Abstract OT2-01-09: PALINA: A phase II safety study of palbociclib in combination with letrozole in African American women with hormone receptor positive HER2 negative advanced breast cancer

Background:Insufficient data exist to describe the hematological safety of palbociclib in African American women (AAW) who are known to have a high incidence of benign ethnic neutropenia (BEN). The studies that led to the FDA approval of palbociclib (PALOMA 1 and 3) only included participants with baseline absolute neutrophil count (ANC) of ≥1500/mm3. The standard lower limit of ANC of 1500/mm3 for initiation of treatment in those with BEN has been previously challenged. In this current study, we propose to lower the ANC cutoff for enrollment to 1000/mm3.

Trial design: PALINA is a phase II study evaluating the hematological safety of palbociclib with letrozole in 35 AAW with hormone receptor (HR) positive HER2 negative advanced breast cancer and ANC ≥1000/mm3. Patients enrolled will receive palbociclib 125mg daily for 21 days followed by 7 days off and letrozole 2.5mg daily. For patients enrolled with baseline ANC between 1000-1499/mm3, initial dose of palbociclib will be 100mg daily for 21 days followed by 7 days off. Presence of Duffy Null Polymorphism (SNP rs2814778) as a predictive marker for neutrophil count will be assessed at baseline. Metabolite and exosomal signature (proteins and RNA) of drug resistance will be evaluated at different time points.

Main eligibility criteria: Self-identified Black, African or AAW of ≥ 18 years of age with proven diagnosis of advanced HR-positive, HER2-negative breast cancer; ECOG performance status 0-2; ANC ≥ 1,000/mm3 and no prior receipt of CDK4/6 inhibitors.

Specific aims: The primary endpoint is the proportion of patients who complete planned oncologic therapy without the development of a hematological event defined as episodes of febrile neutropenia and treatment discontinuation due to neutropenia. Additional endpoints include: number of patients who required dose delays or dose reductions in palbociclib attributed to neutropenia; rate of grade 3/4 neutropenia; clinical benefit rate at 24 weeks; correlations between metabolite and exosomal signature with disease response; correlations between baseline ANC prior to cancer diagnosis and the Duffy Null polymorphism with hematological safety.

Statistical methods: The study is designed to assess the rate of completion of planned therapy in the absence of a hematological event defined as episodes of febrile neutropenia and treatment discontinuation due to neutropenia. Simon's two-stage design with a maximum of 35 patients is used. The null hypothesis that the true completion rate is 60% will be tested against a one-sided alternative. This design yields a type I error rate of 0.05 and power of 80% when the true completion rate is 80%.

Present accrual and target accrual: The Institutional Review Board at Georgetown University Medical Center (GUMC) has approved the study. Enrollment of the first patient is expected in July 2016 with a total of 35 patients planned to be recruited. The recruitment sites are MedStar Georgetown University Hospital and other hospitals of the Georgetown MedStar Cancer Network, Hackensack University Medical Center and University of Alabama at Birmingham. This trial is funded by an ASPIRE Breast Cancer Research Award from Pfizer.

Citation Format: Lynce F, Shajahan-Haq A, Cai L, Graham D, Gallagher C, Mohebtash M, Kamugisha L, Novielli N, Castle J, Forero A, Isaacs C. PALINA: A phase II safety study of palbociclib in combination with letrozole in African American women with hormone receptor positive HER2 negative advanced breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-09.

Abstract P3-10-02: Increasing participation in research - breast cancer (Inspire-BrC)

Background: Increasing Black patients' participation in cancer clinical trials is important because of the population's lower survival rate. Accrual for Blacks is the lowest of all groups at 0.5-1.5%. Our study aims to increase trial participation rates among Black breast cancer patients by testing the effectiveness of a culturally tailored video intervention on the decision to participate in a clinical trial.

Methods: We hypothesized that the intervention would increase clinical trial enrollment by 6 percentage points compared to our 2012 enrollment baseline of 6% (22/384). Self- identified Black patients with invasive breast cancer at 5 MedStar Hospitals watched a 15' video about clinical trials, targeting six cultural and attitudinal barriers to participation. The Attitudes and Intention to Enroll in therapeutic clinical Trials (AIET) pre-/post-/follow-up tests with 31 items was used to determine the impact of the video on three domains: actual trial enrollment; likely participation in trials; and attitudes toward trials. The pre-test was conducted at baseline; post-test immediately after video; and follow-up 7-21 days after the intervention. Participants were followed for 6 months to assess trial enrollment status. Descriptive statistics were used to describe study subjects with respect to basic characteristics; means and standard deviations for continuous variables; and frequencies and percentages for categorical variables. Repeated measures analysis of variance was used to examine whether the changes in attitudinal barriers were statistically significant over time. The primary outcome measure was the proportion of Black breast cancer patients who signed consent and/or enrolled in a therapeutic clinical trial.

Results: From Mar/2014 to Sept/2015, 279 patients were approached to join INSPIRE-BrC prior to discussion about therapeutic clinical trials; 52 declined participation. 208 signed consent and 200 completed it. Average age was 59 yrs (SD=12), 75% were stage I-III; 29% were married; 85% had 1 or more children; 29% attended some college or technical school; 53% had private insurance, 31% Medicare, 16% Medicaid; and 53% had a household income <$40,000/yr. A total of 41 INSPIRE-BrC participants (20.5%) signed consent and 29 (14.5%) enrolled onto a therapeutic study (one-sided p=0.027 vs H0: P=0.06). Pre-video, 52% of patients expressed that it was likely they would participate in a hypothetical therapeutic clinical trial; immediately post-video, 67% (p=<0.001) and 7-21 days after the intervention, 64% (p=0.003). Among 31 AIET items, 25 (81%) showed statistically significant and positive change after the intervention. Specifically, trust in the doctor increased and, suspicion in trials decreased (p<0.001). Further, patient views on fairness for treatment of poor people and Blacks became significantly more positive (p<0.001).

Conclusion: Study findings show that the video is a promising tool for rapid dissemination of a theory-driven, evidence-based model to enhance clinical trial accrual among Black cancer patients. The video also has the potential to positively change attitudes about clinical trial participation.

The study was supported by the Breast Cancer Research Foundation.

Citation Format: Swain S, Robinson BN, Newman AF, Tefera E, Herbolsheimer P, Nunes R, Gallagher C, Randolph-Jackson P, Omogbehin A, Dilawari A, Pohlmann P, Mohebtash M, Ottaviano Y, Mohapatra A, Lynce F, Mete M. Increasing participation in research - breast cancer (Inspire-BrC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-10-02.

Abstract P5-16-06: A phase 2 randomized trial of docetaxel (DOC) alone or in combination with therapeutic cancer vaccine, CEA-, MUC-1-TRICOM (PANVAC)

Background: A previous phase 1/2 trial of PANVAC, a poxviral based cancer vaccine, suggested clinical efficacy in some patients (pts) with breast and ovarian cancer and evidence of immunologic activity. Preclinical data showed DOC can modify tumor phenotype, making tumor cells more amenable to T-cell mediated killing. The goal was to determine if DOC and PANVAC could synergize and improve clinical outcomes compared with DOC alone.

Methods: This is an open-label randomized phase 2 multi-center trial designed to enroll 48 pts with metastatic breast cancer to receive DOC in combination with PANVAC (A) or alone (B). Cross-over was allowed so that pts randomized to B could receive the vaccine upon progression. Eligibility included ECOG performance status <1 and normal organ and immune function with no limits on previous lines of therapy, but pts may not have received DOC for metastatic disease. Her2+ pts on trastuzumab were allowed to continue trastuzumab on trial. All pts received DOC 35mg/m2 weekly × 3 doses during 28-day cycles. Pts on A were “primed” with recombinant vaccinia-PANVAC study day 1. Three weeks later, they began 28-day cycles of DOC with “boost” recombinant fowlpox-PANVAC given on day 1, given until progression. CT and bone scans were performed after 3 cycles and then every 2 cycles. 1° endpoint was PFS., with a phase 2.5 statistical design, with the intent of identifying a trend toward benefit to guide a larger trial design. A p value of 0.10 is considered a strong trend. 2° endpoints included overall survival and immunologic correlative studies. Immunologic assays included analysis of T cell and NK cell activation, presence and activity of regulatory T cells, and ELISPOT assays. Immune correlative analysis was done using multiparametric flow cytometry analysis of immune cell subpopulations from peripheral blood mononuclear cells (PBMCs) of pts and comparing those findings using Boolean logic with the immune assays and clinical outcomes.

Results: Enrollment of 48 pts completed in February 2012 (A, n=25; B, n=23). Five pts remain on treatment (2 on A, 3 on B). Pt and tumor characteristics were well matched. Analysis through August 2, 2012 (median follow-up of 5.1 months for pts on study), indicates PFS is 6.6 vs. 3.8 months in A vs. B (p = 0.12, HR=0.67, 95% CI: 0.34 to 1.31). Analysis of the adverse events on both arms demonstrated very little difference between the two groups. The only statistically significant differences were increases in the frequency of grade 1 and 2 edema (p = 0.018) and injection site reactions (p <0.0001) in the combination arm. Immune analysis and correlation to pt clinical outcomes are ongoing and will be available for presentation at the time of the meeting. There are not yet enough events to perform a comparison of overall survival in the two groups.

Conclusion: This randomized study suggests the combination of PANVAC with DOC in metastatic breast cancer may provide a clinical benefit compared to DOC alone. The clear separation of the curves indicates potential benefit, which is not statistically significant, likely due to the small number of pts enrolled. This study was hypothesis generating and may provide both rationale and statistical assumptions for a larger definitive randomized study.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-16-06.

Phase I trial of targeted therapy with PSA-TRICOM vaccine (V) and ipilimumab (ipi) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC)

5144

Background: There are few treatment options for mCRPC pts. Immunotherapy + adjuvant immunomodulators is a promising modality. PSA-TRICOM V is composed of poxviral vectors encoding PSA and 3 costimulatory molecules (ICAM-I, LFA-3, and B7.1) and has clinical activity in mCRPC. Ipi blocks CTLA-4, a T-cell downregulatory receptor, has clinical activity in mCRPC as monotherapy and has also been shown to enhance anti-tumor responses in combination with V in preclinical studies. Methods: Pts received V and GM-CSF q 4 weeks in 4 sequential cohorts of escalating doses of ipi at 1, 3, 5, and 10 mg/kg (DL1–4 respectively). After 6 courses of ipi, pts could receive a maintenance dose q 3 months (mo) until progression. Results: Study accrual is complete with 30 pts. There was no DLT and no > G2 adverse event (AE) attributed to V. There were 20 ≥ G2 immune-related AE (irAE): 0/3, 2/6, 5/6 and 13/15 pts on DL1–4, respectively. There was no evidence of clinical benefit in the 6 pts who had prior chemo on DL1 and 2, so subsequently we excluded pts with prior chemo. Median TTP for 9 chemo-naïve pts treated on DL2 and 3 was 6.1 mo (2.9–11.6 mo). Median PSA doubling time (DT) ↑ from 2.2 mo at baseline to 3.7 on study (p = 0.17). 5 of 9 had ≥ 50% ↓ in PSA from peak during study and 1 had a sustained ↓ PSA > 95% from baseline. 4 of these pts had stable disease (SD) for ≥ 6 mo and 2 had unconfirmed partial responses by RECIST. Of the 15 pts on DL4, to date 9 have had SD for ≥ 6 mo (2 ≥ 12 mo); 4 remain on trial. 1 had a sustained ↓ in PSA > 99% from baseline and is still on study after 12 mo. Median PSA DT ↑ > 3-fold from 2.6 mo at baseline to 8.2 on study (p = 0.01) in DL4. The 24 chemo-naïve pts had PSA DT ↑ from 2.5 to 6 mo (p = 0.003). 14 of 30 pts had a PSA ↓ from baseline or peak PSA on study. 2 of 14 had no irAE, 12 showed ≥ G2 irAE temporally associated with PSA ↓. 5 of 9 pts had > 2–5 fold ↑ in T-cell responses by ELISPOT assay and 4 of 13 had significant ↓ in their IL-6 levels. Immune responses appeared to correlate with clinical activity. Conclusions: This combination has clinical activity in pts with chemo-naïve mCRPC and seems to correlate with immune responses. It is associated with manageable side effects; however, further studies are required to see if the combination is more effective than either agent alone.

No significant financial relationships to disclose.

Immunotherapy with MUC1/CEA vaccine alone or combined with chemotherapy in patients with metastatic breast cancer

Abstract #4123

Background: PANVAC is a recombinant pox viral vaccine that contains transgenes for the tumor-associated antigens (TAAs), MUC1 and CEA. PANVAC also contains three T-cell co-stimulatory molecules (B7.1, LFA-3, ICAM-1) to enhance immune response. Clinical studies with a similar vaccine have shown docetaxel does not diminish specific T-cell responses to the TAAs delivered in the pox viral vaccines. We are evaluating the use of PANVAC in two ongoing trials in patients with metastatic breast cancer.
 Methods: The primary end point of these two phase II trials is progression-free survival (PFS). As secondary end point specific T-cell response is measured using ELISPOT assay in HLA-A2 patients. One study uses vaccine alone, given monthly by SC injections and is accompanied by 4 days of low dose GM-CSF. The other trial randomizes to either vaccine + docetaxel or docetaxel alone; giving the same V regimen (as the first study) on day 1 followed by docetaxel at 35 mg/m2 on days 2, 9, and 16 of each 28 day cycle. The chemotherapy alone arm uses the same docetaxel dosing.
 Results: Twenty three patients have been accrued with a median age of 57.6 (31-75) years. Sixteen patietns had ER/PR+ tumors. The patients had a median of 4 (0-6) previous chemotherapy regimens; their median time since their last chemotherapy was 2 months with a 10th – 90th percentile of 1-8 months. Vaccine is well tolerated with few grade 3 and no grade 4 adverse events. Most of the grade 1-2 toxicities were self-limited site reactions and flu-like symptoms. Three of 13 patients on vaccine alone study have shown measurable clinical benefits. Two were on study for 6 months, of whom one had significant improvement in pain with reduction in vertebral lesions on MRI; another had a sustained >20% decrease in bulky liver metastases. A third patient on vaccine alone was on study for 9 months with reduction in her mediastinal lymphadenopathy. Of the 6 patients who received vaccine + docetaxel, 5 had measurable disease. One achieved PR by RECIST criteria and remained on study for 19 months; another had a 50% reduction in the diameter of a chest wall lesion. A third patient with bone only disease was on study for 12 months with significant improvements on her bone scan.
 Conclusions: Vaccine given alone or in combination with docetaxel is shown to be safe in patient with metastatic breast cancer. There is preliminary evidence that there may be some clinical benefit from vaccine alone as well as its combination with chemotherapy. Confirmation of these results and PFS determination requires additional patient enrollment and follow up in both studies. Furthermore, immunologic studies including functional analysis of CD4 and CD8 T-cells will be performed to help elucidate the immune responses these regimens may elicit.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4123.