Therapy-Induced Senescence Contributes to the Efficacy of Abemaciclib in Patients with Dedifferentiated Liposarcoma

PURPOSE

We conducted research on CDK4/6 inhibitors (CDK4/6i) simultaneously in the preclinical and clinical spaces to gain a deeper understanding of how senescence influences tumor growth in humans.

PATIENTS AND METHODS

We coordinated a first-in-kind phase II clinical trial of the CDK4/6i abemaciclib for patients with progressive dedifferentiated liposarcoma (DDLS) with cellular studies interrogating the molecular basis of geroconversion.

RESULTS

Thirty patients with progressing DDLS enrolled and were treated with 200 mg of abemaciclib twice daily. The median progression-free survival was 33 weeks at the time of the data lock, with 23 of 30 progression-free at 12 weeks (76.7%, two-sided 95% CI, 57.7%-90.1%). No new safety signals were identified. Concurrent preclinical work in liposarcoma cell lines identified ANGPTL4 as a necessary late regulator of geroconversion, the pathway from reversible cell-cycle exit to a stably arrested inflammation-provoking senescent cell. Using this insight, we were able to identify patients in which abemaciclib induced tumor cell senescence. Senescence correlated with increased leukocyte infiltration, primarily CD4-positive cells, within a month of therapy. However, those individuals with both senescence and increased TILs were also more likely to acquire resistance later in therapy. These suggest that combining senolytics with abemaciclib in a subset of patients may improve the duration of response.

CONCLUSIONS

Abemaciclib was well tolerated and showed promising activity in DDLS. The discovery of ANGPTL4 as a late regulator of geroconversion helped to define how CDK4/6i-induced cellular senescence modulates the immune tumor microenvironment and contributes to both positive and negative clinical outcomes. See related commentary by Weiss et al., p. 649.

A Phase II Study of Epacadostat and Pembrolizumab in Patients with Advanced Sarcoma

PURPOSE

Epacadostat, an indole 2,3 dioxygenase 1 (IDO1) inhibitor, proposed to shift the tumor microenvironment toward an immune-stimulated state, showed early promise in melanoma but has not been studied in sarcoma. This study combined epacadostat with pembrolizumab, which has modest activity in select sarcoma subtypes.

PATIENTS AND METHODS

This phase II study enrolled patients with advanced sarcoma into five cohorts including (i) undifferentiated pleomorphic sarcoma (UPS)/myxofibrosarcoma, (ii) liposarcoma (LPS), (iii) leiomyosarcoma (LMS), (iv) vascular sarcoma, including angiosarcoma and epithelioid hemangioendothelioma (EHE), and (v) other subtypes. Patients received epacadostat 100 mg twice daily plus pembrolizumab at 200 mg/dose every 3 weeks. The primary endpoint was best objective response rate (ORR), defined as complete response (CR) and partial response (PR), at 24 weeks by RECIST v.1.1.

RESULTS

Thirty patients were enrolled [60% male; median age 54 years (range, 24-78)]. The best ORR at 24 weeks was 3.3% [PR, n = 1 (leiomyosarcoma); two-sided 95% CI, 0.1%-17.2%]. The median PFS was 7.6 weeks (two-sided 95% CI, 6.9-26.7). Treatment was well tolerated. Grade 3 treatment-related adverse events occurred in 23% (n = 7) of patients. In paired pre- and post-treatment tumor samples, no association was found between treatment and PD-L1 or IDO1 tumor expression or IDO-pathway-related gene expression by RNA sequencing. No significant changes in serum tryptophan or kynurenine levels were observed after baseline.

CONCLUSIONS

Combination epacadostat and pembrolizumab was well tolerated and showed limited antitumor activity in sarcoma. Correlative analyses suggested that inadequate IDO1 inhibition was achieved.

Randomized Phase II Trial of Sunitinib or Cediranib in Alveolar Soft Part Sarcoma

PURPOSE

Alveolar soft part sarcoma (ASPS) is a rare, highly vascular tumor with few treatment options. We designed a phase II randomized trial to determine the activity and tolerability of single-agent cediranib or sunitinib in patients with advanced metastatic ASPS.

PATIENTS AND METHODS

Patients 16 years of age and older were randomized to receive cediranib (30 mg) or sunitinib (37.5 mg) in 28-day cycles. Patients could cross over to the other treatment arm at disease progression. The primary endpoint was to measure the objective response rate (ORR) for each agent. Median progression-free survival (mPFS) for the two arms was also determined.

RESULTS

Twenty-nine of 34 enrolled patients were evaluable for response. One patient on each of the initial two treatment arms had a partial response (ORR: 6.7% and 7.1% for cediranib and sunitinib, respectively). Twenty-four patients had a best response of stable disease (86.7% and 78.6% for cediranib and sunitinib, respectively). There were no significant differences in mPFS for the two treatment arms. Clinical benefit (i.e., objective response or stable disease for a minimum of four or six cycles of therapy) on the first-line tyrosine kinase inhibitor (TKI) therapy did not predict benefit on the second-line TKI. Both drugs were well tolerated. As of August 2021, 1 patient (unevaluable for ORR) remains on study.

CONCLUSIONS

The study did not meet its endpoints for ORR. Although both TKIs provided clinical benefit, the outcomes may have been attenuated in patients who had progressed ≤6 months before enrollment, potentially accounting for the low response rates. See related commentary by Wilky and Maleddu, p. 1163.

Abstract PR012: Targeted sequencing of 2,138 bone and soft tissue sarcomas reveals commonly altered pathways, subtype-independent genetic clusters, and potential therapeutic targets

A hallmark of sarcomas is genetic, biologic, and clinical heterogeneity, which is a challenge for preclinical development of therapeutic targets, clinical trial design, and patient care. Because sarcomas comprise over 100 subtypes, a broad comparative genetic analysis of subtypes has been lacking and sarcoma genetic studies have by necessity focused on one or a few subtypes. We will report the results of a comprehensive analysis of somatic genetic alterations detected by a targeted sequencing platform in a single institution cohort of 2,138 patient-specific samples of soft tissue and bone sarcoma representing 45 distinct pathological entities. We determined subtype-specific mutation and copy number (arm and gene level) events with a focus on pathways in which there are therapeutic targets under clinical or preclinical investigation. The most commonly altered pathways are cell cycle control, TP53, PI3K, receptor tyrosine kinase/RAS, and epigenetic regulators (e.g. >40% of uterine leiomyosarcoma [n=165], undifferentiated pleomorphic sarcoma [UPS, n=145] and pleomorphic liposarcoma [n=22]). Subtype-specific associations in rare subtypes include TERT amplification in 41% of intimal sarcoma (n=18) and alterations in chromatin remodeling and histone modifying complexes in uterine adenosarcoma (43% and 36%, respectively; n=14). Epigenetic pathway alterations in common sarcomas were also noted, including an increased frequency of oncogenic alterations in epigenetic regulators in dedifferentiated liposarcoma (DDLS; n=167) (25%) vs. well differentiated liposarcoma (8%; n=48). We evaluated rates of whole genome doubling (WGD), which in subtypes such as UPS and osteosarcoma (n=129) were >45%, which is more frequent than many carcinomas. WGD associated with worse overall survival in metastatic (p=0.042) but not primary samples (p=0.391). Among specific subtypes, WGD was associated with worse overall survival in metastatic UPS (p=0.022). Unsupervised clustering of samples based on genetic features revealed that in some cases sarcomas are more similar to individual tumors of distinct histology than to other sarcomas of the same subtype. For example, UPS and soft tissue leiomyosarcoma (n=125) segregated into multiple genetic clusters (high entropy) compared to others with low entropy (DDLS), which could have implications for future clinical trial interpretation and/or design. We also determined the subtype-specific rate of tumor mutation burden, which was overall low compared to many carcinomas, but notably varied between and within subtypes, with some having a long tail in the upper range of the distribution. Lastly, we assessed targetable alterations on a subtype-specific basis. Together with other ‘multiomic’ approaches, we anticipate this work will motivate preclinical studies of subtype-specific sarcoma biology and potential therapeutic targets and will inform efforts to interpret outcomes in sarcoma clinical trials with respect to underlying genetic subtypes.

Citation Format: Benjamin A. Nacev, Francisco Sanchez-Vega, Shaleigh Smith, Cristina Antonescu, Evan Rosenbaum, Hongyu Shi, Cerise Tang, Nicholas Socci, Satshil Rana, Rodrigo Gularte-Merida, Ahmet Zehir, Mrinal Gounder, Timothy Bowler, Anisha Luthra, Bhumika Jadeja, Azusa Okada, Jonathan Strong, Jake Stoller, Jason Chan, Ping Chi, Sandra D'Angelo, Mark Dickson, Ciara Kelly, Mary Louise Keohan, Sujana Movva, Katherine Thornton, Paul Meyers, Leonard Wexler, Emily Slotkin, Julia Glade Bender, Neerav Shukla, Martee Hensley, John Healey, Michael La Quaglia, Kaled Alektiar, Aimee Crago, Sam Yoon, Brian Untch, Sarah Chiang, Narasimhan Agaram, Meera Hameed, Michael Berger, David Solit, Nikolaus Schultz, Marc Ladanyi, Samuel Singer, William Tap. Targeted sequencing of 2,138 bone and soft tissue sarcomas reveals commonly altered pathways, subtype-independent genetic clusters, and potential therapeutic targets [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr PR012.

Pilot study of bempegaldesleukin in combination with nivolumab in patients with metastatic sarcoma

PD-1 blockade (nivolumab) efficacy remains modest for metastatic sarcoma. In this paper, we present an open-label, non-randomized, non-comparative pilot study of bempegaldesleukin, a CD122-preferential interleukin-2 pathway agonist, with nivolumab in refractory sarcoma at Memorial Sloan Kettering/MD Anderson Cancer Centers (NCT03282344). We report on the primary outcome of objective response rate (ORR) and secondary endpoints of toxicity, clinical benefit, progression-free survival, overall survival, and durations of response/treatment. In 84 patients in 9 histotype cohorts, all patients experienced ≥1 adverse event and treatment-related adverse event; 1 death was possibly treatment-related. ORR was highest in angiosarcoma (3/8) and undifferentiated pleomorphic sarcoma (2/10), meeting predefined endpoints. Results of our exploratory investigation of predictive biomarkers show: CD8 + T cell infiltrates and PD-1 expression correlate with improved ORR; upregulation of immune-related pathways correlate with improved efficacy; Hedgehog pathway expression correlate with resistance. Exploration of this combination in selected sarcomas, and of Hedgehog signaling as a predictive biomarker, warrants further study in larger cohorts.

Abstract CT168: Randomized phase 2 trial of sunitinib or cediranib in alveolar soft part sarcoma

Background: Alveolar soft part sarcoma (ASPS) is a rare, highly vascular tumor with few effective treatment options. Cediranib (C) and sunitinib (S) are potent oral inhibitors of all 3 VEGF receptors. Cediranib showed substantial single-agent activity (objective response rate [ORR] = 35%) in our previous trial in patients (pts) with metastatic ASPS (NCT00942877). Here we report a phase 2 randomized multicenter trial of single agent C or S in pts with ASPS (NCT01391962).

Methods: We conducted a multicenter phase 2 trial with an optimal 2-stage design targeting an ORR of 40%. Enrolled pts were >16 years with metastatic ASPS, previously not treated (N) and unresectable, or previously treated (T), who have progressed per RECIST 1 within the 6-month period preceding enrollment. Pts were randomized to receive C (30 mg) or S (37.5 mg) orally, once a day, in 28-day cycles and could crossover to the other treatment arm at disease progression. ORR (primary endpoint), median progression-free survival (mPFS), and PFS rate at 24 weeks for the 2 arms (C and S) were evaluated; T and N cohorts were assessed separately in each arm. Arm accrual closed if ≤ 1 of the first 10 enrolled pts responded to the first treatment.

Results: Thirty-four pts (47% white, 29.4% black, 17.6% Asian, 5.8% Pacific Islander) were enrolled; 29 pts were evaluable for response. One pt on each of the initial treatment arms had a confirmed partial response (PR), rates of 6.7% (1/154) and 7.1% (1/14) for C and S tx or tx-naive, respectively. Among pts who crossed over, there was 1 PR in a pt receiving C after initially responding (PR) on S (1/9; ORR 11.1%). Twenty-four pts had a best response of stable disease (86.7% and 78.6%) for C and S, respectively. The mPFS was 7.6 months (mo) (95% CI: 3.7-9.9 mo) and 5.5 mo (95% CI: 1.8-14.5 mo) for C and S, respectively administered as first therapy (p=0.92). PFS rate at 24 weeks was 62.5% (95% CI: 29.5-76.2%) and 50% (95% CI: 25.9-70.1%) for pts receiving C and S respectively, as initial therapy. There was no difference in mPFS between T or N pts in the C (6.7 mo [95% CI: 1.4-9.9 mo] vs 8.3 mo [95% CI: 2.7 - 16.6 mo]; P=0.35) arm, but some evidence of a potential difference in the S (4.8 mo [95% CI: 0.9-7.9 mo] vs 14.7 mo 95% CI: 1.8 - 21.6 mo]; P=0.058) arm. Overall, 43.7% (C) and 77.8% (S) of pts experienced grade ≥3 adverse events (AEs) at least possibly related to the study drug. Common grade ≥3 AEs included: diarrhea (C), neutropenia (S), hypertension (C and S). AEs were in line with the known safety profiles of each agent. As of August 2021, 1 pt (unevaluable for ORR) remains on study.

Conclusions: The study did not meet its endpoints for ORR. There were no differences in mPFS for the 2 treatment arms. The selection of pts with more aggressive disease, who had progressed in the 6 months prior to enrollment, may account for the low patient response rates compared to our previous study of cediranib in ASPS.

Funded by NCI Contract No. HHSN261200800001E. The study was a collaboration between NCI and Pfizer.

Citation Format: Naoko Takebe, James Nguyen, Shivaani Kummar, Albiruni Abdul Razak, Sant P. Chawla, Suzanne George, Shreyaskumar R. Patel, Mary Louise Keohan, Sujana Movva, Geraldine O’Sullivan, Khanh Do, Larry Anderson, Lamin Juwara, Brooke Augustine, Seth Steinberg, Laura Kuhlmann, S. Percy Ivy, James H. Doroshow, Alice P. Chen. Randomized phase 2 trial of sunitinib or cediranib in alveolar soft part sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT168.

Clinical sequencing of soft tissue and bone sarcomas delineates diverse genomic landscapes and potential therapeutic targets

The genetic, biologic, and clinical heterogeneity of sarcomas poses a challenge for the identification of therapeutic targets, clinical research, and advancing patient care. Because there are > 100 sarcoma subtypes, in-depth genetic studies have focused on one or a few subtypes. Herein, we report a comparative genetic analysis of 2,138 sarcomas representing 45 pathological entities. This cohort is prospectively analyzed using targeted sequencing to characterize subtype-specific somatic alterations in targetable pathways, rates of whole genome doubling, mutational signatures, and subtype-agnostic genomic clusters. The most common alterations are in cell cycle control and TP53, receptor tyrosine kinases/PI3K/RAS, and epigenetic regulators. Subtype-specific associations include TERT amplification in intimal sarcoma and SWI/SNF alterations in uterine adenosarcoma. Tumor mutational burden, while low compared to other cancers, varies between and within subtypes. This resource will improve sarcoma models, motivate studies of subtype-specific alterations, and inform investigations of genetic factors and their correlations with treatment response.

A pilot study of lenvatinib plus pembrolizumab in patients with advanced sarcoma

TPS11588

Background: New treatment options are needed for sarcomas. Pazopanib is the only targeted agent approved for multiple soft tissue sarcoma (STS) subtypes with a response rate of 6% and a PFS of 4.6 months. Immunotherapy has a limited role in STS, as the SARC028 study of pembrolizumab demonstrated an overall response rate of 18%, with the highest response rate seen in the undifferentiated pleomorphic sarcoma (UPS) cohort at 23%. Lenvatinib is an oral, multi-tyrosine kinase inhibitor approved for the treatment of multiple cancer types including progressive, radioiodine-refractory thyroid cancer and unresectable hepatocellular carcinoma with inhibitory activity against the receptor tyrosine kinases VEGFR 1-3, FGFR 1-3, KIT, PDGFR alpha/beta, and RET. Early outcomes with the combination of lenvatinib and pembrolizumab suggest that this regimen could be broadly superior to PD-1 targeting alone for several tumor types as high rates of objective response have been noted. The rationale for this study is based on preclinical work demonstrating the immunosuppressive effects of VEGF in the tumor immune microenvironment including inhibition of dendritic cell maturation, recruitment of immunosuppressive Tregs, MDSCs and TAMs and up-regulation of PD-1 on CD8+ cells. Methods: This is a pilot study evaluating the efficacy of lenvatinib and pembrolizumab in the treatment of select metastatic and/or unresectable sarcomas. Patients will be enrolled in one of five cohorts: Cohort A: leiomyosarcoma; Cohort B: UPS; Cohort C: vascular sarcomas (including angiosarcoma and epithelioid hemangioendothelioma); Cohort D: synovial sarcoma and malignant peripheral nerve sheath tumor; and Cohort E: bone sarcomas (limited to osteosarcoma and chondrosarcoma). Eligible patients should have had at least one prior therapy for unresectable and/or metastatic disease, but no more than three prior lines of therapy. Prior treatment with angiogenesis inhibitors or immunotherapy is excluded. Archival tissue is required for eligibility. Patients enrolled in the study will be treated initially with a 2 week run-in of lenvatinib 20 mg orally daily which will be continued daily thereafter. Subsequently, they will start pembrolizumab 200 mg intravenously every 21 days. The primary endpoint for each cohort is best overall response rate documented by RECIST v1.1 Criteria at 27 weeks. A sample size of 10 patients is planned for each of the five histological cohorts. If 2 or more confirmed responses are observed among the 10 patients in an arm, the drug combination will be considered positive and worthy of further investigation for that arm. Secondary endpoints are PFS, OS, duration of response and safety/tolerability of the combination. On-treatment biopsy and blood samples will be required for correlative assessments. Accrual in all cohorts is ongoing. Clinical trial information: NCT04784247.

A phase I/II study of prexasertib in combination with irinotecan in patients with relapsed/refractory desmoplastic small round cell tumor and rhabdomyosarcoma

11503

Background: Prexasertib (PRX) is an inhibitor of CHK1, prevents DNA repair leading to mitotic catastrophe, and can enhance the activity of DNA-damaging chemotherapy. Translocation driven sarcomas exhibit high levels of replication stress and have demonstrated susceptibility to CHK1 inhibition in preclinical models. Desmoplastic small round cell tumor (DSRCT) and rhabdomyosarcoma (RMS) are aggressive sarcomas of children, adolescents and young adults for which novel therapies are urgently required. Methods: We conducted a phase I/II trial of PRX with irinotecan (irino) in patients ≥ 12 months of age with relapsed or refractory DSRCT or RMS. Eligible patients could have any number of prior therapies, including irino. Dose level 1 was PRX 80 mg/m2 on day 1 + irino 20 mg/m2 for 10 days. Dose levels 2 and 2A were PRX 105 or 150 mg/m2 (>21 years or ≤ 21 years) on day 1 and irino 20 mg/m2 for 10 (level 2) or 5 (level 2A) days. All cycles were 21 days. The primary objectives were to determine the RP2D of PRX with irino, and to determine the best overall response rate (ORR) in 6 months at the RP2D (RECIST v1.1) in DSRCT, with 3 or more responses out of 16 considered promising. Results: 21 patients were enrolled (DSRCT: 19; 2 RMS:2). The RP2D was dose level 2A. Treatment was well tolerated with the most common adverse events being neutropenia (48%), nausea (48%), and fatigue (52%). Cytopenias were managed with the aid of growth factor support in all patients once the RP2D was established. The DSRCT expansion enrolled 13 of 16 planned patients due to discontinuation of PRX supply prior to study completion. Four patients remain on therapy at the time of this submission. Responses in DSRCT patients at all dose levels are shown in Table. Sixteen of 21 enrolled patients, and 5 of 6 patients achieving PR had previously received irino. The median (range) number of cycles was 7 (2-26). Both RMS patients treated at the RP2D experienced SD as best response. The estimated ORR at the RP2D was 23%, and lower boundary of the one-sided 90% confidence interval was 9%, exceeding the unpromising rate of 5%. The two-sided 90% confidence interval was 7 to 49%. In addition, 3 patients had a PR at doses lower than the RP2D, bringing the ORR for all dose levels (n = 19) to 32% (90%CI: 15 to 53%). Conclusions: The RP2D of PRX in combination with irino is PRX 105 or 150 mg/m2 (>21 years or ≤ 21 years) on day 1 and irino 20 mg/m2 for 5 days in 21 day cycles with myelosuppression successfully managed with growth factor support. The study met its primary objective to consider PRX + irino promising in DSRCT and should be further investigated. Clinical trial information: NCT04095221. [Table: see text]

Presence of immune infiltrates, increased expression of transposable elements, and viral response pathways in sarcoma associate with response to checkpoint inhibition

11510

Background: Response to checkpoint inhibition (CPI) in sarcoma is overall low and varies between and within subtypes. Understanding tumor intrinsic determinants of this response may improve efficacy and patient selection. The de-repression of transposable elements (TEs), which are epigenetically silenced repetitive DNA elements of viral origin, is linked to anti-tumor immunity through an antiviral inflammatory response. We hypothesize that baseline expression of TEs and epigenetic regulators correlates with overall response rate (ORR) in sarcoma CPI clinical trials. Methods: This is a retrospective analysis of bulk RNA-sequencing data from pre-treatment biopsies of patients on CPI trials in sarcoma (pembrolizumab plus talimogene laherparepvec, nivolumab plus bempegaldesleukin, and pembrolizumab plus epacadostat). Sixty-seven samples from unique patients representing 12 subtypes were analyzed. The MCP counter deconvolution method and unsupervised clustering were used to group samples by immune phenotypes resulting in immune ‘hot’ and ‘cold’ clusters. ORR was defined by RECIST. To determine if baseline expression of TEs and epigenetic regulators significantly predicted immune types, we implemented a lasso penalized logistic regression. Results: Immune ‘hot’ tumors were characterized by increased immune infiltrates including CD8+ T-cells, B-cells, and NK cells vs ‘cold’ tumors. Patients with ‘hot’ vs ‘cold’ tumors had an ORR of 30.5% (11/36) vs. 3.2% (1/31) (p = 0.003; chi-squared). The best predictors of ‘hot vs ‘cold’ was the increased expression of multiple TE families including MER45A, MER57F, and LTR21B (respective lasso coefficients, 0.27, 0.07, and 0.07). Expression of IKZF1, a chromatin-interacting transcription factor, was also predictive (lasso coefficient, 0.35) and increased expression correlated with improved ORR (p = 0.003; unpaired t-test). TE and IKFZ1 expression was significantly correlated with CD8+ T-cell signaling and antiviral response pathways such as cGAS-STING (MER57F, r2= 0.43, padj = 1.75E-4; IKZF1, r2= 0.63, padj = 6.28E-9) and type II interferon (MER57F, r2= 0.67, padj = 2.51E-10; IKZF1, r2= 0.60, padj = 7.19E-8). Increased expression of cGAS-STING (p = 3.9E-4; unpaired t-test) and type II interferon pathways (p = 1.89E-10; unpaired t-test) was significant in ‘hot’ tumors. Conclusions: Immune ‘hot’ baseline immune profiles of sarcoma are associated with improved ORR to CPI and with increased expression of TEs and IKZF1. These differences in gene expression correlate with increased inflammatory signaling, which suggests a response to TE-encoded viral-like sequences that are typically epigenetically silenced. Induction of TE de-repression and IKZF1 expression through epigenetic targeting warrants pre-clinical investigation as a strategy to promote CPI response in sarcomas.

A phase I/II trial of the PD-1 inhibitor retifanlimab (R) in combination with gemcitabine and docetaxel (GD) as first-line therapy in patients (Pts) with advanced soft-tissue sarcoma (STS)

11516

Background: In a phase III trial, GD had similar response and survival rates to doxorubicin when administered as first-line therapy to advanced STS pts. G and D have each demonstrated synergy with PD-1 blockade in pre-clinical or clinical studies. We hypothesized that GD plus R would be safe, tolerable, and have synergistic activity in STS. Methods: This is an ongoing open-label, single-center, phase I/II trial of R (INCMGA00012) combined with GD in pts with treatment-naïve unresectable or metastatic high-grade STS. Herein, we report the phase I results, which included a safety run-in followed by a 3+3 dose de-escalation design. G (900 mg/m2) was administered on days 1 and 8 and D (75 mg/m2) on day 8, in 21-day cycles. R (210 mg IV flat dose on the run-in portion and 375 mg on the dose de-escalation portion) was administered on day 1 of each cycle starting in cycle 2 and continued as monotherapy after completion of 6 cycles of GD. The primary endpoint of the phase I was to determine the recommended phase 2 dose (RP2D) of R plus GD. Secondary endpoints included describing the safety, assessing best overall response rate (ORR) by RECIST 1.1, disease control rate (DCR), and progression-free survival (PFS). Results: Thirteen pts were treated, 7on the run-in and 6 on the de-escalation portion. One pt progressed prior to starting R and was replaced. Median pt age was 53 (range 28 – 74) and 7 were female. Histologies included leiomyosarcoma (n = 6), undifferentiated pleomorphic sarcoma (2), dedifferentiated liposarcoma (2), pleomorphic liposarcoma (1), angiosarcoma (1), and myxofibrosarcoma (1). The Table lists treatment-related adverse events (TRAEs) that occurred in ≥ 20% pts in descending order of frequency. Additional Grade (Gr) 3 TRAEs occurring in 1 pt each, included: infusion reaction, leukopenia, anorectal infection, neutropenia, and pyelonephritis. Gr 3 pyelonephritis was the only dose-limiting toxicity. There were no Gr ≥ 4 TRAEs. One pt (Gr 3 elevated AST/ALT) required corticosteroids and cessation of study therapy. The RP2D was determined to be 375 mg of R plus GD. Twelve pts were evaluable for response. ORR was 17% (1 of 6; 95% CI 1 - 64%) and 50% (3 of 6; 95% CI 19% - 81%) in the run-in and de-escalation cohorts, respectively. DCR was 100% (6 of 6; 95% CI 52 - 100%) and 83% (5 of 6; 95% CI: 36 - 99%). PFS rates at 24 weeks were 60% (95% CI: 29 - 100%) and 44% (95% CI: 17 - 100%). Conclusions: R plus GD was generally safe and well tolerated with no unexpected safety signals to date. The phase II portion evaluating efficacy of R plus GD at the RP2D is ongoing. Clinical trial information: NCT04577014. [Table: see text]

Long term follow-up and patterns of response, progression and hyperprogression in patients after PD-1 blockade in advanced sarcoma

PURPOSE

PD-1 blockade can mediate objective responses in advanced sarcomas, but their durability has not been established and it is unclear if hyperprogressive disease (HPD) occurs in sarcomas treated with PD-1 inhibitors.

METHODS

We pooled patients who were treated prospectively with nivolumab or pembrolizumab as monotherapy or with bempegaldesleukin, epacadostat, ipilimumab or Talimogene laherparepvec. We did a new independent assessment for HPD and analyzed clinical, pathologic and genomic data from baseline tumor biopsies. Our primary endpoint was the incidence of HPD; secondary endpoints were clinical or genomic correlates of response or HPD.

RESULTS

We treated 134 patients with advanced sarcoma from 2015 - 2019. Twenty-one patients (16%) had a complete or partial response (CR/PR), and 30% of responses were durable for over 2 years. Forty-eight (36%) patients had stable disease (SD), 45 (34%) had progressive disease without HPD (PD) and 15 (11%) had HPD. Five patients (4%) were not evaluable for HPD. The sarcoma subtypes, sites of metastasis, clinical course, and genomic alterations in patients with PD and HPD were similar, except HPD tumors were smaller at baseline.

CONCLUSIONS

In patients with advanced sarcoma, PD-1 blockade can mediate durable responses. HPD occurs in sarcoma at an incidence that is similar to what has been reported in other solid tumors, but patients with HPD were clinically and biologically similar to those who had PD. Further research is required to establish whether HPD is a biologically distinct phenomenon and whether a theoretical risk of HPD should influence patient management.

A phase 1b study of avelumab plus DCC-3014, a potent and selective inhibitor of colony stimulating factor 1 receptor (CSF1R), in patients with advanced high-grade sarcoma

11549

Background: Select sarcomas are infiltrated with immunosuppressive myeloid cells. DCC-3014 is an inhibitor of the CSF1R kinase that decreases tumor infiltrating myeloid cells in preclinical models. We hypothesized that DCC-3014 combined with the anti-PDL1 inhibitor avelumab would be safe and tolerable, decrease immunosuppressive myeloid cells, and increase cytotoxic T cells. Methods: This investigator initiated, open label, single center, phase I study of DCC-3014 plus avelumab in patients (pts) with unresectable or metastatic sarcoma utilized a standard 3+3 dose escalation design. DCC-3014 was administered on days 1-3 (loading dose of 20, 30, or 50 mg) followed by oral daily maintenance (10, 14, or 20 mg) in 28-day cycles; 800 mg of IV avelumab was administered q2weeks. The primary endpoint was to determine the recommended phase 2 dose (RP2D). Secondary endpoints defined the adverse event (AE) profile and assessed clinical efficacy. Peripheral blood CD14+Lin-HLA-DRlo myeloid-derived suppressor cells (MDSCs) were measured by flow cytometry. Results: 13 pts were treated; median age was 61 (range 32 – 71), 8 were female, and median prior lines of therapy was 5 (range 2 – 10). Histologic subtypes included leiomyosarcoma (LMS, n = 7), undifferentiated pleomorphic sarcoma (2), dedifferentiated liposarcoma (LPS, 2), synovial sarcoma (1), and pleomorphic LPS (1). The Table lists treatment-related AEs (TRAEs) of any grade (G) occurring in ≥ 10% of pts and all G ≥ 3 TRAEs, sorted by frequency. All pts had at least 1 TRAE. Seven pts (54%) had a G ≥ 3 TRAE. Most TRAEs were either G ≤ 2 or expected on-target effects of CSF1R inhibition. 1 of 6 pts on the highest dose level had a dose limiting toxicity (G4 elevated AST with abdominal pain) that resolved with treatment cessation. The highest dose level was declared the RP2D. Best objective response by RECIST 1.1 was stable disease in 3 pts; 2 had LMS and were treated at the highest dose level. At baseline, the mean proportion of monocytes in peripheral blood samples with an MDSC phenotype was 12.2% (range 7.1 – 19.9). 5 of 7 pts with serial blood samples had decreased circulating MDSCs (mean decrease of 26.9% from baseline to last time point). Conclusions: DCC-3014 combined with avelumab was safe and tolerable. Study therapy decreased circulating MDSCs in select patients; T cell analyses will be reported. Study expansion at the RP2D is ongoing. Clinical trial information: NCT04242238. [Table: see text]

Objective Response Rate Among Patients With Locally Advanced or Metastatic Sarcoma Treated With Talimogene Laherparepvec in Combination With Pembrolizumab: A Phase 2 Clinical Trial

Importance

Patients with advanced sarcoma have limited treatment options. Talimogene laherparepvec (T-VEC) has been shown to increase tumor-specific immune activation via augmenting antigen presentation and T-cell priming.

Objective

To examine whether T-VEC in combination with pembrolizumab is associated with increased tumor-infiltrating lymphocyte infiltration and programmed death-ligand 1 expression and thus with increased antitumor activity in patients with locally advanced or metastatic sarcoma.

Design, Setting, and Participants

This open-label, single-institution phase 2 interventional trial of T-VEC plus pembrolizumab enrolled 20 patients with locally advanced or metastatic sarcoma between March 16 and December 4, 2017, for whom at least 1 standard systemic therapy had failed. The median duration of therapy was 16 weeks (range, 7-67 weeks). Reported analyses include data through December 14, 2018.

Intervention

Patients received pembrolizumab (200-mg flat dose) intravenously and T-VEC (first dose, ≤4 mL × 106 plaque-forming units [PFU]/mL; second and subsequent doses, ≤4 mL × 108 PFU/mL) injected into palpable tumor site(s) on day 1 of each 21-day cycle.

Main Outcomes and Measures

The primary end point was objective response rate (ORR; complete response and partial response) at 24 weeks determined by Response Evaluation Criteria In Solid Tumors (RECIST), version 1.1, criteria. Secondary end points included best ORR by immune-related RECIST criteria, progression-free survival rate at 24 weeks, overall survival, and safety.

Results

All 20 patients (12 women [60%]; median age, 63.5 years [range, 24-90 years]) were evaluable for response. The study met its primary end point of evaluating the best ORR at 24 weeks determined by RECIST, version 1.1, criteria; the best ORR was 30% (95% CI, 12%-54%; n = 6). The ORR overall was 35% (95% CI, 15%-59%; n = 7). The incidence of grade 3 treatment-related adverse events was low (4 patients [20%]). There were no grade 4 treatment-related adverse events or treatment-related deaths.

Conclusions and Relevance

In this phase 2 clinical trial, treatment with T-VEC plus pembrolizumab was associated with antitumor activity in advanced sarcoma across a range of sarcoma histologic subtypes, with a manageable safety profile. This combination therapy met its predefined primary study end point; further evaluation of T-VEC in combination with pembrolizumab for patients with select sarcoma subtypes is planned.

Trial Registration

ClinicalTrials.gov identifier: NCT03069378.

Association of immune-related adverse events (irAEs) with improved clinical outcome in sarcoma patients treated with immune checkpoint blockade (ICB)

11510

Background: IrAEs are associated with improved clinical outcomes after treatment with ICB in select epithelial malignancies. We hypothesized that sarcoma patients (pts) treated with ICB who developed an irAE would have improved outcomes compared to pts who had no irAE. Methods: Adverse events (AEs) from 3 sarcoma-specific ICB trials (nivolumab plus NKTR-214, pembrolizumab plus epacadostat, and pembrolizumab plus T-VEC) were reviewed. AEs probably or definitely related to ICB were classified as immune- or non-immune-related by the principal investigator. Endpoints of interest included best overall response (BOR) by RECIST 1.1 (complete response [CR]/partial response [PR]), durable clinical benefit (DCB; CR/PR/stable disease [SD] ≥ 16 weeks), and progression-free survival (PFS). Outcomes were stratified by the presence or absence of ≥ 1 irAE of any grade and by grade 1-2, grade 3-4, or no irAE (three-category comparison). Results: A total of 124 pts received ICB on these studies. Median pt age was 56 (range: 13-90); 53% were male; all but one pt had a performance status of ≤ 1. BOR was PR in 12 pts, SD in 41, and PD in 69. 2 pts were not evaluable. 40 pts (32%) had ≥ 1 irAE of any grade, 6 of whom had a grade 3-4 irAE. The most common irAEs (≥ 5% of pts) were rash (15%), arthralgia (11%), myalgia (9%), pruritis (8%), and hypothyroidism (6%). The proportion of pts with a CR/PR was higher in pts with than without an irAE (18% vs. 6%, respectively; P = 0.058). A significantly higher proportion of pts with an irAE had DCB compared to those without (53% and 29%, respectively; P = 0.017). The median PFS of pts with an irAE was 16.6 months compared to 10.6 in those without (P = 0.013). The proportion of pts with a grade 3-4 irAE and a CR/PR was highest (33%) compared to pts with grade 1-2 (15%) or no irAE (6%) (P = 0.048). More pts with grade 3-4 irAE achieved DCB (67%) than grade 1-2 (50%) or no irAE (29%) (P = 0.027). Median PFS was 22.6, 15, and 10.6 weeks in the grade 3-4, grade 1-2, and no irAE groups, respectively (P = 0.047). Conclusions: Approximately one-third of advanced sarcoma pts with ICB-based immunotherapy developed an irAE. As reported previously in select carcinomas, sarcoma pts with irAEs were more likely to have clinical benefit than those without irAEs. Further research is needed to understand the mechanism behind this association and to validate these findings prospectively.

HLA genotyping in synovial sarcoma: Identifying HLA-A*02 and its association with clinical outcome

e23560

Background: Patients (pts) with synovial sarcoma (SS) and an HLA-A*02 genotype whose tumors express NY-ESO-1 may be eligible for clinical trials of adoptive T cell therapy. We reasoned that a next generation tumor sequencing platform utilizing matched normal DNA (MSK-IMPACT) could accurately identify HLA genotype. Although HLA-A*02 is necessary for some adoptive T cell therapies, the prognosis of this genotype on clinical outcome has not been described in SS. Methods: Pts with metastatic SS who consented to screen for a clinical trial of engineered T cells had high-resolution HLA genotyping performed with a Clinical Laboratory Improvement Amendments (CLIA)-certified test. Where feasible, HLA genotype and loss-of-heterozygosity (LOH) of HLA alleles were determined from IMPACT samples. Overall survival (OS) was estimated in three overlapping cohorts and stratified by HLA-A*02 status: pts treated with anthracyclines or alkylators in the first line, pazopanib in the second line or beyond, and all pts from time of metastasis. Results: 66 pts with SS were screened, but not treated with T cells; 30% (n = 20) were HLA-A*02-positive on a CLIA-certified outside test. 23 pts had HLA genotyping both by IMPACT and an outside laboratory, 22 (96%) of whom had concordant results. 3 pts had LOH of at least 1 HLA allele, including one with LOH of HLA*02:01 in the primary tumor. Among pts treated chemotherapy (n = 36) or pazopanib (n = 37), OS did not significantly differ between HLA-A*02-positive or negative pts. Univariable analyses of OS from the time of metastasis in the whole cohort identified primary tumor size and time to metastasis as variables significantly associated with outcome (hazard ratio (HR) 1.2, 95% confidence interval (CI) 1.123 – 1.345 [P < 0.001] and HR 0.99, 95% CI 0.976 – 0.999 [P = 0.032], respectively). HLA-A*02-positive status and age did not reach the significance threshold (HR 1.95, 95% CI 0.995 – 3.813 [P = 0.052] and HR 1.021, 95% CI 0.999 – 1.044 [P = 0.061], respectively). Multivariable analysis found older age and larger tumor size were independently associated with significantly shorter OS (HR 1.03, 95% CI 1.002 – 1.049 [P = 0.037] and HR 1.2, 95% CI 1.127 – 1.37 [P < 0.001], respectively). Conclusions: Targeted exome panels like IMPACT that utilize matched tumor-normal DNA may accurately identify HLA genotype. Detection of LOH at HLA loci may identify a subgroup of pts who would be refractory to treatment with HLA-A*02-restricted engineered T cells. HLA-A*02 status was not associated with a statistically significant survival difference in pts with metastatic SS.

A phase II study of MEK162 (binimetinib [BINI]) in combination with imatinib in patients with untreated advanced gastrointestinal stromal tumor (GIST)

11508

Background: ETV1 and KIT are lineage-specific master transcriptional and signaling survival factors in GIST. In preclinical models, dual lineage targeting of ETV1 by MEK inhibition with BINI and KIT by imatinib are synergistic in suppressing GIST tumorigenesis and progression. This single-arm phase II study is designed to test the efficacy of the BINI+imatinib as a first-line treatment in patients (pts) with advanced GIST. Methods: Adult pts with untreated advanced GIST received imatinib (400mg daily) plus BINI (30mg twice daily), 28-day cycles. The primary endpoint (EP) was RECIST1.1 objective response rate (ORR) (complete response [CR]+partial response [PR]). The study was designed to detect a 20% improvement in the ORR of imatinib alone (unacceptable rate of 45%; acceptable rate of 65%). A sample size of 44 patients was required, using an exact binomial test, one-sided type I error of 0.08 and type II error of 0.1. Confirmed PR in > 24 pts would be considered positive. Secondary EPs included RR by Choi and EORTC criteria, resectability conversion rate (RCR), progression free survival (PFS), overall survival (OS) and long-term AEs. Correlatives included characterization of tumor genomics by MSK-IMPACT, cfDNA by MSK-ACCESS, ETV1 protein levels and transcriptomes and signaling inhibition. Results: At data cutoff of Jan 31, 2020, 38/39 pts with advanced GIST of all genotypes, including 3 KIT/PDGFRA-wild type GIST pts, were evaluable for primary EP. Median age 60 (range 29-78), 29% female. 26/38 pts with confirmed PR; Best ORR was 68.4% (two-sided 95% CI, 51-83%; one-sided 90% CI, 57-100%). 8/9 pts became resectable after treatment; RCR was 88.9% (95% CI, 52-100%). 13 pts remain on trial (2-159 weeks [wks]). 9 pts discontinued trial due to disease progression (11-159 wks); one pt progressed within 3 months, indicating primary resistance. Grade 3/4 toxicity included CPK elevation (asymptomatic, 61%), neutrophil decrease (11%), maculopapular rash (8%), anemia (8%). No unexpected toxicities observed. Correlation of outcome with MSK-IMPACT, MSK-Access and paired tumor biopsies will be presented. Conclusions: This study met its primary endpoint. BINI plus imatinib is highly effective in treatment-naive advanced GIST, with expected and manageable long-term treatment-associated toxicities. The combination strategy warrants further evaluation in direct comparison with imatinib in the frontline treatment of GIST. Clinical trial information: NCT01991379 .

Pilot study of NKTR214 and nivolumab in patients with sarcomas

11010

Background: Monotherapy checkpoint inhibitors have minimal efficacy in most patients with metastatic sarcoma. NKTR-214 is a CD122-preferential IL-2 pathway agonist that activates and expands natural killer and CD8+ T cells. Phase I/II data demonstrated the safety and efficacy of nivolumab plus NKTR-214 in multiple tumor types. A trial of NKTR-214 plus nivolumab was initiated in patients with selected sarcomas. Methods: This is a multi-center pilot study enrolling patients (pts) failing prior regimens within 9 cohorts: leiomyosarcoma (LMS), undifferentiated pleomorphic sarcoma (UPS), dedifferentiated liposarcoma (DDLPS), chondrosarcoma (CS), osteosarcoma (OS), angiosarcoma (AS), alveolar soft part sarcoma (ASPS), synovial sarcoma/small blue round cell and other. Pts received NKTR 0.006mg/kg with nivolumab 360 mg every 3 weeks. Primary endpoint was objective response rate (ORR), secondary endpoints were adverse events (AEs), progression-free, overall survival (PFS,OS) and clinical benefit rate (CBR.) Pre/on treatment biopsies performed on patients for correlative studies including PD-L1 expression and TIL characterization by immunohistochemistry, whole exome sequencing and RNAseq. Results: Enrollment completed with 10 patients in cohorts below. 50 pts enrolled (median age 58, range 14-80), 54% female. Median follow-up time is 13m. 50% of patients were refractory ≥3 lines of therapy. Grade 3/4 treatment related adverse events occurred in 26% of patients. 2% of patients stopped due to AEs. Median time to response was 3.6m. Responses seen in LMS, UPS, dedifferentiated CS; on-going in UPS/CS. Prolonged disease stability in DDLPS. 6 patients remain on treatment. Conclusions: Nivolumab plus NKTR-214 was safe and tolerable in heavily pre-treated and refractory sarcoma patients. Responses were protracted overtime; on-going in UPS and dedifferentiated CS. Prolonged disease stability seen in DDLPS in patients. All correlative analyses are in progress and will be presented. Enrollment continues with plans to add a treatment naïve cohort. Clinical trial information: NCT03282344. [Table: see text]

DNA damage response pathway alterations and clinical outcome in leiomyosarcoma

11048

Background: Leiomyosarcoma (LMS) is a complex karyotype sarcoma with frequent alterations in the homologous recombination (HR) pathway. Genomically unstable tumors with DNA damage repair (DDR) deficiencies may have improved responses to DNA damaging therapies, such as cytotoxic chemotherapy or PARP inhibitors. Methods: We retrospectively reviewed LMS patients treated at MSKCC who had targeted somatic DNA sequencing (MSK-IMPACT) performed on tumor tissue. 33 DDR genes, including 16 HR genes, were analyzed for oncogenic alterations. A composite HR deficiency (HRD) score measured tumor genomic scarring for each patient. To determine if DDR alteration status is prognostic of outcome, we analyzed the recurrence-free survival (RFS) of patients who underwent complete resection, and the overall survival (OS) of the whole cohort. Results: 211 patients had IMPACT testing between March 2014 and October 2018; 48% of samples were primary tumors and 52% recurrent/metastatic sites. Among soft tissue LMS (stLMS), there were 35 men and 55 women. 20% of patients had an oncogenic DDR gene alteration, 72% of which were in the HR pathway (table below). Uterine LMS (uLMS) had more DDR alterations than stLMS, though not statistically significant (p = 0.084). BRCA2 (n = 14 cases), RAD51B (8), and ERCC5 (4) were most frequently altered. HRD score significantly correlated with HRD alteration status (p = 0.004). DDR or HRD altered status and HRD score were associated with shorter RFS in patients with resectable disease, independent of age (p < 0.05). Median OS for the cohort was 75 months (95% CI: 64 – 84). Men with stLMS had shorter OS compared to women (p = 0.025). OS did not significantly differ based on DDR or HRD status (p > 0.05). Conclusions: One-fifth of LMS patients have one or more oncogenic somatic alterations in the DDR pathway, predominantly in effectors of HR. DDR status may be prognostic of recurrence risk. Further analyses to determine the association between DDR status and response to cytotoxic chemotherapy are ongoing. [Table: see text]

Phase 2 study of the CDK4 inhibitor abemaciclib in dedifferentiated liposarcoma

11004

Background: The oncogene cyclin-dependent kinase 4 (CDK4) is amplified in > 90% of de-differentiated liposarcomas (DDLS). We previously demonstrated that treatment with the CDK4 inhibitor palbociclib results in favorable progression-free survival (PFS) in DDLS. Abemaciclib is a newer and more potent CDK4 inhibitor. This single-arm phase 2 study was designed to test the activity of abemaciclib in DDLS. Methods: Participants were adults with advanced DDLS, measurable disease by RECIST 1.1, any (or no) priory therapy, and progression by RECIST in the 6 months prior to study entry. The primary endpoint was PFS at 12 weeks. Based on historical data, promising drugs have 12-week PFS of ≥ 40% and not promising ≤ 20%. This study would be positive if 12-week PFS was ≥ 60%. The study was approved by the Institutional Review Board of Memorial Sloan-Kettering Cancer Center and all patients provided written informed consent. The study was registered at Clinicaltrials.gov (NCT02846987) and study drug was provided by Eli-Lilly. Results: Treatment was abemaciclib 200 mg by mouth twice daily continuously. 30 patients were treated and 29 were evaluable for the primary endpoint. Patient characteristics: Median age 62 (range 39-88), 60% male. Lines of prior therapy: 0 (50%); 1 (33%); ≥ 2 (17%). The observed PFS at 12 weeks was 76% (95% CI 57-90%). Median PFS was 30.4 weeks (95% CI 28.9-NE). There was one partial response. A further 3 patients had > 10% decrease in tumor size by RECIST but did not meet the criterion for partial response. Grade 3-4 toxicity included anemia (37%), neutropenia (20%), thrombocytopenia (17%) and diarrhea (7%). Conclusions: This study met its primary endpoint. In patients with advanced progressive DDLS, abemaciclib treatment results in favorable PFS and objective tumor response with manageable toxicity. Updated response data and results of paired tumor biopsies will be presented. Clinical trial information: NCT02846987.

Sequenced circulating tumor (ct) DNA to detect the molecular landscape in advanced GIST

11036

Background: Molecular (mol) characteristics-guided precision therapy has well-established utility in GIST management. The GIST mol landscape is poorly represented by selective tumor biopsy (bx) material, especially in metastatic and treatment-refractory GIST. ctDNA can overcome some of the limitations of selective tissue bx specimens and provide comparable or greater mol information. ctDNA represents an emerging mol biomarker in advanced (adv) GIST. Methods: Next generation sequencing analyses (MSK-IMPACT or custom-capture GIST specific panel) were performed on ctDNA prospectively collected from patients (pts) with adv GIST. MSK-IMPACT was performed on tumor material (archival tissue or paired tissue bx specimens taken in parallel with ctDNA collection from clinical trial participants). The primary objective was to determine the concordance between the mol landscape of GIST identified by sequenced tumor tissue versus ctDNA. Secondary objective was to correlate characteristics of sequenced ctDNA with standard measurements of response assessment. Results: 47 ctDNA samples collected from 25 pts with adv GIST were sequenced using MSK-IMPACT ( > 400 genes). MSK-IMPACT was performed on archival tumor material. Sequenced ctDNA detected the mutational spectrum of tumor tissue in 48% of cases. In 50% of these cases, ctDNA identified novel treatment-resistance mutations not previously identified in the archival tissues. To optimize sensitivity of detection, a custom-designed GIST specific ctDNA sequencing panel was developed incorporating 19 of the most commonly altered genes observed from MSK-IMPACT analysis performed on > 75 imatinib-refractory adv GIST tumor samples. 52 ctDNA samples collected from 30 pts with paired tumor bx samples have been sequenced using the custom-capture GIST panel. The tumor bx samples have been sequenced using MSK-IMPACT. Results are pending and will be presented. A separate cohort of ctDNA samples serially collected in the setting of a prospective clinical trial are being sequenced. The mol results with correlated treatment response by RECIST will also be presented. Conclusions: ctDNA could detect a broad spectrum of mol heterogeneity and potentially be used as a biomarker to guide precision therapy in adv GIST. Further research is necessary to determine the optimal ctDNA sequencing assay and the appropriate clinical setting to utilize in GIST.

A phase II study of epacadostat and pembrolizumab in patients with advanced sarcoma

11049

Background: Tumors express IDO1, an intracellular enzyme involved in the degradation of tryptophan to kynurenine, in order to evade immunosurveillance. Epacadostat inhibits IDO1 and shifts the tumor microenvironment from an immunosuppressive state to an immune-stimulated state. Pembrolizumab previously demonstrated activity in select sarcoma subtypes. We performed an open-label, single-center, phase II study of epacadostat and pembrolizumab in patients with advanced sarcoma. Methods: Patients received the recommended phase II dose of oral epacadostat (100mg) twice per day and intravenous pembrolizumab (200mg/dose) every 3 weeks. The primary endpoint was best objective response rate (ORR) (complete response and partial response [PR]) at 24 weeks by RECIST 1.1. Secondary endpoints included adverse events (AEs), ORR by irRECIST, progression free survival (PFS) and overall survival (OS). Correlative studies performed on pre/on-treatment biopsy specimens included PD-L1, IDO1, and kynurenine expression and characterization of tumor infiltrating lymphocytes by IHC, whole exome and RNA sequencing. Results: Twenty-nine patients were enrolled [median age 53 years (range, 24-78), 57% male, ECOG PS 0 83%]. Histological subtypes included leiomyosarcoma (17%), UPS (17%), myxofibrosarcoma (7%), liposarcoma (10.5%), EHE (10.5%), angiosarcoma (3%), “other” sarcoma subtype (35%). Patients were refractory to 0 (21%), 1 (38%), 2 (24%) and ≥ 3 (17%) prior lines of therapy. The most common ( > 20% of pts) grade (G)1 or 2 treatment related AEs (TRAEs) observed included fatigue (31%), rash (31%) and ALT elevation (24%). G3 TRAEs included AST elevation (10%), ALT elevation, anemia, hypophosphatemia and increased lipase each occurred in 3% of pts. Three patients discontinued therapy due to G3 immune mediated hepatitis. Among the 29 evaluable patients 1 (3%) confirmed PR (leiomyosarcoma), 13 stable diseases (45%) and 15 progressions (52%) were observed by RECIST 1.1. The median PFS was 8.0 weeks (two-sided 95% CI: 6.9 ~ 26.7) and the PFS rate at 24 weeks was 27.9% (two-sided 95% CI: 15.0% ~ 52.2%). The median OS was not estimable (two-sided 95% CI: 40.9 weeks ~ NE). The OS at 24 weeks was 85.2% (95% CI: 72.8%, 99.7%). Conclusions: Epacadostat in combination with pembrolizumab was generally well tolerated. Limited anti-tumor activity was observed among advanced sarcoma patients. Correlative analyses including determination of adequacy of IDO1 inhibition will be reported. Clinical trial information: NCT03414229.

Complete metabolic response to therapy of hepatic epithelioid hemangioendothelioma evaluated with 18F-fluorodeoxyglucose positron emission tomography/contrast-enhanced computed tomography: A CARE case report

RATIONALE

Hepatic epithelioid hemangioendothelioma (EHE) is a rare malignant vascular tumor of endothelial origin with a highly variable clinical presentation and natural history. Given its vascular origin, new therapies with inhibitors of vascular endothelial growth factor (VEGF) have been introduced in the treatment of these patients and have shown promising results. Few reports have described the role of F-Fluorodeoxyglucose positron emission tomography/contrast-enhanced computed tomography (F-FDG PET/CT) in the evaluation of this tumor after treatment with anti-angiogenic agents. Our case reports how F-FDG PET-CT scan was critical in the assessment of this tumor after treatment with an anti-angiogenic agent, Pazopanib, demonstrating complete metabolic response.

PATIENT CONCERNS

A 30-year-old man with no previous significant medical history presented with pain in the right upper quadrant for over a year.

DIAGNOSES

Multiple hepatic masses were found on abdominal ultrasound. Liver biopsy confirmed the diagnosis of epithelioid hemangioendothelioma. F-FDG PET/CT was performed for staging. Multiple FDG-avid hepatic, splenic, and lymph nodes lesions were detected on F-FDG PET/CT. A subsequent spleen biopsy confirmed splenic involvement. Immunohistochemistry was positive for CD31, CD34, and ERG, supporting the diagnosis of epithelioid hemangioendothelioma.

INTERVENTIONS

A 1-year cyclophosphamide treatment was provided followed by Pazopanib for 17 months.

OUTCOMES

Six years after the first F-FDG PET/CT, F-FDG PET/CT performed for restaging demonstrated complete metabolic response to therapy. Follow-up CT demonstrated no interval changes in size of some of the treated lesions.

LESSON

F-FDG PET/CT is useful for baseline assessment and posttreatment follow-up of this rare cancer.

Progression-Free Survival Among Patients With Well-Differentiated or Dedifferentiated Liposarcoma Treated With CDK4 Inhibitor Palbociclib: A Phase 2 Clinical Trial

IMPORTANCE

More than 90% of well-differentiated or dedifferentiated liposarcomas (WD/DDLS) have CDK4 amplification. The selective CDK4 and CDK6 inhibitor palbociclib inhibits growth and induces senescence in liposarcoma cell lines and xenografts. Our prior phase 2 study demonstrated that treatment with palbociclib (200 mg daily for 14 days every 21 days) resulted in clinical benefit in WD/DDLS but moderate hematologic toxic effects. It is important to understand whether palbociclib at a new dose and schedule-125 mg daily for 21 days every 28 days-results in clinical benefit and manageable toxic effects.

OBJECTIVE

To determine the progression-free survival (PFS) at 12 weeks of patients with WD/DDLS treated with palbociclib (PD0332991).

DESIGN, SETTING, AND PARTICIPANTS

In this phase 2, nonrandomized, open-label clinical trial conducted at the Memorial Sloan Kettering Cancer Center, 60 patients 18 years and older with advanced WD/DDLS and measurable disease by RECIST 1.1 were enrolled from December 2011 to January 2014 and followed to March 2015. Patients received oral palbociclib at 125 mg daily for 21 days in 28-day cycles.

MAIN OUTCOMES AND MEASURES

Primary end point was PFS. Secondary end points included response rate and toxic effects.

RESULTS

Overall, 30 patients were enrolled in the initial cohort and 30 more in an expansion cohort. Median (range) age was 61.5 (35-87) years; 31 patients (52%) were male; median (range) Eastern Cooperative Oncology Group score was 0 (0-1). Progression-free survival at 12 weeks was 57.2% (2-sided 95% CI, 42.4%-68.8%), and the median PFS was 17.9 weeks (2-sided 95% CI, 11.9-24.0 weeks). There was 1 complete response. Toxic effects were primarily hematologic and included neutropenia (grade 3, n = 20 [33%]; grade 4, n = 2 [3%]) but no neutropenic fever.

CONCLUSIONS AND RELEVANCE

In patients with advanced WD/DDLS, treatment with palbociclib was associated with a favorable PFS and occasional tumor response. This dose and schedule appears active and may have less toxic effects than 200 mg for 14 days.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01209598.

Combined KIT and CTLA-4 Blockade in Patients with Refractory GIST and Other Advanced Sarcomas: A Phase Ib Study of Dasatinib plus Ipilimumab

Purpose: A phase Ib study of dasatinib plus ipilimumab in patients with gastrointestinal stromal tumor (GIST) and other sarcomas was performed on the basis of preclinical data demonstrating that combined KIT and CTLA-4 blockade is synergistic.Experimental Design: A standard 3 + 3 design was used to evaluate the safety, efficacy, and immune correlates of treatment. Dose escalation cohorts received ipilimumab 10 or 3 mg/kg every 3 weeks, followed by maintenance every 12 weeks with escalating doses of dasatinib (70 mg daily, 100 mg daily, or 70 mg twice daily). Response was assessed by RECIST 1.1, Choi, and immune-related RECIST criteria (irRC).Results: A total of 28 patients (17 male) were enrolled. Histologic subtypes included GISTs (n = 20) and other sarcomas (n = 8.) Dasatinib 70 mg/day with ipilimumab 10 mg/kg or dasatinib 140 mg/day with ipilimumab 3 mg/kg can be safely administered. Dose-limiting toxicities included grade 3 gastric hemorrhage and anemia. No partial or complete responses were noted by RECIST or irRC. There were 7 of 13 partial responses in the GIST patients by Choi criteria, and 3 of 13 patients each had stable and progressive disease, respectively.Conclusions: Dasatinib and ipilimumab can be safely administered to GIST and sarcoma patients. However, dasatinib was not synergistic with ipilimumab, as there was limited clinical efficacy with the combination. This limited cohort provides prospective data that indoleamine-2,3-dioxygenase (IDO) suppression may potentially correlate with antitumor efficacy in GIST. Given the small cohort, it is only hypothesis generating and additional data would be required. In the era of more modern and effective checkpoint inhibitors, next steps could be consideration of tyrosine kinase inhibitors or IDO inhibitors in combination with anti-PD-1 therapy. Clin Cancer Res; 23(12); 2972-80. ©2016 AACR.

Impact of next-generation sequencing (NGS) on diagnostic and therapeutic options in soft-tissue and bone sarcoma

11001

Background: The utility of NGS in management of sarcoma pts remains undefined. Methods: We retrospectively analyzed the NGS profile of patients who were sequenced using a panel of 405 cancer-related genes in DNA and 265 genes rearranged in RNA. Diagnostic and therapeutic implications of mutations (mut) were evaluated through published literature (OncoKb.org, Pubmed). An algorithm was applied to determine germline mut. Following IRB approval, we evaluated the clinical outcomes of pts who underwent NGS at MSKCC. Results: From 2012–2016, 5635 pts worldwide with 56 histologies were tested. Median age of 52 yrs ( < 1-88), 52% females and sarcoma NOS (n = 858) was most frequent. Tumors were sequenced to a mean coverage of 634X; 1165 fusions and > 60,000 mut were found. Mut suspicious for germline defects were seen in 542 pts (9.6%) in known and novel genes ( BRCA, ARID1, FANC). Tumor mutational burden was 2.5/Mb (0–329) and glomus tumors and EHE had the highest and lowest mut, respectively. 16% and 7% of pts had treatment-linked alterations (TLA) known to respond to an FDA approved or study drug, respectively. 42% of pts had TLA eligible for NCI-MATCH, ASCO-TAPUR or other studies. Novel TLA include AKT, ESR1, BRCA, NTRK, PTCH1, SMARCB1 and others. Of the 107 MSKCC pts with clinical data, 60/107 (57%) had at least one TLA, of which 31 (30%) enrolled on a matched trial and 26 pts were ineligible or lacked access to trials. Partial/complete responses were seen with inhibitors to NTRK, IDH1, BRAF, PI3K/mTOR, MDM2, SMARCB1 and others. NGS changed the initial pathology diagnosis and treatments in 5% pts (e.g. LMS to liposarcoma, clear cell to melanoma). Resistance mutations averted futile therapies in 5% pts (e.g. Rb loss and palbociclib in liposarcoma). Conclusions: Our data suggests that NGS has a significant impact in aiding diagnosis and selecting matched therapies in sarcoma. Suspected germline aberrations, while intriguing, needs further validation.

Risk factors associated with ifosfamide (IFOS)-induced encephalopathy in patients (pts) with metastatic (Met) sarcoma (Sarc)

e22518

Background: IFOS is commonly used in the treatment of met sarc. IFOS has been reported to cause encephalopathy in 5 - 30% of pts. Potential risk factors for IFOS-induced encephalopathy (IIE) include female gender, older age, route of administration of IFOS, low serum albumin, existence of pelvic disease and renal failure. Unfortunately, the majority of the data surrounding potential risk factors is from heterogeneous cohorts. Methods: The purpose of this single-center retrospective analysis was to identify risk factors for developing IIE in a homogenous cohort of met sarc pts treated at MSKCC between 1/2010 and 5/2015. Logistic regression was used to examine the univariate effect of baseline and treatment variables. Variables significant at the 0.05 level were entered into a multivariate model. Results: A total of 328 met sarc pts with a median age of 51 years were analyzed. Thirty-four pts (10%) developed IIE. Of those 34 pts, 88% developed encephalopathy with the first or second cycle of IFOS. Age at the time of treatment (p = 0.0037), low serum albumin (p < 0.0001), increased serum alkaline phosphatase (p = 0.0022), liver met disease (p = 0.0011) and more than 3 met sites at time of IFOS dose (p = 0.0008) were all identified as risk factors by univariate analysis. Only low serum albumin (p < 0.0001, odds ratio = 0.33) and more than 3 met sites at time of IFOS dose (p = 0.0068, odds ratio = 2.47) maintained statistical significance after multivariate analysis. Conclusions: To our knowledge, this is the largest retrospective analysis of risk factors for IIE in the met sarc population. This analysis identified low serum albumin and more than 3 met sites at time of IFOS as predictors of IIE. Our data would suggest that clinicians considering the option of IFOS in met sarc pts should give particular attention to these predictive risk factors when making their treatment decisions.

A phase Ib study of BGJ398 in combination with imatinib in patients with advanced gastrointestinal stromal tumor (GIST)

11039

Background: Preclinical studies suggest that imatinib resistance (IR) in GIST can be mediated by MAP-kinase activation via FGF signaling. In FGF stimulated GIST cell lines, BGJ398, a pan-FGFR inhibitor in combination with imatinib, is cytotoxic and superior to imatinib alone, or imatinib in combination with MEK-inhibition. In GIST with FGF signaling, the combination of BGJ398 and imatinib may provide a mechanism to overcome IR. Methods: This phase Ib study of BGJ398 in combination with imatinib was performed in patients (pts) with imatinib resistant advanced GIST. A standard 3+3 dosing schema was utilized to determine the recommended phase II dose. Two treatment schedules were evaluated incorporating imatinib 400mg daily continuously in combination with (A) BGJ daily 3 wks on, 1 wk off or (B) BGJ daily 1 wk on, 3 wks off. Response was evaluated by RECIST and CHOI every 8 wks x4 and then every 12 wks. Results: 16 pts enrolled. Median age 54 (range: 44-77), 81% male, median prior therapy 4 [range: 2-6, 13/16 pts had ≥ 3 prior therapies (81%)]. 12 pts received treatment on schedule A [dose level (DL)1 (BGJ 75mg), n = 6; DL-1 (BGJ 50mg), n = 3; DL-2 (BGJ 25mg), n = 3]: 3 DLTs (myocardial infarction, grade (G)4 CPK elevation, G3 ALT elevation) were observed on schedule A at DL1, hyperphosphatemia (on target effect) was not observed raising concern for therapeutic efficacy at the maximum tolerated dose. Following protocol amendment that allowed an alternative dosing schedule, 4 pts enrolled on schedule B [DL1 (BGJ 75mg), n = 3; DL2 (BGJ 100mg), n = 1]: one DLT occurred (G3 intra-abdominal hemorrhage) at DL2. The most common non-DLT G3/4 toxicity was HTN (2/16pts) and G2 toxicity was prolonged QTc interval (3/16pts). Of the 12 pts with evaluable CT scans, stable disease (SD) was the best response observed in 7 pts by RECIST and 9 pts by CHOI. 3pts achieved SD for > 6 months. 2 pts remain on study at data cut-off (range: 1 – 67 wks). Median progression free survival is 8 weeks. Pharmacokinetic analysis of imatinib and BGJ is forthcoming. Conclusions: In heavily pre-treated pts, durable disease control was observed in 3/16 pts. This signal of efficacy suggests that further evaluation of FGF signaling in the development of IR is warranted. Clinical trial information: NCT02257541.

The clinical impact of performing routine next generation sequencing (NGS) in gastrointestinal stromal tumors (GIST)

11010

Background: The majority of GISTs harbor activating mutations in KIT or PDGFRα but the clinical relevance of other genomic alterations is unknown. We sought to determine the clinical impact of performing routine NGS and to describe the molecular landscape in GIST. Methods: From April 2014 to August 2016, 177 patients (pts) consented to an IRB-approved protocol. Tumor and matched normal samples were prospectively analyzed in a CLIA-compliant laboratory, with MSK-IMPACT, a NGS assay of up to 468 cancer-associated genes. Results: 191 samples were analyzed. NGS was most often performed in the setting of advanced disease (n = 108 (57%)). The primary tumor was most commonly tested (n = 120 (63%)). NGS guided clinical management in 79% (n = 150) of cases [matched therapy (MT) offered, n = 120/150 (80%); MT not offered, n = 24/150 (16%)]. In 25/41 cases (61%) where NGS did not influence management, treatment was not indicated because the GISTs were low risk. Most samples had ≤ 3 mutations (muts) (range: 0-17). Actionable muts were identified in 155/191 samples (81%). These included muts in KIT, PDGFRα and BRAF [oncoKB stratification: level 1 (84%), 2A (13%), 2B (2%), 3A(1%)]. 33/177 pts did not have a KIT/ PDGFRα mut [SDH deficiency, n = 15 (45%), NF1, n = 10 (30%), BRAF, n = 1(3%), NF1&BRAF, n = 1 (3%)]. 5pts had quadruple wild type GIST. Most GISTs had at least one genetic alteration in a non-driver allele (74%, n = 141/191)[frequently mutated genes in KIT exon 11 driven i) primary tumors include TP53, MAX, MLL2, SETD2, PIK3CA, TSC1; and ii) metastatic tumors include RB1, SETD2, PTEN, ANKRD11, TP53, TSC1]. CDKN2A deletion was the most common copy number alteration identified in KIT driven GIST and occurred most often in metastatic samples (with and without co-occurring, secondary KIT muts) and those with high mitotic rate. Conclusions: NGS of GIST informs clinical management in the majority of pts through the identification of muts in canonical driver genes. NGS also identifies a high prevalence of tumor-specific genetic alterations in non-canonical driver genes. These genes function in multiple pathways including intracellular signaling, chromatin remodeling, proteasomal degradation and cell cycle regulation.

Phase II study of MLN8237 (Alisertib) in advanced/metastatic sarcoma

BACKGROUND

Aurora kinase A (AURKA) is commonly overexpressed in sarcoma. The inhibition of AURKA by shRNA or by a specific AURKA inhibitor blocks in vitro proliferation of multiple sarcoma subtypes. MLN8237 (alisertib) is a novel oral adenosine triphosphate-competitive AURKA inhibitor.

PATIENTS AND METHODS

This Cancer Therapy Evaluation Program-sponsored phase II study of alisertib was conducted through the Alliance for Clinical Trials in Oncology (A091102). Patients were enrolled into histology-defined cohorts: (i) liposarcoma, (ii) leiomyosarcoma, (iii) undifferentiated sarcoma, (iv) malignant peripheral nerve sheath tumor, or (v) other. Treatment was alisertib 50 mg PO b.i.d. d1-d7 every 21 days. The primary end point was response rate; progression-free survival (PFS) was secondary. One response in the first 9 patients expanded enrollment in a cohort to 24 using a Simon two-stage design.

RESULTS

Seventy-two patients were enrolled at 24 sites [12 LPS, 10 LMS, 11 US, 10 malignant peripheral nerve sheath tumor (MPNST), 29 Other]. The median age was 55 years; 54% were male; 58%/38%/4% were ECOG PS 0/1/2. One PR expanded enrollment to the second stage in the other sarcoma cohort. The histology-specific cohorts ceased at the first stage. There were two confirmed PRs in the other cohort (both angiosarcoma) and one unconfirmed PR in dedifferentiated chondrosarcoma. Twelve-week PFS was 73% (LPS), 44% (LMS), 36% (US), 60% (MPNST), and 38% (Other). Grade 3-4 adverse events: oral mucositis (12%), anemia (14%), platelet count decreased (14%), leukopenia (22%), and neutropenia (42%).

CONCLUSIONS

Alisertib was well tolerated. Occasional responses, yet prolonged stable disease, were observed. Although failing to meet the primary RR end point, PFS was promising.

TRIAL REGISTRATION ID

NCT01653028.

Phase IB Study of Selinexor, a First-in-Class Inhibitor of Nuclear Export, in Patients With Advanced Refractory Bone or Soft Tissue Sarcoma

PURPOSE

We evaluated the pharmacokinetics (PKs), pharmacodynamics, safety, and efficacy of selinexor, an oral selective inhibitor of nuclear export compound, in patients with advanced soft tissue or bone sarcoma with progressive disease.

PATIENTS AND METHODS

Fifty-four patients were treated with oral selinexor twice per week (on days 1 and 3) at one of three doses (30 mg/m(2), 50 mg/m(2), or flat dose of 60 mg) either continuously or on a schedule of 3 weeks on, 1 week off. PK analysis was performed under fasting and fed states (low v high fat content) and using various formulations of selinexor (tablet, capsule, or suspension). Tumor biopsies before and during treatment were evaluated for pharmacodynamic changes.

RESULTS

The most commonly reported drug-related adverse events (grade 1 or 2) were nausea, vomiting, anorexia, and fatigue, which were well managed with supportive care. Commonly reported grade 3 or 4 toxicities were fatigue, thrombocytopenia, anemia, lymphopenia, and leukopenia. Selinexor was significantly better tolerated when administered as a flat dose on an intermittent schedule. PK analysis of selinexor revealed a clinically insignificant increase (approximately 15% to 20%) in drug exposure when taken with food. Immunohistochemical analysis of paired tumor biopsies revealed increased nuclear accumulation of tumor suppressor proteins, decreased cell proliferation, increased apoptosis, and stromal deposition. Of the 52 patients evaluable for response, none experienced an objective response by RECIST (version 1.1); however, 17 (33%) showed durable (≥ 4 months) stable disease, including seven (47%) of 15 evaluable patients with dedifferentiated liposarcoma.

CONCLUSION

Selinexor was well tolerated at a 60-mg flat dose on a 3-weeks-on, 1-week-off schedule. There was no clinically meaningful impact of food on PKs. Preliminary evidence of anticancer activity in sarcoma was demonstrated.

Prevalence of tumor-infiltrating lymphocytes and PD-L1 expression in the soft tissue sarcoma microenvironment

The prognostic and predictive implications of programmed death-ligand 1 (PD-L1) is unknown in sarcoma. We sought to examine the immune milieu in sarcoma specimens. We evaluated PD-L1 expression by immunohistochemistry in sarcoma specimens and quantified tumor-infiltrating lymphocytes (TIL). We correlated expression with clinical parameters and outcomes. Fifty sarcoma patients treated at Memorial Sloan Kettering Cancer Center were selected. Using the DAKO PD-L1 immunohistochemistry assay and archival formalin-fixed paraffin-embedded tissue specimens; PD-L1 expression was examined. Macrophage and lymphocyte PD-L1 status was determined qualitatively. TIL was quantified. Associations between PD-L1 expression in tumor, macrophages and lymphocytes, TIL and clinical-pathological characteristics were performed. The median age was 46 years (range, 22-76), and 66% of patients were men. Tumor, lymphocyte and macrophage PD-L1 expression was noted in 12%, 30% and 58%, respectively, with the highest prevalence in gastrointestinal stromal tumors (29%). Lymphocyte and macrophage infiltration was present in 98% and 90%, respectively. There was no association between clinical features, overall survival and PD-L1 expression in tumor or immune infiltrates. Lymphocyte and macrophage infiltration is common in sarcoma, but PD-L1 tumor expression is uncommon in sarcoma with the highest frequency observed in gastrointestinal stromal tumors. There was no association between PD-L1 expression, TIL and clinicopathological features and overall survival; however, this is limited by the heterogenous patient sample and minimal death events in the studied cohort.

High-risk features in radiation-associated breast angiosarcomas

BACKGROUND

Radiation-associated breast angiosarcoma (RT-AS) is an uncommon malignancy with an incidence of less than 1 % of all soft tissue sarcomas. The overall prognosis is quite dismal with high rates of recurrences and poor overall survival. There is an obvious paucity of data regarding clinical outcomes of patients with breast RT-AS.

METHODS

We identified all patients with RT-AS treated at the Memorial Sloan-Kettering Cancer Center between 1982-2011 and collected their correlative clinical information.

RESULTS

We identified 79 women with RT-AS with a median age of 68 (range 36-87). The median interval between radiation and development of RT-AS was 7 years (range 3-19). The median time to local and distant recurrence was 1.29 years (95 % CI 0.72-NA) and 2.48 years (95 % CI 1.29-NA), respectively. The median disease-specific survival was 2.97 years (95 % CI 2.21-NA). Independent predictors of worse disease-specific survival included age 68 years (HR 3.11, 95 % CI 1.20-8.08, P=0.020) and deep tumors (HR 3.23, 95 % CI 1.02-10.21, P=0.046.)

CONCLUSION

RT-AS has high local/distant recurrence rates, limited duration on standard chemotherapy and poor disease-specific survival.

Phase II trial of the CDK4 inhibitor PD0332991 in patients with advanced CDK4-amplified well-differentiated or dedifferentiated liposarcoma

PURPOSE

CDK4 is amplified in > 90% of well-differentiated (WDLS) and dedifferentiated liposarcomas (DDLS). The selective cyclin-dependent kinase 4 (CDK4)/CDK6 inhibitor PD0332991 inhibits growth and induces senescence in cell lines and xenografts. In a phase I trial of PD0332991, several patients with WDLS or DDLS experienced prolonged stable disease. We performed an open-label phase II study to determine the safety and efficacy of PD0332991 in patients with advanced WDLS/DDLS.

PATIENTS AND METHODS

Patients age ≥ 18 years experiencing disease progression while receiving systemic therapy before enrollment received PD0332991 200 mg orally once per day for 14 consecutive days in 21-day cycles. All were required to have CDK4 amplification by fluorescence in situ hybridization and retinoblastoma protein (RB) expression by immunohistochemistry (≥ 1+). The primary end point was progression-free survival (PFS) at 12 weeks, with 12-week PFS of ≥ 40% considered promising and ≤ 20% not promising. If ≥ nine of 28 patients were progression free at 12 weeks, PD0332991 would be considered active.

RESULTS

We screened 48 patients (44 of 48 had CDK4 amplification; 41 of 44 were RB positive). Of those, 30 were enrolled, and 29 were evaluable for the primary end point. Grade 3 to 4 events included anemia (17%), thrombocytopenia (30%), neutropenia (50%), and febrile neutropenia (3%). At 12 weeks, PFS was 66% (90% CI, 51% to 100%), significantly exceeding the primary end point. The median PFS was 18 weeks. There was one partial response.

CONCLUSION

Treatment with the CDK4 inhibitor PD0332991 was associated with a favorable progression-free rate in patients with CDK4-amplified and RB-expressing WDLS/DDLS who had progressive disease despite systemic therapy.

A phase Ib/II study of imatinab and everolimus in patients with PDGFRA+ synovial sarcoma

10558

Background: Our group previously reported that PDGFRA is the most highly overexpressed kinase gene in synovial sarcoma. Our preclinical studies also demonstrated synergistic anti-tumor activity by inhibiting both PDGFRA and mTOR signaling with imatinib and rapamycin respectively in PDGFRA + synovial sarcoma cell lines. Based on these data, a phase Ib/II study to evaluate the toxicity and efficacy of imatinib and everolimus was undertaken. Methods: The primary endpoint of the phase 1b portion of the study was to determine the maximum tolerated dose (MTD) of everolimus administered with imatinib. Starting dose of everolimus and imatinib was 5 mg/day and 400 mg/day respectively. Response rate (RR) by RECIST was the primary end-point of the Phase II study. The phase II study used a Simon two stage design. 9 patients (pts) were to be accrued initially. If there were no responses, further accrual would be stopped and treatment declared ineffective. If there was at least 1 response, an additional 15 pts would be accrued for a total of 24. Key eligibility: metastatic disease, any number of priors. Pre and post treatment tumor biopsies were mandated. Results: 12 pts were treated.5 M and 7 F, median age 44 (range: 22-71), median priors 4 (range: 0 - 6). Two DLTs were observed at dose level 2 (10 mg everolimus /400 mg imatinib) with grade 3 transaminases and hypophosphatemia. Everolimus 5 mg/ imatinib 400 mg was the MTD in the phase II study. 10 pts evaluable for response, included 4 pts treated at the MTD in the Phase 1b study. There were no RECIST responses. Stable disease was observed in 3 pts (7, 7, 19 mos.). Western blot and IHC analysis of matched pair tumor biopsies indicate inhibition of p-AKT, p-S6 and decreases in Ki 67. Conclusions: Imatinib and everolimus failed to achieve its primary response endpoint. However, prolonged stable disease in 3 pts in association with inhibition of PDGFRA and mTOR suggest clinical benefit and biological effect for this drug combination. Clinical trial information: CTEP 8603.

Phase II trial of the CDK4 inhibitor PD0332991 in patients with advanced CDK4-amplified liposarcoma

10512

Background: Approximately 90% of well-differentiated / de-differentiated liposarcomas (WD/DDLS) have CDK4 amplification. The selective CDK4/CDK6 inhibitor PD0332991 inhibits growth and induces senescence in liposarcoma cell lines and xenografts. Our prior phase II study demonstrated that treatment with PD0332991 (200mg daily x 14d every 21d) results in clinical benefit in WD/DDLS but moderate hematologic toxicity (48% Grade 3/4 neutropenia; dose reduction in 24%). Aiming to reduce toxicity, we conducted a phase II study to assess progression-free survival (PFS) and toxicity with PD0332991 at a new dose and schedule, 125mg daily x 21d every 28d. Methods: Participants were patients with advanced WD/DDLS. Eligibility criteria were age ≥ 18 years, measurable WD/DDLS (RECIST 1.1), documented progression on at least one systemic therapy directly before enrollment, CDK4 amplification by fluorescence in situ hybridization and retinoblastoma protein expression by immunohistochemistry (≥1+). Pts received oral PD0332991 at 125mg daily for 21 days in 28-day cycles. The primary endpoint was PFS at 12 weeks. Based on historical data, a promising result was defined as a 12-week PFS of ≥40% and not promising as ≤20%. The sample size was up to 28 evaluable patients. If 9 patients were progression free at 12 weeks, then PD0332991 would be considered to have activity in WD/DDLS. Results: 29 pts were enrolled and 25 were evaluable for the primary endpoint. Median age was 62 (range 42-85); 55% were male; median ECOG score was 0 (range 0-1). PFS at 12 weeks was 56% (14/25 patients; 90% CI 41-100%), and thus the study significantly exceeded its primary endpoint. Median PFS was 23.6 weeks (95% CI: 11.6 to Not Reached). There was 1 confirmed partial response lasting > 1 year. Grade 3 and 4 adverse events included anemia (grade 3, 21%), thrombocytopenia (grade 3, 7%; grade 4, 3%), and neutropenia (grade 3, 34%). Dose reduction was required in only 1 patient. Conclusions: In patients with WD/DDLS with CDK4 amplification, PD0332991 treatment was associated with a favorable PFS and objective tumor response. This dose and schedule appears active and may have less toxicity than 200mg x 14d. The 125mg x 21d schedule warrants evaluation in a phase 3 study. Clinical trial information: NCT01209598.

Poor prognostic features in angiosarcoma: A single institution retrospective study of 324 patients

10580

Background: Angiosarcoma (AS) is a rare, malignant endothelial cell tumor of vascular origin with a five year overall survival (OS) of approximately 35%. It is a heterogenous disease whose natural history is poorly defined. We sought to identify clinical and treatment outcomes to better define this disease. Methods: In a retrospective study using an institutional sarcoma database, we identified all patients(pts) with AS treated at Memorial Sloan-Kettering Cancer Center between 1992-2011 and collected their correlative clinical information.Kaplan-Meier method and Cox’s proportional-hazard models were used to determine OS and prognostic factors. Hazard ratios (HR) are listed with their 95%confidence intervals (CI). Results: We identified 324 pts, median age was 63 (range 15-94), 127(39%) were men. At presentation, 188 (58%), 19 (6%) and 117(36%) had localized disease (L), local recurrences (LR) or distant metastases (M), respectively. L sites included: RT breast 43 (23%,) head&neck 33 (18%,) scalp 30 (16%,) breast 26 (14%,) extremity 23 (12%,) abdomen/pelvis 14 (7%,) thorax 10 (5%) and trunk 9 (5%). The median OS is 3.3 years (2.44-4.33) for pts w L disease and 0.89 years (0.74-1.11) for pts with M disease. Among pts that presented with L disease, 29% had a LR and the median local relapse free survival (RFS) time was not reached (8.71-NA); 31% had distant recurrences with a median distant RFS of 12.8 yrs (4.13-NA.) Among L disease patients, older age (HR 1.04, 1.03-1.06, p <0.0001) and site were independent predictors of decreased OS. Visceral tumors arising in the abdominal/pelvis (AP) (HR 2.89, 1.27-6.61, p = 0.012) had worse OS compared to those arising the breast. Conclusions: AS remains an aggressive, heterogenous malignancy with poor OS and high rates of local and distant recurrences. Patients with M disease do poorly. Adverse prognostic factors include AP visceral tumors and older age. These factors could be helpful for stratification in future clinical trials. The identification of genomic differences is necessary to define therapeutic targets in AS.

Adult rhabdomyosarcoma survival improved with treatment on multimodality protocols

PURPOSE

Rhabdomyosarcoma (RMS) is a pediatric sarcoma rarely occurring in adults. For unknown reasons, adults with RMS have worse outcomes than do children.

METHODS AND MATERIALS

We analyzed data from all patients who presented to Memorial Sloan-Kettering Cancer Center between 1990 and 2011 with RMS diagnosed at age 16 or older. One hundred forty-eight patients met the study criteria. Ten were excluded for lack of adequate data.

RESULTS

The median age was 28 years. The histologic diagnoses were as follows: embryonal 54%, alveolar 33%, pleomorphic 12%, and not otherwise specified 2%. The tumor site was unfavorable in 67% of patients. Thirty-three patients (24%) were at low risk, 61 (44%) at intermediate risk, and 44 (32%) at high risk. Forty-six percent were treated on or according to a prospective RMS protocol. The 5-year rate of overall survival (OS) was 45% for patients with nonmetastatic disease. The failure rates at 5 years for patients with nonmetastatic disease were 34% for local failure and 42% for distant failure. Among patients with nonmetastatic disease (n=94), significant factors associated with OS were histologic diagnosis, site, risk group, age, and protocol treatment. On multivariate analysis, risk group and protocol treatment were significant after adjustment for age. The 5-year OS was 54% for protocol patients versus 36% for nonprotocol patients.

CONCLUSIONS

Survival in adult patients with nonmetastatic disease was significantly improved for those treated on RMS protocols, most of which are now open to adults.

Phase II study of the HSP90-inhibitor BIIB021 in gastrointestinal stromal tumors

BACKGROUND

HSP90 inhibition leads to proteosomal degradation of activated KIT and has in vitro activity against gastrointestinal stromal tumors (GIST). BIIB021 is an oral non-ansamycin HSP90 inhibitor. We carried out a phase II study of BIIB021 in patients with GIST refractory to imatinib and sunitinib.

PATIENTS AND METHODS

The primary end-point was metabolic partial response (mPR) as assessed by fluorodeoxyglucose positron emission tomography (FDG-PET). The secondary end-points were pharmacokinetic assessments of BIIB021 and pharmacodynamic assessments of HSP70. Twenty-three patients were treated on two schedules: 12 pts received 600 mg twice a week (BIW) and 11 patients received 400 mg three times a week (TIW). All had prior imatinib and sunitinib but stopped>14 days before starting BIIB021.

RESULTS

The median age was 59 years (33-88 years), 61% male, 44% Eastern Cooperative Oncology Group 1 (ECOG1). The best response was PR by FDG-PET for five patients (3/12 at 600 mg BIW and 2/9 at 400 TIW) for an overall response rate of 22%. The response duration was 25-138 days. Adverse events (AEs) were mild to moderate. The mean Cmax was 1.5 µmol and the mean AUC was 2.9 µmol h. Cmax>1.5 µmol was associated with a decrease in standardized uptake value (SUVmax). HSP70 increased substantially following treatment.

CONCLUSIONS

This study met its primary end-point. BIIB021 leads to objective responses in refractory GIST patients. Pharmacodynamic studies confirmed HSP90 inhibition. Further evaluation of BIIB021 in GIST is warranted.

Advances in the systemic treatment of cutaneous sarcomas

Cutaneous sarcomas are a rare subset of soft tissue sarcomas. These tumors are primarily managed with definitive surgical resection; however, upon unresectable recurrence or metastatic spread, systemic therapy is warranted. As with other sarcomas, these treatments have classically included cytotoxic chemotherapy programs that were associated with variable response rates and poor overall survival. Recently, major advances have been made in the understanding of the molecular biology of these tumors, and treatment paradigms are changing. Multiple pathways have been documented to be important in the growth of cutaneous sarcomas, including receptor tyrosine kinases such as platelet-derived growth factor receptor, insulin-like growth factor receptor and KIT. Dysregulated angiogenesis, through vascular endothelial growth factor (VEGF) and other pathways, is also associated with the growth of these tumors. In this review, we discuss the current standard therapies of cutaneous sarcoma and the recent advances and ongoing investigations into cutaneous sarcoma biology.