Integration of Laguerre polynomial $\int_{0}^{x}u^{p-1}(1-u)^{q-1}e^{-\theta u}L_n^{(m)}(\theta u)\mathrm du$

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It's been several days that I'm confronted to this integral, without much success in its resolution.

To give you more details, in my case:

  • $n$ is an integer $>1$
  • $m=n-2$
  • $p,q \in \{n-1, n\}$
  • $x \in [1/2, 1]$
  • $\theta \in (-\infty, 0]$

The integral becomes:

$$\int_{0}^{x}u^{p-1}(1-u)^{q-1}e^{-\theta u}L_n^{(n-2)}(\theta u)\mathrm du$$

I am aware of a close form for $x=1$ (from $\textit{Table of integrals, series and products}$, Gradshteyn and Ryzhik, eq (7.415)), but I can't find any for an arbitrary $x$.

I have tried several approaches, such as transforming the Laguerre polynomial into hypergeometric function, or developing $(1-u)^{q-1}$ with the Newton formula to recombine later, but non of them were successful.

Could someone help me with finding wether or not there is a close form formula for this integral, and give me some insight in the case it does?

Thank you in advance.