Retrospective study to estimate the prevalence of HER2-low breast cancer (BC) and describe its clinicopathological characteristics

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Background: Approximately 50% of BCs traditionally categorized as HER2 negative (HER2-neg) express low levels of HER2 (IHC 1+ or IHC 2+/ISH-; Miglietta, NPJ Breast Cancer 2021). HER2-targeted therapies for HER2-low metastatic BC (mBC) are under investigation (eg, T-DXd in the phase 3 DESTINY-Breast04 study; NCT03734029), but HER2 assays currently used to select patients (pts) for approved anti-HER2 therapies are optimized for high HER2 expression and are not validated for HER2-low detection. A recent study found relatively poor agreement (<70% interrater agreement) in evaluation of IHC scores of 0 and 1+ using current HER2 assays (Fernandez, JAMA Oncol 2022). Our objectives were to assess the prevalence of HER2-low among HER2-neg based on rescored HER2 IHC slides after training on low-end expression scoring and to describe pt characteristics of HER2-low vs HER2 IHC 0 mBC. Preliminary results are reported for 233 of 1000 planned pts. Methods: This multicenter, retrospective study (NCT04807595) included pts with confirmed HER2-neg unresectable/mBC diagnosed between 2015 and 2017. Local laboratories, blinded to historical HER2 scores, rescored HER2 IHC-stained slides. HER2 was assessed using Ventana 4B5 and other assays. BCs were categorized as HER2-low or HER2 IHC 0. The prevalence of HER2-low BC among pts originally scored as HER2-neg was measured. Demographics (eg, age, country, race) and clinicopathological characteristics were examined via medical charts/electronic health records. Concordance between historical HER2 scores and rescores was assessed. Results: HER2 rescores were obtained for 233 pts (mean age, 54 y). HER2-low prevalence was 63.2% overall and numerically greater in hormone receptor (HR)–positive vs HR-negative subgroups (66.1% vs 54.8%; Table). No notable differences in prevalence were seen among different HER2 assays or in demographic/baseline disease characteristics between the HER2-low and HER2 IHC 0 groups. Concordance rate between historical and rescored slides for HER2-status classification was 82.3%. The presentation will include an expanded data set (≈400 pts) with additional results. Conclusions: Data on HER2-low prevalence in BC is limited. Preliminary data from this study of mBC samples suggest a somewhat higher prevalence estimate (≈63%) than a previous study of primary BC samples (≈50%). Concordance was 82%; ongoing analyses with updated data will clarify the concordance between rescored and historical HER2 slides. These data can support development of best practices for identifying pts with HER2-low expression who may benefit from HER2-targeted therapies. Clinical trial information: NCT04807595. [Table: see text]

Exploratory outcome analyses according to stage and/or residual disease in the ICON7 trial of carboplatin and paclitaxel with or without bevacizumab for newly diagnosed ovarian cancer

OBJECTIVE

In the randomized phase 3 ICON7 trial (ISRCTN91273375), adding bevacizumab to chemotherapy for newly diagnosed ovarian cancer significantly improved progression-free survival (PFS; primary endpoint) but not overall survival (OS; secondary endpoint) in the intent-to-treat (ITT) population. We explored treatment effect according to stage and extent of residual disease.

METHODS

Patients with stage IIB-IV or high-risk (grade 3/clear-cell) stage I-IIA ovarian cancer were randomized to receive six cycles of carboplatin and paclitaxel either alone or with bevacizumab 7.5 mg/kg every 3 weeks followed by single-agent bevacizumab for 12 further cycles (total duration 12 months). Post hoc exploratory analyses of subgroups defined by stage and extent of residual disease at diagnosis within the stage IIIB-IV population (European indication) was performed.

RESULTS

The PFS benefit from bevacizumab was seen consistently in all subgroups explored. The PFS hazard ratio was 0.77 (95% confidence interval [CI], 0.59-0.99) in 411 patients with stage IIIB-IV ovarian cancer with no visible residuum and 0.81 (95% CI, 0.69-0.95) in 749 patients with stage IIIB-IV disease and visible residuum. As in the ITT population, no OS difference was detected in any subgroup except the previously described 'high-risk' subgroup. Safety results in analyzed subgroups were consistent with the overall population.

CONCLUSIONS

Adding bevacizumab to front-line chemotherapy improves PFS irrespective of stage/residual disease. In patients with stage III with >1 cm residuum, stage IV or inoperable disease, this translates into an OS benefit. No OS benefit or detriment was seen in other subgroups explored.

Exploratory outcome analyses according to stage and/or residual disease in the ICON7 trial of carboplatin and paclitaxel with or without bevacizumab for newly diagnosed ovarian cancer

OBJECTIVE

In the randomized phase 3 ICON7 trial (ISRCTN91273375), adding bevacizumab to chemotherapy for newly diagnosed ovarian cancer significantly improved progression-free survival (PFS; primary endpoint) but not overall survival (OS; secondary endpoint) in the intent-to-treat (ITT) population. We explored treatment effect according to stage and extent of residual disease.

METHODS

Patients with stage IIB-IV or high-risk (grade 3/clear-cell) stage I-IIA ovarian cancer were randomized to receive six cycles of carboplatin and paclitaxel either alone or with bevacizumab 7.5 mg/kg every 3 weeks followed by single-agent bevacizumab for 12 further cycles (total duration 12 months). Post hoc exploratory analyses of subgroups defined by stage and extent of residual disease at diagnosis within the stage IIIB-IV population (European indication) was performed.

RESULTS

The PFS benefit from bevacizumab was seen consistently in all subgroups explored. The PFS hazard ratio was 0.77 (95% confidence interval [CI], 0.59-0.99) in 411 patients with stage IIIB-IV ovarian cancer with no visible residuum and 0.81 (95% CI, 0.69-0.95) in 749 patients with stage IIIB-IV disease and visible residuum. As in the ITT population, no OS difference was detected in any subgroup except the previously described 'high-risk' subgroup. Safety results in analyzed subgroups were consistent with the overall population.

CONCLUSIONS

Adding bevacizumab to front-line chemotherapy improves PFS irrespective of stage/residual disease. In patients with stage III with >1 cm residuum, stage IV or inoperable disease, this translates into an OS benefit. No OS benefit or detriment was seen in other subgroups explored.

Exploratory outcome analyses according to stage and/or residual disease in the ICON7 trial of carboplatin and paclitaxel with or without bevacizumab for newly diagnosed ovarian cancer

OBJECTIVE

In the randomized phase 3 ICON7 trial (ISRCTN91273375), adding bevacizumab to chemotherapy for newly diagnosed ovarian cancer significantly improved progression-free survival (PFS; primary endpoint) but not overall survival (OS; secondary endpoint) in the intent-to-treat (ITT) population. We explored treatment effect according to stage and extent of residual disease.

METHODS

Patients with stage IIB-IV or high-risk (grade 3/clear-cell) stage I-IIA ovarian cancer were randomized to receive six cycles of carboplatin and paclitaxel either alone or with bevacizumab 7.5 mg/kg every 3 weeks followed by single-agent bevacizumab for 12 further cycles (total duration 12 months). Post hoc exploratory analyses of subgroups defined by stage and extent of residual disease at diagnosis within the stage IIIB-IV population (European indication) was performed.

RESULTS

The PFS benefit from bevacizumab was seen consistently in all subgroups explored. The PFS hazard ratio was 0.77 (95% confidence interval [CI], 0.59-0.99) in 411 patients with stage IIIB-IV ovarian cancer with no visible residuum and 0.81 (95% CI, 0.69-0.95) in 749 patients with stage IIIB-IV disease and visible residuum. As in the ITT population, no OS difference was detected in any subgroup except the previously described 'high-risk' subgroup. Safety results in analyzed subgroups were consistent with the overall population.

CONCLUSIONS

Adding bevacizumab to front-line chemotherapy improves PFS irrespective of stage/residual disease. In patients with stage III with >1 cm residuum, stage IV or inoperable disease, this translates into an OS benefit. No OS benefit or detriment was seen in other subgroups explored.

Patients' preferences for subcutaneous trastuzumab versus conventional intravenous infusion for the adjuvant treatment of HER2-positive early breast cancer: final analysis of 488 patients in the international, randomized, two-cohort PrefHer study

BACKGROUND

Patients with HER2-positive early breast cancer (EBC) preferred subcutaneous (s.c.) trastuzumab, delivered via single-use injection device (SID), over the intravenous (i.v.) formulation (Cohort 1 of the PrefHer study: NCT01401166). Here, we report patient preference, healthcare professional satisfaction, and safety data pooled from Cohort 1 and also Cohort 2, where s.c. trastuzumab was delivered via hand-held syringe.

PATIENTS AND METHODS

Patients were randomized to receive four adjuvant cycles of 600 mg fixed-dose s.c. trastuzumab followed by four cycles of standard i.v. trastuzumab, or vice versa. The primary endpoint was overall preference proportions for s.c. or i.v., assessed by patient interviews in the evaluable ITT population.

RESULTS

A total of 245 patients were randomized to receive s.c. followed by i.v. and 243 received i.v. followed by s.c. (evaluable ITT populations: 235 and 232 patients, respectively). s.c. was preferred by 415/467 [88.9%; 95% confidence interval (CI) 85.7-91.6; P < 0.0001; two-sided test against null hypothesis of 65% s.c. preference]; 45/467 preferred i.v. (9.6%; 95% CI 7-13); 7/467 indicated no preference (1.5%; 95% CI 1-3). Clinician-reported adverse events occurred in 292/479 (61.0%) and 245/478 (51.3%) patients during the pooled s.c. and i.v. periods, respectively (P < 0.05; 2 × 2 χ(2)); 16 patients (3.3%) in each period experienced grade 3 events; none were grade 4/5.

CONCLUSIONS

PrefHer revealed compelling and consistent patient preferences for s.c. over i.v. trastuzumab, regardless of SID or hand-held syringe delivery. s.c. was well tolerated and safety was consistent with previous reports, including the HannaH study (NCT00950300). No new safety signals were identified compared with the known i.v. profile in EBC. PrefHer and HannaH confirm that s.c. trastuzumab is a validated and preferred option over i.v. for improving patients' care in HER2-positive breast cancer.

CLINICALTRIALSGOV REGISTRATION NUMBER

NCT01401166.

Pooled analysis of individual patient data from capecitabine monotherapy clinical trials in locally advanced or metastatic breast cancer

We assessed the efficacy and safety of capecitabine across treatment lines, and the impact of patient and disease characteristics on outcomes using data from phase II/III trials. Individual patient data were pooled from seven Roche/Genentech-led trials conducted from 1996 to 2008 where single-agent capecitabine was the test or control regimen for metastatic breast cancer (MBC). Data were analyzed from 805 patients: 268 in the first-line metastatic setting and 537 in the second-line or later setting. Baseline characteristics were balanced across treatment lines. Patients receiving second-line or later versus first-line capecitabine had lower objective response rates (ORR: 19.0 vs. 25.0 %, respectively, odds ratio 0.70; 95 % CI: 0.5-1.0) and significantly shorter progression-free survival (PFS: median 112.0 days [3.7 months] vs. 150.0 days [4.9 months]; p < 0.0001) and overall survival (OS: median 396.0 days [13.0 months] vs. 666.0 days [21.9 months]; p < 0.0001). In multivariate analysis by backward elimination, significantly improved ORR (p = 0.0036), PFS (p < 0.0001) and OS (p < 0.0001) with capecitabine were demonstrated in patients with estrogen receptor (ER) and/or progesterone receptor (PgR)-positive versus both ER and PgR-negative tumors. Hand-foot syndrome (HFS) was the most common adverse event (AE) in 63 % of patients. Overall, 7 % of patients discontinued and two patients (<1 %) died from treatment-related AEs. Significantly improved survival was observed in patients developing capecitabine-related HFS (p < 0.0001 PFS/OS) or diarrhea (p = 0.004 OS; p = 0.0045 PFS) versus patients without these events. In this pooled analysis of individual patient data, first-line capecitabine was associated with improved ORR, PFS, and OS versus second or later lines. Multivariate analyses identified greater ORR, PFS, and OS with capecitabine in patients with ER and/or PgR-positive versus ER/PgR-negative tumors. Safety was in-line with previous phase III trials in MBC.

Phase II study of bevacizumab in combination with trastuzumab and capecitabine as first-line treatment for HER-2-positive locally recurrent or metastatic breast cancer

We report the first results from a phase II, open-label study designed to evaluate the efficacy and safety of bevacizumab in combination with trastuzumab and capecitabine as first-line therapy for human epidermal growth factor receptor (HER)-2-positive locally recurrent (LR) or metastatic breast cancer (MBC). Patients were aged ≥18 years with confirmed breast adenocarcinoma, measurable LR/MBC and documented HER-2-positive disease. Patients received bevacizumab (15 mg/kg on day 1) plus trastuzumab (8 mg/kg on day 1 of cycle 1, 6 mg/kg on day 1 of each subsequent cycle) plus capecitabine (1,000 mg/m2 twice daily, days 1-14) every 3 weeks until disease progression, unacceptable toxicity, or consent withdrawal. Eighty-eight patients were enrolled; 40 (46%) are still on study treatment. The median follow-up was 8.8 months (range, 0.9-17.1 months). The overall response rate, the primary endpoint, was 73% (95% confidence interval [CI], 62%-82%), comprising 7% complete and 66% partial responses. The median progression-free survival interval was 14.4 months (95% CI, 10.4 months to not reached [NR]), with 35 events. The median time to progression was 14.5 months (95% CI, 10.5 months to NR), with 33 events. Treatment was well tolerated; main side effects were grade 3 hand-foot syndrome (22%), grade ≥3 diarrhea (9%), and grade ≥3 hypertension (7%). Overall, 44% of patients experienced grade ≥3 treatment-related adverse events and 13 patients discontinued capecitabine because of toxicity, but continued with bevacizumab and trastuzumab. Heart failure was seen in two patients. The combination of bevacizumab, trastuzumab, and capecitabine was clinically active as first-line therapy for patients with HER-2-positive MBC, with an acceptable safety profile and no unexpected toxicities.

P5-19-08: Pooled Analysis of Individual Patient Data from Capecitabine Monotherapy Clinical Trials in Anthracycline-/Taxane-Pretreated Locally Advanced or Metastatic Breast Cancer (LA/MBC)

Background

Capecitabine (C) has shown efficacy as monotherapy in anthracycline (A)-/taxane (T)-pretreated LA/MBC in phase II/III trials. Since its approval, the treatment landscape in MBC has evolved, and C has served as the combination partner and/or active comparator in trials of novel agents in pretreated MBC. This pooled analysis of clinical trial data, spanning a 12-yr period, assessed the efficacy and safety of C across treatment lines and the impact of disease characteristics on clinical outcomes with C.

Methods: Individual patient (pt) data were pooled from 7 clinical trials conducted by Roche/GNE from Feb 1996-Jun 2008 where C monotherapy was the test/control regimen for pts with LA/MBC with/without prior A/T therapy. Analyses were performed on an ITT basis. Univariate and multivariate regression analyses assessed the impact of pt/disease characteristics and prior therapy on outcomes.

Results: Data from 805 pts enrolled to intermittent C monotherapy were analyzed: 268 in the 1st-line metastatic setting; 537 in the ≥2nd-line metastatic setting (table).

Review of completed and ongoing trials of capecitabine-based adjuvant therapy in patients with early-stage colon cancer

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Background: Capecitabine is an established alternative to 5-FU in gastrointestinal cancers. In metastatic colorectal cancer, capecitabine is non-inferior to 5-FU and capecitabine + oxaliplatin (XELOX) is non-inferior to FOLFOX4. Capecitabine is also an effective adjuvant treatment for early-stage colon cancer. Here we review the evidence available from completed studies of adjuvant capecitabine and describe ongoing trials in this setting.

Methods: The X-ACT trial included 1,987 patients (pts) with resected stage III disease receiving either capecitabine (n=1,004) or bolus 5-FU/LV (n=983). NO16968 included 1,886 pts with resected stage III disease receiving either XELOX (n=944) or 5-FU/LV (n=942). The primary efficacy endpoint of both trials was DFS. Other large phase III trials of capecitabine in high-risk stage II/stage III pts include AVANT (XELOX + bevacizumab vs. FOLFOX4 ± bevacizumab), QUASAR2 (capecitabine vs. capecitabine + bevacizumab), SCOT (capecitabine or 5-FU/LV + oxaliplatin 12w vs. 24w), and a Japanese study of single-agent capecitabine.

Results: In X- ACT, capecitabine was at least equivalent to 5-FU/LV in terms of DFS (HR=0.88; 95% CI, 0.77–1.01) and OS (HR=0.86; 95% CI, 0.74–1.01). In a preplanned multivariate analysis, capecitabine led to significantly superior DFS (p=0.02) and OS (p=0.02) vs. bolus 5-FU/LV [Twelves et al. WCGIC 2010]. In NO16968, DFS was significantly superior for XELOX vs. 5-FU/LV (HR=0.80; 95% CI, 0.69–0.93; p=0.0045) [Haller et al. ECCO-ESMO 2009]. There was a trend towards improvement in OS with XELOX (HR=0.87; 95% CI, 0.72–1.05; p=0.1486); follow-up is ongoing. Capecitabine-based therapy had an acceptable safety profile in both trials [Twelves et al. NEJM 2005; Schmoll et al. JCO 2007]. Data have yet to be reported from the AVANT, QUASAR2, SCOT and Japanese trials, although results from these trials in over 15,000 pts are awaited with interest.

Conclusions: Adjuvant capecitabine is non-inferior to 5-FU/LV when given as monotherapy and superior to 5-FU/LV when given in combination with oxaliplatin. Capecitabine should be considered as a standard component of adjuvant treatment regimens for pts with stage III disease.

[Table: see text]

Effective management of patients receiving XELOX: Evaluation of impact of dose modifications on outcome in patients from the NO16966, NO16967, and NO16968 trials

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Background: In patients (pts) with metastatic colorectal cancer (MCRC), XELOX is non-inferior to FOLFOX4 in terms of PFS and OS as either first-line (NO16966, Cassidy et al. JCO 2008) or second-line therapy (NO16967, Rothenberg et al. Ann Oncol 2008). In pts with stage III colon cancer (NO16968, Haller et al. ECCO-ESMO 2009), adjuvant XELOX is superior to 5-FU/LV in terms of DFS. While XELOX is generally well tolerated, regional differences in fluoropyrimidine tolerability were noted in a pooled analysis [Rothenberg et al. ASCO GI 2008], leading to use of lower than recommended doses of capecitabine (i.e. 1,000mg/m2 bid d1–15 with oxaliplatin 130mg/m2 d1 q3w) in some countries.

Methods: NO16966, NO16967 and NO16968 protocols included standard dose/schedule modifications for capecitabine, 5-FU and oxaliplatin for treatment-related adverse events (AEs). Safety parameters included AEs, deaths, laboratory parameters, exposure to trial medication, and withdrawals. In NO16966 and NO16967, Kaplan-Meier curves for PFS were developed for pts with no treatment modifications, and pts with dose reductions, treatment interruptions or cycle delays to assess the effect of treatment modifications on efficacy. NO16968 also included a planned analysis of the effect of dose modifications on DFS.

Results: NO16966 included 1335 pts with previously untreated MCRC receiving XELOX or FOLFOX4. NO16967 included 627 pts with previously treated MCRC receiving XELOX or FOLFOX4. NO16968 included 1886 pts with resected stage III disease receiving XELOX or 5-FU/LV; dose modifications were required for capecitabine in 65% and oxaliplatin in 62% of pts in NO16968. Kaplan-Meier curves of PFS (NO16966/NO16967) or DFS (NO16968) for pts who did and did not require dose modifications indicated that the efficacy of XELOX did not appear to be compromised by dose modifications. Indeed, pts who required dose modifications seemed to have a favourable outcome compared with those who did not.

Conclusions: From these data we cannot make a recommendation that initial dosing should be lower than the labeled dose. However, it is clear that dose modification does not seem to impact patient outcome.

[Table: see text]