A 3D RANGE MODULATOR FOR ULTRA-SHORT PROTON FLASH IRRADIATION

Background and aims In the pursuit of optimal parameters for FLASH irradiation, all components involved in the beam delivery should be compatible with requirements spread in an extreme and wide unexplored regime. Aiming for minimal total irradiation times with modulated proton beams, which deliver a flat depth-dose distribution along tumors, a static range modulator has been developed to accommodate ultra-short beam durations regardless of their time structure. The design goals were set to match the functionality of the rotating wheel used for in-vivo and in-vitro FLASH investigations at HZB. Methods Having the form of a ridge filter extended to an additional dimension, a hexagonal-pyramid pattern was configured to an incoming beam of 23 MeV energy with > 1 mm radius, in order to create a 6 mm uniform field with a flat dose range of 5 mm at the target. The manufacturing was done with a 3D printer using VeroWhite, a material similar to PMMA. The lateral and distal dose distribution of both modulators were measured using a Markus Chamber (PTW-Freiburg, Germany) in a water phantom and a radioluminescent screen mounted in front of CCD camera, respectively. Results The developed modulator created very flat dose distributions as designed, with negligible differences to the reference rotating wheel. The positioning tolerances were evaluated as relatively relaxed, with offsets of 2 cm and an angle of 5 degrees not compromising the desired performance. Conclusions The developed static modulator allows systematic proton FLASH studies on small organs using a broad range of timing schemes, disentangled from temporal and spatial incoherencies.

355 Pembrolizumab and bevacizumab in platinum resistant epithelial ovarian cancer patients

BackgroundThere is a medical need in platinum resistant ovarian cancer patients. Median progression-free survival (PFS) is 3.4 months with chemotherapy and 6.7 months with chemotherapy-bevacizumab combination regimens.1 RECIST overall response rate (ORR) is 11.8% and 27.3%, respectively. The ORR is 15.9% for bevacizumab as a monotherapy with a median PFS of 4.4 months.2MethodsNCT03596281 An open-label phase 1b trial with a modified toxicity probability interval design to evaluate the combination of a flat dose of 400mg bevacizumab for 6 cycles and 200mg pembrolizumab until disease progression, unacceptable toxicity or completed 24 months of treatment in patients with platinum resistant ovarian cancer. The primary evaluation criteria is safety, the secondary endpoint is the efficacy.Results19 patients have been enrolled between January 2019 and February 2021 in 6 French centers. Patients‘ characteristics are reported (table 1). No dose limiting toxicities were observed. Grade 3 treatment related adverse events occurred in 3 patients (i.e. arterial thromboembolism, bowel perforation, proteinuria and sepsis). No grade 4/5 toxicities were induced. A median of 7 cycles (range 3–14) were administered. Median follow-up of patients was 4.1 months (1.8–23). The RECIST ORR was 26.3% (1 complete response and 4 partial responses) (table 2). The disease control rate was 78.9%. The time to progression was not yet reached in 6 patients. The ORR was equivalent whether patients have been pretreated or not with bevacizumab (27.3 and 25% respectively) (table 3). The ORR according to the combined positive score (CPS) for the evaluation of PD-L1 was 50.0% for CPS≥10% (n=4), 30.0% for a CPS≥1% (n=10) and 25.0% for CPS<1 (n=8) (table 4).ConclusionsA chemotherapy-free regimen combining pembrolizumab and bevacizumab was well tolerated and showed encouraging results in heavily pretreated platinum resistant ovarian cancer patients independent of their previous challenge with antiangiogenic agents.AcknowledgementsFunding for this research was provided by Fondation Cancer du Luxembourg and Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.Trial RegistrationNCT03596281ReferencesPujade-Lauraine E, et al. Bevacizumab combined with chemotherapy for platinum-resistant recurrent ovarian cancer: The AURELIA open-label randomized phase III trial. J Clin Onco Off J Am Soc Clin Oncol 32,1302–1308 (2014).Cannistra SA, et al. Phase II study of bevacizumab in patients with platinum-resistant ovarian cancer or peritoneal serous cancer. J Clin Oncol Off J Am Soc Clin Oncol 33,5180–5186 (2007).Ethics ApprovalThis study was approved by CPP Sud Méditerranée V institution’s Ethics Board; approval number 18.020 (EudraCT number 2017-004197-34).ConsentWritten informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.

958 BNT211: a phase I/II trial to evaluate safety and efficacy of CLDN6 CAR-T cells and vaccine-mediated in vivo expansion in patients with CLDN6-positive advanced solid tumors

BackgroundBNT211 is a chimeric antigen receptor (CAR)-T cell product candidate that targets the tumor specific antigen Claudin-6 (CLDN6). Preclinical studies demonstrated that combining these engineered cells with a CAR-T cell Amplifying RNA Vaccine (CARVac) leads to in vivo expansion of adoptively transferred CAR-T cells, resulting in their improved persistence and functionality.MethodsThis first-in-human, open label, multi-center trial involves a bifurcated 3+3 design with separate CLDN6 CAR-T cell dose escalations (single flat-dose) for monotherapy (part 1) and the combination with CARVac (part 2) based on 3 dose levels (DL). In part 2, CARVac is applied every 3 weeks starting at day 4 post transplantation including a one-step intra-patient dose escalation. Patients with CLDN6-positive relapsed or refractory solid tumors without further standard treatment options and ECOG 0 or 1 are eligible for recruitment.ResultsAs of July 23rd 2021, 8 patients have been treated. DL1 of part 1 has been completed, while dosing of part 1 DL2 and part 2 DL1 is ongoing. One patient with cancer of unknown primary was treated with a dose below DL1 in combination with CARVac; the underlying diseases of the other 7 treated patients were testicular, ovarian and endometrial cancer as well as soft-tissue sarcoma. No acute or dose-limiting toxicities and no serious adverse events related to the drug product have been reported. Manageable cytokine release syndrome (CRS, grade 1-2, the latter managed with Tocilizumab) without any signs of neurotoxicity have been observed in both patients of part 1 DL2. Only transient and moderate elevations of IL-6 and CRP serum levels occurred in remaining patients. Notably, administration of CARVac resulted in transient flu-like symptoms resolving within 24h. Analysis of CAR-T cell frequency in peripheral blood revealed robust engraftment followed by decline after day 17. Further expansion was noted in two patients with liver metastases accompanied by elevated levels of ALT, AST and AP, while total bilirubin was not affected. First tumor assessment 6 weeks after transplantation available for 5/8 patients revealed 4 SD (3 transitioned into PD after an additional 6-18 weeks) and 1 PD. Strikingly, three patients showed initial tumor shrinkage according to RECIST1.1 (reduction of target sum: -18%, -21% and -27%).ConclusionsCLDN6 CAR-T cells +/- CARVac show a favorable safety profile at doses tested and encouraging signs of efficacy. Updated data from open cohorts and especially for combination with CARVac will be presented.AcknowledgementsBNT211-01 is funded by BioNTech Cell & Gene Therapies GmbH.Trial RegistrationClinicaltrialsgov: NCT04503278ReferencesN/A Ethics ApprovalEthics & Institutional Review Board approvals were obtained from the respective participating countries prior to initiation of the trial.ConsentN/A

Oral Nifedipine versus Intravenous Labetalol for Acute Blood Pressure Control in Severe Hypertension of Pregnancy: A Study at Faridpur Medical College Hospital

The first line antihypertensive treatment for severe hypertension of pregnancy includes labetalol, hydralazine, or nifedipine. Rapid but safe blood pressure control allows the definitive treatment, the delivery of baby to be carried out with minimal delay and good maternal and fetal outcomes. This non-randomized clinical trial was performed in Faridpur Medical College Hospital to compare the effectiveness and tolerability of oral nifedipine and intravenous labetalol in the acute control of severe hypertension of pregnancy. Total 50 admitted pregnant women with a viable fetus (>_ 24 weeks of gestation) having severe hypertension were allocated into two groups, Group A: 25 patients receiving oral nifedipine (10 mg), Group B: 25 patients receiving injectable labetalol (with incremental doses: 20, 40, 80mg). Up to 5 doses were tried for each drug at 15 minutes interval until target blood pressure (<_150/100 mmHg) was achieved. Baseline characteristics like mean age, mean weight, heart rate, systolic and diastolic pressures were similar in both labetalol and nifedipine groups. The average time required to achieve target blood pressure was 30.33 ± 10.44 minutes for labetalol and 25.63 ± 10.12 minutes for nifedipine (p=0.9129). Feto-maternal outcomes and adverse drug related effects were similar among the two groups. Both intravenous labetalol and oral nifedipine were found to be equally effective and well tolerated. Nifedipine may be preferable as it is a simple, flat dose schedule and an oral regimen. Faridpur Med. Coll. J. 2021;16(1):25-29

Pembrolizumab in combination with bevacizumab and pegylated liposomal doxorubicin in patients with platinum-resistant epithelial ovarian cancer.

5522 Background: There is a medical unmet need for effective treatments in platinum resistant ovarian cancer patients. We assessed the safety and efficacy of a combination of pembrolizumab with bevacizumab and pegylated liposomal doxorubicin (PLD). Methods: This is an open-label phase 1b trial in patients ECOG 0 or 1 with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer. The safety of the dual combinations of pembrolizumab with bevacizumab or with PLD were previously evaluated in 6 patients respectively. In the absence of dose limiting toxicities (DLT) the triple combination was evaluated at a maximum tolerated dose (MTD)-1 for PLD in 3 patients and in the absence of DLT at MTD. The sample size was calculated according to the modified toxicity probability interval design. The primary evaluation criteria was the safety, the secondary endpoint was the outcome. Pharmacokinetics of the flat dose of bevacizumab will be evaluated. Results: 22 patients were enrolled from September 2019 until June 2020 in six French centers. 3 initial patients have been treated at 20mg/m2 of PLD (MTD-1) and 19 patients were treated at the dose of 30mg/m2 of PLD (MTD) combined with 200mg of pembrolizumab until progression, unacceptable toxicity, or withdrawal of consent and 400mg of bevacizumab for a total of six cycles. The patients’ characteristics are reported in the table. No DLT occurred. Grade 3 palmar-plantar erythrodysesthesia were reported in 4 patients. The recommended phase II dose of PLD was 30mg/m2 in combination with pembrolizumab and bevacizumab. For patients treated at MTD, the overall response rate was 32% (6 partial responses) with 74% of clinical benefit with a durable response in 10 patients (53%). Median number of cycles was 7.5 (2 to not reached). Two patients are still on treatment. Correlative studies are ongoing. Conclusions: The combination was well tolerated and demonstrated clinical benefit in 74% platinum resistant ovarian cancer patients with durable response (>6 months) in 53% of patients. Clinical trial information: NCT03596281. [Table: see text]

Stool microbiota profiling of patients with muscle invasive bladder cancer receiving neoadjuvant pembrolizumab.

4533 Background: Immune checkpoint inhibitors (ICIs) showed efficacy in metastatic urothelial carcinoma (UC) and promising activity in muscle-invasive and non-muscle invasive UC of the bladder. Recent studies revealed the immunomodulatory effect of the gut microbiota on ICIs efficacy across several malignancies, identifying microbial “signatures” associated with response to therapy and effective antitumoral T-cell activity. In our study, we aimed to study the stool microbiota in patients undergoing neoadjuvant immunotherapy (IO) for muscle-invasive UC. Methods: Pre-IO stools were available for analysis from 42 patients enrolled in the PURE-01 trial (NCT02736266), testing 3x200mg flat-dose pembrolizumab every 21 days before radical cystectomy (RC). All samples were collected using Stool Nucleic Acid Collection and Preservation Tubes (Norgen) and extracted using the Stool DNA Isolation Kit (Norgen), according to the manufacturer’s protocol. 16s sequencing was performed using standardized protocols at the internal facility, using mock communities and DNA standards (ZymoBIOMICS) to control for extraction and sequencing contaminations. A QIIME-based bioinformatic pipeline was used for microbiome analyses. Complete response (CR) to neoadjuvant IO was defined as ypT0N0 at pathologic examination on radical cystectomy specimens, while partial response (PR) was defined as < ypT2N0. Concomitant antibiotic therapy (ABT) was defined as any ATB between 30 days prior to the first pembrolizumab dose and the planned RC. Results: In our study sample, 23 patients responded to IO (21 CR + 2 PR). Overall median age was 68.5 years. Among responders, 20 (87%) patients had a smoking history (vs. 15 (79%) in non-responders) and 4 (17%) underwent concomitant ABT (vs. 6 (32%) in non-responders). Alpha-diversity assessed by richness (ACE index) was higher in responders vs. non-responders (p = 0.05), while no significant diversity was found. Beta-diversity did not show clear clustering of responders vs. non-responders. LEfSe identified 16 bacterial taxa with a linear discriminant analysis (LDA) score ≥2.5 that were differently enriched between responders and non-responders. Among them, we identified the genus Sutterella enriched in responders (p = 0.02), while the species Ruminococcus bromii was enriched in non-responders (p = 0.02). Conclusions: Our analyses showed an association between response to neoadjuvant-IO and microbiome composition in an intention-to-cure population with muscle invasive UC. We found bacterial taxa specifically enriched in responders or non-responders using pre-therapy stool specimens. The identified taxa may be tested in future studies as potential indicators of therapy outcomes, alone or in combination with other IO biomarkers. These results may also inspire new strategies of gut microbiota modulation to promote response in immunotherapy-refractory patients.

Ipilimumab, nivolumab and tocilizumab as first-line therapy for advanced melanoma.

TPS9589 Background: Interleukin 6 (IL-6) functions in the maintenance of hepatocytes, haemotopoietic progenitor cells, a variety of other tissues, and regulates the innate and adaptive immune system. IL-6 may play a role as a chronic inflammatory mediator in altering levels of acute phase proteins synthesized by the liver and circulating myeloid cells which have been shown to be associated with short survival with checkpoint inhibition and which are immune suppressive. The immunomodulatory properties of interleukin-6 may in part also be responsible for immune related adverse events, given the reversal of those toxicities observed with IL-6 receptor blockade in clinical practice. To assess if blockade of IL-6 binding is associated with a decrease in irAEs and/or an increase in efficacy defined as overall response rate (ORR) at week 24 in patients receiving ICB, we added tocilizumab to ipilimumab and nivolumab therapy. Methods: The current phase II trial is a two-stage design to assess the safety, tolerability, and grades 3-5 immune related toxicities of tocilizumab administered every 6 weeks up to week 24 in combination with ipilimumab at 1 mg/kg and nivolumab at 3 mg/kg every 3 weeks for 4 doses each during a 12 week induction period, then administered every 6 weeks with nivolumab at 240 mg flat dose every 2 weeks in maintenance for up to 24 weeks, and nivolumab alone will be given at 480 mg flat dose every 4 weeks thereafter for up to 2 years. Eligible patients include those age 18 or older with measurable and unresectable stages III/IV melanoma (cutaneous, acral, mucosal), without prior systemic treatment for metastatic disease. Adjuvant therapy (IFN-alpha, ipilimumab and/or nivolumab, or pembrolizumab) is allowed. Patients with metastatic melanoma of brain are allowed, if neurologically stable and off immunosuppressive steroids. A total of 18 patients will be treated in the first stage, and 49 additional patients in the second stage for a total of 67. The comparator data are from the N3I1 arm of Checkmate-511 trial, in which treatment-related grades 3-5 irAEs were 33.9% with a 45.6% response rate (1). Prespecified activity goal for the first stage of accrual has been met; second stage accrual began in January 2021. References: (1) Lebbé C, Meyer N, Mortier L, Marquez-Rodas I, et al. Evaluation of Two Dosing Regimens for Nivolumab in Combination With Ipilimumab in Patients With Advanced Melanoma: Results From the Phase IIIb/IV CheckMate 511 Trial. Journal of Clinical Oncology 2019 37:11, 867-875. Clinical trial information: NCT03999749.

Phase II evaluation of the triple combination of PDS0101, M9241, and bintrafusp alfa in patients with HPV 16 positive malignancies.

2501 Background: There are more than 630,000 cases of HPV associated malignancies including cervical, oropharyngeal and anal cancer worldwide annually. HPV 16 is responsible for the majority of these cases. About 15-20% of HPV associated malignancies respond to PD-(L)1 inhibitors, but for the overwhelming majority of patients who progress on these immunotherapies there is no effective standard of care therapy. Preclinical studies have shown that the triple combination of PDS0101 (Versamune-HPV), a liposomal multipeptide therapeutic vaccine targeting HPV 16 E6/E7, M9241, a tumor-targeting immunocytokine composed of IL-12 heterodimers fused to a monoclonal antibody targeting free DNA in necrotic tumor regions, and bintrafusp alfa, a bifunctional fusion protein targeting TGF-β and PD-L1, resulted in maximum HPV-specific T cell responses, T cell tumor infiltration and tumor reduction as compared to any one or two of these agents alone. Methods: Fourteen pts with HPV 16+ relapsed or refractory advanced cancer were enrolled to the triple combination of PDS0101, M9241 and bintrafusp alfa (NCT04287868). Pts received bintrafusp alfa at 1200 mg flat dose i.v. every 2 weeks, M9241 at 16.8 mcg/kg s.c. every 4 weeks and PDS0101 given as two separate 0.5 ml s.c. injections every 4 weeks. Dose reductions of M9241 to 8 mcg/kg were allowed as well as skipped doses of any agent for ongoing toxicities. Results: Fourteen pts with advanced HPV 16+ cancers (5 cervical, 2 vaginal/vulvar, 4 anal, 3 oropharyngeal) were treated. 4/14 (28.6%) pts had a grade 3 treatment related toxicity including grade 3 hematuria in 2 pts with cervical ca and prior pelvic radiation and grade 3 AST/ALT elevation in 2 pts, one with anal ca and one with vaginal ca. For one patient with grade 3 AST/ALT elevation dose reduction of M9241 from 16.8 to 8 mcg/kg allowed for continued treatment with AST/ALT remaining at grade 1 or less. One additional patient had transient asymptomatic grade 4 neutropenia. No other treatment related grade 3 or greater toxicities were noted. 10/14 (71%) pts have had objective responses: 1 CR (anal ca) and 9 PRs (3 cervical, 2 vulvar/vaginal, 2 anal, 2 oropharyngeal) with 9/10 of these responses ongoing after a median 5 month of follow up. Of the 14 pts, 6 pts have checkpoint naïve disease and 8 pts have checkpoint refractory disease. 5/6 (83%) pts with checkpoint naïve disease and 5/8 (63%) pts with checkpoint refractory disease have had objective responses. Analyses of immune responses and other immune correlates are ongoing. Conclusions: Triple combination of PDS0101, M9241 and bintrafusp alfa appears to have a manageable safety profile along with early evidence of notable clinical activity for pts with both checkpoint naïve as well as checkpoint refractory HPV 16+ advanced malignancies. Clinical trial information: NCT04287868.

Molecular Modifications of the Pseudomonas Quinolone Signal in the Intermicrobial Competition with Aspergillus

The Pseudomonas quinolone signal (PQS) is an important quorum-sensing molecule for Pseudomonas aeruginosa that regulates virulence factors, chelates iron, and is an important factor in interactions with eukaryotes, including fungi and mammalian hosts. It was previously shown to inhibit or boost Aspergillus, depending on the milieu iron concentration. We studied several molecular modifications of the PQS molecule, and their effects on Aspergillus biofilm metabolism and growth in vitro, and the effects of iron supplementation. We found that most molecules inhibited Aspergillus at concentrations similar to that of PQS, but with relatively flat dose-responses, and all were less potent than PQS. The inhibition was reversible by iron, suggesting interference with fungal iron metabolism. Stimulation of Aspergillus was not noted. We conclude that the critical Aspergillus-inhibiting moeities of the PQS molecule were partially, but not completely, interfered with by molecular modifications at several sites on the PQS molecule. The mechanism, as with PQS, appears to relate to fungal iron metabolism.