Immunochemotherapy plus lenalidomide for high-risk mantle cell lymphoma with measurable residual disease evaluation

Chemoimmunotherapy followed by consolidative high-dose therapy with autologous stem cell rescue was a standard upfront treatment for fit patients with mantle cell lymphoma (MCL) in first remission; however, treatment paradigms are evolving in the era of novel therapies. Lenalidomide is an immunomodulatory agent with known efficacy in treating MCL. We conducted a single-center, investigator-initiated, phase II study of immunochemotherapy incorporating lenalidomide, without autologous stem cell transplant consolidation, enriching for patients with high-risk MCL (clinicaltrials gov. Identifier: NCT02633137). Patients received four cycles of lenalidomide-R-CHOP, two cycles of R-HiDAC, and six cycles of R-lenalidomide. The primary endpoint was rate of 3-year progression-free survival. We measured measurable residual disease (MRD) using a next-generation sequencing-based assay after each phase of treatment and at 6 months following end-oftreatment. We enrolled 49 patients of which 47 were response evaluable. By intent-to-treat, rates of overall and complete response were equivalent at 88% (43/49), one patient with stable disease, and two patients had disease progression during study; 3-year progression-free survival was 63% (primary endpoint not met) and differed by TP53 status (78% wild-type vs. 38% ALT; P=0.043). MRD status was prognostic and predicted long-term outcomes following R-HiDAC and at 6 months following end-of-treatment. In a high-dose therapy-sparing, intensive approach, we achieved favorable outcomes in TP53- wild-type MCL, including high-risk cases. We confirmed that sequential MRD assessment is a powerful prognostic tool in patients with MCL.

Phase I study of bendamustine, rituximab, ibrutinib, and venetoclax in relapsed, refractory mantle cell lymphoma

This dose-finding study evaluated safety of venetoclax plus Bendamustine-Rituximab-Ibrutinib in relapsed/refractory MCL. Six 28-day cycles were administered in a 3 + 3 dose-escalation design. Dose level 1 (DL1) included Bendamustine 90 mg/m2 on day 1-2, Rituximab 375 mg/m2 on day 1, and Ibrutinib 560 mg daily. Venetoclax was dosed with ramp-up and at 400 mg starting in Cycle 2 for 5 days. The most common adverse events were thrombocytopenia (80%), constipation (60%), and fatigue (60%). Rare hematologic grade 3-4 AEs, 1 dose-limiting toxicity at DL1 (prolonged grade 3 thrombocytopenia), and delayed hematologic toxicity were observed. DL-1 with Bendamustine dose-reduced to 70 mg/m2 (n = 3) revealed no significant toxicity. The overall and complete response rates were both 80% (8/10). This study underscored that venetoclax combined with chemoimmunotherapy is complicated by hematologic toxicity, limiting future development. Although a maximum tolerated dose was not formally established given early study closure, this study demonstrated preliminary tolerability and efficacy of Bendamustine-Rituximab-Ibrutinib-Venetoclax at DL-1.

Standard-of-care systemic therapy with or without stereotactic body radiotherapy in patients with oligoprogressive breast cancer or non-small-cell lung cancer (Consolidative Use of Radiotherapy to Block [CURB] oligoprogression): an open-label, randomised, controlled, phase 2 study

BACKGROUND

Most patients with metastatic cancer eventually develop resistance to systemic therapy, with some having limited disease progression (ie, oligoprogression). We aimed to assess whether stereotactic body radiotherapy (SBRT) targeting oligoprogressive sites could improve patient outcomes.

METHODS

We did a phase 2, open-label, randomised controlled trial of SBRT in patients with oligoprogressive metastatic breast cancer or non-small-cell lung cancer (NSCLC) after having received at least first-line systemic therapy, with oligoprogression defined as five or less progressive lesions on PET-CT or CT. Patients aged 18 years or older were enrolled from a tertiary cancer centre in New York, NY, USA, and six affiliated regional centres in the states of New York and New Jersey, with a 1:1 randomisation between standard of care (standard-of-care group) and SBRT plus standard of care (SBRT group). Randomisation was done with a computer-based algorithm with stratification by number of progressive sites of metastasis, receptor or driver genetic alteration status, primary site, and type of systemic therapy previously received. Patients and investigators were not masked to treatment allocation. The primary endpoint was progression-free survival, measured up to 12 months. We did a prespecified subgroup analysis of the primary endpoint by disease site. All analyses were done in the intention-to-treat population. The study is registered with ClinicalTrials.gov, NCT03808662, and is complete.

FINDINGS

From Jan 1, 2019, to July 31, 2021, 106 patients were randomly assigned to standard of care (n=51; 23 patients with breast cancer and 28 patients with NSCLC) or SBRT plus standard of care (n=55; 24 patients with breast cancer and 31 patients with NSCLC). 16 (34%) of 47 patients with breast cancer had triple-negative disease, and 51 (86%) of 59 patients with NSCLC had no actionable driver mutation. The study was closed to accrual before reaching the targeted sample size, after the primary efficacy endpoint was met during a preplanned interim analysis. The median follow-up was 11·6 months for patients in the standard-of-care group and 12·1 months for patients in the SBRT group. The median progression-free survival was 3·2 months (95% CI 2·0-4·5) for patients in the standard-of-care group versus 7·2 months (4·5-10·0) for patients in the SBRT group (hazard ratio [HR] 0·53, 95% CI 0·35-0·81; p=0·0035). The median progression-free survival was higher for patients with NSCLC in the SBRT group than for those with NSCLC in the standard-of-care group (10·0 months [7·2-not reached] vs 2·2 months [95% CI 2·0-4·5]; HR 0·41, 95% CI 0·22-0·75; p=0·0039), but no difference was found for patients with breast cancer (4·4 months [2·5-8·7] vs 4·2 months [1·8-5·5]; 0·78, 0·43-1·43; p=0·43). Grade 2 or worse adverse events occurred in 21 (41%) patients in the standard-of-care group and 34 (62%) patients in the SBRT group. Nine (16%) patients in the SBRT group had grade 2 or worse toxicities related to SBRT, including gastrointestinal reflux disease, pain exacerbation, radiation pneumonitis, brachial plexopathy, and low blood counts.

INTERPRETATION

The trial showed that progression-free survival was increased in the SBRT plus standard-of-care group compared with standard of care only. Oligoprogression in patients with metastatic NSCLC could be effectively treated with SBRT plus standard of care, leading to more than a four-times increase in progression-free survival compared with standard of care only. By contrast, no benefit was observed in patients with oligoprogressive breast cancer. Further studies to validate these findings and understand the differential benefits are warranted.

FUNDING

National Cancer Institute.

Bendamustine in combination with ofatumumab as first line treatment for elderly patients with mantle cell lymphoma: a phase II risk-adapted design

This study evaluated ofatumumab (Ofa), an anti-CD20 monoclonal antibody, alone or with bendamustine (Benda), in transplant-ineligible patients with mantle cell lymphoma. Low-risk patients received Ofa monotherapy. Non-responders received subsequent treatment with Benda-Ofa. Six patients received Ofa monotherapy and 3 patients crossed over to Bend-Ofa. Twenty-four high-risk patients were initially treated with Benda-Ofa. The overall response rate for patients treated with Ofa monotherapy was 1/6 (17%) and 23/25 (92%) for patients treated with Benda-Ofa. With a median follow-up of 8.6 years, all Ofa patients progressed with a median progression-free survival (PFS) of 0.6 years (95% CI 0.31-NR) and remain alive. With a median follow-up of 6.3 years, Bend-Ofa treated patients had median PFS 2.5 years (95% CI 1.8-NR) and a median overall survival of 7.4 years (95% CI 5.8-NR). Benda-Ofa had a favorable adverse event profile and efficacy similar, but not clearly superior, to those reported for Benda-Rituximab.

Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple-negative breast cancer: a feasibility study

PURPOSE

Chemotherapy with or without immunotherapy remains the mainstay of treatment for triple-negative breast cancer (TNBC). A subset of TNBCs express the androgen receptor (AR), representing a potential new therapeutic target. This study assessed the feasibility of adjuvant enzalutamide, an AR antagonist, in early-stage, AR-positive (AR +) TNBC.

METHODS

This study was a single-arm, open-label, multicenter trial in which patients with stage I-III, AR ≥ 1% TNBC who had completed standard-of-care therapy were treated with enzalutamide 160 mg/day orally for 1 year. The primary objective of this study was to evaluate the feasibility of 1 year of adjuvant enzalutamide, defined as the treatment discontinuation rate of enzalutamide due to toxicity, withdrawal of consent, or other events related to tolerability. Secondary endpoints included disease-free survival (DFS), overall survival (OS), safety, and genomic features of recurrent tumors.

RESULTS

Fifty patients were enrolled in this study. Thirty-five patients completed 1 year of therapy, thereby meeting the prespecified trial endpoint for feasibility. Thirty-two patients elected to continue with an optional second year of treatment. Grade ≥ 3 treatment-related adverse events were uncommon. The 1-year, 2-year, and 3-year DFS were 94%, 92% , and 80%, respectively. Median OS has not been reached.

CONCLUSION

This clinical trial demonstrates that adjuvant enzalutamide is a feasible and well-tolerated regimen in patients with an early-stage AR + TNBC. Randomized trials in the metastatic setting may inform patient selection through biomarker development; longer follow-up is needed to determine the effect of anti-androgens on DFS and OS in this patient population.

Alpelisib (ALP) + endocrine therapy (ET) in patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–), PIK3CA-mutated (mut) advanced breast cancer (ABC): Baseline biomarker analysis and progression-free survival (PFS) by duration of prior cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy in the BYLieve study

1018

Background: ALP (PI3K-α selective inhibitor and degrader) + fulvestrant (FUL) is approved for pts with HR+, HER2– ABC and a tumor mutation in PIK3CA (̃ 40% of these pts). Primary analyses from the Phase 2 BYLieve study demonstrated efficacy and safety of ALP + ET in pts with PIK3CA-mut, HR+, HER2– ABC in the post-CDK4/6i setting. Post hoc analyses, including pts with disease progression within 6 mo of CDK4/6i + ET treatment (Tx), confirmed ALP benefit regardless of duration of prior CDK4/6i. Here we assess baseline biomarkers in circulating tumor DNA (ctDNA) by duration of prior CDK4/6i Tx and PFS in pts from BYLieve Cohorts A and B. Methods: In the BYLieve study, pts with PIK3CA-mut, HR+, HER2– ABC had CDK4/6i + aromatase inhibitor (Cohort A) or + FUL (Cohort B) as immediate prior Tx to receiving ALP + FUL and ALP + letrozole (LET), respectively. At data cutoff dates, pts had ≥ 18-mo follow-up in Cohort A and ≥ 6-mo in Cohort B. In each cohort, pts were grouped based on duration of prior CDK4/6i Tx (≤ 6 mo or >6 mo). Alterations were detected on ctDNA using next-generation sequencing (PanCancer V2 Panel). PFS was assessed in each cohort and by duration of prior CDK4/6i Tx. Results: Of 127 and 126 pts enrolled in Cohorts A and B, respectively, 98 (≤ 6-mo: 24; >6-mo: 74) and 94 (≤ 6-mo: 28; >6-mo: 66) were included in this analysis based on availability of ctDNA samples, data on duration of prior CDK4/6i, and centrally confirmed PIK3CA-mut disease. In this population, median (m) PFS (95% CI) was 8.2 mo (5.6 - 9.5) and 5.6 mo (3.7 - 7.1) in Cohorts A and B, respectively. In Cohort A, mPFS (95% CI) was 12.0 mo (5.5-non estimable) and 6.2 mo (5.4 - 8.5) in the ≤ 6-mo and >6-mo groups, respectively. The OncoPrint genomic profiles showed that pts in the ≤ 6-mo vs >6-mo group had a lower median ctDNA fraction and fewer detected gene alterations, including in genes associated with ET and/or CDK4/6i resistance, and fewer chromosomes 8/11 amplifications (linked to early relapse). In Cohort B, mPFS was 5.9 mo (3.5 - 11.0) and 5.6 mo (3.7 - 7.1) in the ≤ 6-mo and >6-mo groups, respectively. Both groups had high median ctDNA fractions and complex tumor mutation profiles reflecting more extensive treatment history. Conclusions: Lower median ctDNA fraction and lower mutational complexity observed in Cohort A ≤ 6-mo vs >6-mo group was associated with numerically longer mPFS, potentially indicating increased dependence on the mutant PI3K-α. In Cohort B, both ≤ 6-mo and >6-mo groups had high median ctDNA fractions and similar tumor mutation profiles. Additional ctDNA and tissue analyses are needed to elucidate the correlation between ALP + ET efficacy and treatment timing and baseline genomic complexity.

Abstract P5-13-03: Alpelisib + endocrine therapy (ET) in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), PIK3CA-mutated advanced breast cancer (ABC) previously treated with cyclin-dependent kinase 4/6 inhibitor (CDK4/6i): Biomarker analyses from the Phase II BYLieve study

Introduction: Alpelisib (ALP, a PI3Kα inhibitor and degrader) + ET has demonstrated efficacy in patients (pts) with HR+, HER2-, PIK3CA-mutated ABC progressing on/after CDK4/6i + ET in the ongoing Phase II BYLieve study (NCT03056755). The primary endpoint, in pts with centrally confirmed PIK3CA mutation in tumor tissue (modified full analysis set [mFAS]), was met in Cohorts A (ALP + fulvestrant [FUL]) and B (ALP + letrozole [LET]) with 50.4% (95% CI, 41.2%-59.6%) of 121 pts and 46.1% (36.8%-55.6%) of 115 pts alive and without disease progression at 6 mo, respectively. Activating PIK3CA mutations, occurring in ~40% of tumors, confer worse prognosis in the advanced setting. Here, we assess the correlation between progression-free survival (PFS) and other baseline biomarkers among pts in BYLieve Cohorts A and B. Methods: Enrolled pre-/postmenopausal women with HR+, HER2-, PIK3CA-mutated ABC received CDK4/6i + aromatase inhibitor (Cohort A) or FUL (Cohort B), as immediate prior treatment (Tx). Pts received ALP 300 mg PO QD + FUL 500 mg IM Q28D and C1D15 (Cohort A) or ALP 300 mg PO QD + LET 2.5 mg PO QD (Cohort B) as study Tx. This exploratory analysis of baseline biomarkers identified gene alterations using an error-connected sequencing ctDNA assay (Novartis PanCancer gene-panel) in plasma samples from pts with a centrally confirmed PIK3CA mutation in tumor tissue from Cohorts A and B. PFS was estimated using the Kaplan-Meier method in subgroups of pts based on high (≥10%) or low (<10%) ctDNA fraction, high (≥10) or low (<10) tumor mutation burden (TMB), and amplification (amp) status of chromosomes (chr) 8 or 11 amplicons (frequently observed in breast cancer and usually associated with early relapse). Results: In Cohorts A and B, 102 of 127 enrolled pts and 97 of the 126 enrolled pts were included in this analysis, respectively. In this analysis, median PFS (mPFS) was 7.3 mo in Cohort A and 5.7 mo in Cohort B, consistent with observations in the mFAS (Table 1). Pts with a low ctDNA fraction or TMB at baseline had longer mPFS than pts with high ctDNA fraction or TMB (Table 1). In addition to PIK3CA alterations observed in 73% of tumors from pts in Cohorts A and B, the most frequently altered genes in the studied population were ESR1 (27% and 28%) and TP53 (25% and 26%) in Cohorts A and B, respectively. Across both cohorts, pts whose tumors had loss of function alterations in genes known to mediate resistance to CDK4/6i (PTEN, RB1, CHD4, FAT1, NF1, ATM, CDKN2A-C) derived clinical benefit (partial response or stable disease) from ALP + ET. Amp of known amplicons on chr 8 (eg, FGFR1, TACC1) or 11 (eg, CCND1, FGF3, FGF4) were observed in 5%-8% of pts in Cohort A and 8%-11% of pts in Cohort B. Pts whose tumors had no gene amp on chr 8 and/or 11 had longer mPFS than pts whose tumors had an amp (Table 1). Similar results were observed when analyzing chr 8 (6.33 mo vs 4.92 mo) and chr 11 (6.33 mo vs 4.63 mo) separately in pts from Cohorts A plus B. Conclusion: In pts with HR+, HER2-, PIK3CA-mutated ABC, ALP was effective in the post-CDK4/6i setting regardless of ET partner and tumor genomic profile (including in presence of alterations in genes associated with CDK4/6i resistance). The absence of cross-resistance may allow pts with PIK3CA-mutated disease to benefit from ALP after disease progression on/after CDK4/6i.

Table 1.mPFS in pts from BYLieve Cohorts A and B based on baseline biomarker statusCohort A (ALP + FUL)Cohort B (ALP + LET)nmPFS, mo (95% CI) nmPFS, mo (95% CI)Overall (mFASa)1,21217.3 (5.6-8.3)1155.7 (4.5-7.2)Patients with available plasma sample for the biomarker analysisb1027.37 (5.60-8.67)975.70 (3.77-7.33)ctDNA fractionHigh (≥10%)655.60 (4.00-7.37)685.43 (3.70-7.20)Low (<10%)37NE297.33 (5.83-11.00)TMBHigh (≥10)103.85 (0.47-8.33)154.60 (1.67-5.73)Low (<10)716.13 (5.43-9.60)645.63 (3.73-7.50)Chr 8 or 11 amplificationWith174.23 (1.70-6.13)213.77 (1.93-7.37)Without858.40 (5.70-9.60)766.00 (5.20-7.53)Chr, chromosome; ctDNA, circulating tumor DNA; NE, not estimable; mPFS, median progression-free survival; TMB, tumor mutation burden. aPatients who received at least 1 dose of study treatment and had centrally confirmed PIK3CA mutation by a Novartis-designated laboratory were included in the mFAS. bOnly includes patients with centrally confirmed PIK3CA mutation in tumor tissue. 1. Rugo HS, et al. Lancet Oncol. 2021;22(4):489-498; 2. Rugo HS, et al. SABCS 2020. Poster PD2-07.

Citation Format: Dejan Juric, Nicholas Turner, Aleix Prat, Stephen Chia, Eva M Ciruelos, Manuel Ruiz-Borrego, Pamela Drullinsky, Florence Lerebours, Thomas Bachelot, O. Alejandro Balbin, Mukta Joshi, Estelle Roux, Christina H Arce, Murat Akdere, Hope S Rugo. Alpelisib + endocrine therapy (ET) in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), PIK3CA-mutated advanced breast cancer (ABC) previously treated with cyclin-dependent kinase 4/6 inhibitor (CDK4/6i): Biomarker analyses from the Phase II BYLieve study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-13-03.

Abstract P1-18-08: Effect of duration of prior cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy (≤6 mo or >6 mo) on alpelisib benefit in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), PIK3CA-mutated advanced breast cancer (ABC) from BYLieve

Introduction: PIK3CA (encoding phosphatidylinositol 3-kinase alpha [PI3Kα]) is a driver oncogene mutated (mut) in ~40% of HR+, HER2- ABCs, leading to endocrine therapy (ET) resistance and poor prognosis. Alpelisib (ALP) is the first oral α-selective PI3K inhibitor and degrader approved in this patient (pt) population. Primary analyses of Cohorts A and B from BYLieve, an ongoing Phase II noncomparative study, demonstrated efficacy and a consistent safety profile of ALP + ET (fulvestrant [FUL] or letrozole [LET]) in pts with PIK3CA-mut, HR+, HER2- ABC in the post CDK4/6i setting. Post hoc analyses of ALP benefit in pts with centrally confirmed PIK3CA mut, based on median duration of prior CDK4/6i, supported the efficacy of ALP + ET in CDK4/6i-resistant, HR+, HER2- ABC. Here we assessed whether those who achieved a short duration of disease control (6-month [mo] cutoff), with prior CDK4/6i + ET received clinical benefit with ALP + ET. Methods: In Cohorts A and B, pts with PIK3CA-mut, HR+, HER2- ABC had received CDK4/6i + aromatase inhibitor (AI) or FUL, respectively, as immediate prior therapy (majority in first line). Pts in Cohort A received ALP 300 mg PO QD + FUL 500 mg IM Q28D + C1D15; pts in Cohort B received ALP 300 mg PO QD + LET 2.5 mg PO QD. Within each cohort, pts were divided based on duration of prior CDK4/6i therapy (≤6 mo or >6 mo), and the association of progression-free survival (PFS) with this covariate was analyzed using a stratified log-rank test and Cox Proportional Hazards model. A 6-mo cutoff was selected based on the ESO-ESMO ABC5 cutoff for primary ET resistance, as current guidelines do not specify cutoffs for CDK4/6i resistance. This analysis is based on the PFS endpoint and included pts for whom duration of prior CDK4/6i therapy was known. Results: Of the 121 pts in Cohort A with centrally confirmed PIK3CA-mut disease (modified full analysis set, mFAS), 120 had duration of prior CDK4/6i available; 26 had CDK4/6i for ≤6 mo and 94 for >6 mo, with similar demographics/disease characteristics between subgroups. The hazard ratio (HR) of median PFS (mPFS) between the ≤6-mo group and >6-mo group was 0.50 (95% confidence interval [CI], 0.27-0.94), indicating a lower risk of progression in the ≤6-mo group, with mPFS 10.0 mo (95% CI, 5.55-not estimable) and 6.0 mo (95% CI, 5.16-8.31), respectively. Grade ≥3 adverse events (AEs) were experienced by 67.5% (n=85) of all pts (safety set) in Cohort A and by 76.9% (n=20)/65.0% (n=65) in the ≤6-mo/>6-mo subgroups, respectively. Of the 115 pts in Cohort B with centrally confirmed PIK3CA-mut disease (mFAS), 113 had duration of prior CDK4/6i available; 31 had CDK4/6i for ≤6 mo and 82 for >6 mo, with similar demographics/disease characteristics between subgroups. The HR of mPFS between the ≤6-mo and >6-mo groups was 0.76 (95% CI, 0.47-1.23), with the wide CI indicating no difference in risk of progression between subgroups, and mPFS was 5.9 mo (95% CI, 3.55-10.97) and 5.6 mo (95% CI, 3.68-7.10), respectively. Grade ≥3 AEs were experienced by 69.9% (n=86) of all pts (safety set) in Cohort B and by 63.6% (n=21)/72.2% (n=65) in the ≤6-mo/>6-mo subgroups, respectively. Conclusions: This demonstrates that pts with PIK3CA-mut, HR+, HER2- ABC who achieved ≤6-mo duration of disease control with prior CDK4/6i had a numerically longer PFS in Cohort A, and almost the same clinical efficacy in Cohort B, to ALP + ET vs pts with >6-mo duration of disease control, with a comparable safety profile. This confirms targeting PI3Kα with ALP provides clinical benefit in pts with CDK4/6i-resistant ABC, including early progressors, and supports consideration of ALP + ET as an immediate next-line option in this setting, possibly delaying chemotherapy.

Citation Format: Stephen Chia, Eva M Ciruelos, Hope S Rugo, Florence Lerebours, Manuel Ruiz-Borrego, Pamela Drullinsky, Aleix Prat, Thomas Bachelot, Nicholas Turner, Ennan Gu, Christina Arce, Murat Akdere, Dejan Juric. Effect of duration of prior cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy (≤6 mo or >6 mo) on alpelisib benefit in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), PIK3CA-mutated advanced breast cancer (ABC) from BYLieve [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-18-08.

Abstract PD15-01: Impact of ESR1 mutations on endocrine therapy (ET) plus alpelisib benefit in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), PIK3CA-mutated, advanced breast cancer (ABC) who progressed on or after prior cyclin-dependent kinase inhibitor (CDK4/6i) therapy in the BYLieve trial

Introduction: Endocrine-based therapy is the standard of care for patients (pts) with HR+ ABC. Acquired ESR1 mutations (mut) have been reported in up to 56% of pts with HR+ ABC progressing after prior treatment with ET, and aromatase inhibitors (AIs) in particular. Alpelisib (ALP) is an α-selective PI3K inhibitor and degrader approved in combination with fulvestrant (FUL) for the treatment of HR+, HER2-, PIK3CA-mut ABC. The primary analysis of Cohorts A and B of the Phase II BYLieve trial demonstrated the safety and efficacy of ALP + ET in the post-CDK4/6i setting. We assessed the association between progression-free survival (PFS) and baseline ESR1 mut among pts in Cohorts A and B of the BYLieve trial. Methods: Cohorts A and B of the BYLieve trial included pre-/postmenopausal women with HR+, HER2-, PIK3CA-mut ABC who received CDK4/6i + AI (Cohort A) or CDK4/6i + FUL (Cohort B) as immediate prior therapy. Pts in Cohort B may have also received prior AI therapy. Pts received ALP 300 mg PO QD + FUL 500 mg IM Q28D and C1D15 (Cohort A) or ALP 300 mg PO QD + LET 2.5 mg PO QD (Cohort B). ESR1 mut was analyzed as an exploratory endpoint, using an error-corrected sequencing ctDNA assay (Novartis PanCancer gene-panel), in baseline plasma samples from pts with centrally confirmed PIK3CA mut in tumor tissue from Cohorts A and B. PFS by mut status was estimated using the Kaplan-Meier method. P values provided are nominal. No multiplicity adjustments were made, therefore, statistical interpretation should be made with caution. Results: 127 pts with ≥6 mo follow-up (median follow-up: 11.7 mo) were enrolled in Cohort A as of the 17 December 2019 data cut-off and 126 pts with ≥6 mo follow-up (median follow-up: 15.0 mo) were enrolled in Cohort B as of the 14 August 2020 data cut-off. 103 (81.7%) pts in Cohort B progressed on prior AI therapy (adjuvant/metastatic setting). 102 pts from Cohort A and 97 pts from Cohort B had available plasma samples and were included in this analysis. Similar outcomes were observed in this analysis and in the overall population (Table 1). At baseline, 26% (27/102) of pts in Cohort A and 26% (25/97) of pts in Cohort B had ESR1 mut detected. In Cohort A (ALP + FUL), a numerically lower PFS was observed in pts with ESR1-mut disease, but the wide confidence interval (CI) suggests no difference in risk of progression between those with and without ESR1 mut. In Cohort B (ALP + LET), pts with ESR1-mut disease had a shorter PFS compared with those without ESR1-mut disease. A possible limitation is that baseline characteristics of these subgroups may not be balanced.

Conclusion: Similar proportion of pts had ESR1-mut disease at baseline in both cohorts. All pts in Cohort A progressed on prior CDK4/6i + AI and most pts enrolled in Cohort B also progressed on prior AI therapy. This analysis suggests that pts with ESR1 mut tend to have lower PFS than those without a mut, and that ALP + LET might be less effective in pts with ESR1 mut. This adds to prior data that ESR1 mut reduce the efficacy of AI-based combination therapy. In pts with ESR1 mut detected after prior CDK4/6i therapy, ALP + FUL (the approved combination for PIK3CA-mut ABC) warrants consideration as an alternative treatment option. Studies of ALP in combination with new oral, selective estrogen-receptor degraders are also ongoing.

Table 1.Median PFS in BYLieve Cohorts A and B.Cohort A (ALP + FUL)Cohort B (ALP + LET)Overall (mFASa), N1,2121115mPFS, months (95% CI)7.3 (5.6-8.3)5.7 (4.5, 7.2)Patients with available plasma samples for ESR1-mutation testing,b N10297mPFS, months (95% CI)7.37 (5.60-8.67)5.70 (3.77-7.33)With ESR1 mutation (n=27)With ESR1 mutation (n=25) Without ESR1 mutation (n=72)mPFS, months (95% CI)5.55 (3.75-8.54)8.28 (5.45-9.46)4.57 (3.06-5.65)7.03 (4.50-8.31)Hazard ratio (95% CI)0.76 (0.44-1.33)0.55 (0.32-0.92)P value (nominal)0.30.02ALP, alpelisib; FUL, fulvestrant; LET, letrozole; mFAS, modified full analysis set; mPFS, median progression-free survival. . aPatients who received at least 1 dose of study treatment and had centrally confirmed PIK3CA mutation by a Novartis-designated laboratory were included in the mFAS. bOnly includes patients with centrally confirmed PIK3CA mutation in tumor tissue.1. Rugo HS, et al. Lancet Oncol. 2021;22(4):489-498; 2. Rugo HS, et al. SABCS 2020. Poster PD2-07.

Citation Format: Nick Turner, Hope S Rugo, Eva M Ciruelos, Manuel Ruiz-Borrego, Pamela Drullinsky, Florence Lerebours, Aleix Prat, Thomas Bachelot, Stephen Chia, Alejandro Balbin, Mukta Joshi, Estelle Roux, Christina H Arce, Murat Akdere, Dejan Juric. Impact of ESR1 mutations on endocrine therapy (ET) plus alpelisib benefit in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), PIK3CA-mutated, advanced breast cancer (ABC) who progressed on or after prior cyclin-dependent kinase inhibitor (CDK4/6i) therapy in the BYLieve trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD15-01.

Abstract P1-14-03: Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple negative breast cancer: A feasibility study

Background: Chemotherapy remains the mainstay of treatment for early-stage triple negative breast cancer (TNBC), yet targetable drivers of interest are under investigation. A subset of TNBCs express the androgen receptor (AR) and exhibit androgen-dependent growth. The AR-antagonist enzalutamide (ENZA) has shown activity in patients with metastatic AR+ TNBC. In this study, the feasibility of adjuvant ENZA in early-stage, AR+ TNBC was assessed (NCT02750358). As reported previously, this study met its primary endpoint of feasibility (Traina et al., ASCO 2019). Here we report secondary survival endpoints. Methods: In this single-arm, open-label, multi-center trial, patients with stage I-III, AR≥1% TNBC (ER/PR <1%, HER2 negative) who had completed standard of care therapy were treated with ENZA 160 mg/day orally for 1 year. Patients who completed 1 year had an option to remain on adjuvant ENZA for another year. Toxicity was graded using National Cancer Institute Common Toxicity Criteria (NCI CTCAE) v4. The primary endpoint of this study was to evaluate feasibility of adjuvant ENZA, defined as the discontinuation rate due to toxicity, withdrawal of consent, other events related to tolerability or patient preference. The study was designed to discriminate between feasibility rates of 50% and 70% and was considered feasible if ≥29 out of 46 patients received ENZA for one year without discontinuation. Secondary endpoints included DFS, OS, safety, patient reported outcomes and correlative science. Patients who had disease progression (PD) during year 1 of ENZA without treatment discontinuation due to the above reasons were not included in the primary feasibility analysis but were included in secondary endpoint analyses for survival. Results: 50 patients enrolled on study from 05/2016 - 06/2018. The median age was 58 years (range 34-81 years); 8% had a germline BRCA1/2 (n=3) or PALB2 (n=1) mutation. 38% had stage I disease at diagnosis, 48% stage II and 14% stage III. 74% had grade 3 tumors. 94% of all patients received prior systemic chemotherapy, 81% of whom received prior anthracycline-taxane. 38% (n=19) were treated with prior neoadjuvant chemotherapy and 32% of those patients (n=6) achieved a pCR. Of those who did not achieve a pCR, 69% received adjuvant capecitabine. 47 patients were evaluable for the study endpoint and 35 patients completed 1 year of ENZA thereby meeting the prespecified trial endpoint for feasibility. 32 patients elected to continue into a second year of treatment. After a median follow-up of 140 weeks (range 4 - 236 weeks), 8 patients had a DFS event: 7 TNBC recurrences and 1 new primary breast cancer. The 1-year DFS was 94% (95% CI: 87 - 100%), 2-year DFS was 92% (95% CI: 84 - 99.8%) and the 3-year DFS was 80% (95% CI: 67 - 94%). The median DFS and OS have not yet been reached. Two patients died of TNBC recurrence after 55 and 59 weeks. There were no new or unexpected toxicities observed at study completion. Conclusion: This single-arm trial previously met its primary endpoint of feasibility in patients with early-stage AR+ TNBC. In this relatively high-risk, albeit highly selected patient population, the 3-year DFS measured 80% (95% CI: 67 - 94%) with an adjuvant endocrine therapy approach. Efforts to determine the optimal biomarker for AR+ TNBC are ongoing, so that patients most likely to respond to AR-antagonists in both the early and metastatic setting may be identified. Biomarker data from this study including PD-L1 status and tumor sequencing will be reported at the time of presentation.Funding and drug support for this study was provided by Astellas Pharma Global Development Inc./Pfizer Inc.

Citation Format: Elaine M Walsh, Ayca Gucalp, Sujata Patil, Marcia Edelweiss, Dara S Ross, Pedram Razavi, Shanu Modi, Neil M Iyengar, Rachel Sanford, Tiffany Troso-Sandoval, Mila Gorsky, Jackie Bromberg, Pamela Drullinsky, Diana Lake, Serena Wong, Patricia DeFusco, Nicholas Lamparella, Ranja Gupta, Tasmila Tabassum, Leigh Ann Boyle, Artavazd Arumov, Tiffany A Traina. Adjuvant enzalutamide for the treatment of early-stage androgen-receptor positive, triple negative breast cancer: A feasibility study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-14-03.

Morphological and genomic characteristics of breast cancers occurring in individuals with Lynch Syndrome

PURPOSE

Lynch syndrome (LS) is defined by germline pathogenic mutations involving DNA Mismatch Repair (MMR) genes and linked with the development of MMR-deficient (MMRd) colon and endometrial cancers. Whether breast cancers (BC) developing in context of LS are causally related to MMR deficiency (MMRd), remains controversial. Thus, we explored the morphological and genomic characteristics of BCs occurring in LS individuals.

EXPERIMENTAL DESIGN

A retrospective analysis of 20,110 cancer patients who underwent multigene panel genetic testing was performed to identify individuals with a likely pathogenic/pathogenic germline variant in MLH1, MSH2, MSH6 or PMS2 who developed BCs. The histological characteristics and immunohistochemical (IHC) assessment of BCs for MMR proteins and programmed death-ligand 1 (PD-L1) expression were assessed on cases with available materials. DNA samples from paired tumors and blood were sequenced with MSK-IMPACT ({greater than or equal to}468 key cancer genes). MSI status was assessed utilizing MSISensor. Mutational signatures were defined using SigMA.

RESULTS

272 LS individuals were identified, 13 (5%) of whom had primary BCs. The majority of BCs (92%) were hormone receptor positive tumors. Five (42%) of 12 BCs displayed loss of MMR proteins by IHC. Four (36%) of 11 BCs subjected to tumor-normal sequencing showed dominant microsatellite instability mutational signatures, high tumor mutational burden and indeterminate (27%) or high MSISensor scores (9%). One patient with metastatic MMRd BC received anti-PD1 therapy and achieved a robust and durable response.

CONCLUSIONS

A subset of BCs developing in LS individuals are etiologically linked to MMRd and may benefit from anti-PD1/PD-L1 immunotherapy.

Phase I/Ib Study of the Efficacy and Safety of Buparlisib and Ibrutinib Therapy in MCL, FL, and DLBCL with Serial Cell-Free DNA Monitoring

PURPOSE

Activation of Bruton tyrosine kinase (BTK) and phosphatidylinositol-3-kinase (PI3K) represent parallel, synergistic pathways in lymphoma pathogenesis. As predominant PI3Kδ inhibition is a possible mechanism of tumor escape, we proposed a clinical trial of dual BTK and pan-PI3K inhibition.

PATIENTS AND METHODS

We conducted a single-center phase I/Ib trial combining a BTK inhibitor (ibrutinib) and a pan-PI3K inhibitor (buparlisib) in 37 patients with relapsed/refractory (R/R) B-cell lymphoma. Buparlisib and ibrutinib were administered orally, once daily in 28-day cycles until progression or unacceptable toxicity. The clinical trial is registered with clinicaltrials.gov, NCT02756247.

RESULTS

Patients with mantle cell lymphoma (MCL) receiving the combination had a 94% overall response rate (ORR) and 33-month median progression-free survival; ORR of 31% and 20% were observed in patients with diffuse large B-cell lymphoma and follicular lymphoma, respectively. The maximum tolerated dose was ibrutinib 560 mg plus buparlisib 100 mg and the recommended phase II dose was ibrutinib 560 mg plus buparlisib 80 mg. The most common grade 3 adverse events were rash/pruritis/dermatitis (19%), diarrhea (11%), hyperglycemia (11%), and hypertension (11%). All grade mood disturbances ranging from anxiety, depression, to agitation were observed in 22% of patients. Results from serial monitoring of cell-free DNA samples corresponded to radiographic resolution of disease and tracked the emergence of mutations known to promote BTK inhibitor resistance.

CONCLUSIONS

BTK and pan-PI3K inhibition in mantle cell lymphoma demonstrates a promising efficacy signal. Addition of BCL2 inhibitors to a BTK and pan-PI3K combination remain suitable for further development in mantle cell lymphoma.

Update of a phase II, multicenter study of high-dose chemotherapy with autologous stem cell transplant followed by maintenance romidepsin for T-cell lymphoma

7533

Background: Peripheral T-cell lymphomas (PTCL) have suboptimal outcomes with conventional chemotherapy. Autologous hematopoietic stem cell transplant (AHCT) is a therapeutic strategy for patients in first complete or partial remission (CR1 or PR1), with median progression-free survival (PFS) after AHCT of 36-48% by intent to treat (d’Amore et al JCO 2012, Reimer et al JCO 2009). Romidepsin (romi) is a histone deacetylase inhibitor approved for treatment of relapsed/refractory T-cell lymphoma. We present updated data of the first multicenter study to evaluate PFS of patients (pts) receiving maintenance therapy with romi after AHCT. Methods: This was a phase 2, open-label, investigator-initiated study (expected PFS 45%, desired PFS 70%; success achieved if 15 or more pts out of 25 were progression-free at 2 years post-AHCT). 26 pts transplanted in CR1 or PR1 were evaluable for the primary endpoint of 2-year PFS (Cohort 1, Table). An exploratory cohort (Cohort 2, n=7) enrolled pts either transplanted ≥ CR/PR2 (n=5) or with high risk histologies (n=2). Pts underwent AHCT with carmustine, etoposide, cytarabine and melphalan (BEAM) conditioning. Maintenance romi 14 mg/m2 started days 42-80 post AHCT; every other week through 6 mon, every 3 weeks through 1 year and every 4 weeks through 2 years post AHCT. PFS was estimated by Kaplan-Meier. Results: 47 pts consented; 13 did not receive romi (no AHCT, n=2; relapse before romi, n=3; cardiac comorbidity, n=3, patient declined, n=5). 1 consented pt did not have PTCL. 15 out of the first 25 pts in Cohort 1 were progression free after 2 years; median follow up of 31 mon (21 - 36 mon). Estimated 2-year PFS was 62% (45-83%, 95% CI); median PFS 30 mon (12.0- NA, 95% CI). In Cohort 2, estimated 2-year PFS was 43% (18 – 100, 95% CI); median follow up of 30 mon (range, 24 – 37 mon); median PFS 14 mon (5 – NA, 95% CI). Across cohorts, 5 pts required dose reduction. The most common toxicities (≥10% of pts, all grades) were fatigue (n=24, 73%), decreased platelets (n=16, 48%) and anemia (n=16, 48%). Conclusions: While the study did not meet its desired primary efficacy endpoint, maintenance romi was well-tolerated with an estimated 2-year PFS of 62%, greater than historical data. A larger, randomized study would be needed to determine the superiority of this approach. Clinical trial information: NCT01908777. [Table: see text]

Impact of duration of prior cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy on alpelisib (ALP) benefit in patients (pts) with hormone receptor–positive (HR+), human epidermal growth factor receptor-2–negative (HER2–), PIK3CA-mutated advanced breast cancer (ABC) from BYLieve

1060

Background: Mutations in PIK3CA (encoding PI3Kα) are present in ̃40% of HR+, HER2– ABC tumors and are associated with relative endocrine resistance and poor prognosis. ALP inhibits and degrades PI3Kα. Primary analyses of Cohorts A and B from the phase 2 BYLieve study demonstrated that ALP + endocrine therapy (ET; fulvestrant [FUL] or letrozole [LET]) is effective and safe in pts with HR+, HER2– PIK3CA-mutated ABC with prior CDK4/6i therapy. Here, we evaluate if duration of prior CDK4/6i-based therapy impacts benefit of ALP + ET in these 2 cohorts. Methods: Cohorts A and B of BYLieve included pre/postmenopausal women who received CDK4/6i + AI or FUL, respectively, as immediate prior therapy. Cohort A received ALP 300 mg PO QD + FUL 500 mg IM Q28D + C1D15; Cohort B received ALP 300 mg PO QD + LET 2.5 mg PO QD. Within each cohort, pts were divided into 2 subgroups per duration of prior CDK4/6i therapy (“high”/”low,” above/below median duration of therapy) and the association of progression-free survival (PFS) with this covariate was analyzed using stratified log-rank test and Cox PH model. This analysis included pts for whom duration of prior CDK4/6i therapy was known, and efficacy was assessed in pts with centrally confirmed PIK3CA mutation in tumor tissue. Results: Of the 126 pts in Cohort A with duration of prior CDK4/6i available, 120 had centrally confirmed PIK3CA-mutated disease; 60 were exposed to CDK4/6i for > 380 days (high) and 60 for < 380 days (low), with similar demographics/disease characteristics between subgroups. There was no significant difference in PFS between the high vs low subgroups (HR 1.03; 95% CI, 0.64-1.64; P= 0.927; median 8.0 vs 7.0 mo). Grade ≥3 adverse events (AEs) were experienced by 66.9% (n = 85) of all pts in Cohort A and 66.7% (n = 42)/68.3% (n = 43) in the high/low subgroups, respectively. Of the 123 pts in Cohort B with duration of prior CDK4/6i available, 113 had centrally confirmed PIK3CA-mutated disease; 57 were exposed to CDK4/6i for > 305 days (high) and 56 for < 305 days (low), with similar demographics/disease characteristics between subgroups. There was no significant difference in PFS between high vs low subgroups (HR 1.20; 95% CI, 0.78-1.84; P= 0.400; median 5.4 vs 5.9 mo). Grade ≥3 AEs were experienced by 69.8% (n = 88) of all pts in Cohort B and 71.0% (n = 44)/68.9% (n = 42) in the high/low subgroups, respectively. Conclusions: This analysis demonstrates that the benefit and safety profiles of ALP + ET are similar in pts with HR+, HER2– PIK3CA-mutated ABC who achieved relatively shorter duration of disease control with prior CDK4/6i vs those with longer duration of disease control, and suggests that ALP overcomes acquired resistance to CDK4/6i in these pts. Clinical trial information: NCT03056755 .

Brentuximab Vedotin Combined With Chemotherapy in Patients With Newly Diagnosed Early-Stage, Unfavorable-Risk Hodgkin Lymphoma

PURPOSE

To improve curability and limit long-term adverse effects for newly diagnosed early-stage (ES), unfavorable-risk Hodgkin lymphoma.

METHODS

In this multicenter study with four sequential cohorts, patients received four cycles of brentuximab vedotin (BV) and doxorubicin, vinblastine, and dacarbazine (AVD). If positron emission tomography (PET)-4-negative, patients received 30-Gy involved-site radiotherapy in cohort 1, 20-Gy involved-site radiotherapy in cohort 2, 30-Gy consolidation-volume radiotherapy in cohort 3, and no radiotherapy in cohort 4. Eligible patients had ES, unfavorable-risk disease. Bulk disease defined by Memorial Sloan Kettering criteria (> 7 cm in maximal transverse or coronal diameter on computed tomography) was not required for cohorts 1 and 2 but was for cohorts 3 and 4. The primary end point was to evaluate safety for cohort 1 and to evaluate complete response rate by PET for cohorts 2-4.

RESULTS

Of the 117 patients enrolled, 116 completed chemotherapy, with the median age of 32 years: 50% men, 98% stage II, 86% Memorial Sloan Kettering-defined disease bulk, 27% traditional bulk (> 10 cm), 52% elevated erythrocyte sedimentation rate, 21% extranodal involvement, and 56% > 2 involved lymph node sites. The complete response rate in cohorts 1-4 was 93%, 100%, 93%, and 97%, respectively. With median follow-up of 3.8 years (5.9, 4.5, 2.5, and 2.2 years for cohorts 1-4), the overall 2-year progression-free and overall survival were 94% and 99%, respectively. In cohorts 1-4, the 2-year progression-free survival was 93%, 97%, 90%, and 97%, respectively. Adverse events included neutropenia (44%), febrile neutropenia (8%), and peripheral neuropathy (54%), which was largely reversible.

CONCLUSION

BV + AVD × four cycles is a highly active and well-tolerated treatment program for ES, unfavorable-risk Hodgkin lymphoma, including bulky disease. The efficacy of BV + AVD supports the safe reduction or elimination of consolidative radiation among PET-4-negative patients.

Alpelisib plus fulvestrant in PIK3CA-mutated, hormone receptor-positive advanced breast cancer after a CDK4/6 inhibitor (BYLieve): one cohort of a phase 2, multicentre, open-label, non-comparative study

BACKGROUND

Alpelisib, a PI3Kα-selective inhibitor and degrader, plus fulvestrant showed efficacy in hormone receptor-positive, HER2-negative, PIK3CA-mutated advanced breast cancer in SOLAR-1; limited data are available in the post-cyclin-dependent kinase 4/6 inhibitor setting. BYLieve aimed to assess alpelisib plus endocrine therapy in this setting in three cohorts defined by immediate previous treatment; here, we report results from cohort A.

METHODS

This ongoing, phase 2, multicentre, open-label, non-comparative study enrolled patients with hormone receptor-positive, HER2-negative, advanced breast cancer with tumour PIK3CA mutation, following progression on or after previous therapy, including CDK4/6 inhibitors, from 114 study locations (cancer centres, medical centres, university hospitals, and hospitals) in 18 countries worldwide. Participants aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 2 or less, with no more than two previous anticancer treatments and no more than one previous chemotherapy regimen, were enrolled in three cohorts. In cohort A, patients must have had progression on or after a CDK4/6 inhibitor plus an aromatase inhibitor as the immediate previous treatment. Patients received oral alpelisib 300 mg/day (continuously) plus fulvestrant 500 mg intramuscularly on day 1 of each 28-day cycle and on day 15 of cycle 1. The primary endpoint was the proportion of patients alive without disease progression at 6 months per local assessment using Response Evaluation Criteria in Solid Tumors, version 1.1, in patients with a centrally confirmed PIK3CA mutation. This trial is registered with ClinicalTrials.gov, NCT03056755.

FINDINGS

Between Aug 14, 2017, and Dec 17, 2019 (data cutoff), 127 patients with at least 6 months' follow-up were enrolled into cohort A. 121 patients had a centrally confirmed PIK3CA mutation. At data cutoff, median follow-up was 11·7 months (IQR 8·5-15·9). 61 (50·4%; 95% CI 41·2-59·6) of 121 patients were alive without disease progression at 6 months. The most frequent grade 3 or worse adverse events were hyperglycaemia (36 [28%] of 127 patients), rash (12 [9%]), and rash maculopapular (12 [9%]). Serious adverse events occurred in 33 (26%) of 127 patients. No treatment-related deaths were reported.

INTERPRETATION

BYLieve showed activity of alpelisib plus fulvestrant with manageable toxicity in patients with PIK3CA-mutated, hormone receptor-positive, HER2-negative advanced breast cancer, after progression on a CDK4/6 inhibitor plus an aromatase inhibitor.

FUNDING

Novartis Pharmaceuticals.

Abstract PD2-07: Alpelisib + letrozole in patients with PIK3CA-mutated, hormone-receptor positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) advanced breast cancer (ABC) previously treated with a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) + fulvestrant: BYLieve study results

Introduction: Mutations in PIK3CA, which encodes the α-isoform of phosphatidylinositol 3-kinase (PI3Kα), occur in ~40% of patients (pts) with HR+, HER2- ABC and can contribute to endocrine resistance. Alpelisib (ALP), a PI3Kα-selective inhibitor and degrader, plus fulvestrant (FUL) demonstrated efficacy in the phase 3 SOLAR-1 trial, which included 20 pts who had prior CDK4/6i in the PIK3CA-mutant cohort. Limited clinical data are available in the post-CDK4/6i setting for PIK3CA-mutated, HR+, HER2- ABC. BYLieve (NCT03056755), an ongoing phase 2, multicenter, open-label, 3-cohort noncomparative study, is the first trial evaluating ALP + endocrine therapy (FUL or letrozole [LET]) in pts with PIK3CA-mutated, HR+, HER2- ABC who progressed on/after prior therapy, including CDK4/6i. In the prior CDK4/6i + aromatase inhibitor (AI) cohort (Cohort A), pts received ALP + FUL. With median follow-up of 11.7 months (mo), the primary endpoint in Cohort A was met—50.4% of pts were alive and without disease progression (PD) at 6 mo per local investigator assessment (n=61; 95% CI, 41.2%-59.6%). Median progression-free survival (mPFS) was 7.3 mo (n=72; 95% CI, 5.6-8.3 mo); AEs were consistent with prior observations. Now, we report on the cohort of pts who received a CDK4/6i + FUL as immediate prior therapy before enrollment (Cohort B). Methods: Daily oral treatment in Cohort B consisted of ALP 300 mg + LET 2.5 mg. Each cohort planned to enroll at least 112 pts with centrally confirmed PIK3CA mutation, based on immediate prior treatment of either a CDK4/6i + AI (Cohort A), a CDK4/6i + FUL (Cohort B), or systemic chemotherapy or endocrine therapy (which may also include prior CDK4/6i + FUL; Cohort C, follow-up ongoing). The primary endpoint, the proportion of pts with centrally confirmed PIK3CA mutation alive without PD at 6 mo per local investigator using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, is assessed for each cohort separately and is met if the lower bound of the 95% CI is &gt;30%. Men and premenopausal women were allowed goserelin 3.6 mg subcutaneously or leuprolide 7.5 mg intramuscularly every 28 days. Results: 126 pts whose immediate prior treatment was CDK4/6i + FUL were enrolled into Cohort B: 115 had centrally confirmed PIK3CA mutations. Median follow-up was 15.0 mo (range, 1-31 mo); 58 (46.0%) had ≥2 lines of prior therapy in the metastatic setting, and 103 (81.7%) pts progressed on prior AI therapy. The primary endpoint was met with 46.1% (95% CI, 36.8%-55.6%) of pts alive without PD at 6 mo. mPFS was 5.7 mo (95% CI, 4.5-7.2 mo). The most frequent all-grade AEs (≥25%) were diarrhea (67.5%), hyperglycemia (63.5%), nausea (54.8%), decreased appetite (44.4%), stomatitis (34.1%), fatigue (31.0%), rash (31.0%), and vomiting (24.6%). Most frequent grade ≥3 AEs included hyperglycemia (25.4%), rash (9.5%), and rash maculopapular (7.9%). Incidence of AEs leading to treatment discontinuation was 14.3% (n=18); most frequent AEs leading to discontinuation were rash (4 pts, 3.2%, including rash maculopapular), fatigue, and diarrhea (3 pts, 2.4% each). Conclusion: Alpelisib in combination with LET following progression on FUL + CDK4/6i and prior AIs was effective in this noncomparative trial. Consistent with the known safety profile of alpelisib, manageable toxicities were observed. These data suggest that alpelisib in combination with LET may be an effective treatment option for pts with PIK3CA-mutated, HR+, HER2- ABC in the post-CDK4/6i setting.

Citation Format: Hope S. Rugo, Florence Lerebours, Dejan Juric, Nicholas Turner, Stephen Chia, Pamela Drullinsky, Aleix Prat, Rafael Villanueva Vázquez, Murat Akdere, Christina Arce, Yu-Ming Shen, Eva Ciruelos. Alpelisib + letrozole in patients with PIK3CA-mutated, hormone-receptor positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) advanced breast cancer (ABC) previously treated with a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) + fulvestrant: BYLieve study results [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD2-07.

Alpelisib (ALP) + fulvestrant (FUL) in patients (pts) with PIK3CA-mutated (mut) hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (ABC) previously treated with cyclin-dependent kinase 4/6 inhibitor (CDKi) + aromatase inhibitor (AI): BYLieve study results

1006

Background: PIK3CA mutations (mut) occur in ~40% of pts with HR+, HER2– ABC and are associated with poor prognosis and resistance to treatment (tx). ALP, a PI3Kα inhibitor, plus FUL demonstrated efficacy in the phase 3 SOLAR-1 trial of HR+, HER2– PIK3CA-mut ABC. Little clinical data and few prospective studies are available to inform tx decisions for pts with HR+, HER2– PIK3CA-mut ABC in the post-CDKi setting. BYLieve is the first trial evaluating ALP + endocrine therapy (ET; FUL or letrozole) in pts with HR+, HER2– PIK3CA-mut ABC who progressed on/after prior therapy, including CDKi. In this ongoing phase 2, open-label, noncomparative study, 112 pts with centrally confirmed PIK3CA mut in tumor tissue are enrolled in each cohort per immediate prior tx of CDKi + AI, CDKi + FUL, or systemic chemo or ET. Enrollment is complete in prior CDKi + AI and CDKi + FUL cohorts and ongoing in prior systemic chemo or ET cohort. We report on the cohort of pts with CDKi + AI as immediate prior tx. Methods: Pts received ALP 300 mg/day + FUL 500 mg Q28D + C1D15. Primary endpoint was proportion of pts alive without disease progression at 6 mo per local assessment; 2-sided 95% confidence intervals (CI) were calculated using Clopper and Pearson (1934) exact method. Evidence of clinically meaningful tx effect was defined as the lower bound of the 95% CI > 30%. Safety was assessed in all patients; AEs presented by preferred term. Results: 127 pts whose immediate prior tx was CDKi + AI were enrolled, of whom 121 had centrally confirmed PIK3CA mut; median follow-up was 11.7 mo. Primary endpoint was met: proportion of pts without disease progression at 6 mo was 50.4% (95% CI, 41.2-59.6). Most frequent all-grade AEs were diarrhea (60%), hyperglycemia (58%), nausea (46%), fatigue (29%), decreased appetite (28%), and rash (28%). Most frequent grade ≥3 AEs included hyperglycemia (28%), rash (9%), and rash maculopapular (9%). Incidence of AEs leading to discontinuation was low; most frequent AEs leading to discontinuation were rash (5 pts, 3.9%), colitis, hyperglycemia, urticaria, and vomiting (2 pts, 1.6% each). Conclusions: With follow-up still ongoing, BYLieve shows in a large number of pts that ALP + FUL demonstrates clinically meaningful efficacy and manageable toxicity post CDKi tx. Building on findings from SOLAR-1, BYLieve further supports use of ALP + FUL for HR+, HER2– PIK3CA-mut ABC. Clinical trial information: NCT03056755 .

Prevalence and characterization of dermatologic adverse events related to alpelisib (BYL719) in breast cancer patients

1063

Background: Rash develops in approximately 50% of breast cancer patients receiving alpelisib, often requiring dose modifications. Herein, we describe the characteristics of alpelisib-related dermatologic adverse events (dAEs). Methods: A single center retrospective analysis was conducted via review of electronic medical records. We collected clinical, laboratory and management data relevant to patients treated with alpelisib for advanced breast cancer under four different randomized clinical trials or post approval by regulatory agencies from 6/1/2013 to 7/31/2019. Type and severity of dAEs was recorded using the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v5.0). Results: A total of 102 patients (mean age 56 years, range 27-83) receiving alpelisib from 200 to 350 mg daily, most frequently in combination with endocrine therapy (79, 77.5%) were included. We identified 41 (40.2%) patients with all-grade rash [CTCAE grade 1/2 = 22 (21.6%); CTCAE grade 3 = 19, (18.6%)] distributed primarily along the trunk (18, 78%) and developing, on average, within 12.8 +/- 1.5 days of treatment initiation (n = 38). Mean duration of rash was 7.1 +/- 3.8 days; and no grade 4 dAEs were observed. Of 29 patients with documented morphology of alpelisib-related dAEs, the majority (26, 89.7%) had maculopapular rash. Thirteen (68%) of 19 patients with any-grade rash and report of any associated symptoms had pruritus (7, 36%) or burning pain (6, 32%). All-grade dAEs correlated with an increase in serum eosinophils from 2.7% to 4.4% (p < 0.05), and prophylaxis with non-sedating antihistamines (n = 43) was correlated with a reduction of grade 1/2 rash onset (OR 0.39, p = 0.09). Sixteen (84.2%) of 19 patients with grade 3 dAEs had interruption of alpelisib, followed by management with antihistamines, topical and/or systemic corticosteroids. We did not observe rash recurrence in 12 (75%) of these 16 patients who re-initiated therapy; and the majority (9, 56.3%) were re-challenged without a dose reduction. Conclusions: Pruritus and increased blood eosinophils occur with maculopapular rash within the first two weeks of initiating alpelisib and persists for approximately seven days. To reduce onset of grade 1/2 rash, non-sedating antihistamines (i.e. cetirizine) are recommended during the first eight weeks. While grade 3 rash leads to interruption of alpelisib, dermatologic improvement is evident with systemic corticosteroids; and most patients can resume therapy at a maintained or reduced dose upon re-challenge.

Alpelisib (ALP) + endocrine therapy (ET) in patients (pts) with PIK3CA-mutated hormone receptor-positive (HR+), human epidermal growth factor-2-negative (HER2-) advanced breast cancer (ABC): First interim BYLieve study results

1040

Background: In the phase 3 SOLAR-1 study, ALP + fulvestrant (FUL) improved PFS in pts with HR+, HER2– ABC with a PIK3CA mutation overall and in the small group of pts with prior cyclin-dependent kinase 4/6 inhibitor (CDKi) use. We report interim data from the BYLieve study in pts with PIK3CA-mutated ABC and prior CDKi exposure. Methods: BYLieve is an ongoing, phase 2, open-label, non-comparative study of ALP 300 mg QD + ET in men and women with PIK3CA-mutated HR+, HER2– ABC whose disease progressed on/after CDKi + ET. Pts are permitted ≤2 prior anticancer therapies and ≤1 prior chemotherapy regimen for ABC. Pts with prior CDKi and AI ( FUL cohort) receive ALP and FUL 500 mg Q28d + C1d15 IM. Pts with prior CDKi and FUL ( LET cohort) receive ALP and letrozole (LET) 2.5 mg PO QD. In this preplanned interim analysis, conducted after ≥20 pts in FUL had ≥6 mo of follow-up, descriptive data are reported for preliminary safety and efficacy in the FUL and LET cohorts. Results: At data cutoff, 64 and 36 pts were enrolled in the FUL and LET cohorts, respectively; 39 pts ( FUL, n = 21; LET, n = 18) have safety and efficacy data with ≥6 mo follow-up and are reported here. Data on 100 pts enrolled at the time of data cutoff will be presented. In the 39 pts with ≥6 mo follow-up, median ALP duration was 5.3 and 5.5 mo in FUL and LET, respectively; median duration of FUL and LET was 5.6 mo. Median relative ALP dose intensity was 93% ( FUL) and 87% ( LET). Most common grade ≥3 adverse events were hyperglycemia (38.1% ( FUL) and 27.8% ( LET)) and rash (4.8% ( FUL) and 27.8% ( LET)). Only 2 pts (5%; 1 pt per cohort) discontinued due to an AE. In pts with centrally confirmed PIK3CA mutation (n = 20 ( FUL); n = 17 ( LET)), ORR was 20% ( FUL) and 18% ( LET), CBR was 40% ( FUL) and 35% ( LET). Efficacy and safety data for the 100 enrolled pts will be presented at the meeting. Conclusions: Pending further readout of the ongoing BYLieve trial, safety and tolerability of ALP and hormonal therapy in pts with prior CDKi are consistent with those of SOLAR-1; discontinuation due to toxicity was rare. NCT03056755. Clinical trial information: NCT02437318.

Phase III study of taselisib (GDC-0032) + fulvestrant (FULV) v FULV in patients (pts) with estrogen receptor (ER)-positive, PIK3CA-mutant (MUT), locally advanced or metastatic breast cancer (MBC): Primary analysis from SANDPIPER

LBA1006

Background: Taselisib, a potent, selective PI3K inhibitor, has enhanced activity in PIK3CA-MUT BC cell lines and confirmed partial responses in PIK3CA-MUT BC as a single-agent or with FULV. We assessed taselisib + FULV in pts with ER-positive, HER2-negative, PIK3CA-MUT locally advanced or MBC. Methods: SANDPIPER (NCT02340221) is a double-blind, placebo (PBO)-controlled, randomized, phase III study. Postmenopausal pts with disease recurrence or progression during or after an aromatase inhibitor were randomized 2:1 to receive taselisib (4 mg oral, qd) or PBO + FULV (500 mg). Stratification factors were: visceral disease, endocrine sensitivity, and geographic region. Pts with PIK3CA-MUT tumors, assessed by central cobas PIK3CA Mutation Test, were randomized separately from non-MUT tumors. The primary endpoint was investigator-assessed progression-free survival (INV-PFS) in pts with PIK3CA-MUT tumors. Secondary endpoints included objective response rate (ORR), overall survival (OS), clinical benefit rate (CBR), duration of objective response (DoR), PFS by blinded independent central review (BICR-PFS), and safety. Results: 516 pts were randomized in the PIK3CA-MUT intention-to-treat (ITT) population. Efficacy is shown in the Table. Taselisib + FULV significantly improved INV-PFS (hazard ratio [HR] 0.70) as confirmed by BICR-PFS (HR 0.66). OS is immature. The most common grade ≥3 adverse events (AEs; preferred terms) in the taselisib + FULV arm in safety-evaluable pts who received ≥ 1 dose of treatment were diarrhea (12%), hyperglycemia (10%), colitis (3%), and stomatitis (2%). AEs led to more taselisib discontinuations (17% v 2%) and dose reductions (37% v 2%), v PBO. Conclusions: Taselisib + FULV significantly improved INV-PFS, v PBO + FULV, in pts with ER-positive, HER2-negative, PIK3CA-MUT locally advanced or MBC. The safety profile is largely consistent with previous studies. Clinical trial information: NCT02340221. [Table: see text]

Phase I dose escalation of ibrutinib and buparlisib in relapsed/refractory diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma (MCL), and follicular lymphoma (FL)

7544

Background: In vitro studies of BTK and PI3K inhibitors demonstrate synergy in non-Hodgkin lymphoma (NHL). We embarked on a phase I/Ib investigator-initiated clinical trial evaluating the combination of ibrutinib (BTK inhibitor) and buparlisib (pan-PI3K inhibitor) in relapsed/refractory (R/R) NHL. The completed dose escalation is reported. Methods: Patients (pts) were eligible if they had R/R DLBCL, MCL, or FL with ECOG≤2 and adequate organ function. Ibrutinib and buparlisib were given daily by mouth on a 28-day cycle. Dose reductions were permitted after cycle 1. Tumor response was based on Lugano Classification however CR required both PET resolution and ≥ PR by CT. Results: As of Dec 16, 2016, 13 pts were enrolled and evaluated for toxicity (DLBCL 5, FL 2, MCL 6). Dose levels and DLT per table. Six pts discontinued treatment for disease progression (DLBCL 4, FL 2). Hematologic AE ≥ grade 3 are anemia (2), leukocytosis (2), and leukopenia (4). Relevant non-hematologic AEs of any grade ≥ 20% across all pts were fatigue (77%), diarrhea (62%), anorexia (54%), rash (46%), hyperbilirubinemia (46%), gastric reflux (46%), CMV reactivation (31%), mood change (31%), and hypertension (23%). Most common related grade 3/4 toxicity is rash (N = 3). No grade 5 toxicities noted. Serious adverse events (SAE) include: grade 2 pleural effusion and grade 2 nausea (N = 1), grade 1 fever with hospitalization (N = 1), grade 2 confusion and grade 4 hyponatremia (N = 1) were unrelated to therapy. Responses noted in 13 pts: MCL (N = 6: CR 4, PR 2), FL (N = 2: SD 2), DLBCL (N = 5: SD 1). One CR was a MCL pt with CR after 2 cycles on combination therapy and continues in remission on ibrutinib alone because of buparlisib toxicity. Conclusions: Combination of ibrutinib and buparlisib while generally well tolerated has predicted toxicities of both BTK and PI3K inhibitors. The recommended phase 2 dose is ibrutinib 560 mg and buparlisib 100 mg though dose reductions for tolerability may be needed for long term oral therapies. Promising efficacy is observed in MCL. Clinical trial information: NCT02756247. [Table: see text]

A phase II open-label study of ganetespib, a novel heat shock protein 90 inhibitor for patients with metastatic breast cancer

BACKGROUND

Ganetespib is a small molecule, nongeldanamycin HSP90 inhibitor with potent inhibitory effects on HSP90-dependent oncoproteins of relevance to breast cancer pathogenesis. We therefore tested ganetespib in an unselected cohort of patients with MBC.

PATIENTS AND METHODS

Patients were treated with single agent ganetespib at 200 mg/m(2) once weekly for 3 weeks, on a 28-day cycle. Therapy was continued until disease progression. The primary end point was ORR using Reponse Evaluation Criteria in Solid Tumors version 1.1.

RESULTS

Twenty-two patients were enrolled with a median age of 51(range, 38-70) years and a median Eastern Cooperative Oncology Group performance status of 0 (range, 0-1). Most patients had at least 2 previous lines of chemotherapy in the metastatic setting. Most common toxicities, largely grade 1/2, were diarrhea, fatigue, nausea, and hypersensitivity reaction. The ORR in this unselected population was 9%, with all responses coming from the subset of patients with HER2-positive MBC (2/13; 15%). One patient with TNBC had objective tumor regression in the lung metastases. The clinical benefit rate (complete response + partial response + stable disease > 6 months) was 9%, median progression-free survival was 7 weeks (95% confidence interval [CI], 7-19), and median overall survival was 46 weeks (95% CI, 27-not applicable).

CONCLUSION

The study did not meet the prespecified criteria for ORR in the first stage of the Simon 2-stage model in this heavily pretreated unselected population of MBC. However, activity was observed in trastuzumab-refractory HER2-positive and TNBC. Ganetespib was well tolerated and responses in more targeted populations harboring specific HSP90-dependent oncoproteins justifies its further study, particularly as part of rational combinations.

Phase II study of pertuzumab, trastuzumab, and weekly paclitaxel in patients with HER2-overexpressing metastatic breast cancer (MBC)

134

Background: Pertuzumab (P) is a monoclonal antibody which binds to extracellular domain II of HER2 distally from trastuzumab (H), disrupting HER2 dimerization and signaling. The CLEOPATRA phase III trial showed that HP + docetaxel in HER2+ MBC prolonged progression-free survival (PFS) compared to placebo + H + docetaxel. We report preliminary results of a phase II study to evaluate the safety and efficacy of weekly paclitaxel (T) with HP (THP). Methods: Patients (pts) with HER2+ MBC with 0-1 prior treatment (Rx) are eligible. Pts receive weekly (w) paclitaxel (80mg/m2), q3w trastuzumab (loading dose 8mg/kg → 6mg/kg), and q3w pertuzumab (flat loading dose 840mg → flat dose 420mg). The primary endpoint is PFS at 6 months (mo). Secondary endpoints include response, safety (including cardiac events), and tolerability. Evaluable pts are those who have started study Rx and are assessed at 6 mo for PFS. Left ventricular ejection fraction (LVEF) is monitored by echocardiogram every 3 mo. Cardiac events are defined as symptomatic LV systolic dysfunction (LVSD), non-LVSD cardiac death, or probable cardiac death. Results: As of 5-1-12, 33 of the planned 69 pts were enrolled; 16 were evaluable at 6 mo. Of the 16 pts, G 3/4 toxicities included sepsis (1pt, 6%), cholecystitis (1pt, 6%), fatigue (1pt, 6%), skin ulceration (1pt, 6%) and cystic macular degeneration (1 pt with prior prolonged Rx with paclitaxel, 6%). G 1/2 toxicities included alopecia (16 pts, 100%), fatigue (15 pts, 94%), ALT/AST elevation (14 pts, 88%), neuropathy (14 pts, 88%), diarrhea (12 pts, 75%), rash (9 pts, 56%), nail changes (8 pts, 50%), nausea (7 pts, 44%), mucositis (7 pts, 44%), and dry skin (6 pts, 38%). Median LVEF was 63% at baseline, 60% at 3 mo and 58% at 6 mo. There were no cardiac events. At 6 mo, 12/16 pts (75%) were progression-free (2 CR, 7 PR and 3 SD); 4 pts progressed. Conclusions: Our single-center phase II study continues to accrue, with no significant diarrhea or signal of increased cardiac toxicity to date. If the estimate of activity is similar to results with docetaxel in CLEOPATRA, this will provide support for THP as an alternative option in this setting.

Final results of phase I/II trial of vorinostat in combination with cyclophosphamide, etoposide, prednisone, and rituximab (R-CVEP) for elderly patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL)

8054

Background: Standard treatment of relapsed/refractory DLBCL in elderly patients who are not candidates for autologous stem cell transplantation (auSCT) has not been established. Cyclophosphamide (C), etoposide (E), prednisone (P) and procarbazine (CEPP) has been used by many clinicians based on limited data (Blood 76: 1293-98, 1990). Vorinostat (V) is a histone deacetylase inhibitor that is approved for relapsed cutaneous T-cell lymphoma and has activity in B-cell lymphomas. This trial defined the maximum tolerated dose (MTD) of V added to standard therapy and determined the response rate of this combination. Methods: Patients ≥age 60 with relapsed/refractory DLBCL not candidates for auSCT were enrolled on R-CVEP (R 375mg/m2 IV, d1; C 600mg/m2 d1 and 8, E 70mg/m2 IV d1, 140mg/m2 d2 and 3; V PO and Pred 60mg/m2 PO d1-10) every 28 days for 6 cycles. In the phase I component V was administered at doses of 300mg/d or 400mg/d for 10 days. The phase I was a 3 + 3 design and the phase II a two stage design requiring 8/20 complete responses (CR) for expansion. Assessment of response utilized end-of-treatment positron emission tomography (PET) (JCO 25: 579-86, 2007). Quality of life (QOL) was measured with the FACT-Lym v.4. Results: 27 pts. were enrolled. 1 died before treatment. For 26 pts: median age 76 yrs. (69-88), 14 females and 12 males, baseline PS (ECOG) 1 (0-2). Median follow-up for survivors: 9.2 mo. Phase I: 6 pts. at 300mg/d (no dose-limiting toxicity-DLT), 6 pts. at 400mg/d (2 grade 3 neutropenia = DLT). MTD 300mg/d x 10d. For 20 pts. at V 300mg/m2 (6 phase I + 14 phase II): 2 off study for toxicity, 1 withdrew consent, 6 CR (30%), 5 partial response (PR) (25%), 6 progressed (30%). Phenotypic overall responses (OR): germinal center (GC) 4/8 (2 CR), non-GC 6/10 (3 CR), transformed CLL 1/2 (1 CR). Median progression-free survival: 10 mo. QOL results will be presented. Conclusions: OR rate for V added to conventional chemotherapy and R was 55% (CR 30%, PR 25%) in relapsed/refractory DLBCL in elderly pts. not candidates for auSCT. This could provide a baseline for comparison with future clinical trials in this understudied population.

Phase II trial of a novel capecitabine dosing schedule in combination with lapatinib for the treatment of patients with HER2-positive metastatic breast cancer

Our group applied mathematical modeling to capecitabine dosing and predicted 7 days of treatment followed by 7 days of rest (7-7) would improve efficacy and minimize toxicity. The conventional schedule of capecitabine limits full dosing in combination with other agents due to toxicity. Lapatinib inhibits the tyrosine kinase of HER2 and has activity when added to conventionally scheduled capecitabine for the treatment of patients with trastuzumab-refractory, HER2-positive, metastatic breast cancer (MBC). We performed this study to evaluate the activity and tolerability of capecitabine 7-7 with lapatinib in patients with trastuzumab-refractory MBC. Eligible patients had measurable, HER2-positive, MBC that progressed following exposure to trastuzumab. Treatment consisted of capecitabine 2,000 mg orally twice daily, 7-7 and lapatinib 1,250 mg orally daily. The primary endpoint was response rate. Secondary endpoints included toxicity, progression-free survival, and stable disease ≥ 6 months. Twenty-three patients were treated on study. More than 60% had prior chemotherapy for MBC and all had prior trastuzumab. After a median of 23 weeks (range 2-96+), five patients had partial responses (23; 95 CI, 7-44%) and six (27; 95 CI, 10-48%) had stable disease ≥ 6 months. Median progression-free survival was 9.4 months. The most common treatment-related toxicities ≥ grade (gr) 2 were hand-foot syndrome (gr 2 43%; gr 3 4% gr 4 0%), diarrhea (gr 2 26%; gr 3/4 0%), elevated liver chemistries (gr 2 17%; gr 3/4 0%), and anemia (gr 2 13%; gr 3 4%; gr 4 4%). No grade ≥ 3 nausea, vomiting, or diarrhea events occurred. This study demonstrated feasibility and after meeting biostatistical requirements for continued accrual was terminated in anticipation of slow enrollment. Capecitabine 7-7 with lapatinib was well tolerated with minimal gastrointestinal toxicity. Antitumor activity was observed in patients with trastuzumab-refractory MBC.

Dose dense cyclophosphamide, methotrexate, fluorouracil is feasible at 14-day intervals: a pilot study of every-14-day dosing as adjuvant therapy for breast cancer

PURPOSE

Cyclophosphamide/methotrexate/fluorouracil (CMF) is a proven adjuvant option for patients with early-stage breast cancer. Randomized trials with other regimens demonstrate that dose-dense (DD) scheduling can offer greater efficacy. We investigated the feasibility of administering CMF using a DD schedule.

PATIENTS AND METHODS

Thirty-eight patients with early-stage breast cancer were accrued from March 2008 through June 2008. They were treated every 14 days with C 600, M 40, F 600 (all mg/m2) with PEG-filgrastim (Neulasta®) support on day 2 of each cycle. The primary endpoint was tolerability using a Simon's 2-stage optimal design. The design would effectively discriminate between true tolerability (as protocol-defined) rates of ≤ 60% and ≥ 80%.

RESULTS

The median age was 52-years-old (range, 38-78 years of age). Twenty-nine of the 38 patients completed 8 cycles of CMF at 14-day intervals.

CONCLUSION

Dose-dense adjuvant CMF is tolerable and feasible at 14-day intervals with PEG-filgrastim support.

Bone Mineral Density (BMD) Changes at 1 Year in Postmenopausal Women Who Are Not Receiving Adjuvant Endocrine Therapy for Breast Cancer (BCA)

Background: Adjuvant therapy for breast cancer (BCA) may be associated with an increased risk for osteoporosis. This prospective, observational study evaluates BMD changes in postmenopausal women undergoing adjuvant chemotherapy (CTX) for early stage BCA, in the absence of endocrine therapy.Methods: Women who have been postmenopausal for at least 5 years, and who were recently diagnosed with Stage 0-III BCA were eligible to undergo serial BMD if adjuvant endocrine therapy was not recommended. Study BMDs were performed at baseline, 1 and 2 years. All patients (pts) were counseled on calcium, vitamin D and weight bearing exercise. This study was designed to assess serial changes in BMD in the individual and to compare changes in those treated with CTX to those who received no systemic therapy (observation). The study was closed prior to reaching target sample size due to slow accrual.Results: Sixteen pts enrolled. Eleven pts received CTX with a dose dense anthracycline and taxane containing regimen and 5 pts received no systemic adjuvant therapy. Twelve pts, median age 63 (range 52-80), have completed the 1 year assessment and are reported here. Two pts treated with CTX and 1 pt on observation were on bisphosphonates at study entry. Baseline BMD mean in gm/cm2 at the lumbar spine (LS) was 1.112 (range 0.807-1.389) and total hip (TH) was 0.989 (range 0.760-1.213). At 1 year, mean BMD at LS was 1.078 (range 0.767-1.347) and TH was 0.956 (range 0.753-1.210). For all 12 pts at 1 year, the individual BMD changes in LS & TH BMD ranged from 10% loss to 2% gain, with 8 of the 9 CTX treated pts losing 1-10% of BMD and the 3 pts on observation staying within 2% of baseline. The mean dosage of dexamethasone used during CTX by the 9 CTX pts was 230 mg (range 156-288mg). The 3 observation pts had no exposure to steroids during the parallel time period.Conclusions: This prospective, observational study supports the hypothesis that adjuvant CTX, and/or its supportive medications, may be associated with acute changes in BMD in postmenopausal women. Patient follow up continues.Funded by Susan G. Komen for the Cure POP0402593

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1066.

Dose-dense (DD) cyclophosphamide, methotrexate, and fluorouracil (CMF) at 14-day intervals: A pilot study of every 14- and 10–11-day dosing intervals for women with early-stage breast cancer

590

Background: CMF (C 600 mg/m2, M 40 mg/m2, F 600 mg/m2) is an option for adjuvant therapy for patients with low risk early stage breast cancer. DD regimens as predicted by mathematical models of cancer growth and treatment response are superior. We previously demonstrated the safety of DD EC (epirubicin/cyclophosphamide) followed by paclitaxel at 10–11 day (d) intervals. We investigated the feasibility of administering DD adjuvant CMF every 14 d and then every 10–11 d in a 2-stage phase II trial. Methods: An initial cohort (A) was treated q 14 d with PEG-filgrastim (Neulasta) support. A second cohort (B) was treated every 10–11 d with filgrastim/Neupogen x 5 d and then, based on feasibility, modified (cohort C) to use 7 d filgrastim. The primary end point was feasibility defined as having ANC > 1.5 x 103/uL on day 1 of planned treatment for all 8 cycles with no grade 3 or higher non-hematologic toxicity. All three cohorts were tested using a Simon's two-stage optimal design with type I and type II errors set at 10%. This design would effectively discriminate between true tolerability (as protocol-defined) rates of< 60% and> 80%. Cohort A: 38 pts with early stage breast cancer were accrued from 3/2008 though 6/2008. Cohort B: 7 pts were accrued from June 2008 through August 2008. Cohort C: Is still open with 16 pts accrued from August 2008 through December 5, 2008. Results: Median age 51: range 38 to 78. Cohort A: 29/38 pts completed 8 cycles of CMF. The regimen was considered feasible. 2 other pts completed 7 cycles and were withdrawn for depression and grade 2 transaminitis. The 7 other pts completed between 1 and 6 cycles of CMF were withdrawn as follows: 3 personal, 1 (grade 3) bone pain, 2 allergy unrelated to CMF, and 1 seizure. Cohort B: 7 pts were accrued. 6 out of 7 pts could not complete 8 cycles of chemotherapy secondary to neutropenia and 1 secondary to grade 3 ALT elevation. Cohort C: Accrual has not been completed. 16 pts are currently enrolled. Conclusions: Dose dense adjuvant CMF is feasible at 14 d intervals with PEG-filgrastim support. Adjuvant CMF every 10–11 days with filgrastim given for 5 days beginning day 2 is not feasible. Accrual is ongoing for CMF at 10–11 days with filgrastim x 7 days. Updated results will be available for Cohort C.

[Table: see text]

Dose-dense (DD) doxorubicin and cyclophosphamide (AC) followed by weekly paclitaxel (P) with trastuzumab (T) and lapatinib (L) in HER2/neu-positive breast cancer is not feasible due to excessive diarrhea: updated results

Abstract #2108

Background: DD q 2 weekly (w) AC → P + T x 1 year (y) has an acceptable safely profile w/ congestive heart failure (CHF) rate of 1/70 pts (Dang, JCO 2008). Lapatinib (L) is effective in HER2 (+) BC. We conducted a pilot study of dd AC → w P + T + L to determine its feasibility and cardiac safety.&#x2028; Methods: Enrolled pts had HER2 (+) BC; LVEF &gt; 50%. Rx consisted of AC at 60/600 mg/m2 x 4 q 2 w (w/ pegfilgrastim 6 mg day 2) → P at 80 mg/m2 x 12 q w + T x 1 y; L (1000 mg daily beginning w/ P + T and continued x 1 y). MUGA is obtained at baseline and at months (mo) 2, 6, 9, and 18. Rx is considered feasible if 1) &gt; 80% pts can complete the PTL phase without a dose delay or reduction and 2) the cardiac event rate (CHF or cardiac death) is &lt; 4%. Pts can remain on-Rx w/ one dose reduction of L (1000 mg → 750 mg) for a G 3 event or &lt; G 3 toxicity (unacceptable).&#x2028; Results: From March 2007 to April 2008, we enrolled 95 pts. Median (med) age was 45 years (range, 28-73). At a med follow-up of 7 months, 90 are evaluable. Of the 90 pts, 34 (37%) withdrew from study during the PTL phase; 29 for a 2nd event of G 3 or unacceptable &lt; G 3 toxicities (15 G 3 diarrhea, 4 G 1/2 diarrhea, 1 G 3 rash, 2 G 2 rash, 1 G 3 dyspnea and also had G 3 diarrhea, 1 G 3 ↑QTc also had G 3 diarrhea, 1 G 3 ↑ALT also had G 3 diarrhea, 1 G 3 paronychia, 1 G 3 pneumonitis, 1 asymptomatic LVEF ↓, 1 myocarditis) and 5 for other reasons (2 personal reason, 1 PCP pneumonia, 1 progression, 1 P hypersensitivity). Overall, 25/90 (27%) pts had G 3 diarrhea and 31/90 (34%) pts required a dose reduction of lapatinib. Med LVEF at baseline is 67% (N=95), at mo 2 is 68% (N=90), at mo 6 is 65% (N=53), and mo 9 is 65% (N=28). To date there are no patient drop-outs due to significant LVEF declines after dd AC; one patient dropped during PTL out due to an asymptomatic LVEF decline.&#x2028; Discussion: L at 1000 mg/day is not feasible combined w/ weekly P and T by protocol stipulation (&gt; 20% pts required L dose reduction) primarily due to excessive G 3 diarrhea. These results have led to the modification of Design 2 (Arm D) of ALTTO. We will report updated results.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2108.

The safety of dose-dense doxorubicin and cyclophosphamide followed by paclitaxel with trastuzumab in HER-2/neu overexpressed/amplified breast cancer

PURPOSE

Dose-dense (dd) doxorubicin and cyclophosphamide (AC) followed by paclitaxel (P) is superior to every 3-weekly AC followed by P. Given the demonstrated cardiac safety for trastuzumab (T) with conventionally scheduled AC followed by P, we tested the safety of dd AC followed by P with T. The primary end point was cardiac safety, and the secondary end points were time to recurrence and overall survival.

METHODS

Patients with HER-2/neu immunohistochemistry (IHC) 3+ or fluorescent in situ hybridization (FISH)-amplified breast cancer and baseline left ventricular ejection fraction (LVEF) of >or= 55% were enrolled, regardless of tumor size or nodal status. Treatment consisted of AC (60/600 mg/m(2)) x 4 followed by P (175 mg/m(2)) x 4 every 2-weekly with pegfilgrastim (6 mg on day 2) + T x1 year. LVEF by radionuclide scan was obtained at baseline, at months 2, 6, 9, and 18.

RESULTS

From January 2005 to November 2005, 70 patients were enrolled. The median age was 49 years (range, 27 to 72 years); median LVEF at baseline was 68% (range, 55% to 81%). At month 2 in 70 of 70 patients, the median LVEF was 67% (range, 58% to 79%); at month 6 in 67 of 70 patients, it was 66% (range, 52% to 75%); at month 9 in 68 of 70 patients, it was 65% (range, 50% to 75%); and at month 18 in 48 of 70 patients, it was 66% (range, 57% to 75%). As of December 1, 2007, the median follow-up was 28 months (range, 25 to 35 months). One patient (1%) experienced congestive heart failure (CHF). There were no cardiac deaths.

CONCLUSION

Dose-dense AC followed by P/T followed by T is feasible and is not likely to increase the incidence of cardiac events compared to established regimens.

Telomerase activity and telomere length in acute and chronic leukemia, pre- and post-ex vivo culture

We studied telomerase regulation and telomere length in hematopoietic progenitor cells from peripheral blood and bone marrow from patients with acute and chronic leukemia and myeloproliferative diseases. CD34+ cells from a total of 93 patients with either acute myeloid leukemia (AML; n = 25), chronic myeloid leukemia (CML; n = 21), chronic lymphocytic leukemia (CLL; n = 18), polycythemia vera (PV; n = 16), or myelodysplastic syndromes (MDS; n = 13) were analyzed before and in 19 patients after ex vivo expansion in the presence of multiple cytokines (kit ligand, interleukin-3, interleukin-6, and granulocyte colony-stimulating factor plus erythropoietin). Compared with hematopoietic progenitor cells from normal donors (n = 108), telomerase activity (TA) was increased 2- to 5-fold in chronic phase (CP)-CML, CLL, PV, and MDS. In AML, accelerated phase (AP) and blastic phase (BP)-CML, basal TA was 10- to 50-fold higher than normal. TA of CP-CML CD34+ cells was up-regulated within 72 h of ex vivo culture, peaked after 1 week, and decreased below detection after 2 weeks. In contrast, TA in AP/BP-CML and AML CD34+ cells was down-regulated after 1 week of culture and decreased further thereafter. The expansion potential of CD34+ cells from patients with leukemia was considerably decreased compared with CD34+ cells from normal donors. The average expansion of cells from leukemic individuals was 6.5-, 2.3-, 0.6-, and 0.2-fold in weeks 1, 2, 3, and 4, respectively, whereas expansion of normal cells was 5- to 15-fold higher. In serial expansion culture, a median telomeric loss of 0.7 kbp was observed during 3-4 weeks of expansion. Our results demonstrate that up-regulation of telomerase is similar in CD34+ cells from CP-CML, CLL, PV, and MDS patients and in normal hematopoietic cells during the first week of culture, whereas in AML and AP/BP-CML, telomerase is high at baseline and down-regulated during expansion culture. High levels of telomerase in leukemic progenitors at baseline may be a feature of both the malignant phenotype and rapid cycling. Telomerase down-regulation during culture of leukemic cells may be due to the decreased expansion potential or repression of normal hematopoiesis, or in AML it may be due to the partial differentiation of AML cells, shown previously to be associated with loss of TA. Telomere shortening during ex vivo expansion correlated with low levels of TA, particularly in chronic leukemic and MDS progenitors where telomerase was insufficient to protect against telomere bp loss during intense proliferation.

A phase I trial of a single high dose of idarubicin combined with high-dose cytarabine as induction therapy in relapsed or refractory adult patients with acute lymphoblastic leukemia

Relapsed or refractory adult acute lymphoblastic leukemia (ALL) carries a grave prognosis. The most promising strategy for curing these patients is through re-induction chemotherapy followed by successful allogeneic transplant. We studied a new high-dose induction regimen in order to improve the outcome for these patients. Eighteen adult patients with relapsed/refractory ALL were treated on a phase I study of high-dose cytarabine combined with a single escalating dose of idarubicin. Five patients had primary refractory disease and 13 were treated in refractory relapse. Nine patients (50%) had Ph+ ALL. The induction regimen was cytarabine 3 g/m2/day intravenously days 1-5 and idarubicin as a single intravenous dose on day 3. G-CSF 5 microg/kg subcutaneously every 12 h was started on day 7. The initial idarubicin dose was 20 mg/m2 with dose escalations of 10 mg m2. Cohorts of three patients were treated at each idarubicin dose level. Unacceptable toxicity was encountered at 50 mg/m2 with one death from infection and one death from cardiotoxicity in a patient with significant prior anthracycline exposure. There were no instances of grade 4 non-hematologic toxicity encountered at idarubicin doses of 20 mg/m2, 30 mg/m2, or 40 mg/m2. The data suggest a dose-response relationship for increasing doses of idarubicin with 0/3 complete responses (CR) at 20 mg/m2, 1/3 CR at 30 mg/m2, and 7/12 (58%) CR at idarubicin doses > or = 40 mg/m2. We conclude that concomitant administration of cytarabine 3 g/m2/day x 5 and high-dose idarubicin at 40 mg/m2 as a single dose on day 3 can be administered safely to patients with refractory and relapsed ALL.

Telomerase activity and telomere length in pediatric patients with malignancies undergoing chemotherapy

Telomerase activity and telomere length in mononuclear cells (MNCs) and granulocytes from peripheral blood (PB) and bone marrow (BM) specimens were studied in pediatric acute leukemia (ALL, n = 15; AML, n = 11) and pediatric solid tumor (ST) patients (n = 9) at diagnosis, during and after chemotherapy. In four ST patients, tumor tissue was also available. For comparative analysis, MNCs from healthy donors (n = 53) were analyzed. Telomerase was evaluated using a modified telomeric repeat amplification protocol (TRAP) assay, and telomere length by terminal restriction fragment (TRF) analysis. At diagnosis, high telomerase activity was detected in MNCs from all leukemia patients, which was similar to the activity from ST biopsy specimens. This exceeded by 10- to 20-fold the activity in PB MNCs from ST patients and healthy donors (P < 0.05). Granulocyte fractions lacked telomerase activity in all groups. BM MNCs in leukemia patients revealed a four-fold higher telomerase activity than PB (P = 0.005). After induction chemotherapy and response to treatment, telomerase activity decreased to borderline or undetectable levels in PB MNCs in leukemia (P < 0.01). Average telomeres in PB MNCs from pediatric patients were significantly longer (n = 25; 10.9 kbp) than telomeres in PB and BM MNCs from adult healthy donors (7.45 kbp) (P < 0.0001). At diagnosis, telomeres were shorter from BM compared to PB specimens in leukemia (P < 0.05), and two peak TRFs were observed corresponding to the malignant and normal cell clones. With the attainment of remission, the lower TRF peak, reflecting the leukemic population, was lost. In leukemia patients, mean TRFs increased on average 2.2 kbp after induction chemotherapy, but decreased thereafter on consolidation and maintenance chemotherapy (1 kbp). This was comparable to an average telomere loss of 1.2 kbp in PB specimens from ST patients after chemotherapy. In all patients, telomere loss in granulocytes as compared to MNCs was more pronounced with 1.8 vs 1 kbp, respectively (P = 0.014). Our results demonstrate that at diagnosis, telomerase was consistently and highly upregulated in BM and PB specimens in leukemia, decreased after induction therapy, and correlated with remission. BM specimens in leukemia had higher telomerase activity, probably due to the greater leukemic burden than in PB. Telomeres were significantly longer in children than in adults, but shortened as a consequence of chemotherapy with repeated cycles of hematopoietic regeneration. In acute leukemia, with the loss of the leukemic burden after induction chemotherapy, longer mean TRFs were found, a reflection of the repopulation with normal cells. Our findings suggest that telomerase activity may be useful in the management of childhood malignancies. The significance of telomere length shortening in pediatric patients undergoing chemotherapy and possible telomere regeneration after myelosuppressive treatment remain to be determined.

Telomerase and telomere length in the development and progression of premalignant lesions to colorectal cancer

Telomerase and telomere length are increasingly studied as prognostic markers in malignancy. Telomerase is also known to be expressed in certain nonmalignant cells, although generally at low levels. We investigated telomerase activity and telomere length in premalignant, malignant, inflammatory, and normal colon specimens to determine whether significant differences exist and whether telomerase may serve as a marker for early- or late-stage colorectal cancer. Telomerase activity was evaluated in 130 frozen specimens from human colon cancer (n = 50), adjacent normal colon tissue (n = 50), colon polyps (n = 20), and colitis (n = 10) using a modified telomeric repeat amplification protocol assay, and telomere length was assessed by terminal restriction fragment analysis. High to moderate levels of telomerase activity were detected in 90% of colorectal tumors. Weakly positive activity was detected in 10%. None of the normal tissues exhibited telomerase activity. In polyps and colitis, telomerase activity was found in 60% (12 of 20) and 40% (4 of 10), respectively. Telomerase activity in both nonmalignant lesions was 25- to 54-fold lower than that detected in colon cancer (P < 0.001). We found a positive correlation between tumor cell infiltration determined in cryostat sections and telomerase activity (r = 0.886; P > 0.0001). Late-stage tumors (Dukes C + D) demonstrated increased telomerase activity compared to early-stage tumors (Dukes A + B). Telomere restriction fragments in colon tumors had peak values of 4.8 +/- 1 kbp that were significantly and consistently shorter than those of the adjacent normal tissues (7.54 +/- 1.3 kbp), polyps (7.5 +/- 0.7 kbp), and colitis specimens (7.7 +/- 0.5kbp; P < 0.0001). Telomeres were 0.6 kbp longer in tumors with high telomerase activity and in late-stage cancers (Dukes C + D) compared to those in tumors with low telomerase activity and in early-stage cancers (Dukes A + B). Our data demonstrate that telomerase in colon cancer was commonly acquired, and activity was higher than that in polyps and colitis. However, weak telomerase activity was detected in premalignant and inflammatory lesions. Telomeres in colon cancer were considerably shorter, an indication of extensive cell proliferation and population divisions, whereas adjacent normal colon specimens, polyps, and colitis had comparable telomere lengths. Our results indicate that increased telomerase activity occurs in colon cancer cells that have undergone extensive telomere shortening relative to surrounding normal tissues and in which telomerase-induced stabilization of telomeres may be critical for the continued proliferation of the malignant clone. The link between telomerase activity and stage suggests that telomerase is up-regulated as a function of increased tumor cell invasion, tumor progression, and metastatic potential in colon cancer.

Relative contribution of normal and neoplastic cells determines telomerase activity and telomere length in primary cancers of the prostate, colon, and sarcoma

Telomerase and telomere length are increasingly investigated as potential diagnostic and prognostic markers in human tumors. Among other factors, telomerase and telomere length may be influenced by the degree of tumor cell content in tumor specimens. We studied telomerase activity and telomere length with concomitant integration of histopathological data to determine whether both were influenced by the amount of tumor cells. We measured telomerase in 153 specimens: in 51 solid tumor blocks; in 51 cryostat sections; and in 51 adjacent normal tissues from patients with sarcoma (n = 10) and colorectal (n = 11) and prostate cancer (n = 30) using the sensitive and rapid detection telomeric repeat amplification protocol assay. Telomere length was determined by telomere restriction fragment Southern blot analysis. From cryostat sections, tumor cell infiltration was assessed. Telomerase activity was detected in all colorectal tumors and sarcomas, as expected. In primary prostate cancer, however, telomerase activity was less frequently observed (14 of 30, 47%). Moreover, a decreased intensity compared to colon cancer and sarcoma was evident (P < 0.001). The median tumor cell infiltration was significantly higher in sarcoma (65%) and colon (30%) compared to prostate cancer (5%; P < 0.001). There was a positive correlation between tumor cell infiltration and telomerase activity (r = 0.89; P < 0.001). Telomere restriction fragments in tumors were shorter compared to the normal tissues with peak differences in colon, sarcoma, and prostate of 1.8, 2.8, and 1 kilobase pairs, respectively (P < 0.002). Our data suggest the presence of a positive correlation between the degree of tumor cell content in human solid tumors and the level of telomerase activity detected. We demonstrated that the amount of tumor cells also affects telomere restriction fragment analysis. Therefore, with the predominance of normal cells in tumor specimens, telomerase activity measured may not reflect the malignant phenotype, and telomere loss may be underestimated. This phenomenon was most evident in prostate cancer. Our results will have implications for the future when telomerase activity and telomere lengths may be used for early screening, diagnosis, and prognosis determinations and when telomerase inhibitors are applied to clinical practice.