Heath, Elisabeth I.

Background SEA-CD40 is an investigational, non-fucosylated, humanized monoclonal IgG1 antibody that activates CD40, an immune-activating tumor necrosis factor receptor superfamily member. SEA-CD40 exhibits enhanced binding to activating FcγRIIIa, possibly enabling greater immune stimulation than other CD40 agonists. A first-in-human phase 1 trial was conducted to examine safety, pharmacokinetics, and pharmacodynamics of SEA-CD40 monotherapy in patients with advanced solid tumors and lymphoma. Methods SEA-CD40 was administered intravenously to patients with solid tumors or lymphoma in 21-day cycles with standard 3+3 dose escalation at 0.6, 3, 10, 30, 45, and 60 µg/kg. An intensified dosing regimen was also studied. The primary objectives of the study were to evaluate the safety and tolerability and identify the maximum tolerated dose of SEA-CD40. Secondary objectives included evaluation of the pharmacokinetic parameters, antitherapeutic antibodies, pharmacodynamic effects and biomarker response, and antitumor activity. Results A total of 67 patients received SEA-CD40 including 56 patients with solid tumors and 11 patients with lymphoma. A manageable safety profile was observed, with predominant adverse events of infusion/hypersensitivity reactions (IHRs) reported in 73% of patients. IHRs were primarily ≤grade 2 with an incidence associated with infusion rate. To mitigate IHRs, a standardized infusion approach was implemented with routine premedication and a slowed infusion rate. SEA-CD40 infusion resulted in potent immune activation, illustrated by dose dependent cytokine induction with associated activation and trafficking of innate and adaptive immune cells. Results suggested that doses of 10–30 µg/kg may result in optimal immune activation. SEA-CD40 monotherapy exhibited evidence of antitumor activity, with a partial response in a patient with basal cell carcinoma and a complete response in a patient with follicular lymphoma. Conclusions SEA-CD40 was tolerable as monotherapy and induced potent dose dependent immune cell activation and trafficking consistent with immune activation. Evidence of monotherapy antitumor activity was observed in patients with solid tumors and lymphoma. Further evaluation of SEA-CD40 is warranted, potentially as a component of a combination regimen. Trial registration number NCT02376699.

AbstractObjectiveThe purpose of this study was to assess differences in reported information about treatment, integration into care, and respect by self‐identified Black and White individuals with advanced prostate cancer in the United States.Patients and MethodsThis is a prospective cohort study of 701 participants (20% identifying as Black) enrolled in the International Registry for Men with Advanced Prostate Cancer at 37 US sites from 2017 to 2022. Participants were asked six questions from the Cancer Australia National Cancer Control Indicators about their experience with care at study enrollment. Prevalence differences by self‐reported race were estimated using marginal standardization of logistic‐normal mixed effects models (adjusted for age at enrollment and disease state at enrollment), and 95% CIs were estimated using parametric bootstrapping.ResultsMost participants reported a high quality of care for each question. Black participants generally reported higher care quality compared with White participants. Black participants reported more frequently that they were offered a written assessment and care plan (71%) compared with White participants (58%; adjusted difference, 13 percentage points; 95% CI, 4–23). Black participants also reported more frequently being given the name of nonphysician personnel who would support them (64%) than White participants (52%; adjusted difference, 10; 95% CI, 1–20). Prevalence differences did not differ by disease state at enrollment.ConclusionsBlack participants generally reported a higher quality of care compared with White participants. This study calls attention to the need to study potential mediating factors and interpersonal aspects of care in this population to improve survivorship.

256 Background: PARP inhibitors, olaparib and rucaparib recently improved survival outcomes (in the Profound and Triton-2 trials) in pts with aPC harboring HRRm. Notably, ~35% of pts screened for the PROfound trial did not meet eligibility solely due to the lack of adequate quality/quantity of tumor tissue required for CGP (De Bono, NEJM, 2020). cfDNA analysis non-invasively assesses tumor-derived genomic alterations. We evaluated the prevalence of HRRm in a real-world aPC population, who had commercially available cfDNA assay results available. Methods: cfDNA based CGP (using a clinically-validated 73- to 74-gene panel i.e. Guardant360 or G360) from consecutive aPC pts between 11/2016–8/2020 were used for detection of HRRm. Frameshift and nonsense mutations were included as pathogenic. Variants of unknown significance were excluded. In this unmatched study, the prevalence of each HRRm was compared with those reported in literature using the chi square test. Results: cfDNA CGP from 7701 aPC pts were available for interrogation of BRCA1/BRCA2 mutations, & from 4671 aPC pts for ATM mutations. Prevalence of BRCA1 and 2 as detected by cfDNA was similar to historical CGP of primary tissue. Prevalence of BRCA1 was higher than historical CGP of metastatic tissue. Prevalence of ATM in cfDNA was higher than historic tumor tissue CGP but similar to prior reports from cfDNA testing (Table). Conclusions: In this large real-world population of pts with aPC undergoing routine cfDNA CGP by a CLIA certified lab, prevalence of HRRm was similar (or higher for BRCA1 and ATM) to what has been previously reported from the tumor tissue. These data provide the rationale for utilizing cfDNA CGP as a routine test for detection of HRRm in men with aPC to identify men who are candidates for PARPi. [Table: see text]

Abstract CD40 is a co-stimulatory receptor of the TNF receptor superfamily expressed on antigen presenting cells (APCs). Antibodies targeting CD40 may have therapeutic benefit via multiple mechanisms including innate immune activation that can support generation of antigen-specific, antitumor T cell responses, and binding to CD40-expressing cancer cells leading to antibody-mediated target cell killing. Multiple CD40-directed antibodies are in clinical development and differ by immunoglobulin isotype, affinity to CD40, and selectivity for FcγR-binding. These alterations could lead to differences in pharmacodynamic and antitumor activity. SEA-CD40 is an agonistic non-fucosylated, humanized IgG1 monoclonal antibody directed against CD40. SEA-CD40 has enhanced FcγRIIIa binding (~10x greater than parent IgG1 antibody) that drives increased effector function, resulting in more potent immune stimulatory activity than antibodies with muted or selective FcγR binding. The enhanced effector function of SEA-CD40 may confer greater immune stimulation and antitumor activity relative to other CD40-directed therapeutics. Preclinically, SEA-CD40 exposure results in a distinct signature of responses including activation of APCs, CD8+ and CD4+ T cells and NK cells, and targeted depletion of CD40+ B cells. SEA-CD40 demonstrates superior activity compared to other CD40-targeted antibodies in vitro and in vivo, suggesting that the enhanced effector function is critical for optimal immune cell agonism. For example, SEA-CD40 drove in vitro ADCC activity 100-fold above the parent antibody and exhibited robust ADCC with the low and high affinity FcγRIIIA genotype. At matched dose levels in cynomolgus monkeys, SEA-CD40 induced circulating cytokines and sustained B cell depletion that were up to 50-fold above that induced with the parent antibody. The SEA-CD40 signature of activation translates to increased antitumor activity as a single agent and in combination with standard of care treatments in preclinical models, suggesting the potential for beneficial combination therapy in the clinic. The SEA-CD40 immune signature was confirmed by pharmacodynamic changes in an ongoing phase 1 clinical trial in patients with relapsed/refractory metastatic solid tumors (NCT02376699). SEA-CD40 treatment induced dose-dependent increases in circulating cytokines and chemokines associated with myeloid and lymphoid immune activation and trafficking. SEA-CD40 treatment also resulted in activation of CD4+ and CD8+ T cells and CD40-targeted B cell depletion in the periphery. These findings support continued clinical evaluation of SEA-CD40. The ongoing phase 1 clinical trial is actively enrolling and includes a cohort in pancreatic cancer assessing the combination of SEA-CD40, gemcitabine, nab-paclitaxel, and pembrolizumab. Citation Format: Haley Neff-LaFord, Juneko E. Grilley-Olson, David C. Smith, Brendan Curti, Sanjay Goel, Timothy M. Kuzel, Svetomir N. Markovic, Olivier Rixe, David L. Bajor, Thomas F. Gajewski, Martin Gutierrez, Elisabeth I. Heath, John Thompson, Sahar Ansari, Shyra Gardai, Celine Jacquemont, Michael Schmitt, Andrew L. Coveler. SEA-CD40 is a non-fucosylated anti-CD40 antibody with potent pharmacodynamic activity in preclinical models and patients with advanced solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5535.

e20626 Background: It is important to increase our understanding of recruitment barriers in the elderly population to improve their participation in clinical trials. The primary objective of this study was to describe the demographics, treatment, toxicity, and overall survival (OS) of all patients ≥ 65 years who presented to the Phase I clinical trials service at KCI between 1995–2005. Methods: Patient demographics, co-morbidities, tumor type, reason not enrolled on a Phase 1 clinical trial, toxicities, and OS were obtained by retrospective chart reviews. The patients were divided into 3 mutually exclusive groups: patients considered but not enrolled (PC), enrolled but not treated (PE), and treated (PT). OS was compared across these three groups. Results: 216 patients met the study criteria. Of these, there were 114 PC, 7 PE, and 95 PT. Lack of enrollment was due to ineligibility (30%), loss to follow-up (12%), refusal (8%), or no trial available (2%). Median age was 71 years, 63% were males and 87% were Caucasian. 59% had performance status (PS) 1; 16% had PS 2. 66% of patients had a history of cardiovascular disease but renal, liver, hematological diseases were found in less than 7% of patients at baseline. Colorectal (27%), lung (15%) and prostate (8%) were the 3 most common cancers. 54% received a cytotoxic agent, 62% a biologic agent, and 17% combination therapy. The 3 most common Grade 3–4 toxicities were: 15% leucopenia, 11% electrolyte abnormalities, and 4% anemia. The median OS for PC, PE, and PT was 3.9 mos, 2.2 mos, and 8.4 mos, respectively (p < 0.001 between any pair). However, PS 0–1 patients comprised 47%, 75%, and 73% of those 3 patient subgroups, respectively. Conclusions: More than half of the elderly patients initially considered for Phase 1 clinical trials at KCI were not enrolled due to ineligibility, refusal, or lost to follow up. Phase I chemotherapy appears feasible in patients age ≥ 65 years old. OS was significantly longer for patients treated on Phase I trials compared to those who were not, although that may be confounded by PS differences. More detailed OS comparisons will be presented. No significant financial relationships to disclose.

15553 Background: 17-Allylamino-17-Demethoxygeldanamycin (17-AAG) is a benzoquinone ansamycin antibiotic with anti- proliferative activity in several mouse xenograft models including prostate cancer models. Serum IL-6, IL-8, and maspin are potentially important markers of prostate cancer biology. Methods: Patients (pts) with metastatic, hormone-refractory prostate cancer progressing on at least one prior systemic therapy with rising PSA were eligible. All pts received 17-AAG at a dose of 300 mg/m2 IV weekly for three out of four weeks. Primary objective was to assess the PSA response (50% decrease in PSA). Secondary objectives included Adverse Events (AEs) and correlative serum markers including IL-6, IL-8 and maspin levels. A Simon two-stage design required a total of 25 pts with early termination if < 2 responses occurred among the 1st 16 eligible patients. Results: Seventeen pts were enrolled of which 15 were deemed eligible. Median age was 68 and median PSA was 252 ng/mL. Pts received 17-AAG for a median number of 2 cycles. No pt had a PSA response. No grade 4/5 AEs occurred. Grade 3 AEs included fatigue (4 pts), lymphopenia (2 pts) and back pain (2 pts). The median PSA progression free survival was 1.8 months (95% CI: 1.3–3.4 months). The six-month overall survival was 61% (95% CI: 37%-100%). Due to the lack of PSA response, accrual was stopped per study design. At day 15, the median IL-6 and IL-8 increase from baseline was 0.4 pg/ml (p=0.57) and 3 pg/ml (p=0.73), respectively. Maspin levels had day 15 increase of 6-fold (p=0.44). At treatment failure (TF), the median IL-6 increase from baseline was 4.47 pg/ml (p=0.03) and IL-8 decrease was 1.8 pg/ml (p=0.31). Maspin levels had a 29-fold increase at TF (p=0.09). Conclusions: 17-AAG did not show any activity with regards to PSA response. Serum IL-6 was significantly increased at the time of TF. Further evaluation of 17-AAG at a dose of 300 mg/m2 IV weekly in this patient population is not warranted. No significant financial relationships to disclose.

368 Background: SGN-75 is an antibody-drug conjugate composed of a humanized anti-CD70 mAb conjugated to the microtubule-disrupting agent MMAF via a plasma-stable linker. Upon binding to CD70, SGN-75 internalizes and releases cys‑mcMMAF which binds tubulin and induces G2/M arrest and apoptosis. Methods: A phase 1, dose-escalation, multicenter study was initiated to investigate the safety, tolerability, PK, and antitumor activity of SGN-75 monotherapy in pts with CD70-positive metastatic RCC or relapsed/refractory NHL (ClinicalTrials.gov #NCT01015911). SGN-75 was administered IV in cohort-specific doses using 2 schedules [every 3 weeks (q3wk) or weekly (days 1, 8, 15 q28 days)] at doses of 0.3-4.5 mg/kg. Pts were eligible to receive treatment until PD. Results: A total of 58 pts (39 RCC/19 NHL) with a median age of 60.5 yrs (range 30-82) were treated. The MTD was 3 mg/kg q3wk; 2 pts had DLTs at 4.5 mg/kg q3wk (NHL pt had neutropenia and RCC pt had proteinuria). Weekly dosing (N=11) was terminated at the 0.6 mg/kg dose level after 2 pts with NHL developed idiopathic thrombocytopenic purpura. At the MTD, adverse events (AEs) in ≥30% of RCC pts (N=21) were fatigue (52%), dry eye (48%), nausea (38%), constipation (33%), and corneal epithelium defect (33%). AEs ≥ Grade 3 in >10% of RCC pts treated at the MTD were corneal epithelium defect (19%) and thrombocytopenia (14%). PK analysis suggested that SGN-75 exposure was approximately dose-proportional with a mean terminal half-life of 6-11 days. Among the 32 pts with RCC treated in the q3wk schedule, all had prior nephrectomy and a median of 3 prior therapies (range 1-6). All pts had clear cell RCC, with the exception of 2 pts who had papillary RCC. Most pts had high CD70 expression by central IHC analysis (2 or 3+, 80-100% of cells). The best clinical responses of RCC pts treated q3wk were 2 PR, 12 SD, 12 PD, and 6 were not evaluable. Durations of response for the 2 responding pts were 23 and 41 weeks. The median duration of disease control (PR and SD) was 46.4 weeks [95% CI (12, 46)]. Conclusions: SGN-75 monotherapy was generally well tolerated in pts with metastatic RCC. Evidence of antitumor activity was observed in heavily pretreated RCC pts and further studies of SGN-75 in RCC are warranted. Clinical trial information: NCT01015911.

Abstract Purpose: 17-Allylamino-17-demethoxygeldanamycin (17-AAG) is a benzoquinone ansamycin antibiotic with antiproliferative activity in several mouse xenograft models, including prostate cancer models. A two-stage phase II study was conducted to assess the activity and toxicity profile of 17-AAG administered to patients with metastatic, hormone-refractory prostate cancer. Experimental Design: Patients with at least one prior systemic therapy and a rising prostate-specific antigen (PSA) were eligible. Patients received 17-AAG at a dose of 300 mg/m2 i.v. weekly for 3 of 4 weeks. The primary objective was to assess the PSA response. Secondary objectives were to determine overall survival, to assess toxicity, and to measure interleukin-6, interleukin-8, and maspin levels and quality of life. Results: Fifteen eligible patients were enrolled. The median age was 68 years and the median PSA was 261 ng/mL. Patients received 17-AAG for a median number of two cycles. Severe adverse events included grade 3 fatigue (four patients), grade 3 lymphopenia (two patients), and grade 3 back pain (two patients). The median PSA progression-free survival was 1.8 months (95% confidence interval, 1.3-3.4 months). The 6-month overall survival was 71% (95% confidence interval, 52-100%). Conclusions: 17-AAG did not show any activity with regard to PSA response. Due to insufficient PSA response, enrollment was stopped at the end of first stage per study design. The most significant severe toxicity was grade 3 fatigue. Further evaluation of 17-AAG at a dose of 300 mg/m2 i.v. weekly as a single agent in patients with metastatic, hormone-refractory prostate cancer who received at least one prior systemic therapy is not warranted.