{'fraction_non_alphanumeric': 0.043711495746196725, 'fraction_numerical': 0.027576379866728135, 'mean_word_length': 4.921091811414392, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
All-Oral Low-Dose Chemotherapy TEPIP is Effective and Well-Tolerated in Relapsed/Refractory Patients With Aggressive B-Cell Lymphoma

Purpose Treatment options in patients (pts.) with advanced relapsed and refractory aggressive B-cell lymphoma are limited. Palliative all-oral chemotherapy regimens reduce in-patient visits and contribute to quality of life. The all-oral low-dose chemotherapy regimen TEPIP comprises the conventional chemotherapy agents trofosfamide, etoposide, procarbazine, idarubicin and prednisolone. Methods Safety and efficacy of TEPIP was evaluated in an observational retrospective, single-center study at the University Medical Center Regensburg between 2010 and 2020. Treatment with TEPIP was applied for 7 or 10 days during a 28-days period. In a subgroup of fit and therapy-motivated pts. rituximab was added. End points were overall survival (OS) and progression free survival (PFS). Adverse events ≥ CTCAE grade III were reported. Results 35 highly pre-treated pts. with aggressive B-cell lymphoma were enrolled. Median age at TEPIP start was 67 years and 85% of pts. received TEPIP as ≥ third treatment line. Overall response rate (ORR) was 23% (CR 17%). Pts. benefited from additional rituximab administration (ORR 67%) and a lower number of pre-treatments (ORR 41%). The OS was 3.3 months (m) with a 1y-OS of 25.7% and the PFS amounted to 1.3 m with a 1y-PFS of 8.8%. OS and PFS were significantly prolonged in pts. that responded to treatment or additionally received rituximab. Adverse events were mainly hematological and occurred in 49% of pts. Conclusion TEPIP was well-tolerated and induced respectable response in a difficult-to-treat patient cohort. In particular, the all-oral administration enables out-patient use with palliative intent.


INTRODUCTION
The aggressive diffuse large B cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL) in the Western hemisphere with an incidence of 7 cases per 100,000 people (1-3) accounting for 2.8% of all cancer diagnoses worldwide (4).
While the majority of patients achieves durable and complete remission with first-line treatment (5-7), 40% do not respond or experience relapse (R/R DLBCL), most frequently within the first 2 years (8) but also later (9). Eligibility for second-line options strongly depends on the patient's performance status and age as potentially curative standard second-line regimens comprise salvage chemotherapy followed by consolidation with high dose chemotherapy (HDT) and autologous stem cell transplantation (ASCT) (10). To undergo ASCT, a complete (CR) or at least partial remission (PR) from a previous salvage regimen is favorable, but may be only achieved in up to 60% of patients resulting in a transplantation rate of 50% (11)(12)(13). Patients failing to respond to first salvage therapy or relapsing after ASCT have a poor prognosis. However, long-term survival may be achieved by switching salvage therapy to enable subsequent ASCT (14) or by proceeding to a reduced intensity conditioning (RIC) and allogeneic transplantation (alloTx) (15).
Due to insufficient response to chemotherapy, comorbidities, and age, a substantial proportion of patients is not eligible for HDT and transplantation. During the last years, substantial progress has been made in the development of novel approaches for relapsed/refractory disease including CD19 CAR T-cells. CAR T-cell therapies achieve impressive objective response rates (ORR) of up to 74% in heavily pre-treated patients of all ages but are associated with high costs and potentially lethal adverse events such as neurotoxicity, cytokine release and protracted immunodeficiency (16)(17)(18)(19). Contraindications to and relapse after CAR T-cell therapy or alloTx strongly limit the probability of a sustained response (20). In this context, about 50% of patients develop a relapse of DLBCL after CAR Tcell therapy representing a big therapeutic challenge (21,22). In these palliative situations, therapies must focus on symptom control as well as prolongation and quality of life.
In contrast to conventional chemotherapies aiming for a maximal tolerated dose (MTD), metronomic regimens combine regularly administered, low-dose agents to reduce toxicity and overcome acquired resistance while equally targeting tumor cells and the tumor-promoting microenvironment (32)(33)(34)(35)(36). Until today, only few groups have focused on metronomic regimens in relapsed and refractory lymphoma, however with partially impressive results (37)(38)(39). In sum, these insights underline the urgent need for further development of well-tolerated out-patient treatment options for CAR therapy and transplantation ineligible or relapsed patients with R/R DLBCL to improve palliation.
In this retrospective, single-center study we demonstrate efficacy and safety data of an all-oral, prolonged low-dose chemotherapy regimen TEPIP (trofosfamide, etoposide, procarbazine, idarubicin, prednisolone), which was developed and administered at the University Hospital Regensburg. TEPIP is also given at doses below MTD with the goal to exert alternative antitumor effects while minimizing side effects. However, due to the rather prolonged interval breaks, this regimen (given 7 or 10 days of a 28-day cycle) does not fulfill the strict definition of a metronomic schedule.

METHODS
In this single-center study we retrospectively analyzed safety and efficacy of an all-oral chemotherapy, TEPIP, administered in 35 patients at the University Medical Center Regensburg (UKR) between 2010/01/01 and 2020/12/31. The cohort was identified by an in-clinic, medical file database query using the terms "TEPIP" and "R-TEPIP" and only aggressive B cell lymphomas were considered. All data (histologic diagnoses, clinical parameters, outcome measures) were obtained from medical reports. Due to the retrospective nature of this study and the out-patient drug administration, the data set is partially limited. The analysis was approved by the local Ethics Committee (reference number: 20-1901-104) and performed in compliance with the current Helsinki Declaration. All patients alive gave written informed consent for publication.

Disease Classification
The underlying disease was defined as primary in patients with only aggressive B-cell lymphoma (DLBCL, EBV+, prolymphocytic/ lymphoblastic). In contrast, the disease was termed non-primary, if transformed from a previous indolent lymphoma or concurrently showing aggressive and indolent histology. Lymphoma disease was staged before TEPIP start according to the Ann Arbor criteria and prognosis was assessed at first diagnosis by use of the international prognostic index (IPI) score. In cases without a reported IPI score, appropriate parameters (LDH, age, performance status, extranodal manifestations, stage) were collected to raise a definitive or in cases of incomplete data sets an "at least" IPI score in every patient. Only extranodal manifestations of the aggressive, but not of possibly concurrent indolent lymphoma were considered in the calculation of the IPI score.

Chemotherapy Regimen
TEPIP was administered as an all-oral low-dose chemotherapy regimen allowing a full out-patient treatment. TEPIP comprises trofosfamide 150 mg (3 single doses of 50 mg), etoposide 50 mg (one single dose), procarbazine 100 mg (one single dose) and prednisolone 100 mg (one single dose) or dexamethasone 16 mg (2 single doses of 8 mg) at days 1 to 10 of 28, which was shortened to 7 days in case of numerous pre-treatments as necessary in most of the patients. On days 8 to 10 (10-day course) and 5 to 7 (7-day course), respectively, a daily single dose of idarubicin 10 mg was added ( Figure 1). Dose reductions due to adverse events were performed according to physician´s choice. Recommendations for dose reductions included limiting trofosfamide to two or one dose of 50 mg per day, procarbazine to 50 mg per day or etoposide to 50 mg every other day. 9 patients additionally received the monoclonal anti-CD20 antibody rituximab (375 mg/m² intravenously, iv) on day 1 of each course ( Figure 1). The course was repeated each 28 days provided that the leukocyte count exceeded 3000 per microliter and continued until disease progression or intolerability due to toxicity. Apart from an appropriate antiemesis (e.g., metoclopramide) no specific supportive therapy (e.g., granulocyte-colony-stimulating factor) was administered.

Response Assessment
Response was reported as the best response documented by medical reports. In patients providing available CT or PET-CT imaging, response was assessed according to the 2014 Lugano criteria (40)and the recommended staging schedule was eight weeks. The objective response rate (ORR) was defined as the sum of patients acquiring complete or partial remission. Survival was analyzed as overall survival (OS) covering the period between onset of TEPIP treatment and the patient´s death or end of the observation period (2020/12/31), respectively, and progression free survival (PFS) representing the period between treatment start and diagnosis of disease progression or death due to any reason.

Adverse Event Assessment
Toxicities are listed as reported by out-patient reports and graded according to the Common Toxicity Criteria for Adverse Events (CTCAE) version 5.0, with only adverse events of CTCAE ≥ grade III being reported in this analysis.

Statistics
Analyses are performed by PRISM 9 (GraphPad, San Diego, CA, USA) and SPSS 28 (IBM, Armonk, NY, USA). The endpoints of the study are OS and PFS which are depicted as Kaplan-Meier curves. Differences between subgroups are determined by the Fisher´s exact test (ORR) and Mantel-Cox log-rank test (OS and PFS). Additionally, the log-rank Hazard Ratio (HR) is reported. Data are judged to be statistically significant when p < 0.05.

Outcome and Survival Analysis
The median follow-up was 3.3 months (range 0.9 -80.3) and at the time of analysis 33 patients had died (94%).
Therapy was discontinued due to disease progression (26/35), reduced performance status (2/35) and infectious adverse events (2/35). Of note, 5/35 patients discontinued treatment with complete remission, of which 2/5 patients received 2 and 3 courses of TEPIP, respectively, after best response, whereas in 3/5 patients the treatment was stopped immediately at diagnosis of CR. In addition, 3/5 patients received one or two courses of rituximab for maintenance therapy after complete remission and TEPIP discontinuation. Relapse in patients who discontinued TEPIP with CR occurred after a median time of 7.2 months (range: 1.5 -54.1 months). Besides, in one patient treatment was interrupted with complete remission, started again 3 months later when relapse occurred and finished with progressive disease after initial response within 5 further courses. Subsequent next line chemotherapy was initiated in 14/35, and radiation in 3/35 patients, whereas 15/35 patients did not receive any further treatment (no report 3 pts.). Overall survival (OS) was assessable in all patients, whereas the date of progression lacked in one patient due to the outpatient setting. Median OS (mOS) was 3.3 months (Figure 2A) with a one-and two-year OS rate of 25.7% (95% CI: 12.8-40.8) and 13.1% (95% CI: 4.3-26.8), respectively. The median PFS (mPFS) amounted to 1.3 months ( Figure 2B) with a one-year PFS rate of 8.8% (95% CI: 2.3-21.1). Remarkable 12.5 months mOS and 3.8 months mPFS were observed in 16 patients who received at least 2 TEPIP courses.
Further, the older half of patients being ≥ 67 years had a significantly longer OS (median 5.6 vs. 2.3 months) but not PFS (median 2.0 vs. 1.0; p.069) (Figures 3A, B). OS and PFS were significantly longer in patients treated with a combination of rituximab + TEPIP (median 14.9 vs. 1.6 months) ( Figures 3C, D) . In responding patients (CR or PR), median duration of treatment was 4.5 months (range: 2.0 -21.9) and only 2 patients subsequently developed disease progression under TEPIP treatment, whereas 5 patients finished treatment without evidence of residual disease (no report: 1 pt.). The median OS and PFS in this cohort were 22.6 (1y-OS 7/8 pts.; 2y-OS 3/8 pts.) and 11.2 months (1y-PFS 3/7 pts.; 2y-PFS 1/7 pts.), respectively ( Figures 3E, F). Of note, in 6 patients reaching a CR the median OS was 37.6 months with an estimated 1and 2-year OS of 6/6 and 3/6 pts. and 1-and 2-year PFS of 3/6 and 1/6 pts., which stands in contrast to the median OS and PFS of 2.3 and 1.0 months in patients not responding to the TEPIP treatment.
No significantly longer OS and PFS were seen in patients with a low(-intermediate) IPI score at first diagnosis and TEPIP start, an objective response to prior treatment, a limited stage at TEPIP start (Ann Arbor I/II) and a primary lymphoma ontogeny.
Patients with less than 3 prior treatment lines had a numerically, but not significantly improved OS of 5.5 months (median 5.5 vs. 2.5 months, p.662). A detailed synopsis of the outcome and survival analysis is shown in Table 2.

Safety Analysis
Since all patients received TEPIP on an out-patient basis, analysis of treatment-related adverse events was limited. To the best of our knowledge, 17/35 patients (49%) developed in total 30 adverse events ≥ CTCAE grade III, whereas no events were reported in 16/35 patients (46%, no report: 2 pts., Table 3). Grade IV toxicities only occurred in hematologic adverse events (4 pts. with grade IV neutropenia/leukopenia, 2 pts. with grade IV thrombopenia). Of note, the proportion of elderly patients (≥67 years) who noticed a side effect was equal to the subgroup of younger patients (9/18, 50%). The most frequently observed events (17/35) were hematologic findings with leukopenia/ neutropenia in 8 patients, anemia in 6 patients and thrombopenia in 3 patients (Table 3). Unfortunately, there are no reliable data on the use of G-CSF and erythrocyte or platelet concentrates. Infectious complications occurred in 6/35 patients with two patients suffering from pneumonia, one patient from fever of unknown origin and one patient of urinary tract infection. Two patients were hospitalized with a septic event, of whom one subsequently died ( Table 3). Therapy was discontinued due to infectious adverse events only in 2 patients. Gastrointestinal complications were reported in 5 patients with nausea and diarrhea in two and intestinal hemorrhage in two patients. Of note, one patient experienced a not lethal intestinal perforation, possibly caused be a preliminary mesenterial lymphoma manifestation. Rare adverse events observed each in one patient were pulmonary embolism and an epileptic seizure ( Table 3). One patient died of a massive oropharyngeal tumor bleeding after the first chemo course, which was, however, not considered therapy-related.   (42)(43)(44)(45), etoposide (37)(38)(39)46), procarbazine (37,47), idarubicin (48,49)]. In our heavily pretreated patient population having received a median of 3 prior lines, we observed an ORR of 23% (17% CR). Median survival was 3.3 months with 26% of patients surviving the first year and 9% remaining progression free during this period. Larger prospective (randomized) trials investigating a similar patient population showed comparable response rates. Pettengell et al. reported a complete response rate of 20% for pixantrone treatment vs. 5.7% for comparator chemotherapy as salvage therapy in patients with aggressive lymphoma and a median of 3 previous therapy lines (50). By minimizing the number of patient visits all-oral therapies contribute to quality of life. In this context, several trials have investigated the use of orally administered lenalidomide (25 mg on days 1-21 of 28-day cycles) in heavily pre-treated patients suffering from DLBCL. The NHL-002 and NHL-003 trials showed ORR rates of 19 and28% with CR rates (including CR unconfirmed) of 12 and 7% (51,52). Taking into account that in the TEPIP cohort only 3 patients (9%) ( Table 1) had an objective response to the directly preceding therapy, the ORR of 23% (17% CR) is even more notable. Moreover, with the tight median TEPIP treatment duration of 1.3 months it must be noted, that the intention to treat was highly palliative in a large proportion of patients. Consistently, 16 patients who received at least two courses of TEPIP had significantly improved median OS and PFS of 12.5  and 3.8 months, respectively, and an ORR of 50% (CR 38%). Additional administration of rituximab to the regimen in 9 fit and treatment-motivated patients resulted in a further improved ORR of 67% with prolonged OS (14.9 months) and PFS (5.6 months), however requiring in-patient treatment. Of note, in patients responding to treatment (CR or PR) OS and PFS was significantly prolonged, which highlights the potential for a sustained treatment effect. Interestingly, despite its relevance to good prognosis (53,54), low and low-intermediate IPI score did not result in better ORR, OS, and PFS at either initial diagnosis or TEPIP initiation. Patient age over 60 years contributes to the IPI score and is a risk factor for poor prognosis in DLBCL (53,54). Besides a decreased treatment tolerance due to comorbidities, also alterations in drug metabolism and impaired bone-marrow capacity may preclude the administration of intensive (salvage) chemotherapy in the elderly and frail (55)(56)(57). The TEPIP cohort had a median age of 67 years, indicating a vulnerable patient population. Nevertheless, also elderly patients (≥67 years) benefited from TEPIP treatment in terms of median OS (5.6 months) and PFS (2.0 months). However, it should be noted that in patients ≥67 years the regimen was started earlier in treatment (median 2 vs. 3 prior lines), administered in a higher number of courses (median 1.5 vs. 1), and more frequently combined with rituximab (6 vs. 3 pts.).
Treatment-emergent adverse events CTCAE grade III or higher occurred in every second patient and were predominantly hematologic (49%). This could be at least partially explained by an assumable reduction of the bone marrow capacity in our highly pre-treated cohort. However, recommendations for doseadjustment apparently prevented the translation of cytopenia into non-hematologic events, as only 17% of patients developed infections and 6% of patients had bleeding complications ≥ CTCAE grade III. Remarkably, only in 2 patients the treatment was discontinued due to infectious complications. As doseadjustment was performed according to the physician´s choice, reliable numeric statements are not available. Older patients did not experience a higher number of adverse events ≥ CTCAE grade III (50%). Due to retrospectivity and the out-patient setting additional unreported events cannot be completely excluded. However, compared with previous palliative regimens in R/R DLBCL patients (24,29,38,50,58) and given the seniority of the multiply pretreated cohort, the safety profile of TEPIP is tolerable and manageable. For instance, a phase 3 trial treating a similar patient population with pixantrone vs. comparator chemotherapy showed grade 3 or 4 toxicity in 76.5%vs 52.2% with neutropenia being the predominant event (50).
Several novel strategies, including CAR-T cells (16,17), bispecific (28) and further antibodies [tafasitamab (58), polatuzumab-vedotin (27)] have achieved impressive and sustained responses in the challenging subset of R/R DLBCL patients. Nevertheless, the use of these state-of-the-art therapies is limited due to patient comorbidities, but also in the global context due to high costs and availability. In addition, most novel drugs are administered intravenously and require close monitoring of side effects or hospitalization. However especially in advanced palliative settings, all-oral therapies are sought to prolong survival while maximizing quality of life. Besides, our oral low-dose regimen TEPIP was developed to provide a decentralized therapy concept for rural areas such as eastern Bavaria.
To date, few studies have evaluated the safety and efficacy of such-like therapies in DLBCL. Coleman et al. reported a well-tolerated, metronomically applied low-dose regimen PEP-C, that achieved remarkable overall response rates of 69%, albeit predominantly in indolent lymphoma (37). Another all-oral metronomic combination of cyclophosphamide, etoposide and prednisolone used in aggressive lymphoma yielded comparable response rates to TEPIP (CR 19.4 vs. 17%) while median OS (18.8 months) and PFS (10.5 months) distinctly exceeded the results presented here. However, in this study, the median treatment duration was 6 months (TEPIP 1.3 months), and 77% of patients received treatment as first or second line (TEPIP 14%) (39). A recently published prospective Italian trial demonstrated efficacy (ORR 71%) and safety of an all-oral regimen DEVEC resulting in 1-year OS and PFS of 48 and 39%, respectively, despite an old and multiply pretreated population with R/R DLBCL (38). In contrast to the TEPIP trial, the median number of courses administered was higher (median 6 vs. 1 course) and 49% of patients also received rituximab (TEPIP 26%), both factors which have been shown to significantly improve the effect of TEPIP treatment.
While the PEP-C as well as the DEVEC regimen comprise cyclophosphamide as an alkylating agent, the TEPIP schedule uses trofosfamide which might not be available in other countries. Trofosfamide (oral drug) was choosen because it is approved for the use in R/R NHL in Germany. In contrast, the oral form of cyclophosphamide is only approved in breast cancer and auto-immune disease. Since trofosfamide is an oxazaphosphorine that is mainly metabolized to ifosfamide and to a smaller extent to cyclophosphamide, replacing trofosfamide by cyclophosphamide might be possible. Taking the efficacy of PEP-C and DEVEC or of continuous oral cyclophosphamide into account, a replacement strategy seems to be feasible and potentially also effective. However, we do not have any data on the use of cyclophosphamide instead of trofosfamide in the TEPIP regimen.
We acknowledge the limitations of the study presented here. In addition to a partially incomplete data set due to the palliative out-patient setting and the retrospective analysis without a control group, the relatively small number of patients treated and the short median duration of TEPIP administration negatively affect the explanatory power of the results. Additionally, rituximab which has shown to synergistically enhance the effect of all-oral regimens was administered in only a small number of patients. Nevertheless, in elderly patients and patients who received at least two courses and/or a combination with rituximab ORR and survival were remarkable, which underscores the value of TEPIP therapy in the palliative out-patient care of R/R DLBCL patients. Further evaluation in larger cohorts and randomized trials is needed to gain further experience.

DATA AVAILABILITY STATEMENT
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

ETHICS STATEMENT
The studies involving human participants were reviewed and approved by Ethics Committee University of Regensburg (reference number: 20-1901-104). All patients provided their written informed consent to participate in this study.

AUTHOR CONTRIBUTIONS
MAF, SM, WH, MV, AR and DH treated the patients. MAF, MF, MG, MK-S and DH analyzed the data. MAF, AR and DH wrote the manuscript. All authors revised the manuscript critically, approved the final manuscript, and agreed to be accountable for all aspects of the manuscript.

ACKNOWLEDGMENTS
This work is dedicated to Klaus Broß (1941-2020), who as a witty and unconventional forward thinker played a decisive role in the development of the TEPIP regimen and the underlying theory.