APAVAC® autologous therapeutic vaccine and TP53 gene
|
|
Principle of targeted therapy
For several years, cancer immunotherapy has been moving towards personalised treatment. Targeted therapy now takes into account inter- and intra-individual variability in cancer type, genetics, epigenetics, microenvironment, diet, etc. In this context of personalised medicine, APAVAC® treatment is similar to an autologous practice exploiting the over-expressed intrinsic antigenicity of the treated patient's tumour. The role of this active immunotherapy has been explored in veterinary medicine in canine lymphoma.
An increased proportion of non-neoplastic T cells has been shown to correlate with significantly longer time to lymphoma progression (TTP) (1), as well as improved side-effect free survival (2,3). But this personalisation can be made even more precise, so that treatment is truly tailored to the mutations of the patient's own tumour. One of the goals is to predict, on the basis of genomic alterations in the tumour, whether the patient will have a good or poor response to treatment in terms of overall survival and tumour-free interval.
|
|
|
|
Understanding the TP53 gene ?
There is a P53 gene known as the ‘tumour suppressor’ or TP53 for ‘Tumour Protein 53’, sometimes nicknamed the ‘guardian of the genome’, which is a small protein (53,000 dalton) transcription factor. This function enables it to regulate or induce the transcription of various genes that have a particular influence on the unfolding of the cell multiplication cycle, DNA repair and the triggering of cell death (or apoptosis) (4).
The P53 gene plays an initiating role by sending signals to other genes essential for repairing damaged DNA chains. If the DNA cannot be repaired, it prevents the cell from dividing (blocking the cell cycle in the G1 phase) and instructs it to die instead of multiplying.
On the other hand, when this gene is mutated, it can no longer play this role and cells with damaged DNA (cancer cells) continue to divide in an anarchic and disorderly fashion.
Globally and in human health, depending on the authors and also on ethnic origin, cancer cells can be considered to have at least one mutated allele of the P53 gene in 35 (5) to 50 (6) % of tumours.
In veterinary medicine, this type of data, which is more difficult to access, is sometimes obtained by high throughput sequencing of cohort samples such as 65% TP53 missense mutation for canine osteosarcoma (7) or 66% for canine haemangiosarcoma (8).
|
|
|
|
Understanding WES ?
Whole Exome Sequencing (WES) (or high-performance whole genome sequencing) enables all the coding regions of the human or animal genome to be deciphered in a single step. By comparing the genomes of healthy tissues and tumours, it is possible to differentiate between constitutional mutations and somatic mutations corresponding to the specific genotype of cancer cells.
By applying this technique to a population of 77 dogs of breeds predisposed to Diffuse Large Cell B Lymphoma (DLBCL), treated either with chemotherapy alone or with a combination of chemotherapy and APAVAC®, the University of Turin team (9,10) aimed to clarify the genetic changes likely to occur in this type of tumour. The principle was to identify the main genes whose somatic mutations (comparison between healthy skin cells and the tumour) were frequently found, and then to search for a possible correlation between the most frequently mutated genes and the clinico-pathological characteristics of the animals treated (11).
source Illustration: "Le séquençage des génomes - G. Furelaud, Y. Esnault - Planet-vie.ens.fr"
|
|
|
|
Influence of TP 53 mutation
Overall, for all 77 dogs included in the study, treatment had a significant impact on time to progression or lymphoma-specific survival (11). Indeed, dogs treated with chemo-immunotherapy (n=45; 58.4%) had a better outcome than dogs receiving chemotherapy alone (n=32; 41.6%). However, faced with the disparity in responses, the authors then sought to assess the genomic landscape of diffuse large B-cell lymphoma from this population in order to identify distinct subtypes with potential clinical and therapeutic implications. Conducted for the first time on such a large population of dogs treated for LBDGC, whole genome sequencing made it possible to identify the types of recurrent genetic alterations and their functional impact on the ‘good or poor responder’ nature of APAVAC® treatment and, in the medium term, to suggest new opportunities for immunotherapy.
In this series (11), TP53 mutations were frequently found by WES: 24 mutations detected in 19 dogs (24.7%), 19 of which were missense mutations (79.2%). These results were validated in a second group of dogs, maintaining a similar frequency and prognostic significance. Mutation of TP53 leads to disruption of checkpoint responses to DNA damage and contributes to genomic and chromosomal instability. It should also be noted that most of the mutations affected the DNA-binding domain of P53, which enabled the authors to put forward the hypothesis of an inactivating effect of this mutation (11).
|
|
|
|
Please note There is no single diffuse large B-cell lymphoma but rather a number of diffuse large B-cell lymphomas that are highly heterogenous in clinical, histological and molecular terms.
Transcriptional signatures and mutational profiles will be added to morphological and phenotypic data, which already exist, to provide a better understanding of this heterogeneity and potentially enable innovative targeted therapies to be proposed.
|
|
A prognostic algorithm to identify the best therapy
For example, the TP53 gene, which is also involved in the regulation of apoptosis and the cell cycle in dogs, when mutated in the tumour, has very often been identified as a so-called missense mutation (change of a nucleotide in a codon) and, in terms of survival, results in a poor prognosis following treatment. On the other hand, the absence of a mutation in this gene (known as a wild-type gene) guarantees the efficacy of APAVAC® immunotherapy, which can lead to a threefold increase in lymphoma-specific survival (LSS) compared with the group of animals treated with chemotherapy alone.
Furthermore, TP53 mutations were associated with age and significantly enriched in dogs diagnosed at stage IV of the disease (P=0.001).The prognostic relevance of TP53 mutations has been explored and measured by the authors (12). Indeed, mutated dogs (TP53mut) had a significantly shorter TTP and LSS than non-mutated dogs (TP53wt).
A prognostic chart ( https://compbiomed.hpc4ai.unito.it/canine-dlbcl/ ) including the parameters of :
- the search for the TP53 mutation (associated or not with the expression of the STAP2 and G3BP2 genes)
- the age of the dog
- the bone marrow infiltration rate
- whether or not APAVAC immunotherapy was combined with CHOP chemotherapy,
was designed to estimate the dog's probability of survival at 90, 180 days, one and two years.
The aim of this tool is to estimate the relevance of combining autologous APAVAC immunotherapy with the probability of survival of the treated animal, and it is an important tool in the therapeutic decision-making process and in discussions with the owner.
|
|
|
|
Data obtained from the chart comparing, at 1 year follow-up, the percentage of dogs whose lymphoma has not progressed (TTP) and the percentage of dogs surviving the lymphoma (LSS). exchanges with the owner.
|
How to proceed
Analysis of TP53 gene mutations is now available in the veterinary laboratory. Once the diagnosis of DLBCL has been confirmed on the basis of cytological and cytofluorimetric examination of the enlarged lymph node(s), it is advisable to isolate the lymph nodes during lymphadenectomy:
- firstly, a small fragment of the tumour (0.5 cm3) preserved in a physiological solution accompanied by a blood sample taken under EDTA to be sent within 24 to 48 hours for TP53 analysis.
- on the other hand, a fragment of approximately 1 cm3 (avoiding necrotic areas) stored at -18°C in a dry, sterile tube or pouch in order to anticipate, if necessary, the preparation of the autologous therapeutic vaccine APAVAC®.
On the basis of the results obtained during clinical staging, histopathological/immunohistochemical examination and TP53 screening, it will then be possible to consult the prognostic algorithm to identify the most appropriate therapeutic alternatives.
For example, a 7-year-old dog with a lymphocyte infiltration rate of 5% in the bone marrow and a mutated TP53 gene is predicted to have only 0.1% non-progression at 1 year, with a lymphoma-specific survival of only 0.5% (see figure).
Modification of the parameters TP53 mutation or not and APAVAC immunotherapy, combined or not with chemothe
|
|
|
|
To conclude
With 10 years' experience and more than 1,000 animals treated, without any reported toxicity or side-effects, the autologous therapeutic vaccine APAVAC® has amply demonstrated its clinical efficacy in the treatment of numerous animal cancers, with or without chemotherapy.
As with all targeted therapies, personalised treatment means that the most precise and effective alternative can be offered to each patient.
When the gene is not mutated, the search for the TP53 mutation can further improve the survival prognosis of an animal treated with this specific immunotherapy..
|
|
|
|
Would you like to talk about using APAVAC® on an animal you are treating?
Would you like to order?
Contact us by e-mail: sciences@hastim.fr or by telephone: 00 33 5 34 47 86 10
|
|
|
|
RÉFÉRENCES 1. Martini
V, Aresu L, Riondato F, Marconato L, Cozzi M, Stefanello D, et al. Prognostic
role of non-neoplastic lymphocytes in lymph node aspirates from dogs with
diffuse large B-cell lymphoma treated with chemo-immunotherapy. Res Vet Sci.
août 2019;125:130‑5.
2. Marconato
L, Aresu L, Stefanello D, Comazzi S, Martini V, Ferrari R, et al. Opportunities
and challenges of active immunotherapy in dogs with B-cell lymphoma: a 5-year
experience in two veterinary oncology centers. J Immunother Cancer. 7 juin
2019;7(1):146.
3. Marconato
L, Frayssinet P, Rouquet N, Comazzi S, Leone VF, Laganga P, et al. Randomized,
placebo-controlled, double-blinded chemoimmunotherapy clinical trial in a pet
dog model of diffuse large B-cell lymphoma. Clin Cancer Res Off J Am Assoc
Cancer Res. 1 févr 2014;20(3):668‑77.
4. Lacroix
M, Linares LK, Le Cam L. [Role of the p53 tumor suppressor in metabolism]. Med
Sci MS. déc 2013;29(12):1125‑30.
5. Mendiratta
G, Ke E, Aziz M, Liarakos D, Tong M, Stites EC. Cancer gene mutation
frequencies for the U.S. population. Nat Commun. 13 oct 2021;12(1):5961.
6. Schaafsma
E, Takacs EM, Kaur S, Cheng C, Kurokawa M. Predicting clinical outcomes of
cancer patients with a p53 deficiency gene signature. Sci Rep. 25 janv
2022;12(1):1317.
7. Das S,
Idate R, Regan DP, Fowles JS, Lana SE, Thamm DH, et al. Immune pathways and
TP53 missense mutations are associated with longer survival in canine
osteosarcoma. Commun Biol. 11 oct 2021;4(1):1178.
8. Wang
G, Wu M, Durham AC, Radaelli E, Mason NJ, Xu X, et al. Molecular subtypes in
canine hemangiosarcoma reveal similarities with human angiosarcoma. PloS One. 2020;15(3):e0229728.
9. Aresu L, Agnoli C, Nicoletti A, Fanelli
A, Martini V, Bertoni F, et al. Phenotypical Characterization
and Clinical Outcome of Canine Burkitt-Like Lymphoma. Front Vet Sci. 17 mars
2021;8:647009.
10. Aresu
L, Ferraresso S, Marconato L, Cascione L, Napoli S, Gaudio E, et al. New
molecular and therapeutic insights into canine diffuse large B-cell lymphoma
elucidates the role of the dog as a model for human disease. Haematologica.
juin 2019;104(6):e256‑9.
11. Giannuzzi
D, Marconato L, Fanelli A, Licenziato L, De Maria R, Rinaldi A, et al. The
genomic landscape of canine diffuse large B-cell lymphoma identifies distinct
subtypes with clinical and therapeutic implications. Lab Anim. juill
2022;51(7):191‑202.
12. Giannuzzi
D, Marconato L, Cascione L, Comazzi S, Elgendy R, Pegolo S, et al. Mutational
landscape of canine B-cell lymphoma profiled at single nucleotide resolution by
RNA-seq. PloS One. 2019;14(4):e0215154
|
|
|
|
|
|
