Polatuzumab vedotin with dose-adjusted etoposide, cyclophosphamide, doxorubicin, and rituximab (Pola-DA-EPCH-R) for upfront treatment of aggressive B-cell non-Hodgkin lymphomas

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Background: The phase 3 POLARIX trial demonstrated the superiority of polatuzumab vedotin (Pola) over vincristine in the R-CHOP regimen for large B-cell lymphomas. However, it is unknown if Pola can be safely incorporated into intensified regimens typically utilized for the highest risk histologies. To address this question, we conducted a prospective trial (NCT04231877) evaluating Pola with dose adjusted etoposide, cyclophosphamide, doxorubicin, and rituximab (Pola-DA-EPCH-R). Methods: This is a single center, open label, investigator-initiated clinical trial of 6 cycles of Pola-DA-EPCH-R in aggressive large B-cell lymphomas where DA-EPOCH-R is considered standard (eg. HGBCL, PMBCL, and select DLBCL-NOS). Pola is given at 1.8 mg/kg on day 1 without intra-patient dose escalation. All other components of the regimen including escalation of chemotherapy dosing based on neutrophil and platelet nadirs from the previous cycle are given according to Dunleavy et al NEJM 2013. The primary objective is to estimate the safety of Pola-DA-EPCH-R as measured by the rate of dose-limiting toxicities (DLTs) in the first 2 cycles with pre-specified suspension rules if the lower limit of an 80% confidence interval cannot exclude a DLT rate of > 20%. Efficacy, survival, and correlative analyses will also be performed. Results: 18 patients enrolled on study and as of Feb 15, 2022, 3 patients remain on study treatment. Median age was 64 years (range 41-74). With only 3 DLTs, the study met its primary endpoint for safety. Five SAEs were observed, including one grade 5 sepsis/typhlitis (during cycle 1), 3 episodes of febrile neutropenia, and a grade 3 perforation of a colonic diverticula which required a treatment delay of 12 days before completing all expected study therapy. Other grade 3+ non-heme AEs in more than one pt. include hyperglycemia (17%), oral mucositis (17%), incidental asymptomatic pulmonary embolism (17%), abdominal pain (11%), and hypokalemia (11%). Grade 1 peripheral sensory neuropathy was uncommon (22%), no grade 2+ neuropathy was observed. One patient required a decrease in Pola dosing due to a platelet nadir at dose level 1. Among those with at least 2 cycles of treatment, 94% were able to increase chemotherapy to at least dose level 2 (Table). Post cycle 2 interim overall response rate (ORR) and complete response (CR) rate was 88% and 24%, respectively. EOT ORR and CR was 93% and 71%, respectively, with one PD. Updated data will be presented at the meeting. Conclusions: Using Pola at 1.8 mg/kg to replace vincristine in the DA-EPOCH-R regimen appears feasible and met its primary safety endpoint. These data support the further evaluation and use of this approach in histologies where the potential benefit of both an intensified regimen and Pola may be desired. Clinical trial information: NCT04231877. [Table: see text]

Abstract B49: Quantitating circulating tumor DNA in translocation-positive sarcoma patients using CAPP-Seq

A promising tool for noninvasive disease monitoring is analysis of circulating tumor DNA (ctDNA). Healthy individuals carry 1-10 ng/ml of cell-free DNA (cfDNA) in the blood; in oncology patients, ctDNA, which is released from tumor cells, comprises a fraction of the cfDNA and carries tumor-specific alterations, such as mutations, translocations, and copy number alterations. Most ctDNA assays lack robust translocation detection capabilities, since they are designed for adult cancers, which are commonly characterized by mutations and copy number alterations. Even assays that are designed specifically for translocation detection have inherent limitations. They are often PCR-based with laborious methods. First, the patient’s primary tumor sample is sequenced to determine the unique sequence across the translocation breakpoint. This is followed by design of patient-specific primers that can only be used for that individual patient. We sought to design an off-the-shelf, broadly applicable ctDNA assay for translocation detection across pediatric Ewing sarcoma (ES), osteosarcoma (OS), rhabdomyosarcoma (RMS), and synovial sarcoma (SS).

Recent work by our collaborators at Stanford University led to the development of CAncer Personalized Profiling by deep Sequencing (CAPP-Seq), a method capable of ultraspecific and ultrasensitive detection of ctDNA. Utilizing COSMIC and TCGA data, recent sequencing publications defining the landscape of pediatric sarcomas, and our own in-house sequencing data, we designed a pediatric sarcoma CAPP-Seq selector. This selector is comprised of biotinylated oligonucleotides that tile across the introns where translocation breakpoints occur in these pediatric sarcomas. The selector is applied to a sequencing library prepared from patient cfDNA to enrich for the genomic regions of interest via hybrid capture. The resulting enriched library undergoes next-generation sequencing to allow for detection and quantification of circulating tumor DNA.

We have isolated cfDNA from pediatric sarcoma patients and found that their cfDNA levels are higher than levels found in adult oncology patients and healthy individuals, likely due to a large fraction of contributing ctDNA. We have applied our selector to pretreatment plasma samples from 5 EWS patients, 2 OS patients, 4 RMS patients, and 1 SS patient. We detected translocations in 10/12 of these samples. Tumor was available for 7/12 of these patients, and we were able to confirm our plasma results by whole-genome sequencing of the tumor, as a validation of our findings. Additionally, we have applied our selector to serial plasma samples collected over the course of treatment and found that ctDNA levels correlate with clinical status. We have detected translocations at allelic frequencies <0.01%, demonstrating that our method is ultrasensitive and could be used to detect minimal residual disease. Our work demonstrates that CAPP-Seq can serve as an ultrasensitive, broadly applicable tool for circulating tumor translocation detection and offers promise as a method for noninvasive diagnosis and disease monitoring.

Citation Format: Avanthi Tayi Shah, Tej D. Azad, Jake J. Chabon, Marcus Breese, Bogdan Tanasa, Aviv Spillinger, Stanley G. Leung, Maximilian Diehn, Ash A. Alizadeh, E. Alejandro Sweet-Cordero. Quantitating circulating tumor DNA in translocation-positive sarcoma patients using CAPP-Seq [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr B49.