Clinical characteristics and genetic testing outcome of suspected hereditary peripheral nerve sheath tumours in a tertiary cancer institution in Singapore

Background

Peripheral Nerve Sheath Tumors (PNST) are a diverse group of mostly benign tumours uncommon in the general population. About 5–10% of PNSTs are hereditary, predominantly arising from germline variants in NF1, NF2, SMARCB1, or LZTR1 gene.

Methods

We reviewed the clinical characteristics and genetic testing results of patients referred to the NCIS Adult Cancer Genetics Clinic for suspected hereditary PNST.

Results

3,001 patients suspected to have various hereditary cancer syndromes were evaluated between year 2000 to March 2021. 13 (0.4%) were clinically diagnosed to have hereditary PNSTs. The majority were male (54%), with a median age at presentation to the genetics clinic of 29 years (range 19–48). 11/13 (85%) patients had multiple PNSTs, 12/13 (92%) had young onset PNSTs, 5/13 (38.5%) had personal and family history of PNST. 11/13 patients (85%) had clinical features of neurofibromatosis type 1 (NF1) including one patient who also fulfilled clinical criteria of neurofibromatosis type 2 (NF2); 2/13 (14%) had multiple schwannomas. Four patients underwent multi-gene panel testing, including one patient with clinical NF1, one patient who met both clinical NF1 and NF2 criteria, and two patients with multiple schwannomas. The patient with clinical features of NF1 was heterozygous for a pathogenic c. 2033dup variant in the NF1 gene. The patient with both NF1/NF2 features was heterozygous for a novel c.732 T > A nonsense variant in the NF2 gene. The two patients with multiple schwannomas were heterozygous for a pathogenic/likely pathogenic variant in the LZTR1 gene and are the first LZTR1-positive schwannomatosis patients reported in Asia.

Conclusion

Hereditary PNSTs are rare referrals to an adult cancer genetics clinic. NF1 is the most common PNST seen. LZTR1 variants may be the underlying cause in Asian patients with multiple schwannomatosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13053-022-00230-4.

A phase II, single-arm, open label, Simon two-stage study of pembrolizumab in patients with metastatic HER2-negative breast cancer: Evaluation of impact of germline variants in APOBEC3B (AUROR)

1026

Background: A germline deletion in the APOBEC3B cytosine deaminase gene [A3Bdel] occurs more frequently in Asian women (45% heterozygous deletion (hetD) and 15% homozygous deletion (homD)) compared to in Caucasian women (15% hetD and 4% homD). Carriers are more likely to develop breast cancer, and cancers in carriers are more likely to have a hypermutator phenotype (with C > T transitions) and to be immune-enriched. In this clinical trial, we aim to evaluate whether the immune activation increases response to checkpoint immunotherapy. Methods: In this open label, single arm Phase II study of single agent pembrolizumab in metastatic HER2-receptor negative breast cancer patients with germline deletion in A3B, 40 evaluable subjects who have received > = 1 but < = 3 lines of therapy in a metastatic setting will be enrolled and given pembrolizumab 200 mg intravenously (IV) every 3 weeks (Q3W) for up to 35 administrations (2 years), with Objective Response Rate (ORR) using RECIST 1.1 as the primary study endpoint. The study applies a Simon two-stage design, where if at least 3 out of 22 evaluable patients achieve CR/PR in stage I, the study will proceed to stage II. Results: To date, 84 breast cancer patients were screened for germline A3Bdel, of whom 46 (54.8%) were heterozygous carriers and 12 (14.3%) were homozygous carriers. The study enrolled 22 female A3Bdel carriers with a median age of 59.4 years (range: 32.1, 82.9 years) between September 2020 and September 2021 for stage I analysis. On average, patients received 2 prior lines of chemotherapy in a metastatic setting [6 with 1, 8 with 2 and 8 with 3 lines of prior chemotherapy]. Complete response (CR) was observed in one patient, while partial response (PR) was observed in 4 patients, with an ORR of 22.7% (5 over 22 subjects) in stage I, meeting the pre-defined criteria to proceed to stage II. Notably, the patient with complete response had received 2 prior lines of chemotherapy, whereas of the patients with partial response, 1 had received 1 prior line and 3 had received 3 prior lines of chemotherapy in a metastatic setting. As the observed ORR was greater than the value of r1 (13.6%), the study has met the statistical criteria to proceed to the stage II enrolment with an additional 18 patients required to complete the entire study. Conclusions: Single agent pembrolizumab demonstrates promising efficacy in germline A3Bdel carriers, who constitute almost two-thirds of Asian patients. Clinical trial information: NCT03989089.

A multicenter phase II randomized trial of durvalumab (D) versus physician’s choice chemotherapy (PCC) in patients (pts) with recurrent ovarian clear cell adenocarcinoma (MOCCA/APGOT-OV2/GCGS-OV3)

5565

Background: The optimal treatment of recurrent ovarian clear cell carcinoma (rOCCC) remains unknown. Prior data suggests rOCCC is a chemo-resistant disease that may respond to programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint inhibition (ICI). We aimed to determine the efficacy of D versus PCC in pts with rOCCC. Methods: In this multicentre, open-label, randomised phase 2 trial, 9 academic centres across Singapore, South Korea and Australia, enrolled rOCCC (determined histologically) and Eastern Cooperative Oncology Group performance status (PS) 0-2 pts, who had recurred after prior platinum-based chemotherapy and had not received more than 4 prior lines of systemic therapy, nor prior ICI therapy. Eligible pts were randomly assigned (2:1), using dynamic block randomization with block size of 6, and stratification by ECOG PS, to receive D (1500mg on day 1, in 28-day cycles) or PCC until disease progression (PD), intolerable toxicity or withdrawal of consent. Pts with PD on PCC were allowed to crossover to D. The primary endpoint was investigator-assessed progression-free survival (PFS) by RECIST version 1.1 and analyses included pts who had commenced at least 1 cycle of study treatment. Results: Between 7 Nov 2017 and 17 Feb 2020, 57 pts were assessed for eligibility, of whom 47 (PS 0-1) were randomly assigned to treatment with D (31 pts) or PCC (16 pts). At the data cut-off date (10 Jan 2022), the median follow-up was 83.0 weeks (IQR: 54.1—97.0) in the PCC group and 107.0 weeks (IQR: 82.7—116.4) in the D group. Median PFS was 7.4 weeks (IQR: 6.0—16.0) in the D group and 14.0 (IQR: 7.0—28.6) in the PCC group (HR 1.5 [95% CI 0.8-2.8], log-rank p = 0.89). The objective response rate (ORR) was 10.7% in pts randomised to D and 18.8% in the PCC group (p = 0.884). Clinical benefit rate (CR/PR/SD for ≥16weeks) was similar for PCC (37.5%) and D (32.1%) (p = 0.756). 9 pts on PCC crossed over to receive D, with 2 of the 8 evaluable pts achieving partial response (PR). When crossover D pts were included, ORR to D was 13.9% (5/36) with a clinical benefit rate of 30.6% (11/36). Median duration of response was 44 weeks for the 3 PCC responders (PR to gemcitabine 24.9wks, PR to liposomal doxorubicin 65.7wks, CR to carboplatin/liposomal doxorubicin 44wks), and 18 weeks (range 2.1-45.3) for the 5 responders to D. Frequency of adverse events (AEs) across all grades was 68.8% for PCC and 38.7% for D. Grade 3/4 AEs were observed in 37.5% of PCC pts and 9.7% of D pts. Conclusions: No significant differences in PFS, ORR or clinical benefit rate were observed between D and PCC treatment in rOCCC. Treatment with D was associated with less grade 3-4 adverse events. Correlative translational analyses to elucidate predictive biomarkers of response and resistance are ongoing. Clinical trial information: NCT03405454.

Immunohistochemistry study of tumor vascular normalization and anti-angiogenic effects of sunitinib versus bevacizumab prior to dose-dense doxorubicin/cyclophosphamide chemotherapy in HER2-negative breast cancer

Purpose

Tumor angiogenesis controlled predominantly by vascular endothelial growth factor and its receptor (VEGF-VEGFR) interaction plays a key role in the growth and propagation of cancer cells. However, the newly formed network of blood vessels is disorganized and leaky. Pre-treatment with anti-angiogenic agents can “normalize” the tumor vasculature allowing effective intra-tumoral delivery of standard chemotherapy. Immunohistochemistry (IHC) analysis was applied to investigate and compare the vascular normalization and anti-angiogenic effects of two commonly used anti-angiogenic agents, Sunitinib and Bevacizumab, administered prior to chemotherapy in HER2-negative breast cancer patients.

Methods

This prospective clinical trial enrolled 38 patients into a sunitinib cohort and 24 into a bevacizumab cohort. All received 4 cycles of doxorubicin/cyclophosphamide chemotherapy and pre-treatment with either sunitinib or bevacizumab. Tumor biopsies were obtained at baseline, after cycle 1 (C1) and cycle 4 (C4) of chemotherapy. IHC was performed to assess the tumor vascular normalization index (VNI), lymphatic vessel density (LVD), Ki67 proliferation index and expression of tumor VEGFR2.

Results

In comparison to Bevacizumab, Sunitinib led to a significant increase in VNI post-C1 and C4 (p < 0.001 and 0.001) along with decrease in LVD post-C1 (p = 0.017). Both drugs when combined with chemotherapy resulted in significant decline in tumor proliferation after C1 and C4 (baseline vs post-C4 Ki67 index p = 0.006 for Sunitinib vs p = 0.021 for Bevacizumab). Bevacizumab resulted in a significant decrease in VEGFR2 expression post-C1 (p = 0.004).

Conclusion

Sunitinib, in comparison to Bevacizumab showed a greater effect on tumor vessel modulation and lymphangiogenesis suggesting that its administration prior to chemotherapy might result in improved drug delivery.

Trial registry

ClinicalTrials.gov: NCT02790580 (first posted June 6, 2016).

Infiltrative pattern of metastatic invasive lobular breast carcinoma in the abdomen: a pictorial review

Invasive lobular carcinoma (ILC) has a greater tendency to metastasize to the peritoneum, retroperitoneum, and gastrointestinal (GI) tract as compared to invasive carcinoma of no special type (NST). Like primary ILC in the breast, ILC metastases are frequently infiltrative and hypometabolic, rather than mass forming and hypermetabolic in nature. This renders them difficult to detect on conventional and metabolic imaging studies. As a result, intra-abdominal ILC metastases are often detected late, with patients presenting with clinical complications such as liver failure, hydronephrosis, or bowel obstruction. In patients with known history of ILC, certain imaging features are very suggestive of infiltrative metastatic ILC. These include retroperitoneal or peritoneal nodularity and linitis plastica appearance of the bowel. Recognition of linitis plastica on imaging should prompt deep or repeat biopsies. In this pictorial review, the authors aim to familiarize readers with imaging features and pitfalls for evaluation of intra-abdominal metastatic ILC. Awareness of these will allow the radiologist to assess these patients with a high index of suspicion and aid detection of metastatic disease. Also, this can direct histopathology and immunohistochemical staining to obtain the correct diagnosis in suspected metastatic disease.

Neratinib + capecitabine sustains health-related quality of life in patients with HER2-positive metastatic breast cancer and ≥ 2 prior HER2-directed regimens

PURPOSE

To characterize health-related quality of life (HRQoL) in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) from the NALA phase 3 study.

METHODS

In NALA (NCT01808573), patients were randomized 1:1 to neratinib + capecitabine (N + C) or lapatinib + capecitabine (L + C). HRQoL was assessed using seven prespecified scores from the European Organisation for Research and Treatment of Cancer Quality Of Life Questionnaire core module (QLQ-C30) and breast cancer-specific questionnaire (QLQ-BR23) at baseline and every 6 weeks. Descriptive statistics summarized scores over time, mixed models evaluated differences between treatment arms, and Kaplan-Meier methods were used to assess time to deterioration in HRQoL scores of ≥ 10 points.

RESULTS

Of the 621 patients randomized in NALA, patients were included in the HRQoL analysis if they completed baseline and at least one follow-up questionnaire. The summary, global health status, physical functioning, fatigue, constipation, and systemic therapy side effects scores were stable over time with no persistent differences between treatment groups. There were no differences in time to deterioration (TTD) for the QLQ-C30 summary score between treatment arms; the hazard ratio (HR) for N + C vs. L + C was 0.94 (95% CI 0.63-1.40). Only the diarrhea score worsened significantly more in the N + C arm as compared to the L + C arm, and this remained over time (HR for TTD for N + C vs. L + C was 1.71 [95% CI 1.32-2.23]).

CONCLUSION

In NALA, patients treated with N + C maintained their global HRQoL over time, despite a worsening of the diarrhea-related scores. These results may help guide optimal treatment selection for HER2-positive MBC.

The impact of COVID-19 on and recommendations for breast cancer care: the Singapore experience

The ensuing COVID-19 pandemic poses unprecedented and daunting challenges to the routine delivery of oncological and supportive care to patients with breast cancer. Considerations include the infective risk of patients who are inherently immunosuppressed from their malignancy and therapies, long-term oncological outcomes from the treatment decisions undertaken during this extraordinary period, and diverted healthcare resources to support a coordinated whole-of-society outbreak response. In this review, we chronicle the repercussions of the COVID-19 outbreak on breast cancer management in Singapore and describe our approach to triaging and prioritising care of breast tumours. We further propose adaptations to established clinical processes and practices across the different specialties involved in breast oncology, with references to the relevant evidence base or expert consensus guidelines. These recommendations have been developed within the unique context of Singapore's public healthcare sector. They can serve as a resource to guide breast cancer management for future contingencies in this city-state, while certain elements therein may be extrapolatable to other medical systems during this global public health emergency.

Molecular profiling of metastatic breast cancer (MBC) and target-based therapeutic matching in an Asian tertiary phase I oncology unit

3561

Background: Somatic profiling of MBC has highlighted actionable mutations and driven trials of matched targeted therapy (tx). Previous phase I studies have reported improved outcomes following matched therapies with tumour molecular profiles. Here, we review next generation sequencing (NGS) and treatment outcomes of Asian MBC patients (pts) in the phase I unit of a tertiary centre. Methods: Pts with MBC referred to a phase I unit underwent NGS (n = 152). Tumour tissue was sequenced via the amplicon based Ion Ampliseq Cancer (IAC) v2 (50 genes) platform from 2014-2017 prior to institutional change to Foundation Medicine 1 (FM1) (324 genes) 2017-2019. Patients were counselled on findings and enrolled onto matched therapeutic trials where available. Results: NGS was successfully performed in 107 pts (IAC 46%, FM1 54%) of which tumour subtypes include hormone receptor positive 63%, triple negative breast cancer (TNBC) 28% and Her2 positive 19%. Median lines of prior tx for MBC was 4 (range 0-12). 89% had prior chemotherapy (CT), 57% prior endocrine therapy (ET). 72/107 (67%) sequenced patients had further treatment and 18 (25%) were matched to tx based on NGS findings (15 clinical trial, 3 off trial). Matching rates on both NGS platforms were similar (IAC 22% vs FM1 28%). Mutated pathways with potential matched tx included PIK3CA/AKT/PTEN (52%), DNA damage response (DRR) (15%), and FGFR (11%) pathways. PIK3 mutations were seen in 43% and associated with higher number of metastatic sites (p = 0.03); most prevalent aberrations were PIK3CA H1047R (41%) and PIK3CA E542K (13%). Matched cases were more heavily pretreated (mean lines of prior tx 5.3 matched vs 3.7, unmatched p = 0.05), and showed a median progression free survival (mPFS) of 24 weeks [w] and clinical benefit rate (complete/partial response or stable disease ≥ 12 weeks) of 53% on matched tx. Comparison by NGS platform showed improved mPFS for matched vs unmatched pts sequenced on FM1 vs IAC (FM1: 26 vs 19w, HR = 0.76 [95% CI: 0.3-1.9]; IAC: 8 vs 12w; HR = 1.21 [95% CI: 0.5-2.8]). Interestingly, 1 pt with SMARCB mutation, reportedly associated with the FGFR pathway, had a PFS of 70w on tx with a pan-FGFR inhibitor after progressing on 3 prior lines of tx (ET and CT). Conclusions: Molecular profiling of MBC in a phase I unit led to matched tx in 25% of cases. Matched pts showed encouraging mPFS with a suggestion of benefit in those matched after sequencing on a broader gene panel (FM1).

Clinical efficacy and molecular effects of lenvatinib (Len) and letrozole (Let) in hormone receptor-positive (HR+) metastatic breast cancer (MBC)

1019

Background: Preclinical studies show cross talk between RET and estrogen receptor, with at least additive treatment (Tx) effect of Len, a RET inhibitor, with Let. Our previous work concluded a recommended phase 2 dose (RP2D) of Len 14mg daily and Let 2.5mg daily (Lim, ASCO 2019). We present efficacy data from dose escalation and expansion cohorts. Methods: Safety, tolerability and efficacy data of MBC patients in both dose escalation (Len dose level 1 [DL]:20mg, DL -1:16mg and DL -2:14mg) and expansion (Len 14mg) cohort of this phase Ib/II study of combination Len+Let study was analysed. Patients were treated with single-agent Len for 2 weeks, followed by Len+Let until disease progression (PD). Serial tumor biopsies at baseline, after Len alone, 4 weeks post Len+Let, and upon PD, were sequenced for 440 genes with the ACTOnco+ platform. Results: A total of 33 pts (DL1 6pts, DL-1 6pts, DL-2 + expansion 21pts) with median 5 lines of prior Tx (range 0-11) were enrolled; 87.9%, 75.8%, and 75.8% had prior endocrine therapy (ET), ET+CDK4/6 inhibitor (i), and chemotherapy (CT) respectively. Objective response rate (ORR), disease control rate (DCR) ≥6 months (m), median duration of response (DOR), and percentage progression-free (PPF) at 12m were 33.3%, 45.5%, 11.5m (range 6.3-22.4), and 27.2% respectively. Among patients who previously progressed on CDK4/6i (n = 25), ORR, DCR ≥6m, median DOR, and PPF at 12m were 24.0%, 40.0%, 13.7m (range 6.3-18.2), and 12.0% respectively. Of note, 3/25 (12%) patients had durable response to Len+Let lasting ≥12m, despite having only modest PFS on ET+CDK4/6i (3, 7, and 12 months respectively). Most frequent all-grade toxicities (tox) were HTN (n = 15, G3:15), hypothyroidism (n = 20, G3:0) and fatigue (n = 13, G3:2), with no G4/5 tox. No new toxicity signals were observed compared to dose escalation phase. Pre-treatment tumor molecular profiling showed responders to be more likely to harbor NEFH, USH2A and PTCH1 mutations, while non-responders were more likely to carry PIK3R1, APC and PALB2 mutations. Sequencing of serial biopsies showed downregulation of BRD4, PTCH1, KIT, NTRK1 and CREBBP after Len treatment. Conclusions: Len+Let showed significant anti-tumor activity with meaningful duration of response, even in pts who failed prior CT or ET+CDK4/6i. The results support further investigation in randomized studies. Tumor profiling identified mutations associated with response and insights on molecular effects of lenvatinib. Clinical trial information: NCT02562118 .

Concomitant limb cryocompression and scalp cooling to reduce paclitaxel-induced neuropathy and alopecia

e24157

Background: Scalp cooling is an FDA approved method to mitigate chemotherapy-induced alopecia (CIA) caused by paclitaxel. Chemotherapy-induced peripheral neuropathy (CIPN) is a dose limiting toxicity of paclitaxel. Several recent randomized studies have suggested limb hypothermia as a mechanism to ameliorate paclitaxel-induced neuropathy. The safety, tolerability and feasibility of concomitant limb hypothermia and scalp cooling to prevent these two common adverse effects of paclitaxel has not been previously studied. Methods: A proof-of-concept study was conducted in breast cancer patients receiving weekly paclitaxel chemotherapy. Each subject underwent concomitant scalp and four-limb cryocompression with each chemotherapy infusion (3 hours) for a maximum of 12 cycles. Limb cryocompression was administered at cyclic pressure (5-15 mmHg) and temperatures starting at 11°C (established as lowest tolerable temperature in a separate healthy volunteer study) and adjusted according to patient tolerability. Skin surface temperature and tolerance scores were recorded. CIPN was assessed via EORTC Quality of Life Questionnaire-CIPN before (QOLpre), after completion (QOLpost) and 3-months post chemotherapy (QOL3m). Results: Fifteen patients enrolled in the study, of which 14 completed all 12 cycles of concomitant scalp cooling and limb cryocompression during chemotherapy without any side effects barring transient erythema over the limbs. None had intolerance to scalp cooling. Eight patients safely tolerated 12 cycles of cryocompression at 11°C. Of the remaining, 6 completed all 12 cycles at device temperatures ranging from 14-25°C. One patient withdrew at the 6th cycle, finding 25°C intolerable. Median QOLpre was 19 (range 17-19), QOLpost 20 (18-29) (p = 0.04, Wilcoxon signed-rank) and QOL3m was 19 (18-21) (vs QOLpre; p = 1). QOL showed no significant differences from pre-chemotherapy to 3 months post-chemotherapy suggesting preservation of nerve function. Conclusions: Delivery of concomitant scalp cooling and limb cryocompression is feasible, safe and generally well-tolerated. Future limb hypothermia trials should not preclude patients from undergoing scalp-cooling concomitantly to reduce CIA. Clinical trial information: NCT03248193 .

CONTESSA TRIO: A multinational, multicenter, phase (P) II study of tesetaxel (T) plus three different PD-(L)1 inhibitors in patients (Pts) with metastatic triple-negative breast cancer (TNBC) and tesetaxel monotherapy in elderly pts with HER2-metastatic breast cancer (MBC)

TPS1111

Background: Chemotherapy treatments with robust efficacy that preserve quality of life are needed. T is a novel, oral taxane that has potential advantages over currently available taxanes, including: oral administration with a low pill burden and once every 3 week (Q3W) dosing; no observed hypersensitivity reactions; preclinical evidence of central nervous system (CNS) penetration; and improved activity against chemotherapy-resistant tumors. More than 600 pts have been treated with T in clinical studies. T had robust monotherapy activity in a P2 study in 38 pts with HER2-, HR+ MBC, with a confirmed objective response rate (ORR) per RECIST 1.1 of 45%. Methods: CONTESSA TRIO is a 2-cohort, multinational, multicenter, P2 study. In Cohort 1, 90 pts (potential expansion to up to 150 pts) with metastatic TNBC who have not received prior chemotherapy for advanced disease will be randomized 1:1:1 to receive T at 27 mg/m2 Q3W plus either: (1) nivolumab at 360 mg Q3W; (2) pembrolizumab at 200 mg Q3W; or (3) atezolizumab at 1,200 mg Q3W. Nivolumab and pembrolizumab (PD-1 inhibitors) and atezolizumab (a PD-L1 inhibitor) are approved for the treatment of multiple types of cancer; atezolizumab, in combination with nab-paclitaxel, was recently approved in the US for the treatment of metastatic TNBC. The dual primary endpoints for Cohort 1 are ORR and progression-free survival (PFS). A sample size of 30 pts in each PD-(L)1 inhibitor treatment group has approximately 70% power to detect an ORR difference of ≥ 35% between the treatment group with the highest ORR and the treatment group with the lowest ORR. Secondary endpoints include duration of response (DoR) and overall survival (OS). Efficacy results for each of the 3 PD-(L)1 inhibitor combinations will be assessed for correlation with the results of each of the 3 approved PD-L1 diagnostic assays. CONTESSA TRIO is the first randomized clinical study to compare 3 approved PD-(L)1 inhibitors. In Cohort 2, 40 elderly pts (potential expansion to up to 60 pts) with HER2- MBC who have not received prior chemotherapy for advanced disease will receive T monotherapy at 27 mg/m2 Q3W. The primary endpoint for Cohort 2 is ORR. A sample size of 40 will allow the ORR to be estimated with a maximum standard error of < 8%. Secondary endpoints include PFS, DoR and OS. Pts with CNS metastases are eligible for both cohorts. The study was initiated in March 2019. Clinical trial information: NCT03952325 .

Abstract OT1-08-08: CONTESSA TRIO: A multinational, multicenter, phase 2 study of tesetaxel plus 3 different PD-(L)1 inhibitors in patients with metastatic triple-negative breast cancer (TNBC) and tesetaxel monotherapy in elderly patients with HER2- metastatic breast cancer (MBC)

Background: Chemotherapy treatments with robust efficacy that preserve quality of life are needed. Tesetaxel is a novel, oral taxane that has potential advantages over currently available taxanes, including: oral administration with a low pill burden and once every 3 week (Q3W) dosing; no observed hypersensitivity reactions; preclinical evidence of central nervous system (CNS) penetration; and improved activity against chemotherapy-resistant tumors. More than 600 patients have been treated with tesetaxel in clinical studies. Tesetaxel had robust monotherapy activity in a Phase 2 study in 38 patients with HER2-, HR+ MBC, with a confirmed objective response rate (ORR) per RECIST 1.1 of 45%. CONTESSA TRIO investigates tesetaxel plus 3 different PD-(L)1 inhibitors in patients with TNBC and tesetaxel monotherapy in elderly patients with HER2- MBC.

Trial design: CONTESSA TRIO is a 2-cohort, multinational, multicenter, Phase 2 study.

In Cohort 1, 90 patients (with potential expansion to up to 150 patients) with metastatic TNBC who have not received prior chemotherapy for advanced disease will be randomized 1:1:1 to receive tesetaxel at 27 mg/m2 Q3W plus either: (1) nivolumab at 360 mg Q3W; (2) pembrolizumab at 200 mg Q3W; or (3) atezolizumab at 1,200 mg Q3W. Nivolumab and pembrolizumab (PD-1 inhibitors) and atezolizumab (a PD-L1 inhibitor) are approved for the treatment of multiple types of cancer; atezolizumab, in combination with nab-paclitaxel, was recently approved in the U.S. for the treatment of metastatic TNBC. The dual primary endpoints for Cohort 1 are ORR and progression-free survival (PFS). A sample size of 30 patients in each PD-(L)1 inhibitor treatment group has approximately 70% power to detect an ORR difference of 35% or greater between the treatment group with the highest ORR and the treatment group with the lowest ORR. An increase in the sample size to 50 patients in each treatment group will increase the power to approximately 85%. Secondary endpoints include duration of response (DoR) and overall survival (OS). Efficacy results for each of the 3 PD-(L)1 inhibitor combinations will be assessed for correlation with the results of each of the 3 approved PD-L1 diagnostic assays. CONTESSA TRIO is the first randomized clinical study to compare 3 approved PD-(L)1 inhibitors.

In Cohort 2, 40 elderly patients (with potential expansion to up to 60 patients) with HER2- MBC who have not received prior chemotherapy for advanced disease will receive tesetaxel monotherapy at 27 mg/m2 Q3W. The primary endpoint for Cohort 2 is ORR. A sample size of 40 will allow the ORR to be estimated with a maximum standard error of &lt; 8%. An increase in the sample size to 60 patients will decrease the maximum standard error to &lt; 6.5%. Secondary endpoints include PFS, DoR and OS.

Patients with CNS metastases are eligible for both cohorts. The Study was initiated in March 2019. For further information on this trial, email joconnell@odonate.com or visit clinicaltrials.gov (NCT03952325).

Citation Format: Sara Tolaney, Joanne Blum, Igor Bondarenko, Arlene Chan, Noshir DaCosta, Yin-Hsun Feng, Yann Izarzugaza, Sung-Bae Kim, Mei-Ching Liu, Maria Eva Peréz Lopéz, Mafalda Oliveira, Samuel Guan Wei Ow, Michel Pavic, Hope Rugo, Lee Schwartzberg, Agostina Stradella, Stew Kroll, Joseph O'Connell, Thomas Wei, Elizabeth Mittendorf. CONTESSA TRIO: A multinational, multicenter, phase 2 study of tesetaxel plus 3 different PD-(L)1 inhibitors in patients with metastatic triple-negative breast cancer (TNBC) and tesetaxel monotherapy in elderly patients with HER2- metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-08-08.

Using next-generation sequencing (NGS) platform to diagnose pathogenic germline BRCA1/2 mutations from archival tumor specimens

OBJECTIVE

Clinical genetic testing to diagnose germline mutations often requires blood sample or saliva smear from a cancer-affected individual. This rules out testing in families when cancer-affected individuals are deceased. We explored the use of a next-generation sequencing (NGS) platform to diagnose germline pathogenic mutations from tumors.

METHODS

Archival tumors (ovarian = 26, breast = 25, others = 9) were retrieved from 60 cancer patients who have undergone multi-gene panel blood testing. Genomic DNA was extracted and sequenced for BRCA1/2 using a NGS platform. 41/60 specimens were sequenced for 5 other genes (APC, ATM, PALB2, PTEN, TP53). Tumor testing and results interpretation were performed blinded to the blood test result.

RESULTS

All 38 patients with no BRCA1/2 mutations on blood testing were correctly tested negative on tumor. Tumor testing correctly diagnosed BRCA1/2 pathogenic mutations in 15/22 (68%) patients while in 7/22 (32%) patients, the mutation was either detected but incorrectly classified as VUS (n = 3) or not detected at all (n = 4). Overall concordance rate for tumor and blood testing for BRCA1/2 mutations was 88%, with 0% false positive and 32% false negative rate for pathogenic mutations. Tumor testing correctly diagnosed 1/2 pathogenic germline ATM mutation, 1/1 pathogenic germline PALB2 mutation and 2/2 pathogenic germline TP53 mutations. False positive germline mutations were diagnosed in 4 genes at a rate of 2.4%-10.3% (APC = 2.4%, PALB2 = 2.4%, PTEN = 4.9%, TP53 = 10.3%).

CONCLUSION

Tumor testing for BRCA1/2 germline mutations using an NGS platform is fairly reliable with no false positive findings, and correctly diagnosed more than two-thirds of pathogenic germline BRCA1/2 mutations. However, it is not reliable to diagnose pathogenic germline mutations in genes frequently mutated in sporadic cancers, such as PTEN and TP53.

A phase Ib/II trial of lenvatinib (len) and letrozole (let) incorporating pharmacodynamics studies in postmenopausal women with hormone receptor positive (HR+) locally advanced/metastatic breast cancer (LABC/MBC)

1045

Background: Endocrine blockade (EB) is standard of care for patients (pts) with HR+ LABC/MBC. RET over-expression (RET+) occurs in up to 75% of HR+ breast cancers and is a postulated mechanism of endocrine resistance. Preclinical studies show cross talk between RET and estrogen receptor, and at least additive treatment (Tx) effect of Len+EB. Methods: We performed a phase Ib trial (3+3 dose escalation) to study safety, tolerability, pharmacodynamics and efficacy of Len+Let. Both drugs were given as continuous daily dosing with 2 weeks (wks) of Len alone, followed by Len+Let for 12 wks then surgery (LABC), or till disease progression (PD) (MBC). Serial tumor biopsies (n = 15) were done at baseline, after Len alone, 4 wks post Len+Let, and at surgery [LABC] / upon PD [MBC]. Results: 16 pts were treated (4 LABC, 12 MBC); Among MBC pts, median lines of prior Tx was 3 (range 0-10); 84.6%, 66.7%, and 58.3% had prior EB, EB+CDK4/6 inhibitor (i), and chemotherapy (CT) respectively. At dose level (DL) 1, 2/4 pts had dose-limiting toxicities (DLT). There was no DLT at DL-1, but 6/6 pts needed dose reductions (DR), with 4/6 DR within 6 wks of Len+Let (3 G3 hypertension [HTN], 1 G3 wound pain), deeming DL-1 intolerable. At DL-2, 0/6 pts had DLT; this was declared recommended phase 2 dose (RP2D). Most frequent G3 toxicities (tox) were HTN (6/16), proteinuria (2/16) and palmar-plantar erythrodysesthesia (PPE) (2/16), with no G4/5 tox. Len+Let was active with 93.8% overall disease control rate (DCR) (50.0% partial response [PR], 43.8% stable disease [SD]). Among MBCts (8/12 had prior EB+CDK4/6i), DCR ≥12 wks was 91.7%; 1 pt had sustained PR for 48 wks and 1 ongoing PR at 40 wks. 9/16 pts had RET+ tumors on immunohistochemistry at baseline, and 66.7% showed down-regulation with Tx (RECIST: 4 PR, 2 SD). Conclusions: Len+Let showed significant anti-tumor activity, even in pts who failed prior CT or EB+CDK4/6i. RP2D of 14mg Len and 2.5mg Let is tolerated with efficacy; dose expansion is currently underway. Clinical trial information: NCT02562118. [Table: see text]

Tumor pathological and immunological changes in HER2+ metastatic breast cancer (MBC) following trastuzumab combined with expanded and activated autologous natural killer (NK) cell infusion

e12511

Background: A central mechanism for the anti-tumor activity of Trastuzumab, a HER2 monoclonal antibody, against HER2+ tumors is induction of antibody dependent cell cytotoxicity (ADCC) mediated by NK cells. We are conducting a first-in-human trial of Trastuzumab followed by infusion of expanded, activated autologous NK cells in refractory HER2+ MBC (ClinicalTrials.gov: NCT02030561) to test the hypothesis that NK cell infusions will augment Trastuzumab-mediated ADCC and increase immune cell infiltration in tumor. Pre- and post-infusion tumor biopsies were obtained in a subset of patients to determine degree of NK cell infiltration in tumor and histopathological and immunological effects after infusion. Methods: HER2+ MBC patients underwent apheresis to harvest NK cells for ex vivo expansion and activation. NK cells (107/kg), expressing high levels of the antibody receptor CD16, were infused 24 hours post-Trastuzumab. Histology analysis and immunohistochemistry with CD56, CD3, CD20 and cleaved caspase-3 to identify NK, T, B, and apoptotic cells respectively, was performed in pre- and post-infusion biopsies. Studies of CD4 and CD8 to further classify T cell infiltrates, and CD16 to assess NK cell functionality are underway. Results: Analysis of 7 paired tumor biopsies collected before and 7-14 days after NK cell infusion showed absolute increase in lymphocyte infiltration (mean cell count/5 HPF: 204 vs 265 in pre- vs post- biopsy, p = 0.109). Most infiltrating lymphocytes were CD3+ T cells (74.28±12.72% vs 80 ±10% in pre vs post) and CD56+ NK cell number in the immune infiltrate were increased post infusion (mean cell count/5 HPF: 4.57±3.46 vs 20.57±13.83 in pre vs post; p = 0.009). Increased tumor apoptosis was observed post NK cell infusion (mean apoptotic cell count/5 HPF: 3.14±2.48 vs 5.86±6.72 in pre vs post, p = 0.27). Conclusions: Histopathology analysis of tumors from HER2+ MBC patients demonstrated significant increase in NK and T cells in tumor following Trastuzumab and NK cell infusion, suggesting that this combination might also augment recruitment of T lymphocytes into tumor, further enhancing anti-tumor activity. Clinical trial information: NCT02030561.

Discoveries beyond BRCA1/2: Multigene testing in an Asian multi-ethnic cohort suspected of hereditary breast cancer syndrome in the real world

BACKGROUND

Due to historically low uptake of genetic testing, the mutational spectrum of Asians with Hereditary Breast Cancer (HBC) is not well understood. This study sought to understand the incidence and spectrum of germline mutations in Asian patients with suspected HBC in a clinic setting.

METHODS

1056 patients with suspected HBC were seen in our Cancer (CA) Genetics Clinic from 2000-2017, of which 460 underwent genetic testing.

RESULTS

Of 460 probands tested, 93% were female, 61% Chinese, 90% had prior CA, with 19% (77/414) having ≥2 primary CA. Median age at CA-diagnosis was 43y (17-83); 70% had Breast CA (BC) and 25% Ovarian CA (OC). 34% had young-onset BC, 8% bilateral BC, and 4% BC/OC. Majority had family history of BC (53%) or OC (20%). 57% underwent multigene testing (14-49 genes), 34% targeted testing, and 8% predictive testing. 30% were found to have a pathogenic mutation: 80% in BRCA1/2 (8 novel mutations noted). Of 33 non-BRCA1/2 pathogenic mutations detected, 61% were in 11 BC genes while 39% were in non-BC genes suggestive of alternative CA syndromes. Testing beyond BRCA1/2 impacted management for 15.9% (22/138) of carriers, but extensive testing identified variants of uncertain significance (VUS) in up to 44.5% of probands. Restricting multigene panel testing to a guideline-based 20-gene panel including Lynch Syndrome genes was found to be most optimal, detecting 94.6% of mutation carriers while reducing VUS rate to 21.5%.

CONCLUSIONS

Evolution of CA Genetics testing strategy to a multigene approach facilitated detection of pathogenic mutations in non-BRCA1/2 genes and aided management. Guideline-based panel testing is feasible and can be offered in Asians with suspected HBC.

Multi-gene panel testing of patients with multiple primary malignancies suspected with hereditary cancer syndrome

1512

Background: Developing multiple primary cancers is an indicator of underlying hereditary cancer predisposition, but there is a paucity of data regarding the characteristics and clinical genetic testing outcome of these patients. Methods: We compared cancer index patients with 1 vs > 1 primary malignancy who underwent evaluation and clinical testing with multi-gene panels comprising up to 49 genes in a cancer genetics clinic in a tertiary cancer centre in Asia from 1998-2016. Results: Among 1191 cancer index patients, 960 (80.6%), 205 (17.2%), and 26 (2.2%) respectively had 1, 2, and ≥3 primary malignancies. Among patients with > 1 primary cancers (n = 231), the most common cancer pairs were breast-breast (35.4%), breast-ovary (12.1%), endometrium-ovary (8.2%), colon-colon (2.4%) and, colon-endometrium (2.4%). The mean age at diagnosis of the first, second and third cancers were 46.0 (21 to 87), 52.1 (21 to 89) and 57.7 (41 to 83) respectively. The mean duration between first and second cancers is 6.0 years (0 to 32). The most commonly suspected syndromes in patients with 1 vs > 1 primary cancer were hereditary breast and ovarian cancer 63.8% vs 53.6%, Lynch 24.8% vs 31.1%, Li-Fraumeni syndromes 1.8% vs 1.7%, and others 9.3% vs 13.4% (p = 0.03). Patients with > 1 primary cancer were more likely to have > 20% a priori risk of suspected hereditary cancer syndrome (42.8% vs. 26.5%; p < 0.001). 504/1191 (42.3%) patients underwent gene testing, including 394/960 (41.0%) and 110/231 (47.6%) patients with 1 vs > 1 cancer. Deleterious mutations were more likely to be identified in patients with > 1 vs 1 cancer (34.5% vs. 25.8%; p = 0.073), with causative genes being BRCA1 38.5%, BRCA2 17.9%, MLH1/MSH2/MSH6 20.5%, TP53 7.7%, and others (ATM [n = 2], MUTYH, APC, PALB2, RAD51 [n = 1 each]) for patients with > 1 cancer. VUS rates were 31.7% vs.31.8% in patients with 1 vs > 1 cancer, and were identified in genes including BRIP1, CHEK2, PALLD, POLE, PTEN, STK11, SMARCA4, and VHL. Conclusions: Patients with > 1 primary cancer comprised one-fifth of cancer index patients evaluated at a cancer genetics clinic, and were more likely to be found with deleterious mutations than patients with only 1 cancer on multi-gene panel testing.

Whole exome sequencing (WES) of multiple spatially distinct biopsies from single metastatic lesions to evaluate tumour heterogeneity and identify actionable truncal mutations (ATMs) in patients (pts) with advanced solid malignancies using a radiologically-guided single-pass percutaneous technique

2550

Background: Genomic profiling of single core biopsies (bx) are confounded intratumoral heterogeneity, resulting in sampling bias. We explored the use of a novel technique to obtain multiple bx from single metastatic lesion in pts to evaluate heterogeneity and identify therapeutic ATM. Methods: 15 pts (5 NSCLC; 3 ovarian; 2 colon, 2 uterine and 1 breast, cervix and HCC) with biopsiable lesions were identified. Using a single pass radiologically guided percutaneous bx technique, we obtained multiple spatially distinct core bx samples from a single metastatic lesion. Each bx underwent DNA extraction and WES using the NextSeq500. Results: Median of 4 core bx were obtained from each lesion. Complication rate utilizing this technique was 0%. 2 pts were omitted from analysis due to poor quality DNA with 13 pts successfully sequenced. In 1 pt, only 2 of 4 cores were successfully sequenced. The median amounts of total and non-synonymous variants were 137 (27-1286) and 66 (10-649) respectively. The median (range) filtered variants detected in 1/4, 2/4, 3/4, and 4/4 bx cores was 63(16-91)%, 5(1-65)%, 4(0-30)% and 26(0-63)% respectively, suggesting significant subclonal diversity within a single lesion. ATMs were identitified in 8/13 pts. 4/13 pts (31%) had no ATM across all 4 cores. 3 pts received therapy with inhibitors targeting ATMs. A pt with AKT1_E17K ATM received an AKT inhibitor with 21% tumour shrinkage and PFS 6.1 mths. 2 NSCLC pts harbouring an EGFR_T790M ATM were treated with an EGFRT790M specific TKI. 1 withdrew due to toxicity after 2mths and another had PFS > 16.5 mths. Tumour mutational burden (TMB) was consistent across multiple bx from each lesion. A NSCLC pt with the highest TMB received a checkpoint inhibitor with ongoing > 4 mths stable disease. Conclusions: Utilizing a single pass radiologically guided techniqueto obtainmultiple bx is feasible, safe and informative. This allows reconstruction of a tumour’s subclonal genomic architecture, providing insights into mutational heterogeneity and help guide therapy.

Prospective study of UDP-glucuronosyltransferase (UGT) 2B17 genotype and exemestane (Exe) pharmacokinetics (PK) and pharmacodynamics (PD) in Asian, hormone receptor (HR) positive, metastatic breast cancer (MBC) patients

1056

Background: The active metabolite of Exe, 17-dihydroexemestane (17DhExe), is glucuronidated by UGT2B17 to inactive exemestane-17-O-glucuronide (Exe17- O-glu). UGT2B17*2/*2null genotype is 7 times more common in Asians than Caucasians and leads to reduced Exe glucuronidation in vitro. We studied Exe PK and PD in MBC patients genotyped for UGT2B17. Methods: Eligible patients (HR+ MBC; ≥1 line of endocrine therapy) received Exe 25mg OD till progression. UGBT2B17 genotype was correlated with day 29 (D29) steady-state PK (Exe and metabolites), change in PD biomarkers (estrone and androstenedione) at D29 vs baseline (BL), objective response rate (ORR) [sum of complete and partial responses], and clinical benefit rate (CBR) [response or stable disease ≥ 24 weeks]. Results: In 64 patients enrolled, CBR was 25%; ORR was 3%. Frequencies of UGT2B17*2/*2, UGT2B17*1/*2 and UGT2B17*1/*1 were 72%, 26% and 2%, respectively. PD and PK data were available for 54 and 53 patients respectively. Mean Exe17- O-glu AUC and Cmax were significantly lower, and mean 17DhExe Cmax numerically higher in patients with UGT2B17*2/*2 vs other genotypes (Table 1). 17DhExe Cmax was higher in patients with clinical benefit vs none (5.6 vs 3.8 ng/ml, p=0.02). Frequency of desired PD effect (rise in androstenedione and fall in estrone at D29 vs BL) was 22%. Exe plasma active index (PAI) [Table 1] was higher in patients with a fall in D29 estrone vs those without (14.7 vs 9.5, p=0.05). Conclusions: UGT2B17 genotype affects Exe PK and may have significant PD correlates. Larger studies to examine effects on clinical treatment efficacy are needed. Clinical trial information: NCT01655004. [Table: see text]

Limb Hypothermia for Preventing Paclitaxel-Induced Peripheral Neuropathy in Breast Cancer Patients: A Pilot Study

BACKGROUND

Peripheral neuropathy (PN) due to paclitaxel is a common dose-limiting toxicity with no effective prevention or treatment. We hypothesize that continuous-flow limb hypothermia can reduce paclitaxel-induced PN.

PATIENTS AND METHODS

An internally controlled pilot trial was conducted to investigate the neuroprotective effect of continuous-flow limb hypothermia in breast cancer patients receiving weekly paclitaxel. Patients underwent limb hypothermia of one limb for a duration of 3 h with every paclitaxel infusion, with the contralateral limb used as control. PN was primarily assessed using nerve conduction studies (NCSs) before the start of chemotherapy, and after 1, 3, and 6 months. Skin temperature and tolerability to hypothermia were monitored using validated scores.

RESULTS

Twenty patients underwent a total of 218 cycles of continuous-flow limb hypothermia at a coolant temperature of 22°C. Continuous-flow limb hypothermia achieved mean skin temperature reduction of 1.5 ± 0.7°C and was well tolerated, with no premature termination of cooling due to intolerance. Grade 3 PN occurred in 2 patients (10%), grade 2 in 2 (10%), and grade 1 in 12 (60%). Significant correlation was observed between amount of skin cooling and motor nerve amplitude preservation at 6 months (p < 0.0005). Sensory velocity and amplitude in the cooled limbs were less preserved than in the control limbs, but the difference did not attain statistical significance. One patient with a history of diabetes mellitus had significant preservation of compound muscle action potential in the cooled limb on NCS analysis.

CONCLUSION

This study suggests that continuous limb hypothermia accompanying paclitaxel infusion may reduce paclitaxel-induced PN and have therapeutic potential in select patients and warrants further investigation. The method is safe and well tolerated.

Low Levels of NDRG1 in Nerve Tissue Are Predictive of Severe Paclitaxel-Induced Neuropathy

Introduction

Sensory peripheral neuropathy caused by paclitaxel is a common and dose limiting toxicity, for which there are currently no validated predictive biomarkers. We investigated the relationship between the Charcot-Marie-Tooth protein NDRG1 and paclitaxel-induced neuropathy.

Methods/Materials

Archived mammary tissue specimen blocks of breast cancer patients who received weekly paclitaxel in a single centre were retrieved and NDRG1 immunohistochemistry was performed on normal nerve tissue found within the sample. The mean nerve NDRG1 score was defined by an algorithm based on intensity of staining and percentage of stained nerve bundles. NDRG1 scores were correlated with paclitaxel induced neuropathy

Results

111 patients were studied. 17 of 111 (15%) developed severe paclitaxel-induced neuropathy. The mean nerve NDRG1 expression score was 5.4 in patients with severe neuropathy versus 7.7 in those without severe neuropathy (p = 0.0019). A Receiver operating characteristic (ROC) curve analysis of the mean nerve NDRG1 score revealed an area under the curve of 0.74 (p = 0.0013) for the identification of severe neuropathy, with a score of 7 being most discriminative. 13/54 (24%) subjects with an NDRG1 score < = 7 developed severe neuropathy, compared to only 4/57 (7%) in those with a score >7 (p = 0.017).

Conclusion

Low NDRG1 expression in nerve tissue present within samples of surgical resection may identify subjects at risk for severe paclitaxel-induced neuropathy. Since nerve biopsies are not routinely feasible for patients undergoing chemotherapy for early breast cancer, this promising biomarker strategy is compatible with current clinical workflow.

The optimization of 5-fluorouracil (5FU) dose by pharmacokinetic (PK) monitoring in Asian patients with advanced-stage gastrointestinal (GI) cancer

770

Background: PK guided dose management and systemic plasma levels of 5FU have shown correlation with both reduced toxicity and improved efficacy. However, data for Asian patients are lacking. Levels are highly variable with doses based on body surface area. Methods: Area under the curve (AUC) was estimated using a nanoparticle immunoassay from Saladax Biomedical (My5-FU). Patients with GI cancers receiving de Gramont, FOLFIRI or mFOLFOX6 regimens had 5 PK sampling time points obtained (reduced to 2 samplings after first 15 patients). If target AUC (18-28 mg.h/L) was reached for 2 consecutive cycles, monitoring is performed for alternate cycles. With dose adjustments, PK sampling will be done in the next cycle. Results: 50 patients (33 males, 17 females) enrolled, with 349 PK samplings done, and 291 analyzable. 31 (62%) had mFOLFOX6, 18 (36%) FOLIRI and 1 (2%) de Gramont. Colorectal cancer (76%) and gastric cancer (12%) were the most common cancer types. Median AUC (35 evaluable) was 24.2 in C1, 23.65 in C2 (n=38), 20.6 in C3 (n=38) and 22 mg.hr/L in C4 (n=35). Proportion of patients achieving target AUC were 54.3%, 32%, 39.5% and 51% respectively and did not change significantly despite PK guided doses adjustments (C1 vs. C4 p=0.81, C2 vs. C3 p= 0.63, C2 vs. C4 p=0.085, C3 vs. C4 p=0.31). Higher than expected rate of G3/4 neutropenia (52%) and fewer mucositis (0%) and diarrhea (8%) were observed. Other toxicities (all grades) were fairly consistent with historical data. There were no inter-cycle differences in rates of toxicity, and no relationship with G3/4 toxicities and high AUC levels were observed. Correlation of response rates, efficacy with AUC were omitted due to heterogeneous tumor types. Conclusions: Contrary to past studies, PK guided 5FU did not result in a greater number of patients achieving target AUC in Asian patients. Furthermore, AUC levels of 5FU did not correlate with toxicity. Larger numbers are needed to confirm the clinical utility and benefit of PK guided 5FU in Asian patients. Clinical trial information: NCT00943137.

Inadequate family history assessment by oncologists as a physician barrier to referral for cancer genetics evaluation

1535

Background: Cancer genetics programs have been established in tertiary cancer centers in Asia for more than a decade. However, the proportion of high-risk patients who are referred for genetic evaluation remains low, and may be attributed to physician and patient barriers. Methods: We reviewed 3-generation genograms of 6301 cancer (CA) patients constructed by a trained cancer genetics counselor at our centre between 2001 and 2012, and identified 1092 (17.3%) patients with suspected hereditary cancer syndromes. 618 patients were estimated to have ≥10% chance of carrying a BRCA1/2 mutation. Their case records were reviewed to determine the referral pattern to the cancer genetics clinic. Results: Of the 618 high risk patients, 420 (68%) had young onset CA (age <40), 112 (18.1%) were breast CA families, and 58 (9.4%) were breast and ovarian CA families; only 164 (26.5%) were seen in the cancer genetics clinic. Of the 391 records reviewed so far, 132 cases (33.8%) were referred for genetic evaluation. A good family history (FH), defined by obtaining CA history in 3 consecutive generations, was obtained by the primary oncologist in 52.2%, compared to adequate smoking and drinking history in 64.7% of cases (p<0.001). Taking a good FH increased the likelihood of oncologists suspecting hereditary breast and ovarian CA syndrome (50% vs 32.1%; p<0.001), with 79% (128/162) of physician-suspected cases referred for genetic counseling. Young onset CA was more likely to arouse physician suspicion (46.9%) compared to other indications (30.5%, p=0.002). Of the 259 high-risk cases that were not referred, lack of FH evaluation by the oncologist was the most common reason (41.3 %), followed by lack of suspicion despite taking a FH (34.7 %), patient refusal (8.6%), and planned but no formal action (1.6%). Conclusions: Failure to take a good FH and failure to recognize high-risk CA patients despite taking a FH are important physician barriers that resulted in only a third of high-risk breast or ovarian CA patients being referred for cancer genetics evaluation at a tertiary cancer center in Asia. Systematic FH screening by genetic counselors, clinic-based protocols, and continued physician education may rectify this barrier.