Key eligibility were ECOG 0-2, age 18+, invasive SCC of the anal canal, clinically staged T1-4, N0-3. Pts were treated per RTOG 0529 RT schema; for T1-2, N0: 50.4 Gy to primary CTV, 42 Gy to elective LNs; for T3+ or N+: 54 Gy to primary CTV, 50.4-54 Gy to involved LN, and 45 Gy to elective LNs. Pts received 5-FU/MMC on day 1 and 29. The primary objective of this study was to determine feasibility of PBS-PT with 5-FU/MMC, determined if grade 3+ dermatologic toxicity is < 48% (grade 3+ dermatologic toxicity from RTOG 98-11). The secondary endpoint was rates of overall grade 3+ toxicities, clinical complete response (cCR) rate and patterns of local regional tumor recurrence. Results: Between February 2014 to April 2017, we enrolled 25 patients into our study, all of whom were analyzed. 23 pts (92%) completed treatment per protocol, 2 pts died on treatment due to underlying comorbidities. Median time to completion of treatment was 42 days (range 38-49). The Grade 3+ radiation dermatitis was 24% (Table 1). With a median follow-up of 17.6 months (range 7.7-42.0) among the 21 patients still alive, the 1 year local control, progression-free survival, and overall survival are 100%, 83% and 87%, respectively. Conclusions: In our prospective, pilot study of PBS-PT with concurrent 5-FU/MMC, PBS-PT was found to be feasible. While felt to be unrelated to the study, the two Grade 5 adverse events on this small study highlights potentially treatment related risks of this effective yet toxic regimen. Clinical trial information: NCT01858025. [Table: see text]

Phase II Study of Proton-Based Stereotactic Body Radiation Therapy for Liver Metastases: Importance of Tumor Genotype

Background

We evaluated the efficacy and safety of risk-adapted, proton-based stereotactic body radiation therapy (SBRT) for liver metastases from solid tumors.

Methods

This single-arm phase II single institutional study (NCT01239381) included patients with limited extrahepatic disease, 800 mL or greater of uninvolved liver, and no cirrhosis or Child-Pugh A, who had received proton-based SBRT to one to four liver metastases from solid tumors. Treatment comprised 30 to 50 Gray equivalent (GyE) in five fractions based on the effective volume of liver irradiated. Sample size was calculated to determine if local control (LC) at one year was greater than 70%. The cumulative incidence of local failure was used to estimate LC. The association of tumor characteristics, including genetic alterations in common cancer genes such as BRAF, EGFR, HER2, KRAS, NRAS, PIK3CA, and TP53 with local tumor control, was assessed. All statistical tests were two-sided.

Results

Eighty-nine patients were evaluable (colorectal, n = 34; pancreatic, n = 13; esophagogastric, n = 12; other, n = 30). Median tumor size was 2.5 cm (range = 0.5-11.9 cm). Median dose was 40 GyE (range = 30-50 GyE), and median follow-up was 30.1 months (range = 14.7-53.8 months). There was no grade 3 to 5 toxicity. Median survival time was 18.1 months. The one- and three-year LC rates were 71.9% (95% confidence limit [CL] = 62.3% to 80.9%) and 61.2% (95% CL = 50.8% to 71.8%), respectively. For large tumors (≥6 cm), one-year LC remained high at 73.9% (95% CL = 54.6% to 89.8%). Mutation in the KRAS oncogene was the strongest predictor of poor LC (P = .02). Tumor with both mutant KRAS and TP53 were particularly radioresistant, with a one-year LC rate of only 20.0%, compared with 69.2% for all others (P = .001).

Conclusions

We report the largest prospective evaluation to date of liver SBRT for hepatic metastases, and the first with protons. Protons were remarkably well tolerated and effective even for metastases that were 6 cm or larger. KRAS mutation is a strong predictor of poor LC, stressing the need for tumor genotyping prior to SBRT and treatment intensification in this patient subset.

Patterns of Metastatic Spread and Mechanisms of Resistance to Crizotinib in ROS1-Positive Non-Small-Cell Lung Cancer

PURPOSE

The ROS1 tyrosine kinase is activated through ROS1 gene rearrangements in 1-2% of non-small cell lung cancer (NSCLC), conferring sensitivity to treatment with the ALK/ROS1/MET inhibitor crizotinib. Currently, insights into patterns of metastatic spread and mechanisms of crizotinib resistance among ROS1-positive patients are limited.

PATIENTS AND METHODS

We reviewed clinical and radiographic imaging data of patients with ROS1- and ALK-positive NSCLC in order to compare patterns of metastatic spread at initial metastatic diagnosis. To determine molecular mechanisms of crizotinib resistance, we also analyzed repeat biopsies from a cohort of ROS1-positive patients progressing on crizotinib.

RESULTS

We identified 39 and 196 patients with advanced ROS1- and ALK-positive NSCLC, respectively. ROS1-positive patients had significantly lower rates of extrathoracic metastases (ROS1 59.0%, ALK 83.2%, P=0.002), including lower rates of brain metastases (ROS1 19.4%, ALK 39.1%; P = 0.033), at initial metastatic diagnosis. Despite similar overall survival between ALK- and ROS1-positive patients treated with crizotinib (median 3.0 versus 2.5 years, respectively; P=0.786), ROS1-positive patients also had a significantly lower cumulative incidence of brain metastases (34% vs. 73% at 5 years; P<0.0001). Additionally, we identified 16 patients who underwent a total of 17 repeat biopsies following progression on crizotinib. ROS1 resistance mutations were identified in 53% of specimens, including 9/14 (64%) non-brain metastasis specimens. ROS1 mutations included: G2032R (41%), D2033N (6%), and S1986F (6%).

CONCLUSIONS

Compared to ALK rearrangements, ROS1 rearrangements are associated with lower rates of extrathoracic metastases, including fewer brain metastases, at initial metastatic diagnosis. ROS1 resistance mutations, particularly G2032R, appear to be the predominant mechanism of resistance to crizotinib, underscoring the need to develop novel ROS1 inhibitors with activity against these resistant mutants.

Prospective, Randomized Study of Radiation Dose Escalation With Combined Proton-Photon Therapy for Benign Meningiomas

PURPOSE

To assess the outcomes of benign meningiomas (BM) treated to two radiation dose levels.

METHODS AND MATERIALS

We randomly assigned patients (1:1) with incompletely resected or recurrent BM to 2 radiation doses: 55.8 Gy(relative biological effectiveness [RBE]) and 63.0 Gy(RBE) of fractionated combined proton-photon radiation therapy. The primary endpoint was local control with hypothesis of improved tumor control with higher dose. Secondary endpoints included progression-free survival, overall survival, and rates of treatment-related toxicities.

RESULTS

Between 1991 and 2000, 47 patients were randomized. Three patients were excluded for nonbenign histology; therefore, 44 patients were analyzed: 22 who received 55.8 Gy(RBE) and 22 who received 63.0 Gy(RBE). The median follow-up was 17.1 years. Local control for the entire cohort was 98% at 10 years and 90% at 15 years. Of the 5 patients with local recurrence, 4 occurred after 10 years of follow-up, and 3 were in the lower dose group (P=.322). In the modified intention to treat analysis, there was no difference in progression-free survival (P=.234) and overall survival (P=.271) between arms. A total of 26 patients (59%) experienced a grade 2 or higher late toxicity, including 9 patients (20%) incurring a cerebrovascular accident (CVA), 7 of which were deemed at least possibly attributable to irradiation. The median time between completion of radiation therapy and CVA was 5.6 years (range, 1.4-14.0 years).

CONCLUSIONS

Fractionated combined proton-photon radiation therapy is effective for BM, with no apparent benefit in dose escalation. Further investigation is needed to better define the risk of late toxicities, including CVA after cranial radiation therapy.

Phase II study of autophagy inhibition with hydroxychloroquine (HCQ) and preoperative (preop) short course chemoradiation (SCRT) followed by early surgery for resectable ductal adenocarcinoma of the head of pancreas (PDAC)

4118

Background: PDAC is highly dependent on autophagy, a metabolic process that renders cancer cells resistant to cytotoxic therapies. HCQ is an inhibitor of autophagy, and has preclinical activity in PDAC. We evaluate the efficacy of concurrent and adjuvant HCQ with preop SCRT and adjuvant chemotherapy in early, resectable PDAC. Methods: Pts with radiographically resectable, biopsy-proven PDAC of the head were enrolled from 12/2011-9/2016 on this IRB-approved, NCI-sponsored clinical trial (NCT01494155). Eligibility included no involvement of SMA or celiac artery on CT; adequate renal, hepatic and hematopoetic function; and ECOG PS 0/1. SCRT was 5 Gy x 5 with protons or 3 Gy x 10 with photons concurrent with Cape 825 mg/m2 BID wk 1 and 2 M-F. HCQ was started at 400 mg po BID 1 wk prior to radiation through SCRT until the day of surgery. Surgery was performed 1-3 wks after completion of SCRT. Pts were recommended to receive 6 mo of gemcitabine-based chemotherapy after surgery. Pts resumed HCQ after discharge from surgery and continued until progression. Follow-up was performed every 3 months with CT scanning every 6 mo. Sample size of 50 to evaluate an increase of 2-year PFS from 30% to 45%. Results: 50 pts were enrolled on study and all are evaluable for this analysis. Median age- 69 (range 54-86); pre-treatment CA19-9 median 69.5 U/mL ( < 1-10235), female- 24 pts (48%). Gr 3 toxicity was noted in 2 (4%) pts (nausea-1, hyperglycemia-1). All 50 pts completed SCRT. 46 pts underwent resection. Reasons for no resections: metastatic disease-2, toxicity-1, intercurrent illness- 1. 38 pts had R0 resection, 8 had R1 resection. 29 of 46 pts had positive nodes. 1 pt achieved pathologic complete response (CR), 2 pts had near CR . 11 pts remain on HCQ. Median follow up in 26 surviving pts is 18.3 months. mPFS is 11.7 mo, mOS 23.3 mo. OS-2 yr- 43.1%, PFS-2-yr 32.0%. Conclusions: HCQ with preop SCRT and adjuvant gemcitabine-based chemotherapy is well tolerated but did not meaningfully impact DFS. Further pathologic/correlative studies, particularly in outstanding pathologic responders and long term survivors are ongoing. Clinical trial information: NCT01494155.

Retrospective analysis of clinical outcomes of early stage ALK-positive (ALK+) non-small cell lung cancer (NSCLC)

8536

Background: ALK rearrangements are important oncogenic drivers in NSCLC. However, the prognostic implications of these rearrangements are unclear due to 1) conflicting results from small series of patients (pts) with early-stage ALK+ NSCLC, and 2) use of highly effective ALK tyrosine kinase inhibitors (TKI) in the metastatic setting. To assess the prognostic significance of ALK rearrangements in resected NSCLC, we performed a retrospective analysis of survival outcomes among pts with resected ALK+, EGFR+, or KRAS+ NSCLC treated at two institutions. Methods: We reviewed charts of pts that underwent resection for stage 1-3 NSCLC at Massachusetts General Hospital or Memorial Sloan Kettering Cancer Center between 1/2009 and 12/2012. Recurrence-free survival (RFS) was estimated for each genotype. Results: Among 764 pts (480 KRAS+, 255 EGFR+, 29 ALK+), we identified 555 (73%), 101 (13%), and 108 (14%) pts with stage I, 2, and 3 NSCLC, respectively. ALK+ pts were distributed across all stages: 10 (34%) stage I, 6 (21%) stage 2, and 13 (45%) stage 3 NSCLCs. Chemotherapy was administered to 14 ALK+ ( 0% stage 1, 67% stage 2, 77% stage 3), 45 EGFR+ (3% stage 1, 44% stage 2, 81% stage 3), and 96 KRAS+ pts (4% stage 1, 56% stage 2, 71% stage 3), respectively, for early-stage NSCLC. Thirteen (7%) stage 1 EGFR+ patients received adjuvant EGFR TKI. Although median RFS was not reached for EGFR+ pts, it was 24.3 months (95%CI 11.4 to 65.3) for ALK+ pts and 72.9 months (95%CI 59.7 to undefined) for KRAS+ pts. RFS for ALK+ NSCLC was significantly shorter than the other groups (HR 2.9, 95%CI: 1.75-4.89 vs. EGFR and HR 1.8, 95%CI: 1.12-2.93 vs. KRAS). When adjusted for stage, ALK+ NSCLC remained associated with worse RFS compared to EGFR+ NSCLC (HR 1.8, 95%CI: 1.09-3.12), but not when compared to KRAS+ NSCLC (HR 1.30, 95%CI: 0.79-2.12). Conclusions: Early stage ALK+ NSCLC is associated with shorter RFS than EGFR+ NSCLC. The propensity for relapse and the significant anti-tumor activity of ALK TKIs in pts with metastatic NSCLC suggest that enrollment of patients on trials of adjuvant ALK TKIs should be prioritized.

Effect of FAK inhibitor defactinib on tumor immune changes and tumor reductions in a phase II window of opportunity study in malignant pleural mesothelioma (MPM)

8555

Background: Defactinib is an oral Focal Adhesion Kinase (FAK) inhibitor with preclinical activity in MPM. We assessed responses to defactinib treatment prior to planned surgical resection in naive patients with MPM. Methods: Three cohorts of 10 participants each received defactinib 400mg BID for 12, 35 and 21 days. Pre- and post-treatment blood, tumor biopsies and imaging were obtained for biomarker, immune cell and tumor response (modified RECIST, Tumor volume and SUV max) assessment. Toxicity was monitored for 30 days post treatment. Results: Between 12/2013 and 12/2017, 31 participants were registered at our center; 1 withdrew prior to intervention. Among 30 treated, 24 (80%) were male; median age 70 (47-83) years; surgery was EPP 7%, complete pleurectomy decortication (PD) 10%, extended PD 60%, partial PD 10%, unresectable 13%; MPM subtype was epithelioid 67%, biphasic 17%, sarcomatoid 17%. Expected complications of FAK inhibition, diagnostic/staging/operative procedures occurred in 83% (grade 1, 30%; grade 2, 43%; grade 3, 10%). Unexpected adverse events occurred in 77% (grade 1, 63%; grade 2, 20%; grade 3, 17% [wound-infection, prolonged QT interval, and hyperglycemia in 3% each; increased INR in 7%]; grade 5, 7% [due to progressive disease in 3%, intraoperative anaphylactoid reaction unrelated to the drug in 3%]). Objective partial response was observed in 13%, stable disease in 67%, progression in 17%. Tumor volume decreased 3-72% in 47% patients and increased 1-82% in 53%. SUV max decreased 3-69% in 50% and increased 1-61% in 50%. Biological correlates of treatment included target inhibition (75% pFAK reduction); tumor immune microenvironment changes: increased naïve (CD45RA+PD-1+CD69+) CD4 and CD8 T cells, reduced myeloid and Treg immuno-suppressive cells, reduced exhausted T cells (PD-1+CD69+), reduced peripheral MDSCs; and histological subtype change (pleomorphic or biphasic to epithelioid) in 13% of cases. Conclusions: Brief preoperative defactinib exposure was well tolerated, did not alter resectability or mortality compared to prior series, and showed evidence of therapeutic and immunomodulatory effects. Clinical trial information: NCT02004028.

FOLFIRINOX (F-NOX) followed by individualized radiation for borderline-resectable pancreatic cancer (BRPC): Toxicity, R0 resection, and interim survival data from a prospective phase II study

4113

Background: F-NOX is increasingly utilized in BRPC as neoadjuvant therapy. However, prospective data remains limited; the largest series is a 22 patient (pt) cooperative group trial (Alliance A021101), in which 14 pts had R0 resection. In this study, we evaluate neoadjuvant F-NOX followed by individualized chemoradiation (CRT) for BRPC. Methods: Pts ECOG PS 0-1 with biopsy-proven BRPC defined by NCCN criteria were enrolled in a single institution, NCI-sponsored phase II study (NCT01591733). Pts received F-NOX for 8 cycles. If after chemotherapy the tumor was radiographically resectable, pts received short course CRT in 5 (protons 25 GyE) or 10 fractions (photons 30 Gy) with capecitabine 825 mg/m2 bid. If the tumor was still abutting vasculature, pts received CRT to 50.4 Gy with a vascular boost to 58.8 Gy. Primary endpoint was R0 resection rate. Results: 50 pts were enrolled from 8/2012 to 8/2016. Two pts were ineligible (lung metastasis, negative biopsy); 48 pts were evaluable. Median age was 62y (46-74). Median tumor size was 37 mm (21-56). Thirty-six pts (75%) had pancreatic head tumors. Median follow up was 18.2 months among 31 patients still alive. Of the evaluable pts, 40 (83%) completed therapy. Reasons for not completing therapy include pt withdrawal (3), physician decision (3), unacceptable toxicity (1) and progression (1). Grade 3 or greater toxicity occurred in 48% of pts, but no individual grade 3 toxicity exceeded 15%. Twenty-seven pts (56%) had short course CRT, while 13 pts (27%) had long course CRT. Twenty-nine pts were resected; R0 resection was achieved in 28/29 (96.5%). R0 resection rate among all evaluable pts was 58.3%. Median PFS among all evaluable pts was was 14.7 months; mOS was 37.7 months, with 1y OS 79.5% and 2y OS 59.3%. Among resected patients, mOS has not been reached. 1y PFS was 78.1% and 2y PFS 55.4%; 1y OS was 92.6% and 2y OS was 80.6%. Conclusions: Preoperative F-NOX followed by individualized chemoradiation in BRPC results in high R0 resection rates as well as prolonged mPFS and mOS in this large prospective cohort. Clinical trial information: NCT01591733.

FOLFIRINOX (F-NOX) followed by individualized radiation for borderline-resectable pancreatic cancer: Preliminary toxicity and R0 resection rates from a prospective phase II study

368

Background: F-NOX has been increasingly utilized in borderline resectable pancreatic cancer (BRPC) due to the improved response rate compared to gemcitabine. However, prospective data remains limited, with the largest series being a 22 patient (pt) cooperative group trial (Alliance A021101), in which 14 pts had R0 resection. In this study, we evaluate neoadjuvant F-NOX followed by individualized chemoradiation (CRT) for BRPC. Methods: Pts ECOG PS 0-1 with biopsy-proven BRPC as defined by NCCN criteria (SMV/PV involvement with suitable flow, abutment of SMA < 180 degrees or of hepatic artery) were enrolled in a single institution, NCI-sponsored phase II study (NCT01591733). Pts received F-NOX for 8 cycles. If after chemotherapy, the tumor was radiographically resectable, pts received short course CRT in 5 (protons 25 GyE) or 10 fractions (photons 30 Gy) with capecitabine 825 mg/m2 bid. If the tumor was still abutting vasculature, pts received CRT to 50.4 Gy with a vascular boost to 58.8 Gy. The primary endpoint of the study was R0 resection rate. Results: 50 pts were enrolled from 8/2012 to 8/2016. One pt was ineligible (lung metastases) and 1 pt is still on treatment, thus 48 patients were evaluable for this analysis. Median age was 62y (46-74). Median tumor size was 37 mm (21-56). Tumor location was in the head of pancreas for 36 (75%) pts. Of the evaluable pts, 40 (83%) completed therapy. Reasons for not completing therapy included pt withdrawal (3), physician decision (3), unacceptable toxicity (1) and progression (1). Grade 3 or greater toxicity occurred in 21 (44%) pts, including diarrhea (6, 12%), febrile neutropenia (4, 8.5%), neutropenia (4, 8.5%), elevated AST/ALT (3, 6.2%), thrombocytopenia (2, 4.2%), anemia (2, 4.2%), elevated alkaline phosphatase (2, 4.2%). 27 (56%) had short course CRT, while 13 (27%) had long course CRT. In evaluable pts, R0 resection rate was 28/40 (58%). Conclusions: Preoperative F-NOX followed by individualized chemoradiation results in a high R0 resection rate. Final results including PFS outcomes on the entire cohort will be presented at the meeting. Clinical trial information: NCT01591733.

TGF-B1 inhibition with losartan in combination with FOLFIRINOX (F-NOX) in locally advanced pancreatic cancer (LAPC): Preliminary feasibility and R0 resection rates from a prospective phase II study

386

Background: F-NOX is utilized in LAPC due to improved response over gemcitabine, with theoretical potential for curative resection. However the response rate remains well below 50%. Preclinical data suggest that inhibition of the renin-angiotensin system with losartan reduces the activity of TGF-B1, enhancing intratumoral penetration of chemotherapy by remodeling desmoplastic stroma and improving vascular perfusion. In this study, we evaluate the feasibility of adding losartan to F-NOX in LAPC. Methods: Pts ECOG PS 0-1 with LAPC (NCCN criteria) were enrolled in a single institution, NCI-sponsored phase II study (NCT01821729). Pts received F-NOX/losartan for 8 cycles. If the tumor was radiographically resectable after chemotherapy, pts received short-course chemoradiation (CRT) in 5 fractions (protons 25 GyE, capecitabine 825 mg/m2 bid). If it was still abutting vasculature, pts received CRT to 50.4 Gy with a vascular boost to 58.8 Gy. The primary endpoint was proportion of pts remaining progression-free after 8 cycles of F-NOX/losartan. Results: 32 pts were enrolled from 8/2013 to 6/2016. One pt withdrew prior to treatment, 6 pts are still receiving F-NOX/losartan or CRT. 25 were included in this analysis. Median age was 62y (46-75). Median tumor size was 42mm (22-68). Tumor was in the head of the pancreas in 16 (64%) pts. Of evaluable pts, 18 (72%) completed F-NOX/losartan followed by CRT. Reasons for discontinuation included losartan intolerance (3), failure to thrive (2), investigator discretion (1), and progression (1). Grade 3 or greater toxicity occurred in 11 (40%) pts, including diarrhea (4, 16%), thrombocytopenia (3, 12%), nausea (3, 12%), neutropenia (2, 8%), and febrile neutropenia (1, 4%). Two pts (8%) had short course CRT, 16 (64%) had long course CRT. In evaluable pts, 4 remained unresectable while one pt had R1 resection. R0 resection was achieved in 13 (52%). Conclusions: Based on the low discontinuation rate of the F-NOX/losartan combination, it met criteria for feasibility. The high R0 resection rate in the feasibility cohort has prompted expansion as a phase II study with an R0 resection endpoint. Clinical trial information: NCT01821729.

Phase 1 trial of preoperative image guided intensity modulated proton radiation therapy with simultaneously integrated boost to the high risk margin for retroperitoneal sarcomas

PURPOSE

To conduct phase 1 and 2 trials with photon intensity modulated radiation therapy and intensity modulated proton therapy (IMPT) arms to selectively escalate the retroperitoneal sarcoma preoperative radiation dose to tumor volume (clinical target volume [CTV] 2) that is judged to be at a high risk for positive margins and aim to reduce local recurrence. We report on the IMPT study arm in phase 1.

METHODS AND MATERIALS

Patients aged ≥18 years with primary or locally recurrent retroperitoneal sarcoma were treated with preoperative IMPT, 50.4 GyRBE in 28 fractions, to CTV1 (gross tumor volume and adjacent tissues at risk of subclinical disease) with a simultaneous integrated boost to CTV2 to doses of 60.2, 61.6, and 63.0 GyRBE in 28 fractions of 2.15, 2.20, and 2.25 GyRBE, respectively. The primary objective of the phase 1 study was to determine the maximum tolerated dose to CTV2, which will be further tested in the phase 2 study.

RESULTS

Eleven patients showed increasing IMPT dose levels without acute dose limiting toxicities that prevented dose escalation to maximum tolerated dose. Acute toxicity was generally mild with no radiation interruptions. No unexpected perioperative morbidity was noted. Eight months postoperatively, one patient developed hydronephrosis that was treated by stent with ureter dissected off tumor and received 57.5 GyRBE. Retained ureter(s) was (were) subsequently constrained to 50.4 GyRBE without further problem. With an 18-month median follow-up, there were no local recurrences.

CONCLUSIONS

IMPT dose escalation to CTV2 to 63 GyRBE was achieved without acute dose limiting toxicities. The phase 2 study of IMPT will accrue patients to that dose. Parallel intensity modulated radiation therapy phase 1 arm is currently accruing at the initial dose level. Ureters that undergo a high dose radiation and/or surgery are at risk for late hydro-ureter. Future studies will constrain retained ureters to 50.4 GyRBE to avoid ureteral stricture.

Validation of a Gene Expression Test for Mesothelioma Prognosis in Formalin-Fixed Paraffin-Embedded Tissues

A molecular test performed using fresh-frozen tissue was proposed for use in the prognosis of patients with pleural mesothelioma. The accuracy of the test and its properties was assessed under Clinical Laboratory Improvement Amendments-approved guidelines using FFPE tissue from an independent multicenter patient cohort. Concordance studies were performed using matched frozen and FFPE mesothelioma samples. The prognostic value of the test was evaluated in an independent validation cohort of 73 mesothelioma patients who underwent surgical resection. FFPE-based classification demonstrated overall high concordance (83%) with the matched frozen specimens, on removal of cases with low confidence scores, showing sensitivity and specificity in predicting type B classification (poor outcome) of 43% and 98%, respectively. Concordance between research and clinical methods increased to 87% on removal of low confidence cases. Median survival times in the validation cohort were 18 and 7 months in type A and type B cases, respectively (P = 0.002). Multivariate classification adding pathologic staging information to the gene expression score resulted in significant stratification of risk groups. The median survival times were 52 and 14 months in the low-risk (class 1) and intermediate-risk (class 2) groups, respectively. The prognostic molecular test for mesothelioma can be performed on FFPE tissues to predict survival, and can provide an orthogonal tool, in combination with established pathologic parameters, for risk evaluation.

Neurocognitive effects of proton radiation therapy in adults with low-grade glioma

To understand neurocognitive effects of proton radiation therapy (PRT) in patients with low-grade glioma, we evaluated 20 patients who received this therapy prospectively and over 5 years with a comprehensive neuropsychological battery. 20 patients were evaluated at baseline and at yearly intervals for up to 5 years with a battery of neuropsychological measures that assessed intellectual, attention, executive, visuospatial and memory functions as well as mood and functional status. We evaluated change in cognitive functioning over time. We analyzed the relationship between cognitive performance and tumor location and also examined whether patients' performance differed from that reported in a study of normative practice effects. Overall, patients exhibited stability in cognitive functioning. Tumor location played a role in performance; those with tumors in the left hemisphere versus in the right hemisphere were more impaired at baseline on verbal measures (p < .05). However, we found greater improvement in verbal memory over time in patients with left than with right hemisphere tumors (p < .05). Results of our study, the first to investigate, in depth, neurocognitive effects of PRT in adults with low-grade gliomas, are promising. We hypothesize that the conformal advantage of PRT may contribute to preservation of cognitive functioning, although larger sample sizes and a longer period of study are required. Our study also highlights the need to consider normative practice effects when studying neurocognitive functioning in response to treatment over time, and the need to utilize comprehensive neuropsychological batteries given our findings that differentiate patients with left and right hemisphere tumors.

EGFR Mutations and ALK Rearrangements Are Associated with Low Response Rates to PD-1 Pathway Blockade in Non-Small Cell Lung Cancer: A Retrospective Analysis

PURPOSE

PD-1 inhibitors are established agents in the management of non-small cell lung cancer (NSCLC); however, only a subset of patients derives clinical benefit. To determine the activity of PD-1/PD-L1 inhibitors within clinically relevant molecular subgroups, we retrospectively evaluated response patterns among EGFR-mutant, anaplastic lymphoma kinase (ALK)-positive, and EGFR wild-type/ALK-negative patients.

EXPERIMENTAL DESIGN

We identified 58 patients treated with PD-1/PD-L1 inhibitors. Objective response rates (ORR) were assessed using RECIST v1.1. PD-L1 expression and CD8(+) tumor-infiltrating lymphocytes (TIL) were evaluated by IHC.

RESULTS

Objective responses were observed in 1 of 28 (3.6%) EGFR-mutant or ALK-positive patients versus 7 of 30 (23.3%) EGFR wild-type and ALK-negative/unknown patients (P = 0.053). The ORR among never- or light- (≤10 pack years) smokers was 4.2% versus 20.6% among heavy smokers (P = 0.123). In an independent cohort of advanced EGFR-mutant (N = 68) and ALK-positive (N = 27) patients, PD-L1 expression was observed in 24%/16%/11% and 63%/47%/26% of pre-tyrosine kinase inhibitor (TKI) biopsies using cutoffs of ≥1%, ≥5%, and ≥50% tumor cell staining, respectively. Among EGFR-mutant patients with paired, pre- and post-TKI-resistant biopsies (N = 57), PD-L1 expression levels changed after resistance in 16 (28%) patients. Concurrent PD-L1 expression (≥5%) and high levels of CD8(+) TILs (grade ≥2) were observed in only 1 pretreatment (2.1%) and 5 resistant (11.6%) EGFR-mutant specimens and was not observed in any ALK-positive, pre- or post-TKI specimens.

CONCLUSIONS

NSCLCs harboring EGFR mutations or ALK rearrangements are associated with low ORRs to PD-1/PD-L1 inhibitors. Low rates of concurrent PD-L1 expression and CD8(+) TILs within the tumor microenvironment may underlie these clinical observations. Clin Cancer Res; 22(18); 4585-93. ©2016 AACRSee related commentary by Gettinger and Politi, p. 4539.

Multi-Institutional Phase II Study of High-Dose Hypofractionated Proton Beam Therapy in Patients With Localized, Unresectable Hepatocellular Carcinoma and Intrahepatic Cholangiocarcinoma

PURPOSE

To evaluate the efficacy and safety of high-dose, hypofractionated proton beam therapy for hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC).

MATERIALS AND METHODS

In this single-arm, phase II, multi-institutional study, 92 patients with biopsy-confirmed HCC or ICC, determined to be unresectable by multidisciplinary review, with a Child-Turcotte-Pugh score (CTP) of A or B, ECOG performance status of 0 to 2, no extrahepatic disease, and no prior radiation received 15 fractions of proton therapy to a maximum total dose of 67.5 Gy equivalent. Sample size was calculated to demonstrate > 80% local control (LC) defined by Response Evaluation Criteria in Solid Tumors (RECIST) 1.0 criteria at 2 years for HCC patients, with the parallel goal of obtaining acceptable precision for estimating outcomes for ICC.

RESULTS

Eighty-three patients were evaluable: 44 with HCC, 37 with ICC, and two with mixed HCC/ICC. The CTP score was A for 79.5% of patients and B for 15.7%; 4.8% of patients had no cirrhosis. Prior treatment had been given to 31.8% of HCC patients and 61.5% of ICC patients. The median maximum dimension was 5.0 cm (range, 1.9 to 12.0 cm) for HCC patients and 6.0 cm (range, 2.2 to 10.9 cm) for ICC patients. Multiple tumors were present in 27.3% of HCC patients and in 12.8% of ICC patients. Tumor vascular thrombosis was present in 29.5% of HCC patients and in 28.2% of ICC patients. The median dose delivered to both HCC and ICC patients was 58.0 Gy. With a median follow-up among survivors of 19.5 months, the LC rate at 2 years was 94.8% for HCC and 94.1% for ICC. The overall survival rate at 2 years was 63.2% for HCC and 46.5% ICC.

CONCLUSION

High-dose hypofractionated proton therapy demonstrated high LC rates for HCC and ICC safely, supporting ongoing phase III trials of radiation in HCC and ICC.

Gender-Specific Molecular and Clinical Features Underlie Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer that occurs more frequently in men, but is associated with longer survival in women. Insight into the survival advantage of female patients may advance the molecular understanding of MPM and identify therapeutic interventions that will improve the prognosis for all MPM patients. In this study, we performed whole-genome sequencing of tumor specimens from 10 MPM patients and matched control samples to identify potential driver mutations underlying MPM. We identified molecular differences associated with gender and histology. Specifically, single-nucleotide variants of BAP1 were observed in 21% of cases, with lower mutation rates observed in sarcomatoid MPM (P < 0.001). Chromosome 22q loss was more frequently associated with the epithelioid than that nonepitheliod histology (P = 0.037), whereas CDKN2A deletions occurred more frequently in nonepithelioid subtypes among men (P = 0.021) and were correlated with shorter overall survival for the entire cohort (P = 0.002) and for men (P = 0.012). Furthermore, women were more likely to harbor TP53 mutations (P = 0.004). Novel mutations were found in genes associated with the integrin-linked kinase pathway, including MYH9 and RHOA. Moreover, expression levels of BAP1, MYH9, and RHOA were significantly higher in nonepithelioid tumors, and were associated with significant reduction in survival of the entire cohort and across gender subgroups. Collectively, our findings indicate that diverse mechanisms highly related to gender and histology appear to drive MPM.