Spot the Difference: Effect of TK blood

Transcription

1 Spot the Difference: Effect of TK blood sampling on Clinical Pathology parameters Fiona McClure Clinical Pathology

2 What to Spot? Clinical Pathology Parameters What are Reticulocyte s? Unusual finding Reticulocyte sub populations In life blood sampling: A retrospective study Results of DBS study Conclusion

3 Reticulocyte Spotting? FBC/CBC Standard parameters: Hb, RBC s, Hct, WBC s, Plt s and Total Reticulocyte Count (LFT s U s & E s) Reticulocytes are immature red blood cells which originate in the bone marrow but are released in to the peripheral blood stream to complete their differentiation in to mature red blood cells. Automated counting: Light absorbed by reticulocytes is proportional to their intensity of staining and therefore their RNA content Three populations of low, medium and high RNA content reticulocytes defined: Non-standard parameters not routinely used. Timing of the reticulocyte measurement is important as about 4 days are required for a substantial reticulocyte response to occur.

4 Spot the unexpected: 1 Month Toxicology Rat Study To assess the pharmacological effect of a compound on our Haematology parameters we took haematology samples on Day 4 (from TK animals) Expected pharmacology results Also noticed minor changes in Hb and Reticulocyte counts (When compared to our biological variation) Hb lower than expected Retic higher than expected Both treated and control animals

5 350,0 Males 300,0 250,0 200,0 150,0 100,0 Biological Range Study Controls Test Article Test Article Test Article Test Article 50,0 0,0 Haemoglobin Total Reticulocyte Count

6 450,0 Female 400,0 350,0 300,0 250,0 200,0 150,0 BV Co TA TA TA TA 100,0 50,0 0,0 HB RET

7 1 Month Toxicology Rat Study To assess the pharmacological effect of the compound we took haematology samples on Day 4 (from TK animals) Expected pharmacology results Also noticed minor changes in Hb and reticulocyte counts Hb lower than expected Retic higher than expected Why? TK Bleeding Days 1/2 at least 200 L taken each time point All groups including controls TK Bleeds sampled up to 6 times over a 24-hour period (approximately 200 to 350 L blood per sample) Between mls removed (7.6 15% of CBV)

8 Blood Volume (ml) Spot the Blood Volume Limits - Rats Blood Volume Limits - Rats Body Weight (g) 10% CBV (ml) as single sample 15% CBV (ml) in 4 weeks Max 20% CBV (ml) in 4 weeks, if killed 1 hour after last sample or end of TK profile in which 15% CB

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13 450,0 Female 400,0 350,0 300,0 250,0 200,0 BV Co TA TA TA TA 150,0 100,0 50,0 0,0 HB RET

14 70 Female reticulocyte subpopulations compared to BV BV Control 5 mg/kg/day 15 mg/kg/day 50 mg/kg/day 150 mg/kg/day %LAR %MAR %HAR

15 In Life Blood Sampling (SD Rats) Standard candidate selection studies use toxicology groups and satellite group for TK data typically 16 plus 9 males If enough compound then only the satellite animals bled for TK, Days 1/2 and 7/8: 0.5, 1, 2, 4, 8 and 24 hours after dosing ( L) If not enough compound then the Tox animals are bled on Days 7/8 for TK What effect on Clinical Pathology parameters?

16 INVESTIGATIONS INTO CONSEQUENCES OF IN-LIFE BLOOD SAMPLING Retrospective data analyses 7D studies Six studies where Group 1 (Control) animals were not sampled during the in-life phase Six where Group 1 (Control) animals were sampled up to 6 times over a 24-hour period (approximately 200 to 350 L blood per sample) on days 7/8 Looked at control animal data only, N=4 Males per study Clinical Pathology Standard profile Plus reticulocyte sub populations (non-standard: on raw data printouts)

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18 Toxicokinetic bleed vs Toxicology bleed Can we: Improve our studies reduce our animal number Refine our processes Minimise the impact on clinical pathology parameters

19 Dried Blood Spot study (SD Rats) N=4/sex/group Terminal bleeds for Haematology Day 8: all animals. Groups were: Restrained but not bled until terminal bleed on Day 8(i.e. no in-life) Control Standard TK profile bleed Day 1/2 (approx 100 L blood per time point) up to 3.8 %CBV Standard TK profile bleed Day 7/8 (approx 100 L blood per time point) : up to 3.8% CBV Standard TK profile bleed Day 1/2 and 7/8 (approx 100 L blood per time point) up to 7.6% CBV Standard TK profile bleed Day 1/2 and 7/8 (approx 40 L blood per time point): up to 3.1% CBV

20 Control 600 µl (2.2%) Day 1/2 600 µl (2.0%) Day 7/ µl (4.4%) 480 µl (1.8%) Day 1/2 and 7/8 Day 1/2 and 7/8 Haemoglobin Total Reticulocyte count

21 140 Males Control 600 µl (2.2%) Day 1/2 600 µl (2.0%) Day 7/ µl (4.4%) Day 1/2 and 7/8 LRT# MRT# HRT# 480 µl (1.8%) Day 1/2 and 7/8

22 180 Females Control 600 µl (3.8%) Day 1/2 600 µl (3.8%) Day 7/ µl (7.6%) Day 1/2 and 7/8 480 µl (3.1%) Day 1/2 and 7/8 LRT# MRT# HRT#

23 On the Spot: Conclusions Reticulocytes sub-populations are a This good reliable data is early from marker SD of rats: bone now marrow activity Can give an indication of the time of insult talk of moving to HW rats TK blood can be taken from Toxicology animals using blood spot technique without adversely affecting standard parameters Genetic Toxicology Micronucleus results can be Taking 40 L blood sample minimises effect This data has formed part of the basis for proposing the removal of satellite affected rats from by non-glp reticulocyte toxicity studies changes

24 Blood Volume (ml) Blood Volume Limits - Rats Blood Volume Limits - Rats Body Weight (g) 10% CBV (ml) as single sample 15% CBV (ml) in 4 weeks Max 20% CBV (ml) in 4 weeks, if killed 1 hour after last sample or end of TK profile in which 15% CB