The current state of molecular testing in the treatment of patients with solid tumors, 2019.

The world of molecular profiling has undergone revolutionary changes over the last few years as knowledge, technology, and even standard clinical practice have evolved. Broad molecular profiling is now nearly essential for all patients with metastatic solid tumors. New agents have been approved based on molecular testing instead of tumor site of origin. Molecular profiling methodologies have likewise changed such that tests that were performed on patients a few years ago are no longer complete and possibly inaccurate today. As with all rapid change, medical providers can quickly fall behind or struggle to find up-to-date sources to ensure he or she provides optimum care. In this review, the authors provide the current state of the art for molecular profiling/precision medicine, practice standards, and a view into the future ahead.

Investigating potential immune mechanisms of trilaciclib administered prior to chemotherapy in patients with metastatic triple-negative breast cancer.

PURPOSE: In a phase II trial in patients with metastatic triple-negative breast cancer (mTNBC; NCT02978716), administering trilaciclib prior to gemcitabine plus carboplatin (GCb) enhanced T-cell activation and improved overall survival versus GCb alone. The survival benefit was more pronounced in patients with higher immune-related gene expression. We assessed immune cell subsets and used molecular profiling to further elucidate effects on antitumor immunity. METHODS: Patients with mTNBC and ≤ 2 prior chemotherapy regimens for locally recurrent TNBC or mTNBC were randomized 1:1:1 to GCb on days 1 and 8, trilaciclib prior to GCb on days 1 and 8, or trilaciclib alone on days 1 and 8, and prior to GCb on days 2 and 9. Gene expression, immune cell populations, and Tumor Inflammation Signature (TIS) scores were assessed in baseline tumor samples, with flow cytometric analysis and intracellular and surface cytokine staining used to assess immune cell populations and function. RESULTS: After two cycles, the trilaciclib plus GCb group (n = 68) had fewer total T cells and significantly fewer CD8+ T cells and myeloid-derived suppressor cells compared with baseline, with enhanced T-cell effector function versus GCb alone. No significant differences were observed in patients who received GCb alone (n = 34). Of 58 patients in the trilaciclib plus GCb group with antitumor response data, 27 had an objective response. RNA sequencing revealed a trend toward higher baseline TIS scores among responders versus non­responders. CONCLUSION: The results suggest that administering trilaciclib prior to GCb may modulate the composition and response of immune cell subsets to TNBC.

Checkpoint inhibitor therapy for metastatic triple-negative breast cancer.

Immunotherapy has become a mainstay of cancer treatment in many malignancies, though its application in breast cancer remains limited. Of the breast cancer subtypes, triple-negative breast cancers (TNBCs) are characterized by immune activation and infiltration and more commonly express biomarkers associated with response to immunotherapy. Checkpoint inhibitor therapy has shown promising activity in metastatic TNBC. In 2019, the US FDA granted accelerated approval of atezolizumab, a programmed death-ligand 1 (PD-L1) inhibitor, in combination with nab-paclitaxel for unresectable locally advanced or metastatic PD-L1-positive TNBC, based on the results of the phase III IMpassion130 trial. In 2020, the FDA also granted accelerated approval of pembrolizumab, a PD-1 inhibitor, in combination with chemotherapy for locally recurrent unresectable and metastatic PD-L1-positive TNBC, based on results of the phase III KEYNOTE-355 trial. Additional combination strategies are being explored in the treatment of metastatic TNBC, with the goal of augmenting antitumor activity. In this review, the clinical development of checkpoint inhibitors in the treatment of metastatic TNBC will be discussed, including clinical outcomes with monotherapy and combination therapy regimens, biomarkers that may predict for benefit, and future directions in the field.

Molecular characterization of ESR1 variants in breast cancer.

PURPOSE: Estrogen receptor 1 (ESR1) mutations and fusions typically arise in patients with hormone receptor-positive breast cancer after aromatase inhibitor therapy, whereby ESR1 is constitutively activated in a ligand-independent manner. These variants can impact treatment response. Herein, we characterize ESR1 variants among molecularly profiled advanced breast cancers. METHODS: DNA next-generation sequencing (592-gene panel) data from 9860 breast cancer samples were retrospectively reviewed. Gene fusions were detected using the ArcherDx fusion assay or whole transcriptome sequencing (n = 344 and n = 4305, respectively). Statistical analyses included Chi-square and Fisher's exact tests. RESULTS: An ESR1 ligand-binding domain (LBD) mutation was detected in 8.6% of tumors evaluated and a pathogenic ESR1 fusion was detected in 1.6%. Most ESR1 LBD mutations/fusions were from estrogen receptor (ER)-positive samples (20.1% and 4.9%, respectively). The most common ESR1 LBD mutations included D538G (3.3%), Y537S (2.3%), and E380Q (1.1%) mutations. Among biopsy sites, ESR1 LBD mutations were most observed in liver metastases. Pathogenic ESR1 fusions were identified in 76 samples (1.6%) with 40 unique fusion partners. Evaluating co-alterations, ESR1 variant (mutation/fusion) samples more frequently expressed androgen receptor (78.0% vs 58.6, P < 0.0001) and less frequently immune checkpoint proteins than ESR1 wild-type (PD-1 20.0% vs 53.4, P < 0.05; immune cell PD-L1 10.0% vs 30.2, P < 0.0001). CONCLUSION: We have described one of the largest series of ESR1 fusions reported. ESR1 LBD mutations were commonly identified in ER-positive disease. Limited data exists regarding the clinical impact of ESR1 fusions, which could be an area for future therapeutic exploration.

Does Residual Cancer Burden Predict Local Recurrence After Neoadjuvant Chemotherapy?

BACKGROUND: The extent of residual disease after neoadjuvant chemotherapy (NAC) can be quantified by the Residual Cancer Burden (RCB), a prognostic tool used to estimate survival outcomes in breast cancer. This study investigated the association between RCB and locoregional recurrence (LRR). METHODS: The study reviewed 532 women with breast cancer who underwent NAC between 2010 and 2016. Relapse in the ipsilateral breast, skin/subcutis at the surgical site, chest wall, pectoralis, or regional lymph nodes defined an LRR. The LRR cumulative incidence (LRCI) was estimated using the Fine and Gray competing-risks model, with death and distant recurrence defined as competing events. The association of LRCI with prognostic variables was evaluated. RESULTS: Overall, 5.5% of the patients experienced an LRR after a median follow-up period of 65 months. The 5-year LRCI rates by RCB were as follows: RCB-0 (0.9%), RCB-1 (3.2%), RCB-2 (6.0%), and RCB-3 (12.9%). In the univariable analysis, LRCI varied significantly by RCB (p = 0.010). The multivariable analysis showed a significant association of LRCI with increasing RCB, and the patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) phenotype were at lower risk for LRR than those with HER2+ and triple-negative cancers (p < 0.032). The patients with RCB-3 were at a higher risk for local relapse than those with RCB-0 (hazard ratio, 13.78; confidence interval, 2.25-84.45; p = 0.04). Type of operation (p = 0.04) and use of adjuvant radiation (p = 0.046) were statistically significant in the multivariable model. CONCLUSIONS: The study results demonstrate a significant association between LRCI and increasing RCB, although distant recurrence is a substantial driver of disease outcomes. Future prospective studies should examine the role of RCB in clinical decisions regarding indications for adjuvant therapy.

Trilaciclib prior to gemcitabine plus carboplatin for metastatic triple-negative breast cancer: phase III PRESERVE 2.

Triple-negative breast cancer (TNBC) is an aggressive malignancy for which cytotoxic chemotherapy remains the backbone of treatment. Trilaciclib is an intravenous cyclin-dependent kinase 4/6 inhibitor that induces transient cell cycle arrest of hematopoietic stem and progenitor cells and immune cells during chemotherapy exposure, protecting them from chemotherapy-induced damage and enhancing immune activity. Administration of trilaciclib prior to gemcitabine plus carboplatin (GCb) significantly improved overall survival (OS) compared with GCb alone in an open-label phase II trial in patients with metastatic TNBC, potentially through protection and direct activation of immune function. The randomized, double-blind, placebo-controlled, phase III PRESERVE 2 trial will evaluate the efficacy and safety of trilaciclib administered prior to GCb in patients with locally advanced unresectable or metastatic TNBC. Clinical Trial Registration: NCT04799249 (ClinicalTrials.gov).

Fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection plus chemotherapy in HER2-positive early breast cancer (FeDeriCa): a randomised, open-label, multicentre, non-inferiority, phase 3 study.

BACKGROUND: A subcutaneous formulation of pertuzumab and trastuzumab with recombinant human hyaluronidase in one ready-to-use, fixed-dose combination vial (pertuzumab, trastuzumab, and hyaluronidase-zzxf) was approved by the US Food and Drug Administration (FDA) on June 29, 2020. We report the primary analysis of the FeDeriCa study, which was designed to assess the pharmacokinetics, efficacy, and safety of the fixed-dose subcutaneous formulation compared to intravenous pertuzumab plus trastuzumab in patients with HER2-positive early breast cancer in the neoadjuvant-adjuvant setting. METHODS: FeDeriCa, a randomised, open-label, international, multicentre, non-inferiority, phase 3 study, was done across 106 sites in 19 countries. Patients aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0 or 1, HER2-positive, operable, locally advanced, or inflammatory stage II-IIIC breast cancer, and a left ventricular ejection fraction of 55% or more were randomly assigned (1:1), using a voice-based or web-based response system, to receive intravenous pertuzumab (840 mg loading dose, followed by 420 mg maintenance doses) plus intravenous trastuzumab (8 mg/kg loading dose, followed by 6 mg/kg maintenance doses) or the fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection (1200 mg pertuzumab plus 600 mg trastuzumab loading dose in 15 mL, followed by 600 mg pertuzumab plus 600 mg trastuzumab maintenance doses in 10 mL), both administered every 3 weeks with neoadjuvant chemotherapy. Patients were stratified by hormone receptor status, clinical stage, and chemotherapy regimen. The investigator selected one of the two protocol-approved standard chemotherapy regimens before randomisation. Four cycles of HER2-targeted therapy were administered concurrently with the taxane. After surgery, patients continued the HER2-targeted therapy to receive an additional 14 cycles (total of 18). The primary endpoint was non-inferiority of the cycle 7 pertuzumab serum trough concentration (Ctrough; ie, cycle 8 predose pertuzumab concentration) within the fixed-dose combination for subcutaneous injection versus intravenous pertuzumab plus trastuzumab in the per-protocol pharmacokinetic population (all enrolled patients who adhered to prespecified criteria for pharmacokinetic assessment). Non-inferiority was concluded if the lower bound of the 90% CI of the geometric mean ratio was 0·8 or higher. The safety population included all patients who received at least one dose of study medication, including chemotherapy or HER2-targeted therapy. Enrolment, neoadjuvant therapy, and surgery have been completed; adjuvant treatment and follow-up are ongoing. The trial is registered with ClinicalTrials.gov, NCT03493854. FINDINGS: Between June 14, 2018, and Dec 24, 2018, 252 patients were randomly assigned to the intravenous infusion group and 248 to the fixed-dose combination group. The geometric mean ratio of pertuzumab serum Ctrough subcutaneous to serum Ctrough intravenous was 1·22 (90% CI 1·14-1·31). The most common grade 3-4 adverse events occurring during neoadjuvant treatment with HER2-targeted therapy plus chemotherapy in 5% or more of patients were neutropenia (34 [13%] of 252 patients in the intravenous infusion group vs 35 [14%] of 248 patients in the fixed-dose combination group), decreased neutrophil count (31 [12%] vs 27 [11%]), febrile neutropenia (14 [6%] vs 16 [6%]), diarrhoea (12 [5%] vs 17 [7%]), and decreased white blood cell count (18 [7%] vs nine [4%]). At least one treatment-related serious adverse event was reported in 25 (10%) patients in the intravenous infusion group and 26 (10%) patients in the fixed-dose combination group. One patient in each treatment group had an adverse event that led to death (urosepsis in the intravenous infusion group and acute myocardial infarction in the fixed-dose combination group); neither death was related to HER2-targeted therapy. INTERPRETATION: The study met its primary endpoint: the fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection provides non-inferior cycle 7 pertuzumab serum Ctrough concentrations to intravenous pertuzumab plus trastuzumab in the neoadjuvant setting with comparable total pathological complete response rates, supporting the FDA approval. Safety was similar between treatment groups, and in line with other pertuzumab, trastuzumab, and chemotherapy trials. Follow-up is ongoing for long-term outcomes, including efficacy and long-term safety. FUNDING: F Hoffmann-La Roche and Genentech.

Final results of the double-blind placebo-controlled randomized phase 2 LOTUS trial of first-line ipatasertib plus paclitaxel for inoperable locally advanced/metastatic triple-negative breast cancer.

PURPOSE: In LOTUS (NCT02162719), adding the oral AKT inhibitor ipatasertib to first-line paclitaxel for locally advanced/metastatic triple-negative breast cancer (aTNBC) improved progression-free survival (PFS; primary endpoint), with an enhanced effect in patients with PIK3CA/AKT1/PTEN-altered tumors (FoundationOne next-generation sequencing [NGS] assay). We report final overall survival (OS) results. METHODS: Eligible patients had measurable previously untreated aTNBC. Patients were stratified by prior (neo)adjuvant therapy, chemotherapy-free interval, and tumor immunohistochemistry PTEN status, and were randomized 1:1 to paclitaxel 80 mg/m2 (days 1, 8, 15) plus ipatasertib 400 mg or placebo (days 1-21) every 28 days until disease progression or unacceptable toxicity. OS (intent-to-treat [ITT], immunohistochemistry PTEN-low, and PI3K/AKT pathway-activated [NGS PIK3CA/AKT1/PTEN-altered] populations) was a secondary endpoint. RESULTS: Median follow-up was 19.0 versus 16.0 months in the ipatasertib-paclitaxel versus placebo-paclitaxel arms, respectively. In the ITT population (n = 124), median OS was numerically longer with ipatasertib-paclitaxel than placebo-paclitaxel (hazard ratio 0.80, 95% CI 0.50-1.28; median 25.8 vs 16.9 months, respectively; 1-year OS 83% vs 68%). Likewise, median OS favored ipatasertib-paclitaxel in the PTEN-low (n = 48; 23.1 vs 15.8 months; hazard ratio 0.83) and PIK3CA/AKT1/PTEN-altered (n = 42; 25.8 vs 22.1 months; hazard ratio 1.13) subgroups. The ipatasertib-paclitaxel safety profile was unchanged. CONCLUSIONS: Final OS results show a numerical trend favoring ipatasertib-paclitaxel and median OS exceeding 2 years with ipatasertib-paclitaxel. Overall, results are consistent with the reported PFS benefit; interpretation within biomarker-defined subgroups is complicated by small sample sizes and TNBC heterogeneity.

The evolving role of immune checkpoint inhibitors in the treatment of triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer for which chemotherapy had been the only active treatment option once metastatic disease developed. Immune checkpoint inhibitors (ICIs) are now available to treat patients with advanced TNBC who have programmed cell death ligand 1 (PD-L1)-positive tumors; these agents have been shown to improve clinical outcomes. Additionally, long-term disease control can be achieved in a subset of patients. Continued investigations of ICIs and optimal combinations with chemotherapy and targeted agents to enhance the immune response are ongoing, along with studies aimed at identifying the patients most likely to benefit. For early-stage TNBC, the data to date on administering ICI-based combination therapies in the neoadjuvant setting are compelling and suggest that the benefit from immunotherapy does not depend on PD-L1 expression. This review will discuss the clinical trial data on ICIs as monotherapy and in combination with chemotherapy in the treatment of patients with metastatic and early-stage TNBC.

Actionable co-alterations in breast tumors with pathogenic mutations in the homologous recombination DNA damage repair pathway.

PURPOSE: Homologous recombination (HR)-deficient breast tumors may have genomic alterations that predict response to treatment with PARP inhibitors and other targeted therapies. METHODS: Comprehensive molecular profiles of 4647 breast tumors performed at Caris Life Sciences using 592-gene NGS were reviewed to identify somatic pathogenic mutations in HR genes ARID1A, ATM, ATRX, BAP1, BARD1, BLM, BRCA1/2, BRIP1, CHEK1/2, FANCA/C/D2/E/F/G/L, KMT2D, MRE11, NBN, PALB2, RAD50/51/51B, and WRN, as well as 41 markers that may be associated with treatment response to targeted anticancer therapies. RESULTS: 17.9% of breast tumors had HR mutations (HR-MT, 831/4647) [ER/PR+ , HER2- 18.3%, n = 2183; TNBC 18.2%, n = 1568; ER/PR+ , HER2+ 15.6%, n = 237; ER/PR-, HER2+ 12.9%, n = 217; unknown n = 442]. Mean TMB was higher for HR-MT tumors across subtypes (9.2 mut/Mb vs 7.6 h-wild type (HR-WT), p ≤ 0.0001) and independent of microsatellite status. MSI-H/dMMR was more frequent among HR-MT tumors (2.1% HR-MT vs 0.2% HR-WT, p ≤ 0.0001), as was tumor PD-L1 overexpression (13.2% HR-MT vs 11.0% HR-WT, p = 0.08). Additional co-alterations were similar between HR-MT and HR-WT, with the exception of PIK3CA (30.3% HR-WT vs 26.4% HR-MT, p = 0.024) and AKT1 (3.7% HR-WT vs 2.1% HR-MT, p = 0.021). AR overexpression and PIK3CA mutations were more common among ER/PR+ tumors. ERBB2 mutations were seen in both HER2+ and HER2- tumors. CONCLUSIONS: HR-MT was common across breast cancer subtypes and co-occurred more frequently with markers of response to immunotherapy (MSI-H/dMMR, TMB) compared to HR-WT tumors. Mutations were identified in both HR-MT and HR-WT tumors that suggest other targets for treatment. Clinical trials combining HRD-targeted agents and immunotherapy are underway and could be enriched through comprehensive molecular profiling.

A phase I study of AT-101, a BH3 mimetic, in combination with paclitaxel and carboplatin in solid tumors.

Background AT-101 is a BH3 mimetic that inhibits the heterodimerization of Bcl-2, Bcl-xL, Bcl-W, and Mcl-1 with pro-apoptotic proteins, thereby lowering the threshold for apoptosis. This phase I trial investigated the MTD of AT-101 in combination with paclitaxel and carboplatin in patients with advanced solid tumors. Methods Patients were treated with AT-101 (40 mg) every 12 h on days 1, 2 and 3 of each cycle combined with varying dose levels (DL) of paclitaxel and carboplatin [DL1: paclitaxel (150 mg/m2) and carboplatin (AUC 5) on day 1 of each cycle; DL2: paclitaxel (175 mg/m2) and carboplatin (AUC 6) on day 1 of each cycle]. Secondary objectives included characterizing toxicity, efficacy, pharmacokinetics, and pharmacodynamics of the combination. Results Twenty-four patients were treated across two DLs with a planned expansion cohort. The most common tumor type was prostate (N = 11). Two patients experienced DLTs: grade 3 abdominal pain at DL1 and grade 3 ALT increase at DL2; however, the MTD was not determined. Moderate hematologic toxicity was observed. One CR was seen in a patient with esophageal cancer and 4 patients achieved PRs (1 NSCLC, 3 prostate). PD studies did not yield statistically significant decreases in Bcl-2 and caspase 3 protein levels, or increased apoptotic activity induced by AT-101. Conclusion The combination of AT-101 at 40 mg every 12 h on days 1, 2 and 3 combined with paclitaxel and carboplatin was safe and tolerable. Based on the modest clinical efficacy seen in this trial, this combination will not be further investigated. Clinical Trial Registration: NCT00891072, CTEP#: 8016.

Trilaciclib plus chemotherapy versus chemotherapy alone in patients with metastatic triple-negative breast cancer: a multicentre, randomised, open-label, phase 2 trial.

BACKGROUND: Trilaciclib is an intravenous cell-cycle inhibitor that transiently maintains immune cells and haemopoietic stem and progenitor cells in G1 arrest. By protecting the immune cells and bone marrow from chemotherapy-induced damage, trilaciclib has the potential to optimise antitumour activity while minimising myelotoxicity. We report safety and activity data for trilaciclib plus gemcitabine and carboplatin chemotherapy in patients with metastatic triple-negative breast cancer. METHODS: In this randomised, open-label, multicentre, phase 2 study, adult patients (aged ≥18 years) with evaluable, biopsy-confirmed, locally recurrent or metastatic triple-negative breast cancer who had no more than two previous lines of chemotherapy were recruited from 26 sites in the USA, three in Serbia, two in North Macedonia, one in Croatia, and one in Bulgaria; sites were academic and community hospitals. Availability of diagnostic samples of tumour tissue confirming triple-negative breast cancer was a prerequisite for enrolment. Eligible patients were randomly assigned (1:1:1) by an interactive web-response system, stratified by number of previous lines of systemic therapy and the presence of liver metastases, to receive intravenous gemcitabine 1000 mg/m2 and intravenous carboplatin (area under the concentration-time curve 2 µg × h/mL) on days 1 and 8 (group 1), gemcitabine and carboplatin plus intravenous trilaciclib 240 mg/m2 on days 1 and 8 (group 2), or gemcitabine and carboplatin on days 2 and 9 plus trilaciclib on days 1, 2, 8, and 9 (group 3) of 21-day cycles. Patients continued treatment until disease progression, unacceptable toxicity, withdrawal of consent, or discontinuation by the investigator. The primary objective was to assess the safety and tolerability of combining trilaciclib with gemcitabine and carboplatin chemotherapy. The primary endpoints were duration of severe neutropenia during cycle 1 and the occurrence of severe neutropenia during the treatment period. Overall survival was included as a key secondary endpoint. Analyses were in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study treatment. This study is registered with EudraCT, 2016-004466-26, and ClinicalTrials.gov, NCT02978716, and is ongoing but closed to accrual. FINDINGS: Between Feb 7, 2017, and May 15, 2018, 142 patients were assessed for eligibility and 102 were randomly assigned to group 1 (n=34), group 2 (n=33), or group 3 (n=35). Of all patients, 38 (37%) had received one or two lines of previous chemotherapy in the metastatic setting. Median follow-up was 8·4 months (IQR 3·8-13·6) for group 1, 12·7 months (5·5-17·4) for group 2, and 12·9 months (6·7-16·8) for group 3. Data cutoff for myelosuppression endpoints was July 30, 2018, and for antitumour activity endpoints was May 17, 2019. During cycle 1, mean duration of severe neutropenia was 0·8 day (SD 2·4) in group 1, 1·5 days (3·5) in group 2, and 1·0 day (2·6) in group 3 (group 3 vs group 1 one-sided adjusted p=0·70). Severe neutropenia occurred in nine (26%) of 34 patients in group 1, 12 (36%) of 33 patients in group 2, and eight (23%) of 35 patients in group 3 (p=0·70). Overall survival was 12·6 months (IQR 5·8-15·6) in group 1, 20·1 months (9·4-not reached) in group 2, and 17·8 months (8·8-not reached) in group 3 (group 3 vs group 1 two-sided p=0·0023). The most common treatment-emergent adverse events were anaemia (22 [73%] of 34), neutropenia (21 [70%]), and thrombocytopenia (18 [60%]) in group 1; neutropenia (27 [82%] of 33), thrombocytopenia (18 [55%]) and anaemia (17 [52%]) in group 2; and neutropenia (23 [66%] of 35), thrombocytopenia (22 [63%]), and nausea (17 [49%]) in group 3. There were no treatment-related deaths. INTERPRETATION: No significant differences were observed in myelosuppression endpoints with trilaciclib plus gemcitabine and carboplatin in patients with metastatic triple-negative breast cancer; however, the regimen was generally well tolerated and overall survival results were encouraging. Further studies of trilaciclib in this setting are warranted. FUNDING: G1 Therapeutics.

Development of poly(ADP-ribose) polymerase inhibitors in the treatment of BRCA-mutated breast cancer.

The poly(ADP-ribose) polymerases (PARPs) 1 and 2 are DNA-binding enzymes that play a critical role in the repair of DNA. The use of PARP inhibitors is a rational therapeutic approach to selectively killing a subset of cancer cells with deficiencies in DNA repair pathways. PARP inhibitors that have undergone clinical investigation in the treatment of breast cancer include olaparib, talazoparib, veliparib, niraparib, and rucaparib. The antitumor activity of PARP inhibitors as single agents has been demonstrated in BRCA-associated metastatic breast cancer. In 2018, olaparib became the first oral PARP inhibitor to receive approval in the United States for the treatment of advanced BRCA-mutated breast cancer, an approval that represents a major change in the treatment paradigm for this subtype of breast cancer. PARP inhibition plus chemotherapy and PARP inhibition plus immunotherapy are novel approaches undergoing extensive study in breast cancer. This review focuses on the clinical development of PARP inhibitors administered singly or in combination with other agents for early-stage and metastatic BRCA-mutated breast cancer.

Ipatasertib plus paclitaxel versus placebo plus paclitaxel as first-line therapy for metastatic triple-negative breast cancer (LOTUS): a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial.

BACKGROUND: The oral AKT inhibitor ipatasertib is being investigated in cancers with a high prevalence of PI3K/AKT pathway activation, including triple-negative breast cancer. The LOTUS trial investigated the addition of ipatasertib to paclitaxel as first-line therapy for triple-negative breast cancer. METHODS: In this randomised, placebo-controlled, double-blind, phase 2 trial, women aged 18 years or older with measurable, inoperable, locally advanced or metastatic triple-negative breast cancer previously untreated with systemic therapy were recruited from 44 hospitals in South Korea, the USA, France, Spain, Taiwan, Singapore, Italy, and Belgium. Enrolled patients were randomly assigned (1:1) to receive intravenous paclitaxel 80 mg/m2 (days 1, 8, 15) with either ipatasertib 400 mg or placebo once per day (days 1-21) every 28 days until disease progression or unacceptable toxicity. Randomisation was by stratified permuted blocks (block size of four) using an interactive web-response system with three stratification criteria: previous (neo)adjuvant therapy, chemotherapy-free interval, and tumour PTEN status. The co-primary endpoints were progression-free survival in the intention-to-treat population and progression-free survival in the PTEN-low (by immunohistochemistry) population. This ongoing trial is registered with ClinicalTrials.gov (NCT02162719). FINDINGS: Between Sept 2, 2014, and Feb 4, 2016, 166 patients were assessed for eligibility and 124 patients were enrolled and randomly assigned to paclitaxel plus ipatasertib (n=62) or paclitaxel plus placebo (n=62). Median follow-up was 10·4 months (IQR 6·5-14·1) in the ipatasertib group and 10·2 months (6·0-13·6) in the placebo group. Median progression-free survival in the intention-to-treat population was 6·2 months (95% CI 3·8-9·0) with ipatasertib versus 4·9 months (3·6-5·4) with placebo (stratified hazard ratio [HR] 0·60, 95% CI 0·37-0·98; p=0·037) and in the 48 patients with PTEN-low tumours, median progression-free survival was 6·2 months (95% CI 3·6-9·1) with ipatasertib versus 3·7 months (1·9-7·3) with placebo (stratified HR 0·59, 95% CI 0·26-1·32, p=0·18). The most common grade 3 or worse adverse events were diarrhoea (14 [23%] of 61 ipatasertib-treated patients vs none of 62 placebo-treated patients), neutrophil count decreased (five [8%] vs four [6%]), and neutropenia (six [10%] vs one [2%]). No colitis, grade 4 diarrhoea, or treatment-related deaths were reported with ipatasertib. One treatment-related death occurred in the placebo group. Serious adverse events were reported in 17 (28%) of 61 patients in the ipatasertib group and nine (15%) of 62 patients in the placebo group. INTERPRETATION: Progression-free survival was longer in patients who received ipatasertib than in those who received placebo. To our knowledge, these are the first results supporting AKT-targeted therapy for triple-negative breast cancer. Ipatasertib warrants further investigation for the treatment of triple-negative breast cancer. FUNDING: F Hoffmann-La Roche.

A phase II study of combined ridaforolimus and dalotuzumab compared with exemestane in patients with estrogen receptor-positive breast cancer.

PURPOSE: Combining the mTOR inhibitor ridaforolimus and the anti-IGFR antibody dalotuzumab demonstrated antitumor activity, including partial responses, in estrogen receptor (ER)-positive advanced breast cancer, especially in high proliferation tumors (Ki67 > 15%). METHODS: This randomized, multicenter, international, phase II study enrolled postmenopausal women with advanced ER-positive breast cancer previously treated with a nonsteroidal aromatase inhibitor (NCT01234857). Patients were randomized to either oral ridaforolimus 30 mg daily for 5 of 7 days (once daily [qd] × 5 days/week) plus intravenous dalotuzumab 10 mg/kg/week or oral exemestane 25 mg/day, and stratified by Ki67 status. Due to a high incidence of stomatitis in the ridaforolimus-dalotuzumab group, two sequential, nonrandomized, reduced-dose cohorts were explored with ridaforolimus 20 and 10 mg qd × 5 days/week. The primary endpoint was progression-free survival (PFS). RESULTS: Median PFS was 21.4 weeks for ridaforolimus 30 mg qd × 5 days/week plus dalotuzumab 10 mg/kg (n = 29) and 24.3 weeks for exemestane (n = 33; hazard ratio = 1.00; P = 0.5). Overall survival and objective response rates were similar between treatment arms. The incidence of drug-related, nonserious, and serious adverse events was higher with ridaforolimus/dalotuzumab (any ridaforolimus dose) than with exemestane. Lowering the ridaforolimus dose reduced the incidence of grade 3 stomatitis, but overall toxicity remained higher than acceptable at all doses without improved efficacy. CONCLUSIONS: The combination of ridaforolimus plus dalotuzumab was no more effective than exemestane in patients with advanced ER-positive breast cancer, and the incidence of adverse events was higher. Therefore, the combination is not being further pursued.

A randomized phase II trial of ridaforolimus, dalotuzumab, and exemestane compared with ridaforolimus and exemestane in patients with advanced breast cancer.

PURPOSE: To evaluate whether adding humanized monoclonal insulin growth factor-1 receptor (IGF-1R) antibody (dalotuzumab) to mammalian target of rapamycin (mTOR) inhibitor (ridaforolimus) plus aromatase inhibitor (exemestane) improves outcomes in patients with estrogen receptor (ER)-positive advanced/metastatic breast cancer. METHODS: This randomized, open-label, phase II trial enrolled 80 postmenopausal women with high-proliferation (Ki67 index staining ≥15%), ER-positive breast cancer that progressed after a non-steroidal aromatase inhibitor (NCT01605396). Randomly assigned patients were given oral ridaforolimus 10 mg QD 5 ×/week, intravenous dalotuzumab 10 mg/kg/week, and oral exemestane 25 mg/day (R/D/E, n = 40), or ridaforolimus 30 mg QD 5 ×/week and exemestane 25 mg/day (R/E; n = 40). Primary end point was progression-free survival (PFS). RESULTS: Median PFS was 23.3 weeks for R/D/E versus 31.9 weeks for R/E (hazard ratio 1.18; 80% CI 0.81-1.72; P = 0.565). Grade 3-5 adverse events were reported in 67.5% of patients in the R/E arm and 59.0% in the R/D/E arm. Stomatitis (95.0 vs. 76.9%; P = 0.021) and pneumonitis (22.5 vs. 5.1%; P = 0.027) occurred more frequently in the R/E than the R/D/E arm; hyperglycemia (27.5 vs. 28.2%) occurred at a similar rate. CONCLUSIONS: R/D/E did not improve PFS compared with R/E. Because the PFS reported for R/E was similar to that reported for everolimus plus exemestane in patients with advanced breast cancer, it is possible that lower-dose ridaforolimus in the R/D/E arm (from overlapping toxicities with IGF1R inhibitor) contributed to lack of improved PFS.

Clinical Actionability of Comprehensive Genomic Profiling for Management of Rare or Refractory Cancers.

BACKGROUND: The frequency with which targeted tumor sequencing results will lead to implemented change in care is unclear. Prospective assessment of the feasibility and limitations of using genomic sequencing is critically important. METHODS: A prospective clinical study was conducted on 100 patients with diverse-histology, rare, or poor-prognosis cancers to evaluate the clinical actionability of a Clinical Laboratory Improvement Amendments (CLIA)-certified, comprehensive genomic profiling assay (FoundationOne), using formalin-fixed, paraffin-embedded tumors. The primary objectives were to assess utility, feasibility, and limitations of genomic sequencing for genomically guided therapy or other clinical purpose in the setting of a multidisciplinary molecular tumor board. RESULTS: Of the tumors from the 92 patients with sufficient tissue, 88 (96%) had at least one genomic alteration (average 3.6, range 0-10). Commonly altered pathways included p53 (46%), RAS/RAF/MAPK (rat sarcoma; rapidly accelerated fibrosarcoma; mitogen-activated protein kinase) (45%), receptor tyrosine kinases/ligand (44%), PI3K/AKT/mTOR (phosphatidylinositol-4,5-bisphosphate 3-kinase; protein kinase B; mammalian target of rapamycin) (35%), transcription factors/regulators (31%), and cell cycle regulators (30%). Many low frequency but potentially actionable alterations were identified in diverse histologies. Use of comprehensive profiling led to implementable clinical action in 35% of tumors with genomic alterations, including genomically guided therapy, diagnostic modification, and trigger for germline genetic testing. CONCLUSION: Use of targeted next-generation sequencing in the setting of an institutional molecular tumor board led to implementable clinical action in more than one third of patients with rare and poor-prognosis cancers. Major barriers to implementation of genomically guided therapy were clinical status of the patient and drug access. Early and serial sequencing in the clinical course and expanded access to genomically guided early-phase clinical trials and targeted agents may increase actionability. IMPLICATIONS FOR PRACTICE: Identification of key factors that facilitate use of genomic tumor testing results and implementation of genomically guided therapy may lead to enhanced benefit for patients with rare or difficult to treat cancers. Clinical use of a targeted next-generation sequencing assay in the setting of an institutional molecular tumor board led to implementable clinical action in over one third of patients with rare and poor prognosis cancers. The major barriers to implementation of genomically guided therapy were clinical status of the patient and drug access both on trial and off label. Approaches to increase actionability include early and serial sequencing in the clinical course and expanded access to genomically guided early phase clinical trials and targeted agents.

Cutaneous keratoacanthomas/squamous cell carcinomas associated with neutralization of transforming growth factor ß by the monoclonal antibody fresolimumab (GC1008).

Fresolimumab is an antibody capable of neutralizing all human isoforms of transforming growth factor beta (TGFß) and has demonstrated anticancer activity in investigational studies. Inhibition of TGFß by fresolimumab can potentially result in the development of cutaneous lesions. The aim of this study was to investigate the clinical, histological, and immunohistochemical characteristics of cutaneous neoplasms associated with fresolimumab. Skin biopsies (n = 24) were collected and analyzed from patients (n = 5) with treatment-emergent, cutaneous lesions arising during a phase 1 study of multiple doses of fresolimumab in patients (n = 29) with melanoma or renal cell carcinoma. Blinded, independent histological review and measurements of Ki-67, p53, and HPV integration were performed. Based on central review, four patients developed lesions with histological characteristics of keratoacanthomas, and of these patients, a single case of well-differentiated squamous cell carcinoma was also found. Expression of Ki-67, no evidence of p53 overexpression, and only focal positivity for human papillomavirus RNA by in situ hybridization in 4/18 cases were consistent with these findings. Following completion of fresolimumab, lesions spontaneously resolved. Therefore, benign, reversible keratoacanthomas were the most common cutaneous neoplasms observed, a finding of importance for adverse event monitoring, patient care, and optimization of therapies targeting TGFß.

Phase II randomized clinical trial evaluating neoadjuvant chemotherapy regimens with weekly paclitaxel or eribulin followed by doxorubicin and cyclophosphamide in women with locally advanced HER2-negative breast cancer: NSABP Foundation Study FB-9.

Locally advanced breast cancer (LABC) is a good setting in which to monitor response to neoadjuvant chemotherapy, to downsize the tumor (which facilitates breast-conserving surgery), and to test newer agents in untreated patients. Eribulin (E) has shown activity in patients who have undergone previous taxane, anthracycline, and capecitabine treatment. We aimed to evaluate the neoadjuvant use of E followed by doxorubicin and cyclophosphamide (AC) in patients with HER2-negative LABC, using as a control a randomized group of women who received weekly paclitaxel (WP). Fifty women with LABC were accrued January-August 2013. Patients were randomized (1:2) to receive either WP (N = 19) for 12 treatments or E (N = 31) every 3 weeks for 4 cycles followed by AC every 3 weeks for 4 cycles before surgery. 17/19 patients who took WP and 25/30 who took E completed all cycles. Patients were evaluated by clinical examination and breast MRI at baseline and after completion of E or WP. Surgical pCR in breast and lymph nodes was determined by a local pathologist following chemotherapy. Forty-nine patients received ≥1 dose of neoadjuvant chemotherapy and are included in this analysis. Forty-eight underwent surgery; one had disease that was inoperable (on E) and is included as no-pCR patient. 17/19 of these patients who took WP completed 12 doses; 28/30 on E completed 4 cycles. Six discontinued treatment on WP, E, or AC. Both treatments were well tolerated. pCR on WP = 5/19(26 %) and on E = 5/30(17 %). Both regimens were equally well tolerated with no unexpected toxicities. pCR did not suggest higher activity with E than with other standard regimens in these LABC patients.