Retrospective analysis of doxorubicin and prednisone as first-line therapy for canine B-cell lymphoma

Comparing continuous micromixing and extrusion downsizing for PEGylated nanoliposomes remotely loaded with doxorubicin or the steroid pro-drug methylprednisolone hemisuccinate

Since the FDA approval of the first nanodrug Doxil® in 1995, twenty subsequent liposome and lipid nanoparticle (LNP) based drugs (of which 10 are nanodrugs), were approved by the FDA. The application of such drug-products was considerably boosted by the mRNA-LNP based vaccines used to stop the COVID-19 pandemic. Research on lipid-based vesicles and nanoparticles for drug delivery dates to the 1970s and has culminated in both continuous flow and extrusion-based fabrication processes for current state-of-the-art GMP industrial production of nanoliposomes and lipid nanoparticles. In this study, we compare these two approaches for the preparation of two PEGylated nanoliposome-based drug-products, keeping all other production steps leading to the final drug-product identical. One of these products, generic Doxil®, is remotely and actively loaded with the anthracycline doxorubicin (an amphipathic weak base) driven by a transmembrane ammonium gradient, while the other is methylprednisolone hemisuccinate (an amphipathic weak acid) remotely and actively loaded via a transmembrane acetate gradient. We demonstrate that a microfluidics-based micromixer approach yields equivalent or even better drug-products, especially since the downsizing by microfluidics is not performed above the temperature range of lipid phase transition. The main difference in the physico-chemical features is that size distribution of the microfluidics prepared PEGylated nano liposomes was significantly narrower and morphological analysis by cryo-TEM confirmed higher homogeneity. An additional advantage of the microfluidic approach is that it is a continuous production. Therefore, it enables the direct production of large volumes of high-quality nano-liposomal based drug-products.

Alternating rabacfosadine and doxorubicin for treatment of naïve canine lymphoma

The current standard of care treatment for canine lymphoma is a multi-agent, CHOP-based chemotherapy protocol. Single agent doxorubicin (DOX) is less burdensome; however, multi-agent chemotherapy protocols are often superior. The recently approved drug rabacfosadine (RAB, Tanovea) provides an attractive option for combination therapy with DOX, as both drugs demonstrate efficacy against lymphoma and possess different mechanisms of action. A previous study evaluating alternating RAB/DOX reported an overall response rate (ORR) of 84%, with a median progression-free survival time (PFS) of 194 days. The aim of this prospective trial was to evaluate the same protocol in an additional population of dogs. Fifty-nine dogs with treatment naïve lymphoma were enrolled. RAB (1.0 mg/kg IV) was alternated with DOX (30 mg/m2 IV) every 21 days for up to six total treatments (3 cycles). Response assessment and adverse event (AE) evaluation were performed every 21 days using VCOG criteria. The ORR was 93% (79% CR, 14% PR). The median time to maximal response was 21.5 days; median PFS was 199 days. T cell immunophenotype and lack of treatment response were predictive of inferior outcomes. AEs were mostly gastrointestinal. Six dogs developed presumed or confirmed pulmonary fibrosis; four were grade 5. One dog experienced grade 3 extravasation injury with RAB that resolved with supportive treatment. These data mirror those of the previously reported RAB/DOX study, and support the finding that alternating RAB/DOX is a reasonable treatment option for canine lymphoma.

Review of Canine Lymphoma Treated with Chemotherapy-Outcomes and Prognostic Factors

While canine lymphoma is a relatively common and important disease seen by veterinarians, there are limited comprehensive reviews of the literature regarding the remission and survival times following chemotherapy, and the associated prognostic factors. This comprehensive thematic review covers the available veterinary literature covering treatment outcomes and identified prognostic factors. A lack of standardised approaches to evaluate and report the outcomes was identified, including factors that would alter the duration of responses by weeks, or occasionally months. After publication of the suggested reporting criteria, this has improved but is still not uniformly applied. The prognostic factors included for evaluation varied from as few as three to seventeen, with over 50 studies using only univariate analysis. Individual papers reported much longer outcomes than others, but assessing the outcomes overall, there has been minimal change over the last 40 years. This supports the belief that novel approaches for lymphoma therapy will be required to substantively improve outcomes.

Procarbazine, prednisolone and cyclophosphamide (PPC) oral combination chemotherapy protocol for canine lymphoma

Orally administered daily chemotherapy offers a novel treatment approach for canine lymphoma in a population of dogs that have failed or not tolerated maximum tolerable dose chemotherapy. A multidrug oral chemotherapy protocol was designed and implemented for the treatment of fifty dogs with multicentric lymphoma with minimal side effects. The protocol consisted of oral procarbazine, prednisolone and cyclophosphamide (PPC) administered daily. Efficacy and toxicity were evaluated by clinical and laboratory evaluation. An overall response rate of 70% was achieved, with 24% and 46% of dogs having a partial and complete response, respectively, to treatment with the PPC protocol. Response to the PPC protocol (complete or partial) and age were the only factors identified as prognostic for time from initiation of the PPC chemotherapy until death. Overall, the protocol was very well tolerated with only one dog requiring protocol discontinuation due to grade 4 thrombocytopenia. Eight dogs recorded gastrointestinal toxicities, seven grade I and one grade II toxicity. These findings demonstrate that the administration of a continuous oral combination chemotherapy can provide comparable survival times in the rescue setting in dogs with multicentric lymphoma with minimal side effects.

Multicenter, randomized, double‐blinded, placebo‐controlled study of rabacfosadine in dogs with lymphoma

Background

Rabacfosadine (RAB, Tanovea‐CA1) is a novel chemotherapy agent conditionally approved for the treatment of lymphoma in dogs.

Hypothesis/Objectives

To determine the efficacy and safety of RAB in dogs with lymphoma.

Animals

One hundred and fifty‐eight client‐owned dogs with naïve or relapsed multicentric lymphoma were prospectively enrolled from January to October 2019.

Methods

Dogs were randomized to receive RAB or placebo at a 3 : 1 ratio. Treatment was given every 21 days for up to 5 treatments. Study endpoints included progression‐free survival (PFS), overall response rate (ORR) at a given visit, best overall response rate (BORR), and percent progression free 1 month after treatment completion. Safety data were also collected.

Results

The median PFS was significantly longer in the RAB group compared to placebo (82 vs 21 days; P < .0001, HR 6.265 [95% CI 3.947‐9.945]). The BORR for RAB‐treated dogs was 73.2% (50.9% complete response [CR], 22.3% partial response [PR]) and 5.6% (0% CR, 5.6% PR) for placebo‐treated dogs (P < .0001). One month after the last treatment, 37 RAB‐treated dogs (33%) were progression free compared with no placebo‐treated dogs (P < .0001). The most common adverse events observed in the RAB group were diarrhea (87.5%), decreased appetite (68.3%), and vomiting (68.3%) and were generally low grade and reversible. Serious adverse events were reported in 24 RAB‐treated (20%) and 5 placebo‐treated dogs (13%).

Conclusions and Clinical Importance

Rabacfosadine demonstrated statistically significant antitumor efficacy in dogs with lymphoma when administered every 21 days for up to 5 treatments as compared to placebo.

Toxicity, outcome, and management of anthracycline overdoses in 16 dogs

Background

Despite multiple reports of chemotherapy overdoses (ODs) in human and veterinary medicine, anthracycline ODs have been described infrequently.

Hypothesis/Objectives

Describe toxicities, treatments, and overall outcome after anthracycline OD in dogs.

Animals

Twelve mitoxantrone (MTX) and 4 doxorubicin (DOX) ODs were evaluated.

Methods

Multicenter retrospective analysis. The American College of Veterinary Internal Medicine oncology and internal medicine listservs were solicited for cases in which a chemotherapy OD occurred.

Results

Sixteen anthracycline cases were collected. Anthracycline ODs occurred because of an error in chemotherapy preparation (n = 9), or dose miscalculation (n = 7). The overall median OD was 1.9× (range, 1.4‐10×) the prescribed amount. Most ODs were identified immediately after drug administration (n = 11), and the majority of patients were hospitalized on supportive care (n = 11) for an average of 8 days (range, 3‐34 days). Adverse events after the OD included neutropenia (94%), thrombocytopenia (88%), anemia (63%), diarrhea (63%), anorexia (56%), vomiting (38%), lethargy (31%), and nausea (25%). Two patients did not survive the OD. High grade neutropenia was common and did not appear to be mitigated by the administration of filgrastim.

Conclusions and Clinical Importance

All patients received supportive care after identifying the OD and death was uncommon. Further evaluation is needed to determine ideal therapeutic guidelines anthracycline OD.

Serum IL-6 and MCP-1 concentrations in dogs with lymphoma before and after doxorubicin treatment as a potential marker of cellular senescence

BACKGROUND

Chemotherapy can induce cellular senescence and a secretory phenotype characterized by an increased expression of inflammatory cytokines, such as IL-6 and MCP-1. Increased IL-6 and MCP-1 serum concentrations have been documented in dogs with lymphoma, but no studies have evaluated the effects of chemotherapy on cytokine concentrations.

OBJECTIVES

To measure IL-6 and MCP-1 in 16 client-owned dogs with lymphoma, at baseline and before and after doxorubicin, as a potential marker for senescence and correlate cytokine concentrations with treatment response and toxicities.

METHODS

Serum IL-6 and MCP-1 concentrations at baseline, 0-h, 3-h, 6-h, 24-h and 1 week post doxorubicin were measured using a canine ELISA. We hypothesized that IL-6 and MCP-1 concentrations would increase following doxorubicin as a result of induction of cellular senescence.

RESULTS

IL-6 concentrations were unchanged from baseline to 0-h but significantly decreased 1 week post doxorubicin (p = 0.001) compared to 0-6 h (p = 0.045) and 24-h (p = 0.001) time points. MCP-1 concentrations significantly decreased from baseline to 0-h (p = 0.003). Compared to 0-6 h, MCP-1 concentrations transiently increased at 24-h (p = 0.001) and decreased at 1 week (p = 0.014) post doxorubicin. Changes in IL-6 and MCP-1 concentrations did not correlate with leukocyte count, response to treatment or chemotherapy toxicities.

CONCLUSIONS

Changes in IL-6 and MCP-1 concentrations did not support doxorubicin-induced cellular senescence or correlate with leukocyte count, response to treatment or chemotherapy toxicity. However, our results suggest that remission status and doxorubicin treatment may influence cytokine concentrations and future studies are warranted to investigate the role of these cytokines as biomarkers.

Cyclophosphamide and prednisolone for chemotherapy naïve B cell multicentric lymphoma in dogs: 32 cases (2017-2021)

OBJECTIVES

The aim of this study was to characterise the response rate and toxicity profile of cyclophosphamide and prednisolone given to dogs with newly diagnosed, chemotherapy naïve, B cell multicentric lymphoma.

MATERIALS AND METHODS

Dogs with diagnosed with B cell lymphoma naïve to chemotherapy treatment were prospectively identified at the author's institution (2017 to 2021) and given cyclophosphamide as their initial chemotherapeutic agent in combination with prednisolone with owner's consent. Signalment, laboratory findings, stage, treatment response and toxicity were recorded.

RESULTS

Thirty-two dogs were included in the study. The overall response rate in this population of dogs was 84%. Twenty dogs (62%) had a partial response, three dogs (9%) had a complete response, four dogs (12%) had stable disease and five dogs (15%) had progressive disease. Side effects were noted in 47% of patients, with neutropaenia being the most commonly reported.

CLINICAL SIGNIFICANCE

Cyclophosphamide and prednisolone were well-tolerated with limited side effects. The response rate observed in this cohort of dogs with chemotherapy-naïve B cell multicentric lymphoma is promising. Further comparative studies are required to confirm the safety and effectiveness of this intervention.

Evaluation of the Proliferative Activity of Diffuse Large B-Cell Lymphoma (DLBCL) in Dogs with Respect to Patient Eligibility for Anthracycline-Based Chemotherapy

Simple Summary

Canine lymphomas usually have aggressive behavior, but respond well to chemotherapy. Despite proper diagnosis and numerous available therapeutic regimens, it is difficult to determine the prognosis and choose the optimal method of treatment in each individual patient. Diffuse large B-cell lymphoma is the most commonly diagnosed histological subtype of canine lymphoma and is treated with anthracyclines alone or in combination with other chemotherapeutics. A new diagnostic marker of prognostic and predictive value is topoisomerase IIα, which also constitutes a molecular target for anti-cancer drugs belonging to the group of topoisomerase IIα inhibitors including anthracyclines. Proliferative activity was estimated in samples of enlarged lymph nodes in dogs with diffuse large B-cell lymphoma based on mitotic count and immunohistochemical evaluation of topoisomerase IIα and Ki67 antigen expression with a view to qualifying patients for anthracycline-base chemotherapy. It has been shown that higher levels of topoisomerase IIα expression corresponded to a higher mitotic count but not to Ki67 index. These results indicate that an immunohistochemical evaluation of topoisomerase IIα expression can be used to develop a diagnostic-clinical protocol for the treatment of dogs with diffuse large B-cell lymphoma using anthracycline-based chemotherapy.

Abstract

Different types of canine lymphoma respond differently to chemotherapy and have different prognoses. Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma in dogs. Topoisomerase II alpha (TOPIIα) protein has been shown to be a proliferation marker associated with prognostic significance. The aim of the study was to determine the relationship between TOPIIα expression, mitotic count (MC), and Ki67 antigen index in DLBCL in dogs, taking into account the applicability of these parameters to select the chemotherapy protocol with emphasis on the use of anthracycline drugs. Samples of formalin-fixed paraffin-embedded lymph nodes from 34 dogs with DLBCL were immunohistochemically labelled with anti-TOPIIα and Ki67. The number of positive cells and the intensity of the reaction were taken into account in order to assess TOPIIα expression. MC was estimated in the hematoxylin and eosin-stained slides in the area of 2.37 mm². Positive association between TOPIIα and MC, but no association between TOPIIα and Ki67 was found. It can be concluded that the immunohistochemical determination of TOPIIα as a molecular target for drugs from the anthracycline group may be used in association with MC to establish a diagnostic-clinical protocol for selecting dogs with DLBCL for treatment with anthracycline drugs.

Response-based modification of CHOP chemotherapy for canine B-cell lymphoma

Despite high initial response rates, a subset of dogs with B-cell lymphoma responds less robustly to CHOP-based chemotherapy and experiences shorter survival. One hundred and four dogs with nodal B-cell lymphoma were treated with a response-based CHOP (RBCHOP) protocol modified based on response to individual drugs during the first chemotherapy cycle. Dogs achieving complete (CR) or partial response (PR) at week 3, following treatment with vincristine and cyclophosphamide, received RBCHOP 1 (n = 72), a protocol sequentially rotating vincristine, cyclophosphamide, and doxorubicin. Dogs without a detectable response at week 3 that subsequently achieved CR or PR following treatment with doxorubicin received RBCHOP 2 (n = 14), in which four doses of doxorubicin were given consecutively followed by vincristine and cyclophosphamide. Dogs that failed to respond at week 3 and then to doxorubicin at week 5 assessment were offered rescue chemotherapy (RBCHOP 3, n = 18). Median progression free survival (PFS) and overall survival time (OST) were similar between RBCHOP 1 (PFS 210 days, OST 354 days) and RBCHOP 2 (PFS 220 days, OST 456 days), but significantly shorter for RBCHOP 3 (PFS 34 days, OST 80.5 days, P < 0.001). No presenting signalment nor hematologic variable differentiated patient cohort, however, dogs in RBCHOP 2 and RBCHOP 3 were more likely to have a lymphocytosis at diagnosis (P = 0.02 and 0.04, respectively). Protocol modification based on response during the first cycle resulted in similar toxicity profiles and outcomes to previously published variants of CHOP, and prognosis remained poor for dogs failing to respond during the first treatment cycle.

Rabacfosadine for naïve canine intermediate to large cell lymphoma: Efficacy and adverse event profile across three prospective clinical trials

While current lymphoma therapies induce remission in most dogs, drug‐resistant relapse is common, creating a need for novel agents. Rabacfosadine (RAB), a double prodrug of the acyclic nucleotide phosphonate 9‐(2‐phosphonylmethoxyethel) guanine (PMEG), preferentially targets lymphoma cells with reduced systemic toxicity compared with PMEG. Previous studies evaluating RAB administered every 21 days have suggested efficacy in both naïve and relapsed subjects; however, no large studies of RAB as a single agent have been reported in previously untreated dogs with intermediate to large cell lymphoma. The purpose of this study was to evaluate the safety and efficacy of RAB in dogs with previously untreated (excluding corticosteroids) lymphoma. Sixty‐three dogs received up to five RAB treatments every 21 days (16 at 0.82 mg/kg and 47 at 1.0 mg/kg) as a 30 minutes intravenous infusion, with (n = 23) or without (n = 40) concurrent corticosteroids. Response assessment and adverse event (Ae) evaluation were performed every 21 days via Veterinary Cooperative Oncology Group (VCOG) criteria. The overall response rate was 87% (52% CR, 35% PR). The overall median progression free interval was 122 days (199 for CR, 89 for PR and 153 days for all responders). T‐cell immunophenotype and corticosteroid pre‐treatment were predictive of inferior outcomes on multivariate analysis. AEs were most commonly of gastrointestinal origin (hyporexia/diarrhoea) and generally resolved with supportive treatment and/or dosage adjustment. Three dogs experienced VCOG‐CTCAE grade 5 delayed pulmonary fibrosis. In conclusion, RAB administered every 3 weeks is generally well tolerated and demonstrates substantial antitumour activity in dogs with previously untreated intermediate to large cell lymphoma.

Randomized, double-blind trial of F14512, a polyamine-vectorized anticancer drug, compared with etoposide phosphate, in dogs with naturally occurring lymphoma

Purpose: F14512 is an epipodophyllotoxin derivative from etoposide, combined with a spermine moiety introduced as a cell delivery vector. The objective of this study was to compare the safety and antitumor activity of F14512 and etoposide phosphate in dogs with spontaneous non-Hodgkin lymphoma (NHL) and to investigate the potential benefit of F14512 in P-glycoprotein (Pgp) overexpressing lymphomas.

Experimental Design: Forty-eight client-owned dogs with intermediate to high-grade NHL were enrolled into a randomized, double-blind trial of F14512 versus etoposide phosphate. Endpoints included safety and therapeutic efficacy.

Results: Twenty-five dogs were randomized to receive F14512 and 23 dogs to receive etoposide phosphate. All adverse events (AEs) were reversible, and no treatment-related death was reported. Hematologic AEs were more severe with F14512 and gastrointestinal AEs were more frequent with etoposide phosphate. F14512 exhibited similar response rate and progression-free survival (PFS) as etoposide phosphate in the global treated population. Subgroup analysis of dogs with Pgp-overexpressing NHL showed a significant improvement in PFS in dogs treated with F14512 compared with etoposide phosphate.

Conclusion: F14512 showed strong therapeutic efficacy against spontaneous NHL and exhibited a clinical benefice in Pgp-overexpressing lymphoma superior to etoposide phosphate. The results clearly justify the evaluation of F14512 in human clinical trials.

Aldoxorubicin-loaded nanofibers are cytotoxic for canine mammary carcinoma and osteosarcoma cell lines in vitro: A short communication

Chemotherapeutic drugs are given parenterally to treat various canine tumors. A limitation of parenteral administration is low drug penetration into the tumor, which reduces tumoricidal activity. Various drug carriers have been used to enhance tumor delivery, including albumin, liposomes and nanoparticles. A novel peptide-based nanofiber precursor (NFP) has been developed that is designed to take advantage of the leaky tumor neovasculature to promote drug delivery after parenteral administration. In this study, we loaded aldoxorubicin, an albumin-bound prodrug version of doxorubicin, onto NFP and tested the in vitro cytotoxicity in canine mammary carcinoma (CMT12, CMT25) and osteosarcoma (HMPOS, D-17, Abrams) cell lines. The half maximal inhibitory concentration (IC50) was determined with a luminescence-based cell viability assay. The IC50 for aldoxorubicin-loaded NFP was lower than free aldoxorubicin or doxorubicin in all cell lines, whereas non-drug loaded NFP had no cytotoxic effects. There were differences in IC50 between the osteosarcoma lines, with lower and higher IC50 for HMPOS and D-17 cells, respectively, with all drugs (aldoxorubicin-loaded NFP, free aldoxorubicin or free doxorubicin). Our results indicate that drug-loaded NFPs are cytotoxic for various canine mammary carcinoma and osteosarcoma cell lines in vitro and hold promise as a mechanism for enhancing delivery of chemotherapeutic agents to canine tumors.