A phase II study of atezolizumab (atezo) with or without bevacizumab (bev) versus sunitinib (sun) in untreated metastatic renal cell carcinoma (mRCC) patients (pts)

431

Background: While targeting VEGF improves outcomes for mRCC pts, resistance invariably develops, often within the first year. Here, we describe the efficacy and safety of atezo (anti-PD-L1) with bev (anti-VEGF) and atezo monotherapy vs sun (TKI) in first-line mRCC. Methods: Treatment-naïve mRCC pts were enrolled in a hypothesis generating Ph II study (IMmotion150; NCT01984242) and randomized to atezo 1200 mg IV q3w + bev 15 mg/kg IV q3w, atezo alone or sun 50 mg PO QD 4 wk on/2 wk off. Crossover to atezo + bev after disease progression was allowed for pts receiving atezo or sun. PD-L1 expression was scored on tumor-infiltrating immune cells (IC, SP142 IHC assay). Coprimary endpoints were PFS (RECIST v1.1 by independent review [IRF]) in ITT pts and pts with PD-L1 expression on ≥ 1% of IC (PD-L1+). Results: Baseline characteristics were comparable across arms and between ITT and PD-L1+ pts. The majority of sun and atezo pts subsequently received atezo + bev. Median survival follow up was 20.7 mo. The PFS HR in ITT pts for atezo + bev vs sun was 1.00 and 1.19 for atezo vs sun. In PD-L1+ pts, the PFS HR for atezo + bev vs sun was 0.64 and 1.03 for atezo vs sun (table). Tx-related Gr 3-4 AEs were seen in 40%, 16% and 57% of pts in the atezo + bev, atezo and sun arms, respectively. AEs leading to death occurred in 3%, 2% and 2% of pts, respectively. Conclusion: Atezo + bev resulted in encouraging antitumor activity in the PD-L1+ subgroup of first-line RCC pts. Atezo + bev safety is consistent with the known profile of atezo and bev individually. The clinical benefit of atezo + bev vs sun will be evaluated in the ongoing Ph III study IMmotion151 (NCT02420821). Clinical trial information: NCT01984242. [Table: see text]

Abstract P4-22-09: A phase 2 open label study of everolimus in combination with endocrine therapy in resistant hormone receptor-positive HER2-negative advanced breast cancer

Background: Therapies targeting estrogen receptor (ER) signaling are standard for patients (pts) with hormone receptor positive (HR+) (ER and/or progesterone receptor [PR] positive) metastatic breast cancer (MBC). Dysregulation of the mammalian target of rapamycin (mTOR) pathway has been associated with endocrine therapy (ET) resistance. BOLERO-2 demonstrated that the addition of the mTOR inhibitor, everolimus (EVE), to exemestane doubled the PFS in HR+ HER2- MBC pts who previously progressed on nonsteroidal aromatase inhibitor therapy.The premise of this phase 2 trial in HR+ MBC is that the addition of EVE to the last ET on which the disease progressed may restore sensitivity to ET and extend the benefit of the anti-estrogen therapy.

Methods: Pts ≥18 yrs with HR+, HER2- unresectable, locally recurrent, or MBC refractory to ET in either the adjuvant or advanced/metastatic setting. 0-1 chemotherapy (chemo) regimens for MBC were permitted. Post-/ pre-/peri-menopausal women were eligible with ovarian function suppression permitted. Additional eligibility requirements include: no prior mTOR inhibitor therapy, measurable or evaluable disease, ECOG ≤2, adequate bone marrow and organ function. EVE (10 mg PO daily) was administered on a 4-wk cycle in combination with the same dose and schedule of the last ET to which their disease became resistant. Disease assessments were performed every 2 cycles and treatment continued until disease progression or unacceptable toxicity. Blood samples and archival tumor were collected respectively for the VeriStrat Assay and for the Foundation One molecular profiling platform.

Results: 48 pts were enrolled; data from 26 pts is presented. Median age 63.5 yrs (range, 36-81) with 46% ≥ 65 yrs. 14 (54%) pts had received chemo in the adjuvant setting, 9 pts (35%) received chemo for MBC, and 4 pts (15%) received chemo in both settings. All pts had at least 1 prior hormonal therapy; 9 pts received ≥ 3 hormonal agents. EVE was combined with tamoxifen (27%), AIs (61%), and fulvestrant (12%). Median time on treatment was 18.6 wks (range 1-48.9 weeks). 5 pts (19%) remain on treatment and 21 (81%) have discontinued therapy due to: disease progression - 17, toxicity -2, and other causes - 2. 23 pts were evaluable for response. 1 pt on fulvestrant plus EVE had a PR and 18 pts (78%) had SD as best response, with SD > 6 mos in 7 pts, for a clinical benefit rate (CR+PR+ SD ≥ 6 months) of 35%. With a median follow up of 11 mos (range 2-16 mos), the median PFS was 6.6 months (range 3.6-9.4); the median OS has not been reached. Treatment-related adverse events consisted mostly of stomatitis, rash and fatigue with few G3 events: stomatitis 3 pts, rash 2 pts, and 1 each of fatigue, edema, and neutropenia. G1 pneumonitis was present in 2 pts. There were no G4 events or treatment related deaths.

Conclusions: In HR+ HER2- advanced/MBC patients who progressed on prior ET, the addition of EVE to the ET to which their disease became resistant, resulted in 1 PR and 7 pts with SD > 6 mos. The results of the full study population will be presented. Modulation of the mTOR/AKT/PI3K pathway with EVE may extend the benefit of ET, even after tumor progression on ET alone.

Citation Format: Yardley DA, Blakely L, Hemphill B, Joseph M, Liggett W, Daniel B, Castrellon A, Shastry M, Finney L, DeBusk L, Hainsworth JD, Burris III HA. A phase 2 open label study of everolimus in combination with endocrine therapy in resistant hormone receptor-positive HER2-negative advanced breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-09.

Pertuzumab + trastuzumab for HER2-positive metastatic biliary cancer: Preliminary data from MyPathway

402

Background: Biliary cancers have a high mortality rate, with limited treatment options. While HER2 is overexpressed in 9-20% of biliary cancers, it has not been fully explored as a therapeutic target. MyPathway is a multi-basket study evaluating the efficacy and safety of targeted therapies in non-indicated tumor types harboring relevant genetic alterations. We present preliminary data for patients with HER2-positive metastatic biliary cancer receiving HER2-targeted treatment with pertuzumab + trastuzumab. Methods: MyPathway (NCT02091141) is an open-label, multicenter, phase IIA study. Patients in this subset analysis had refractory metastatic biliary cancer with HER2 amplification/overexpression or putative activating mutations by gene sequencing, FISH, or IHC. Patients received standard doses of pertuzumab + trastuzumab until disease progression or unacceptable toxicity. The primary endpoint is investigator-assessed overall response rate (RECIST v1.1). Results: As of July 31, 2016, 11 patients with HER2-positive biliary cancer (HER2-amplified/overexpressed, n = 8; HER2-mutated, n = 3 [D277Y, S310F, and A775-G776insYVMA]) have been enrolled. At a median follow-up of 4.2 (range 2.0–12.0) months, 4 patients had partial responses (PR) and 3 had stable disease (SD) for > 4 months (Table). Safety was consistent with the package inserts. Conclusions: Preliminary results indicate that pertuzumab + trastuzumab has activity in HER2 amplified/overexpressed/mutated metastatic biliary tumors, suggesting HER2 as a therapeutic target for these rare cancers. Accrual to MyPathway is ongoing. Clinical trial information: NCT02091141. [Table: see text]

Pertuzumab + trastuzumab for HER2-amplified/overexpressed metastatic colorectal cancer (mCRC): Interim data from MyPathway

676

Background: Among recent advances in precision medicine, HER2 has emerged as a potential therapeutic target for advanced colon cancer. MyPathway is a multi-basket study evaluating the efficacy and safety of targeted therapies in non-indicated tumor types harboring relevant genetic alterations. We present updated data for an expanded cohort of patients with HER2-amplified/overexpressed mCRC receiving HER2-targeted therapy with pertuzumab + trastuzumab. Methods: MyPathway (NCT02091141) is a multicenter, open-label, phase IIA study. Patients in this analysis had treatment-refractory HER2-amplified/overexpressed mCRC by gene sequencing, FISH, or IHC. Patients received standard doses of pertuzumab + trastuzumab until disease progression or unacceptable toxicity. The primary endpoint is investigator-assessed overall response rate. The cutoff date was July 31, 2016. Results: Of 34 patients with mCRC enrolled, 32 have had ≥1 tumor assessment. At a median follow-up of 5.2 (range 0.7–18.3) months from treatment initiation, 12 patients had partial responses (PR), with stable disease (SD) for >4 months in 3 additional patients (Table). The safety profiles were consistent with the product labels. Conclusions: Interim data show that HER2-targeted therapy with pertuzumab + trastuzumab, a chemotherapy-free regimen, is active in heavily pretreated HER2-amplified/overexpressed mCRC. The ORR was 37.5%, responses were durable (median 11.1 months), and the CBR was 46.9%. Accrual to MyPathway is ongoing. Clinical trial information: NCT02091141. [Table: see text]

A phase 2 study of the sphingosine-1-phosphate antibody sonepcizumab in patients with metastatic renal cell carcinoma

BACKGROUND

Upregulation of sphingosine-1-phosphate (S1P) may mediate resistance to vascular endothelial growth factor (VEGF)-directed therapies and inhibit antitumor immunity. Antagonism of S1P in preclinical models appears to overcome this resistance. In this phase 2 study, the authors assessed the activity of sonepcizumab, a first-in-class inhibitor of S1P, in patients with metastatic renal cell carcinoma (mRCC) with a history of prior VEGF-directed therapy.

METHODS

Patients were required to have clear cell mRCC and to have received treatment with at least 1 prior VEGF-directed agent. Prior treatment with immunotherapeutic agents and ≤1 mammalian target of rapamycin inhibitors was permitted. The primary endpoint of the study was progression-free survival. Additional endpoints included response rate and safety, and overall survival (OS) performed post hoc.

RESULTS

A total of 40 patients were enrolled with a median of 3 prior therapies (range, 1-5 prior therapies), 78% of whom had intermediate-risk disease by second-line International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) criteria. Although the current study did not achieve its primary endpoint based on the 2-month progression-free survival, a median OS of 21.7 months was observed. Four patients (10%) demonstrated a partial response, with a median duration of response of 5.9 months. No grade 3/4 treatment-related adverse events were observed in >5% of patients (adverse events were graded and recorded for each patient using Common Terminology Criteria for Adverse Events [version 4.0]); the most frequent grade 1/2 treatment-related adverse events were fatigue (30%), weight gain (18%), constipation (15%), and nausea (15%). Biomarker studies demonstrated an increase in S1P concentrations with therapy. Comprehensive genomic profiling of 3 patients with a clinical benefit of >24 months indicated von Hippel-Lindau (VHL) and polybromo-1 (PBRM1) alterations.

CONCLUSIONS

The encouraging OS and favorable safety profile observed with sonepcizumab should prompt further investigation of the agent in combination with VEGF-directed agents or checkpoint inhibitors. Cancer 2017;123:576-582. © 2016 American Cancer Society.

Circulating Tumor Cells in a Phase 3 Study of Docetaxel and Prednisone with or without Lenalidomide in Metastatic Castration-resistant Prostate Cancer

Elevated circulating tumor cell (CTC) blood levels (≥5 cells/7.5ml) convey a negative prognosis in metastatic castration-resistant prostate cancer but their prognostic significance in patients receiving chemotherapy is uncertain. The association between CTC counts (at baseline or after treatment), overall survival (OS), and response to docetaxel with lenalidomide was evaluated in a 208-patient subset from the MAINSAIL trial, which compared docetaxel-prednisone-lenalidomide and docetaxel-prednisone-placebo in metastatic castration-resistant prostate cancer patients. Baseline CTCs were <5 cells/7.5ml blood in 87 (42%) patients and ≥5 cells/7.5ml in 121 (58%) patients. Neither tumor response nor prostate-specific antigen response correlated with baseline CTCs. However, CTC count ≥5 cells/7.5ml was significantly associated with lower OS (hazard ratio: 3.23, p = 0.0028). Increases in CTCs from <5 cells/7.5ml to ≥5 cells/7.5ml after three cycles were associated with significantly shorter OS (hazard ratio: 5.24, p=0.025), whereas CTC reductions from ≥5 cells/7.5ml to <5 cells/7.5ml were associated with the best prognosis (p=0.003).

PATIENT SUMMARY

Our study in metastatic castration-resistant prostate cancer patients treated with docetaxel chemotherapy, with or without lenalidomide, showed that patient survival was best predicted by circulating tumor cell count at the start of treatment. A rising circulating tumor cell count after three cycles of therapy predicted poor survival, while a decline predicted good survival.

Targeted therapy for advanced solid tumors based on molecular profiles: Early results from MyPathway, an open-label, phase IIa umbrella basket study

LBA11511

Background: The MyPathway study (NCT02091141) evaluates agents targeting the HER2, BRAF, Hedgehog (Hh), or EGFR pathways in non-indicated tumors with relevant genetic abnormalities. Early results from MyPathway merit pre-planned tumor-cohort expansion. Methods: Eligible pts had advanced solid tumors with no curative therapy and molecular alterations in HER2, BRAF, Hh, or EGFR. Pts received standard doses of trastuzumab + pertuzumab (for the HER2 pathway), vemurafenib (BRAF), vismodegib (Hh), or erlotinib (EGFR) based on alteration. The primary endpoint is investigator-evaluated response rate within a tumor-pathway cohort (RECIST 1.1). Cohort size and expansion is determined by Simon’s two-stage design criteria. Results: By December 14, 2015, MyPathway included 129 pts with available baseline assessments and alterations in HER2 (n = 82; 53 amplifications, 23 mutations, 5 both, 1 RBMS-NRG1 fusion), BRAF (n = 33; 18 V600E, 15 other), Hh (n = 8; 7 PTCH1, 1 SMO), or EGFR (n = 6). Pts had a median of 3 (range, 0–10) prior lines of therapy. Best responses (n = 118) are shown below; 11 pts had insufficient follow-up for reevaluation and were not analyzed. 22 pts had PR/CR (1 CR); current response durations were up to 11 months. Conclusions: Targeted therapy produced responses in pts with 9 different tumor types outside of current drug indications. As enrollment increases for all tumor-pathway cohorts, analyses of tumor responses based on specific alterations (eg, HER2 amplifications vs. mutations) are planned. The HER2 amplified colorectal, bladder, and biliary, and the BRAF lung cohorts will be expanded based on observed activity. Clinical trial information: NCT02091141. [Table: see text]

Lung Adenocarcinoma with Anaplastic Lymphoma Kinase (ALK) Rearrangement Presenting as Carcinoma of Unknown Primary Site: Recognition and Treatment Implications

Background

Molecular cancer classifier assays are being used with increasing frequency to predict tissue of origin and direct site-specific therapy for patients with carcinoma of unknown primary site (CUP).

Objective

We postulated some CUP patients predicted to have non-small-cell lung cancer (NSCLC) by molecular cancer classifier assay may have anaplastic lymphoma kinase (ALK) rearranged tumors, and benefit from treatment with ALK inhibitors.

Methods

We retrospectively reviewed CUP patients who had the 92-gene molecular cancer classifier assay (CancerTYPE ID; bioTheranostics, Inc.) performed on tumor biopsies to identify patients predicted to have NSCLC. Beginning in 2011, we have tested these patients for ALK rearrangements and epidermal growth factor receptor (EGFR) activating mutations, based on the proven therapeutic value of these targets in NSCLC. We identified CUP patients with predicted NSCLC who were subsequently found to have ALK rearrangements.

Results

NSCLC was predicted by the molecular cancer classifier assay in 37 of 310 CUP patients. Twenty-one of these patients were tested for ALK rearrangements, and four had an EML4-ALK fusion gene detected. The diagnosis of lung cancer was strongly suggested in only one patient prior to molecular testing. One patient received ALK inhibitor treatment and has had prolonged benefit.

Conclusions

We report on patients with lung adenocarcinoma and ALK rearrangements originally diagnosed as CUP who were identified using a molecular cancer classifier assay. Although ALK inhibitors treatment experience is limited, this newly identifiable group of lung cancer patients should be considered for therapy according to guidelines for stage IV ALK-positive NSCLC.

Abstract P1-14-06: A phase II randomized study with eribulin/cyclophosphamide (ErC) and docetaxel/cyclophosphamide (TC) as neoadjuvant therapy in HER2-negative breast cancer- Final analysis of primary endpoint and correlative analysis results

Background: Eribulin mesylate (Er) is a non-taxane inhibitor of microtubule growth that results in G2-M cell cycle arrest, disruption of normal mitotic spindles and apoptosis. Er demonstrated an overall survival (OS) but not progression free survival (PFS) advantage in anthracycline and taxane refractory breast cancer pts. This OS rather than PFS benefit has been attributed to Er's potential to suppress new metastases through its effects on the epithelial mesenchymal transition (EMT) pathway, even in the absence of an effect on the primary tumor or established metastases. In this study ErC was compared to TC, a standard regimen for (neo) adjuvant treatment. A companion exploratory analysis examined the EMT markers E-cadherin and vimentin, as well as the endothelial marker CD-31 assessing tumor vasculature. Final assessments of the primary endpoint of pathological complete response (pCR) and results of the correlative studies will be presented.

Methods: Women with histologically confirmed invasive HER2-negative (IHC 0-1+ or FISH/SISH negative), cT1-3, cN0-2, M0 (pN3a disease allowed) adenocarcinoma of the breast were eligible. Following a 10 pt lead-in to confirm the safety/feasibility of ErC, pts were randomized 2:1. Arm 1, Er 1.4 mg/m2 IV (Days 1 & 8) and C 600 mg/m2 IV (Day 1); Arm 2, T 75 mg/m2 IV and C 600 mg/m2 IV on Day 1, both regimens administered q 21 days x 6 cycles followed by surgery. Tumor samples were collected at baseline and from residual breast cancer at the time of surgery. Samples were assayed for E-cadherin, vimentin, and CD-31 expression by immunohistochemistry.

Results: Enrollment was completed 4/2014 (76 pts); 10 pts in lead-in phase, 66 pts were randomized (Arm 1, 44; Arm 2, 22). In the randomized population, 77% had invasive ductal adenocarcinoma; median tumor size 3.1 cm (range, 0.4-10cm; 29.5% were T3); axillary nodes clinically positive in 52%. 34% of pts were triple negative (TN). 59 pts (89%) underwent surgery after receiving neoadjuvant chemotherapy (NAC) on study. pCR rates were 9% and 18% on the TC and ErC arms respectively. 4/7 pts with pCR on the ErC arm were TN. tumor samples were analyzed from 69 pts (including lead-in pts) for expression of the EMT biomarkers. Of these, 40 pts had paired pre- and post-treatment samples, and 29 pts had either a pre- or post-treatment sample (including 8 pre-treatment samples from pts who achieved pCR). In pre-treatment tumor specimens (61 samples), E-cadherin levels were modest-high in 80%, vimentin expression was seen in 39%, and CD-31 expression observed in 21% of the samples. Analysis of pre- and post-treatment paired specimens and differential effects according to treatment regimen will be presented.

Conclusion: The observed pCR rate of 18% with ErC in this HER2- pt population was comparable with other NAC regimens. Correlative evaluation of EMT markers and tumor vascular density with response is ongoing and will be presented.

Citation Format: Yardley DA, Chandra P, Hart L, Wright GS, Ward P, Mani A, Shastry M, Finney L, Guo S, DeBusk LM, Hainsworth JD, Burris III HA. A phase II randomized study with eribulin/cyclophosphamide (ErC) and docetaxel/cyclophosphamide (TC) as neoadjuvant therapy in HER2-negative breast cancer- Final analysis of primary endpoint and correlative analysis results. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-06.

Abstract P1-12-04: A phase 2 study of eribulin in breast cancer not achieving a pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC)

Background: Residual breast cancer after NAC is associated with a high risk of recurrence. Little evidence supports the use of further chemotherapy in this setting. Eribulin, an inhibitor of microtubule dynamics, demonstrated a survival advantage in patients with metastatic breast cancer who had progressed after previous anthracycline and taxane therapy. This phase 2 trial assessed the efficacy of eribulin (2-yr disease-free survival) administered postoperatively to breast cancer pts not achieving a pCR following standard NAC.

Methods: Women with invasive breast cancer (stage T1-4b, N0-2, M0 at diagnosis) and evidence of residual cancer (&gt;5 mm) in the breast or axillary lymph nodes (LN) following ≥4 cycles of standard anthracycline and/or taxane-containing NAC were eligible. Additional eligibility criteria: age ≥18 yrs, peripheral neuropathy &lt; 1, adequate hematologic, hepatic, and renal function. 3 groups were studied: Cohort A-triple negative (TN), Cohort B-HR+/HER2-, Cohort C-HER2+. After recovery from definitive surgery, all pts received eribulin mesylate 1.4mg/m2 IV on days 1 and 8 every 21 days for 6 cycles. Cohort C pts also received trastuzumab 6mg/kg IV day 1 every 21 days for a total of 1 yr from start of NAC. Adjuvant hormonal therapy and loco-regional radiotherapy were administered per institutional guidelines. We hypothesized post-operative eribulin would result in a 40% increase over the reported 40% 2 yr DFS for TN, and a 15% increase over the reported 80% 2 yr DFS for HR+/HER2- pts who did not achieve pCR following standard NAC.

Results: 127 pts were enrolled (54, Cohort A; 42, Cohort B; 31, Cohort C). Pts on Cohort C continue with study treatment. Here, we present the results of 95 pts treated on Cohorts A and B. Median age-52 yrs (range, 27-74). 87 pts (92%) had invasive ductal adenocarcinoma, 6 (6%) invasive lobular, 1 (1%) mucinous, and 1 (1 %) unknown; 34 pts (36%) had T3 or T4 tumors and 65 (68%) had N1-2 disease at diagnosis. NAC with anthracyclines was administered to 74 pts (78%), taxanes to 88 (93%), and 72 (76%) received both. 71 pts (75%) had mastectomies, 24 (25%) had breast conserving surgery. Median residual tumor was 17.5 mm (range 0.1 to 80); 60 pts (63%) were LN+. 78 pts (81%) completed the planned 6 cycles of eribulin. Adjuvant radiation was administered in 28 pts (30%). 3 pts discontinued treatment due to toxicity (1 each with G3 neutropenia, G3 nausea, and unknown grade neuropathy). The most common treatment-related G3/4 adverse events were neutropenia [29 pts (31%)] and leukopenia [10 pts (11%)]. 3 pts (3%) had G3/4 febrile neutropenia and 2 pts (2%) had G3/4 neuropathy. Growth factors were administered to 22 pts (24%). There were no treatment-related deaths. With a median follow up of 19.2 and 14.9 months for Cohorts A and B respectively, the 2 yr DFS probabilities calculated from date of surgery were 61.1 % (95% CI-41.2-76.0) for Cohort A; 82.2% (95% CI-60.2-92.7) for Cohort B.

Conclusions: The addition of eribulin is safe and feasible in pts who do not achieve pCR following anthracycline and/or taxane based NAC. At a median follow up of 19.2 months, a statistically significant improvement in the estimated 2 yr DFS was evident in the TN (Cohort A) pts.

Citation Format: Yardley DA, Peacock N, Shroff S, Molthrop, Jr DC, Anz B, Daniel BR, Young RR, Weaver R, Harwin W, Webb CD, Ward P, Shastry M, DeBusk LM, Midha R, Hainsworth JD, Burris III HA. A phase 2 study of eribulin in breast cancer not achieving a pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-12-04.

Abstract P5-14-04: A phase 2 study evaluating orteronel, an inhibitor of androgen biosynthesis, in patients with androgen receptor (AR)-expressing metastatic breast cancer: Interim analysis

Background: The frequency of AR expression varies in the different breast cancer subtypes with 88%, 59%, and 32% expression reported in ER+, HER2+, and triple negative tumors, respectively. AR expression is associated with resistance to endocrine therapy in ER+ breast cancer. Androgen levels frequently increase following treatment with aromatase inhibitors suggesting a role for androgen synthesis inhibitors in ER+ breast cancer. AR signaling and expression are seen in triple negative breast cancer (TNBC), and a distinct AR TNBC subtype can be identified by gene expression profiling. AR expression in TNBC offers a potential therapeutic target. Preclinical and clinical studies demonstrated anti-androgen agent activity in breast cancer cell lines; preliminary clinical data suggests activity in TNBC. Orteronel is a novel, oral, selective, nonsteroidal inhibitor of 17, 20-lyase, a key enzyme in androgen biosynthesis that is being evaluated as endocrine therapy in various hormone-sensitive cancers. In this phase 2 study we are evaluating single agent orteronel in AR+ MBC.

Methods: Pts with AR expressing MBC (≥10% staining by central immunohistochemistry) were eligible. Pts were grouped into 2 cohorts for analysis: Cohort 1-TNBC and Cohort 2-ER+ (HER2 could be +/- in this cohort). Pts must have been previously treated with standard therapy for MBC (1-3 chemotherapy regimens for TNBC, 1-3 hormonal therapies + 1 chemotherapy for ER+ patients, ≥2 HER2-targeted regimens for HER2+ patients). A 6 pt lead-in for safety and tolerability of orteronel in AR+ female MBC pts was followed by open enrollment to either cohort. All pts received 300 mg orteronel PO BID over a 4 week cycle and underwent response assessment every 2 cycles. Treatment was continued until disease progression or unacceptable toxicity. The hypothesized response rate for Cohort 1 was 10% and 13% for Cohort 2. We present the results of a protocol-specified interim analysis of the ER+ MBC pts (Cohort 2).

Results: From 3/2014 to 4/2015, a total of 29 pts were enrolled on cohort 2. Median age was 65 years (range, 39-79); 90% ECOG ≤1; 90% HER2-/10% HER2+; median of 7 prior therapies (range 3-11). 93% had prior chemotherapy. Pts received a median of 2 cycles of orteronel treatment (range 1-4) and 3 pts (10%) are still on treatment. Of the 26 pts (90%) pts that have discontinued, 19 (66%) discontinued due to disease progression, 4 (14%) due to pt decision, 2 (7%) due to adverse event (AE), and 1 (3%) due to non-compliance. The most common treatment-related G 3/4 AEs were increased lipase [3 pts (10%)] and hypertension [2 pts (7%)]. There were no treatment-related SAEs or deaths on study. Three pts (10%) had stable disease as their best response. Further response evaluation is underway.

Conclusions: Orteronel monotherapy was well tolerated but appears to have limited single-agent activity in this heavily pre-treated ER+ MBC pt population. The full results from this interim analysis will be presented.

Citation Format: Yardley DA, Peacock N, Young RR, Silber A, Chung G, Webb CD, Jones SF, Shastry M, Midha R, DeBusk LM, Hainsworth JD, Burris HA. A phase 2 study evaluating orteronel, an inhibitor of androgen biosynthesis, in patients with androgen receptor (AR)-expressing metastatic breast cancer: Interim analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-14-04.

Sorafenib Plus Ixabepilone as First-Line Treatment of Metastatic HER2-Negative Breast Cancer: A Sarah Cannon Research Institute Phase I/II Trial

BACKGROUND

The purposes of the present phase I/II trial were (1) to define tolerable doses of ixabepilone and sorafenib when used in combination and (2) to evaluate the efficacy and toxicity of this combination in the treatment of patients with human epidermal growth factor receptor-negative metastatic breast cancer (MBC).

PATIENTS AND METHODS

The eligible patients had human epidermal growth factor receptor-negative MBC and had not received previous chemotherapy in the metastatic setting. All patients received ixabepilone intravenously on day 1 of each 21-day treatment cycle; sorafenib was administered orally twice daily. Patients in phase II received the maximum doses identified in phase I. The patients were reevaluated after the completion of 3 treatment cycles; treatment continued until disease progression or intolerable toxicity. A total of 67 patients were required in phase II to demonstrate increased median progression-free survival from 4.2 to 6.2 months (90% power, α = 0.05).

RESULTS

Ten patients entered the phase I portion; the maximum tolerated doses were ixabepilone 32 mg/m(2) and sorafenib 400 mg orally twice daily. A total of 76 patients were treated at the phase II dose. The median progression-free survival was 4.8 months (95% confidence interval, 3.5-6.3 months). The overall response rate was 37%. The regimen was difficult to tolerate for many patients; 20 patients discontinued because of toxicity, and dose reductions were frequent. The common toxicities included neutropenia, fatigue, rash, and neuropathy.

CONCLUSION

The combination of ixabepilone and sorafenib was poorly tolerated as first-line treatment of patients with MBC. The activity of the combination was similar to the activity previously reported with single-agent ixabepilone or taxanes. Further development of this combination is not recommended.

Frequency of HER2 mutations and amplification in GI malignancies and ability of pertuzumab to overcome neuregulin1 mediated drug resistance to a HER2 tyrosine kinase inhibitor in colon cancer

630

Background: HER2 amplifications and activating mutations are an emerging drug target in the treatment of colorectal cancer (CRC). Ongoing studies, such as MyPathway (Clinicaltrials.gov NCT02091141), include basket trials of targeted therapies for multiple solid tumor types. The frequency of HER2 mutations in GI cancers and a drug resistance mechanism to the HER2 kinase inhibitor, afatinib, are presented here. Methods: The Foundation Medicine database of 53,126 cases was searched and clinical data from patients with GI tumors enrolled in the HER2 basket of MyPathway was included. Results: 10,358 patients with GI cancers and FoundationOne (FO) testing were identified and compared to the HER2 mutation frequency reported by The Cancer Genome Atlas (TCGA). In MyPathway, 28 GI tumors with HER2 alterations are enrolled: CRC (n = 13, all amplified), liver/biliary (n = 5), pancreatic (n =4), small intestine (n = 3), and esophageal (n = 2). Several CRC patients demonstrated responses to trastuzumab/pertuzumab (reported separately). The HER2 mutant CRC cell lines, CW-2 and CCK-81, are highly sensitive to afatinib (IC50=7-20 nM). Addition of the HER3 ligand, neuregulin1 caused afatinib resistance, but pertuzumab prevented HER3/HER2 activation and reversed this drug resistance. Conclusions: HER2 mutations or amplifications are commonly found in a wide range of GI cancers. Pre-clinical data provide rationale for inclusion of pertuzumab in the treatment strategy for these cancers. The MyPathway Trial is testing this approach. [Table: see text]

Targeted therapy for gastrointestinaI (GI) tumors based on molecular profiles: Early results from MyPathway, an open-label phase IIa basket study in patients with advanced solid tumors

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Background: Next-generation sequencing often reveals potentially actionable molecular alterations; however, data on approved targeted therapies in non-indicated tumors are limited. MyPathway (NCT02091141) evaluates agents targeting the HER2, EGFR, BRAF, or Hedgehog (Hh) pathways in tumors for which these therapies are not currently indicated. Here, we present early response data for patients with GI tumors. Methods: Eligible patients had metastatic tumors with potentially actionable genomic alterations, identified by a CLIA-certified lab, and progression on standard therapy. Based on the identified alteration, patients received standard doses of trastuzumab + pertuzumab (HER2), erlotinib (EGFR), vemurafenib (BRAF), or vismodegib (Hh). Response was evaluated by the investigator using RECIST v1.1. Results: As of Aug 21, 2015, 96 patients had enrolled, 36 of whom (38%) had GI tumors with the following alterations: HER2 (n=28 [22 amplifications, 5 activating mutations, 1 both]), BRAF (n=4), Hh (n=2 [2 PTCH-1 mutations]), and EGFR (n=2). Patients had a median of 4 (range, 1–8) prior lines of therapy. Tumor types and interim best response data are shown below. Among all evaluable patients with GI tumors (n=26), 5 have had a PR to targeted therapy (duration 3–10+ months). Conclusions: Targetable molecular alterations were found in a variety of GI tumors, resulting in clinical benefit from targeted treatments that would not have otherwise been realized. These early results support this molecular testing strategy. Accrual to the trial continues; based on activity observed, the HER2-positive colorectal cancer cohort will be expanded to ≥30 patients. Additional data will be presented at the meeting. Clinical trial information: NCT02091141. [Table: see text]

Poorly differentiated neoplasms of unknown primary site: diagnostic usefulness of a molecular cancer classifier assay

PURPOSE

Definition of the lineage of poorly differentiated neoplasms (PDNs) presenting as cancer of unknown primary site (CUP) is important since many of these tumors are treatment-sensitive. Gene expression profiling and a molecular cancer classifier assay (MCCA) may provide a new method of diagnosis when standard pathologic evaluation and immunohistochemical (IHC) staining is unsuccessful.

PATIENTS AND METHODS

Thirty of 751 CUP patients (4%) seen from 2000-2012 had PDNs without a definitive lineage diagnosed by histology or IHC (median 18 stains, range 9-46). Biopsies from these 30 patients had MCCA (92-gene reverse transcriptase-polymerase chain reaction mRNA) performed. Additional IHC, gene sequencing, fluorescent in situ hybridization for specific genetic alterations, and repeat biopsies were performed to support MCCA diagnoses, and clinical features correlated. Seven patients had MCCA performed initially and received site-specific therapy.

RESULTS

Lineage diagnoses were made by MCCA in 25 of 30 (83 %) patients, including ten carcinomas (three germ cell, two neuroendocrine, five others), eight sarcomas [three peritoneal mesotheliomas, one primitive neuroectodermal tumor (PNET), four others], five melanomas, and two lymphomas. Additional IHC and genetic testing [BRAF, i(12)p] supported the MCCA diagnoses in 11 of 16 tumors. All seven patients (two germ cell, two neuroendocrine, two mesothelioma, one lymphoma) responded to site-specific therapy based on the MCCA diagnosis, and remain alive (five progression-free) from 25+ to 72+ months.

CONCLUSION

The MCCA provided a specific lineage diagnosis and tissue of origin in most patients with PDNs unclassifiable by standard pathologic evaluation. Earlier use of MCCA will expedite diagnosis and direct appropriate first-line therapy, which is potentially curative for several of these tumor types.

Efficacy of octreotide long-acting repeatable in neuroendocrine tumors: RADIANT-2 placebo arm post hoc analysis

Somatostatin analogues (SSA) have demonstrated antiproliferative activity in addition to efficacy for carcinoid symptom control in functional neuroendocrine tumors (NET). A post hoc analysis of the placebo arm of the RAD001 In Advanced Neuroendocrine Tumors-2 (RADIANT-2) study was conducted to assess the efficacy of octreotide long-acting repeatable (LAR) on progression-free survival (PFS) and overall survival (OS) estimated using the Kaplan-Meier method. Out of 213 patients randomized to placebo plus octreotide LAR in RADIANT-2, 196 patients with foregut, midgut, or hindgut NET were considered for present analysis. Of these, 41 patients were SSA-treatment naïve and 155 had received SSA therapy before study entry. For SSA-naïve patients, median PFS by adjudicated central review was 13.6 (95% CI 8.2-22.7) months. For SSA-naïve patients with midgut NET (n=24), median PFS was 22.2 (95% CI 8.3-29.5) months. For patients who had received SSA previously, the median PFS was 11.1 (95% CI 8.4-14.3) months. Among the SSA-pretreated patients who had midgut NET (n=119), the median PFS was 12.0 (95% CI 8.4-19.3) months. Median OS was 35.8 (95% CI 32.5-48.9) months for patients in the placebo plus octreotide LAR arm; 50.6 (36.4 - not reached) months for SSA-naïve patients and 33.5 (95% CI 27.5-44.7) months for those who had received prior SSA. This post hoc analysis of the placebo arm of the large phase 3 RADIANT-2 study provides data on PFS and OS among patients with progressive NET treated with octreotide therapy.

Paclitaxel, bevacizumab, and everolimus/placebo as first-line treatment for patients with metastatic HER2-negative breast cancer: a randomized placebo-controlled phase II trial of the Sarah Cannon Research Institute

Amplified PI3K/Akt/mTOR signaling is common in metastatic breast cancer (MBC). The mTOR inhibitor everolimus improves progression-free survival (PFS) when added to steroidal aromatase inhibitor therapy. This randomized phase II trial compares the efficacy of paclitaxel/bevacizumab/everolimus and paclitaxel/bevacizumab/placebo as first-line treatment for MBC. Patients with untreated HER2-negative MBC were randomized (1:1) to receive 28-day cycles of paclitaxel 90 mg/m(2) IV (days 1, 8, and 15) and bevacizumab 10 mg/kg IV (days 1, 15) with either everolimus 10 mg (Arm 1) or placebo (Arm 2) daily. Treatment continued (evaluation every 8 weeks) until progression or unacceptable toxicity. Treatment of 110 patients allowed detection of an improvement in median PFS from 11 to 16 months (70 % power, α = 0.10). Between August 2009 and June 2011, 113 patients (median age 58 years; 88 % ER or PR positive) were randomized (Arm 1, 56; Arm 2, 57). Patients in both arms received a median of six treatment cycles. Median PFS (95 % CI) was 9.1 months (6.8-18.8) for Arm 1, and 7.1 months (5.6-10.8) for Arm 2 (p = 0.89). Comparisons of other efficacy endpoints were also similar in the two treatment arms. Patients receiving everolimus had more anemia, stomatitis, diarrhea, rash, and arthralgia/myalgia, although the overall incidence of severe (grade 3/4) toxicity was similar. The addition of everolimus did not improve the efficacy of weekly paclitaxel/bevacizumab as first-line treatment for patients with HER2-negative MBC. These results contrast with the demonstrated efficacy of adding everolimus to either hormonal or HER2-targeted therapy in previously treated patients.

Disease characteristics, treatment patterns, and outcomes of follicular lymphoma in patients 40 years of age and younger: an analysis from the National Lymphocare Study†

BACKGROUND

Follicular lymphoma (FL) is the most common indolent non-Hodgkin lymphoma, with median age at diagnosis in the seventh decade. FL in young adults (YAs), defined as diagnosis at ≤40 years, is uncommon. No standard approaches exist guiding the treatment of YA FL, and little is known about their disease characteristics and outcomes. To gain further insights into YA FL, we analyzed the National LymphoCare Study (NLCS) to describe characteristics, initial treatments, and outcomes in this population versus patients aged >40 years.

PATIENTS AND METHODS

Using the NLCS database, we stratified FL patients by age: 18-40 (YA), 41-60, 61-70, 71-80, and >80 years. Survival probability was estimated using Kaplan-Meier methodology. We examined associations between age and survival using hazard ratios and 95% confidence intervals (CIs) from multivariable Cox models.

RESULTS

Of 2652 eligible FL patients in the NLCS, 164 (6%) were YAs. Of YA patients, 69% had advanced disease, 80% had low-grade histology, and 50% had good-risk disease according to the Follicular Lymphoma International Prognostic Index (FLIPI). Nineteen percent underwent observation, 12% received rituximab monotherapy, and 46% received chemoimmunotherapy [in 59% of these: R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone)]. With a median follow-up of 8 years, overall survival (OS) at 2, 5, and 8 years was 98% (95% CI 93-99), 94% (95% CI 89-97), and 90% (95% CI 83-94), respectively. Median progression-free survival (PFS) was 7.3 years (95% CI 5.6-not reached).

CONCLUSIONS

In one of the largest cohorts of YA FL patients treated in the rituximab era, disease characteristics and outcomes were similar to patients aged 41-60 years, with favorable OS and PFS in YAs. Longer-term outcomes and YA-specific survivorship concerns should be considered when defining management. These data may not support the need for more aggressive therapies in YA FL.

CLINICAL TRIAL NUMBER

Roche/Genentech ML01377 (U2963n).

Phase I/II trial of neoadjuvant sunitinib administered with weekly paclitaxel/carboplatin in patients with locally advanced triple-negative breast cancer

The purpose of the study is to evaluate the feasibility and efficacy of adding sunitinib to paclitaxel/carboplatin in the neoadjuvant therapy of patients with triple-negative breast cancer (TNBC). Patients had histologically proven, previously untreated, triple-negative adenocarcinoma, with disease limited to the breast and axilla (clinical T1-T3, N0-N2, M0; T1N1M0 excluded). Following determination of the maximum tolerated doses in the phase I portion, patients in the phase II study received paclitaxel 70 mg/m(2) IV days 1, 8, and 15; carboplatin AUC 5.0 IV day 1; sunitinib 25 mg orally daily; treatment was administered for six 28-day cycles followed by definitive surgery. Sunitinib was resumed postoperatively to complete a 52-week course. Pathologic complete response (pCR) rate was the primary endpoint. Fifty-four patients enrolled; 41 received treatment in the phase II study. Sixteen patients (39 %) were able to complete six cycles of neoadjuvant therapy; 18 additional patients had surgery after completing 2-5 cycles of treatment. The pCR rate in these 34 evaluable patients was 35 %. The toxicity of the regimen was considerable, with myelosuppression resulting in numerous dose reductions and/or omissions of paclitaxel and carboplatin. Eleven patients (27 %) discontinued sunitinib during neoadjuvant therapy, and six patients (14 %) completed 52 weeks of single-agent sunitinib. In the neoadjuvant treatment of patients with TNBC, the combination of paclitaxel, carboplatin, and sunitinib was difficult to administer, and produced a pCR rate comparable to other less toxic regimens. This combination is not recommended for further evaluation. At present, sunitinib has no defined role in the treatment of breast cancer.