Clinical management of TP53 mosaic variants found on germline genetic testing

BACKGROUND

Germline heterozygous TP53 pathogenic variants (PVs) cause Li Fraumeni Syndrome (LFS, OMIM#151623). TP53 PVs at lower-than-expected variant allele frequencies (VAF) may reflect postzygotic mosaicism (PZM) or clonal hematopoiesis (CH); however, no guidelines exist for workup and clinical management.

PATIENTS AND METHODS

Retrospective analysis of probands who presented to an academic cancer genetics program with a TP53 PV result on germline genetic testing.

RESULTS

Twenty-one of 125 unrelated probands (17 %) were found to harbor a TP53 PV with VAF<30 % or a designation of "mosaic". A diagnosis of PZM was made in nine (43 %) due to a clinical phenotype consistent with LFS with (n = 8) or without (n = 1) positive ancillary tissue testing. Twelve patients (57 %) were diagnosed with presumed CH (pCH) due to a diagnosis of a myeloproliferative neoplasm, negative ancillary tissue testing, clinical phenotype not meeting LFS criteria, no cancer, and/or no first cancer age<50. Of the 19 patients with biological offspring, nine had either partial or complete offspring testing, all negative.

CONCLUSIONS

Determining the etiology of low VAF TP53 PVs requires ancillary tissue testing and incorporation of clinical phenotype. Discerning PZM versus CH is important to provide optimal care and follow-up.

Prevalence of H. pylori and gastric intestinal metaplasia in BRCA1 and BRCA2 carriers

BRCA1 and BRCA2 carriers may be at increased risk for gastric cancer (GC), however the mechanisms of gastric carcinogenesis remain poorly understood. We sought to determine the prevalence of GC risk factors Helicobacter pylori (H. pylori) infection and gastric intestinal metaplasia (GIM) among BRCA1/2 carriers to gain insight into the pathogenesis of GC in this population. 100 unselected BRCA1/2 carriers undergoing endoscopic ultrasound from 3/2022-3/2023 underwent concomitant upper endoscopy with non-targeted gastric antrum and body biopsies. The study population (70% women; mean age: 60.1) included 66% BRCA2 carriers. H. pylori was detected in one (1%) individual, 7 (7%) had GIM, 2 (2%) had autoimmune atrophic gastritis, and no GCs were diagnosed. Among BRCA1/2 carriers, H. pylori prevalence was low and GIM prevalence was similar to the general population, however identification of H. pylori or GIM may help inform future GC risk management strategies in BRCA1/2 carriers.

Patient-Reported Outcomes in OlympiA: A Phase III, Randomized, Placebo-Controlled Trial of Adjuvant Olaparib in gBRCA1/2 Mutations and High-Risk Human Epidermal Growth Factor Receptor 2-Negative Early Breast Cancer

PURPOSE

The OlympiA randomized phase III trial compared 1 year of olaparib (OL) or placebo (PL) as adjuvant therapy in patients with germline BRCA1/2, high-risk human epidermal growth factor receptor 2-negative early breast cancer after completing (neo)adjuvant chemotherapy ([N]ACT), surgery, and radiotherapy. The patient-reported outcome primary hypothesis was that OL-treated patients may experience greater fatigue during treatment.

METHODS

Data were collected before random assignment, and at 6, 12, 18, and 24 months. The primary end point was fatigue, measured with the Functional Assessment of Chronic Illness Therapy-Fatigue scale. Secondary end points, assessed with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire, Core 30 item, included nausea and vomiting (NV), diarrhea, and multiple functional domains. Scores were compared between treatment groups using mixed model for repeated measures. Two-sided P values <.05 were statistically significant for the primary end point. All secondary end points were descriptive.

RESULTS

One thousand five hundred and thirty-eight patients (NACT: 746, ACT: 792) contributed to the analysis. Fatigue severity was statistically significantly greater for OL versus PL, but not clinically meaningfully different by prespecified criteria (≥3 points) at 6 months (diff OL v PL: NACT: -1.3 [95% CI, -2.4 to -0.2]; P = .022; ACT: -1.3 [95% CI, -2.3 to -0.2]; P = .017) and 12 months (NACT: -1.6 [95% CI, -2.8 to -0.3]; P = .017; ACT: -1.3 [95% CI, -2.4 to -0.2]; P = .025). There were no significant differences in fatigue severity between treatment groups at 18 and 24 months. NV severity was worse in patients treated with OL compared with PL at 6 months (NACT: 6.0 [95% CI, 4.1 to 8.0]; ACT: 5.3 [95% CI, 3.4 to 7.2]) and 12 months (NACT: 6.4 [95% CI, 4.4 to 8.3]; ACT: 4.5 [95% CI, 2.8 to 6.1]). During treatment, there were some clinically meaningful differences between groups for other symptoms but not for function subscales or global health status.

CONCLUSION

Treatment-emergent symptoms from OL were limited, generally resolving after treatment ended. OL- and PL-treated patients had similar functional scores, slowly improving during the 24 months after (N)ACT and there was no clinically meaningful persistence of fatigue severity in OL-treated patients.

Advancing Cancer Interception

Rapid advances in technology and therapeutics, along with better methods to discern who is at risk for cancer by genetic testing and other means, has enabled the development of cancer interception. Targeted therapies and "immuno-interception" may eliminate premalignant lesions and require clinical trial and treatment paradigms altogether distinct from current approaches.

Functional analysis and clinical classification of 462 germline BRCA2 missense variants affecting the DNA binding domain

Variants of uncertain significance (VUSs) in BRCA2 are a common result of hereditary cancer genetic testing. While more than 4,000 unique VUSs, comprised of missense or intronic variants, have been identified in BRCA2, the few missense variants now classified clinically as pathogenic or likely pathogenic are predominantly located in the region encoding the C-terminal DNA binding domain (DBD). We report on functional evaluation of the influence of 462 BRCA2 missense variants affecting the DBD on DNA repair activity of BRCA2 using a homology-directed DNA double-strand break repair assay. Of these, 137 were functionally abnormal, 313 were functionally normal, and 12 demonstrated intermediate function. Comparisons with other functional studies of BRCA2 missense variants yielded strong correlations. Sequence-based in silico prediction models had high sensitivity, but limited specificity, relative to the homology-directed repair assay. Combining the functional results with clinical and genetic data in an American College of Medical Genetics (ACMG)/Association for Molecular Pathology (AMP)-like variant classification framework from a clinical testing laboratory, after excluding known splicing variants and functionally intermediate variants, classified 431 of 442 (97.5%) missense variants (129 as pathogenic/likely pathogenic and 302 as benign/likely benign). Functionally abnormal variants classified as pathogenic by ACMG/AMP rules were associated with a slightly lower risk of breast cancer (odds ratio [OR] 5.15, 95% confidence interval [CI] 3.43-7.83) than BRCA2 DBD protein truncating variants (OR 8.56, 95% CI 6.03-12.36). Overall, functional studies of BRCA2 variants using validated assays substantially improved the variant classification yield from ACMG/AMP models and are expected to improve clinical management of many individuals found to harbor germline BRCA2 missense VUS.

Large-scale genome-wide association study of 398,238 women unveils seven novel loci associated with high-grade serous epithelial ovarian cancer risk

Background

Nineteen genomic regions have been associated with high-grade serous ovarian cancer (HGSOC). We used data from the Ovarian Cancer Association Consortium (OCAC), Consortium of Investigators of Modifiers of BRCA1/BRCA2 (CIMBA), UK Biobank (UKBB), and FinnGen to identify novel HGSOC susceptibility loci and develop polygenic scores (PGS).

Methods

We analyzed >22 million variants for 398,238 women. Associations were assessed separately by consortium and meta-analysed. OCAC and CIMBA data were used to develop PGS which were trained on FinnGen data and validated in UKBB and BioBank Japan.

Results

Eight novel variants were associated with HGSOC risk. An interesting discovery biologically was finding that TP53 3'-UTR SNP rs78378222 was associated with HGSOC (per T allele relative risk (RR)=1.44, 95%CI:1.28-1.62, P=1.76×10-9). The optimal PGS included 64,518 variants and was associated with an odds ratio of 1.46 (95%CI:1.37-1.54) per standard deviation in the UKBB validation (AUROC curve=0.61, 95%CI:0.59-0.62).

Conclusions

This study represents the largest GWAS for HGSOC to date. The results highlight that improvements in imputation reference panels and increased sample sizes can identify HGSOC associated variants that previously went undetected, resulting in improved PGS. The use of updated PGS in cancer risk prediction algorithms will then improve personalized risk prediction for HGSOC.

Olaparib plus Durvalumab, with or without Bevacizumab, as Treatment in PARP Inhibitor-Naïve Platinum-Sensitive Relapsed Ovarian Cancer: A Phase II Multi-Cohort Study

PURPOSE

Early results from the phase II MEDIOLA study (NCT02734004) in germline BRCA1- and/or BRCA2-mutated (gBRCAm) platinum-sensitive relapsed ovarian cancer (PSROC) showed promising efficacy and safety with olaparib plus durvalumab. We report efficacy and safety of olaparib plus durvalumab in an expansion cohort of women with gBRCAm PSROC (gBRCAm expansion doublet cohort) and two cohorts with non-gBRCAm PSROC, one of which also received bevacizumab (non-gBRCAm doublet and triplet cohorts).

PATIENTS AND METHODS

In this open-label, multicenter study, PARP inhibitor-naïve patients received olaparib plus durvalumab treatment until disease progression; the non-gBRCAm triplet cohort also received bevacizumab. Primary endpoints were objective response rate (ORR; gBRCAm expansion doublet cohort), disease control rate (DCR) at 24 weeks (non-gBRCAm cohorts), and safety (all cohorts).

RESULTS

The full analysis and safety analysis sets comprised 51, 32, and 31 patients in the gBRCAm expansion doublet, non-gBRCAm doublet, and non-gBRCAm triplet cohorts, respectively. ORR was 92.2% [95% confidence interval (CI), 81.1-97.8] in the gBRCAm expansion doublet cohort (primary endpoint); DCR at 24 weeks was 28.1% (90% CI, 15.5-43.9) in the non-gBRCAm doublet cohort (primary endpoint) and 74.2% (90% CI, 58.2-86.5) in the non-gBRCAm triplet cohort (primary endpoint). Grade ≥ 3 adverse events were reported in 47.1%, 65.6%, and 61.3% of patients in the gBRCAm expansion doublet, non-gBRCAm doublet, and non-gBRCAm triplet cohorts, respectively, most commonly anemia.

CONCLUSIONS

Olaparib plus durvalumab continued to show notable clinical activity in women with gBRCAm PSROC. Olaparib plus durvalumab with bevacizumab demonstrated encouraging clinical activity in women with non-gBRCAm PSROC. No new safety signals were identified.

Germline Genetic Testing for Hereditary Breast and Ovarian Cancer: Current Concepts in Risk Evaluation

Our understanding of hereditary breast and ovarian cancer has significantly improved over the past two decades. In addition to BRCA1/2, pathogenic variants in several other DNA-repair genes have been shown to increase the risks of breast and ovarian cancer. The magnitude of cancer risk is impacted not only by the gene involved, but also by family history of cancer, polygenic risk scores, and, in certain genes, pathogenic variant type or location. While estimates of breast and ovarian cancer risk associated with pathogenic variants are available, these are predominantly based on studies of high-risk populations with young age at diagnosis of cancer, multiple primary cancers, or family history of cancer. More recently, breast cancer risk for germline pathogenic variant carriers has been estimated from population-based studies. Here, we provide a review of the field of germline genetic testing and risk evaluation for hereditary breast and ovarian cancers in high-risk and population-based settings.

The Clinical Implications of Reversions in Patients with Advanced Pancreatic Cancer and Pathogenic Variants in BRCA1, BRCA2, or PALB2 after Progression on Rucaparib

PURPOSE

PARP inhibitors (PARPi) provide an effective maintenance option for patients with BRCA- or PALB2-mutated pancreatic cancer. However, mechanisms of PARPi resistance and optimal post-PARPi therapeutic strategies are poorly characterized.

EXPERIMENTAL DESIGN

We collected paired cell-free DNA samples and post-PARPi clinical data on 42 patients with advanced, platinum-sensitive pancreatic cancer who were treated with maintenance rucaparib on NCT03140670, of whom 32 developed progressive disease.

RESULTS

Peripherally detected, acquired BRCA or PALB2 reversion variants were uncommon (5/30; 16.6%) in patients who progressed on rucaparib. Reversions were significantly associated with rapid resistance to PARPi treatment (median PFS, 3.7 vs. 12.5 months; P = 0.001) and poor overall survival (median OS, 6.2 vs. 23.0 months; P < 0.0001). All patients with reversions received rechallenge with platinum-based chemotherapy following PARPi progression and experienced faster progression on this therapy than those without reversion variants (real-world time-to-treatment discontinuation, 2.4 vs. 5.8 months; P = 0.004). Of the patients who progressed on PARPi and received further chemotherapy, the OS from initiation of second-line therapy was significantly lower in those with reversion variants than in those without (5.5 vs. 12.0 months, P = 0.002). Finally, high levels of tumor shedding were independently associated with poor outcomes in patients who received rucaparib.

CONCLUSIONS

Acquired reversion variants were uncommon but detrimental in a population of patients with advanced BRCA- or PALB2-related pancreatic ductal adenocarcinoma who received maintenance rucaparib. Reversion variants led to rapid progression on PARPi, rapid failure of subsequent platinum-based treatment, and poor OS of patients. The identification of such variants in the blood may have both predictive and prognostic value. See related commentary by Tsang and Gallinger, p. 5005.

Saturation genome editing-based functional evaluation and clinical classification of BRCA2 single nucleotide variants

Germline BRCA2 loss-of function (LOF) variants identified by clinical genetic testing predispose to breast, ovarian, prostate and pancreatic cancer. However, variants of uncertain significance (VUS) (n>4000) limit the clinical use of testing results. Thus, there is an urgent need for functional characterization and clinical classification of all BRCA2 variants. Here we report on comprehensive saturation genome editing-based functional characterization of 97% of all possible single nucleotide variants (SNVs) in the BRCA2 DNA Binding Domain hotspot for pathogenic missense variants that is encoded by exons 15 to 26. The assay was based on deep sequence analysis of surviving endogenously targeted haploid cells. A total of 7013 SNVs were characterized as functionally abnormal (n=955), intermediate/uncertain, or functionally normal (n=5224) based on 95% agreement with ClinVar known pathogenic and benign standards. Results were validated relative to batches of nonsense and synonymous variants and variants evaluated using a homology directed repair (HDR) functional assay. Breast cancer case-control association studies showed that pooled SNVs encoding functionally abnormal missense variants were associated with increased risk of breast cancer (odds ratio (OR) 3.89, 95%CI: 2.77-5.51). In addition, 86% of tumors associated with abnormal missense SNVs displayed loss of heterozygosity (LOH), whereas 26% of tumors with normal variants had LOH. The functional data were added to other sources of information in a ClinGen/ACMG/AMP-like model and 700 functionally abnormal SNVs, including 220 missense SNVs, were classified as pathogenic or likely pathogenic, while 4862 functionally normal SNVs, including 3084 missense SNVs, were classified as benign or likely benign. These classified variants can now be used for risk assessment and clinical care of variant carriers and the remaining functional scores can be used directly for clinical classification and interpretation of many additional variants.

Summary

Germline BRCA2 loss-of function (LOF) variants identified by clinical genetic testing predispose to several types of cancer. However, variants of uncertain significance (VUS) limit the clinical use of testing results. Thus, there is an urgent need for functional characterization and clinical classification of all BRCA2 variants to facilitate current and future clinical management of individuals with these variants. Here we show the results from a saturation genome editing (SGE) and functional analysis of all possible single nucleotide variants (SNVs) from exons 15 to 26 that encode the BRCA2 DNA Binding Domain hotspot for pathogenic missense variants. The assay was based on deep sequence analysis of surviving endogenously targeted human haploid HAP1 cells. The assay was calibrated relative to ClinVar known pathogenic and benign missense standards and 95% prevalence thresholds for functionally abnormal and normal variants were identified. Thresholds were validated based on nonsense and synonymous variants. SNVs encoding functionally abnormal missense variants were associated with increased risks of breast and ovarian cancer. The functional assay results were integrated into a ClinGen/ACMG/AMP-like model for clinical classification of the majority of BRCA2 SNVs as pathogenic/likely pathogenic or benign/likely benign. The classified variants can be used for improved clinical management of variant carriers.

Protocol to evaluate sequential electronic health record-based strategies to increase genetic testing for breast and ovarian cancer risk across diverse patient populations in gynecology practices

BACKGROUND

Germline genetic testing is recommended by the National Comprehensive Cancer Network (NCCN) for individuals including, but not limited to, those with a personal history of ovarian cancer, young-onset (< 50 years) breast cancer, and a family history of ovarian cancer or male breast cancer. Genetic testing is underused overall, and rates are consistently lower among Black and Hispanic populations. Behavioral economics-informed implementation strategies, or nudges, directed towards patients and clinicians may increase the use of this evidence-based clinical practice.

METHODS

Patients meeting eligibility for germline genetic testing for breast and ovarian cancer will be identified using electronic phenotyping algorithms. A pragmatic cohort study will test three sequential strategies to promote genetic testing, two directed at patients and one directed at clinicians, deployed in the electronic health record (EHR) for patients in OB-GYN clinics across a diverse academic medical center. We will use rapid cycle approaches informed by relevant clinician and patient experiences, health equity, and behavioral economics to optimize and de-risk our strategies and methods before trial initiation. Step 1 will send patients messages through the health system patient portal. For non-responders, step 2 will reach out to patients via text message. For non-responders, Step 3 will contact patients' clinicians using a novel "pend and send" tool in the EHR. The primary implementation outcome is engagement with germline genetic testing for breast and ovarian cancer predisposition, defined as a scheduled genetic counseling appointment. Patient data collected through the EHR (e.g., race/ethnicity, geocoded address) will be examined as moderators of the impact of the strategies.

DISCUSSION

This study will be one of the first to sequentially examine the effects of patient- and clinician-directed strategies informed by behavioral economics on engagement with breast and ovarian cancer genetic testing. The pragmatic and sequential design will facilitate a large and diverse patient sample, allow for the assessment of incremental gains from different implementation strategies, and permit the assessment of moderators of strategy effectiveness. The findings may help determine the impact of low-cost, highly transportable implementation strategies that can be integrated into healthcare systems to improve the use of genomic medicine.

TRIAL REGISTRATION

ClinicalTrials.gov. NCT05721326. Registered February 10, 2023. https://www.

CLINICALTRIALS

gov/study/NCT05721326.

Analysis of BRCA1- and BRCA2-Related Pancreatic Cancer and Survival

This cohort study compares the outcomes of patients with BRCA1 and BRCA-related pancreatic cancers using 2 large data sets.

Care after premenopausal risk-reducing salpingo-oophorectomy in high-risk women: Scoping review and international consensus recommendations

Women at high inherited risk of ovarian cancer are offered risk-reducing salpingo-oophorectomy (RRSO) from age 35 to 45 years. Although potentially life-saving, RRSO may induce symptoms that negatively affect quality of life and impair long-term health. Clinical care following RRSO is often suboptimal. This scoping review describes how RRSO affects short- and long-term health and provides evidence-based international consensus recommendations for care from preoperative counselling to long-term disease prevention. This includes the efficacy and safety of hormonal and non-hormonal treatments for vasomotor symptoms, sleep disturbance and sexual dysfunction and effective approaches to prevent bone and cardiovascular disease.

Uptake of Genetic Research Results and Patient-Reported Outcomes With Return of Results Incorporating Web-Based Predisclosure Education

PURPOSE

We developed a web-based education intervention as an alternative to predisclosure education with a genetic counselor (GC) to reduce participant burden and provider costs with return of genetic research results.

METHODS

Women at three sites who participated in 11 gene discovery research studies were contacted to consider receiving cancer genetic research results. Participants could complete predisclosure education through web education or with a GC. Outcomes included uptake of research results, factors associated with uptake, and patient-reported outcomes.

RESULTS

Of 819 participants, 178 actively (21.7%) and 167 passively (20.4%) declined return of results; 474 (57.9%) were enrolled. Most (60.3%) received results although this was lower than the 70% uptake we hypothesized. Passive and active decliners were more likely to be Black, to have less education, and to have not received phone follow-up after the invitation letter. Most participants selected web education (88.5%) as an alternative to speaking with a GC, but some did not complete or receive results. Knowledge increased significantly from baseline to other time points with no significant differences between those who received web versus GC education. There were no significant increases in distress between web and GC education.

CONCLUSION

Interest in web-based predisclosure education for return of genetic research results was high although it did not increase uptake of results. We found no negative patient-reported outcomes with web education, suggesting that it is a viable alternative delivery model for reducing burdens and costs of returning genetic research results. Attention to attrition and lower uptake of results among Black participants and those with less formal education are important areas for future research.

NCCN Guidelines® Insights: Genetic/Familial High-Risk Assessment: Breast, Ovarian, and Pancreatic, Version 2.2024

The NCCN Guidelines for Genetic/Familial High-Risk Assessment: Breast, Ovarian, and Pancreatic focus primarily on assessment of pathogenic/likely pathogenic (P/LP) variants associated with increased risk of breast, ovarian, pancreatic, and prostate cancer, including BRCA1, BRCA2, CDH1, PALB2, PTEN, and TP53, and recommended approaches to genetic counseling/testing and care strategies in individuals with these P/LP variants. These NCCN Guidelines Insights summarize important updates regarding: (1) a new section for transgender, nonbinary and gender diverse people who have a hereditary predisposition to cancer focused on risk reduction strategies for ovarian cancer, uterine cancer, prostate cancer, and breast cancer; and (2) testing criteria and management associated with TP53 P/LP variants and Li-Fraumeni syndrome.

Biallelic BRCA Loss and Homologous Recombination Deficiency in Nonbreast/Ovarian Tumors in Germline BRCA1/2 Carriers

PURPOSE

Breast and ovarian tumors in germline BRCA1/2 carriers undergo allele-specific loss of heterozygosity, resulting in homologous recombination deficiency (HRD) and sensitivity to poly-ADP-ribose polymerase (PARP) inhibitors. This study investigated whether biallelic loss and HRD also occur in primary nonbreast/ovarian tumors that arise in germline BRCA1/2 carriers.

METHODS

A clinically ascertained cohort of BRCA1/2 carriers with a primary nonbreast/ovarian cancer was identified, including canonical (prostate and pancreatic cancers) and noncanonical (all other) tumor types. Whole-exome sequencing or clinical sequencing results (n = 45) were analyzed. A pan-cancer analysis of nonbreast/ovarian primary tumors from germline BRCA1/2 carriers from The Cancer Genome Atlas (TCGA, n = 73) was used as a validation cohort.

RESULTS

Ages of nonbreast/ovarian cancer diagnosis in germline BRCA1/2 carriers were similar to controls for the majority of cancer types. Nine of 45 (20%) primary nonbreast/ovarian tumors from germline BRCA1/2 carriers had biallelic loss of BRCA1/2 in the clinical cohort, and 23 of 73 (32%) in the TCGA cohort. In the combined cohort, 35% and 27% of primary canonical and noncanonical BRCA tumor types, respectively, had biallelic loss. High HRD scores (HRDex > 42) were detected in 81% of tumors with biallelic BRCA loss compared with 22% (P < .001) of tumors without biallelic BRCA loss. No differences in genomic profile, including mutational signatures, mutation spectrum, tumor mutational burden, or microsatellite instability, were found in primary nonbreast/ovarian tumors with or without biallelic BRCA1/2 loss.

CONCLUSION

A proportion of noncanonical primary tumors have biallelic loss and evidence of HRD. Our data suggest that assessment of biallelic loss and HRD could supplement identification of germline BRCA1/2 mutations in selection of patients for platinum or PARP inhibitor therapy.

Combination ATR (ceralasertib) and PARP (olaparib) Inhibitor (CAPRI) Trial in Acquired PARP Inhibitor-Resistant Homologous Recombination-Deficient Ovarian Cancer

PURPOSE

Addition of ataxia telangiectasia and Rad3-related kinase inhibitors (ATRi) to PARP inhibitors (PARPi) overcomes PARPi resistance in high-grade serous ovarian cancer (HGSOC) cell and mouse models. We present the results of an investigator-initiated study of combination PARPi (olaparib) and ATRi (ceralasertib) in patients with acquired PARPi-resistant HGSOC.

PATIENTS AND METHODS

Eligible patients had recurrent, platinum-sensitive BRCA1/2 mutated or homologous recombination (HR)-deficient (HRD) HGSOC and clinically benefited from PARPi (response by imaging/CA-125 or duration of maintenance therapy; > 12 months first-line or > 6 months ≥ second-line) before progression. No intervening chemotherapy was permitted. Patients received olaparib 300 mg twice daily and ceralasertib 160 mg daily on days 1 to 7 of a 28-day cycle. Primary objectives were safety and objective response rate (ORR).

RESULTS

Thirteen patients enrolled were evaluable for safety and 12 for efficacy; 62% (n = 8) had germline BRCA1/2 mutations, 23% (n = 3) somatic BRCA1/2 mutations, and 15% (n = 2) tumors with positive HRD assay. Prior PARPi indication was treatment for recurrence (54%, n = 7), second-line maintenance (38%, n = 5) and first-line treatment with carboplatin/paclitaxel (8%, n = 1). There were 6 partial responses yielding an ORR of 50% (95% confidence interval, 0.15-0.72). Median treatment duration was 8 cycles (range 4-23+). Grade (G) 3/4 toxicities were 38% (n = 5); 15% (n = 2) G3 anemia, 23% (n = 3) G3 thrombocytopenia, 8% (n = 1) G4 neutropenia. Four patients required dose reductions. No patient discontinued treatment due to toxicity.

CONCLUSIONS

Combination olaparib and ceralasertib is tolerable and shows activity in HR-deficient platinum-sensitive recurrent HGSOC that benefited and then progressed with PARPi as the penultimate regimen. These data suggest that ceralasertib resensitizes PARPi-resistant HGSOCs to olaparib, warranting further investigation.

Functional and Clinical Characterization of Variants of Uncertain Significance Identifies a Hotspot for Inactivating Missense Variants in RAD51C

Pathogenic protein-truncating variants of RAD51C, which plays an integral role in promoting DNA damage repair, increase the risk of breast and ovarian cancer. A large number of RAD51C missense variants of uncertain significance (VUS) have been identified, but the effects of the majority of these variants on RAD51C function and cancer predisposition have not been established. Here, analysis of 173 missense variants by a homology-directed repair (HDR) assay in reconstituted RAD51C-/- cells identified 30 nonfunctional (deleterious) variants, including 18 in a hotspot within the ATP-binding region. The deleterious variants conferred sensitivity to cisplatin and olaparib and disrupted formation of RAD51C/XRCC3 and RAD51B/RAD51C/RAD51D/XRCC2 complexes. Computational analysis indicated the deleterious variant effects were consistent with structural effects on ATP-binding to RAD51C. A subset of the variants displayed similar effects on RAD51C activity in reconstituted human RAD51C-depleted cancer cells. Case-control association studies of deleterious variants in women with breast and ovarian cancer and noncancer controls showed associations with moderate breast cancer risk [OR, 3.92; 95% confidence interval (95% CI), 2.18-7.59] and high ovarian cancer risk (OR, 14.8; 95% CI, 7.71-30.36), similar to protein-truncating variants. This functional data supports the clinical classification of inactivating RAD51C missense variants as pathogenic or likely pathogenic, which may improve the clinical management of variant carriers.

SIGNIFICANCE

Functional analysis of the impact of a large number of missense variants on RAD51C function provides insight into RAD51C activity and information for classification of the cancer relevance of RAD51C variants.

Development of an Electronic Health Record-Based Clinical Decision Support Tool for Patients With Lynch Syndrome

PURPOSE

To develop an electronic health record (EHR)-based clinical decision support (CDS) tool to promote guideline-recommended cancer risk management among patients with Lynch syndrome (LS), an inherited cancer syndrome that confers an increased risk of colorectal and other cancer types.

MATERIALS AND METHODS

We conducted a cross-sectional study to determine the baseline prevalence and predictors of guideline-recommended colonic surveillance and annual genetics program visits among patients with LS. Multivariable log-binomial regressions estimated prevalence ratios (PRs) of cancer risk management adherence by baseline sociodemographic and clinical characteristics. These analyses provided rationale for the development of an EHR-based CDS tool to support patients and clinicians with LS-related endoscopic surveillance and annual genetics program visits. The CDS leverages an EHR platform linking discrete genetic data to LS Genomic Indicators, in turn driving downstream clinician- and patient-facing CDS.

RESULTS

Among 323 patients with LS, cross-sectional adherence to colonic surveillance and annual genetics program visits was 69.3% and 55.4%, respectively. Patients with recent electronic patient portal use were more likely to be adherent to colonic surveillance (PR, 1.67; 95% CI, 1.11 to 2.52). Patients more recently diagnosed with LS were more likely to be adherent to annual genetics program visits (PR, 0.58; 95% CI, 0.44 to 0.76 for 2-4 years; PR, 0.62; 95% CI, 0.51 to 0.75 for ≥4 compared with <2 years). Our EHR-based CDS tool is now active for 421 patients with LS throughout our health system.

CONCLUSION

We have successfully developed an EHR-based CDS tool to promote guideline-recommended cancer risk management among patients with LS.

Measuring high-risk parents' opinions about direct-to-consumer genetic testing for adult-onset inherited cancer syndromes in their adolescent and young adult children

Neither direct-to-consumer (DTC) genetic testing nor predictive genetic testing for adult-onset conditions is recommended for minor children due to ethical concerns and low clinical utility. However, parents with pathogenic variants (PVs) in disease-causing genes may be interested in pursuing genetic testing that includes the familial PV for their children. The Pediatric Testing Attitudes Scale (P-TAS) was previously developed to examine high-risk parents' opinions about pediatric BRCA genetic testing for adult-onset breast/ovarian cancer. Here, the psychometric properties of the P-TAS were examined in a new sample of N = 126 parents (M age = 47.2 years) with PVs in a more complete set of cancer risk genes represented on DTC panel tests. The mean score on the P-TAS was 44 out of a maximum score of 60, indicating that a majority of parents generally held favorable opinions about testing their children for adult-onset inherited cancer syndromes. The internal consistency of the full scale was high (α = 0.91). A factor analysis identified two-component scales, labeled Attitudes and Beliefs (α = 0.93) and Decision Making and Communication (α = 0.83). In a multivariable regression model, P-TAS co-factors accounted for 34% of variance in parental opinions, including the frequency of prior family communication about cancer and the likelihood of utilizing DTC genetic testing with children (R2  = 0.34, p < 0.001). Results suggest that the P-TAS remains a reliable measure to assess high-risk parents' opinions about pediatric DTC genetic testing for adult-onset conditions, with promising validity. Applications of the P-TAS include informing genetic counseling practice, pediatric medical care, and policy guidelines surrounding DTC genetic testing.

Identification of BRCA1/2 mutation female carriers using circulating microRNA profiles

Identifying germline BRCA1/2 mutation carriers is vital for reducing their risk of breast and ovarian cancer. To derive a serum miRNA-based diagnostic test we used samples from 653 healthy women from six international cohorts, including 350 (53.6%) with BRCA1/2 mutations and 303 (46.4%) BRCA1/2 wild-type. All individuals were cancer-free before and at least 12 months after sampling. RNA-sequencing followed by differential expression analysis identified 19 miRNAs significantly associated with BRCA mutations, 10 of which were ultimately used for classification: hsa-miR-20b-5p, hsa-miR-19b-3p, hsa-let-7b-5p, hsa-miR-320b, hsa-miR-139-3p, hsa-miR-30d-5p, hsa-miR-17-5p, hsa-miR-182-5p, hsa-miR-421, hsa-miR-375-3p. The final logistic regression model achieved area under the receiver operating characteristic curve 0.89 (95% CI: 0.87-0.93), 93.88% sensitivity and 80.72% specificity in an independent validation cohort. Mutated gene, menopausal status or having preemptive oophorectomy did not affect classification performance. Circulating microRNAs may be used to identify BRCA1/2 mutations in patients of high risk of cancer, offering an opportunity to reduce screening costs.

Olaparib and durvalumab in patients with relapsed small cell lung cancer (MEDIOLA): An open-label, multicenter, phase 1/2, basket study

INTRODUCTION

Preclinical studies have demonstrated increased efficacy with combined DNA damage response inhibition and immune checkpoint blockade compared with either alone. We assessed olaparib in combination with durvalumab in patients with relapsed small cell lung cancer (SCLC).

METHODS

Patients with previously treated limited or extensive-stage SCLC received oral olaparib 300 mg twice daily, as run-in for 4 weeks, then with durvalumab (1500 mg intravenously every 4 weeks) until disease progression. Primary endpoints were safety, tolerability, and 12-week disease control rate (DCR). Secondary endpoints included 28-week DCR, objective response rate (ORR), duration of response, progression-free survival, overall survival, change in tumor size, and programmed death-ligand 1 (PD-L1) expression subgroup analyses.

RESULTS

Forty patients were enrolled and analyzed for safety; 38 were analyzed for efficacy. Eleven patients (28.9% [90% confidence interval (CI), 17.2-43.3]) had disease control at 12 weeks. ORR was 10.5% (95% CI, 2.9-24.8). Median progression-free and overall survival were 2.4 (95% CI, 0.9-3.0)months and 7.6(95% CI, 5.6-8.8)months, respectively. The most common adverse events (≥40.0%) were anemia, nausea, and fatigue. Grade ≥ 3 adverse events occurred in 32 patients (80.0%). PD-L1 levels, tumor mutational burden, and other genetic mutations were evaluated, but no significant correlations with clinical outcomes wereobserved.

CONCLUSIONS

Tolerability of olaparib with durvalumab was consistent with the safety profile of each agent alone. Although the 12-week DCR did not meet the prespecified target (60%), four patients responded, and median overall survival was promising for a pretreated SCLC population. Further analyses are required to identify patients most likely to benefit from this treatment approach.

Ovarian cancer pathology characteristics as predictors of variant pathogenicity in BRCA1 and BRCA2

BACKGROUND

The distribution of ovarian tumour characteristics differs between germline BRCA1 and BRCA2 pathogenic variant carriers and non-carriers. In this study, we assessed the utility of ovarian tumour characteristics as predictors of BRCA1 and BRCA2 variant pathogenicity, for application using the American College of Medical Genetics and the Association for Molecular Pathology (ACMG/AMP) variant classification system.

METHODS

Data for 10,373 ovarian cancer cases, including carriers and non-carriers of BRCA1 or BRCA2 pathogenic variants, were collected from unpublished international cohorts and consortia and published studies. Likelihood ratios (LR) were calculated for the association of ovarian cancer histology and other characteristics, with BRCA1 and BRCA2 variant pathogenicity. Estimates were aligned to ACMG/AMP code strengths (supporting, moderate, strong).

RESULTS

No histological subtype provided informative ACMG/AMP evidence in favour of BRCA1 and BRCA2 variant pathogenicity. Evidence against variant pathogenicity was estimated for the mucinous and clear cell histologies (supporting) and borderline cases (moderate). Refined associations are provided according to tumour grade, invasion and age at diagnosis.

CONCLUSIONS

We provide detailed estimates for predicting BRCA1 and BRCA2 variant pathogenicity based on ovarian tumour characteristics. This evidence can be combined with other variant information under the ACMG/AMP classification system, to improve classification and carrier clinical management.

PREDICT validity for prognosis of breast cancer patients with pathogenic BRCA1/2 variants

We assessed the PREDICT v 2.2 for prognosis of breast cancer patients with pathogenic germline BRCA1 and BRCA2 variants, using follow-up data from 5453 BRCA1/2 carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) and the Breast Cancer Association Consortium (BCAC). PREDICT for estrogen receptor (ER)-negative breast cancer had modest discrimination for BRCA1 carrier patients overall (Gönen & Heller unbiased concordance 0.65 in CIMBA, 0.64 in BCAC), but it distinguished clearly the high-mortality group from lower risk categories. In an analysis of low to high risk categories by PREDICT score percentiles, the observed mortality was consistently lower than the expected mortality, but the confidence intervals always included the calibration slope. Altogether, our results encourage the use of the PREDICT ER-negative model in management of breast cancer patients with germline BRCA1 variants. For the PREDICT ER-positive model, the discrimination was slightly lower in BRCA2 variant carriers (concordance 0.60 in CIMBA, 0.65 in BCAC). Especially, inclusion of the tumor grade distorted the prognostic estimates. The breast cancer mortality of BRCA2 carriers was underestimated at the low end of the PREDICT score distribution, whereas at the high end, the mortality was overestimated. These data suggest that BRCA2 status should also be taken into consideration with tumor characteristics, when estimating the prognosis of ER-positive breast cancer patients.

OlympiAD extended follow-up for overall survival and safety: Olaparib versus chemotherapy treatment of physician's choice in patients with a germline BRCA mutation and HER2-negative metastatic breast cancer

BACKGROUND

In the Phase III OlympiAD study, olaparib significantly prolonged progression-free survival versus chemotherapy treatment of physician's choice (TPC) in patients with germline BRCA-mutated (gBRCAm), human epidermal growth factor receptor 2-negative metastatic breast cancer (mBC). In the final pre-specified analysis (64% maturity), median overall survival (OS) was 19.3 months for olaparib and 17.1 months for TPC (P = 0.513). Post-hoc extended follow-up, 25.7 months longer than previously reported for OS, is reported.

PATIENTS AND METHODS

Patients with gBRCAm, human epidermal growth factor receptor 2-negative mBC, who had received ≤2 lines of chemotherapy for metastatic disease, were randomised 2:1 to olaparib (300 mg bid) or TPC. During extended follow-up, OS was analysed every 6 months using the stratified log-rank test (overall population) and Cox proportional hazards model (pre-specified subgroups).

RESULTS

In the overall population (302 patients; 76.8% maturity), median OS was 19.3 months for olaparib and 17.1 months for TPC (hazard ratio 0.89, 95% confidence interval 0.67-1.18); median follow-up was 18.9 and 15.5 months, respectively. Three-year survival was 27.9% for olaparib versus 21.2% for TPC. With olaparib, 8.8% of patients received study treatment for ≥3 years versus none with TPC. In first-line mBC, median OS was longer for olaparib than TPC (22.6 versus 14.7 months; hazard ratio 0.55, 95% confidence interval 0.33-0.95) and 3-year survival was 40.8% for olaparib versus 12.8% for TPC. No new serious adverse events related to olaparib were observed.

CONCLUSIONS

OS was consistent with previous analyses from OlympiAD. These findings support the possibility of meaningful long-term survival benefit with olaparib, particularly in first-line mBC.

Clinical Impact of a Rapid Genetic Testing Model for Advanced Prostate Cancer Patients

PURPOSE

Genetic testing may alter clinical management for individuals with metastatic prostate cancer by identifying additional therapies. Traditional counseling models are unlikely to enable time-sensitive therapeutic decision-making. This study aimed to determine the feasibility and clinical impact of an alternative hereditary genetic testing model.

MATERIALS AND METHODS

As part of a multicenter, single-arm prospective trial, individuals with advanced prostate cancer were referred by their oncologist for testing of 14 genes associated with hereditary prostate cancer. Pretest education (brochure and video) was provided in the oncology clinic. Questionnaires assessing participant satisfaction with both pretest education and decision to undergo genetic testing were collected. A genetic counselor contacted participants by phone to obtain family history and discuss results. Medical records were queried to determine whether a change in clinical management was discussed.

RESULTS

Of 501 participants consented to germline analysis, 51 (10.2%) had at least 1 pathogenic/likely pathogenic variant. Change in treatment was discussed with 22/48 (45.8%) of eligible participants who tested positive. Feasibility of this model was assessed by participant satisfaction and turnaround time. Average±SD satisfaction with the pretest education (15.5±2.2, 4-20 scale) and with the decision to undergo genetic testing (17.1±2.9, 4-20 scale) were both high. Results were returned 20 days (median) after sample collection.

CONCLUSIONS

Oncologist-initiated germline genetic testing in collaboration with a genetic counselor is a feasible approach to testing advanced prostate cancer patients with impactful clinical actionability. The testing model and educational material serve as resources to clinicians treating prostate cancer patients.

Abstract 1183: Mutation type and location in breast cancer susceptibility genes are associated with differential risk in the general population

Two recent studies have defined population-based risk of breast cancer (BC) due to pathogenic variants (PVs) in well-established BC susceptibility genes. Prior studies in high-risk BC cohorts identified variable BC risks based on the position and type of mutation in BRCA1 and BRCA2, and based on the type of mutation in ATM, CHEK2, and PALB2. Whether this variability holds true in the general population has not been evaluated. To determine the BC risks associated with mutations of different types and in different locations in BC susceptibility genes in the general population, we carried out case-control analyses of 32247 cases and 32544 controls in the CARRIERS study, including 12 US population-based studies, and case-control analyses, subset to mutation carriers. We used age-adjusted logistic regression to estimate odds ratios (OR), relative OR (rOR), and 95% confidence intervals (CI) for PVs in BRCA1, BRCA2, ATM, CHEK2, and PALB2. ORs were estimated using the full population of mutation carriers and noncarriers while rORs were estimated within subsets of individual gene mutation carriers. We identified 273 BRCA1, 421 BRCA2, 253 ATM, 351 CHEK2, and 148 PALB2 in women with BC and 35 BRCA1, 84 BRCA2, 139 ATM, 139 CHEK2, and 38 PALB2 variant carriers in those without BC. For BRCA1, we did not find differences in risk by mutation type or location. However, variants leading to nonsense mediated decay (NMD) predicted to have re-initiation at p.M128 had a non-statistical 3-fold higher risk for BC compared to those leading to NMD without re-initiation (rOR 3.1, 0.99-13.52, p = 0.0826). BRCA2 loss of function (LoF) mutations in exons 1-10 had a higher BC risk compared to LoF mutations in the exon 11 (rOR 2.7, 1.1-7.9, p=0.048) ovarian cancer cluster region (OCCR). We did not detect any differences in risk by mutation type or location in ATM, CHEK2, or PALB2. CHEK2 missense variants p.I157T (rOR 0.5, 0.4-0.7, p &lt;0.001) and p.T476M (rOR 0.5, 0.3 - 0.8, p=0.005) were associated with lower BC risk relative to CHEK2 c.1100delC (OR 2.5, 2.0-3.3, p&lt;0.001). The CHEK2 c.444+1G&gt;A splicing variant was associated with highest BC risk among common CHEK2 variants (OR 4.2, 1.9-10.5, p&lt;0.001), but was not statistically significantly different from c.1100delC (rOR 1.7, 0.8-4.3, p=0.230). In summary, we identified a higher BC risk for LoF variants in BRCA2, lower risk for CHEK2 missense mutations, and non-statistical higher risk for NMD/re-initiation BRCA1 variants and CHEK2 c.444+1G&gt;A in this population-based study. Despite the large numbers included in the overall CARRIERS study, the number of PV carriers was relatively small, which may have limited the detection of associations. Nonetheless, we were able to detect genotype-risk associations that have implications for counseling women about their BC risk, and certainly for the development of individualized risks.

Citation Format: Mwangala P. Akamandisa, Nicholas Boddicker, Chunling Hu, Siddhartha Yadav, Jeffrey N. Weitzel, Peter Kraft, Susan M. Domchek, Fergus J. Couch, Katherine L. Nathanson, for the CARRIERS Consortium . Mutation type and location in breast cancer susceptibility genes are associated with differential risk in the general population [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1183.

Summary of the experiences, knowledge, medical management, and family communication of monoallelic MUTYH carriers

Germline genetic testing for inherited cancer risk is increasingly being performed with multigene panel testing with MUTYH often included on colorectal cancer- and polyposis-focused panels, as well as on broader pan-cancer panels. With up to 1%-2% of the general population being monoallelic MUTYH carriers, pathogenic/likely pathogenic (P/LP) variants in MUTYH are one of the most common findings on multigene cancer panels. However, little is known about patient experience and understanding of monoallelic MUTYH P/LP variants, nor whether such findings influence medical management recommendations and familial communication, which this study aims to better understand. Monoallelic P/LP MUTYH carriers were recruited from the Prospective Registry of Multiplex Testing (PROMPT) and completed a cross-sectional self-report survey on sociodemographic characteristics, medical and family history, experiences with MUTYH genetic testing, genetics and MUTYH knowledge, perceived cancer risk, and familial communication. Of 115 eligible PROMPT participants, 49 (43%) completed the survey who were primarily female (94%), white (96%), had a history of cancer (61%), and a median age of 51.4 years. Most participants (61%) reported satisfaction with how their healthcare provider managed their genetic test result and care, and 65% of survey participants reported their provider recommended colonoscopy based on their genetic test results. Participants' responses also reflected variable levels of knowledge regarding cancer risks and screening recommendations for MUTYH carriers. The majority (98%) of participants shared their genetic test results with at least some of their relatives; however, only 13% of eligible relatives reportedly underwent cascade testing. Taken together, this study provides needed insight into the overall experiences of monoallelic MUTYH carriers and highlights numerous areas for improvement in clinician education, communication, and management of these individuals.

Nationwide Trends and Determinants of Germline BRCA1/2 Testing in Patients With Breast and Ovarian Cancer

BACKGROUND

Germline genetic testing (GT) for BRCA1/2 is instrumental in identifying patients with breast and ovarian cancers who are eligible for PARP inhibitors (PARPi). Little is known about recent trends and determinants of GT since PARPi were approved for these patients.

PATIENTS AND METHODS

We performed a retrospective cohort study of patients in a nationwide electronic health record (EHR)-derived oncology-specific database with the following GT eligibility criteria: breast cancer diagnosed at age ≤45 years, triple-negative breast cancer diagnosed at age ≤60 years, male breast cancer, or ovarian cancer. GT within 1 year of diagnosis was assessed and stratified by tumor type. Multivariable log-binomial regressions estimated adjusted relative risks (RRs) of GT by patient and tumor characteristics.

RESULTS

Among 2,982 eligible patients with breast cancer, 56.4% underwent GT between January 2011 and March 2020, with a significant increase in GT over time (RR, 1.08; 95% CI, 1.05-1.11, for each year), independent of when PARPi were approved for BRCA1/2-mutated metastatic breast cancer in January 2018. In multivariable analyses, older age (RR, 0.93; 95% CI, 0.90-0.96, for every 5 years) and Medicare coverage (RR, 0.69; 95% CI, 0.49-0.96 vs commercial insurance) were associated with less GT. Among 5,563 eligible patients with ovarian cancer, 35.4% underwent GT between January 2011 and March 2020, with a significant increase in GT over time (RR, 1.11; 95% CI, 1.07-1.14, for each year) that accelerated after approval of PARPi for BRCA1/2-mutated, chemotherapy-refractory ovarian cancer in December 2014 (RR, 1.42; 95% CI, 1.19-1.70). Older age (RR, 0.95; 95% CI, 0.93-0.97, for every 5 years) and Black or African American race (RR, 0.80; 95% CI, 0.65-0.98 vs White race) were associated with less GT.

CONCLUSIONS

GT remains underutilized nationwide among patients with breast and ovarian cancers. Although GT has increased over time, significant disparities by age, race, and insurance status persist. Additional work is needed to design, implement, and evaluate strategies to ensure that all eligible patients receive GT.

Olaparib efficacy in patients with germline BRCA ‐ mutated, HER2 ‐negative metastatic breast cancer: subgroup analyses from the phase III OlympiAD trial

In the primary analysis of the phase III OlympiAD trial, olaparib significantly prolonged progression-free survival (PFS) vs chemotherapy treatment of physician's choice (TPC) in patients with germline BRCA-mutated (gBRCAm), HER2-negative metastatic breast cancer (mBC). We report subgroup analyses for the final analysis at a median OS follow-up of 18.9 months (olaparib) and 15.5 months (TPC). Patients (N = 302) with gBRCAm, HER2-negative mBC and ≤2 previous lines of chemotherapy for mBC were randomized 2:1 to open-label olaparib (300 mg twice daily) or TPC. All subgroup analyses were prespecified except site of metastases. Investigator-assessed median PFS was 8.0 months (95% confidence interval [CI] 5.8-8.4; 176/205 events) for olaparib and 3.8 months (95% CI 2.8-4.2; 83/97 events) for TPC (hazard ratio 0.51, 95% CI 0.39-0.66). In subgroup analyses, median PFS hazard ratios (95% CI) favored olaparib: hormone receptor status (triple-negative: 0.47, 0.32-0.69; hormone receptor-positive: 0.52, 0.36-0.75); gBRCAm (BRCA1: 0.49, 0.35-0.71; BRCA2: 0.49, 0.33-0.74); site of metastases (visceral/CNS: 0.53, 0.40-0.71; non-visceral: 0.45, 0.23-0.98); prior chemotherapy for mBC (yes: 0.51, 0.38-0.70; no: 0.49, 0.30-0.82); prior platinum-based chemotherapy for BC (yes: 0.49, 0.30-0.83; no: 0.50, 0.37-0.69); progressive disease at randomization (yes: 0.48, 0.35-0.65; no: 0.61, 0.36-1.07). Investigator-assessed objective response rates were higher across all subgroups with olaparib (35-68%) vs TPC (5-40%). Global health status/health-related quality of life increased in all subgroups with olaparib vs decreased/no change with TPC. These data confirm the consistency of olaparib benefit across patient subgroups in OlympiAD.

Contralateral Breast Cancer Risk Among Carriers of Germline Pathogenic Variants in ATM, BRCA1, BRCA2, CHEK2, and PALB2

PURPOSE

To estimate the risk of contralateral breast cancer (CBC) among women with germline pathogenic variants (PVs) in ATM, BRCA1, BRCA2, CHEK2, and PALB2.

METHODS

The study population included 15,104 prospectively followed women within the CARRIERS study treated with ipsilateral surgery for invasive breast cancer. The risk of CBC was estimated for PV carriers in each gene compared with women without PVs in a multivariate proportional hazard regression analysis accounting for the competing risk of death and adjusting for patient and tumor characteristics. The primary analyses focused on the overall cohort and on women from the general population. Secondary analyses examined associations by race/ethnicity, age at primary breast cancer diagnosis, menopausal status, and tumor estrogen receptor (ER) status.

RESULTS

Germline BRCA1, BRCA2, and CHEK2 PV carriers with breast cancer were at significantly elevated risk (hazard ratio > 1.9) of CBC, whereas only the PALB2 PV carriers with ER-negative breast cancer had elevated risks (hazard ratio, 2.9). By contrast, ATM PV carriers did not have significantly increased CBC risks. African American PV carriers had similarly elevated risks of CBC as non-Hispanic White PV carriers. Among premenopausal women, the 10-year cumulative incidence of CBC was estimated to be 33% for BRCA1, 27% for BRCA2, and 13% for CHEK2 PV carriers with breast cancer and 35% for PALB2 PV carriers with ER-negative breast cancer. The 10-year cumulative incidence of CBC among postmenopausal PV carriers was 12% for BRCA1, 9% for BRCA2, and 4% for CHEK2.

CONCLUSION

Women diagnosed with breast cancer and known to carry germline PVs in BRCA1, BRCA2, CHEK2, or PALB2 are at substantially increased risk of CBC and may benefit from enhanced surveillance and risk reduction strategies.

A phase II single-arm trial of niraparib in platinum-sensitive metastatic castration-resistant prostate cancer with DNA repair defects (PLATPARP)

TPS291

Background: Platinum-based chemotherapy, either as monotherapy or in combination with taxanes, is increasingly used for patients with metastatic castration-resistant prostate cancer (mCRPC) harboring germline and/or somatic homologous recombination repair gene mutations (HRRm). However, clinical responses with platinum-based therapy are often of limited duration and limited by cumulative toxicities. The PARP inhibitor (PARPi) olaparib is approved for the treatment of mCRPC patients with pathogenic HRRm after progression on enzalutamide or abiraterone. Importantly, sensitivity to platinum-based chemotherapy may predict improved clinical outcomes with PARPi, and ‘maintenance’ PARPi strategies are routinely used in patients with advanced ovarian and pancreatic malignancies with HRRm with initial clinical response to platinum chemotherapy. We hypothesize that maintenance niraparib, a PARPi with demonstrated activity in mCRPC with HRRm, will prolong clinical responses to platinum-based chemotherapy with acceptable toxicity in mCRPC patients harboring germline and/or somatic HRRm. Methods: We are conducting an open-label, single-arm, phase II study to evaluate the clinical benefit of maintenance niraparib in biomarker-defined, platinum-sensitive mCRPC patients. Eligible subjects harbor a pathogenic germline and/or somatic mutation in BRCA1/2, ATM, FANCA, CDK12, RAD51B, RAD54L, PALB2, CHEK2, HDAC2, or BRIP1 and have received at least 3 cycles (or minimum 9 weeks) of platinum-based chemotherapy for the treatment of mCRPC per investigator discretion. Following ³4 weeks since completion of chemotherapy, subjects without evidence of clinical or radiographic disease progression receive investigational treatment with maintenance niraparib (starting dose 200 mg daily). The primary objective is an improvement in 6 month PFS rate (PFS6) (H0: PFS6 rate 25%; H1: PFS6 rate 50%; power 0.77 with one-sided α = 0.05). Serial plasma samples are obtained for correlative analyses of markers of response and/or resistance to maintenance niraparib. Eight of a planned total of 18 subjects have enrolled (N=3 germline BRCA2; N=2 somatic BRCA2; N=1 germline PALB2; N=1 germline ATM; N=1 germline CHEK2). This study incorporates a novel, combined genetic and clinical patient-selection approach for PARPi therapy to optimize clinical outcomes. Clinical trial information: NCT04288687 .

The identification of reversion mutations in patients with advanced pancreatic cancer and germline or somatic BRCA or PALB2 variants who were treated with maintenance rucaparib

734

Background: Maintenance PARP inhibition (PARPi) extends progression-free survival and improves quality of life for patients (pts) with advanced, platinum-sensitive pancreatic cancer (PC) and BRCA or PALB2 variants. However, most will experience progression. PARPi resistance mechanisms are poorly defined in PC. Cell-free (cf)DNA analysis can detect some known classes of resistance mechanisms, like reversion mutations, and other potentially prognostic and predictive genomic features. Methods: Pts with advanced, platinum-sensitive pancreatic cancer and pathogenic germline or somatic BRCA1, BRCA2, or PALB2 variants were treated with maintenance rucaparib on clinical trial. cfDNA was collected at baseline and progression and analyzed with the GuardantOMNI 500-gene liquid biopsy. Time to event analysis was performed from index date of enrollment until endpoint (PFS, OS, and PFS2). Associations were tested by the log-rank test with adjustment. Results: The trial enrolled 42 pts, of whom 31 have progressed. cfDNA was available for 41 pts at baseline and 30 pts at progression; 88% had baseline detectable cfDNA. Two pts had baseline reversion mutations, 5 had new reversion mutations at progression. Of 21 pts who had tissue NGS, 17 pts had a KRAS variant in the tumor, 12 of whom had detectable cfDNA at either baseline or progression. Of the 41 patients with cfDNA samples, 10 pts had baseline KRAS mutations detected in plasma; an additional 10 pts had a detectable plasma KRAS mutation at progression. Outcomes are shown. Of those who had progressed, pts with acquired reversion mutations had shorter OS (p<0.001) and PFS (p = 0.018) on rucaparib than those without reversion mutations. Of those who received chemo after progression (n=23), PFS2 was shorter for pts with acquired reversions compared to those with no reversions (p = 0.038). KRAS mutation detection at baseline was observed with higher overall somatic allele fraction in cfDNA and a trend toward shorter PFS and OS. Conclusions: Acquired reversion mutations were infrequent but associated with worse outcomes. Other causes of resistance may be dominant. Detection of KRAS mutation in the peripheral blood may be associated with disease burden and clinical outcome. [Table: see text]

APOLLO: A randomized phase II double-blind study of olaparib versus placebo following curative intent therapy in patients with resected pancreatic cancer and a pathogenic BRCA1, BRCA2 or PALB2 mutation—ECOG-ACRIN EA2192

TPS763

Background: A meaningful subset of PDAC is characterized by a homologous recombination deficiency (HRD). The most well-defined patients within this group are those with pathogenic variants in BRCA1, BRCA2 and PALB2. In the metastatic setting, PARP inhibitor maintenance provides a progression-free survival benefit after a period of platinum based chemotherapy1,2, but the role of PARP inhibitors in the curative intent setting is undefined. The OlympiA study established one year of olaparib as the standard of care for patients with BRCA-related, early stage breast cancer who completed all other curative-intent treatment3. Therefore, we have designed a randomized, phase II double-blind study of one year of olaparib vs placebo in patients with pancreatic cancer and a germline or somatic variant in BRCA or PALB2 who have completed all curative intent therapy. Methods: We have enrolled and treated 23 of 152 planned patients on study NCT 04858334/EA2192. Eligibility criteria include: a pathogenic germline or somatic variant in BRCA1, BRCA2 or PALB2 as determined by local laboratory (central review required); completion of curative-intent resection and ≥ three months of multi-agent chemotherapy; no evidence of recurrent disease. At enrollment, patients must be within 12 weeks of their last anti-cancer intervention. Patients are randomized 2:1 to receive oral olaparib 300 mg twice daily or placebo for 12 28-day cycles. The primary endpoint is relapse-free survival. Overall survival is a secondary endpoint. Tumor tissue, fecal material (for microbiome analysis) and serial ctDNA samples are being collected. 1.Golan T, Locker GY, Kindler HL: N Engl J Med 381:1492-1493, 2019. 2. Reiss KA, Mick R, O'Hara MH, et al: J Clin Oncol 39:2497-2505, 2021. 3. Tutt ANJ, Garber JE, Geyer CE, Jr.: N Engl J Med 385:1440, 2021. Clinical trial information: NCT04858334 .

Avelumab Plus Talazoparib in Patients With BRCA1/2- or ATM-Altered Advanced Solid Tumors: Results From JAVELIN BRCA/ATM, an Open-Label, Multicenter, Phase 2b, Tumor-Agnostic Trial

Importance

Nonclinical studies suggest that the combination of poly(ADP-ribose) polymerase and programmed cell death 1/programmed cell death-ligand 1 inhibitors has enhanced antitumor activity; however, the patient populations that may benefit from this combination have not been identified.

Objective

To evaluate whether the combination of avelumab and talazoparib is effective in patients with pathogenic BRCA1/2 or ATM alterations, regardless of tumor type.

Design, Setting, and Participants

In this pan-cancer tumor-agnostic phase 2b nonrandomized controlled trial, patients with advanced BRCA1/2-altered or ATM-altered solid tumors were enrolled into 2 respective parallel cohorts. The study was conducted from July 2, 2018, to April 12, 2020, at 42 institutions in 9 countries.

Interventions

Patients received 800 mg of avelumab every 2 weeks and 1 mg of talazoparib once daily.

Main Outcomes and Measures

The primary end point was confirmed objective response (OR) per RECIST 1.1 by blinded independent central review.

Results

A total of 200 patients (median [range] age, 59.0 [26.0-89.0] years; 132 [66.0%] women; 15 [7.5%] Asian, 11 [5.5%] African American, and 154 [77.0%] White participants) were enrolled: 159 (79.5%) in the BRCA1/2 cohort and 41 (20.5%) in the ATM cohort. The confirmed OR rate was 26.4% (42 patients, including 9 complete responses [5.7%]) in the BRCA1/2 cohort and 4.9% (2 patients) in the ATM cohort. In the BRCA1/2 cohort, responses were more frequent (OR rate, 30.3%; 95% CI, 22.2%-39.3%, including 8 complete responses [6.7%]) and more durable (median duration of response: 10.9 months [95% CI, 6.2 months to not estimable]) in tumor types associated with increased heritable cancer risk (ie, BRCA1/2-associated cancer types, such as ovarian, breast, prostate, and pancreatic cancers) and in uterine leiomyosarcoma (objective response in 3 of 3 patients and with ongoing responses greater than 24 months) compared with non-BRCA-associated cancer types. Responses in the BRCA1/2 cohort were numerically higher for patients with tumor mutational burden of 10 or more mutations per megabase (mut/Mb) vs less than 10 mut/Mb. The combination was well tolerated, with no new safety signals identified.

Conclusions and Relevance

In this phase 2b nonrandomized controlled trial, neither the BRCA1/2 nor ATM cohort met the prespecified OR rate of 40%. Antitumor activity for the combination of avelumab and talazoparib in patients with BRCA1/2 alterations was observed in some patients with BRCA1/2-associated tumor types and uterine leiomyosarcoma; benefit was minimal in non-BRCA-associated cancer types.

Trial Registration

ClinicalTrials.gov Identifier: NCT03565991.

Fanconi anemia caused by biallelic inactivation of BRCA2 can present with an atypical cancer phenotype in adulthood

Inherited biallelic pathogenic variants (PVs) in BRCA2 cause Fanconi Anemia complementation group D1 (FA-D1), a severe pediatric bone marrow failure and high-risk cancer syndrome. We identified biallelic BRCA2 PVs in a young adult with multiple basal cell carcinomas, adult-onset colorectal cancer and small cell neuroendocrine carcinoma, without bone marrow failure. No PVs were identified in any other known cancer susceptibility gene, and there was no evidence of reversion mosaicism. The proband's deceased sister had a classic FA-D1 presentation and was shown to carry the same biallelic BRCA2 PVs. A lymphoblastoid cell line derived from the proband demonstrated hypersensitivity to DNA damaging agents, and bone marrow showed aberrant RAD51 staining. Family expansion demonstrated the presence of BRCA2 related cancers in heterozygous family members. Our data highlight the striking phenotypic differences which can be observed within FA-D1 families and expands the clinical spectrum of FA-D1 to include adult presentation with a constellation of solid tumors not previously thought of as characteristic of Fanconi Anemia. Early recognition of this syndrome in a family could prevent further morbidity and mortality by implementation of hereditary breast and ovarian cancer screening and treatment strategies for heterozygous family members.

Abstract A003: Risks of ductal carcinoma in situ of the breast associated with pathogenic variants in cancer predisposition genes

Introduction: The relationship between germline pathogenic variants (PVs) in cancer predisposition genes and ductal carcinoma in situ (DCIS) is not well established. The objective of this study is to determine the risks of DCIS and contralateral breast cancer among women with DCIS associated with germline PVs in cancer predisposition genes. Methods: Associations between pathogenic variants in 11 cancer predisposition genes (ATM, BARD1, BRCA1, BRCA2, BRIP1, CDH1, CHEK2, MSH6, PALB2, RAD51C, and RAD51D) and DCIS were determined in case control analyses of a population-based cohort of 3876 women with DCIS and age-matched unaffected women, and in a clinical cohort of 9887 DCIS cases undergoing clinical genetic testing at Ambry Genetics and unaffected reference controls. The incidence of contralateral breast cancer risk in BRCA1, BRCA2, and PALB2 PV carriers with DCIS was also evaluated in a time-to-event analysis. Results: The mean age at diagnosis of DCIS was 50 years in the clinical testing cohort and 59 years in the population-based cohort. The frequency of PVs in 11 predisposition genes among DCIS cases was 6.9% in the clinical testing cohort and 4.9% in the population-based cohort. PVs in ATM, BRCA1, BRCA2, CHEK2, MSH6, PALB2, and RAD51D were associated with significantly increased risks (Odds Ratio (OR) &gt;2) of DCIS in the clinical testing cohort whereas only PVs in BRCA1, CHEK2, PALB2, and ATM were associated with significantly increased risks of DCIS in the population-based cohort. The cumulative incidence of contralateral breast cancer among BRCA1, BRCA2, and PALB2 PV carriers with DCIS was 11% in 5-years and 20% in 15-years. Conclusions: This study provides new insights into PVs that predispose to DCIS. In addition, it establishes an increased risk of contralateral breast cancer risk among women with DCIS who are carriers of PVs in BRCA1, BRCA2, or PALB2. These findings will guide surveillance and risk reducing strategies in germline PV carriers with DCIS.

Citation Format: Huaizhi Huang, Ronan E. Couch, Holly LaDuca, Siddhartha Yadav, Eric C. Polley, Nicholas J. Boddicker, Jie Na, Rohan D. Gnanaolivu, David E. Goldgar, Tina Pesaran, Steven N. Hart, Jill S. Dolinsky, Julie R. Palmer, Lauren Teras, Alpa V. Patel, Kathryn J. Ruddy, Janet E. Olson, Celine M. Vachon, Peter Kraft, Song Yao, Amy Trentham-Dietz, Katherine L. Nathanson, Jeffrey N. Weitzel, Susan M. Domchek, Fergus J. Couch, Chunling Hu. Risks of ductal carcinoma in situ of the breast associated with pathogenic variants in cancer predisposition genes [abstract]. In: Proceedings of the AACR Special Conference on Rethinking DCIS: An Opportunity for Prevention?; 2022 Sep 8-11; Philadelphia, PA. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_1): Abstract nr A003.

Ruxolitinib and exemestane for estrogen receptor positive, aromatase inhibitor resistant advanced breast cancer

Circulating IL-6, an activator of JAK/STAT signaling, is associated with poor prognosis and aromatase inhibitor (AI) resistance in hormone-receptor positive (HR+) breast cancer. Here we report the results of a phase 2 single-arm Simon 2-stage trial combining Ruxolitinib, an oral selective inhibitor of JAK1/2, with exemestane, a steroidal AI, in patients with HR+ metastatic breast cancer (MBC) after progression on non-steroidal AI (NSAI). Safety and efficacy were primary objectives, and analysis of inflammatory markers as predictors of response was a key secondary objective. Twenty-five subjects enrolled. The combination of ruxolitinib and exemestane was safe, though anemia requiring transfusion in 5/15 (33%) at the 25 mg dose in stage 1 led to a reduction to 15 mg twice daily in stage 2 (with no additional transfusions). Clinical benefit rate (CBR) in the overall study population was 24% (95% CI 9.4-45.1); 6/25 patients demonstrated stable disease for ≥6 months. Median progression-free survival was 2.8 months (95% CI 2.6-3.9). Exploratory biomarkers revealed high levels of systemic inflammation and 60% harbored a high-risk IL-6 genotype. Pharmacodynamics demonstrated modest on-target inhibition of phosphorylated-STAT3 by ruxolitinib at a tolerable dose. Thus, ruxolitinib combined with exemestane at a tolerable dose was safe but minimally active in AI-resistant tumors of patients with high levels of systemic inflammation. These findings highlight the need for more potent and specific therapies targeting inflammation in MBC.

Impact of integrating genomic data into the electronic health record on genetics care delivery

PURPOSE

Integrating genomic data into the electronic health record (EHR) is key for optimally delivering genomic medicine.

METHODS

The PennChart Genomics Initiative (PGI) at the University of Pennsylvania is a multidisciplinary collaborative that has successfully linked orders and results from genetic testing laboratories with discrete genetic data in the EHR. We quantified the use of the genomic data within the EHR, performed a time study with genetic counselors, and conducted key informant interviews with PGI members to evaluate the effect of the PGI's efforts on genetics care delivery.

RESULTS

The PGI has interfaced with 4 genetic testing laboratories, resulting in the creation of 420 unique computerized genetic testing orders that have been used 4073 times to date. In a time study of 96 genetic testing activities, EHR use was associated with significant reductions in time spent ordering (2 vs 8 minutes, P < .001) and managing (1 vs 5 minutes, P < .001) genetic results compared with the use of online laboratory-specific portals. In key informant interviews, multidisciplinary collaboration and institutional buy-in were identified as key ingredients for the PGI's success.

CONCLUSION

The PGI's efforts to integrate genomic medicine into the EHR have substantially streamlined the delivery of genomic medicine.

Development and Validation of a Breast Cancer Polygenic Risk Score on the Basis of Genetic Ancestry Composition

PURPOSE

Polygenic risk scores (PRSs) for breast cancer (BC) risk stratification have been developed primarily in women of European ancestry. Their application to women of non-European ancestry has lagged because of the lack of a formal approach to incorporate genetic ancestry and ancestry-dependent variant frequencies and effect sizes. Here, we propose a multiple-ancestry PRS (MA-PRS) that addresses these issues and may be useful in the development of equitable PRSs across other cancers and common diseases.

MATERIALS AND METHODS

Women referred for hereditary cancer testing were divided into consecutive cohorts for development (n = 189,230) and for independent validation (n = 89,126). Individual genetic composition as fractions of three reference ancestries (African, East Asian, and European) was determined from ancestry-informative single-nucleotide polymorphisms. The MA-PRS is a combination of three ancestry-specific PRSs on the basis of genetic ancestral composition. Stratification of risk was evaluated by multivariable logistic regression models controlling for family cancer history. Goodness-of-fit analysis compared expected with observed relative risks by quantiles of the MA-PRS distribution.

RESULTS

In independent validation, the MA-PRS was significantly associated with BC risk in the full cohort (odds ratio, 1.43; 95% CI, 1.40 to 1.46; P = 8.6 × 10-308) and within each major ancestry. The top decile of the MA-PRS consistently identified patients with two-fold increased risk of developing BC. Goodness-of-fit tests showed that the MA-PRS was well calibrated and predicted BC risk accurately in the tails of the distribution for both European and non-European women.

CONCLUSION

The MA-PRS uses genetic ancestral composition to expand the utility of polygenic risk prediction to non-European women. Inclusion of genetic ancestry in polygenic risk prediction presents an opportunity for more personalized treatment decisions for women of varying and mixed ancestries.

Copy number variants as modifiers of breast cancer risk for BRCA1/BRCA2 pathogenic variant carriers

The contribution of germline copy number variants (CNVs) to risk of developing cancer in individuals with pathogenic BRCA1 or BRCA2 variants remains relatively unknown. We conducted the largest genome-wide analysis of CNVs in 15,342 BRCA1 and 10,740 BRCA2 pathogenic variant carriers. We used these results to prioritise a candidate breast cancer risk-modifier gene for laboratory analysis and biological validation. Notably, the HR for deletions in BRCA1 suggested an elevated breast cancer risk estimate (hazard ratio (HR) = 1.21), 95% confidence interval (95% CI = 1.09-1.35) compared with non-CNV pathogenic variants. In contrast, deletions overlapping SULT1A1 suggested a decreased breast cancer risk (HR = 0.73, 95% CI 0.59-0.91) in BRCA1 pathogenic variant carriers. Functional analyses of SULT1A1 showed that reduced mRNA expression in pathogenic BRCA1 variant cells was associated with reduced cellular proliferation and reduced DNA damage after treatment with DNA damaging agents. These data provide evidence that deleterious variants in BRCA1 plus SULT1A1 deletions contribute to variable breast cancer risk in BRCA1 carriers.

Polygenic risk scores for prediction of breast cancer risk in women of African ancestry: a cross-ancestry approach

Polygenic risk scores (PRSs) are useful for predicting breast cancer risk, but the prediction accuracy of existing PRSs in women of African ancestry (AA) remains relatively low. We aim to develop optimal PRSs for the prediction of overall and estrogen receptor (ER) subtype-specific breast cancer risk in AA women. The AA dataset comprised 9235 cases and 10 184 controls from four genome-wide association study (GWAS) consortia and a GWAS study in Ghana. We randomly divided samples into training and validation sets. We built PRSs using individual-level AA data by a forward stepwise logistic regression and then developed joint PRSs that combined (1) the PRSs built in the AA training dataset and (2) a 313-variant PRS previously developed in women of European ancestry. PRSs were evaluated in the AA validation set. For overall breast cancer, the odds ratio per standard deviation of the joint PRS in the validation set was 1.34 [95% confidence interval (CI): 1.27-1.42] with the area under receiver operating characteristic curve (AUC) of 0.581. Compared with women with average risk (40th-60th PRS percentile), women in the top decile of the PRS had a 1.98-fold increased risk (95% CI: 1.63-2.39). For PRSs of ER-positive and ER-negative breast cancer, the AUCs were 0.608 and 0.576, respectively. Compared with existing methods, the proposed joint PRSs can improve prediction of breast cancer risk in AA women.

Classification of BRCA2 Variants of Uncertain Significance (VUS) Using an ACMG/AMP Model Incorporating a Homology-Directed Repair (HDR) Functional Assay

PURPOSE

The identification of variants of uncertain significance (VUS) in the BRCA1 and BRCA2 genes by hereditary cancer testing poses great challenges for the clinical management of variant carriers. The ACMG/AMP (American College of Medical Genetics and Genomics/Association for Molecular Pathology) variant classification framework, which incorporates multiple sources of evidence, has the potential to establish the clinical relevance of many VUS. We sought to classify the clinical relevance of 133 single-nucleotide substitution variants encoding missense variants in the DNA-binding domain (DBD) of BRCA2 by incorporating results from a validated functional assay into an ACMG/AMP-variant classification model from a hereditary cancer-testing laboratory.

EXPERIMENTAL DESIGN

The 133 selected VUS were evaluated using a validated homology-directed double-strand DNA break repair (HDR) functional assay. Results were combined with clinical and genetic data from variant carriers in a rules-based variant classification model for BRCA2.

RESULTS

Of 133 missense variants, 44 were designated as non-functional and 89 were designated as functional in the HDR assay. When combined with genetic and clinical information from a single diagnostic laboratory in an ACMG/AMP-variant classification framework, 66 variants previously classified by the diagnostic laboratory were correctly classified, and 62 of 67 VUS (92.5%) were reclassified as likely pathogenic (n = 22) or likely benign (n = 40). In total, 44 variants were classified as pathogenic/likely pathogenic, 84 as benign/likely benign, and 5 remained as VUS.

CONCLUSIONS

Incorporation of HDR functional analysis into an ACMG/AMP framework model substantially improves BRCA2 VUS re-classification and provides an important tool for determining the clinical relevance of individual BRCA2 VUS.

Niraparib plus nivolumab or niraparib plus ipilimumab in patients with platinum-sensitive advanced pancreatic cancer: a randomised, phase 1b/2 trial

BACKGROUND

Establishing alternatives to lifelong chemotherapy for patients with advanced pancreatic cancer has been proposed to address chemotherapy resistance and cumulative toxicity. Poly(ADP-ribose) polymerase (PARP) inhibitors have shown efficacy in this setting, and concurrent immune checkpoint blockade could offer synergistic tumour control. The aim of this study was to test the safety and antitumour activity of maintenance with PARP inhibition combined with immune checkpoint blockade in patients with advanced pancreatic cancer who had a stable response to platinum-based chemotherapy.

METHODS

We conducted an open-label, randomised, phase 1b/2 study of niraparib plus anti-PD-1 (nivolumab) or anti-CTLA-4 (ipilimumab) therapy for patients with advanced pancreatic cancer whose cancer had not progressed after at least 16 weeks of platinum-based therapy. Patients were randomly assigned (1:1) via permuted block randomisation (block sizes 2 and 4) to niraparib 200 mg orally per day plus either nivolumab 240 mg intravenously every 2 weeks (later changed to 480 mg intravenously every 4 weeks based on manufacturer update) or ipilimumab 3 mg/kg intravenously every 4 weeks for four doses. The primary endpoints were safety and progression-free survival at 6 months. Treatment groups were not compared for activity, which was assessed in each group against a clinically meaningful progression-free survival at 6 months of 44% (null hypothesis). Superiority of a treatment regimen could be declared if 6-month progression-free survival was 60%, and inferiority if 6-month progression-free survival was 27%. All patients who received at least one dose of study treatment and had at least one post-treatment assessment of response according to Response Evaluation Criteria in Solid Tumours version 1.1 were included in the efficacy population. The safety population consisted of all patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT03404960, and enrolment is completed and follow-up is ongoing.

FINDINGS

91 patients were enrolled between Feb 7, 2018, and Oct 5, 2021 and were randomly assigned to niraparib plus nivolumab (n=46) or niraparib plus ipilimumab (n=45). Of these patients, 84 were evaluable for the progression-free survival endpoint (niraparib plus nivolumab=44; niraparib plus ipilimumab=40). Median follow-up was 23·0 months (IQR 15·0-31·5). 6-month progression-free survival was 20·6% (95% CI 8·3-32·9; p=0·0002 vs the null hypothesis of 44%) in the niraparib plus nivolumab group; and 59·6% (44·3-74·9; p=0·045) in the niraparib plus ipilimumab group. Ten (22%) of 46 patients in the niraparib plus nivolumab group and 23 (50%) of 45 patients in the niraparib plus ipilimumab group had a grade 3 or worse treatment-related adverse event. The most common grade 3 or worse adverse events in the niraparib plus nivolumab group were hypertension (in four [8%] patients), anaemia (two [4%]), and thrombocytopenia (two [4%]) whereas in the niraparib plus ipilimumab group these were fatigue (in six [14%]), anaemia (five [11%]), and hypertension (four [9%]). There were no treatment-related deaths.

INTERPRETATION

The primary endpoint of 6-month progression-free survival was met in the niraparib plus ipilimumab maintenance group, whereas niraparib plus nivolumab yielded inferior progression-free survival. These findings highlight the potential for non-cytotoxic maintenance therapies in patients with advanced pancreatic cancer.

FUNDING

Bristol Myers Squibb, GlaxoSmithKline, the Basser Center Young Leadership Council, The Konner Foundation, The Pearl and Philip Basser Innovation Research Award, the Anonymous Foundation, and the US National Institutes of Health.

Abstract PL01-05: Genomic medicine meets cancer interception

The increased identification of individuals with an elevated risk of developing cancer based on inherited genetic susceptibility allows for targeted cancer interception opportunities. Understanding the molecular basis for cancer susceptibility creates the potential to disrupt the oncogenic process even after it has started. Individuals with pathogenic variants in BRCA1 and BRCA2 are at increased risk for the development of breast, ovarian, pancreatic, and prostate cancers. Work over the past decade has allowed for an understanding of the cells of origin of BRCA1 - related breast cancer and has led to a Phase III study of denosumab vs placebo to examine the impact of denosumab on breast cancer risk. The adjuvant study of the PARP inhibitor olaparib in high risk BRCA-associated breast cancer demonstrated an improvement in event free survival along with a favorable safety profile, paving the way for further work in the prevention space. Immunologic approaches have led to clinical trials using vaccines which will include healthy BRCA1/2 carriers. As our molecular understanding of BRCA haploinsufficiency improves, so too will our options for cancer interception. All of this work could lead to a halo effect with impact on sporadic cancer interception.

Citation Format: Susan M. Domchek. Genomic medicine meets cancer interception [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr PL01-05.

Cancer vaccines

Given the renewed interest in vaccine development sparked by the COVID-19 pandemic, we are revisiting the current state of vaccine development for cancer prevention and treatment. Experts discuss different vaccine types, their antigens and modes of action, and where we stand on their clinical development, plus the challenges we need to overcome for their broad implementation.