Deel 4:
Then the pediatric studies are very high on the agenda to start later on during the second half of this year. As you know, there is already patients included up to until the age of 12. So, we're looking at the below-12s and it will be two pediatric studies starting in this perspective.
As I was alluding to earlier, we're very excited about the prospect of making the move to Japan with this compound. We've had incoming requests from Japanese opinion leaders to please come to that -- to come and do a small trial. We had discussions with the Japanese authorities, and they're all very cooperative and we anticipate to be able to, this year, start that small Japanese clinical trial that is required for Japanese authorities to take this under review.
And then, of course, we're anticipating the big moment, assuming this accelerated review by the FDA, which calls for an eight-month review cycle that we will be able to launch the product or get at a PDUFA date in the first quarter of '23, quickly followed by the US launch. And then, of course, the EMA, because it was filed later, will follow on later on with an approval.
And then subsequently to that, in the second half of next year, we anticipate the launches in the EU countries to be rolled out across the EU. So, we're very excited about this prospect. As I was already saying, this is the route map to totally transforming the company towards a multiple company in multiple geographies, and it will take place during next year, for which we are, of course, investing very heavily.
Speaking about investments, it's probably a good moment to switch over to our Chief Financial Officer, Jeroen Wakkerman, who's sitting next to me here. And we may actually go to Slide 21.
Jeroen Wakkerman
Thank you very much, Sijmen, indeed.
On the next slide, you will see the quarterly development of revenues from RUCONEST over the last two years. And we're very pleased to say that we increased the revenue in Q1 2022 by 7% to $46.6 million. And out of that, as -- it may not be a surprise to you, most of it is from the US revenues. $45.3 million out of the $46.6 million of revenues was from the US, and that meant an increase in the country of 7% in revenue growth.
And the increase that we saw in the number of patients was a driver of it, and it was slightly offset by tighter inventory management at larger specialty pharmacies. And -- well, as you see, the EU and rest of the world are still small, was not a strong quarter for EU and the rest of the world, but that was largely due to phasing of orders.
The gross profit increased by 8% to $41.7 million and that was, obviously, mainly due to growth in revenues, but also the margin obviously increased with this growth number. And that is a combination of price increases and less discounts that we had to offer. So a margin improvement.
Going two slides on, please. Yes, that one. The operating profit decreased to $2.8 million from $6.3 million last year, and that was because of the expected increase in operating expenses. The operating expense increased to $39.8 million. That's an increase of about $7 million. And that $7 million increase was a combination of several things, but half of it was because of the launch preparations for leniolisib. Other elements are increased travel activity in the U.S. post-COVID and phasing of costs. I think this is the wrong slide.
Operator, could you put up the right slides, please?
Operator
The financial highlights from Q1, Slide 3.
Jeroen Wakkerman
Three out of five, correct. So I'm now at the -- I was saying that the operating profit decreased because of the cost increase and that was half of it was because of the announced increase in cost for the leniolisib launch preparation. Net profit decreased to $3.5 million, and that was caused obviously by the operating expense increase, as I just mentioned, but also a decrease in the finance income from last year.
Last year, we had a big foreign exchange effect because of the euro-dollar volatility and we didn't gain as much from that this year. The cash position is still very strong. It decreased by $2.2 million, but it's still at $189.7 million, and the positive cash flows from operations amounted to positive $0.6 million. And that is obviously increasing the -- sorry, including the increased cost from the leniolisib launch preparation.
On the next slides, we see the summary of this. Again, a profit before tax going from 12.8 to 4.2, and that was caused by underlying business gross profit, $3 million, mainly from the U.S., increased R&D expenditure because of leniolisib and some brands and that was related to phasing, a slight increase in G&A expenditure and most of the increase in marketing and sales expenditure is also due to leniolisib. Financial results from the -- that change was due to foreign exchange. Last year, financial results were $6.6 million, now $1.8 million. And therefore, we come to a profit before tax of $4.2 million.
And on the next slide, you see some more detail on the cash and cash equivalents, again, a decrease of $2 million, and that is because of an increase in operating cash flows offset by working capital changes. We invested very little in Q1. That's expected to go up in the next few quarters. And the financing cash flow is mainly interest and lease cost. So again, a strong cash position that we will, amongst others, use for the leniolisib launch preparations.
And with that, I would like to go to the next slide please to the outlook and hand over to Sijmen.
Sijmen de Vries
Thank you very much, Jeroen.
And yes, the outlook, ladies and gentlemen, has been -- has not changed from the previous outlook that we have announced as a result of our full year results. So we continue to guide for single-digit growth in the group revenues from RUCONEST. Quarterly fluctuations in revenues are to be expected though. We still, as already stated, we are on track for Q1 '23 launch of leniolisib, subject of course to regulatory approvals.
Company will continue to invest, as you have seen in these launch preparations and the clinical development obviously for the trials that I have outlined before. And this will of course significantly increase, as you have seen a significantly impacted profit as we have seen already. But it is also to be stated, and I said that before, that the RUCONEST cash flows will be able to fund these investments.
So no additional financing will be needed to execute on all these things. We will also continue to invest in potential acquisitions or in-licensing of new late-stage development opportunities, as I have alluded to before, in rare diseases. And of course, if you think about in-licensing, but especially acquisitions, there may be additional financing required, which of course, can then come from our strong balance sheet, access to debt capital and access to eventually equity capital as well, certainly in the case of acquisitions.
And last but not least, we will continue also to be able to focus on the strategic development of the company going forward and think about the additional indications, for instance, for a compound leniolisib that can be explored towards the future. And of course, our early-stage compounds will continue to be developed.
So with that said, I would like to conclude this part of the meeting and go over to the next slide and switch the -- open the floor for questions to everybody who's attending. Thank you very much. Operator, please open the floor for the questions.