What is a biomarker?

A biomarker is intended to function as a surrogate endpoint. A surrogate endpoint is intended to substitute for a clinical endpoint. A clinical endpoint is a characteristic or variable that reflects how a patient feels, functions, or survivability.

The word surrogate actually comes from the latin word subrogare, which means to substitute.

So, a biomarker is a characteristic that is objectively measured and evaluated as an indication of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. A biomarker is an objective indications of medical state observed from outside the patient.

Also, a…


Most pharmaceutical companies adhere to the ICH E3 guideline “Structure and Content of Clinical Study Reports” when creating a clinical study report (CSR). For exposure analysis , the ICH guideline recommend that the investigational products should be characterized by:

. The number of patients exposed

. The duration of exposure

. The dose to which they were exposed.

Therefore, the following items could be needed in your TFL:

. Duration of treatment

. Number of cycles received 

. Number of patients with dose adjustments 

. Reasons for dose adjustments 

. Dose intensity as a percentage of dose…


When designing ADaM analysis datasets, you may have various needs for data categorization. A primary need to categorize data is to group similar values for your analysis.

ADaM standard allows you to create variables that categorize the information in your dataset. These grouping variables are to be used during the analysis.

New PARAM and PARAMCD iteration can be created if the standard mapping rules give you limitation when creating grouping variables. In that way you will avoid mapping rule violation.

PARCAT PARAMETER CATEGORIZATION PARCATy

This kind of grouping variable is intended to group PARAM values into categories. PARAM to PARCATy mapping has to obey…


Source : https://en.wikipedia.org/wiki/Pharmacokinetics

PK contribute to the label once the drug has been approved. PK analysis are mainly used in phase one studies. It can have an impact on the study design and cause a change in it. For example, it can affect the frequency at which the study drug doses will be administered.

When a drug is administered it goes through 4 phases:

1) Absorption: How the drug gets into the blood. For example, the route of administration of the drug can affect absorption. The concept of absorption is not applicable to a drug that is directly injected into the blood.

2)…


Programmers are often called upon to program survival analysis and produce tables and figures (For example: Kaplan Meier Curves). Performing such analysts often time involves using PROC LIFETEST

What is survival analysis and the kaplan-meier analysis?

Survival Analysis represents a set of statistical methods used to estimate the length of time between two clearly defined events. Survival data is often analyzed in terms of time to event. In an analysis with clinical trial data, it is often referred to as time to response or time to failure analysis (For example: Time to responding to a treatment or relapse or death). Survival analysis estimates the probability of survival as…


The RETAIN statement determins the initial value for a variable The syntax of the RETAIN statement allows it to specify an ‘initial value’ — i.e. its value at the start of the very first iteration of the DATA step. So we can initialize the variable by assigning a constant value or assigning a value that comes from another variable.

The RETAIN statement retains SAS value in the PDV for the duration of an iteration or multiple iterations. …


Real world evidence must be considered as a complement of randomized controlled trials (RCT). An RCT is always considered higher in the evidence ladder. Most of the time real world study are done prospectively.

Even though real-world evidence studies have lower evidential value than RCT, some techniques can be used in order to mimic RCT. One such technique is propensity score method.

These methods allow to estimate in which treatment arm the subject would have been assigned in an RCT. This is estimated based on his baseline characteristics.

In an RCT the hypotheses testing is done in a double blinded…


The Response Evaluation Criteria in Solid Tumors (RECIST) provide standards for solid tumor response assessments. The resist method requires to measure the overall tumor burden at baseline and use it as comparator for subsequent measurements.

Using the RECIST standard you can obtain the following response for a solid tumor

  • Complete Response (CR),
  • Partial Response (PR),
  • Stable disease (SD),
  • Progressive (worsening) disease (PD),

There are 3 types of lesion in the overall tumor response assessment.

  • Target lesions are defined as those followed quantitatively. Theye are measured at every visit, and their measurements are added to get the sum of diameters.
  • Non-target…

Introduction

In oncology, the laboratory data plays a significant role in determining the safety of a drug compound. Therefore, it plays a big role in the process of approval of the drug. However, some issues can arise while performing ADaM programming for laboratory results. Therefore, it is very important for a statistical programmer to pay attention to some key points.

One to one relationship between PARAMCD and PARAM

When programming any ADaM, you have to make sure that there is a one-to-one correspondence between PARAMCD and PARAM. When programming ADaM laboratory dataset there could be some element which can create a problem regarding that.

In laboratory data, PARAMCD and…


As we have seen in a previous post, the syntax of SAS PROC TABULATE can be challenging. However, as a statistical programmer it is essential to know this SAS procedure.

There are several important statements to manipulate in PROC TABULATE. these statements are:

  • VAR
  • CLASS
  • TABLE

In addition, in the TABLE statement you can use commas as operators.

So, let’s see that through a first example:

Let’s first create the dataset on which we will work.

data subjects ;
retain USUBJID AGE LOCATION TREATMENT ;
length TREATMENT $25 ;

input USUBJID $ AGE LOCATION $ TREATMENT $ ;
datalines…

Christian Baghai

Consultant clinical statistical programmer

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