Outcomes in late-line systemic treatment in GISTs: Does sequence matter?

11542

Background: Ripretinib (R) is approved for 4th line treatment of GIST based on superior PFS and OS compared to placebo in a phase 3 study, with RR of 11.8% and PFS of 6.3 months (mo). In addition to having high potency against PDGFRA D842V, avapritinib (A) showed activity in 4th or later lines for KIT mutated patients (pts). The RR was 17% and median duration of response was 10.2 mo from a phase 1 study. It is not known if pts receiving R benefit from A after progression or vice-versa. We retrospectively reviewed outcomes of R and A to determine if sequence affects outcomes. Methods: Pts diagnosed with GISTs and treated with both R and A at UTMDACC from Jan 2016 to Dec 2021 were included. Pts were separated into R-A (RA) or A-R sequence (AR) and outcomes were tabulated. Descriptive statistics were used to summarize characteristics and genetic profiles. Differences between RA and AR groups were calculated using Fisher’s exact. Response was evaluated using RECIST. Kaplan-Meier and Log-rank test were used to estimate and compare PFS and OS between groups. Results: Twenty pts were included in the study; 12 in RA and 8 in AR. Median age was 55 years (R:29.7-76.3). Most pts had small bowel primary (11/20, 55%) followed by stomach (4/20, 20%). All baseline characteristics and mutations were equitably distributed between RA and AR. RR of R was 17% and 14% in RA and AR groups, respectively and RR of A was 33% and 29% in RA and AR, respectively (Table). None of the pts with secondary exon 13 mutations responded to R or A. The drug administration sequence did not affect RR (p = 0.7, 0.62 in R, A). The PFS of the second drug administered, was shortened. PFS did not differ based on type of KIT mutation. Median OS from diagnosis in RA and AR groups were 121.8 (58.2-NR) and 171.3 (73.3-NR) mo, respectively and median OS from start of RA and AR was 43.9 (23.0-NR) and NR (11.5-NR) mo, respectively. Neither difference was statistically significant. Conclusions: Both R and A are efficacious in later lines of treatment, with greater benefit from the agent used first. Although, the combined PFS was numerically higher in AR compared to RA (20.5 vs 15.2 mo), the OS was not different. Currently, R is the only drug approved in the 4th or later lines in KIT-mutated GIST. [Table: see text]

A phase 1/2 dose-escalation and dose-expansion study of ZN-c3 in combination with gemcitabine in adult and pediatric subjects with relapsed or refractory osteosarcoma

TPS11584

Background: Osteosarcoma (OS) is the most common primary bone malignancy of childhood and adolescence with 5-year survival rates of 65-70% for localized disease and < 30% for de novo metastatic disease or recurrent disease. Pooled analysis of previous phase 2 trials by the Children’s Oncology Group has determined a 4-month event-free survival (EFS) of 12%. The Wee1 kinase helps regulate DNA damage repair at the G2-M checkpoint. In the presence of DNA damage, the Wee1 kinase is activated, arresting cells in the G2 phase and preventing entry into the M phase. Inhibition of the Wee1 kinase abrogates the G2-M checkpoint, forcing cancer cells to undergo unscheduled mitosis even in the presence of DNA damage, leading to mitotic catastrophe. However, the Wee1 kinase is often upregulated in OS, preserving the G2-M checkpoint and allowing tumor growth and metastases. Additionally, up to 90% of OS tumors have alterations in p53, a critical protein in the regulation of the G1-S checkpoint, especially in relapsed or refractory cases. With a dysfunctional G1-S checkpoint, cancer cells further rely on G2-M checkpoint to repair DNA damage and preserve genomic integrity. Prior studies have demonstrated that pharmacologic inhibition of the Wee1 kinase produced cell death in OS cell lines and patient-derived xenografts. While p53 mutational status appeared to modulate efficacy of the Wee1 kinase inhibitor, activity was observed in p53 wild type, mutant and null cell lines. Combination therapy studies have also been performed, demonstrating potential synergism with gemcitabine. As expected, by precipitating DNA damage, susceptibility to inhibition of the G2-M checkpoint is further increased. Methods: NCT04833582 is an ongoing, open label, multicenter, phase 1/2 clinical trial to evaluate the activity of ZN-c3, an oral Wee1 inhibitor, in combination with gemcitabine in subjects ≥12 years and ≥40 kg, with relapsed, refractory OS. Subjects are dosed once daily, continuously with ZN-c3 and receive gemcitabine 1000 mg/m2 on days 1 and 8 of 21-day cycles. Up to 18 subjects are expected to enroll in the phase 1 portion based on a typical 3 + 3 escalation design; ̃60 subjects will be enrolled in the phase 2 portion, consisting of three stages: futility, promising clinical activity, and improved precision for clinical activity. The first two stages follow a Simon two-stage optimal design with 30 subjects, to differentiate an EFS rate at 18 weeks between 12% and 36% (which may be considered a more suitable endpoint for OS, compared with radiographic response). Tumor and skin punch biopsies are incorporated into the trial to identify potential biomarkers of treatment response. Subjects must be able to swallow oral tablets and have measurable disease by RECIST v1.1; prior exposure to gemcitabine is allowed. Global enrollment began August 1, 2021, and is ongoing. Clinical trial information: NCT04833582.

A phase II multi-arm study to test the efficacy of oleclumab and durvalumab in specific sarcoma subtypes

TPS11594

Background: Anti-PD 1/PD-L1 blockade alone or in combination with anti-CTLA4 have yielded suboptimal results in most sarcoma subtypes. CD73, an ectonucleotidase, catalyzes the rate-limiting step for adenosine production in the extracellular space, which then aids tumors in evading immune recognition and destruction. Oleclumab, a monoclonal antibody (mAb) selectively binds and inhibits the activity of CD73, and preclinical data suggests additive activity with durvalumab, a mAb that blocks PD-L1. We designed a trial combining oleclumab and durvalumab in certain sarcoma subtypes, selected based on modest activity with anti-PDL-1 and intense staining with CD73 in the tumor microenvironment. Methods: This phase 2 study (NCT04668300) is enrolling patients with age ≥18 years with recurrent/metastatic angiosarcoma (cohort 1) or dedifferentiated liposarcoma (DLPS) (cohort 2) and ≥12 years with recurrent/metastatic osteosarcoma (cohort 3), who have received at least one prior systemic therapy but are checkpoint inhibitor naïve and have measurable disease. Each treatment cycle is 28 days with oleclumab administered at 3000 mg i.v. every 2 weeks x 5 doses, and then every 4 weeks and durvalumab administered at 1500 mg i.v every 4 weeks. Tumor assessments are based on RECIST 1.1 and immune-related response criteria (irRC) and performed at baseline, and every 8 weeks after start of therapy, with an additional scan at 12 weeks for confirmation of response. Planned sample size is ≤ 25 pts in each arm. The primary efficacy endpoint for cohorts 1 and 2 is response rate (RR) at 4 months (per RECIST 1.1). The primary efficacy endpoint for cohort 3 is event free survival (EFS) rate at 4 months. If there is a high probability that the RR4 months is unlikely to be at least 20% for cohorts 1 and 2 or the EFS4 months is unlikely to be at least 40% for cohort 3 then the accrual of the corresponding cohort will be halted. The cohorts will be monitored separately for both futility and toxicity in groups of 5 after a minimum of 10 patients have been enrolled in each cohort. Secondary endpoints for the study include safety, best RR by RECIST and irRC, median PFS, and OS. Core needle biopsies and blood samples are collected at baseline and early on-treatment (week 6). Fresh flow cytometry is being performed to assess changes in T-cell activation, proliferation, and function and CD73 expression in the membrane and cytoplasm is being assessed by immunohistochemistry. Localization of tumor-infiltrating lymphocytes and engagement of the PD-1/PDL1 axis is being assessed using multiplex immunofluorescence staining. As of Jan 30th, 2022, twenty-two patients have initiated study treatment, 3 in cohort 1, 12 in cohort 2, and 7 in cohort 3. Clinical trial information: NCT04668300.

Clinical characteristics and outcomes of adult alveolar rhabdomyosarcoma (ARMS) patients on front-line therapies: An MD Anderson Cancer Center (MDACC) case series

e23548

Background: Rhabdomyosarcomas are the most common soft tissue sarcoma in children, and the prognosis of pediatric ARMS has improved with the use of multi-modality therapies. However, ARMS in adults is rare, and long-term outcomes continue to be poor. This study aimed to evaluate clinical outcomes of an adult ARMS population on different front-line systemic chemotherapies, particularly the vincristine/doxorubicin/ifosfamide (VDI) regimen. Methods: Adult fusion-positive confirmed ARMS patients over the age of 18 years (y) treated at MDACC from 2004 to 2018 were identified in our patient registry. Descriptive clinical statistics including staging, front-line chemotherapy, multimodal therapy usage, and survival analyses were performed. Results: 49 patients were identified, with mean age of 34.9 y (range 18y - 67y), and 53% were male. Most patients were white (53%, 26 pts), and the most common primary tumor site was the parameningeal space (63%; 31 pts). Patients were either intermediate (67%) or high clinical risk (33%). Most patients were IRSG clinical group IIIa (36%), IIIb (20%) or IV (33%) and were classified clinical stage 3 (49%) or 4 (33%). Of all patients at diagnosis, 71% had nodal disease and 32% were metastatic. Radiotherapy and surgery were given with upfront chemotherapy in 33 pts (67%) and 24 pts (49%) respectively, with 19 patients receiving both. Median OS for the entire cohort was 3.6 years. Doxorubicin containing chemotherapy regimens trended to worse OS than non-doxorubicin containing regimens (2.3 yrs vs 4.0 yrs, p = 0.355). Comparing patients who received VDI (19 pts) vs non-VDI (30 pts; 13 received Actinomycin D, 12 received doxorubicin in different regimens, and 5 received neither), median OS was 1.8 yrs vs 3.8 yrs (p = 0.283) respectively. There were similar number of front-line chemotherapy cycles (8.5 vs 9.5 cycles), high clinical risk (26% vs 37%) and metastatic disease (21% vs 36%) in the VDI vs non-VDI cohorts. Patients receiving upfront radiation had improved survival (3.7 vs 1.5 yr, p = 0.01), but this is likely confounded by those with metastases being less likely to receive upfront radiation. Conclusions: In this single center retrospective analysis of adult ARMS patients, survival outcomes continue to be similar to historical outcomes. There was no statistically significant OS difference in patients who did or did not receive doxorubicin containing front-line chemotherapy regimens, or in particular VDI therapy, although there was a trend to decreased OS. However, limitations to this study include limited sample size, non-randomization to treatment selection, and possible biases in patient selection for different chemo regimens. Based on these observations, randomized prospective studies are necessary to delineate which frontline chemotherapy regimen is most beneficial in this rare tumor in adults.

Satisfaction with and recommendations to improve telehealth visits among adolescents and young adults with cancer during the COVID-19 pandemic

280

Background: The COVID-19 pandemic has negatively impacted morbidity, mortality, and economic status globally. Adolescents and young adults (AYAs, age 15-39) with cancer may experience disparities in access to health care, compounded by social distancing and stay-at-home orders aimed at reducing the spread of COVID-19. The use of telehealth platforms for clinical visits has accelerated rapidly due to policy changes during the pandemic. Telehealth may provide an avenue for accessing healthcare services among AYAs with cancer; yet, there are few data on AYAs’ preferences and satisfaction relating to telehealth. Our study examined telehealth utilization, satisfaction, preferences and future recommendations among AYAs with a cancer diagnosis. Methods: AYAs in active cancer treatment or in post-treatment survivorship completed an online questionnaire that assessed their experience with telehealth, including: satisfaction with the telehealth visit, likelihood of participating in a future telehealth visit, topics participants would like to discuss via telehealth, and open-ended comments regarding suggestions for improving future telehealth visits. Participants were recruited in two cohorts: a pre-vaccine cohort (September 2020 - January 2021) prior to availability of COVID-19 vaccines in Texas; and, a post-vaccine cohort (April 2021 - May 2021) after vaccine availability. Descriptive statistics were used to summarize preliminary findings. Results: Participants included 273 AYAs with cancer (mean age, 33.8 years old, 26% male, 73% non-Hispanic White, 11% in active treatment, 53% in post-vaccine cohort). Of 71.7% who participated in at least one telehealth visit, 50.9% were somewhat or very satisfied with their visit(s). Topics that all participants preferred to address via telehealth included: stress management (34%); sleep quality (31.7%); diet/nutrition (32.1%); and mental health (29.5%).Topics least preferred for telehealth included fertility counseling (16.7%) and sexual health (13.7%). Open-ended comments from participants highlighted the importance of healthcare providers taking time to listen to their concerns during their visits. Participants suggested that telehealth encounters can be improved by ensuring adequate time for the visit plus good video and audio quality, and using telehealth for follow-up visits rather than initial consultations. Conclusions: About half of AYAs who had participated in a telehealth visit indicated satisfaction with the visit(s). Findings indicated AYAs’ preferences for the types of topics that are most and least preferred to address in telehealth visits, as well as specific recommendations for improving the quality of visits. Consideration of AYAs’ preferences and recommendations in the ongoing implementation of telehealth may help improve patient satisfaction.