Poor outcomes for trial-ineligible patients receiving polatuzumab for relapsed/refractory diffuse large B-cell lymphoma in routine care: An Australian Lymphoma and Related Diseases Registry project

Polatuzumab vedotin (Pola) is an approved therapy in combination with rituximab and bendamustine for relapsed or refractory diffuse large B-cell lymphoma (RR-DLBCL) based on positive results of the landmark phase II randomised G029365 trial. However, trial results for many approved novel therapies in RR-DLBCL have not been replicated in routine care cohorts, as RR-DLBCL patient populations are heterogeneous and trial eligibility is increasingly restrictive. We evaluated outcomes from pola ± bendamustine and rituximab in patients with RR-DLBCL enrolled in a compassionate access program with no alternative treatment options identified via the Australasian Lymphoma and Related Diseases Registry according to their eligibility for the original phase II published study. Of 58 eligible patients, 74% met the criteria deeming them ineligible for the G029365 original study at the time of pola's commencement. Median progression-free survival and overall survival in our cohort were 2.3 and 3.5 months, respectively. In contrast to the landmark trial cohort, more of our patients ceased therapy prior to completion, the majority due to progressive disease and only 8/58 received any subsequent treatment. Dismal outcomes in this Australian real-world population demonstrate trial eligibility is challenging to meet, and newer treatments can be difficult to deliver in routine care. Clinically applicable results from therapeutic studies require trial cohorts to reflect representative clinical populations wherever possible, and more research is required to address the benefit of novel agents in the increasing majority who are ineligible for modern studies.

The influence of immunodeficiency, disease features, and patient characteristics on survival in plasmablastic lymphoma

ABSTRACT

Plasmablastic lymphoma (PBL) is a rare and aggressive non-Hodgkin lymphoma associated with immunodeficiency, characterized by uncertain treatment approaches and an unfavorable prognosis. We conducted a multicenter, international, retrospective cohort study, aiming to characterize the clinical features, risk factors, and outcomes of patients with PBL. Data were collected from 22 institutions across 4 countries regarding patients diagnosed with PBL between 1 January 1999 and 31 December 2020. Survival risk factors were analyzed using both univariate and multivariate regression models. Overall survival (OS) was calculated using Kaplan-Meier statistics. First-line treatment regimens were stratified into standard- and higher-intensity regimens, and based on whether they incorporated a proteasome inhibitor (PI). A total of 281 patients (median age, 55 years) were included. Immunodeficiency of any kind was identified in 144 patients (51%), and 99 patients (35%) had HIV-positive results. The 5-year OS for the entire cohort was 36% (95% confidence interval, 30%-42%). In multivariate analysis, inferior OS was associated with Epstein-Barr virus-negative lymphoma, poor performance status, advanced stage, and bone marrow involvement. In an independent univariate analysis, the international prognostic index was associated with OS outcomes. Neither immunosuppression nor HIV infection, specifically, influenced OS. Among patients treated with curative intent (n = 234), the overall response rate was 72%. Neither the intensity of the treatment regimen nor the inclusion of PIs in first-line therapy was associated with OS. In this large retrospective study of patients with PBL, we identified novel risk factors for survival. PBL remains a challenging disease with poor long-term outcomes.

Immune priming with avelumab and rituximab prior to R-CHOP in diffuse large B-cell lymphoma: the phase II AvR-CHOP study

Immune evasion, due to abnormal expression of programmed-death ligands 1 and 2 (PD-L1/PD-L2), predicts poor outcomes with chemoimmunotherapy in diffuse large B-cell lymphoma (DLBCL). Immune checkpoint inhibition (ICI) has limited efficacy at relapse but may sensitise relapsed lymphoma to subsequent chemotherapy. ICI delivery to immunologically intact patients may thus be the optimal use of this therapy. In the phase II AvR-CHOP study, 28 patients with treatment-naive stage II-IV DLBCL received sequential avelumab and rituximab priming ("AvRp;" avelumab 10 mg/kg and rituximab 375 mg/m2 2-weekly for 2 cycles), R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone for 6 cycles) and avelumab consolidation (10 mg/kg 2-weekly for 6 cycles). Grade 3/4 immune-related adverse events occurred in 11%, meeting the primary endpoint of a grade ≥3 irAE rate of <30%. R-CHOP delivery was not compromised but one patient ceased avelumab. Overall response rates (ORR) after AvRp and R-CHOP were 57% (18% CR) and 89% (all CR). High ORR to AvRp was observed in primary mediastinal B-cell lymphoma (67%; 4/6) and molecularly-defined EBV-positive DLBCL (100%; 3/3). Progression during AvRp was associated with chemorefractory disease. Two-year failure-free and overall survival were 82% and 89%. An immune priming strategy with AvRp, R-CHOP and avelumab consolidation shows acceptable toxicity with encouraging efficacy.

Bendamustine plus rituximab for the treatment of Waldenström Macroglobulinemia: Patient outcomes and impact of bendamustine dosing

Bendamustine and rituximab (BR) therapy is commonly used in the treatment of Waldenström Macroglobulinemia (WM). The impact dose of Bendamustine dose on response and survival outcomes is not well-established, and the impact of its use in different treatment settings is not clear. We aimed to report response rates and survival outcomes following BR, and clarify the impact of depth of response and bendamustine dose on survival. A total of 250 WM patients treated with BR in the frontline or relapsed settings were included in this multicenter, retrospective cohort analysis. Rates of partial response (PR) or better differed significantly between the frontline and relapsed cohorts (91.4% vs 73.9%, respectively; p < 0.001). Depth of response impacted survival outcomes: two-year predicted PFS rates after achieving CR/VGPR vs PR were 96% versus 82%, respectively (p = 0.002). Total bendamustine dose was predictive of PFS: in the frontline setting, PFS was superior in the group receiving ≥1000 mg/m² compared with those receiving 800-999 mg/m² (p = 0.04). In the relapsed cohort, those who received doses of <600 mg/m² had poorer PFS outcomes compared with those who received ≥600 mg/m² (p = 0.02). Attaining CR/VGPR following BR results in superior survival, and total bendamustine dose significantly impacts response and survival outcomes, in both frontline and relapsed settings.

Frontline treatment of follicular lymphoma with atezolizumab and obinutuzumab, with and without radiotherapy (The FLUORO study)

TPS7587

Background: Follicular lymphoma (FL) is the commonest indolent lymphoma, comprising 20% of non-Hodgkin Lymphoma, with approximately 80% of patients (pts) requiring therapy. At present, advanced stage is incurable; most pts require >1 treatment. Overall response rates (ORR) to standard chemoimmunotherapy (bendamustine or CHOP with rituximab or obinutuzumab) approximate 85% with considerable toxicity (grade 3-5 in 69-75%) (Hiddemann 2018). With the FL population predominantly >65 years, 10-year median survival and need for further therapy, efficacious treatments with low toxicity are desirable. PD1/PDL1 axis inhibitors are active in FL. A phase I study of obinutuzumab (O) + atezolizumab (A) induced 57% ORR in pts with rituximab-refractory FL (Palomba 2017). Our phase II ‘1st FLOR’ study, combining nivolumab + rituximab in treatment naïve FL yielded 92% ORR, (54% Complete Response, CR). Toxicity profiles compared favourably with conventional chemotherapy: 41% grade 3-5 events (Hawkes 2021). FL is sensitive to low dose radiotherapy (RT), with abscopal effects reported, and potential to improve treatment efficacy with minimal additional toxicity when combined with PD1/PDL1 inhibitors (Sharabi 2015). This investigator initiated, multicentre single-arm phase II PET-adapted trial aims to assess the response of O + A +/- RT for treatment-naïve FL, reducing treatment-related toxicity using a chemotherapy-free, multi-modality, synergistic regimen. Methods: Eligible pts are >18 years, ECOG 0-2 with untreated, biopsy proven, grade 1-3A stage II-IV FL. Exclusions are significant compressive symptoms, autoimmune disease, pneumonitis and treatment urgency. All pts receive 6 cycles (q21 days) of O 1000mg + A 1200mg (plus O given on days 8 & 15 of cycle 1). Interim PET-CT is performed post cycle 2. Pts with less than CR will undergo RT (4Gy) to residual disease after cycle 3. At end of induction, responding patients will receive maintenance O (up to 12 cycles, 1000mg Q8W). Pts with significant progression will be taken off study. Total follow-up is 2 years post treatment. Primary endpoint is CR rate following 6 x O&A +/- RT. Secondary endpoints include ORR, PFS, OS and adverse events. PET centres are ARTnet accredited with central analysis. An extensive exploratory biomarker substudy is planned. Sample size is 46 according to a Simon’s 2-stage design. If ≥5 positive responses (CR +/- PR) without prohibitive toxicity are seen in the first 15 pts, 31 further pts will be recruited.The trial has currently enrolled 7 pts from 4 Australian sites. Clinical trial information: NCT04962126.

Outcomes of non-myeloablative allogeneic stem cell transplant in older patients with acute myeloid leukaemia in first remission

The benefits of non-myeloablative stem cell transplant in older patients with acute myeloid leukaemia are unclear. We compare the long-term outcomes of this regimen in those aged 55-65 years in first remission with a chemotherapy only cohort that achieved durable morphologic remission. Five-year overall survival was similar (32% vs 33%, P = 0.90), as was relapse-free survival (23% vs 20%, P = 0.37). There was a trend for decreased relapse that was balanced against increased non-relapse mortality with transplantation.

Systemic ALCL Treated in Routine Clinical Practice: Outcomes Following First-Line Chemotherapy from a Multicentre Cohort

INTRODUCTION

Brentuximab vedotin (BV)-CHP is the new standard regimen for first-line treatment of systemic anaplastic large cell lymphoma (sALCL). We undertook a retrospective analysis of consecutive patients diagnosed with sALCL, treated in routine practice, to serve as a benchmark analysis for comparison BV-CHP efficacy in routine practice.

METHODS

Patients aged 16 years or older with sALCL treated in seven UK and Australian centres and from 14 additional centres from the UK Haematological Malignancy Research Network database (n = 214). Treatment allocation was clinician choice and included best supportive care (BSC). Main outcomes were time to treatment failure (TTF) and overall survival (OS). Multivariable analysis for predictors of both TTF and OS was also undertaken.

RESULTS

The median age 52 years (range 16-93), 18% ECOG ≥ 3 and 40% of cases were ALK positive. CHOP (cyclophosphamide, adriamycin, vincristine, prednisolone) was employed in 152 (71%) of patients and CHOEP (CHOP + etoposide) in 4% of patients. For CHOP-treated patients overall response rate (ORR) was 65% and complete response (CR) 47%. Only 9% of patients underwent autologous stem cell transplant (ASCT). With 57 months median follow-up, 4-year TTF and OS were 41.2% (95% CI 33.1-49.1) and 58.9% (95% CI 50.3-66.5) respectively. Multivariable analysis showed ALK+ status was independently associated with superior TTF (HR 0.36, 95% CI 0.21-0.63) but not OS (0.44, 95% CI 0.18-1.07).

DISCUSSION

We present a retrospective analysis with mature follow-up of one of the largest multicentre populations of sALCL available, comparable to similar large retrospective studies. ALK status remains a strong predictor of outcomes.

CONCLUSION

These data serve as a robust benchmark for BV-CHP as the new standard of care for sALCL. Similar real-world evidence with BV-CHP will be desirable to confirm the findings of ECHELON-2.

Abstract CT208: Phase I Dose Escalation Study of Radiotherapy and Durvalumab (MEDI4736) in Relapsed or Refractory Diffuse Large B-cell Lymphoma (DLBCL): The RaDD Study

Background: Most DLBCL & FL responds well to first line treatment, yet relapsed disease outcomes are poor. Immune checkpoint inhibition (ICI) with PD/PD1 inhibitors (PD1i) yield high response rates in some lymphomas; though single agent PD1i yields a disappointing ORR of 10% in heavily pre-treated DLBCL, some responses are durable. RT stimulates anti-tumour immunity through several mechanisms and may enhance response to ICI. Concurrent ICI & RT is synergistic in preclinical studies & solid tumours, improving local & distant (abscopal) response. RT to multiple disease sites may broaden the spectrum of tumour antigen release and overcome clonal variation between disease sites to further augment the immune response. A dose-response relationship between RT and antigen release has yet to be established. This phase I dose escalation study aims to determine the safety profile of RT in combination with durvalumab, an anti-PD-L1 monoclonal antibody, in relapsed/refractory DLBCL and FL.

Study Design and Methods: RaDD (NCT03610061) is a phase I dose escalation study to determine the safety profile of escalating dose and number of sites of RT in combination with durvalumab in relapsed/refractory (RR) DLBCL & FL. Eligible patients (pts) have received ≥ 1 prior line of therapy and are ineligible for or relapsed after autologous stem cell transplant (auto-SCT). Pts with active autoimmune disease, CNS involvement, prior allogeneic-SCT or chronic steroid use are excluded. RT dose and site escalation proceeds according to a 3+3 design with 6 dose levels (cohorts 1-6). Treatment comprises external beam RT to target site(s) daily for 5 days (Cohorts 1-5); Cohort 6 receives a further 5 daily fractions (max 30Gy). Durvalumab 1500mg IV commences day 2 of RT and continues 4-weekly until disease progression. Pts can continue until a second radiological progression if clinical benefit is ongoing. The dose limiting toxicity period is 28 days from start of RT.

The primary endpoint is the toxicity, drug pharmacokinetics, maximum tolerated dose (MTD) and recommended phase two dose (RP2D) of simultaneous RT and durvalumab. Secondary endpoints include response rates, progression-free survival and overall survival.

Correlative studies will examine the tumour-immune system interaction; an exploratory PET substudy with novel tracers for durvalumab (89Zr-Durvalumab) & CD8+ T cells (89Zr -Df-IAB22M2C) will also be performed.

Projected enrolment for determination of the MTD and RP2D is 6-30 pts pending toxicity. Recruitment will continue to 36 pts for secondary endpoint analysis. 22 pts are enrolled to date in the main study, with 2 patients enrolled in the PET-substudy.

Acknowledgements: Victorian Cancer Agency (grant funding - TRP16006), Astra Zeneca (durvalumab and funding), Celgene (funding), Imaginab (89Zr -Df-IAB22M2C).

Citation Format: Kate Manos, Richard Khor, Geoffrey Chong, Jodie Palmer, Michael MacManus, Colm Keane, Andrew M. Scott, Jake Shortt, David Ritchie, Leonid Churilov, Laura Johnston, Tom Witkowski, Allison Barraclough, Sze Ting Lee, Wendi Lin, Rachel Koldej, Eliza Hawkes. Phase I Dose Escalation Study of Radiotherapy and Durvalumab (MEDI4736) in Relapsed or Refractory Diffuse Large B-cell Lymphoma (DLBCL): The RaDD Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT208.

Immune priming with nivolumab followed by nivolumab and rituximab in first-line treatment of follicular lymphoma: The phase 2 1st FLOR study

7560

Background: Standard of care immunochemotherapy in front-line (1L) follicular lymphoma (FL) is highly efficacious but not without significant toxicity. High rates of grade 3-5 adverse events (AEs), primarily infection and bone marrow suppression, are experienced in up to 75% of patients. A more tolerable but equally effective approach is required. PD-1 inhibition, in combination with rituximab (R), increases T cell anti-tumour effect & enhances NK cell antibody dependent cell cytotoxicity, with proven efficacy in relapsed FL. The concept of ‘priming’ the immune system with nivolumab (N) prior to tumour-directed therapy has rationale and evidence, but the safety of this approach in 1L FL is not described. Methods: ‘1st FLOR’ (NCT03245021) is an open-label, multi-centre, phase 2, Simon’s 2-stage study of N + R (N = 39). Key eligibility were stage III-IV grade 1-3A FL requiring 1L systemic therapy; ECOG ≤2; adequate organ function. All patients (pts) receive induction N 240mg IV 2-weekly for 4 cycles. Pts with complete response (CR) receive 4 further cycles of 240mg IV N monotherapy then 12 cycles of maintenance N 480mg IV 4-weekly. Pts with < CR had 240mg N plus 375mg/m2 IV R 2-weekly for 4 cycles followed by maintenance N+R (N 480mg 4 weekly for 12 cycles; R 12 weekly for 8 cycles). Primary endpoint (EP) was ≥ G3 toxicity rate during induction. Secondary EPs; response rate by Lugano response criteria, overall toxicity, PFS, OS. Results: Between September 2017 to March 2020, 39 pts were enrolled. Baseline characteristics included median age of 54 (range: 28-79). stage IV disease in 67%, B Symptoms & bulk (≥7cm) in 23% each, intermediate-high risk FLIPI in 74%. The primary EP was met, with only 16 pts (41%) having ≥G3 toxicity at end of induction. Non-immune AEs were predominantly G1-2; most commonly infection (67%) & fatigue (64%). G3-4 Immune-related AEs were infrequent and included pancreatitis plus hepatitis (N = 1), pancreatitis alone (N = 1), rash (N = 1), transaminitis (N = 2), hypocortisolism (N = 1), hyperglycaemia (N = 3) and asymptomatic lipase/amylase increase (N = 3). Median follow-up was 17.5 months (range: 7-39). Overall response rate was 92% (36/39) with CR in 54% (21/39). Median time to CR was 5 months (m) (range: 2-25). Nine pts (23%) discontinued treatment; 7 due to progressive disease (1 pt died of transformed FL), 2 developed constitutional symptoms (1 stable disease, 1 partial response). In 25 evaluable pts, 12m PFS & OS is 72% (CI 51-88) & 96% (CI 80-100). Biomarker analysis is in progress. Conclusions: Immune-priming with single-agent N, then combination N+R in 1L FL is associated with favourable toxicity and high ORR & CR rates potentially providing an alternative to chemotherapy. Acknowledgements: Bristol-myers Squibb provided funding and nivolumab for this study. Clinical trial information: NCT03245021.

Evolution of eligibility criteria for diffuse large B-cell lymphoma randomised controlled trials over 30 years

Eligibility criteria for randomised control trials (RCT) in diffuse large B-cell lymphoma (DLBCL) may be becoming increasingly strict. In this analysis, 42 first-line phase III RCTs enrolling DLBCL patients since 1990 were identified from PubMed and clinicaltrials.gov. Changes in 31 individual eligibility criteria were assessed using three pre-defined eras [(1) 1993-2005; (2) 2006-2013; and (3) 2014-2020]. The presence of 15/31 criteria increased significantly over time, and the total number of criteria per study also increased over time [median Era 1: 14·5, interquartile range (IQR) 12·6-16·4; Era 2: 21, 18·8-23·3; Era 3: 23, 21-25; P < 0·001]. When each trial's eligibility criteria were applied to 215 consecutive patients from an institutional database treated between 2010 and 2020, a median of 57% (IQR 47-70) of patients were hypothetically eligible for trial enrolment. The median percentage of patients eligible was 68% (56-91), 54% (37-81) and 47% (38-82) for Era 1, 2 and 3 respectively (P = 0·004). Phase III front-line DLBCL trial criteria have become increasingly restrictive over the last three decades, resulting in a diminishing proportion of trial-eligible patients, with less than 50% of our patients eligible for modern-era studies. This potentially impacts generalisability of recent trial results and will likely limit recruitment to ongoing studies.

Myeloid somatic mutation panel testing in myeloproliferative neoplasms

Myeloproliferative neoplasms are characterised by somatic mutations in pathways that regulate cell proliferation, epigenetic modifications, RNA splicing or DNA repair. Assessment of the mutational profile assists diagnosis and classification, but also aids assessment of prognosis, and may guide the use of emerging targeted therapies. The most practical way to provide information on numerous genetic variants is by using massively parallel sequencing, commonly in the form of disease specific next generation sequencing (NGS) panels. This review summarises the diagnostic and prognostic value of somatic mutation testing in Philadelphia-negative myeloproliferative neoplasms: polycythaemia vera, essential thrombocythaemia, primary myelofibrosis, chronic neutrophilic leukaemia, systemic mastocytosis, and chronic eosinophilic leukaemia. NGS panel testing is increasing in routine practice and promises to improve the accuracy and efficiency of pathological diagnosis and prognosis.

Ibrutinib for central nervous system lymphoma: the Australasian Lymphoma Alliance/MD Anderson Cancer Center experience

Primary and secondary central nervous system lymphomas (PCNSL/SCNSL) are aggressive rare malignancies with dismal outcomes. Encouraging data have emerged from Phase I/II clinical trials treating relapsed/refractory PCNSL/SCNSL with ibrutinib. We analysed 33 patients who received ibrutinib, alone or with other therapies, for PCNSL (n = 9) or SCNSL (n = 24). The objective response rate was 58% (complete response 55%). The median progression-free survival and overall survival for patients with PCNSL were both 3·1 months; for SCNSL, 10·2 and 11·5 months respectively. Only one invasive fungal infection was observed, despite concurrent or recent use of dexamethasone 8-16 mg daily in 14 patients (42%). Ibrutinib has encouraging activity in these aggressive malignancies.

Phase I study of radiotherapy (RT) & durvalumab in relapsed/refractory diffuse large B-cell lymphoma (DLBCL) & follicular lymphoma (FL): The RADD study

TPS8075

Background: Most DLBCL & FL responds well to first line treatment, yet relapsed disease outcomes are poor. PD1/PDL1 inhibitors yield high response rates in some lymphomas, but single agent therapy in heavily pre-treated pts are disappointing. RT stimulates anti-tumor immunity through several mechanisms and may enhance response to immune checkpoint inhibition (ICI). Concurrent ICI & RT is synergistic in preclinical studies & solid tumors, improving local & distant (abscopal) response. RT to multiple disease sites may broaden the spectrum of tumor antigen release and overcome clonal variation between disease sites to further augment the immune response. Methods: RaDD (NCT03610061) is a phase I, 3+3 dose escalation study to determine the safety profile of escalating dose & number of sites of RT in combination with Durvalumab (anti-PD-L1 antibody) in RR DLBCL & FL. Eligible pts (i.e. ≥1 prior therapy, ineligible for auto-SCT, no contraindication to PDL1i) receive 5 fractions of external beam RT to target site(s). 5 RT dose & site levels are included (dose range 2.5Gy-20Gy to 1-3 sites). Durvalumab 1500mg IV commences day 2 of RT and continues 4-weekly until confirmed disease progression. The DLT period is 28 days from start of RT. Primary endpoint is the recommended phase two dose (RP2D) of RT in combination with durvalumab. Secondary endpoints include response rates, PFS & OS. Correlative studies will examine the tumour-immune system interaction; an exploratory PET substudy with novel tracers for durvalumab (89Zr-Durvalumab) & CD8+ T cells (89Zr -Df-IAB22M2C) will also be performed. Projected enrollment for determination of maximum tolerated dose (MTD) & RP2D is 6-30 pts pending toxicity. Recruitment will continue to 36 pts for secondary endpoint analysis. 9 pts are enrolled across cohorts 1-3 to date. Clinical trial information: NCT03610061 .

A multicenter retrospective comparison of induction chemoimmunotherapy regimens on outcomes in transplant-eligible patients with previously untreated mantle cell lymphoma

Mantle cell lymphoma (MCL) is an uncommon and typically aggressive form of lymphoma. Although often initially chemosensitive, relapse is common. Several induction and conditioning regimens are used in transplant-eligible patients, and the optimal approach remains unknown. We performed an international, retrospective study of transplant-eligible patients to assess impact of induction chemoimmunotherapy and conditioning regimens on clinical outcomes. We identified 228 patients meeting inclusion criteria. Baseline characteristics were similar among the induction groups except for some variation in age. The type of induction chemoimmunotherapy received did not influence overall response rates (ORRs) (0.43), progression-free survival (PFS) (P > .67), or overall survival (OS) (P > .35) on multivariate analysis (PFS and OS). Delivery of autologous stem cell transplant (ASCT) was associated with favorable PFS and OS (0.01) on univariate analysis only; this benefit was not seen on multivariate analysis-PFS (0.36) and OS (0.21). Compared with busulfan and melphalan (BuMel), the use of the carmustine, etoposide, cytarabine, melphalan (BEAM)-conditioning regimen was associated with inferior PFS (HR = 2.0 [95% CI 1.1-3.6], 0.02) but not OS (HR = 1.1 [95% CI 0.5-2.3], 0.81) on univariate analysis only. Within the limits of a retrospective study and modest power for some comparisons, type of induction therapy did not influence ORR, PFS, or OS for transplant-eligible patients with MCL. International efforts are required to perform randomized clinical trials evaluating chemoimmunotherapy induction regimens.

Effect of early postoperative enteral feeding on the healing of colonic anastomoses in rats. Comparison of three different enteral diets

This experimental study compares the effects of early postoperative administration of three enteral diets of different compositions on the healing of colonic anastomoses. Sixty Wistar rats were subjected to colonic anastomoses. Following surgery, the rats were randomly allocated to four groups of 15 each. The rats in control group A received an electrolyte and glucose solution, the rats in group B received a complete balanced nutrition, in group C a complete balanced nutrition supplemented with fiber and in group D an isocaloric specialized elemental nutrition enriched with glutamine. The rats were sacrificed on day 7 following operation. Rupture of the anastomosis was higher in rats of the control group compared to the other three groups. Adhesion formation was more extensive in group A in comparison to the other three groups. The anastomotic bursting pressures were statistically significantly higher in groups C and D compared to the other two groups (p < 0.05). There was no statistically significant difference between group C and D (p > 0.05) while a statistically significant difference was noted between group B and group A (p < 0.05). Histological examination showed more profound inflammatory reaction in group A compared to the other three groups. There was also a statistically significant difference between group B and groups C and D while inflammatory reaction was of no statistically significant difference between group C and group D. Healing of the anastomoses was statistically significantly impaired in group A compared to the other three groups. There was no statistically significant difference between group C and group D while a statistically significant difference was found between group B and groups C and D. In conclusion, early postoperative enteral feeding improves healing of experimental colonic anastomoses in rats. This effect was more evident when fiber-supplemented diets or diets enriched with glutamine were administered.